The effect of printing parameters on crushing behavior of 3D printed Nylon and CF/Nylon samples using Powder Bed Fusion and Material Extrusion techniques

The effect of printing parameters on crushing behavior of 3D printed Nylon and CF/Nylon samples using Powder Bed Fusion and Material Extrusion techniques | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The effect of printing parameters on crushing behavior of 3D printed Nylon and CF/Nylon samples using Powder Bed Fusion and Material Extrusion techniques mina adel hanna, Sameh Habib, Khaled Abdelghany, Tamer Samir Mahmoud This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2948690/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract 3D printing techniques are becoming more common within several industrial fields due to their many benefits. These benefits include customized properties of final products, design independence, demand-driven manufacturing, waste alleviation, and the ability to produce complex parts, as well as fast prototyping. Parts manufactured using the powder bed fusion or material extrusion process are achievable by various building parameters. In this investigation, a comprehensive study was undertaken to clarify the variation in the compressive and impact strength of SLS prepared Nylon Polyamide and FDM prepared Nylon/CF parts at different building parameters. Significant methodological parameters were studied: infill patterns/layer layouts (triangular and rectilinear), wall thickness (1.2, 3.6, 6) and infilled density (70, 85 and 100%), utilizing material extrusion and powder bed fusion 3D printing machines. The Central Composite Face-centered (CCF)method was applied to design an optimal number of experiments. Experimental results demonstrated that Nylon Polyamide and Nylon/CF samples present slightly different crashing patterns and mechanical behaviors when tested for compression and impact. Compression characteristics of all tested samples are a progressive folding and lateral shearing failures amalgamation. Rectilinear samples are mechanically weaker than Triangle samples. Selective laser sintering Fused deposition modeling Polyamide powder Short Carbon fiber Compression Impact Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1 Introduction Traditionally, solid freeform fabrication (SFF) approaches have been engaged in the rapid prototyping technique, primarily for visualization or kinematic functionality, such as in the case of a mechanism with moving parts. The development of rapid prototyping for industrial and engineering applications is a recent phenomenon PS D'Urso and MJ Redmond [ 1 ], [ 2 ]. As industrial companies have several ways to fabricate their products with much less time by depending on many manufacturing processes to hit the marketplace in time and maintain client demands [ 3 ]. One of those major and higher-level techniques is Additive Manufacturing (AM) owing to the ability to fabricate finished (or at least near finished) products directly from the CAD version with no human interference [ 4 , 5 ]. AM has more advantages and applications in different fields than the conventional technique. AM applications are widespread over numerous industries, including aerospace, customized parts, customer products, sports and lifestyle, bio-medical implant products, and automobiles[ 6 , 7 ]. The real significance of AM is that it can effectively fabricate complex structures and assist the engineers in ideally designing external and internal (print temperature, infill, and layer thickness) geometries and thereby effectively reduce costs and manufacturing time [ 8 ]. Different additive manufacturing technologies are based primarily on three categories of construction: sintering or melting of powder, deposition of filament and solidification of a liquid (resin) material. For each of these technologies, several different techniques have been innovated, like selective laser sintering (SLS), fused deposition modelling (FDM) or stereolithography (SLA)[ 9 ]. The patent expiration of these techniques, first for FDM, and later SLA and SLS, has stimulated curiosity regarding how to enhance and improving these techniques. The seed of this curiosity is the RepRap project, which aims to provide open source 3D printing designs to help construct 3D printer machines[ 10 ]. One feature of this new methodology was to construct relatively small machines to be desktop 3D printers, developing a new industry presently termed ‘‘desktop 3D printing.’’ This involves sharing on the internet the successful and disruptive components for the design as well as the building instructions for constructing similar printers by anyone including a large percentage of the building components. This leads to an exponential increase in 3D printing users, new designs, and enhancements that have never been carried out by the patent owner. A considerable number of desktop 3D printing companies have been established from this project[ 11 ]. Selective Laser Sintering (SLS) is a crucial Additive Manufacturing (AM) technology that can create tissue-engineered scaffolds and intricate three-dimensional parts by fusing powdered material layer by layer to produce a final product[ 12 ]. the SLS process uses a CO2 laser to selectively sinter thin layers of powder that are spread one above the other on a constructing bed. The building bed is on top of the rolling cylinder and goes down leaving a small gap that specifies the powder layer thickness. At the same time, the platform of the other feeders goes upwards to raise the powder to a sitting for collecting and spreading by the roller, filling the small gap, thereby spreading the first layer of powder. After that, the powder layer temperature is raised below the sinterisation point of the substance, known as the bed temperature of the part. Subsequently, scanning of the laser beam takes place on this layer, providing the required energy for selectively sintering the powder particles according to the cross-section contour of each object layer (computerized by a slicing program). After the sinterisation of this powder layer, another layer is spread on top of the existing one and this process is repeated according to the slicing program until the structure of the desired product is finished[ 13 – 15 ]. This enables the creation of highly complex parts, avoiding the difficulties of conventional subtractive manufacturing forms, or processes with high tooling costs like injection molding. However, the sintering process of polyamide materials (which constitute 95 percent of polymer material used in AM[ 16 ]) produces porous, lightweight structures, but they have poor mechanical behaviors due to the small bonds and un-sintered powder[ 17 ] and thus have seen little use in major load-endurance applications. This is one of the biggest obstacles to 3D printing. Polyamide 12, also known as nylon or PA12, is a commonly used material for Selective Laser Sintering (SLS) due to its eco-friendly nature and ease of sintering with a laser beam compared to other polymers[ 18 – 21 ]. In a powder form, Different commercial names are available for this product, such as PA 2200 (from EOS, Krailling, Germany), Duraform PA (from 3D-Systems, Rock Hill, SC, USA), or Nylon 12 (from Formlabs, Somerville, MA, USA). The mechanical behaviors of PA12 fabricated by SLS may differ roughly according to the SLS process variables and the anisotropy[ 22 ]. FDM has shown to be inexpensive, with the easiest printing and the most widespread technology of AM in marketplaces nowadays [ 23 ]. FDM 3D printing technology mainly depends upon the concept of molten polymer filament extrusion. The thermoplastic polymer is molten at a relatively high temperature (200–280 o C), and then the melted plastic filament (thread) is fed from the movable nozzle via a knurled feeder onto the heated bed, which is usually made from glass or aluminum[ 23 , 24 ]. The filament is heated to semiliquid state and moved in both horizontal and vertical directions simultaneously to fabricate layer-by-layer deposition [ 25 ]. In this regard, the FDM term is a Stratasys trademark, and this technique is equivalent to Fused Filament Fabrication (FFF), which was described in 2015 by ISO/ASTM as a material extrusion process[ 26 ]. This technique can achieve several thermoplastic polymeric synthesis feedstocks using FFF for additive manufacturing (AM), increasing availability and use in the industry. Polylactide acid (PLA) has been extensively used as FDM material because of its excellent printability, eco-friendliness, and mechanical performance[ 19 ]. Moreover, PLA is commonly used as a biomedical material because of its biocompatibility and biodegradability [ 27 , 28 ]. Therefore, PLA has significant potential as a FFF building material and fabricated lattice structures used as synthetic bone scaffolds[ 22 ]. The mechanical properties of 3D-produced products are important in the field of rapid prototyping; thus, the prototype must have sufficient mechanical strength and proper surface quality for engaging in engineering purposes. Mechanical behaviors become important in the field of rapid manufacturing where the surface finish, strength, and stiffness must be suitable to meet operation and in-service loading requirements, and where they should be comparable to those produced using conventional manufacturing routes to make these processes competitive[ 29 ]. In one of their studies, Ngo et al[ 30 ] stated that AM technology builds a part by layers. Layers are fabricated by the machine and each layer is joined together to produce or create the final 3-D model. Ilaria et al. [ 31 ] claimed that the potential of the technique is restricted by the lack of large-scale applications, the improvement of design building information, and the life-cycle cost of the 3D printed parts. Hooreweder et al. [ 32 ] confirmed that 3D printed products need improved mechanical behavior if they are to be competitive with conventional manufacturing forms. Furthermore, Monzon [ 33 ] stated that plastic composites produced by AM “need to be more improved” as they have become primary parts in the aerospace and automotive industries. A study by Can Tang et al. [ 34 ] revealed that both printing speed and printing temperature have a significant impact on elastic modulus and tensile strength. The elastic modulus and tensile strength increase with a high printing speed. F. Saenz et al. [ 35 ] have also examined Young’s Modulus, Yield Strength and Ultimate Strength of 3D printed ABS with input parameters of layer thickness, raster pattern and infill percentage using the Taguchi technique. There is proof that infill percentage, layer thickness and the interaction layer thickness-raster pattern cause variation in Young’s Modulus, Yield Strength and Ultimate Strength discussed by Bartolomé et al [ 36 ]. Tymrak et al. [ 37 ] found that tensile and yield strength, stiffness, and modulus elasticity of the part increase by increasing the infill density, although the increases in infill deposition rate decrease the tensile and yield strength of the part. The yield strength and tensile strength of 3D printed products are influenced by many infill designing parameters (infill deposition rate, infill density, and layer thickness) and the mechanical characteristics stated by Johnson et al. [ 38 ]. Suteja et al. [ 39 ] investigated this topic and found that the infill density increases the 3D printed product density. A higher density product has a higher yield and tensile strength. The smaller the gap, the greater the resistance moment. A higher moment resistance needs a higher break bending moment. Hence, it possesses higher flexural strength. Most studies only engaged in a single material and a single technique to study the process parameters on the mechanical performance of the product and focused only on flexural, tensile and fracture properties, completely disregarding the differences in techniques and material properties and their effect on compressive strength and impact. So, the main goal of the current article is divided into two main parts. The first aim is using two different material types as: powders and filaments. While the second goal is applying advanced manufacturing technology of additive manufacturing as: FDM and SLS 3D techniques. Specifically, this study investigates the influence of process parameters of Nylon Polyamide (powders) and Nylon/CF (filaments) samples via FDM and SLS 3D techniques as: (i) building patterns, (ii) infill percentages, and (iii) wall-thicknesses on the mechanical characteristics especially impact and compressive strength. 2 Experimental procedure 2.1 Materials In this work, Polyamide 12 White powder, also known as Nylon (supplied by EOS GmbH, Germany) and Carbon Fiber Polyamide (Nylon) Filament of diameter 1.75 mm (supplied by ESUN, China) were used as feedstock. The whitish fine powder (PA 12) has acceptable balanced properties such as high strength and stiffness, biocompatibility confirmed by EN ISO 10993-1 and USP/level VI/121°C, good chemical resistance, and constant behavior for the long-term. Carbon Fiber Nylon Filament consists of 80% nylon and 20% chopped carbon fiber. Carbon Fiber polyamide (Nylon) Filament has lower shrinkage, excellent thermal and chemical resistance, strong layer bonding, higher strength and rigidity and good toughness compared with ordinary nylon. According to the datasheet, the mechanical properties of PA 12 [ 40 ] and carbon fiber reinforced Polyamide CF/PA filaments [ 41 ] are summarized in Table 1 2.2 Specimen design and the 3D printing process SLS and FDM 3D printers were used to fabricate the NYLON (PA 12) and Polyamide-CF samples, respectively. Table 1 Mechanical properties of Polyamide 12 powder and Polyamide-CF filament Polyamide 12 powder Mechanical properties Value Unit Test Standard Tensile Modulus 1700 MPa ISO 527-1/-2 Tensile Strength 48 MPa ISO 527-1/-2 Flexural Modulus, 23°C 1500 MPa ISO 178 Flexural Strength 58 MPa ISO 178 Izod Impact notched, 23°C 4.4 kJ/m² ISO 180/1A Izod Impact unnotched, 23°C 32.8 kJ/m² ISO 180/1U Shore D hardness (15s) 75 - ISO 868 Ball indentation hardness 78 MPa ISO 2039-1 Polyamide-CF filament Tensile Strength 140 MPa GB/T 1040 Elongation at Break 10.61 % GB/T 1040 Flexural Strength 140 MPa GB/T 9341 Flexural Modulus 4363 MPa GB/T 9341 IZOD Impact Strength 18.67 kJ/㎡ GB/T 1843 2.2.1 Selective Laser Sintering Selective Laser Sintering (SLS) 3D printer, FORMIGA P 110 (EOS Additive Technologies GmbH, Germany), was utilized to produce pure NYLON (PA 12) samples from its initial form as powder. EOS Parameter Editor, EOS RP Tools, PSW 3.6 software was used to adjust the printing parameters and extract the G-Code desired for the selective laser sintering (SLS) process. The SLS printing process parameters were based on the recommendation of the supplier (see Table 2 ). This SLS printer should meet all the minimum requirements for printing the samples for mechanical experiments. Table 3 presents the specification of the EOS FORMIGA P 110 SLS 3D printer [ 42 ]. Figure 1 presents the FORMIGA P 110 SLS Printer and impact and compression samples of the triangle and rectilinear pattern configurations with three levels of wall-thickness and infill percentages to investigate their energy absorption capabilities and compression properties. Table 2 constant parameters during SLS printing process. Parameters Values Laser beam power 25 W Scan speed 3000mm/s bed temperature 169 ◦ C Layer thickness 100 µm Laser spot size ~ 0.2 mm Table 3 specification of EOS SLS 3D printer. Properties Specifications Building volume 200 x 250 x 330 mm (7.9 x 9.8 x 13 in) Laser type CO 2 ; 30 W Building rate up to 1.2 l/h Layer thickness (depending on material) 0.06–0.10–0.12 mm (0.0024–0.0039–0.0047 in) Precision optics F-theta lens, high-speed scanner Scan speed during build process up to 5 m/s (16.4 ft/s) Power supply 16 A Power consumption typical 3 kW, maximum 5 kW Dimensions (W x D x H) 1,320 x 1,067 x 2,204 mm (51.97 x 42.01 x 86.77 in) Weight approx. 600 kg (1.323 lb) 2.2.2 Fused Deposition Modeling Fused Deposition Modeling (FDM) 3D printer, CREALITY Ender-3 (CREALITY-3D Printing, China), was utilized to produce Polyamide-CF samples from its initial form as filament. Ultimaker Cura, Ultimaker Cura 4.3 software was used to modify the printing parameters and obtain the G-Code required for the FDM process. The Fused Deposition Modeling (FDM) printing process parameters, as shown in Table 4 , were chosen based on the recommendations of the materials supplier. The CREALITY Ender-3 FDM 3D printer has the necessary specifications to produce the specimens for mechanical testing. The features of this FDM printer are shown in Table 5 . Figure 2 presents the CREALITY Ender-3 FDM Printer and impact and compression samples. Before printing, the CREALITY Ender-3 3D printer needs to be calibrated manually. Calibration should be done in the all-moving axis (X-Y-Z) for printing samples at high accuracy. The alignment of the three axes with the horizontal ground axis should be 180° for high-precision printing. The hot table should also be adjusted before printing. The gap between the hot table and the nozzle should depend on the nozzle size, which can be measured with a feeler gauge. The nozzle distance should be uniform across the hot table. It is also important to make sure that the filament is extruded smoothly during printing without any irregularities or leakage on the printed table [ 43 ]. For reducing the effect of factors not directly related to manufacture, it is essential to clean the printer nozzle after each 10 printed specimens as a result of deterioration of geometrical printing accuracy [ 44 ]. Table 4 constant parameters during FDM printing process. Parameters Values Nozzle Diameter 0.4 mm Layer Height 0.1 mm Perimeters Speed 25mm/s Infill Speed 40 mm/s Bed Temperature 90 ◦ C First Layer Temperature 240 ◦ C Other Layers Temperature 230 ◦ C Fill Angles, 45 ◦ , -45 ◦ Table 5 specification of Ender-3 FDM 3D printer [ 45 ]. Properties Specifications Technology FDM Print Area 220 x 220 x 250mm Nozzle 0.4mm Max. Extruder temp. 240◦C Max. ped temp. 120◦C Max. Print Speed 200mm/s Max. Layer Resolution 0.1mm Print Precision +/-0.1mm Weight 10 kg Firmware Marlin In this work, 2D rectilinear and triangle structures were selected to study the compression properties of fabricated samples as shown in Fig. 3. Selection of these structures will simplify an overall assessment of the effect of the material properties and geometrical features on the mechanical properties. SLS and FDM were used to 3D print structures with NYLON-POLYAMIDE powder and CF/NYLON Nylon filament with chopped carbon fiber, respectively. The specimens were printed in the same direction to avoid variation in mechanical properties due to printing orientation, as the print direction affects the mechanical characteristics of the 3D printed samples. Specimens were designed on the SolidWorks 2018 software. Each sample was designed according to its parameters, including wall thickness, infill pattern and infill percentage, as shown in Fig. 4 . Specimens were designed to open at one square face and close at another face to easily remove un-sintered powder material after finishing the SLS printing process. The specimen was printed in such a way that the closed square face was seated on the print bed, while the printing direction was up along the Z axis. Each specimen was designed according to ASTM standards for mechanical experiments. All designed samples were saved as STL Files and then copied to the slicing software using a flash drive. Printing parameters were adjusted by the slicer. Finally, G-code was generated from the slicer and transferred to the 3D printing machine. This experimental investigation was established based on selecting three controllable parameters from several 3D-printing factors. These parameters are infill percentage, infill pattern and wall thickness. This investigation involved three levels for infill percentage and wall thickness, and two levels for infill pattern. Response Surface Methodology (RSM) is a powerful statistical technique used to study the effects of multiple independent parameters on one or more responses. It is commonly used in experimental design as an effective way to optimize complex processes [ 46 , 47 ]. The RSM technique depends upon mathematical models such as linear, square polynomial functions, and others for fitting the experimental results that emerged from the designed experiment. Also, RSM is a statistical technique that can be used for model validation. To perform the required calculations, each independent parameter was coded at three levels, + 1, 0, and − 1, corresponding to the high-level, mid-level, and low-level, respectively [ 48 ], as shown in Table 5 . Table 5 variables with their code and levels for Central Composite- Face-centered Design. Triangle Values Parameters code -1 0 + 1 Infill percentage (%) X1 70 85 100 Wall thickness X 2 1.2 3.6 6 Rectilinear Infill percentage (%) X 1 70 85 100 Wall thickness X 2 1.2 3.6 6 The experiment was prepared depending upon a Central Composite- Face-centered Design (CCF) with two variables at three levels for each triangle and rectilinear pattern. CCF has high efficiency and is practicable. It is commonly applied for engineering process optimization for its relatively small number of experimental requirements [ 49 ]. The required number of experiments for developing CCF is 2 k + 2 k + n c , where 2 k and n c are the number of axial and central points, respectively. A total of 28 experiments were generated in this work, including nine experiments for each triangle and rectilinear pattern and five replicates at the central point for each triangle and rectilinear pattern as listed in Table 6 Table 6 Details of test samples S.No. Infill percentage Infill pattern Wall thickness 1. 100 Triangle 6 2. 100 Triangle 1.2 3. 100 Triangle 3.6 4. 100 Rectilinear 6 5. 100 Rectilinear 1.2 6. 100 Rectilinear 3.6 7. 85 Triangle 3.6 8. 85 Triangle 3.6 9. 85 Triangle 3.6 10. 85 Triangle 3.6 11. 85 Triangle 3.6 12. 85 Triangle 3.6 13. 85 Rectilinear 3.6 14. 85 Rectilinear 3.6 15. 85 Rectilinear 3.6 16. 85 Rectilinear 3.6 17. 85 Rectilinear 3.6 18. 85 Rectilinear 3.6 19. 85 Rectilinear 1.2 20. 85 Rectilinear 6 21. 85 Triangle 6 22. 85 Triangle 1.2 23. 70 Triangle 6 24. 70 Triangle 1.2 25. 70 Triangle 3.6 26. 70 Rectilinear 1.2 27. 70 Rectilinear 6 28. 70 Rectilinear 3.6 2.3 compressive testing In this investigation, the printed specimens were subjected to a compression test to examine their deformation patterns and generate corresponding stress strain curves. From these curves, crashworthiness parameters such as energy absorption (EA), specific energy absorption (SEA), and crushing force efficiency (CFE), were obtained. As stated in ASTM D695 international standard, the compression test specimen should be shaped as a cylinder or a prism with diameter/side to length ratio of 2 to 1. Prism specimens should ideally have dimensions of 12.7 * 12.7 to 25.4 mm (0.50 * 0.50 to 1 in.), while cylinder specimens should have a diameter of 25.4 mm and a height of 12.7 mm [ 50 ]. A cube specimen shape was selected for this study with dimensions of 20*20*40 mm. The compression tests were carried out at the Ministry of Scientific Research National Institute for Standards (NIS) on a universal testing machine (UTM) equipped with a load cell of 100 kN according to ASTM D695 standard. The cube specimens were placed at the center between upper circular and lower rectangular hardened steel plates and the specimens were subjected to a constant pressure at a rate of 5 mm/min until they were compacted. The experiments took place at ambient temperature. Optical images of all test samples were taken by a CANON 600D DSLR camera. The image was captured at a rate of one frame per two seconds. The experiments were carried out on 3D printed cube specimens to evaluate the basic mechanical properties of the NYLON and CF/NYLON under uniaxial compression. The tests ended at fracture or a strain of 50% of the specimen’s structure. The EA of the specimen structures during the compression test was calculated from the area under the stress–strain curve using the following formula (Eq. (2))[ 51 ]: EA = \({\int }_{a}^{b}\sigma .d\epsilon\) (1) Where σ is the compressive stress and the ε represents the nominal strain. The calculation of σ and ε are as follows: σ = F/A and ε = δ/H. F and δ are the compressive force and displacement, which are measured during the compression test. A is the original cross section area and H is the height of the structure along the compression direction. The SEA is derived from EA and specimen weight. SEA = \(\frac{EA}{m}\) (2) The mean crushing force (MCF) and crushing force efficiency (CFE) were calculated as follows: MCF = \(\frac{1}{{\delta }_{d}} \underset{0}{\overset{{\delta }_{d}}{\int }}F{\delta }_{d}\) (3) CFE = \(\frac{MCF}{IPF}\) (4) Where IPF is initial peak force 2.4 impact testing Charpy impact tests of 3D printed specimens were performed on a pendulum impact tester Zwick/Roell HIT (Zwick/Roell GmbH, Ulm, Germany) according to standard DIN EN ISO 179-1:2010 with standard notched test samples. The testing machine was equipped with a drop-weight hammer with 50 J impact energy. The measurements were obtained under specified working conditions with a 23°C room temperature and 50% relative humidity. The size of the impact specimens was designed according to ASTM D6110. with 12.7 mm × 12.7 mm × 127 mm as the maximum preferred notch dimension of specimens stated at the standard[ 52 ]. The amount of energy lost during the specimen fracture is directly proportional to the difference in the original and final pendulum height. The total fracture energy is obtained by the following equation. $${E}_{T}=mg({h}_{o}-{h}_{f})\pm 0.2J$$ 5 where \({E}_{T}\) is the total energy, \(m\) is the mass, \(g\) is gravitational acceleration, \({h}_{o}\) is the initial height and \({h}_{f}\) is the final height. The impact strength ( \({E}_{c}\) ) or absorbed energy per unit cross-sectional area (kJ/m2) is defined according to the standard ASTM D6110. $${E}_{c}=\frac{{E}_{T}}{wt}$$ 6 where the specimen width and thickness are \(w\) and \(t\) , respectively. The losses of energy due to the air resistance and bearing friction were neglected because of their negligible contribution to the energy balance. 3 Results and discussion 3.1 Compression properties 3.1.1 Triangular pattern samples The experimental results revealed that the 3D-printing of triangle pattern PA12 and PA-CF materials with different printing parameters such as infill percentage (70, 85, 100%) and wall thickness in mm (1.2, 3.6, 6) exhibited slightly different distortion patterns and mechanical properties when subjected to compression and impact tests. Compression distortion behaviors for all samples were a combination of progressive folding and lateral shearing failures. Specimens were successfully SLS- and FDM-printed without any defects. Nonetheless, rectilinear 3D printed samples are mechanically weaker than triangle samples, as a result of the sensitive lateral shear behaviors of rectilinear samples [ 53 ], causing them to be highly vulnerable to transverse plastic cracking at the outer sample surface. The triangle samples have an excellent bonding structure; thus, they have an acceptable mechanical property. The nominal stress-strain curves of PA12 and PA-CF printed with three different values of infill percentage and wall thickness for the triangular pattern under compression loading are presented in Fig. 5, along with photos captured at various loading stages. The equivalent compression stress is calculated as σ = F/A, where F is the equivalent compression load and A is the cross-sectional area of the sample, which is determined by A = L (length) × W (width). Generally, the crushing characteristic of 3D fabricated specimens during compression can be categorized as stable (gradually/progressive) or unstable (sudden/catastrophic) [ 54 ]. The stress-strain response for samples fabricated with a triangle pattern is a stable (progressive) crashing. The curves exhibit similar evolutionary modes, which are divided into three consecutive phases: (i) initially a linear elastic deformation zone; (ii) a stress plateau (initial peak force) with overlapped stress fluctuations in which the first collapses are created at critical nodes (stress concentration points), which may be thickness variations or corners; the collapsing mechanism is sustained and the stress significantly drops due to cell walls buckling and developing a significantly geometrical change at the critical nodes; (iii) gradual strain hardening due to densification (inner cellular structure walls come in contact). From Fig. 5, it is evident that the crush response is more sensitive to the sample wall thickness. For samples with a 6mm wall thickness, the crushing of the cell wall begins with a decrease in stress accompanied by noticeable plastic deformation. After that the stress increases steeply as increasing strain, presenting an ideal progressive deformation. The corresponding photographic images attached for this experiment reveal that the crushing response is stimulated by elastic wall bending of cells at a transverse array of cells, whereby the failure mechanisms and plastic deformation advance gradually. These samples exhibit a steep peak at a high stress level, followed by a slight decrease in stress, which is then followed by a zone of strain hardening, which had the highest sustained stress at the stress-strain response. In contrast, the strain is increased for samples of 1.2 mm wall thickness. The collapse mechanism is noticeable at the outer supporting wall thickness, which results in a weaker structure. The crushing response is triggered by the bending of elastic outer supporting wall and walls of cells at a horizontal array, whereby the failure mechanisms and plastic deformation progresses at a low-stress value with a rounded peak. In the last hardening zone, cell walls start to rotate around plastic points formed in the triangular structure, resulting in increased contact surface among neighboring walls, and creating a further phase of load transfer. Among all triangle pattern samples for PA 12 seen in Fig. 5a, The sample with 6 mm wall thickness and 85% infill presents the highest, longest, and most stable plateau zone in which only a few stress variations are observed. The corresponding photos reveal that the elements of the triangle structure are well bonded at triangle corners, which provides a strong structure to prevent sudden crushing of inclined bonds through elastic buckling, thus no critical drops in load are spotted. It is also evident from photos that the vertical members (cell walls) of the triangle structure fold inward and outward without any tears at the nodes of the structure. This change to a structure dominated by bending and stretching is reflected, in the stress-strain curves, by a steep increase in hardening modulus at the commencement of densification[ 55 ]. The stress-strain curves and deformation series of CF/PA triangle pattern samples are shown in Fig. 5b. The stress-strain responses of all CF/PA specimens and the corresponding recorded images (see Fig. 5b) show fewer stress fluctuations with a small load drop through the crushing phase and the collapse processes of the CF/PA triangle structures are relatively similar to their PA counterparts. However, slight differences are observed for the triangle sample of 70% infill and 6mm wall thickness, where crushing stress/a shear band is formed at a strain of about 7% (see Fig. 5b). Compared to the corresponding PA structure, this sample is the only CF/PA sample to demonstrate an initial crushing at a lower stage of strain, while the other samples start crushing almost at the same strain as the PA samples. In the crushing zone, the occurrence of the outward fold in the lateral direction of cell walls and outer support wall along with the lower composite ductility of CF/PA may have caused the early crushing at the interface between the angled and vertical walls, which, in turn, resulted in a quick fold of the sample structure of the type previously reported [ 56 ]. Finally, the phenomenon of strain localization is the cause for the significant drop of stress by a compression load and is not seen for the pure PA specimens, which crush uniformly (see Fig. 5a). Moreover, the higher amount of porosity of inter-bead in the CF/PA structure further promotes the early onset of failure. One of the new demanded industrial applications of 3D printing is sheet metal forming stamps. To design rapid and lightweight structures, it is necessary to select the proper printing parameters to enhance the specific energy absorption capacity. The crashworthiness factors of the 3D printed PA with different printing parameters under compression force are shown in Fig. 6. These factors include Initial peak force (IPF), Energy absorption (EA), Specific energy absorption (SEA), and Crushing force efficiency (CFE) for all triangle pattern samples of PA and CF/PA that are tested under compression stress. The equivalent compression strain (δd) is the strain at the beginning of the densification phase for each sample. According to Fig. 6, the IPF of all CF/PA lattices is greater than that of their PA counterparts. This demonstrates that the inclusion of chopped carbon fibers enhances the compression response. Figure 6a also demonstrates that the IPF of all samples is more significantly affected by the sample wall thickness than the infill percentage, which can be explained by the fact that the wall thickness provides outer rigidity for the sample, restricting the easy stretching and offering higher resistance under axial compression. Since outer rigidity is absent in the small wall thickness samples, their IPFs were found to be considerably smaller than those of thicker outer walls. For instance, when the sample is only 85% infill and with the highest wall thickness (6 mm), it possesses a larger IPF (27.39 KN) than that of a sample having 100% infill and 6 mm wall thickness (IPF = 27.21 KN). On the other hand, samples with a low wall thickness have the lowest IPF among all triangle pattern samples examined here, even if the sample has a 100% infill, as the PA samples with 1.2 mm wall thickness and 70, 85 and 100% infill have the lowest IPFs: 19.10, 21.51 and 21.95 KN, respectively. It can be concluded that the infill percentage slightly affects IPF when the wall thickness is the same. As shown in Fig. 6a, EA exhibits similar patterns. EA significantly improves when the sample outer walls are thicker and the infill percentage remains constant. For example, the sample with only 85% infill and 6 mm wall thickness also has the highest EA (3657.03 J), like its IPF for PA. The infill percentage also has a minor influence on energy absorption in this regard. So, the lowest EA, 2156.74 J, is indicated in the sample with a thinnest wall of 1.2 mm and with the highest infill percentage of 100%. SEA is a crucial factor for assessing the crashworthiness of a 3D-printed lightweight product, which represents the structural capacity of EA divided by mass unit. Figure 6a shows that the wall thickness factor outperforms all other crashworthiness factors in SEA terms due to its ability to provide the structure with a stable and uniform crashing response. The structure’s outward global deformation prevents the early onset of crashing at the interfaces, in contrast to specimens with thick walls. The presence of a substantial amount of vertical wall thickness inhibits excessive straining. It is preferable to appropriately increase the wall thickness to obtain a better capacity for SEA. The triangle pattern permits acceptable balance between the absorbed energy and stiffness characteristics which are usually antagonistic. The SEA of the triangle pattern drops around 70% with the amalgamation of CF in PA, due to the creation of a shear band by compressing PA with CF reinforcement. Figures 6a and 7b also demonstrate that the PA specimens exhibit a greater SEA than the CF/PA specimens. This may be due to the greater ductility of PA material in comparison to CF/PA, resulting in an increased ability to absorb energy through plastic dissipation [ 57 ]. CFE is another essential crashworthiness factor, which indicates the stability and uniformity of the collapsing force throughout loading. A high CFE may minimize the unwanted potential damage and scattered acceleration for the product structure. The experimental responses in Fig. 6a and Fig. 6b show that when the wall thickness is set to 6 mm, the infill percentage has little influence on the CFE of the 3D-printed PA. When the infill percentage is 70%, 85% or 100%, the triangle pattern with a wall thickness of 1.2 mm possesses a smaller CFE than that with a 3.6 mm wall thickness. 3.1.2 Rectilinear pattern samples The axial collapsing characteristic of the rectilinear pattern is usually stable for some samples, while for others, it is divided into two phases, the first phase is governed by the material elasticity until the peak and the load drops suddenly in the second phase, which is categorized as unstable (catastrophic) crushing. The stress-strain curves and collapsing behavior of both collapsing characteristics are common in the initial phase, there is an elastic deformation region (1) until the first peak stress is attained (2), followed by a sudden onset of collapse and a sharp drop in load (stress) (3). The stress-strain graphs for specimens that experience catastrophic crashing end at this point, while those that undergo progressive crashing maintain a constant stress level (4). In the final stage, sample densification increases the load due to the folding of sample walls. Figure 7 displays photographic images of each crushing phase. Figure 7 shows the nominal stress-strain of rectilinear PA and CF/PA structure under a compression load, along with pictures taken at different load stages. The stress-strain charts of PA and CF/PA patterns present similar behavior, and there are no considerable variances among the results of 70, 85, and 100% infill, confirming the infill percentage-independent compressive results of the rectilinear pattern of the same base material and relative density [ 58 ]. Beyond a first linear elastic, all samples present a well-known yield point, after that a considerable drop of stress occurs, owing to the commencement of walls buckling, As depicted in the photographic images, sample densification commences at 30–40% strain when the bent walls come in contact, resulting in a sharp rise in compressive stress along with increasing strain [ 55 ]. The images captured in Fig. 7 indicate that the buckling of the rectilinear structure is accompanied by lateral sliding of the outer walls for some specimens. In contrast, the predominant folding mode is bulging, which appears to initiate lateral expansion over compression stress and causes the inner pattern walls to bend inward. This is corroborated by the photographs shown in Fig. 7, where some specimens with low infill percentages exhibit a larger cross-sectional area than others after complete densification. It is observed that the peak at approximately 45% strain for specimens with low infill density structure may be attributed to temporary wall densification [ 59 ]. Figure 8 shows the crashworthiness factors (IPF, EA, SEA, CFE) calculated from the stress-strain responses. Despite the rectilinear pattern being slightly stronger than the triangle pattern, the crushing mechanism was more stable for the triangle pattern than for the rectilinear pattern, especially at low infill percentage and small wall thickness. As inferred from the captured images in Fig. 8, the wall thickness has a significant impact on the sliding effect of samples, while the deformation resistance slightly depends on the infill percentage. The sample of 70% infill and 1.2 mm outer wall thickness exhibits almost the lowest IPF (13 and 1875 KN) and EA (1252 and 196 J) for PA12 and CF/PA samples, respectively. The triangle is stronger than the rectilinear pattern due to the separation of the internal structure of the rectilinear pattern and the easy occurrence of sliding for a small wall thickness rectilinear sample. Considerable sliding effect and high deformation resistance (large height after releasing the load) appeared in samples of 100% infill and 1.2 mm wall thickness, so samples of only 70% infill and 6 mm wall thickness have a stable and uniform bulking without noticeable sliding. The sample of 85% infill and 6 mm wall thickness has the highest IPF (27.39 and 28 KN) and EA (3657.03 and 3800 J) for PA12 triangle and rectilinear patterns, respectively. As shown in Fig. 8b, the CF/ PA rectilinear samples exhibit significantly higher IPFs than the PA12 samples. This pattern is consistent with expectations, and this can be illustrated by the fact that the short carbon fibres are loaded at their stronger stretching deformation mode under compression as some fibres are parallel to the direction of compression. Otherwise, the CF/PA specimens exhibit a high standard of inter-bead porosity owing to the unstable flow of CF/PA melt from the nozzle during the printing process, resulting in lower density and reduced stiffness. It is also observed that the high porosity in CF/PA may be responsible for the inconsistent behaviors observed in the stress-strain results among different specimens. Moreover, Fig. 8 shows that the IPF is only slightly affected by the infill pattern. This was anticipated since all pattern walls undergo uniaxial compression during the initial elastic deformation phase, regardless of the chosen geometric pattern. We noticed from Fig. 8 that the sample of 100% infill exhibits high IPF for both the PA and CF/PA, while the rectilinear pattern presents the lowest IPF for both materials. These variations can be explained by differences in the buckling strength of the samples, which can be influenced by factors such as specimen height, internal pattern and outer wall thickness, as well as infill geometry and percentage. The compression strengths of the PA samples are normally lower than those of CF/PA samples owing to the lower IPF of the PA specimens, which restricts the strength of the pattern walls and therefore decreases EA of the structure. Figure 8 reveals that the PA sample of 85% infill, 6 mm wall thickness and rectilinear pattern has superior SEA compared to all other triangle and rectilinear samples. The highest value of CFE for all triangle and rectilinear samples was observed in the sample of 70% infill and 6 mm wall thickness, which has a stable collapsing force, less unwanted scattered acceleration, and less potential damage. 3.2 Impact 3.2.1 Triangle pattern samples Table 7 lists the average impact strength test results for triangular pattern nylon specimens and carbon fiber reinforced nylon samples. To better understand the relationships between the specified ranges of printing parameters and energy absorption/impact strength, a diagrammatic representation of the test results is shown in Figure 9. The following section explains the significant influences of printing parameters on the impact behaviors of 3D printed specimens. The results provided in Table 7 and Fig. 9 demonstrate that wall thickness significantly influenced the impact damage resistance with a noticeable anisotropy, especially in the state of higher wall thickness. While not as expected, infill percentage had less of an effect on impact strength as compared to wall thickness. Table 7 Average impact test results of Tringle PA 12 and CF/PA specimens. Triangle PA 12 samples Breaking Energy \({E}_{T}\) (J) Impact resistance (J/m) Impact strength \({E}_{c}\) (kJ/m2) 100%, 6 mm 0.209 16.25316834 1.573394685 70%,6 mm 0.198 15.39885321 1.490692355 85%,6 mm 0.204 15.83512571 1.532925893 100%,1.2 mm 0.156 12.09302326 1.178657237 70%,1.2 mm 0.17 13.17829457 1.276966528 70%,3.6 mm 0.412 32.03732504 3.1225463 100%,3.6 mm 0.42 32.6848249 3.154905879 85%,1.2 mm 0.487 37.89883268 3.658188483 85%,3.6 mm 0.538 42.03125 4.057070463 PA/ CF 100%, 6 mm 1.46 114.36225 9.222762097 70%,6 mm 1.45 113.28125 9.135584677 85%,6 mm 1.45 113.55113 9.157349194 100%,1.2 mm 0.677 52.890625 4.300050813 70%,1.2 mm 0.384 31.47540984 2.459016393 70%,3.6 mm 1.37 107.03125 9.070444915 100%,3.6 mm 0.993 77.578125 6.46484375 85%,1.2 mm 0.499 39.29133858 3.220601523 85%,3.6 mm 0.755 58.52713178 4.83695304 The influence of wall thickness on the impact resistance varied between samples due to infill percentage. In the case of samples with a high infill percentage, impact loading was increased as the crack propagation was restricted by infill material. The crack propagates through the sharp corners of the triangle pattern after overcoming the wall thickness. The crack is restricted initially by the wall thickness and then by the infill. On the other hand, higher wall thickness tends to promote impact resistance. This can be understood by considering that by increasing the wall thickness, less infill layers were needed for total sample thickness, thus the number of bonds among layers (which is regarded as a failure initiation) was reduced, and impact damage resistance improved (Fig. 9). The increase was even higher for PA/CF-based specimens. For the specimen of initial 1.2 mm wall thickness and 70% infill, the impact strength was 2.46 kJ/m 2 , while the strength of the 6 mm wall thickness and 100% infill specimen was the highest of all PA and PA/CF specimens, reaching 9.22 kJ/m 2 . Although there are some variances in impact strength responses, all 3D printed specimens have a very similar brittle nature of the crack propagation. Infill percentage has no remarkable effect on the given Charpy impact strength. Specimens with a high wall thickness have only a slightly higher strength. Interestingly, it can be concluded that a higher content of fiber has a positive impact on the Charpy impact damage resistance. 3.2.2 For rectilinear pattern samples Table 8 and Fig. 10 clarify the average impact strength for the 3D-printed rectilinear pattern samples. The responses demonstrated that the infill percentage significantly influences the impact characteristics of the 3D-printed specimens. The variance in impact strength of tested specimens is due to the differences in wall thickness and infill percentage. Table 8 depicts the impact results of the rectilinear pattern PA12 and CF/PA material. More specifically, it is clearly observed that the samples with a high infill percentage have the best characteristics in terms of impact strength. In contrast, wall thickness has a small effect. These analyses were in reasonable accordance with the responses of 3D printed specimens listed in Table 8. For instance, the PA 12 sample with the highest infill percentage (100%) and medium wall thickness of 3.6 mm possesses the highest impact resistance of 3.365182381 kJ/m 2 . Table 8 Average impact test results of Rectilinear PA 12 and CF/PA specimens. Rectilinear PA 12 samples Breaking Energy \({E}_{T}\) (J) Impact resistance (J/m) Impact strength \({E}_{c}\) (kJ/m2) 100%,6 mm 0.207 16.11293424 1.559819265 70%,6 mm 0.203 15.77311577 1.526923115 85%,6 mm 0.201 15.58324191 1.50854218 100%,1.2 mm 0.41 31.85703186 3.083933384 70%,1.2 mm 0.317 25.15873016 2.452117949 100%,3.6 mm 0.448 34.72868217 3.365182381 85%,1.2 mm 0.371 28.75968992 2.776031846 70%,3.6 mm 0.347 27.00389105 2.60655319 85%,3.6 mm 0.454 35.3858145 2.726179853 PA/ CF 100%,6 mm 1.45 113.97845 9.191810484 70%,6 mm 1.44 113.11682 9.122324194 85%,6 mm 1.44 113.01783 9.114341129 100%,1.2 mm 1.22 94.42724458 7.868937049 70%,1.2 mm 0.395 30.859375 2.554584023 100%,3.6 mm 0.955 75.19685039 6.163676262 85%,1.2 mm 0.469 35.80152672 2.98346056 70%,3.6 mm 1.117 87.265625 6.98125 85%,3.6 mm 0.28 22.95081967 1.712747737 The impact strength increased significantly for rectilinear pattern PA/CF specimens. A specimen of 100% infill and 1.2 mm wall thickness had an impact strength of 7.868937049 kJ/m 2 , while the strength of a 70% infill and 6 mm wall thickness specimen was the highest of all rectilinear pattern PA12 and PA/CF specimens, reaching 9.191810484 kJ/m 2 . Wall thickness has no noticeable influence on the given Charpy impact strength. There is only a slightly higher strength for specimens with a high infill percentage. Finally, it can be concluded that a chopped carbon fiber has a positive influence on the Charpy impact strength. 4 Conclusion In this research project, we tested the EA characteristics of AM PA12 and CF/PA lattices under compression and impact loading. Two different patterns (triangle and rectilinear) were 3D fabricated via SLS and FDM techniques. Selective Laser Sintering (SLS) was utilized to print NYLON (PA 12) samples from its initial form as powder, while Fused Deposition Modeling (FDM) was applied to produce CF/PA samples from its initial form as filament. CF/PA Filament consists of 80% PA and 20% chopped carbon fiber. The impact of strain-rate on mechanical response characteristics of AM samples subjected to compression and impact loading were examined. The measured mechanical characteristics of both triangle and rectilinear patterns of CF/PA were compared to those of PA at three levels of wall thickness (1.2, 3.6, 6 mm) and infill percentages (70, 85 and 100%) for each printed specimen. Rectilinear 3D fabricated samples are mechanically weaker than Triangle samples, so they are highly vulnerable to transverse plastic cracking at the outer wall of the sample. Triangle samples have an excellent bonding structure; thus, they have acceptable mechanical properties. Under compression, the stress-strain responses of all CF/PA specimens present fewer stress fluctuations with a small load drop through the crushing phase, while the collapse processes of the CF/PA are relatively similar to their PA counterparts. The crush response is more sensitive to the sample wall thickness. For the 6 mm wall thickness samples, the cell wall crushing commences with a drop in stress with noticeable plastic deformation, then the stress increases steeply as increasing strain, presenting an ideal progressive deformation. Among all triangle pattern samples for PA 12, the 6 mm wall thickness and 85% infill sample exhibits the highest and most stable plateau zone. The bonding at the triangle corners provides a strong structure to resist sudden crushing of inclined bonds through elastic buckling. The walls of the triangle structure fold inward and outward without any tears at the nodes of the structure. The crushing of CF/PA triangle samples commences almost the same as PA samples, while the CF/PA triangle sample of 70% infill and 6 mm wall thickness onset crushing at a strain of approximately 7%. Compared to PA structure, this is the only sample that demonstrated an initial crushing at a lower stage of strain. The buckling of the rectilinear structure is associated with lateral sliding of the outer walls to bend outwards with tears at the nodes of the structure. The stress-strain chart of the PA and CF/PA rectilinear pattern reveals a similar behavior, and there are no significant variances among the results of 70, 85, and 100% infill percentages. The IPFs of all triangle pattern samples are more significantly affected by the sample wall thickness than the infill percentage. Since outer rigidity is absent in the small wall thickness samples, the IPF was found to be much smaller than those with thicker outer walls. A sample of only 85% infill and with the highest wall thickness (6 mm) possesses a larger IPF (27.39 KN) than that of a sample with 100% infill and 6 mm wall thickness (27.21 KN). In contrast, samples with 1.2 mm wall thickness and 70, 85 and 100% infill have the lowest IPFs of 19.10, 21.51 and 21.95 KN, respectively. Similarly, for EA, the sample with only 85% infill and 6 mm wall thickness has the highest EA (3657.03 J) for PA. The infill percentage only has a minimal effect on energy absorption. So, the lowest EA, 2156.74 J, is observed in the sample with the thinnest wall of 1.2 mm and the highest infill percentage of 100%. The SEA of the triangle pattern drops around 70% with the amalgamation of CF in PA. It is also demonstrated that PA specimens have higher SEAs than their CF/PA counterparts. When the wall thickness is set to 6 mm, the infill percentage influences the CFE of the 3D-printed triangle pattern PA little. When the infill percentage is 70%, 85% or 100%, the triangle pattern with a wall thickness of 1.2 mm has a smaller CFE than that with a 3.6 mm wall thickness. The triangle pattern is stronger than the rectilinear pattern due to the separation of the internal structure of the rectilinear pattern and the easy occurrence of sliding for a small wall thickness rectilinear sample. The sample of 85% infill and 6 mm wall thickness has the highest IPF (27.39 and 28 KN) and EA (3657.03 and 3800 J) for PA12 triangle and rectilinear patterns, respectively. The rectilinear pattern sample of 70% infill and 1.2 mm outer wall thickness has almost the lowest IPF (13 and 1875 KN) and EA (1252 and 196 J) for PA12 and CF/PA samples, respectively. The PA sample of 85% infill, 6 mm wall thickness and a rectilinear pattern has a superior SEA compared to all other triangle and rectilinear samples. The highest value of CFE for all triangle and rectilinear samples was observed in the sample of 70% infill and 6 mm wall thickness. The impact strength of the triangle CF/PA sample of 1.2 mm wall thickness and 70% infill was 2.46 kJ/m 2 , while the strength of the 6 mm wall thickness and 100% infill specimen was the highest of all PA and PA/CF specimens, reaching 9.22 kJ/m 2 . The impact strength increased considerably for the rectilinear pattern PA/CF specimens. For the specimen with 100% infill and 1.2 mm wall thickness, the impact strength was 7.868937049 kJ/m 2 , while the strength of the specimen with 70% infill and 6 mm wall thickness was the highest of all rectilinear pattern PA 12 and PA/CF specimens, reaching 9.191810484 kJ/m 2 . Declarations Ethical Approval This study did not involve any human or animal subjects, data or tissue. Therefore, no ethical approval was required. The study followed the guidelines and standards of the International Organization for Standardization (ISO) and the American Society for Testing and Materials (ASTM) for 3D printing and testing of Nylon and CF/Nylon samples. Competing interests The authors declare that they have no competing interests of a financial or personal nature that could have influenced the design, execution or interpretation of this study. The authors have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. Authors’ contributions All authors contributed equally to this work. All authors conceived and designed the study. Mina and Khaled performed the 3D printing and testing of the samples. Mina and Sameh analyzed and interpreted the data. Sameh, Khaled and Tamer drafted and revised the manuscript. All authors read and approved the final manuscript. Funding In this work, we are pursuing support by the Science and Technology Development Fund (STDF). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. References D'Urso PS, Redmond MJ: A method for the resection of cranial tumours and skull reconstruction . Br J Neurosurg 2000, 14 (6):555-559. Lohfeld S, Barron V, McHugh PE: Biomodels of bone: a review . Ann Biomed Eng 2005, 33 (10):1295-1311. Sood AK, Equbal A, Toppo V, Ohdar RK, Mahapatra SS: An investigation on sliding wear of FDM built parts . CIRP Journal of Manufacturing Science and Technology 2012, 5 (1):48-54. Matsuzaki R, Ueda M, Namiki M, Jeong TK, Asahara H, Horiguchi K, Nakamura T, Todoroki A, Hirano Y: Three-dimensional printing of continuous-fiber composites by in-nozzle impregnation . Sci Rep 2016, 6 :23058. Caulfield B, McHugh PE, Lohfeld S: Dependence of mechanical properties of polyamide components on build parameters in the SLS process . Journal of Materials Processing Technology 2007, 182 (1-3):477-488. Rajpurohit SR, Dave HK: Effect of process parameters on tensile strength of FDM printed PLA part . Rapid Prototyping Journal 2018, 24 (8):1317-1324. Zhang X, Chen L, Mulholland T, Osswald TA: Effects of raster angle on the mechanical properties of PLA and Al/PLA composite part produced by fused deposition modeling . Polymers for Advanced Technologies 2019, 30 (8):2122-2135. Nagendra J, Prasad MSG: FDM Process Parameter Optimization by Taguchi Technique for Augmenting the Mechanical Properties of Nylon–Aramid Composite Used as Filament Material . Journal of The Institution of Engineers (India): Series C 2019, 101 (2):313-322. Williams CB, Cochran JK, Rosen DW: Additive manufacturing of metallic cellular materials via three-dimensional printing . The International Journal of Advanced Manufacturing Technology 2010, 53 (1-4):231-239. Jones R, Haufe P, Sells E, Iravani P, Olliver V, Palmer C, Bowyer A: RepRap – the replicating rapid prototyper . Robotica 2011, 29 (1):177-191. Fernandez-Vicente M, Calle W, Ferrandiz S, Conejero A: Effect of Infill Parameters on Tensile Mechanical Behavior in Desktop 3D Printing . 3D Printing and Additive Manufacturing 2016, 3 (3):183-192. Cooper K: Rapid prototyping technology: selection and application : CRC press; 2001. Pereira TF, Silva MAC, Oliveira MF, Maia IA, Silva JVL, Costa MF, Thiré RMSM: Effect of process parameters on the properties of selective laser sintered Poly(3-hydroxybutyrate) scaffolds for bone tissue engineering . Virtual and Physical Prototyping 2012, 7 (4):275-285. Tan K, Chua C, Leong K, Cheah C, Cheang P, Bakar MA, Cha SJB: Scaffold development using selective laser sintering of polyetheretherketone–hydroxyapatite biocomposite blends . 2003, 24 (18):3115-3123. Ho HCH, Cheung WL, Gibson IJI, research ec: Morphology and properties of selective laser sintered bisphenol a polycarbonate . 2003, 42 (9):1850-1862. Salazar A, Rico A, Rodríguez J, Segurado Escudero J, Seltzer R, Martin de la Escalera Cutillas F: Fatigue crack growth of SLS polyamide 12: Effect of reinforcement and temperature . Composites Part B: Engineering 2014, 59 :285-292. Van Hooreweder B, De Coninck F, Moens D, Boonen R, Sas P: Microstructural characterization of SLS-PA12 specimens under dynamic tension/compression excitation . Polymer Testing 2010, 29 (3):319-326. Mishra PK, Senthil P, Adarsh S, Anoop MS: An investigation to study the combined effect of different infill pattern and infill density on the impact strength of 3D printed polylactic acid parts . Composites Communications 2021, 24 . Singh R, Kumar R, Singh M, Preet P: On compressive and morphological features of 3D printed almond skin powder reinforced PLA matrix . Materials Research Express 2020, 7 (2). Wu D, Spanou A, Diez-Escudero A, Persson C: 3D-printed PLA/HA composite structures as synthetic trabecular bone: A feasibility study using fused deposition modeling . J Mech Behav Biomed Mater 2020, 103 :103608. Liu K, Li W, Chen S, Wen W, Lu L, Liu M, Zhou C, Luo B: The design, fabrication and evaluation of 3D printed gHNTs/gMgO whiskers/PLLA composite scaffold with honeycomb microstructure for bone tissue engineering . Composites Part B: Engineering 2020, 192 . Qin D, Sang L, Zhang Z, Lai S, Zhao Y: Compression Performance and Deformation Behavior of 3D-Printed PLA-Based Lattice Structures . Polymers (Basel) 2022, 14 (5). Zagidullin RS, Zezin NI, Rodionov NV: Improving the quality of FDM 3D printing of UAV and aircraft parts and assemblies by parametric software changes . IOP Conference Series: Materials Science and Engineering 2021, 1027 (1). Prayitno G, Imaduddin F, Ubaidillah, Arifin Z: Recent Progress of Fused Deposition Modeling (FDM) 3D Printing: Constructions, Parameters and Processings . IOP Conference Series: Materials Science and Engineering 2021, 1096 (1). Galeja M, Hejna A, Kosmela P, Kulawik A: Static and Dynamic Mechanical Properties of 3D Printed ABS as a Function of Raster Angle . Materials (Basel) 2020, 13 (2). Pollard D, Ward C, Herrmann G, Etches J: The manufacture of honeycomb cores using Fused Deposition Modeling . Advanced Manufacturing: Polymer & Composites Science 2017, 3 (1):21-31. Alam F, Shukla VR, Varadarajan KM, Kumar S: Microarchitected 3D printed polylactic acid (PLA) nanocomposite scaffolds for biomedical applications . J Mech Behav Biomed Mater 2020, 103 :103576. Liu H, He H, Peng X, Huang B, Li J: Three-dimensional printing of poly(lactic acid) bio-based composites with sugarcane bagasse fiber: Effect of printing orientation on tensile performance . Polymers for Advanced Technologies 2019, 30 (4):910-922. Gajdoš I, Slota JJTv: Influence of printing conditions on structure in FDM prototypes . 2013, 20 (2):231-236. Ngo TD, Kashani A, Imbalzano G, Nguyen KTQ, Hui D: Additive manufacturing (3D printing): A review of materials, methods, applications and challenges . Composites Part B: Engineering 2018, 143 :172-196. Papa I, Silvestri AT, Ricciardi MR, Lopresto V, Squillace A: Effect of Fibre Orientation on Novel Continuous 3D-Printed Fibre-Reinforced Composites . Polymers (Basel) 2021, 13 (15). Van Hooreweder B, Moens D, Boonen R, Kruth J-P, Sas P: On the difference in material structure and fatigue properties of nylon specimens produced by injection molding and selective laser sintering . Polymer Testing 2013, 32 (5):972-981. Monzon MD, Paz R, Ortega F, Chapela JA, Conde C: Process for reinforcing SLS parts by epoxy resin . Rapid Prototyping Journal 2015, 21 (3):322-328. Tang C, Liu J, Yang Y, Liu Y, Jiang S, Hao W: Effect of process parameters on mechanical properties of 3D printed PLA lattice structures . Composites Part C: Open Access 2020, 3 . Saenz F, Otarola C, Valladares K, Rojas J: Influence of 3D printing settings on mechanical properties of ABS at room temperature and 77 K . Additive Manufacturing 2021, 39 . Bartolomé E, Bozzo B, Sevilla P, Martínez-Pasarell O, Puig T, Granados X: ABS 3D printed solutions for cryogenic applications . Cryogenics 2017, 82 :30-37. Tymrak BM, Kreiger M, Pearce JM: Mechanical properties of components fabricated with open-source 3-D printers under realistic environmental conditions . Materials & Design 2014, 58 :242-246. Johnson GA, French JJJAiTI: Evaluation of infill effect on mechanical properties of consumer 3D printing materials . 2018, 3 (4):179. Suteja TJ, Soesanti A: Mechanical Properties of 3D Printed Polylactic Acid Product for Various Infill Design Parameters: A Review . Journal of Physics: Conference Series 2020, 1569 (4). Polyamide (PA12) for Industrial 3D Printing: EOS GmbH [https://www.eos.info/en/additive-manufacturing/3d-printing-plastic/sls-polymer-materials/polyamide-pa-12-alumide ePA12-CF [https://www.esun3d.com/epa12-cf-product/] SLS Printer FORMIGA P 110 Velocis [https://www.eos.info/en/additive-manufacturing/3d-printing-plastic/eos-polymer-systems/formiga-p-110-velocis] Kananathan J, Samykano M, Kadirgama K, Ramasamy D, Rahman MM: Comprehensive investigation and prediction model for mechanical properties of coconut wood–polylactic acid composites filaments for FDM 3D printing . European Journal of Wood and Wood Products 2021, 80 (1):75-100. Li S, Song Y, Song Y, Shi J, Liu L, Wei X, Guo QJC: Carbon foams with high compressive strength derived from mixtures of mesocarbon microbeads and mesophase pitch . 2007, 45 (10):2092-2097. Ender-3 Software& Firmware Download - Creality 3D Printer [https://www.creality.com/pages/download-ender-3?spm=..product_ce00868d-efe2-4fa8-9168-240e7c3b3cd1.nav_link_store_1.1] Maran JP, Manikandan SJD, Pigments: Response surface modeling and optimization of process parameters for aqueous extraction of pigments from prickly pear (Opuntia ficus-indica) fruit . 2012, 95 (3):465-472. Danbaba N, Nkama I, Badau MHJIJoFS, Engineering N: Application of response surface methodology (RSM) and central composite design (CCD) to optimize minerals composition of rice-cowpea composite blends during extrusion cooking . 2015, 5 (1):40-52. Ayutsede J, Gandhi M, Sukigara S, Ye H, Hsu C-m, Gogotsi Y, Ko FJB: Carbon nanotube reinforced Bombyx mori silk nanofibers by the electrospinning process . 2006, 7 (1):208-214. Xie Y, Chen J, Zhao H, Huang F: Prediction of the fiber diameter of melt electrospinning writing by kriging model . Journal of Applied Polymer Science 2022, 139 (21). International A: Standard test method for compressive properties of rigid plastics : ASTM International; 2010. Zhang L, Feih S, Daynes S, Chang S, Wang MY, Wei J, Lu WFJAM: Energy absorption characteristics of metallic triply periodic minimal surface sheet structures under compressive loading . 2018, 23 :505-515. Testing AASf, Materials: ASTM D6110-18: standard test method for determining the charpy impact resistance of notched specimens of plastics . In . : ASTM International West Conshohocken; 2018. Wang X-T, Wang B, Li X-W, Ma LJIJoMS: Mechanical properties of 3D re-entrant auxetic cellular structures . 2017, 131 :396-407. Hull DJCs, technology: A unified approach to progressive crushing of fibre-reinforced composite tubes . 1991, 40 (4):377-421. Zhang Y, Zong Z, Liu Q, Ma J, Wu Y, Li QJM, Design: Static and dynamic crushing responses of CFRP sandwich panels filled with different reinforced materials . 2017, 117 :396-408. Liu X, Wada T, Suzuki A, Takata N, Kobashi M, Kato MJM, Design: Understanding and suppressing shear band formation in strut-based lattice structures manufactured by laser powder bed fusion . 2021, 199 :109416. Arao Y, Taniguchi N, Nishiwaki T, Hirayama N, Kawada HJJoMS: Strain-rate dependence of the tensile strength of glass fibers . 2012, 47 (12):4895-4903. Kumar S, Ubaid J, Abishera R, Schiffer A, Deshpande VJAam, interfaces: Tunable energy absorption characteristics of architected honeycombs enabled via additive manufacturing . 2019, 11 (45):42549-42560. Andrew JJ, Verma P, Kumar SJM, Design: Impact behavior of nanoengineered, 3D printed plate-lattices . 2021, 202 :109516. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 03 Jun, 2023 Reviewers invited by journal 01 Jun, 2023 Editor assigned by journal 29 May, 2023 First submitted to journal 29 May, 2023 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-2948690","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":206052706,"identity":"6f2d4dcd-1ca9-4ec0-af96-55b705de1779","order_by":0,"name":"mina adel hanna","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIie2PsUrEQBCGNwpnc5A2YuErrM1WueRBbCYsXJoV7wGu2KvyClfI+QSCNtYjC9oEY7lwFlmE1NcKIk5OCy02Xim4X7HMwP/x7zAWCPxZeP9AhMV7SkO0wF0Vhu1o2it6B4V9KnftyGzHQSU+qp727Oz5OK4kIoyb7Koy1DJPT33K4UU921e8O1nWHSAka3lbF6TcT8+07wqrgBQTaas4Al9LgaRE2niV/EvJL+35BgEepWjcsMKTEnuluLaKISBmwv7SklDSkCJv6o7TlyQISy0wcEu8LN2LejOT1YN07lVnuWhK127mqVdhbMzx+1psk+CN9xy0P9Z8MBwIBAL/kg8mh2/BIK92MwAAAABJRU5ErkJggg==","orcid":"","institution":"Modern Academy of engineering","correspondingAuthor":true,"prefix":"","firstName":"mina","middleName":"adel","lastName":"hanna","suffix":""},{"id":206052707,"identity":"90e5d11a-8a69-4993-9eb4-69325fed75e1","order_by":1,"name":"Sameh Habib","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Sameh","middleName":"","lastName":"Habib","suffix":""},{"id":206052708,"identity":"c03df484-4ac5-4011-90d7-ffbed213f1f8","order_by":2,"name":"Khaled Abdelghany","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Khaled","middleName":"","lastName":"Abdelghany","suffix":""},{"id":206052709,"identity":"11d880ef-011d-4d56-b556-4831778e965f","order_by":3,"name":"Tamer Samir Mahmoud","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Tamer","middleName":"Samir","lastName":"Mahmoud","suffix":""}],"badges":[],"createdAt":"2023-05-17 16:29:37","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2948690/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2948690/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":38033817,"identity":"8fab4b17-0000-4030-94c4-e6f2df0afe67","added_by":"auto","created_at":"2023-06-05 15:12:54","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":773824,"visible":true,"origin":"","legend":"\u003cp\u003e(a) FORMIGA P 110 SLS for 3D printing PA 12 [42]. (b) Prepared PA 12 impact and compression samples with various configurations.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/5e2896f8fe25a0b67e91a35a.png"},{"id":38032084,"identity":"e1ff0644-b19a-4e2b-9f48-b6652b71177f","added_by":"auto","created_at":"2023-06-05 14:56:54","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":726501,"visible":true,"origin":"","legend":"\u003cp\u003e(a) CREALITY Ender-3 FDM for 3D printing Polyamide-CF [43]. (b) Prepared Polyamide-CF impact and compression samples with various configurations.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/35ed9420d091b5bbf903ed98.png"},{"id":38031058,"identity":"5fbb95bc-4817-4eb7-83a9-cc3165a5c327","added_by":"auto","created_at":"2023-06-05 14:48:54","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":192578,"visible":true,"origin":"","legend":"\u003cp\u003eGeometrical models of the 2D structure: triangle (top row), and rectilinear (bottom row) pattern, with infill density 70%, and 1.2-mm wall- thickness.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/6de9bac0472c867e4a19dc92.png"},{"id":38031051,"identity":"8c2ada59-18fc-45bb-bae9-2fce2486652f","added_by":"auto","created_at":"2023-06-05 14:48:54","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":59474,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Specimen for compression testing, (b) Specimen for impact testing, with infill density 70%, and 1.2-mm wall- thickness.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/134332630f0b2f6934252897.png"},{"id":38032086,"identity":"d98e658d-f4a3-471e-97b2-6f210abe8773","added_by":"auto","created_at":"2023-06-05 14:56:54","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":338608,"visible":true,"origin":"","legend":"\u003cp\u003eCompression behavior of the 3D printed samples: deformation pictures of samples and experimental apparatus at a different stage of strain is attached, Characteristic compression stress-strain curves of Triangle pattern for (a) PA12 and (b) CF/PA.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/7a15dbdd34ff09f05cc4ee1e.png"},{"id":38032083,"identity":"aba0b17a-6978-4a0a-af18-e827f1c8945c","added_by":"auto","created_at":"2023-06-05 14:56:54","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":293481,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical comparison of (a) PA12 and (b) CF/PA samples under compression: initial peek force (IPF), energy absorption (EA), specific energy absorption (SEA), and crushing force effeciency (CFE).\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/afdf42eed3fd7be19910c026.png"},{"id":38031054,"identity":"21366e07-6947-4656-acbb-be23e561654e","added_by":"auto","created_at":"2023-06-05 14:48:54","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":324429,"visible":true,"origin":"","legend":"\u003cp\u003eCompression behavior of the 3D printed samples: deformation pictures of samples and experimental apparatus at a different stage of strain is attached, Characteristic compression stress-strain curves of Rectilinear pattern for (a) PA12 and (b) CF/PA.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/51780a8f3707c86c9f52afb0.png"},{"id":38033022,"identity":"002fbde2-85ce-404a-8328-30836be50a76","added_by":"auto","created_at":"2023-06-05 15:04:54","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":299089,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical comparison of (a) PA12 and (b) CF/PA samples under compression: initial peek force (IPF), energy absorption (EA), specific energy absorption (SEA), and crushing force effeciency (CFE).\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/1f6d04635513879f6ccaf80c.png"},{"id":38033021,"identity":"46f13668-4308-4765-b24a-9fc9053047a0","added_by":"auto","created_at":"2023-06-05 15:04:54","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":215088,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical comparison of average maximum impact strength of Tringle PA 12 and CF/PA specimens.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/4bbd2bbedc57b1ea4af5e4bf.png"},{"id":38032089,"identity":"59944031-2faf-48ef-a9e9-57c605c5db66","added_by":"auto","created_at":"2023-06-05 14:56:54","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":256053,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical comparison of average maximum impact strength of Rectilinear PA 12 and CF/PA specimens.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/9ea20ce3543b7cf0be2d031e.png"},{"id":38033819,"identity":"0ba5cf3b-86d9-473e-8e1a-8a6158dd3990","added_by":"auto","created_at":"2023-06-05 15:13:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4766830,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2948690/v1/07db50b8-8e34-4f62-bbb8-74d8d8ce4214.pdf"}],"financialInterests":"","formattedTitle":"The effect of printing parameters on crushing behavior of 3D printed Nylon and CF/Nylon samples using Powder Bed Fusion and Material Extrusion techniques","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eTraditionally, solid freeform fabrication (SFF) approaches have been engaged in the rapid prototyping technique, primarily for visualization or kinematic functionality, such as in the case of a mechanism with moving parts. The development of rapid prototyping for industrial and engineering applications is a recent phenomenon PS D'Urso and MJ Redmond [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. As industrial companies have several ways to fabricate their products with much less time by depending on many manufacturing processes to hit the marketplace in time and maintain client demands [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. One of those major and higher-level techniques is Additive Manufacturing (AM) owing to the ability to fabricate finished (or at least near finished) products directly from the CAD version with no human interference [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. AM has more advantages and applications in different fields than the conventional technique. AM applications are widespread over numerous industries, including aerospace, customized parts, customer products, sports and lifestyle, bio-medical implant products, and automobiles[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The real significance of AM is that it can effectively fabricate complex structures and assist the engineers in ideally designing external and internal (print temperature, infill, and layer thickness) geometries and thereby effectively reduce costs and manufacturing time [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDifferent additive manufacturing technologies are based primarily on three categories of construction: sintering or melting of powder, deposition of filament and solidification of a liquid (resin) material. For each of these technologies, several different techniques have been innovated, like selective laser sintering (SLS), fused deposition modelling (FDM) or stereolithography (SLA)[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The patent expiration of these techniques, first for FDM, and later SLA and SLS, has stimulated curiosity regarding how to enhance and improving these techniques. The seed of this curiosity is the RepRap project, which aims to provide open source 3D printing designs to help construct 3D printer machines[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. One feature of this new methodology was to construct relatively small machines to be desktop 3D printers, developing a new industry presently termed \u0026lsquo;\u0026lsquo;desktop 3D printing.\u0026rsquo;\u0026rsquo; This involves sharing on the internet the successful and disruptive components for the design as well as the building instructions for constructing similar printers by anyone including a large percentage of the building components. This leads to an exponential increase in 3D printing users, new designs, and enhancements that have never been carried out by the patent owner. A considerable number of desktop 3D printing companies have been established from this project[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSelective Laser Sintering (SLS) is a crucial Additive Manufacturing (AM) technology that can create tissue-engineered scaffolds and intricate three-dimensional parts by fusing powdered material layer by layer to produce a final product[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. the SLS process uses a CO2 laser to selectively sinter thin layers of powder that are spread one above the other on a constructing bed. The building bed is on top of the rolling cylinder and goes down leaving a small gap that specifies the powder layer thickness. At the same time, the platform of the other feeders goes upwards to raise the powder to a sitting for collecting and spreading by the roller, filling the small gap, thereby spreading the first layer of powder. After that, the powder layer temperature is raised below the sinterisation point of the substance, known as the bed temperature of the part. Subsequently, scanning of the laser beam takes place on this layer, providing the required energy for selectively sintering the powder particles according to the cross-section contour of each object layer (computerized by a slicing program). After the sinterisation of this powder layer, another layer is spread on top of the existing one and this process is repeated according to the slicing program until the structure of the desired product is finished[\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This enables the creation of highly complex parts, avoiding the difficulties of conventional subtractive manufacturing forms, or processes with high tooling costs like injection molding. However, the sintering process of polyamide materials (which constitute 95 percent of polymer material used in AM[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]) produces porous, lightweight structures, but they have poor mechanical behaviors due to the small bonds and un-sintered powder[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] and thus have seen little use in major load-endurance applications. This is one of the biggest obstacles to 3D printing.\u003c/p\u003e \u003cp\u003ePolyamide 12, also known as nylon or PA12, is a commonly used material for Selective Laser Sintering (SLS) due to its eco-friendly nature and ease of sintering with a laser beam compared to other polymers[\u003cspan additionalcitationids=\"CR19 CR20\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In a powder form, Different commercial names are available for this product, such as PA 2200 (from EOS, Krailling, Germany), Duraform PA (from 3D-Systems, Rock Hill, SC, USA), or Nylon 12 (from Formlabs, Somerville, MA, USA). The mechanical behaviors of PA12 fabricated by SLS may differ roughly according to the SLS process variables and the anisotropy[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFDM has shown to be inexpensive, with the easiest printing and the most widespread technology of AM in marketplaces nowadays [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. FDM 3D printing technology mainly depends upon the concept of molten polymer filament extrusion. The thermoplastic polymer is molten at a relatively high temperature (200\u0026ndash;280\u003csup\u003eo\u003c/sup\u003eC), and then the melted plastic filament (thread) is fed from the movable nozzle via a knurled feeder onto the heated bed, which is usually made from glass or aluminum[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The filament is heated to semiliquid state and moved in both horizontal and vertical directions simultaneously to fabricate layer-by-layer deposition [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this regard, the FDM term is a Stratasys trademark, and this technique is equivalent to Fused Filament Fabrication (FFF), which was described in 2015 by ISO/ASTM as a material extrusion process[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. This technique can achieve several thermoplastic polymeric synthesis feedstocks using FFF for additive manufacturing (AM), increasing availability and use in the industry. Polylactide acid (PLA) has been extensively used as FDM material because of its excellent printability, eco-friendliness, and mechanical performance[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Moreover, PLA is commonly used as a biomedical material because of its biocompatibility and biodegradability [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Therefore, PLA has significant potential as a FFF building material and fabricated lattice structures used as synthetic bone scaffolds[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe mechanical properties of 3D-produced products are important in the field of rapid prototyping; thus, the prototype must have sufficient mechanical strength and proper surface quality for engaging in engineering purposes. Mechanical behaviors become important in the field of rapid manufacturing where the surface finish, strength, and stiffness must be suitable to meet operation and in-service loading requirements, and where they should be comparable to those produced using conventional manufacturing routes to make these processes competitive[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn one of their studies, Ngo et al[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] stated that AM technology builds a part by layers. Layers are fabricated by the machine and each layer is joined together to produce or create the final 3-D model. Ilaria et al. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] claimed that the potential of the technique is restricted by the lack of large-scale applications, the improvement of design building information, and the life-cycle cost of the 3D printed parts. Hooreweder et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] confirmed that 3D printed products need improved mechanical behavior if they are to be competitive with conventional manufacturing forms. Furthermore, Monzon [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] stated that plastic composites produced by AM \u0026ldquo;need to be more improved\u0026rdquo; as they have become primary parts in the aerospace and automotive industries.\u003c/p\u003e \u003cp\u003eA study by Can Tang et al. [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] revealed that both printing speed and printing temperature have a significant impact on elastic modulus and tensile strength. The elastic modulus and tensile strength increase with a high printing speed. F. Saenz et al. [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] have also examined Young\u0026rsquo;s Modulus, Yield Strength and Ultimate Strength of 3D printed ABS with input parameters of layer thickness, raster pattern and infill percentage using the Taguchi technique. There is proof that infill percentage, layer thickness and the interaction layer thickness-raster pattern cause variation in Young\u0026rsquo;s Modulus, Yield Strength and Ultimate Strength discussed by Bartolom\u0026eacute; et al [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Tymrak et al. [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e] found that tensile and yield strength, stiffness, and modulus elasticity of the part increase by increasing the infill density, although the increases in infill deposition rate decrease the tensile and yield strength of the part. The yield strength and tensile strength of 3D printed products are influenced by many infill designing parameters (infill deposition rate, infill density, and layer thickness) and the mechanical characteristics stated by Johnson et al. [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Suteja et al. [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] investigated this topic and found that the infill density increases the 3D printed product density. A higher density product has a higher yield and tensile strength. The smaller the gap, the greater the resistance moment. A higher moment resistance needs a higher break bending moment. Hence, it possesses higher flexural strength.\u003c/p\u003e \u003cp\u003eMost studies only engaged in a single material and a single technique to study the process parameters on the mechanical performance of the product and focused only on flexural, tensile and fracture properties, completely disregarding the differences in techniques and material properties and their effect on compressive strength and impact. So, the main goal of the current article is divided into two main parts. The first aim is using two different material types as: powders and filaments. While the second goal is applying advanced manufacturing technology of additive manufacturing as: FDM and SLS 3D techniques. Specifically, this study investigates the influence of process parameters of Nylon Polyamide (powders) and Nylon/CF (filaments) samples via FDM and SLS 3D techniques as: (i) building patterns, (ii) infill percentages, and (iii) wall-thicknesses on the mechanical characteristics especially impact and compressive strength.\u003c/p\u003e"},{"header":"2 Experimental procedure","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003e2.1 Materials\u003c/h2\u003e\n \u003cp\u003eIn this work, Polyamide 12 White powder, also known as Nylon (supplied by EOS GmbH, Germany) and Carbon Fiber Polyamide (Nylon) Filament of diameter 1.75 mm (supplied by ESUN, China) were used as feedstock. The whitish fine powder (PA 12) has acceptable balanced properties such as high strength and stiffness, biocompatibility confirmed by EN ISO 10993-1 and USP/level VI/121\u0026deg;C, good chemical resistance, and constant behavior for the long-term.\u003c/p\u003e\n \u003cp\u003eCarbon Fiber Nylon Filament consists of 80% nylon and 20% chopped carbon fiber. Carbon Fiber polyamide (Nylon) Filament has lower shrinkage, excellent thermal and chemical resistance, strong layer bonding, higher strength and rigidity and good toughness compared with ordinary nylon. According to the datasheet, the mechanical properties of PA 12 [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e] and carbon fiber reinforced Polyamide CF/PA filaments [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e] are summarized in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003e2.2 Specimen design and the 3D printing process\u003c/h2\u003e\n \u003cp\u003eSLS and FDM 3D printers were used to fabricate the NYLON (PA 12) and Polyamide-CF samples, respectively.\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eMechanical properties of Polyamide 12 powder and Polyamide-CF filament\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003ePolyamide 12 powder\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMechanical properties\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eValue\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnit\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTest Standard\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTensile Modulus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1700\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eISO 527-1/-2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTensile Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eISO 527-1/-2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexural Modulus, 23\u0026deg;C\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1500\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eISO 178\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexural Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eISO 178\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIzod Impact notched, 23\u0026deg;C\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ekJ/m\u0026sup2;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eISO 180/1A\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIzod Impact unnotched, 23\u0026deg;C\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ekJ/m\u0026sup2;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eISO 180/1U\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eShore D hardness (15s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eISO 868\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBall indentation hardness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eISO 2039-1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003ePolyamide-CF filament\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTensile Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGB/T 1040\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eElongation at Break\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGB/T 1040\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexural Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGB/T 9341\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexural Modulus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4363\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGB/T 9341\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIZOD Impact Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ekJ/㎡\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGB/T 1843\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e\n \u003ch2\u003e2.2.1 Selective Laser Sintering\u003c/h2\u003e\n \u003cp\u003eSelective Laser Sintering (SLS) 3D printer, FORMIGA P 110 (EOS Additive Technologies GmbH, Germany), was utilized to produce pure NYLON (PA 12) samples from its initial form as powder. EOS Parameter Editor, EOS RP Tools, PSW 3.6 software was used to adjust the printing parameters and extract the G-Code desired for the selective laser sintering (SLS) process. The SLS printing process parameters were based on the recommendation of the supplier (see Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). This SLS printer should meet all the minimum requirements for printing the samples for mechanical experiments. Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e presents the specification of the EOS FORMIGA P 110 SLS 3D printer [\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e]. Figure 1 presents the FORMIGA P 110 SLS Printer and impact and compression samples of the triangle and rectilinear pattern configurations with three levels of wall-thickness and infill percentages to investigate their energy absorption capabilities and compression properties.\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003econstant parameters during SLS printing process.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eParameters\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eValues\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLaser beam power\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25 W\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eScan speed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3000mm/s\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ebed temperature\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e169\u003csup\u003e◦\u003c/sup\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLayer thickness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026micro;m\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLaser spot size\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e~\u0026thinsp;0.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003especification of EOS SLS 3D printer.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eProperties\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSpecifications\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuilding volume\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e200 x 250 x 330 mm (7.9 x 9.8 x 13 in)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLaser type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCO\u003csub\u003e2\u003c/sub\u003e ; 30 W\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuilding rate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eup to 1.2 l/h\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLayer thickness (depending on material)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.06\u0026ndash;0.10\u0026ndash;0.12 mm (0.0024\u0026ndash;0.0039\u0026ndash;0.0047 in)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePrecision optics\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eF-theta lens, high-speed scanner\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eScan speed during build process\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eup to 5 m/s (16.4 ft/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePower supply\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16 A\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePower consumption\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003etypical 3 kW, maximum 5 kW\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDimensions (W x D x H)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,320 x 1,067 x 2,204 mm (51.97 x 42.01 x 86.77 in)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWeight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eapprox. 600 kg (1.323 lb)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv class=\"gridtable\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\n \u003ch2\u003e2.2.2 Fused Deposition Modeling\u003c/h2\u003e\n \u003cp\u003eFused Deposition Modeling (FDM) 3D printer, CREALITY Ender-3 (CREALITY-3D Printing, China), was utilized to produce Polyamide-CF samples from its initial form as filament. Ultimaker Cura, Ultimaker Cura 4.3 software was used to modify the printing parameters and obtain the G-Code required for the FDM process. The Fused Deposition Modeling (FDM) printing process parameters, as shown in Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, were chosen based on the recommendations of the materials supplier. The CREALITY Ender-3 FDM 3D printer has the necessary specifications to produce the specimens for mechanical testing. The features of this FDM printer are shown in Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e. Figure\u0026nbsp;2 presents the CREALITY Ender-3 FDM Printer and impact and compression samples. Before printing, the CREALITY Ender-3 3D printer needs to be calibrated manually. Calibration should be done in the all-moving axis (X-Y-Z) for printing samples at high accuracy. The alignment of the three axes with the horizontal ground axis should be 180\u0026deg; for high-precision printing. The hot table should also be adjusted before printing. The gap between the hot table and the nozzle should depend on the nozzle size, which can be measured with a feeler gauge. The nozzle distance should be uniform across the hot table. It is also important to make sure that the filament is extruded smoothly during printing without any irregularities or leakage on the printed table [\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]. For reducing the effect of factors not directly related to manufacture, it is essential to clean the printer nozzle after each 10 printed specimens as a result of deterioration of geometrical printing accuracy [\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e].\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003econstant parameters during FDM printing process.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eParameters\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eValues\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNozzle Diameter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.4 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLayer Height\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePerimeters Speed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25mm/s\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eInfill Speed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40 mm/s\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBed Temperature\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e90\u003csup\u003e◦\u003c/sup\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFirst Layer Temperature\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e240\u003csup\u003e◦\u003c/sup\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOther Layers Temperature\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e230\u003csup\u003e◦\u003c/sup\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFill Angles,\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45\u003csup\u003e◦\u003c/sup\u003e, -45\u003csup\u003e◦\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab5\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003especification of Ender-3 FDM 3D printer [\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eProperties\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSpecifications\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTechnology\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFDM\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePrint Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e220 x 220 x 250mm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNozzle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.4mm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax. Extruder temp.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e240◦C\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax. ped temp.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e120◦C\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax. Print Speed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e200mm/s\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax. Layer Resolution\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1mm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePrint Precision\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+/-0.1mm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWeight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10 kg\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFirmware\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMarlin\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv class=\"gridtable\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cp\u003eIn this work, 2D rectilinear and triangle structures were selected to study the compression properties of fabricated samples as shown in Fig. 3. Selection of these structures will simplify an overall assessment of the effect of the material properties and geometrical features on the mechanical properties. SLS and FDM were used to 3D print structures with NYLON-POLYAMIDE powder and CF/NYLON Nylon filament with chopped carbon fiber, respectively. The specimens were printed in the same direction to avoid variation in mechanical properties due to printing orientation, as the print direction affects the mechanical characteristics of the 3D printed samples.\u003c/p\u003e\n \u003cp\u003eSpecimens were designed on the SolidWorks 2018 software. Each sample was designed according to its parameters, including wall thickness, infill pattern and infill percentage, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e. Specimens were designed to open at one square face and close at another face to easily remove un-sintered powder material after finishing the SLS printing process. The specimen was printed in such a way that the closed square face was seated on the print bed, while the printing direction was up along the Z axis. Each specimen was designed according to ASTM standards for mechanical experiments. All designed samples were saved as STL Files and then copied to the slicing software using a flash drive. Printing parameters were adjusted by the slicer. Finally, G-code was generated from the slicer and transferred to the 3D printing machine.\u003c/p\u003e\n \u003cp\u003eThis experimental investigation was established based on selecting three controllable parameters from several 3D-printing factors. These parameters are infill percentage, infill pattern and wall thickness. This investigation involved three levels for infill percentage and wall thickness, and two levels for infill pattern.\u003c/p\u003e\n \u003cp\u003eResponse Surface Methodology (RSM) is a powerful statistical technique used to study the effects of multiple independent parameters on one or more responses. It is commonly used in experimental design as an effective way to optimize complex processes [\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e]. The RSM technique depends upon mathematical models such as linear, square polynomial functions, and others for fitting the experimental results that emerged from the designed experiment. Also, RSM is a statistical technique that can be used for model validation. To perform the required calculations, each independent parameter was coded at three levels, +\u0026thinsp;1, 0, and \u0026minus;\u0026thinsp;1, corresponding to the high-level, mid-level, and low-level, respectively [\u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e], as shown in Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e.\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab6\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003evariables with their code and levels for Central Composite- Face-centered Design.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"5\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eValues\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eParameters\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ecode\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+\u0026thinsp;1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eInfill percentage (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eX1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWall thickness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eX 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"5\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eInfill percentage (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eX 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWall thickness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eX 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003eThe experiment was prepared depending upon a Central Composite- Face-centered Design (CCF) with two variables at three levels for each triangle and rectilinear pattern. CCF has high efficiency and is practicable. It is commonly applied for engineering process optimization for its relatively small number of experimental requirements [\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e]. The required number of experiments for developing CCF is 2\u003csup\u003ek\u003c/sup\u003e\u0026thinsp;+\u0026thinsp;2 k\u0026thinsp;+\u0026thinsp;n\u003csub\u003ec\u003c/sub\u003e, where 2 k and n\u003csub\u003ec\u003c/sub\u003e are the number of axial and central points, respectively. A total of 28 experiments were generated in this work, including nine experiments for each triangle and rectilinear pattern and five replicates at the central point for each triangle and rectilinear pattern as listed in Table \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab7\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eDetails of test samples\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eS.No.\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eInfill percentage\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eInfill pattern\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWall thickness\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e26.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003e2.3 compressive testing\u003c/h2\u003e\n \u003cp\u003eIn this investigation, the printed specimens were subjected to a compression test to examine their deformation patterns and generate corresponding stress strain curves. From these curves, crashworthiness parameters such as energy absorption (EA), specific energy absorption (SEA), and crushing force efficiency (CFE), were obtained. As stated in ASTM D695 international standard, the compression test specimen should be shaped as a cylinder or a prism with diameter/side to length ratio of 2 to 1. Prism specimens should ideally have dimensions of 12.7 * 12.7 to 25.4 mm (0.50 * 0.50 to 1 in.), while cylinder specimens should have a diameter of 25.4 mm and a height of 12.7 mm [\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e]. A cube specimen shape was selected for this study with dimensions of 20*20*40 mm. The compression tests were carried out at the Ministry of Scientific Research National Institute for Standards (NIS) on a universal testing machine (UTM) equipped with a load cell of 100 kN according to ASTM D695 standard. The cube specimens were placed at the center between upper circular and lower rectangular hardened steel plates and the specimens were subjected to a constant pressure at a rate of 5 mm/min until they were compacted. The experiments took place at ambient temperature. Optical images of all test samples were taken by a CANON 600D DSLR camera. The image was captured at a rate of one frame per two seconds. The experiments were carried out on 3D printed cube specimens to evaluate the basic mechanical properties of the NYLON and CF/NYLON under uniaxial compression. The tests ended at fracture or a strain of 50% of the specimen\u0026rsquo;s structure. The EA of the specimen structures during the compression test was calculated from the area under the stress\u0026ndash;strain curve using the following formula (Eq.\u0026nbsp;(2))[\u003cspan class=\"CitationRef\"\u003e51\u003c/span\u003e]:\u003c/p\u003e\n \u003cp\u003eEA =\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\int }_{a}^{b}\\sigma .d\\epsilon\\)\u003c/span\u003e\u003c/span\u003e (1)\u003c/p\u003e\n \u003cp\u003eWhere \u0026sigma; is the compressive stress and the \u0026epsilon; represents the nominal strain. The calculation of \u0026sigma; and \u0026epsilon; are as follows: \u0026sigma;\u0026thinsp;=\u0026thinsp;F/A and \u0026epsilon;\u0026thinsp;=\u0026thinsp;\u0026delta;/H. F and \u0026delta; are the compressive force and displacement, which are measured during the compression test. A is the original cross section area and H is the height of the structure along the compression direction. The SEA is derived from EA and specimen weight.\u003c/p\u003e\n \u003cp\u003eSEA = \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\frac{EA}{m}\\)\u003c/span\u003e\u003c/span\u003e(2)\u003c/p\u003e\n \u003cp\u003eThe mean crushing force (MCF) and crushing force efficiency (CFE) were calculated as follows:\u003c/p\u003e\n \u003cp\u003eMCF = \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\frac{1}{{\\delta }_{d}} \\underset{0}{\\overset{{\\delta }_{d}}{\\int }}F{\\delta }_{d}\\)\u003c/span\u003e\u003c/span\u003e(3)\u003c/p\u003e\n \u003cp\u003eCFE = \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\frac{MCF}{IPF}\\)\u003c/span\u003e\u003c/span\u003e(4)\u003c/p\u003e\n \u003cp\u003eWhere IPF is initial peak force\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003e2.4 impact testing\u003c/h2\u003e\n \u003cp\u003eCharpy impact tests of 3D printed specimens were performed on a pendulum impact tester Zwick/Roell HIT (Zwick/Roell GmbH, Ulm, Germany) according to standard DIN EN ISO 179-1:2010 with standard notched test samples. The testing machine was equipped with a drop-weight hammer with 50 J impact energy. The measurements were obtained under specified working conditions with a 23\u0026deg;C room temperature and 50% relative humidity. The size of the impact specimens was designed according to ASTM D6110. with 12.7 mm \u0026times; 12.7 mm \u0026times; 127 mm as the maximum preferred notch dimension of specimens stated at the standard[\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe amount of energy lost during the specimen fracture is directly proportional to the difference in the original and final pendulum height. The total fracture energy is obtained by the following equation.\u003c/p\u003e\n \u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e$${E}_{T}=mg({h}_{o}-{h}_{f})\\pm 0.2J$$\u003c/div\u003e\n \u003cdiv class=\"EquationNumber\"\u003e5\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({E}_{T}\\)\u003c/span\u003e\u003c/span\u003e is the total energy, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(m\\)\u003c/span\u003e\u003c/span\u003e is the mass, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(g\\)\u003c/span\u003e\u003c/span\u003e is gravitational acceleration, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({h}_{o}\\)\u003c/span\u003e\u003c/span\u003e is the initial height and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({h}_{f}\\)\u003c/span\u003e\u003c/span\u003e is the final height. The impact strength (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({E}_{c}\\)\u003c/span\u003e\u003c/span\u003e) or absorbed energy per unit cross-sectional area (kJ/m2) is defined according to the standard ASTM D6110.\u003c/p\u003e\n \u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e$${E}_{c}=\\frac{{E}_{T}}{wt}$$\u003c/div\u003e\n \u003cdiv class=\"EquationNumber\"\u003e6\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere the specimen width and thickness are \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(w\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(t\\)\u003c/span\u003e\u003c/span\u003e, respectively. The losses of energy due to the air resistance and bearing friction were neglected because of their negligible contribution to the energy balance.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"3 Results and discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 Compression properties\u003c/h2\u003e\n \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e\n \u003ch2\u003e3.1.1 Triangular pattern samples\u003c/h2\u003e\n \u003cp\u003eThe experimental results revealed that the 3D-printing of triangle pattern PA12 and PA-CF materials with different printing parameters such as infill percentage (70, 85, 100%) and wall thickness in mm (1.2, 3.6, 6) exhibited slightly different distortion patterns and mechanical properties when subjected to compression and impact tests. Compression distortion behaviors for all samples were a combination of progressive folding and lateral shearing failures. Specimens were successfully SLS- and FDM-printed without any defects. Nonetheless, rectilinear 3D printed samples are mechanically weaker than triangle samples, as a result of the sensitive lateral shear behaviors of rectilinear samples [\u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e], causing them to be highly vulnerable to transverse plastic cracking at the outer sample surface. The triangle samples have an excellent bonding structure; thus, they have an acceptable mechanical property.\u003c/p\u003e\n \u003cp\u003eThe nominal stress-strain curves of PA12 and PA-CF printed with three different values of infill percentage and wall thickness for the triangular pattern under compression loading are presented in Fig. 5, along with photos captured at various loading stages. The equivalent compression stress is calculated as \u0026sigma;\u0026thinsp;=\u0026thinsp;F/A, where F is the equivalent compression load and A is the cross-sectional area of the sample, which is determined by A\u0026thinsp;=\u0026thinsp;L (length) \u0026times; W (width).\u003c/p\u003e\n \u003cp\u003eGenerally, the crushing characteristic of 3D fabricated specimens during compression can be categorized as stable (gradually/progressive) or unstable (sudden/catastrophic) [\u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e]. The stress-strain response for samples fabricated with a triangle pattern is a stable (progressive) crashing. The curves exhibit similar evolutionary modes, which are divided into three consecutive phases: (i) initially a linear elastic deformation zone; (ii) a stress plateau (initial peak force) with overlapped stress fluctuations in which the first collapses are created at critical nodes (stress concentration points), which may be thickness variations or corners; the collapsing mechanism is sustained and the stress significantly drops due to cell walls buckling and developing a significantly geometrical change at the critical nodes; (iii) gradual strain hardening due to densification (inner cellular structure walls come in contact).\u003c/p\u003e\n \u003cp\u003eFrom Fig.\u0026nbsp;5, it is evident that the crush response is more sensitive to the sample wall thickness. For samples with a 6mm wall thickness, the crushing of the cell wall begins with a decrease in stress accompanied by noticeable plastic deformation. After that the stress increases steeply as increasing strain, presenting an ideal progressive deformation. The corresponding photographic images attached for this experiment reveal that the crushing response is stimulated by elastic wall bending of cells at a transverse array of cells, whereby the failure mechanisms and plastic deformation advance gradually. These samples exhibit a steep peak at a high stress level, followed by a slight decrease in stress, which is then followed by a zone of strain hardening, which had the highest sustained stress at the stress-strain response.\u003c/p\u003e\n \u003cp\u003eIn contrast, the strain is increased for samples of 1.2 mm wall thickness. The collapse mechanism is noticeable at the outer supporting wall thickness, which results in a weaker structure. The crushing response is triggered by the bending of elastic outer supporting wall and walls of cells at a horizontal array, whereby the failure mechanisms and plastic deformation progresses at a low-stress value with a rounded peak. In the last hardening zone, cell walls start to rotate around plastic points formed in the triangular structure, resulting in increased contact surface among neighboring walls, and creating a further phase of load transfer.\u003c/p\u003e\n \u003cp\u003eAmong all triangle pattern samples for PA 12 seen in Fig.\u0026nbsp;5a, The sample with 6 mm wall thickness and 85% infill presents the highest, longest, and most stable plateau zone in which only a few stress variations are observed. The corresponding photos reveal that the elements of the triangle structure are well bonded at triangle corners, which provides a strong structure to prevent sudden crushing of inclined bonds through elastic buckling, thus no critical drops in load are spotted. It is also evident from photos that the vertical members (cell walls) of the triangle structure fold inward and outward without any tears at the nodes of the structure. This change to a structure dominated by bending and stretching is reflected, in the stress-strain curves, by a steep increase in hardening modulus at the commencement of densification[\u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe stress-strain curves and deformation series of CF/PA triangle pattern samples are shown in Fig.\u0026nbsp;5b. The stress-strain responses of all CF/PA specimens and the corresponding recorded images (see Fig.\u0026nbsp;5b) show fewer stress fluctuations with a small load drop through the crushing phase and the collapse processes of the CF/PA triangle structures are relatively similar to their PA counterparts. However, slight differences are observed for the triangle sample of 70% infill and 6mm wall thickness, where crushing stress/a shear band is formed at a strain of about 7% (see Fig.\u0026nbsp;5b). Compared to the corresponding PA structure, this sample is the only CF/PA sample to demonstrate an initial crushing at a lower stage of strain, while the other samples start crushing almost at the same strain as the PA samples. In the crushing zone, the occurrence of the outward fold in the lateral direction of cell walls and outer support wall along with the lower composite ductility of CF/PA may have caused the early crushing at the interface between the angled and vertical walls, which, in turn, resulted in a quick fold of the sample structure of the type previously reported [\u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e]. Finally, the phenomenon of strain localization is the cause for the significant drop of stress by a compression load and is not seen for the pure PA specimens, which crush uniformly (see Fig.\u0026nbsp;5a). Moreover, the higher amount of porosity of inter-bead in the CF/PA structure further promotes the early onset of failure.\u003c/p\u003e\n \u003cp\u003eOne of the new demanded industrial applications of 3D printing is sheet metal forming stamps. To design rapid and lightweight structures, it is necessary to select the proper printing parameters to enhance the specific energy absorption capacity. The crashworthiness factors of the 3D printed PA with different printing parameters under compression force are shown in Fig.\u0026nbsp;6. These factors include Initial peak force (IPF), Energy absorption (EA), Specific energy absorption (SEA), and Crushing force efficiency (CFE) for all triangle pattern samples of PA and CF/PA that are tested under compression stress. The equivalent compression strain (\u0026delta;d) is the strain at the beginning of the densification phase for each sample.\u003c/p\u003e\n \u003cp\u003eAccording to Fig. 6, the IPF of all CF/PA lattices is greater than that of their PA counterparts. This demonstrates that the inclusion of chopped carbon fibers enhances the compression response. Figure 6a also demonstrates that the IPF of all samples is more significantly affected by the sample wall thickness than the infill percentage, which can be explained by the fact that the wall thickness provides outer rigidity for the sample, restricting the easy stretching and offering higher resistance under axial compression. Since outer rigidity is absent in the small wall thickness samples, their IPFs were found to be considerably smaller than those of thicker outer walls. For instance, when the sample is only 85% infill and with the highest wall thickness (6 mm), it possesses a larger IPF (27.39 KN) than that of a sample having 100% infill and 6 mm wall thickness (IPF\u0026thinsp;=\u0026thinsp;27.21 KN). On the other hand, samples with a low wall thickness have the lowest IPF among all triangle pattern samples examined here, even if the sample has a 100% infill, as the PA samples with 1.2 mm wall thickness and 70, 85 and 100% infill have the lowest IPFs: 19.10, 21.51 and 21.95 KN, respectively. It can be concluded that the infill percentage slightly affects IPF when the wall thickness is the same.\u003c/p\u003e\n \u003cp\u003eAs shown in Fig.\u0026nbsp;6a, EA exhibits similar patterns. EA significantly improves when the sample outer walls are thicker and the infill percentage remains constant. For example, the sample with only 85% infill and 6 mm wall thickness also has the highest EA (3657.03 J), like its IPF for PA. The infill percentage also has a minor influence on energy absorption in this regard. So, the lowest EA, 2156.74 J, is indicated in the sample with a thinnest wall of 1.2 mm and with the highest infill percentage of 100%.\u003c/p\u003e\n \u003cp\u003eSEA is a crucial factor for assessing the crashworthiness of a 3D-printed lightweight product, which represents the structural capacity of EA divided by mass unit. Figure\u0026nbsp;6a shows that the wall thickness factor outperforms all other crashworthiness factors in SEA terms due to its ability to provide the structure with a stable and uniform crashing response. The structure\u0026rsquo;s outward global deformation prevents the early onset of crashing at the interfaces, in contrast to specimens with thick walls. The presence of a substantial amount of vertical wall thickness inhibits excessive straining. It is preferable to appropriately increase the wall thickness to obtain a better capacity for SEA. The triangle pattern permits acceptable balance between the absorbed energy and stiffness characteristics which are usually antagonistic.\u003c/p\u003e\n \u003cp\u003eThe SEA of the triangle pattern drops around 70% with the amalgamation of CF in PA, due to the creation of a shear band by compressing PA with CF reinforcement. Figures\u0026nbsp;6a and 7b also demonstrate that the PA specimens exhibit a greater SEA than the CF/PA specimens. This may be due to the greater ductility of PA material in comparison to CF/PA, resulting in an increased ability to absorb energy through plastic dissipation [\u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eCFE is another essential crashworthiness factor, which indicates the stability and uniformity of the collapsing force throughout loading. A high CFE may minimize the unwanted potential damage and scattered acceleration for the product structure. The experimental responses in Fig.\u0026nbsp;6a and Fig.\u0026nbsp;6b show that when the wall thickness is set to 6 mm, the infill percentage has little influence on the CFE of the 3D-printed PA. When the infill percentage is 70%, 85% or 100%, the triangle pattern with a wall thickness of 1.2 mm possesses a smaller CFE than that with a 3.6 mm wall thickness.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e\n \u003ch2\u003e3.1.2 Rectilinear pattern samples\u003c/h2\u003e\n \u003cp\u003eThe axial collapsing characteristic of the rectilinear pattern is usually stable for some samples, while for others, it is divided into two phases, the first phase is governed by the material elasticity until the peak and the load drops suddenly in the second phase, which is categorized as unstable (catastrophic) crushing. The stress-strain curves and collapsing behavior of both collapsing characteristics are common in the initial phase, there is an elastic deformation region (1) until the first peak stress is attained (2), followed by a sudden onset of collapse and a sharp drop in load (stress) (3). The stress-strain graphs for specimens that experience catastrophic crashing end at this point, while those that undergo progressive crashing maintain a constant stress level (4). In the final stage, sample densification increases the load due to the folding of sample walls. Figure\u0026nbsp;7 displays photographic images of each crushing phase.\u003c/p\u003e\n \u003cp\u003eFigure\u0026nbsp;7 shows the nominal stress-strain of rectilinear PA and CF/PA structure under a compression load, along with pictures taken at different load stages. The stress-strain charts of PA and CF/PA patterns present similar behavior, and there are no considerable variances among the results of 70, 85, and 100% infill, confirming the infill percentage-independent compressive results of the rectilinear pattern of the same base material and relative density [\u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e]. Beyond a first linear elastic, all samples present a well-known yield point, after that a considerable drop of stress occurs, owing to the commencement of walls buckling, As depicted in the photographic images, sample densification commences at 30\u0026ndash;40% strain when the bent walls come in contact, resulting in a sharp rise in compressive stress along with increasing strain [\u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e]. The images captured in Fig.\u0026nbsp;7 indicate that the buckling of the rectilinear structure is accompanied by lateral sliding of the outer walls for some specimens. In contrast, the predominant folding mode is bulging, which appears to initiate lateral expansion over compression stress and causes the inner pattern walls to bend inward. This is corroborated by the photographs shown in Fig.\u0026nbsp;7, where some specimens with low infill percentages exhibit a larger cross-sectional area than others after complete densification. It is observed that the peak at approximately 45% strain for specimens with low infill density structure may be attributed to temporary wall densification [\u003cspan class=\"CitationRef\"\u003e59\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eFigure\u0026nbsp;8 shows the crashworthiness factors (IPF, EA, SEA, CFE) calculated from the stress-strain responses. Despite the rectilinear pattern being slightly stronger than the triangle pattern, the crushing mechanism was more stable for the triangle pattern than for the rectilinear pattern, especially at low infill percentage and small wall thickness. As inferred from the captured images in Fig.\u0026nbsp;8, the wall thickness has a significant impact on the sliding effect of samples, while the deformation resistance slightly depends on the infill percentage. The sample of 70% infill and 1.2 mm outer wall thickness exhibits almost the lowest IPF (13 and 1875 KN) and EA (1252 and 196 J) for PA12 and CF/PA samples, respectively.\u003c/p\u003e\n \u003cp\u003eThe triangle is stronger than the rectilinear pattern due to the separation of the internal structure of the rectilinear pattern and the easy occurrence of sliding for a small wall thickness rectilinear sample. Considerable sliding effect and high deformation resistance (large height after releasing the load) appeared in samples of 100% infill and 1.2 mm wall thickness, so samples of only 70% infill and 6 mm wall thickness have a stable and uniform bulking without noticeable sliding. The sample of 85% infill and 6 mm wall thickness has the highest IPF (27.39 and 28 KN) and EA (3657.03 and 3800 J) for PA12 triangle and rectilinear patterns, respectively.\u003c/p\u003e\n \u003cp\u003eAs shown in Fig.\u0026nbsp;8b, the CF/ PA rectilinear samples exhibit significantly higher IPFs than the PA12 samples. This pattern is consistent with expectations, and this can be illustrated by the fact that the short carbon fibres are loaded at their stronger stretching deformation mode under compression as some fibres are parallel to the direction of compression. Otherwise, the CF/PA specimens exhibit a high standard of inter-bead porosity owing to the unstable flow of CF/PA melt from the nozzle during the printing process, resulting in lower density and reduced stiffness. It is also observed that the high porosity in CF/PA may be responsible for the inconsistent behaviors observed in the stress-strain results among different specimens.\u003c/p\u003e\n \u003cp\u003eMoreover, Fig.\u0026nbsp;8 shows that the IPF is only slightly affected by the infill pattern. This was anticipated since all pattern walls undergo uniaxial compression during the initial elastic deformation phase, regardless of the chosen geometric pattern. We noticed from Fig.\u0026nbsp;8 that the sample of 100% infill exhibits high IPF for both the PA and CF/PA, while the rectilinear pattern presents the lowest IPF for both materials. These variations can be explained by differences in the buckling strength of the samples, which can be influenced by factors such as specimen height, internal pattern and outer wall thickness, as well as infill geometry and percentage. The compression strengths of the PA samples are normally lower than those of CF/PA samples owing to the lower IPF of the PA specimens, which restricts the strength of the pattern walls and therefore decreases EA of the structure. Figure\u0026nbsp;8 reveals that the PA sample of 85% infill, 6 mm wall thickness and rectilinear pattern has superior SEA compared to all other triangle and rectilinear samples. The highest value of CFE for all triangle and rectilinear samples was observed in the sample of 70% infill and 6 mm wall thickness, which has a stable collapsing force, less unwanted scattered acceleration, and less potential damage.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 Impact\u003c/h2\u003e\n \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e\n \u003ch2\u003e3.2.1 Triangle pattern samples\u003c/h2\u003e\n \u003cp\u003eTable 7 lists the average impact strength test results for triangular pattern nylon specimens and carbon fiber reinforced nylon samples. To better understand the relationships between the specified ranges of printing parameters and energy absorption/impact strength, a diagrammatic representation of the test results is shown in Figure 9. The following section explains the significant influences of printing parameters on the impact behaviors of 3D printed specimens.\u003c/p\u003e\n \u003cp\u003eThe results provided in Table 7 and Fig. 9 demonstrate that wall thickness significantly influenced the impact damage resistance with a noticeable anisotropy, especially in the state of higher wall thickness. While not as expected, infill percentage had less of an effect on impact strength as compared to wall thickness.\u0026nbsp;\u003c/p\u003e\u0026nbsp;\u003ctable id=\"Tab9\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eAverage impact test results of Tringle PA 12 and CF/PA specimens.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eTriangle\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003ePA 12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003esamples\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBreaking Energy \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({E}_{T}\\)\u003c/span\u003e\u003c/span\u003e (J)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eImpact resistance\u003c/p\u003e\n \u003cp\u003e(J/m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eImpact strength \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({E}_{c}\\)\u003c/span\u003e\u003c/span\u003e (kJ/m2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%, 6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.209\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.25316834\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.573394685\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.198\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.39885321\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.490692355\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.204\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.83512571\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.532925893\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.09302326\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.178657237\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.17829457\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.276966528\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.412\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32.03732504\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.1225463\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32.6848249\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.154905879\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.487\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37.89883268\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.658188483\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.538\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e42.03125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.057070463\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003ePA/ CF\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%, 6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e114.36225\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.222762097\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e113.28125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.135584677\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e113.55113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.157349194\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.677\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e52.890625\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.300050813\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.384\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.47540984\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.459016393\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e107.03125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.070444915\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e77.578125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.46484375\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.499\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e39.29133858\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.220601523\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.755\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e58.52713178\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.83695304\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003eThe influence of wall thickness on the impact resistance varied between samples due to infill percentage. In the case of samples with a high infill percentage, impact loading was increased as the crack propagation was restricted by infill material. The crack propagates through the sharp corners of the triangle pattern after overcoming the wall thickness. The crack is restricted initially by the wall thickness and then by the infill. On the other hand, higher wall thickness tends to promote impact resistance. This can be understood by considering that by increasing the wall thickness, less infill layers were needed for total sample thickness, thus the number of bonds among layers (which is regarded as a failure initiation) was reduced, and impact damage resistance improved (Fig.\u0026nbsp;9).\u003c/p\u003e\n \u003cp\u003eThe increase was even higher for PA/CF-based specimens. For the specimen of initial 1.2 mm wall thickness and 70% infill, the impact strength was 2.46 kJ/m\u003csup\u003e2\u003c/sup\u003e, while the strength of the 6 mm wall thickness and 100% infill specimen was the highest of all PA and PA/CF specimens, reaching 9.22 kJ/m\u003csup\u003e2\u003c/sup\u003e. Although there are some variances in impact strength responses, all 3D printed specimens have a very similar brittle nature of the crack propagation. Infill percentage has no remarkable effect on the given Charpy impact strength. Specimens with a high wall thickness have only a slightly higher strength. Interestingly, it can be concluded that a higher content of fiber has a positive impact on the Charpy impact damage resistance.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\n \u003ch2\u003e3.2.2 For rectilinear pattern samples\u003c/h2\u003e\n \u003cp\u003eTable 8 and Fig. 10 clarify the average impact strength for the 3D-printed rectilinear pattern samples. The responses demonstrated that the infill percentage significantly influences the impact characteristics of the 3D-printed specimens. The variance in impact strength of tested specimens is due to the differences in wall thickness and infill percentage. Table 8 depicts the impact results of the rectilinear pattern PA12 and CF/PA material. More specifically, it is clearly observed that the samples with a high infill percentage have the best characteristics in terms of impact strength. In contrast, wall thickness has a small effect. \u0026nbsp;These analyses were in reasonable accordance with the responses of 3D printed specimens listed in Table 8. For instance, the PA 12 sample with the highest infill percentage (100%) and medium wall thickness of 3.6 mm possesses the highest impact resistance of 3.365182381 kJ/m\u003csup\u003e2\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\u003ctable id=\"Tab11\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eAverage impact test results of Rectilinear PA 12 and CF/PA specimens.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eRectilinear\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003ePA 12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003esamples\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBreaking Energy \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({E}_{T}\\)\u003c/span\u003e\u003c/span\u003e (J)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eImpact resistance\u003c/p\u003e\n \u003cp\u003e(J/m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eImpact strength \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({E}_{c}\\)\u003c/span\u003e\u003c/span\u003e (kJ/m2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.207\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.11293424\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.559819265\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.203\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.77311577\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.526923115\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.201\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.58324191\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.50854218\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.85703186\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.083933384\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.317\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.15873016\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.452117949\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.448\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34.72868217\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.365182381\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.371\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.75968992\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.776031846\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.347\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.00389105\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.60655319\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.454\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35.3858145\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.726179853\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003ePA/ CF\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e113.97845\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.191810484\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e113.11682\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.122324194\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e113.01783\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.114341129\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e94.42724458\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.868937049\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.395\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.859375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.554584023\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.955\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e75.19685039\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.163676262\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,1.2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.469\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35.80152672\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.98346056\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.117\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e87.265625\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.98125\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e85%,3.6 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.95081967\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.712747737\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003eThe impact strength increased significantly for rectilinear pattern PA/CF specimens. A specimen of 100% infill and 1.2 mm wall thickness had an impact strength of 7.868937049 kJ/m\u003csup\u003e2\u003c/sup\u003e, while the strength of a 70% infill and 6 mm wall thickness specimen was the highest of all rectilinear pattern PA12 and PA/CF specimens, reaching 9.191810484 kJ/m\u003csup\u003e2\u003c/sup\u003e. Wall thickness has no noticeable influence on the given Charpy impact strength. There is only a slightly higher strength for specimens with a high infill percentage. Finally, it can be concluded that a chopped carbon fiber has a positive influence on the Charpy impact strength.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"4 Conclusion","content":"\u003cp\u003eIn this research project, we tested the EA characteristics of AM PA12 and CF/PA lattices under compression and impact loading. Two different patterns (triangle and rectilinear) were 3D fabricated via SLS and FDM techniques. Selective Laser Sintering (SLS) was utilized to print NYLON (PA 12) samples from its initial form as powder, while Fused Deposition Modeling (FDM) was applied to produce CF/PA samples from its initial form as filament. CF/PA Filament consists of 80% PA and 20% chopped carbon fiber. The impact of strain-rate on mechanical response characteristics of AM samples subjected to compression and impact loading were examined. The measured mechanical characteristics of both triangle and rectilinear patterns of CF/PA were compared to those of PA at three levels of wall thickness (1.2, 3.6, 6 mm) and infill percentages (70, 85 and 100%) for each printed specimen.\u003c/p\u003e \u003cp\u003eRectilinear 3D fabricated samples are mechanically weaker than Triangle samples, so they are highly vulnerable to transverse plastic cracking at the outer wall of the sample. Triangle samples have an excellent bonding structure; thus, they have acceptable mechanical properties. Under compression, the stress-strain responses of all CF/PA specimens present fewer stress fluctuations with a small load drop through the crushing phase, while the collapse processes of the CF/PA are relatively similar to their PA counterparts. The crush response is more sensitive to the sample wall thickness. For the 6 mm wall thickness samples, the cell wall crushing commences with a drop in stress with noticeable plastic deformation, then the stress increases steeply as increasing strain, presenting an ideal progressive deformation.\u003c/p\u003e \u003cp\u003eAmong all triangle pattern samples for PA 12, the 6 mm wall thickness and 85% infill sample exhibits the highest and most stable plateau zone. The bonding at the triangle corners provides a strong structure to resist sudden crushing of inclined bonds through elastic buckling. The walls of the triangle structure fold inward and outward without any tears at the nodes of the structure. The crushing of CF/PA triangle samples commences almost the same as PA samples, while the CF/PA triangle sample of 70% infill and 6 mm wall thickness onset crushing at a strain of approximately 7%. Compared to PA structure, this is the only sample that demonstrated an initial crushing at a lower stage of strain.\u003c/p\u003e \u003cp\u003eThe buckling of the rectilinear structure is associated with lateral sliding of the outer walls to bend outwards with tears at the nodes of the structure. The stress-strain chart of the PA and CF/PA rectilinear pattern reveals a similar behavior, and there are no significant variances among the results of 70, 85, and 100% infill percentages.\u003c/p\u003e \u003cp\u003eThe IPFs of all triangle pattern samples are more significantly affected by the sample wall thickness than the infill percentage. Since outer rigidity is absent in the small wall thickness samples, the IPF was found to be much smaller than those with thicker outer walls. A sample of only 85% infill and with the highest wall thickness (6 mm) possesses a larger IPF (27.39 KN) than that of a sample with 100% infill and 6 mm wall thickness (27.21 KN). In contrast, samples with 1.2 mm wall thickness and 70, 85 and 100% infill have the lowest IPFs of 19.10, 21.51 and 21.95 KN, respectively. Similarly, for EA, the sample with only 85% infill and 6 mm wall thickness has the highest EA (3657.03 J) for PA. The infill percentage only has a minimal effect on energy absorption. So, the lowest EA, 2156.74 J, is observed in the sample with the thinnest wall of 1.2 mm and the highest infill percentage of 100%. The SEA of the triangle pattern drops around 70% with the amalgamation of CF in PA. It is also demonstrated that PA specimens have higher SEAs than their CF/PA counterparts. When the wall thickness is set to 6 mm, the infill percentage influences the CFE of the 3D-printed triangle pattern PA little. When the infill percentage is 70%, 85% or 100%, the triangle pattern with a wall thickness of 1.2 mm has a smaller CFE than that with a 3.6 mm wall thickness.\u003c/p\u003e \u003cp\u003eThe triangle pattern is stronger than the rectilinear pattern due to the separation of the internal structure of the rectilinear pattern and the easy occurrence of sliding for a small wall thickness rectilinear sample. The sample of 85% infill and 6 mm wall thickness has the highest IPF (27.39 and 28 KN) and EA (3657.03 and 3800 J) for PA12 triangle and rectilinear patterns, respectively. The rectilinear pattern sample of 70% infill and 1.2 mm outer wall thickness has almost the lowest IPF (13 and 1875 KN) and EA (1252 and 196 J) for PA12 and CF/PA samples, respectively. The PA sample of 85% infill, 6 mm wall thickness and a rectilinear pattern has a superior SEA compared to all other triangle and rectilinear samples. The highest value of CFE for all triangle and rectilinear samples was observed in the sample of 70% infill and 6 mm wall thickness.\u003c/p\u003e \u003cp\u003eThe impact strength of the triangle CF/PA sample of 1.2 mm wall thickness and 70% infill was 2.46 kJ/m\u003csup\u003e2\u003c/sup\u003e, while the strength of the 6 mm wall thickness and 100% infill specimen was the highest of all PA and PA/CF specimens, reaching 9.22 kJ/m\u003csup\u003e2\u003c/sup\u003e. The impact strength increased considerably for the rectilinear pattern PA/CF specimens. For the specimen with 100% infill and 1.2 mm wall thickness, the impact strength was 7.868937049 kJ/m\u003csup\u003e2\u003c/sup\u003e, while the strength of the specimen with 70% infill and 6 mm wall thickness was the highest of all rectilinear pattern PA 12 and PA/CF specimens, reaching 9.191810484 kJ/m\u003csup\u003e2\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study did not involve any human or animal subjects, data or tissue. Therefore, no ethical approval was required. The study followed the guidelines and standards of the International Organization for Standardization (ISO) and the American Society for Testing and Materials (ASTM) for 3D printing and testing of Nylon and CF/Nylon samples.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests of a financial or personal nature that could have influenced the design, execution or interpretation of this study. The authors have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed equally to this work. All authors conceived and designed the study. Mina and Khaled performed the 3D printing and testing of the samples. Mina and Sameh analyzed and interpreted the data. Sameh, Khaled and Tamer drafted and revised the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eIn this work, we are pursuing support by the Science and Technology Development Fund (STDF). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.\u003c/p\u003e\n\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eD\u0026apos;Urso PS, Redmond MJ: \u003cstrong\u003eA method for the resection of cranial tumours and skull reconstruction\u003c/strong\u003e. \u003cem\u003eBr J Neurosurg \u003c/em\u003e2000, \u003cstrong\u003e14\u003c/strong\u003e(6):555-559.\u003c/li\u003e\n\u003cli\u003eLohfeld S, Barron V, McHugh PE: \u003cstrong\u003eBiomodels of bone: a review\u003c/strong\u003e. \u003cem\u003eAnn Biomed Eng \u003c/em\u003e2005, \u003cstrong\u003e33\u003c/strong\u003e(10):1295-1311.\u003c/li\u003e\n\u003cli\u003eSood AK, Equbal A, Toppo V, Ohdar RK, Mahapatra SS: \u003cstrong\u003eAn investigation on sliding wear of FDM built parts\u003c/strong\u003e. \u003cem\u003eCIRP Journal of Manufacturing Science and Technology \u003c/em\u003e2012, \u003cstrong\u003e5\u003c/strong\u003e(1):48-54.\u003c/li\u003e\n\u003cli\u003eMatsuzaki R, Ueda M, Namiki M, Jeong TK, Asahara H, Horiguchi K, Nakamura T, Todoroki A, Hirano Y: \u003cstrong\u003eThree-dimensional printing of continuous-fiber composites by in-nozzle impregnation\u003c/strong\u003e. \u003cem\u003eSci Rep \u003c/em\u003e2016, \u003cstrong\u003e6\u003c/strong\u003e:23058.\u003c/li\u003e\n\u003cli\u003eCaulfield B, McHugh PE, Lohfeld S: \u003cstrong\u003eDependence of mechanical properties of polyamide components on build parameters in the SLS process\u003c/strong\u003e. \u003cem\u003eJournal of Materials Processing Technology \u003c/em\u003e2007, \u003cstrong\u003e182\u003c/strong\u003e(1-3):477-488.\u003c/li\u003e\n\u003cli\u003eRajpurohit SR, Dave HK: \u003cstrong\u003eEffect of process parameters on tensile strength of FDM printed PLA part\u003c/strong\u003e. \u003cem\u003eRapid Prototyping Journal \u003c/em\u003e2018, \u003cstrong\u003e24\u003c/strong\u003e(8):1317-1324.\u003c/li\u003e\n\u003cli\u003eZhang X, Chen L, Mulholland T, Osswald TA: \u003cstrong\u003eEffects of raster angle on the mechanical properties of PLA and Al/PLA composite part produced by fused deposition modeling\u003c/strong\u003e. \u003cem\u003ePolymers for Advanced Technologies \u003c/em\u003e2019, \u003cstrong\u003e30\u003c/strong\u003e(8):2122-2135.\u003c/li\u003e\n\u003cli\u003eNagendra J, Prasad MSG: \u003cstrong\u003eFDM Process Parameter Optimization by Taguchi Technique for Augmenting the Mechanical Properties of Nylon\u0026ndash;Aramid Composite Used as Filament Material\u003c/strong\u003e. \u003cem\u003eJournal of The Institution of Engineers (India): Series C \u003c/em\u003e2019, \u003cstrong\u003e101\u003c/strong\u003e(2):313-322.\u003c/li\u003e\n\u003cli\u003eWilliams CB, Cochran JK, Rosen DW: \u003cstrong\u003eAdditive manufacturing of metallic cellular materials via three-dimensional printing\u003c/strong\u003e. \u003cem\u003eThe International Journal of Advanced Manufacturing Technology \u003c/em\u003e2010, \u003cstrong\u003e53\u003c/strong\u003e(1-4):231-239.\u003c/li\u003e\n\u003cli\u003eJones R, Haufe P, Sells E, Iravani P, Olliver V, Palmer C, Bowyer A: \u003cstrong\u003eRepRap \u0026ndash; the replicating rapid prototyper\u003c/strong\u003e. \u003cem\u003eRobotica \u003c/em\u003e2011, \u003cstrong\u003e29\u003c/strong\u003e(1):177-191.\u003c/li\u003e\n\u003cli\u003eFernandez-Vicente M, Calle W, Ferrandiz S, Conejero A: \u003cstrong\u003eEffect of Infill Parameters on Tensile Mechanical Behavior in Desktop 3D Printing\u003c/strong\u003e. \u003cem\u003e3D Printing and Additive Manufacturing \u003c/em\u003e2016, \u003cstrong\u003e3\u003c/strong\u003e(3):183-192.\u003c/li\u003e\n\u003cli\u003eCooper K: \u003cstrong\u003eRapid prototyping technology: selection and application\u003c/strong\u003e: CRC press; 2001.\u003c/li\u003e\n\u003cli\u003ePereira TF, Silva MAC, Oliveira MF, Maia IA, Silva JVL, Costa MF, Thir\u0026eacute; RMSM: \u003cstrong\u003eEffect of process parameters on the properties of selective laser sintered Poly(3-hydroxybutyrate) scaffolds for bone tissue engineering\u003c/strong\u003e. \u003cem\u003eVirtual and Physical Prototyping \u003c/em\u003e2012, \u003cstrong\u003e7\u003c/strong\u003e(4):275-285.\u003c/li\u003e\n\u003cli\u003eTan K, Chua C, Leong K, Cheah C, Cheang P, Bakar MA, Cha SJB: \u003cstrong\u003eScaffold development using selective laser sintering of polyetheretherketone\u0026ndash;hydroxyapatite biocomposite blends\u003c/strong\u003e. 2003, \u003cstrong\u003e24\u003c/strong\u003e(18):3115-3123.\u003c/li\u003e\n\u003cli\u003eHo HCH, Cheung WL, Gibson IJI, research ec: \u003cstrong\u003eMorphology and properties of selective laser sintered bisphenol a polycarbonate\u003c/strong\u003e. 2003, \u003cstrong\u003e42\u003c/strong\u003e(9):1850-1862.\u003c/li\u003e\n\u003cli\u003eSalazar A, Rico A, Rodr\u0026iacute;guez J, Segurado Escudero J, Seltzer R, Martin de la Escalera Cutillas F: \u003cstrong\u003eFatigue crack growth of SLS polyamide 12: Effect of reinforcement and temperature\u003c/strong\u003e. \u003cem\u003eComposites Part B: Engineering \u003c/em\u003e2014, \u003cstrong\u003e59\u003c/strong\u003e:285-292.\u003c/li\u003e\n\u003cli\u003eVan Hooreweder B, De Coninck F, Moens D, Boonen R, Sas P: \u003cstrong\u003eMicrostructural characterization of SLS-PA12 specimens under dynamic tension/compression excitation\u003c/strong\u003e. \u003cem\u003ePolymer Testing \u003c/em\u003e2010, \u003cstrong\u003e29\u003c/strong\u003e(3):319-326.\u003c/li\u003e\n\u003cli\u003eMishra PK, Senthil P, Adarsh S, Anoop MS: \u003cstrong\u003eAn investigation to study the combined effect of different infill pattern and infill density on the impact strength of 3D printed polylactic acid parts\u003c/strong\u003e. \u003cem\u003eComposites Communications \u003c/em\u003e2021, \u003cstrong\u003e24\u003c/strong\u003e.\u003c/li\u003e\n\u003cli\u003eSingh R, Kumar R, Singh M, Preet P: \u003cstrong\u003eOn compressive and morphological features of 3D printed almond skin powder reinforced PLA matrix\u003c/strong\u003e. \u003cem\u003eMaterials Research Express \u003c/em\u003e2020, \u003cstrong\u003e7\u003c/strong\u003e(2).\u003c/li\u003e\n\u003cli\u003eWu D, Spanou A, Diez-Escudero A, Persson C: \u003cstrong\u003e3D-printed PLA/HA composite structures as synthetic trabecular bone: A feasibility study using fused deposition modeling\u003c/strong\u003e. \u003cem\u003eJ Mech Behav Biomed Mater \u003c/em\u003e2020, \u003cstrong\u003e103\u003c/strong\u003e:103608.\u003c/li\u003e\n\u003cli\u003eLiu K, Li W, Chen S, Wen W, Lu L, Liu M, Zhou C, Luo B: \u003cstrong\u003eThe design, fabrication and evaluation of 3D printed gHNTs/gMgO whiskers/PLLA composite scaffold with honeycomb microstructure for bone tissue engineering\u003c/strong\u003e. \u003cem\u003eComposites Part B: Engineering \u003c/em\u003e2020, \u003cstrong\u003e192\u003c/strong\u003e.\u003c/li\u003e\n\u003cli\u003eQin D, Sang L, Zhang Z, Lai S, Zhao Y: \u003cstrong\u003eCompression Performance and Deformation Behavior of 3D-Printed PLA-Based Lattice Structures\u003c/strong\u003e. \u003cem\u003ePolymers (Basel) \u003c/em\u003e2022, \u003cstrong\u003e14\u003c/strong\u003e(5).\u003c/li\u003e\n\u003cli\u003eZagidullin RS, Zezin NI, Rodionov NV: \u003cstrong\u003eImproving the quality of FDM 3D printing of UAV and aircraft parts and assemblies by parametric software changes\u003c/strong\u003e. \u003cem\u003eIOP Conference Series: Materials Science and Engineering \u003c/em\u003e2021, \u003cstrong\u003e1027\u003c/strong\u003e(1).\u003c/li\u003e\n\u003cli\u003ePrayitno G, Imaduddin F, Ubaidillah, Arifin Z: \u003cstrong\u003eRecent Progress of Fused Deposition Modeling (FDM) 3D Printing: Constructions, Parameters and Processings\u003c/strong\u003e. \u003cem\u003eIOP Conference Series: Materials Science and Engineering \u003c/em\u003e2021, \u003cstrong\u003e1096\u003c/strong\u003e(1).\u003c/li\u003e\n\u003cli\u003eGaleja M, Hejna A, Kosmela P, Kulawik A: \u003cstrong\u003eStatic and Dynamic Mechanical Properties of 3D Printed ABS as a Function of Raster Angle\u003c/strong\u003e. \u003cem\u003eMaterials (Basel) \u003c/em\u003e2020, \u003cstrong\u003e13\u003c/strong\u003e(2).\u003c/li\u003e\n\u003cli\u003ePollard D, Ward C, Herrmann G, Etches J: \u003cstrong\u003eThe manufacture of honeycomb cores using Fused Deposition Modeling\u003c/strong\u003e. \u003cem\u003eAdvanced Manufacturing: Polymer \u0026amp; Composites Science \u003c/em\u003e2017, \u003cstrong\u003e3\u003c/strong\u003e(1):21-31.\u003c/li\u003e\n\u003cli\u003eAlam F, Shukla VR, Varadarajan KM, Kumar S: \u003cstrong\u003eMicroarchitected 3D printed polylactic acid (PLA) nanocomposite scaffolds for biomedical applications\u003c/strong\u003e. \u003cem\u003eJ Mech Behav Biomed Mater \u003c/em\u003e2020, \u003cstrong\u003e103\u003c/strong\u003e:103576.\u003c/li\u003e\n\u003cli\u003eLiu H, He H, Peng X, Huang B, Li J: \u003cstrong\u003eThree-dimensional printing of poly(lactic acid) bio-based composites with sugarcane bagasse fiber: Effect of printing orientation on tensile performance\u003c/strong\u003e. \u003cem\u003ePolymers for Advanced Technologies \u003c/em\u003e2019, \u003cstrong\u003e30\u003c/strong\u003e(4):910-922.\u003c/li\u003e\n\u003cli\u003eGajdo\u0026scaron; I, Slota JJTv: \u003cstrong\u003eInfluence of printing conditions on structure in FDM prototypes\u003c/strong\u003e. 2013, \u003cstrong\u003e20\u003c/strong\u003e(2):231-236.\u003c/li\u003e\n\u003cli\u003eNgo TD, Kashani A, Imbalzano G, Nguyen KTQ, Hui D: \u003cstrong\u003eAdditive manufacturing (3D printing): A review of materials, methods, applications and challenges\u003c/strong\u003e. \u003cem\u003eComposites Part B: Engineering \u003c/em\u003e2018, \u003cstrong\u003e143\u003c/strong\u003e:172-196.\u003c/li\u003e\n\u003cli\u003ePapa I, Silvestri AT, Ricciardi MR, Lopresto V, Squillace A: \u003cstrong\u003eEffect of Fibre Orientation on Novel Continuous 3D-Printed Fibre-Reinforced Composites\u003c/strong\u003e. \u003cem\u003ePolymers (Basel) \u003c/em\u003e2021, \u003cstrong\u003e13\u003c/strong\u003e(15).\u003c/li\u003e\n\u003cli\u003eVan Hooreweder B, Moens D, Boonen R, Kruth J-P, Sas P: \u003cstrong\u003eOn the difference in material structure and fatigue properties of nylon specimens produced by injection molding and selective laser sintering\u003c/strong\u003e. \u003cem\u003ePolymer Testing \u003c/em\u003e2013, \u003cstrong\u003e32\u003c/strong\u003e(5):972-981.\u003c/li\u003e\n\u003cli\u003eMonzon MD, Paz R, Ortega F, Chapela JA, Conde C: \u003cstrong\u003eProcess for reinforcing SLS parts by epoxy resin\u003c/strong\u003e. \u003cem\u003eRapid Prototyping Journal \u003c/em\u003e2015, \u003cstrong\u003e21\u003c/strong\u003e(3):322-328.\u003c/li\u003e\n\u003cli\u003eTang C, Liu J, Yang Y, Liu Y, Jiang S, Hao W: \u003cstrong\u003eEffect of process parameters on mechanical properties of 3D printed PLA lattice structures\u003c/strong\u003e. \u003cem\u003eComposites Part C: Open Access \u003c/em\u003e2020, \u003cstrong\u003e3\u003c/strong\u003e.\u003c/li\u003e\n\u003cli\u003eSaenz F, Otarola C, Valladares K, Rojas J: \u003cstrong\u003eInfluence of 3D printing settings on mechanical properties of ABS at room temperature and 77 K\u003c/strong\u003e. \u003cem\u003eAdditive Manufacturing \u003c/em\u003e2021, \u003cstrong\u003e39\u003c/strong\u003e.\u003c/li\u003e\n\u003cli\u003eBartolom\u0026eacute; E, Bozzo B, Sevilla P, Mart\u0026iacute;nez-Pasarell O, Puig T, Granados X: \u003cstrong\u003eABS 3D printed solutions for cryogenic applications\u003c/strong\u003e. \u003cem\u003eCryogenics \u003c/em\u003e2017, \u003cstrong\u003e82\u003c/strong\u003e:30-37.\u003c/li\u003e\n\u003cli\u003eTymrak BM, Kreiger M, Pearce JM: \u003cstrong\u003eMechanical properties of components fabricated with open-source 3-D printers under realistic environmental conditions\u003c/strong\u003e. \u003cem\u003eMaterials \u0026amp; Design \u003c/em\u003e2014, \u003cstrong\u003e58\u003c/strong\u003e:242-246.\u003c/li\u003e\n\u003cli\u003eJohnson GA, French JJJAiTI: \u003cstrong\u003eEvaluation of infill effect on mechanical properties of consumer 3D printing materials\u003c/strong\u003e. 2018, \u003cstrong\u003e3\u003c/strong\u003e(4):179.\u003c/li\u003e\n\u003cli\u003eSuteja TJ, Soesanti A: \u003cstrong\u003eMechanical Properties of 3D Printed Polylactic Acid Product for Various Infill Design Parameters: A Review\u003c/strong\u003e. \u003cem\u003eJournal of Physics: Conference Series \u003c/em\u003e2020, \u003cstrong\u003e1569\u003c/strong\u003e(4).\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003ePolyamide (PA12) for Industrial 3D Printing: EOS GmbH \u003c/strong\u003e[https://www.eos.info/en/additive-manufacturing/3d-printing-plastic/sls-polymer-materials/polyamide-pa-12-alumide\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eePA12-CF \u003c/strong\u003e[https://www.esun3d.com/epa12-cf-product/]\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eSLS Printer FORMIGA P 110 Velocis \u003c/strong\u003e[https://www.eos.info/en/additive-manufacturing/3d-printing-plastic/eos-polymer-systems/formiga-p-110-velocis]\u003c/li\u003e\n\u003cli\u003eKananathan J, Samykano M, Kadirgama K, Ramasamy D, Rahman MM: \u003cstrong\u003eComprehensive investigation and prediction model for mechanical properties of coconut wood\u0026ndash;polylactic acid composites filaments for FDM 3D printing\u003c/strong\u003e. \u003cem\u003eEuropean Journal of Wood and Wood Products \u003c/em\u003e2021, \u003cstrong\u003e80\u003c/strong\u003e(1):75-100.\u003c/li\u003e\n\u003cli\u003eLi S, Song Y, Song Y, Shi J, Liu L, Wei X, Guo QJC: \u003cstrong\u003eCarbon foams with high compressive strength derived from mixtures of mesocarbon microbeads and mesophase pitch\u003c/strong\u003e. 2007, \u003cstrong\u003e45\u003c/strong\u003e(10):2092-2097.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eEnder-3 Software\u0026amp; Firmware Download - Creality 3D Printer \u003c/strong\u003e[https://www.creality.com/pages/download-ender-3?spm=..product_ce00868d-efe2-4fa8-9168-240e7c3b3cd1.nav_link_store_1.1]\u003c/li\u003e\n\u003cli\u003eMaran JP, Manikandan SJD, Pigments: \u003cstrong\u003eResponse surface modeling and optimization of process parameters for aqueous extraction of pigments from prickly pear (Opuntia ficus-indica) fruit\u003c/strong\u003e. 2012, \u003cstrong\u003e95\u003c/strong\u003e(3):465-472.\u003c/li\u003e\n\u003cli\u003eDanbaba N, Nkama I, Badau MHJIJoFS, Engineering N: \u003cstrong\u003eApplication of response surface methodology (RSM) and central composite design (CCD) to optimize minerals composition of rice-cowpea composite blends during extrusion cooking\u003c/strong\u003e. 2015, \u003cstrong\u003e5\u003c/strong\u003e(1):40-52.\u003c/li\u003e\n\u003cli\u003eAyutsede J, Gandhi M, Sukigara S, Ye H, Hsu C-m, Gogotsi Y, Ko FJB: \u003cstrong\u003eCarbon nanotube reinforced Bombyx mori silk nanofibers by the electrospinning process\u003c/strong\u003e. 2006, \u003cstrong\u003e7\u003c/strong\u003e(1):208-214.\u003c/li\u003e\n\u003cli\u003eXie Y, Chen J, Zhao H, Huang F: \u003cstrong\u003ePrediction of the fiber diameter of melt electrospinning writing by kriging model\u003c/strong\u003e. \u003cem\u003eJournal of Applied Polymer Science \u003c/em\u003e2022, \u003cstrong\u003e139\u003c/strong\u003e(21).\u003c/li\u003e\n\u003cli\u003eInternational A: \u003cstrong\u003eStandard test method for compressive properties of rigid plastics\u003c/strong\u003e: ASTM International; 2010.\u003c/li\u003e\n\u003cli\u003eZhang L, Feih S, Daynes S, Chang S, Wang MY, Wei J, Lu WFJAM: \u003cstrong\u003eEnergy absorption characteristics of metallic triply periodic minimal surface sheet structures under compressive loading\u003c/strong\u003e. 2018, \u003cstrong\u003e23\u003c/strong\u003e:505-515.\u003c/li\u003e\n\u003cli\u003eTesting AASf, Materials: \u003cstrong\u003eASTM D6110-18: standard test method for determining the charpy impact resistance of notched specimens of plastics\u003c/strong\u003e. In\u003cem\u003e.\u003c/em\u003e: ASTM International West Conshohocken; 2018.\u003c/li\u003e\n\u003cli\u003eWang X-T, Wang B, Li X-W, Ma LJIJoMS: \u003cstrong\u003eMechanical properties of 3D re-entrant auxetic cellular structures\u003c/strong\u003e. 2017, \u003cstrong\u003e131\u003c/strong\u003e:396-407.\u003c/li\u003e\n\u003cli\u003eHull DJCs, technology: \u003cstrong\u003eA unified approach to progressive crushing of fibre-reinforced composite tubes\u003c/strong\u003e. 1991, \u003cstrong\u003e40\u003c/strong\u003e(4):377-421.\u003c/li\u003e\n\u003cli\u003eZhang Y, Zong Z, Liu Q, Ma J, Wu Y, Li QJM, Design: \u003cstrong\u003eStatic and dynamic crushing responses of CFRP sandwich panels filled with different reinforced materials\u003c/strong\u003e. 2017, \u003cstrong\u003e117\u003c/strong\u003e:396-408.\u003c/li\u003e\n\u003cli\u003eLiu X, Wada T, Suzuki A, Takata N, Kobashi M, Kato MJM, Design: \u003cstrong\u003eUnderstanding and suppressing shear band formation in strut-based lattice structures manufactured by laser powder bed fusion\u003c/strong\u003e. 2021, \u003cstrong\u003e199\u003c/strong\u003e:109416.\u003c/li\u003e\n\u003cli\u003eArao Y, Taniguchi N, Nishiwaki T, Hirayama N, Kawada HJJoMS: \u003cstrong\u003eStrain-rate dependence of the tensile strength of glass fibers\u003c/strong\u003e. 2012, \u003cstrong\u003e47\u003c/strong\u003e(12):4895-4903.\u003c/li\u003e\n\u003cli\u003eKumar S, Ubaid J, Abishera R, Schiffer A, Deshpande VJAam, interfaces: \u003cstrong\u003eTunable energy absorption characteristics of architected honeycombs enabled via additive manufacturing\u003c/strong\u003e. 2019, \u003cstrong\u003e11\u003c/strong\u003e(45):42549-42560.\u003c/li\u003e\n\u003cli\u003eAndrew JJ, Verma P, Kumar SJM, Design: \u003cstrong\u003eImpact behavior of nanoengineered, 3D printed plate-lattices\u003c/strong\u003e. 2021, \u003cstrong\u003e202\u003c/strong\u003e:109516.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Selective laser sintering, Fused deposition modeling, Polyamide powder, Short Carbon fiber, Compression, Impact","lastPublishedDoi":"10.21203/rs.3.rs-2948690/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2948690/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"3D printing techniques are becoming more common within several industrial fields due to their many benefits. These benefits include customized properties of final products, design independence, demand-driven manufacturing, waste alleviation, and the ability to produce complex parts, as well as fast prototyping. Parts manufactured using the powder bed fusion or material extrusion process are achievable by various building parameters. In this investigation, a comprehensive study was undertaken to clarify the variation in the compressive and impact strength of SLS prepared Nylon Polyamide and FDM prepared Nylon/CF parts at different building parameters. Significant methodological parameters were studied: infill patterns/layer layouts (triangular and rectilinear), wall thickness (1.2, 3.6, 6) and infilled density (70, 85 and 100%), utilizing material extrusion and powder bed fusion 3D printing machines. The Central Composite Face-centered (CCF)method was applied to design an optimal number of experiments. Experimental results demonstrated that Nylon Polyamide and Nylon/CF samples present slightly different crashing patterns and mechanical behaviors when tested for compression and impact. Compression characteristics of all tested samples are a progressive folding and lateral shearing failures amalgamation. Rectilinear samples are mechanically weaker than Triangle samples.","manuscriptTitle":"The effect of printing parameters on crushing behavior of 3D printed Nylon and CF/Nylon samples using Powder Bed Fusion and Material Extrusion techniques","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-06-05 14:48:49","doi":"10.21203/rs.3.rs-2948690/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2023-06-03T07:51:25+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2023-06-01T19:13:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2023-05-30T03:18:03+00:00","index":"","fulltext":""},{"type":"submitted","content":"The International Journal of Advanced Manufacturing Technology","date":"2023-05-29T17:41:14+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"cc82cde2-f14c-44ae-a2f5-e6c39431a159","owner":[],"postedDate":"June 5th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2023-06-05T14:48:50+00:00","versionOfRecord":[],"versionCreatedAt":"2023-06-05 14:48:49","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2948690","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2948690","identity":"rs-2948690","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}