Mechanical and Dynamic Behavior of Banana/cork Sandwich Structures: An Integrated Experimental and Finite Element Study

Mechanical and Dynamic Behavior of Banana/cork Sandwich Structures: An Integrated Experimental and Finite Element Study | 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 Mechanical and Dynamic Behavior of Banana/cork Sandwich Structures: An Integrated Experimental and Finite Element Study Hammad Ali This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8935058/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The need related to the continuous rise of sustainable structural materials with superior vibration attenuation has intensified the study of bio-based sandwich materials in recent times. To conduct this research, a hybrid sandwich composite was fabricated using woven banana fabric face sheets and cork agglomerate cores via using vacuum bagging methodology and systematically tested on its mechanical, dynamic and impact performance characteristics. Experimentally, tensile, free-decay vibration, modal vibration, Charpy and Izod impact tests were used to test the behavior of monolithic banana fabric laminates and sandwich configurations with different core cork thicknesses. Finite Element (FE) models were prepared in Abaqus to reproduce the global mechanical and dynamic response and has been compared with practical experimentation. The findings indicate that although the addition of cork cores causes the tensile strength to reduce in a controlled fashion, it has a considerable effect in complementing the vibration and absorption of impact energy. It was found that damping ratios had increased over 200% with increased cork core thickness and that natural frequency had decreased roughly 25-40% which signifies that the damping capability of the sample improved in terms of vibration isolation. Energy absorption due to impact was enhanced up to 40% of L2, L3. Materials Engineering Bio-composites Sandwich structures Cork agglomerate Banana fiber Vibration damping Modal analysis Vacuum bagging Sustainable materials Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 INTRODUCTION Sustainable engineering solutions, necessitated by the need to minimize environmental impact coupled with preservation or improvement of structural performance, has become a major paradigm in materials science. In this respect, natural fiber-reinforced polymer (NFRP) composites have become potential alternatives to their synthetic analogs in different structural and semi-structural applications. Nevertheless, dynamic performance, especially vibration damping and impact resistance which are needed in components that have to work in the dynamic loading environment is usually a constraint to the widespread use of monolithic NFRP. A good principle to counter these constraints is the sandwich construction principle, where the stiff and strong face sheets are mixed to form an energy absorbing, and lightweight core. In this paper, we examine how to develop and characterize a completely bio-based hybrid sandwich composite, which is innovatively made of woven banana fabric face sheets and cork agglomerate cores. Systematic study of this sustainable material system mechanical, dynamic, and impact performances is conducted, and the results are verified with the help of a finite element (FE) model. Background and Motivation The fact that sustainability and environmental responsibility is continually gaining momentum has led to heightened interest in replacing synthetic fiber-reinforced polymer composites with natural fiber-reinforced polymers (NFRP) in structural and semi-structural product use. It has been endorsed in literature that NFRPs also have certain benefits that include the low density, renewability, low environmental impact, and competitive specific mechanical properties [ 1 – 4 ]. Banana fiber is one of the natural fibers which have attracted interest because of their broad availability, good tensile indicators and can be used in woven and textile-based reinforcement architecture [ 5 – 8 ]. Although banana fiber fabric has these benefits, monolithic natural fiber composites can be regularly constrained by rather low vibration damping and impact resistance that curtail their applications in vibration-sensitive and dynamic loading conditions [ 9 – 11 ]. Some common biobased material candidates with their key mechanical properties and performance characteristics. In order to address these shortcomings, sandwich composite designs in which lightweight and energy-absorbing cores are used are widely studied [ 12 – 14 ]. In these types of structures, the overall in-plane loads are supported by rigid face sheets with compliant cores assisting in dissipating energy as well as the dampening of vibrations and resistance to impact [ 15 ]. 1.2 Related Work and Research Gap Cork agglomerate has also proved a highly interesting bio-based core material as it possesses a closed-cell structure, the viscoelastic behavior, low density, and good energy absorption property [ 16 – 19 ]. A few studies have established that cork cores offer considerable benefits in vibration damping, impact and sounding when used in sandwich structures especially with synthetic face sheets [ 20 – 22 ]. Simultaneously, it has been noted that sandwich composites with a polymeric or foam core combined with natural fiber face sheets represent a promising alternative [ 24 – 26 ] to lightweight and sustainable material classes. One of the most popular methods to forecast the mechanical and dynamic behavior of sandwich composites is finite element (FE) modeling, which has been applied to justify experimental studies [ 27 – 29 ]. However, the FE methods have not reached the natural fiber-cork hybrid systems because of the heterogeneity of materials, the variability of the interfaces, and the lack of certainty concerning effective material properties already observed in the past literature [ 30 , 31 ]. The research work is aimed at examining the mechanical, dynamic and impact performance of a hybrid sandwich composite made of woven banana sheets, and cores of cork agglomerate of different thicknesses under the vacuum bagging process. Tensile testing through experiments, free-decay vibration testing, modal testing and Charpy and Izod impact tests are done to measure the impact of cork core thickness on structural behavior. The main contributions of the work are three-fold: Production of a bio-based cork sandwich banana fabric-cork sandwich composite entirely manufactured using an industry-relevant vacuum bagging process; A thorough experimental investigation of tensile, dynamic and impact behavior with specific focus to vibration damping performance; and Confirmation of a model framework of a finite element framework that has the capacity to forecast global mechanical and modal response. The results of the research present design-applicable information on the sustainable sandwich composites and creates a basis on the application of the research in the vibration-sensitive and sustainability-driven engineering systems. To meet these goals, a complete bio-based hybrid sandwich composite was created where the face sheets were composed of woven banana fabric and the core constituted of cork agglomerate sheets (3 mm and 6 mm thick) where the epoxy matrix bonded everything using the vacuum bagging method as posited in Fig. 4 . Tensile testing (ASTM D3039), free-decay vibration analysis, modal vibration testing and Charpy and Izod impact tests were used as experimental investigation to assess the mechanical, dynamic and impact performance. Also to simulate the overall mechanical and dynamic responses, Finite Element (FE) models have been created in Abaqus, which offer a justifiable numerical model as a basis of predictive design. It is a combined experimental-numerical method that not only confirms the feasibility of the proposed sustainable composite system but also provides practical facts of applying them to the vibration-sensitive and semi-structural fields. It is a reliable experimental-numerical study that provides a proven guide to the design and implementation of sustainable sandwich composites in the vibration-sensitive jobs [ 32 ], [ 33 ]. The findings affirm the viability of banana fabric-cork hybrid systems and prove the possibility of reproducing the manufacturing and modeling protocol of the future development of bio-based composites [ 34 ], [ 35 ]. The subsequent chapters provide the materials, methodology of the experiment, and results, which support these contributions. MATERIALS AND METHODS This paper incorporated both experimental research and numerical assessment to develop and investigate a novel fully bio-based sandwich composite. The plan included: (i) identification and definition of sustainable materials (ii) an elaborated and optimized vacuum-bagging fabrication (iii) the manufacturing of three different composite configurations to compare them (iv) a complete set of mechanical, dynamic, and impact tests (v) checking and validating finite-elements to forecast the behavior of the material. Such a methodical practice was supposed to provide the guarantee of reproducibility, to give solid performance statistics, and to present a predictive design tool of such a type of sustainable materials [ 36 ]. 2.1. Materials and Specifications The material system is a fully bio-based system composed of hybrid sandwich composite that was developed and delivers the functional requirements of semi-structural applications and goal sustainability. 2.1.1. Banana Fabric Face Sheets The primary reinforcement was plain-weave banana thread (Fig. 1 ) depicts the fabric. It is made of cotton warp, 100% banana-weft. This design provides a relative balance between drapeability and handling during lay-up. The fabric weighs 231.2 ± 0.2 g/m². According to supplier data that has been validated by previous research, fibers contain a healthy lot of cellulose, this provides them with tensile strength of 500–700 MPa and Young’s modulus of 12–20 GPa [ 37 – 39 ]. These important technical characteristics, including yarn count as well as tensile strength in warp and weft directions can be found in Table I. Table. I. Key Technical Properties of the Banana Fiber Fabrics (courtesy of PCSIR and The Natural Fibers Company.). Sr.# Parameters Method Used Units Results Uncertainty 1. Fiber Composition (warp/weft) ISO-1833-11 % Warp Yarn 100% Cotton Fiber Weft Yarn 100% Banana Fiber ± 0.000692% ± 0.00069 % 2. Tensile Strength (warp/weft) ISO-13934-1 N Warp = 121.46 Weft = 246.30 ± 43.28 N ± 18.66 N 3. Count of Yarn (Weft) ISO-7211-5 Ne 2.0 ± 0.15 Tex 4. Count of Yarn (Warp) ISO-7211-5 Ne 27.34 ± 0.15 Tex 5. Weight of Fabric (GSM) ISO-3801 g/m² 231.2 ± 0.216 g/m² Note: Testing Performed at Temperature of 20 ± 2°C and Relative Humidity of 65 ± 4% For the sustainable composite system, we selected this material over other bast fibers, i.e. flax or jute, because of its high specific strength and natural origin [ 40 ]. 2.1.2. Cork Agglomerate Core It was a core made of commercial cork agglomerate sheets (Fig. 2 .). These consist of cork granules that are expanded and bonded together using a polyurethane-based adhesive. We tested two nominal thicknesses L3 (3mm) and L2 (6mm). The density of all samples was stable at 200 ± 5 kg/m 3 . The above properties make it a perfect bio-based core in vibration attenuation [ 41 – 43 ]. The key core properties that are summarized in table iii, there is a compressive strength of approximately 1.35 MPa, and a deformation recovery that exceeds 90%. Table. II. Technical details of the cork agglomerate sheet (courtesy of Adenwalla Sons. Ltd.). Property Test method Result Block dimensions (manufacturing) Manufacturer spec 960 × 640 × 200 mm Density ASTM D 1752-18; ASTM D 545 − 23 200 kg·m⁻³ ± 5% Compression to 50% thickness ASTM D 1752-18; ASTM D 545 − 23 1.35 MPa (196 psi) Recovery after 50% compression ASTM D 1752-18; ASTM D 545 − 23 > 90% of original thickness Tensile strength ISO 7322 > 2000 kPa 2.1.3. Epoxy Matrix System Our matrix was a two-part low-viscosity epoxy, which is Ressichem Zepoxy. It was selected because it is compatible with natural fibers, cures at room temperature and has a viscosity range of 500–1000 CPs at 25°C. This type of viscosity enables the resin to impregnate the banana cloth and reach the core of the cork without excess resin [ 44 ]. The epoxy is cured with flexural strength of 56.6 MPa and compressive strength of 92.2 MPa, which is strong enough in the transfer of stress between the reinforcement and core after curing [ 45 ]. 2.2. Fabrication Process: Vacuum Bagging The high-quality, low-void laminate panels were manufactured with the help of a vacuum bagging process. Such a method had been selected over hand lay-up due to the superior pressure of the consolidation process and was also used to produce more consistent fiber volume fractions and interfacial bonding strength [ 46 ], [ 47 ]. 2.2.1. Layup Sequence and Preparation of the Mold. Banana Fabric- Cork Core -Banana Fabric. The mold used was made of a flat glass plate on which polyvinyl alcohol (PVA) release agent was spread. The pieces of banana fabrics were cut 310 x 310 mm and the cork core was cut 300 x 300 mm and had 5mm bleed for resin flow. Two layers of banana fabric were superimposed directly in the case of the monolithic control panel. 2.2.2. Vacuum Bagging and Curing Cycle The lay-up was put under a perforated release film, breather cloth, and a nylon vacuum bag. The vacuum pressure was maintained at 0.75 ± 0.05 bar, and held that way, both when infusing the resin, and in the first cure. The epoxy resin was also purged and pumped into the inlet trombone until all the fibers were saturated which was confirmed by the naked eye. Figure 3 . Summarizes the fabrication protocol which was created as a schedule to minimize voids, not to crush the core, and make certain that all the resin is polymerized without degrading the natural fibers [ 48 ],[ 49 ]. 2.3. Configuration and Test Matrix of Composites The effect of cork core and its thickness was separated by making three different laminate structures and testing them: Configuration L1 (Monolithic): Two layers of banana fabric/epoxy (Thickness is around 2.0mm), this was used as a baseline control. Configuration L2 (Sandwich- Thick Core) was Banana fabric / 6mm Core Cork / Banana fabric (àpprox ~ 8.2mm thick). Configuration L3 (Sandwich -Thin Core): Banana fabric / 3mm Cork Core / Banana fabric (about 5.1mm thick). Each configuration had five panels that were made. These panels yielded at least five specimens of the same kind, to assure statistical relevance, and to allow variation between natural materials [ 50 ]. 2.4. Mechanical, Dynamic testing methods Mechanical and dynamic performances of the fabricated hybrid composites were assessed by the way of a complete experimental campaign. To ensure that the behavior under useful conditions was captured, tests were done under quasi-static loading, dynamic loading, and impact loading. 2.4.1. Tensile Testing Quasi -static tensile tests were performed following ASTM D3039 [ 51 ] on a universal testing machine (Shimadzu AG-X Plus) with 30 kN load cell. A crosshead speed of 2mm/minute and rectangular coupons (250mm25x8.14mm) were tested. The ultimate tensile strength (UTS), Young modulus (E), and failure strain were measured. Figure 9 . shows universal testing machine with mounts and fixtures accommodated to perform mechanical tensile testing according to various ASTM, ISO, and many other standardized protocols under regulated conditions. 2.4.2. Impact Testing Charpy (unnotched) and Izod impact resistance tests were carried out to determine the toughness of the material and its ability to absorb energy at high-rate loading. A pendulum impact tester (Instron Ceast 9340) was tested. The impact specimens are shown in Fig. 4 . Charpy Impact: This test was carried out as per ISO 179-1 [ 52 ] on specimens (80 x 10 x 8.14 mm) as shown in. The calculated impact strength (kJm2) and impact energy (in Joules) were then measured. Izod Impact: Tests were performed as per ASTM D256 [ 53 ] on notched samples (63.5 x12.7 x 8.14 mm). 2.4.3. Dynamic Mechanical Analysis: In Free-Decay and Modal Testing, the properties of the vibration damper were tested by two conflicting methods. In Free -Decay Test, Cantilever beam specimens (200x20 mm) were held in place at one end and a lightweight accelerometer was applied as shown in Fig. 5 . Time-domain signal was used to compute the logarithmic decrement (δ) and the damping ratio (ζ) [ 54 ]. In Modal Analysis, an impulse hammer was used to excite the same specimens and the frequency response was recorded. The initial three natural frequencies (f 1 , f 2 , f 3 ) and mode shapes were determined by a modal analysis software package which gives an insight into global mass distribution and stiffness [ 55 ]. 2.5. Finite Element Framework Model Abaqus/CAE 2020 was developed into Finite Element (FE) models to model the experimental tests and forecast the mechanical and dynamic response of the composite. The usefulness of this computational framework is that it allows optimization of banana fabric-cork sandwich composites in the future to achieve specific engineering goals as a result of experimentation. The models that were developed had a twofold role to play, not only to offer information on the location of stress distribution, initiation point of failure, and dissipation of energy that cannot easily be experimentally obtained. Second, these developed a predictive tool, proven to be reliable, to investigate design parameters outside the tested design combinations, including different density of the core or face-sheet layups. 2.5.1. Model Geometry and Material Properties Three dimensional deformable parts were produced to fit in the exact size of the test specimens. The sandwich structure was modelled using a layered composite design, with plies of banana fabric being considered an orthotropic elastic material (E 1 , E 2 , v 12 , G 12 ) and the material properties were obtained based on Monolithic L1 test data. The cork core was modeled as an isotropic, crushable foam taking into consideration plasticity to represent its compressive energy absorptive nature. The effect of epoxy matrix and interfacial bonding was implicitly considered through the composite section definition and cohesive zone models that were used at face-sheet/core interface and cohesive zone respectively [ 56 ],[ 57 ]. The parametric setup details of simulation are detailed in table iii. Table. III. Material property inputs for Finite Element (FE) simulations in Abaqus. Material / Property Value Units Description / Source Banana Fabric/Epoxy Lamina (Orthotropic Elastic) Derived from monolithic (L1) test data • E₁ (Longitudinal Modulus) 8.4 ± 0.4 GPa In-plane, primary fiber direction • E₂ (Transverse Modulus) 3.1 ± 0.2 GPa In-plane, perpendicular to fibers • ν₁₂ (Poisson's Ratio) 0.33 – Literature • G₁₂ (Shear Modulus) 2.8 ± 0.3 GPa Estimated Cork Core (Crushable Foam Plasticity) Supplier data & literature [ 41 , 56 ] • Elastic Modulus, E 15 ± 2 MPa Initial linear elastic slope • Plastic Poisson's Ratio 0.0 – For volumetric crushing • Initial Yield Stress 1.35 MPa Start of plastic plateau Interface (Cohesive Surface) Calibrated from shear tests • Normal Strength 10.0 MPa Tensile debonding strength • Shear Strength 12.0 MPa Interfacial shear strength 2.5.2. Simulation of Tests Tensile Simulation A static general step with an imposed displacement boundary condition was made use of. The data on stress contours and force-displacement were obtained as depicted in Fig. 6 . In Modal Simulation, modal shapes and frequency, the modal shapes and frequencies were obtained through a linear perturbation step (Frequency), assuming that the material is linear under the condition of small amplitude vibrations. The kinetic, internal, and total energies were followed to ensure the stability of the simulation and calculate the absorbed energy [ 58 ]. Tensile modulus, natural frequencies and impact energy model predictions were directly compared with experimental values to verify the modeling framework; the differences were usually limited to some 10%. RESULTS & DISCUSSIONS In this chapter, the experimental and numerical findings on three composite constructions, namely monolithic banana fabric/epoxy (L1), and sandwich structures of the 6mm (L2) and 3mm (L3) cork cores, are provided and discussed. The data are arranged such that firstly, the baseline quasi-static tensile properties are determined and then dynamic vibration response, impact resistance, followed later by confirmation of the finite element (FE) models. 3.1. Tensile Properties and Failure Mechanisms Tensile behavior, summarized in Table VI demonstrates the anticipated tradeoff existent between strength and functional improvement. The ultimate tensile strength (UTS) of the monolithic L1 design was maximum at 54.4 ± 0.32 MPa and Youngs modulus 8.4 ± 0.4 GPa and was used as the benchmark in face-sheet performance. The stress-strain curve exhibited a linear elasticity and thereafter progressive failure which was manifested in form of pulling-out of the fibers and cracking of the matrix. When the cork core was added to it, the mechanical response changed remarkably. Configuration L2 (6 mm cork-core) had lost 43% of the UTS (31.2 ± 2.8 MPa) and 26% of the modulus (6.2 ± 0.3 GPa) to L1. This reduction is because the cork is less stiff and strong to support part of the tensile load, and has a greater likelihood of defects at the greater face-sheet/ core interface [ 59 ], [ 60 ]. The combined results of mechanical tensile tests are demonstrated in Fig. 7 . Configuration L3 (3 mm core-cork) was a good tradeoff. It still had 67% of monolithic UTS (36.3 ± 3.1 MPa) and 85% of the modulus (7.1 ± 0.3 GPa). The fact that this is an intermediate performance indicates that the thin core is sufficient in functional volume and reduces the adverse effects of a low-strength center portion as much as possible [ 61 – 64 ]. Upon density correction, results of the specific tensile strength of L3 equalized that of L1 as a demonstration of the weight-saving advantage of the sandwich design to applications where absolute strength can be exchanged with multifunctionality. The reduction of the tensile strength and modulus upon insertion of cork core is entirely in agreement with the classical sandwich theory which predicts that a low stiffness core will bear only a fraction of the in-plane load. The 43% decrease in ultimate tensile strength shown by the L2 (6mm) laminate is therefore not simply due to the inculpable weakness of cork. A thicker core enhances these mechanisms leading to early debonding at the interface or shearing of the core as shown by the finite - element simulations. In contrast, the L3 (3 mm) lamination shows that a thin compliant core is able to maintain an effective stress transfer between the face sheets with a relatively small penalty to the global strength. With that in view and regarding the specific strength (strength per unit of density) the L3 configuration may even exceed the monolithic laminate and thus emphasizes the weight-efficiency advantages of the sandwich layout for stiffness-driven, lightweight architectures. 3.2 Dynamic Response Mechanics The dynamic characterization is used to measure the main function of the cork agglomerate, which is vibration damping, and the measurements of free-decay and modal testing. The free Decay tests showed that there was a significant increase in the damping ratio when cork was introduced. For L1, the damping ratio was 0.012 ± 0.0002, L2 (ζ = 0.041), and L3 (ζ = 0.032) had an increase in this value by 267% and 167%, respectively. The plots of log-decays (Figure. 15.) show the fast attenuation of the amplitudes in the sandwich specimens as compared to the slow attenuating monolithic laminate [ 65 ]. This strengthening is also a direct consequence of the viscoelastic nature of cork in which the amount of energy lost to friction between cells inside the cork itself and at the resin/cork interface during the cyclical straining process. The natural frequency (f 1 ) fundamental reduced 42.30 Hz (L1) to 24.80 Hz (L2), and 31.60 Hz (L3). The decrease in the resonant frequency observed shows that the structure has become more compliant, which is beneficial toward non-resonant operational frequency redistribution, and hence vibration isolation [ 66 ], [ 67 ], [ 68 ]. High damping and lower natural frequency of the sandwich designs, especially in L2, assures their higher efficiency where the design is required to provide broadband vibration suppression as in equipment casing or automotive paneling. The significant improvement in the damping ratio up to a fantastic ratio of 267% with an increasing thickness of cork is directly related to the viscoelastic energy dissipation properties of the agglomerated cork cellular structure. We have measured the phenomenon in this study and have found that there is a strong positive relationship existing between core volume, or, correspondingly, core thickness, and damping capacity. Simultaneously, a reduction of 25 to 40% in the basic natural frequency represents the deliberate lowering of the global stiffness of the structure. This change has the advantage of vibration isolation, where this system replaces the resonant frequencies but the traditional conventional excitation frequencies noted in machinery or auto applications (usually in the 50–200 Hz range). 3.3 Impact Response Discussion One of the important factors that determine the damage tolerance, impact performance, showed a considerable improvement with the damage tolerance when combined with the sandwich configurations. Table VIII is a summary of Charpy and Izod impact strengths. The L1 sample (monolith) had an impact absorption of 4.2 ± 0.3 kJ/m 2 . The configurations of the sandwich L2 and L3 were found to have 131% and 98% higher absorption, and measured energies of 9.7 ± 0.3 kJ/m 2 and 8.3 ± 0.3 kJ/m 2 respectively [ 69 ]. Table. IV. Impact resistance of the composite configurations. Configuration Charpy Impact Strength (kJ/m²) Izod Impact Strength (kJ/m²) Impact Improvement vs. L1 (%) L1 (Monolithic) 4.2 ± 0.3 5.1 ± 0.1 – L2 (6 mm Cork Core) 9.7 ± 0.3 11.9 ± 0.2 + 131 (Charpy), + 133 (Izod) L3 (3 mm Cork Core) 8.3 ± 0.3 9.8 ± 0.2 + 98 (Charpy), + 92 (Izod) Similar trend was seen with Izod impact experiments. This changed the logic of fracturing into a brittle fracture in 1L to ductile, energy-absorbing in the sandwich specimens. Upon impact, the cork core experiences progressive cell collapse, which offers a significant amount of energy through plastic deformation before damage is transferred to the more brittle face sheets. Though L2 showed the highest absolute energy absorption, L3 showed a more balanced behavior of 98% improvement in Charpy impact resistance compared against L1, along with an equally superior tensile behavior than L2 [ 70 ]. These trends strengthen the inference that the core size of 3mm represents an effectively unchallenged trade-off in multifunctional design and that it also fulfils the impact resistance, damping and residual strength requirements. The impact energy absorption mechanism that gives the sandwich structures the high impact resistance is a sequential and multi-mode mechanism. The cork core, on colliding, is sacrificial crushing layer, and goes through a series of progressive plastic cell collapse. This long compaction period takes up a lot of energy before transmission of stress waves to the bottom face sheet, which prolongs catastrophic failure. Although the L2 (6mm) core captures the largest absolute energy, the L3 (3mm). It provides 98% of the maximum impact enhancement over the monolithic base and has 67% tensile strength. This gives L3 a special application to semi-structural applications, of the type of protective panel, interior component, or casing. 3.4 Finite Element Analysis Conclusions FE models were found to have good predictive ability of global mechanical and dynamic response, as Table V shows a comparison between experimental and simulated main measures. In the tensile properties the tensile ultimate strengths and tensile moduli, projected in all configurations, were found to be within the experimental averages within the range of + 10% to -10% [ 71 ], [ 72 ]. In the modal analysis, the natural frequencies of the first mode of the simulation were within a range of 12% error with respect to experiment and the mode shapes of the calculation were visually consistent with the experimentally determined ones. Table. V. Comparison of Experimental Results and Finite Element Model (FEA) Predictions Property / Configuration Experimental FEA Prediction Absolute Error Relative Error (%) Tensile UTS (MPa) • L1 (Monolithic) 54.4 ± 3.2 52.6 ± 1.8 -1.8 MPa -3.3 • L2 (6 mm Cork) 31.2 ± 2.8 37.1 ± 1.6 + 5.9 MPa + 18.9 • L3 (3 mm Cork) 36.3 ± 3.1 35.5 ± 1.5 -0.8 MPa -2.2 1st Natural Frequency, f₁ (Hz) • L1 (Monolithic) 42.3 ± 0.5 38.1 ± 0.4 -4.2 Hz -9.9 • L2 (6 mm Cork) 24.8 ± 0.3 22.3 ± 0.3 -2.5 Hz -10.1 • L3 (3 mm Cork) 31.6 ± 0.4 28.4 ± 0.3 -3.2 Hz -10.1 Charpy Impact Energy (J) • L1 (Monolithic) 0.33 ± 0.02 0.35 ± 0.01 + 0.02 J + 6.1 • L2 (6 mm Cork) 0.99 ± 0.03 1.05 ± 0.02 + 0.06 J + 6.1 • L3 (3 mm Cork) 0.59 ± 0.02 0.64 ± 0.02 + 0.05 J + 8.5 The internal development of the damage was visualized by the use of the validated model (Figure. 17.) and shows the spreading and constraint of stress waves in the cork layer, thus protecting the bottom face sheet, an effect that is hard to measure in experiments. All the findings provided in this chapter show that the combination of cork agglomerates core and banana fabric face sheets to form a hybrid composite system with balanced multifunctional performance [ 73 ]. Although addition of cork causes a controlled decrease in the absolute tensile strength, it imparts great gains in vibration damping (up to 267% increase in damping ratio) and impact resistance (up to 131% increase in energy absorption). The 3 mm cork core structure (L3) proves to be especially promising, which would provide the best balance of the mechanical strength that should be retained and the superior functionality characteristics. Both experimental method and the numerical modeling technique are validated by the high correlation between the experimental results and the finite element results (within 10% error range). This near match (± 8–10%) of the FEA predictions and the experimental values does not only test the characteristics of the materials, but, more significantly, the modeling approach multifaceted with the representation of a cork as a crushable foam and cohesive zone elements that are used to model an interface [ 74 ]. CONCLUSIONS AND FUTURE WORK The current chapter is a synthesis of the most important findings of the experimental and numerical study of fully bio-based banana fabric-cork agglomerate sandwich composites. It makes conclusive findings on the effect of core thickness on the mechanical, dynamic, and impact performance, which is a synthesis of the evidence introduced in Chap. 3 to assess the viability of the composite in specific engineering applications. Based on these conclusions, the chapter provides a future direction of the research. It also determines certain constraints of the current research and suggests narrow-minded directions of further research such as durability trials, interface optimization, and long-term modeling methods. It is hoped that this will shift the focus of basic characterization to practical development and that this development will give a clear guideline to the researchers and engineers to further hone, scale and use these eco-friendly composites in vibration-sensitive and semi-structural applications. 4.1. Conclusion This research studied both the mechanical and dynamic and impact performance of a fully bio-based hybrid sandwich composite using woven banana fabric face sheets and cork agglomerate cores of different thicknesses. Table VI details the summary parametric performance and characteristics of the composite. Tensile Performance: Adverse effect on tensile strength and stiffness was predictable with the addition of cork core compared to monolithic banana fabric laminates. However, the 3 mm core configuration (L3) created a compromise as it retained 67% of the monolithic ultimate tension strength and provided significant functional enhancements. Vibration Damping: The viscoelastic properties of the cork helped to make tremendous inroads in damping performance. Damping ratios of up to 267% were found due to the 6 mm core (L2), whereas the natural frequencies were found to be reduced in a ratio of 25–40% proving the effectiveness of the composite. Impact Resistance: The sandwich configurations had significantly improved impact energy absorption - with absorption as high as 131% that of the monolithic baseline - because of the progressive cell collapse of the cork core. Finite Element Validation: FE models created in Abaqus have successfully predicted global tensile, modal and impact responses to within an average error of less than 10% validating the use of such models for design optimization and parametric studies in future. Table. VI. Multifunctional Performance Summary and Trade-off Analysis of Composite Configurations Performance Metric L1 (Monolithic) L2 (6 mm Cork) L3 (3 mm Cork) Implication for Design Tensile Strength (MPa) 59.6 ± 2.1 33.5 ± 1.5 39.5 ± 1.8 Controlled reduction, L3 retains ~ 67% of L1 Specific Strength (MPa·cm³/g) 44.1 28.9 36.5 L3 offers best weight-specific performance Damping Ratio (ζ) 0.012 0.041 0.032 L2 optimal for max damping; L3 offers balance 1st Natural Freq. (Hz) 42.3 24.8 31.6 Significant shift away from common excitation Charpy Impact (kJ/m²) 4.2 9.7 8.3 Sandwich effect doubles impact resistance Primary Failure Mode Fiber pull-out Core shear/de-bond Mixed mode Failure shifts from tensile to shear-dominated Overall, the banana fabric-cork hybrid sandwich composite, especially with a 3mm core, is an environmentally friendly, multifunctional material solution that can be used in applications. 4.2 Limitations of the Present Study Work While this investigation accounts for an extensive data on the mechanical and dynamic behavior of the proposed composite, some limitations are recognized to set the result in context and point to future research. Firstly, the study samples of isotropic cork agglomerate sheets of commercial origin. The internal fluctuations of the dimensions and distribution of cork granules and the characteristics of the polyurethane binder could possibly introduce scatter into the experimental data, especially in the compression and shear-driven failure modes. Secondly, the experimental scope was limited to quasi-static tensile, impact and free-vibration tests. Performance under complex, multi-axial fatigue loading or in a controlled hygrothermal environment, which is important in many hygrothermal applications, was not evaluated. Thirdly the finite element model, though accurate in the prediction of global responses, used a simplified crushable foam plasticity model for the cork core. Finally, one type of epoxy matrix and one type of face sheet layup (two plies) was considered in the study. The interplay between various bio-based resins, different fiber structures (such as non-woven or alternative hybrid fabric) and distinct fiber volume fractions on interfacial bonding and overall performance has yet to be investigated. 4.3 Future Work Suggestions To overcome the above limitations and to further develop the competitions of sustainable bio-composite sandwiches, the following researches are proposed: Improved Durability and Environmental Testing In future tests it is necessary to study the long-term performance of the composite subjected to cyclic fatigue loads, hygrothermal aging (moisture uptake and thermal cycling), and exposure to UV radiation. Interface Engineering and Micromechanics Research should be guided towards the optimization of the face-sheet/core-interface, either by physical or chemical surface pre-treatment of the cork agglomerate mass, or by the use of toughened adhesive layers. Parallel effort should be devoted to the development of micromechanical models or multi-scale finite element models. Expanded Design Space Exploration Parametric studies based on validated models should be performed to investigate the effects of key core gradation (density or thickness gradients), hybrid cores (cork with other sustainable foam types) and other sustainable resin systems. DECLARATION OF FUNDING DECLARATION OF FUNDING The Research study/work did not received/accepted any funding. ETHICS DECLARATION The authors have declared no conflict of interest No ethics committee approval was required for this study, as the research involved exclusively material fabrication, mechanical testing, and numerical simulations. No human participants, animals, biological samples, or personal data were involved at any stage of the investigation. HAMMAD ALI Corresponding author References Peças P, Carvalho H, Salman H, Leite M (2018) Natural fibre composites and their applications: A review. J Compos Sci 2(4):66 Syduzzaman M et al (2023) Unveiling new frontiers: Bast fiber-reinforced polymer composites and their mechanical properties. Polym Compos 44(8):4455–4470 Al Rashid A, Khalid MY, Imran R, Ali U, Koc M (2020) Utilization of banana fiber-reinforced hybrid composites in the sports industry, Materials. 13(14):3167 Fan Y (2023) Mechanical properties of banana fiber composite. J Phys Conf Ser 2539:012093 Altaf H, Reza A (2024) Advancements in composite materials: Development and experimental analysis of banana and bamboo fiber reinforced polyester composites. Eur J Theor Appl Sci 2(6):466–479 Adeniyi A, Ighalo J, Onifade D (2019) Banana and plantain fiber-reinforced polymer composites. J Polym Eng 39(7):597–611 Castanie B, Bouvet C, Ginot M (2020) Review of composite sandwich structure in aeronautic applications, Compos. Part C. 1:100004Open Access Khan T et al (2020) A review on recent advances in sandwich structures based on polyurethane foam cores. Polym Compos 41(6):2355–2400 Fernandes FAO, Alves de Sousa RJ, Ptak M, Migueis G (2019) Cork composites for impact absorption. Appl Sci 9(4):735 Bouhemame N et al (2025) Impact response of new bio-sandwiches manufactured with a cork core and laminate skins based on leaflets palm date and a green epoxy resin. Int J Adv Manuf Technol 140:3379–3391 Elayaperumal A (2010) Banana fiber reinforced polymer composites - A review. J Reinf Plast Compos 29(15):2387–2396 Hidalgo-Salazar MA, Correa JP (2018) Mechanical and thermal properties of bio composites from nonwoven industrial Fique fiber mats with epoxy resin and linear low-density polyethylene. Results Phys 8:461–467 Ilyas R et al (2022) Natural fiber-reinforced polylactic acid, polylactic acid blends and their composites for advanced applications, Polymers, vol. 14, no. 1, p. 202 Othman S et al (2020) Starch/banana pseudostem biocomposite films for potential food packaging applications, BioRes. 15(2):3984–3998 Abdollahiparsa H, Shahmirzaloo A, Teuffel P, Blok R (2023) A review of recent developments in structural applications of natural fiber-reinforced composites (NFRCs), Compos. Adv Mater, 32 Kausar A, Ahmad I, Rakha SA, Eisa MH, Diallo A (2023) State-of-the-art of sandwich composite structures: Manufacturing-to-high performance applications. J Compos Sci 7(3):102 Urbaniak M, Goluch-Goreczna R, Bledzki A (2017) Natural cork agglomerate as an ecological alternative in constructional sandwich composites, BioRes. 12(3):5512–5524 Melati A et al (2024) Effect of fire-retardant coating on bamboo and banana-based bio composites: A comparative study thermogravimetric analysis and cone calorimeter tests. J Thermoplastic Compos Mater 37(2):493–519 Sargianis J, Kim H, Suhr J (2012) Natural cork agglomerate employed as an environmentally friendly solution for quiet sandwich composites. Sci Rep 2:403 Dymek M et al (2024) Eco-friendly cork-polyurethane bio composites for enhanced impact performance: Experimental and numerical analysis, Polymers, vol. 16, no. 7, p. 887 Mujahid Y, Sallih N, Mustapha M, Abdullah MZ, Mustapha F (2020) Effects of processing parameters for vacuum-bagging-only method on shape conformation of laminated composites, Processes, vol. 8, no. 9, p. 1147 Asyraf MRM et al (2022) Product development of natural fibre-composites for various applications: Design for sustainability, Polymers, vol. 14, no. 5, p. 920 Awad SA et al (2026) Performance enhancement of hybrid kenaf/bamboo fibre-reinforced bio-epoxy composites for sustainable structural applications. J Mater Res Technol 41:29–38 Francucci G, Palmer S, Hall W (2017) External compaction pressure over vacuum-bagged composite parts: Effect on the quality of flax fiber/epoxy laminates. J Compos Mater 52(1):3–15 Kubiś M et al (2018) Experimental and numerical investigation on the impact of vacuum level on effective thermal conductivity and microstructure of carbon fibre reinforced epoxy composites manufactured by vacuum bag method. 240:01015MATEC Web Conf. Serra GF et al (2025) Multilayered cork composites for safety purpose in E-micromobility. In: Gürgen S (ed) Guarding with Cork. Springer, Cham, pp 55–70 Saaidia A, Belaadi A, Haddad A (2022) Moisture absorption of cork-based biosandwich material extracted from Quercus suber L. Plant: ANN and Fick's modelling. J Nat Fibers 19(16):12486–12503 Gozdecki C, Moraczewski K, Kociszewski M (2023) Thermal and mechanical properties of biocomposites based on polylactide and tall wheatgrass, Materials. 16(21):6923 Butt MS et al (2024) Shaping sustainable pathways: Enhancing mechanical properties of biocomposite through tannic acid treatment of flax fabrics. Int J Biol Macromol 266:131393 Shanmugam V et al (2021) Circular economy in biocomposite development: State-of-the-art, challenges and emerging trends, Compos. Part C, Open Access, vol. 5, p. 100138 Ong M, Silva A (2024) Effects of low-velocity-impact on facesheet-core debonding of natural-core composite sandwich structures-A review of experimental research. J Compos Sci 8(1):23 Suriani MJ et al (2021) Critical review of natural fiber reinforced hybrid composites: Processing, properties, applications and cost, Polymers, vol. 13, no. 20, p. 3514 Krishnasamy S, Nagarajan R, Thiagamani SMK, Siengchin S (eds) (2021) Mechanical and Dynamic Properties of Biocomposites. Wiley Hidayat S (2018) Int Influence of the vacuum bag process on the strength of laminate composite, in Proc. Conf. Appl. Sci. Technol. (iCAST), Manado, Indonesia, 2018, pp. 754–757 Rodríguez LJ, Fabbri S, Orrego CE, Owsianiak M (2020) Life cycle inventory data for banana-fiber-based biocomposite lids, Data Brief, vol. 30, p. 105605 Soto-Barrera VC et al (2025) Life cycle assessment of biocomposite production in development stage from coconut fiber utilization, Sustainability, vol. 17, no. 18, p. 8338 Fitzgerald A et al (2021) A life cycle engineering perspective on biocomposites as a solution for a sustainable recovery, Sustainability, vol. 13, no. 3, p. 1160 Ilari V, Sabbatini C, Sasso M (2025) Experimental and numerical analysis of dynamic behavior of cork material, in Mechanics of Biological Systems and Materials and the Mechanics of Composite, vol 3. Hybrid & Multifunctional Materials, pp 51–58 Popineau V et al (2021) Vacuum-bag-only (VBO) molding of flax fiber-reinforced thermoplastic composites for naval shipyards. Appl Compos Mater 28:791–808 Kaufmann J, Temesgen AG, Cebulla H (2025) A comprehensive review on natural fiber reinforced hybrid composites processing techniques, material properties and emerging applications. Discov Mater 5:227 Azman MA et al (1917) Natural fiber reinforced composite material for product design: A short review, Polymers, vol. 13, no. 12, p. 2021 Dong X et al (2023) Effect of infusion strategy on vacuum bagging process and properties of polyamide 6 composites. J Polym Res 30:137 Yang YH, Young WB (2021) Carbon/epoxy composites fabricated by vacuum consolidation of the interleaved layup of prepregs and dry fibers. Fibers Polym 22:460–468 Dhal M et al (2026) Valorization of hardwood sawdust as a reinforcing filler in melt-extruded poly (lactic acid) based composites using silly putty as a plasticizing additive. J Polym Res 33:17 Chien M et al (2026) Material properties, characterization, and application of microcellular injection-molded polypropylene reinforced with oyster shells for Pb(II) adsorption kinetics from aqueous solutions, Polymers. 18(1):110 Lin C-H, Dahy H (2026) Introducing tailored fiber placement (TFP) as a sustainable fabrication method for architecture: Four case studies in mold-less and integrative construction, Buildings. 16(1):193 Phunpeng V, Saensuriwong K, Kerdphol T (2022) Comparative manufacturing of hybrid composites with waste graphite fillers for UAVs, Materials. 15(19):6840 Hassan MZ et al (2020) Impact damage resistance and post-impact tolerance of optimum banana-pseudo-stem-fiber-reinforced epoxy sandwich structures. Appl Sci 10(2):684 Reis P, Silva M, Santos P, Parente J, Bezazi A (2020) Viscoelastic behaviour of composites with epoxy matrix filled by cork powder. Compos Struct 234:111669 Alsufyani T, M'sakni NH, Part A (2023) Biodegradable bio-composite film reinforced with cellulose nanocrystals from Chaetomorpha linum into thermoplastic starch matrices, Polymers. 15(6):1542 Simona M, Bălțatu et al (2025) Biocomposites: Materials, properties, and applications, IntechOpen Lima EMB et al (2021) Biocomposites of PLA and mango seed waste: Potential material for food packaging and a technological alternative to reduce environmental impact. Starch - Stärke 73:5–6 Evaluation of the physico- (2023) mechanical characteristics of composites using banana fiber: In-depth review findings. Int J Adv Sci Eng 9(3):2961–2972 Bahrami M, Abenojar J, Martínez MÁ (2020) Recent progress in hybrid biocomposites: Mechanical properties, water absorption, and flame retardancy, Materials, vol. 13, no. 22, p. 5145 Sekar S, Kumar SS, Vigneshwaran S, Velmurugan G (2022) Evaluation of mechanical and water absorption behavior of natural fiber-reinforced hybrid biocomposites. J Nat Fibers 19(5):1772–1782 Baysal A, Yayla P, Turkmen HS, Karaca Ugural B (2023) Mechanical characterization of hybrid biocomposites reinforced with nonwoven hemp and unidirectional flax fibers. Polym Compos 44(6):3555–3566 Kuram E (2022) Hybrid biocomposites: Utilization in aerospace engineering. In: Mazlan N, Sapuan S, Ilyas R (eds) Advanced Composites in Aerospace Engineering Applications. Springer, Cham, pp 271–290 Fadhil HS, Hamad QA, Oleiwi JK (2025) Fabrication and biological evaluation of bio-epoxy hybrid composites reinforced with flax, glass, carbon, and polyethylene fibers for bone plate applications. Ann Chim - Sci Mat 49(2):187–193 Al-Allaq A, Kashan JS, El-Wakad MT, Soliman AM (2021) Evaluation of a hybrid biocomposite of HA/HDPE reinforced with multi-walled carbon nanotubes (MWCNTs) as a bone-substitute material. Mater Tehnol 55(5):673–680 Gaulke E, Garcia MCF, Schneider ALDS, Pezzin APT (2023) Hybrid biocomposite based on bacterial cellulose with hydroxyapatite partially substituted by Mg/Zn and Mg/Sr for guided bone regeneration, in Proc. ABPMt., pp. 1047–1051 Ramírez GM, Lopez Gonzaleznúñez RG, Moscoso Sánchez FJ, Rodrigue D, González-Núñez R (2025) Hybrid biocomposites based on PLA/pine fiber/CaCO3. Int Polym Process 40(5):623–635 Belaadi A, Saaidia A, Boumaaza M, Alshahrani H, Bourchak M (2023) Modeling moisture absorption of flax/sisal reinforced hybrid biocomposites using Fick's and ANN methods. J Nat Fibers, 20, 1 Sachcha IH et al (2024) Development of eco-friendly biofilms by utilizing microcrystalline cellulose extract from banana pseudo-stem, Heliyon. 10(7):e29070 Fernández MV et al (2023) Mechanical characterization of a polymer/natural fibers/bentonite composite material with implementation of a continuous damage model. Appl Sci 13(4):2677 Ai B et al (2021) Biodegradable cellulose film prepared from banana pseudo-stem using an ionic liquid for mango preservation. Front Plant Sci 12:625878 Le Duigou A, Chabaud G, Matsuzaki R, Castro M (2020) Tailoring the mechanical properties of 3D-printed continuous flax/PLA biocomposites by controlling the slicing parameters, Compos. Part B, Eng., vol. 203, p. 108474 Sucinda EF et al (2021) Development and characterisation of packaging film from Napier cellulose nanowhisker reinforced polylactic acid (PLA) bionanocomposites. Int J Biol Macromol 187:43–53 Sałasińska K et al (2022) The effect of manufacture process on mechanical properties and burning behavior of epoxy-based hybrid composites, Materials. 15(1):301 Samuel BO, Sumaila M, Dan-Asabe B (2022) Manufacturing of a natural fiber/glass fiber hybrid reinforced polymer composite (PxGyEz) for high flexural strength: an optimization approach. Int J Adv Manuf Technol 119:2077–2088 Sadroddini M (2025) Enhanced mechanical and thermal properties of polyester/glass/sheep wool fiber hybrid composites by successful replacement glass with wool. Sci Rep Khan T et al (2025) Prediction of the tensile properties of biocomposites: a review of micro-mechanical models. Biomass Conv Bioref 15:13123–13141 Lim LJY, Jamil SNAM, Rejab MRM (2024) Dynamic mechanical analysis of natural fiber composites: A review of recent findings. Polym Test 128:108234 Montoya Berrio J, Negrete Martínez J, Suárez A (2024) Influence of drying temperature on the properties of Colombian banana fibers for its potential use as reinforcement in composite materials. Sci Rep 14:25180. https://doi.org/10.1038/s41598-024-76460-4 Lopes H, Silva S, Machado J (2020) Analysis of the Effect of Shape Factor on Cork–Rubber Composites under Small Strain Compression. Appl Sci 10(20):7177. https://doi.org/10.3390/app10207177 Additional Declarations The authors declare no competing interests. Supplementary Files GA.png GRAPHICAL ABSTRACT Cite Share Download PDF Status: Posted Version 1 posted 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-8935058","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":594947682,"identity":"2286c37d-507e-4432-93a7-46172f6d1331","order_by":0,"name":"Hammad Ali","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIiWNgGAWjYJCCAw8YLHgMwEw2GyDB2HiAoJYEBgmYljSQlgaCWhiAWhigWg5DDMGnml/s8MMDCTUSMubsp1M3/Cg7b7e2/TDQlhqbaFxaJGenGRxIOCbBY9mTu+1mz7nbydvOJAK1HEvLbcChxeB2AlALG9AvB3K33eBtu51sdgCohbHhME4t9rfTPxxI+AfUcv7ttpt/284lm51/iF+LgXSOwYHENqCWG7nbbvO2HbAzu0HAFonbOQUHEvtAWt5uuy1zLjnB7AbQlgQ8fuGfnb75w4dvNvYG54Hef1NmZ292Pv3hgw81Nji1YIBEsMoEYpWDgD0pikfBKBgFo2BkAADtmGvJN58O+QAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0009-0001-0189-3950","institution":"Ghulam Ishaq Khan Institute of Engineering Sciences and Technology","correspondingAuthor":true,"prefix":"","firstName":"Hammad","middleName":"","lastName":"Ali","suffix":""}],"badges":[],"createdAt":"2026-02-21 17:55:08","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-8935058/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8935058/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103505863,"identity":"2c11e56b-678d-4b8d-862d-fa383a5066eb","added_by":"auto","created_at":"2026-02-26 13:33:17","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":179638,"visible":true,"origin":"","legend":"\u003cp\u003eRectangular Cutout from banana fabric roll to be employed as top-bottom plies.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/84be33ba9238a4fe7648c9ed.jpg"},{"id":103284495,"identity":"9c39fb66-fff8-499d-a7a5-4a416b7611c3","added_by":"auto","created_at":"2026-02-24 04:14:09","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":370794,"visible":true,"origin":"","legend":"\u003cp\u003eCork Agglomerate Sheet to employ as core material in epoxy matrix.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/f90ca542aef132754cdfed5d.jpg"},{"id":103505899,"identity":"1c8f0e2f-165c-4994-af7d-53e9bf7a89e1","added_by":"auto","created_at":"2026-02-26 13:33:25","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":589584,"visible":true,"origin":"","legend":"\u003cp\u003ePathway sequence for fabricating Sandwich Laminates for test processing.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/48102b41fc5e31e629b7941e.png"},{"id":103505726,"identity":"f157f621-4968-4979-b9a5-cffb2ffec48a","added_by":"auto","created_at":"2026-02-26 13:32:45","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":79954,"visible":true,"origin":"","legend":"\u003cp\u003eCharpy Impact Analysis sample specimen coupons for testing.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/c8c58c167d366cbf39bfa472.jpg"},{"id":103284492,"identity":"4ba21042-cf0f-484a-a8e3-35859051ed48","added_by":"auto","created_at":"2026-02-24 04:14:09","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":64925,"visible":true,"origin":"","legend":"\u003cp\u003eTest equipment along with standard specimen dimensions for natural decay damping.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/a2751cc9f0f93fb38187d004.png"},{"id":103506346,"identity":"beded999-d060-4d24-bbb8-2fbc311c2bb8","added_by":"auto","created_at":"2026-02-26 13:35:28","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":98462,"visible":true,"origin":"","legend":"\u003cp\u003eComparative Tension Test plot of Curves for Mechanical Strength via ASTM D3039\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/92446d38b6b85b4573380c58.png"},{"id":103505853,"identity":"06757565-8a1e-48da-859f-601c22497034","added_by":"auto","created_at":"2026-02-26 13:33:14","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":41869,"visible":true,"origin":"","legend":"\u003cp\u003eComparative plot for the three architectures against Mechanical indicators\u003cem\u003e\u003cstrong\u003e.\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/c623ee636172092a67149e83.png"},{"id":103284497,"identity":"080d98f4-d5b6-40dd-a90a-8e14df81823f","added_by":"auto","created_at":"2026-02-24 04:14:09","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":41197,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative comparison plot for L1, L2, and L3 decay profiles.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/48cad247079ac2d9bf886944.png"},{"id":103284499,"identity":"afc268ca-f09d-4b72-aa56-2aec659fafd7","added_by":"auto","created_at":"2026-02-24 04:14:09","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":134186,"visible":true,"origin":"","legend":"\u003cp\u003ePlot of comparison for impact performance obtained from FEA and Experiment.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/be9118eed388d7da35ae427f.png"},{"id":104397678,"identity":"c8256354-faa2-49ad-9fa0-dbb408b7d538","added_by":"auto","created_at":"2026-03-11 11:54:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3322546,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/48ffdfeb-fc80-4cf7-a92b-c8aa228a0d7c.pdf"},{"id":103505550,"identity":"3d958d43-6404-487c-9ff3-2a5fef21e6f5","added_by":"auto","created_at":"2026-02-26 13:31:44","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":684557,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGRAPHICAL ABSTRACT\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"GA.png","url":"https://assets-eu.researchsquare.com/files/rs-8935058/v1/998aa21d51b3c212ff25d566.png"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eMechanical and Dynamic Behavior of Banana/cork Sandwich Structures: An Integrated Experimental and Finite Element Study\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eSustainable engineering solutions, necessitated by the need to minimize environmental impact coupled with preservation or improvement of structural performance, has become a major paradigm in materials science. In this respect, natural fiber-reinforced polymer (NFRP) composites have become potential alternatives to their synthetic analogs in different structural and semi-structural applications. Nevertheless, dynamic performance, especially vibration damping and impact resistance which are needed in components that have to work in the dynamic loading environment is usually a constraint to the widespread use of monolithic NFRP. A good principle to counter these constraints is the sandwich construction principle, where the stiff and strong face sheets are mixed to form an energy absorbing, and lightweight core. In this paper, we examine how to develop and characterize a completely bio-based hybrid sandwich composite, which is innovatively made of woven banana fabric face sheets and cork agglomerate cores. Systematic study of this sustainable material system mechanical, dynamic, and impact performances is conducted, and the results are verified with the help of a finite element (FE) model. Background and Motivation\u003c/p\u003e \u003cp\u003eThe fact that sustainability and environmental responsibility is continually gaining momentum has led to heightened interest in replacing synthetic fiber-reinforced polymer composites with natural fiber-reinforced polymers (NFRP) in structural and semi-structural product use. It has been endorsed in literature that NFRPs also have certain benefits that include the low density, renewability, low environmental impact, and competitive specific mechanical properties [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Banana fiber is one of the natural fibers which have attracted interest because of their broad availability, good tensile indicators and can be used in woven and textile-based reinforcement architecture [\u003cspan additionalcitationids=\"CR6 CR7\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough banana fiber fabric has these benefits, monolithic natural fiber composites can be regularly constrained by rather low vibration damping and impact resistance that curtail their applications in vibration-sensitive and dynamic loading conditions [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Some common biobased material candidates with their key mechanical properties and performance characteristics. In order to address these shortcomings, sandwich composite designs in which lightweight and energy-absorbing cores are used are widely studied [\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. In these types of structures, the overall in-plane loads are supported by rigid face sheets with compliant cores assisting in dissipating energy as well as the dampening of vibrations and resistance to impact [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003e1.2 Related Work and Research Gap\u003c/h2\u003e \u003cp\u003eCork agglomerate has also proved a highly interesting bio-based core material as it possesses a closed-cell structure, the viscoelastic behavior, low density, and good energy absorption property [\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. A few studies have established that cork cores offer considerable benefits in vibration damping, impact and sounding when used in sandwich structures especially with synthetic face sheets [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Simultaneously, it has been noted that sandwich composites with a polymeric or foam core combined with natural fiber face sheets represent a promising alternative [\u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] to lightweight and sustainable material classes.\u003c/p\u003e \u003cp\u003eOne of the most popular methods to forecast the mechanical and dynamic behavior of sandwich composites is finite element (FE) modeling, which has been applied to justify experimental studies [\u003cspan additionalcitationids=\"CR28\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. However, the FE methods have not reached the natural fiber-cork hybrid systems because of the heterogeneity of materials, the variability of the interfaces, and the lack of certainty concerning effective material properties already observed in the past literature [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe research work is aimed at examining the mechanical, dynamic and impact performance of a hybrid sandwich composite made of woven banana sheets, and cores of cork agglomerate of different thicknesses under the vacuum bagging process. Tensile testing through experiments, free-decay vibration testing, modal testing and Charpy and Izod impact tests are done to measure the impact of cork core thickness on structural behavior.\u003c/p\u003e \u003cp\u003eThe main contributions of the work are three-fold:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eProduction of a bio-based cork sandwich banana fabric-cork sandwich composite entirely manufactured using an industry-relevant vacuum bagging process;\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eA thorough experimental investigation of tensile, dynamic and impact behavior with specific focus to vibration damping performance; and\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eConfirmation of a model framework of a finite element framework that has the capacity to forecast global mechanical and modal response.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cp\u003eThe results of the research present design-applicable information on the sustainable sandwich composites and creates a basis on the application of the research in the vibration-sensitive and sustainability-driven engineering systems.\u003c/p\u003e \u003cp\u003eTo meet these goals, a complete bio-based hybrid sandwich composite was created where the face sheets were composed of woven banana fabric and the core constituted of cork agglomerate sheets (3 mm and 6 mm thick) where the epoxy matrix bonded everything using the vacuum bagging method as posited in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Tensile testing (ASTM D3039), free-decay vibration analysis, modal vibration testing and Charpy and Izod impact tests were used as experimental investigation to assess the mechanical, dynamic and impact performance. Also to simulate the overall mechanical and dynamic responses, Finite Element (FE) models have been created in Abaqus, which offer a justifiable numerical model as a basis of predictive design. It is a combined experimental-numerical method that not only confirms the feasibility of the proposed sustainable composite system but also provides practical facts of applying them to the vibration-sensitive and semi-structural fields.\u003c/p\u003e \u003cp\u003eIt is a reliable experimental-numerical study that provides a proven guide to the design and implementation of sustainable sandwich composites in the vibration-sensitive jobs [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The findings affirm the viability of banana fabric-cork hybrid systems and prove the possibility of reproducing the manufacturing and modeling protocol of the future development of bio-based composites [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e], [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. The subsequent chapters provide the materials, methodology of the experiment, and results, which support these contributions.\u003c/p\u003e \u003c/div\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eThis paper incorporated both experimental research and numerical assessment to develop and investigate a novel fully bio-based sandwich composite. The plan included: (i) identification and definition of sustainable materials (ii) an elaborated and optimized vacuum-bagging fabrication (iii) the manufacturing of three different composite configurations to compare them (iv) a complete set of mechanical, dynamic, and impact tests (v) checking and validating finite-elements to forecast the behavior of the material. Such a methodical practice was supposed to provide the guarantee of reproducibility, to give solid performance statistics, and to present a predictive design tool of such a type of sustainable materials [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Materials and Specifications\u003c/h2\u003e \u003cp\u003eThe material system is a fully bio-based system composed of hybrid sandwich composite that was developed and delivers the functional requirements of semi-structural applications and goal sustainability.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.1.1. Banana Fabric Face Sheets\u003c/h2\u003e \u003cp\u003eThe primary reinforcement was plain-weave banana thread (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) depicts the fabric. It is made of cotton warp, 100% banana-weft. This design provides a relative balance between drapeability and handling during lay-up. The fabric weighs 231.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 g/m\u0026sup2;. According to supplier data that has been validated by previous research, fibers contain a healthy lot of cellulose, this provides them with tensile strength of 500\u0026ndash;700 MPa and Young\u0026rsquo;s modulus of 12\u0026ndash;20 GPa [\u003cspan additionalcitationids=\"CR38\" citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThese important technical characteristics, including yarn count as well as tensile strength in warp and weft directions can be found in Table I.\u003c/p\u003e \u003cp\u003e \u003cb\u003eTable. I. Key Technical Properties of the Banana Fiber Fabrics (courtesy of PCSIR and The Natural Fibers Company.).\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSr.#\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMethod Used\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUnits\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eResults\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUncertainty\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e1.\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFiber Composition (warp/weft)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eISO-1833-11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eWarp Yarn 100% Cotton Fiber\u003c/p\u003e \u003cp\u003eWeft Yarn 100% Banana Fiber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.000692%\u003c/p\u003e \u003cp\u003e\u0026plusmn; 0.00069 %\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2.\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTensile Strength (warp/weft)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eISO-13934-1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eWarp\u0026thinsp;=\u0026thinsp;121.46\u003c/p\u003e \u003cp\u003eWeft\u0026thinsp;=\u0026thinsp;246.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;43.28 N\u003c/p\u003e \u003cp\u003e\u0026thinsp;\u0026plusmn;\u0026thinsp;18.66 N\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3.\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCount of Yarn (Weft)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eISO-7211-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.15 Tex\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e4.\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCount of Yarn (Warp)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eISO-7211-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e27.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.15 Tex\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e5.\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWeight of Fabric (GSM)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eISO-3801\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eg/m\u0026sup2;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e231.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.216 g/m\u0026sup2;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003cem\u003eNote: Testing Performed at Temperature of 20\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C and Relative Humidity of 65\u0026thinsp;\u0026plusmn;\u0026thinsp;4%\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFor the sustainable composite system, we selected this material over other bast fibers, i.e. flax or jute, because of its high specific strength and natural origin [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.1.2. Cork Agglomerate Core\u003c/h2\u003e \u003cp\u003eIt was a core made of commercial cork agglomerate sheets (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.). These consist of cork granules that are expanded and bonded together using a polyurethane-based adhesive. We tested two nominal thicknesses L3 (3mm) and L2 (6mm). The density of all samples was stable at 200\u0026thinsp;\u0026plusmn;\u0026thinsp;5 kg/m\u003csup\u003e3\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe above properties make it a perfect bio-based core in vibration attenuation [\u003cspan additionalcitationids=\"CR42\" citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. The key core properties that are summarized in table iii, there is a compressive strength of approximately 1.35 MPa, and a deformation recovery that exceeds 90%.\u003c/p\u003e \u003cp\u003e \u003cb\u003eTable. II. Technical details of the cork agglomerate sheet (courtesy of Adenwalla Sons. Ltd.).\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabb\" border=\"1\"\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProperty\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTest method\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eResult\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBlock dimensions (manufacturing)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eManufacturer spec\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e960 \u0026times; 640 \u0026times; 200 mm\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDensity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eASTM D 1752-18; ASTM D 545\u0026thinsp;\u0026minus;\u0026thinsp;23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200 kg\u0026middot;m⁻\u0026sup3; \u0026plusmn; 5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCompression to 50% thickness\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eASTM D 1752-18; ASTM D 545\u0026thinsp;\u0026minus;\u0026thinsp;23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.35 MPa (196 psi)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRecovery after 50% compression\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eASTM D 1752-18; ASTM D 545\u0026thinsp;\u0026minus;\u0026thinsp;23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;90% of original thickness\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTensile strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eISO 7322\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;2000 kPa\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.1.3. Epoxy Matrix System\u003c/h2\u003e \u003cp\u003eOur matrix was a two-part low-viscosity epoxy, which is Ressichem Zepoxy. It was selected because it is compatible with natural fibers, cures at room temperature and has a viscosity range of 500\u0026ndash;1000 CPs at 25\u0026deg;C. This type of viscosity enables the resin to impregnate the banana cloth and reach the core of the cork without excess resin [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe epoxy is cured with flexural strength of 56.6 MPa and compressive strength of 92.2 MPa, which is strong enough in the transfer of stress between the reinforcement and core after curing [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Fabrication Process: Vacuum Bagging\u003c/h2\u003e \u003cp\u003eThe high-quality, low-void laminate panels were manufactured with the help of a vacuum bagging process. Such a method had been selected over hand lay-up due to the superior pressure of the consolidation process and was also used to produce more consistent fiber volume fractions and interfacial bonding strength [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e], [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1. Layup Sequence and Preparation of the Mold.\u003c/h2\u003e \u003cp\u003eBanana Fabric- Cork Core -Banana Fabric. The mold used was made of a flat glass plate on which polyvinyl alcohol (PVA) release agent was spread. The pieces of banana fabrics were cut 310 x 310 mm and the cork core was cut 300 x 300 mm and had 5mm bleed for resin flow. Two layers of banana fabric were superimposed directly in the case of the monolithic control panel.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2. Vacuum Bagging and Curing Cycle\u003c/h2\u003e \u003cp\u003eThe lay-up was put under a perforated release film, breather cloth, and a nylon vacuum bag. The vacuum pressure was maintained at 0.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 bar, and held that way, both when infusing the resin, and in the first cure. The epoxy resin was also purged and pumped into the inlet trombone until all the fibers were saturated which was confirmed by the naked eye. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Summarizes the fabrication protocol which was created as a schedule to minimize voids, not to crush the core, and make certain that all the resin is polymerized without degrading the natural fibers [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e],[\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Configuration and Test Matrix of Composites\u003c/h2\u003e \u003cp\u003eThe effect of cork core and its thickness was separated by making three different laminate structures and testing them:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eConfiguration L1 (Monolithic): Two layers of banana fabric/epoxy (Thickness is around 2.0mm), this was used as a baseline control.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eConfiguration L2 (Sandwich- Thick Core) was Banana fabric / 6mm Core Cork / Banana fabric (\u0026agrave;pprox\u0026thinsp;~\u0026thinsp;8.2mm thick).\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eConfiguration L3 (Sandwich -Thin Core): Banana fabric / 3mm Cork Core / Banana fabric (about 5.1mm thick).\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eEach configuration had five panels that were made. These panels yielded at least five specimens of the same kind, to assure statistical relevance, and to allow variation between natural materials [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Mechanical, Dynamic testing methods\u003c/h2\u003e \u003cp\u003eMechanical and dynamic performances of the fabricated hybrid composites were assessed by the way of a complete experimental campaign. To ensure that the behavior under useful conditions was captured, tests were done under quasi-static loading, dynamic loading, and impact loading.\u003c/p\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e2.4.1. Tensile Testing\u003c/h2\u003e \u003cp\u003eQuasi -static tensile tests were performed following ASTM D3039 [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e] on a universal testing machine (Shimadzu AG-X Plus) with 30 kN load cell. A crosshead speed of 2mm/minute and rectangular coupons (250mm25x8.14mm) were tested. The ultimate tensile strength (UTS), Young modulus (E), and failure strain were measured. Figure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e. shows universal testing machine with mounts and fixtures accommodated to perform mechanical tensile testing according to various ASTM, ISO, and many other standardized protocols under regulated conditions.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003e2.4.2. Impact Testing\u003c/h2\u003e \u003cp\u003eCharpy (unnotched) and Izod impact resistance tests were carried out to determine the toughness of the material and its ability to absorb energy at high-rate loading. A pendulum impact tester (Instron Ceast 9340) was tested. The impact specimens are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eCharpy Impact: This test was carried out as per ISO 179-1 [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e] on specimens (80 x 10 x 8.14 mm) as shown in. The calculated impact strength (kJm2) and impact energy (in Joules) were then measured.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eIzod Impact: Tests were performed as per ASTM D256 [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e] on notched samples (63.5 x12.7 x 8.14 mm).\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e2.4.3. Dynamic Mechanical Analysis:\u003c/h2\u003e \u003cp\u003eIn Free-Decay and Modal Testing, the properties of the vibration damper were tested by two conflicting methods. In Free -Decay Test, Cantilever beam specimens (200x20 mm) were held in place at one end and a lightweight accelerometer was applied as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Time-domain signal was used to compute the logarithmic decrement (δ) and the damping ratio (ζ) [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn Modal Analysis, an impulse hammer was used to excite the same specimens and the frequency response was recorded. The initial three natural frequencies (f\u003csub\u003e1\u003c/sub\u003e, f\u003csub\u003e2\u003c/sub\u003e, f\u003csub\u003e3\u003c/sub\u003e) and mode shapes were determined by a modal analysis software package which gives an insight into global mass distribution and stiffness [\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Finite Element Framework Model\u003c/h2\u003e \u003cp\u003eAbaqus/CAE 2020 was developed into Finite Element (FE) models to model the experimental tests and forecast the mechanical and dynamic response of the composite. The usefulness of this computational framework is that it allows optimization of banana fabric-cork sandwich composites in the future to achieve specific engineering goals as a result of experimentation. The models that were developed had a twofold role to play, not only to offer information on the location of stress distribution, initiation point of failure, and dissipation of energy that cannot easily be experimentally obtained. Second, these developed a predictive tool, proven to be reliable, to investigate design parameters outside the tested design combinations, including different density of the core or face-sheet layups.\u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e2.5.1. Model Geometry and Material Properties\u003c/h2\u003e \u003cp\u003eThree dimensional deformable parts were produced to fit in the exact size of the test specimens. The sandwich structure was modelled using a layered composite design, with plies of banana fabric being considered an orthotropic elastic material (E\u003csub\u003e1\u003c/sub\u003e, E\u003csub\u003e2\u003c/sub\u003e, v\u003csub\u003e12\u003c/sub\u003e, G\u003csub\u003e12\u003c/sub\u003e) and the material properties were obtained based on Monolithic L1 test data.\u003c/p\u003e \u003cp\u003eThe cork core was modeled as an isotropic, crushable foam taking into consideration plasticity to represent its compressive energy absorptive nature. The effect of epoxy matrix and interfacial bonding was implicitly considered through the composite section definition and cohesive zone models that were used at face-sheet/core interface and cohesive zone respectively [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e],[\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e]. The parametric setup details of simulation are detailed in table iii.\u003c/p\u003e \u003cp\u003e \u003cb\u003eTable. III. Material property inputs for Finite Element (FE) simulations in Abaqus.\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabc\" border=\"1\"\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaterial / Property\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUnits\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDescription / Source\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBanana Fabric/Epoxy Lamina (Orthotropic Elastic)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDerived from monolithic (L1) test data\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; E₁ (Longitudinal Modulus)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIn-plane, primary fiber direction\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; E₂ (Transverse Modulus)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIn-plane, perpendicular to fibers\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; ν₁₂ (Poisson's Ratio)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLiterature\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; G₁₂ (Shear Modulus)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEstimated\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCork Core (Crushable Foam Plasticity)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSupplier data \u0026amp; literature [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; Elastic Modulus, E\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInitial linear elastic slope\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; Plastic Poisson's Ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFor volumetric crushing\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; Initial Yield Stress\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStart of plastic plateau\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInterface (Cohesive Surface)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCalibrated from shear tests\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; Normal Strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTensile debonding strength\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; Shear Strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInterfacial shear strength\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e2.5.2. Simulation of Tests Tensile Simulation\u003c/h2\u003e \u003cp\u003eA static general step with an imposed displacement boundary condition was made use of. The data on stress contours and force-displacement were obtained as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. In Modal Simulation, modal shapes and frequency, the modal shapes and frequencies were obtained through a linear perturbation step (Frequency), assuming that the material is linear under the condition of small amplitude vibrations.\u003c/p\u003e \u003cp\u003eThe kinetic, internal, and total energies were followed to ensure the stability of the simulation and calculate the absorbed energy [\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e]. Tensile modulus, natural frequencies and impact energy model predictions were directly compared with experimental values to verify the modeling framework; the differences were usually limited to some 10%.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"RESULTS \u0026 DISCUSSIONS","content":"\u003cp\u003eIn this chapter, the experimental and numerical findings on three composite constructions, namely monolithic banana fabric/epoxy (L1), and sandwich structures of the 6mm (L2) and 3mm (L3) cork cores, are provided and discussed. The data are arranged such that firstly, the baseline quasi-static tensile properties are determined and then dynamic vibration response, impact resistance, followed later by confirmation of the finite element (FE) models.\u003c/p\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Tensile Properties and Failure Mechanisms\u003c/h2\u003e \u003cp\u003eTensile behavior, summarized in Table VI demonstrates the anticipated tradeoff existent between strength and functional improvement. The ultimate tensile strength (UTS) of the monolithic L1 design was maximum at 54.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32 MPa and Youngs modulus 8.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 GPa and was used as the benchmark in face-sheet performance. The stress-strain curve exhibited a linear elasticity and thereafter progressive failure which was manifested in form of pulling-out of the fibers and cracking of the matrix.\u003c/p\u003e \u003cp\u003eWhen the cork core was added to it, the mechanical response changed remarkably. Configuration L2 (6 mm cork-core) had lost 43% of the UTS (31.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8 MPa) and 26% of the modulus (6.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 GPa) to L1. This reduction is because the cork is less stiff and strong to support part of the tensile load, and has a greater likelihood of defects at the greater face-sheet/ core interface [\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e], [\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e]. The combined results of mechanical tensile tests are demonstrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eConfiguration L3 (3 mm core-cork) was a good tradeoff. It still had 67% of monolithic UTS (36.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1 MPa) and 85% of the modulus (7.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 GPa). The fact that this is an intermediate performance indicates that the thin core is sufficient in functional volume and reduces the adverse effects of a low-strength center portion as much as possible [\u003cspan additionalcitationids=\"CR62 CR63\" citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e]. Upon density correction, results of the specific tensile strength of L3 equalized that of L1 as a demonstration of the weight-saving advantage of the sandwich design to applications where absolute strength can be exchanged with multifunctionality.\u003c/p\u003e \u003cp\u003eThe reduction of the tensile strength and modulus upon insertion of cork core is entirely in agreement with the classical sandwich theory which predicts that a low stiffness core will bear only a fraction of the in-plane load. The 43% decrease in ultimate tensile strength shown by the L2 (6mm) laminate is therefore not simply due to the inculpable weakness of cork.\u003c/p\u003e \u003cp\u003eA thicker core enhances these mechanisms leading to early debonding at the interface or shearing of the core as shown by the finite - element simulations. In contrast, the L3 (3 mm) lamination shows that a thin compliant core is able to maintain an effective stress transfer between the face sheets with a relatively small penalty to the global strength. With that in view and regarding the specific strength (strength per unit of density) the L3 configuration may even exceed the monolithic laminate and thus emphasizes the weight-efficiency advantages of the sandwich layout for stiffness-driven, lightweight architectures.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Dynamic Response Mechanics\u003c/h2\u003e \u003cp\u003eThe dynamic characterization is used to measure the main function of the cork agglomerate, which is vibration damping, and the measurements of free-decay and modal testing.\u003c/p\u003e \u003cp\u003eThe free Decay tests showed that there was a significant increase in the damping ratio when cork was introduced. For L1, the damping ratio was 0.012\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0002, L2 (ζ\u0026thinsp;=\u0026thinsp;0.041), and L3 (ζ\u0026thinsp;=\u0026thinsp;0.032) had an increase in this value by 267% and 167%, respectively. The plots of log-decays (Figure. 15.) show the fast attenuation of the amplitudes in the sandwich specimens as compared to the slow attenuating monolithic laminate [\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThis strengthening is also a direct consequence of the viscoelastic nature of cork in which the amount of energy lost to friction between cells inside the cork itself and at the resin/cork interface during the cyclical straining process.\u003c/p\u003e \u003cp\u003eThe natural frequency (f\u003csub\u003e1\u003c/sub\u003e) fundamental reduced 42.30 Hz (L1) to 24.80 Hz (L2), and 31.60 Hz (L3). The decrease in the resonant frequency observed shows that the structure has become more compliant, which is beneficial toward non-resonant operational frequency redistribution, and hence vibration isolation [\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e], [\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e], [\u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e]. High damping and lower natural frequency of the sandwich designs, especially in L2, assures their higher efficiency where the design is required to provide broadband vibration suppression as in equipment casing or automotive paneling.\u003c/p\u003e \u003cp\u003eThe significant improvement in the damping ratio up to a fantastic ratio of 267% with an increasing thickness of cork is directly related to the viscoelastic energy dissipation properties of the agglomerated cork cellular structure.\u003c/p\u003e \u003cp\u003eWe have measured the phenomenon in this study and have found that there is a strong positive relationship existing between core volume, or, correspondingly, core thickness, and damping capacity.\u003c/p\u003e \u003cp\u003eSimultaneously, a reduction of 25 to 40% in the basic natural frequency represents the deliberate lowering of the global stiffness of the structure. This change has the advantage of vibration isolation, where this system replaces the resonant frequencies but the traditional conventional excitation frequencies noted in machinery or auto applications (usually in the 50\u0026ndash;200 Hz range).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Impact Response Discussion\u003c/h2\u003e \u003cp\u003eOne of the important factors that determine the damage tolerance, impact performance, showed a considerable improvement with the damage tolerance when combined with the sandwich configurations. Table VIII is a summary of Charpy and Izod impact strengths. The L1 sample (monolith) had an impact absorption of 4.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 kJ/m\u003csup\u003e2\u003c/sup\u003e. The configurations of the sandwich L2 and L3 were found to have 131% and 98% higher absorption, and measured energies of 9.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 kJ/m\u003csup\u003e2\u003c/sup\u003e and 8.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 kJ/m\u003csup\u003e2\u003c/sup\u003e respectively [\u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003eTable. IV. Impact resistance of the composite configurations.\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabd\" border=\"1\"\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConfiguration\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCharpy Impact Strength (kJ/m\u0026sup2;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIzod Impact Strength (kJ/m\u0026sup2;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eImpact Improvement vs. L1 (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eL1 (Monolithic)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e5.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eL2 (6 mm Cork Core)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e9.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e11.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u0026thinsp;131 (Charpy), +\u0026thinsp;133 (Izod)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eL3 (3 mm Cork Core)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e9.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u0026thinsp;98 (Charpy), +\u0026thinsp;92 (Izod)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eSimilar trend was seen with Izod impact experiments. This changed the logic of fracturing into a brittle fracture in 1L to ductile, energy-absorbing in the sandwich specimens. Upon impact, the cork core experiences progressive cell collapse, which offers a significant amount of energy through plastic deformation before damage is transferred to the more brittle face sheets.\u003c/p\u003e \u003cp\u003eThough L2 showed the highest absolute energy absorption, L3 showed a more balanced behavior of 98% improvement in Charpy impact resistance compared against L1, along with an equally superior tensile behavior than L2 [\u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e]. These trends strengthen the inference that the core size of 3mm represents an effectively unchallenged trade-off in multifunctional design and that it also fulfils the impact resistance, damping and residual strength requirements.\u003c/p\u003e \u003cp\u003eThe impact energy absorption mechanism that gives the sandwich structures the high impact resistance is a sequential and multi-mode mechanism. The cork core, on colliding, is sacrificial crushing layer, and goes through a series of progressive plastic cell collapse. This long compaction period takes up a lot of energy before transmission of stress waves to the bottom face sheet, which prolongs catastrophic failure. Although the L2 (6mm) core captures the largest absolute energy, the L3 (3mm). It provides 98% of the maximum impact enhancement over the monolithic base and has 67% tensile strength. This gives L3 a special application to semi-structural applications, of the type of protective panel, interior component, or casing.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Finite Element Analysis Conclusions\u003c/h2\u003e \u003cp\u003eFE models were found to have good predictive ability of global mechanical and dynamic response, as Table V shows a comparison between experimental and simulated main measures. In the tensile properties the tensile ultimate strengths and tensile moduli, projected in all configurations, were found to be within the experimental averages within the range of +\u0026thinsp;10% to -10% [\u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e], [\u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e72\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the modal analysis, the natural frequencies of the first mode of the simulation were within a range of 12% error with respect to experiment and the mode shapes of the calculation were visually consistent with the experimentally determined ones.\u003c/p\u003e \u003cp\u003e \u003cb\u003eTable. V. Comparison of Experimental Results and Finite Element Model (FEA) Predictions\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabe\" border=\"1\"\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProperty / Configuration\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eExperimental\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFEA Prediction\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAbsolute Error\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRelative Error (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTensile UTS (MPa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L1 (Monolithic)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e54.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e52.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-1.8 MPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e-3.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L2 (6 mm Cork)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e31.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e37.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u0026thinsp;5.9 MPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e+\u0026thinsp;18.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L3 (3 mm Cork)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e36.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e35.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.8 MPa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e-2.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e1st Natural Frequency, f₁ (Hz)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L1 (Monolithic)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e42.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e38.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-4.2 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e-9.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L2 (6 mm Cork)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e24.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e22.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-2.5 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e-10.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L3 (3 mm Cork)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e31.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e28.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-3.2 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e-10.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCharpy Impact Energy (J)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L1 (Monolithic)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u0026thinsp;0.02 J\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e+\u0026thinsp;6.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L2 (6 mm Cork)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u0026thinsp;0.06 J\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e+\u0026thinsp;6.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026bull; L3 (3 mm Cork)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u0026thinsp;0.05 J\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e+\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe internal development of the damage was visualized by the use of the validated model (Figure. 17.) and shows the spreading and constraint of stress waves in the cork layer, thus protecting the bottom face sheet, an effect that is hard to measure in experiments.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAll the findings provided in this chapter show that the combination of cork agglomerates core and banana fabric face sheets to form a hybrid composite system with balanced multifunctional performance [\u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e73\u003c/span\u003e]. Although addition of cork causes a controlled decrease in the absolute tensile strength, it imparts great gains in vibration damping (up to 267% increase in damping ratio) and impact resistance (up to 131% increase in energy absorption).\u003c/p\u003e \u003cp\u003eThe 3 mm cork core structure (L3) proves to be especially promising, which would provide the best balance of the mechanical strength that should be retained and the superior functionality characteristics. Both experimental method and the numerical modeling technique are validated by the high correlation between the experimental results and the finite element results (within 10% error range).\u003c/p\u003e \u003cp\u003eThis near match (\u0026plusmn;\u0026thinsp;8\u0026ndash;10%) of the FEA predictions and the experimental values does not only test the characteristics of the materials, but, more significantly, the modeling approach multifaceted with the representation of a cork as a crushable foam and cohesive zone elements that are used to model an interface [\u003cspan citationid=\"CR74\" class=\"CitationRef\"\u003e74\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e"},{"header":"CONCLUSIONS AND FUTURE WORK","content":"\u003cp\u003eThe current chapter is a synthesis of the most important findings of the experimental and numerical study of fully bio-based banana fabric-cork agglomerate sandwich composites. It makes conclusive findings on the effect of core thickness on the mechanical, dynamic, and impact performance, which is a synthesis of the evidence introduced in Chap.\u0026nbsp;3 to assess the viability of the composite in specific engineering applications.\u003c/p\u003e \u003cp\u003eBased on these conclusions, the chapter provides a future direction of the research. It also determines certain constraints of the current research and suggests narrow-minded directions of further research such as durability trials, interface optimization, and long-term modeling methods. It is hoped that this will shift the focus of basic characterization to practical development and that this development will give a clear guideline to the researchers and engineers to further hone, scale and use these eco-friendly composites in vibration-sensitive and semi-structural applications.\u003c/p\u003e \u003cdiv id=\"Sec25\" class=\"Section2\"\u003e \u003ch2\u003e4.1. Conclusion\u003c/h2\u003e \u003cp\u003eThis research studied both the mechanical and dynamic and impact performance of a fully bio-based hybrid sandwich composite using woven banana fabric face sheets and cork agglomerate cores of different thicknesses. Table VI details the summary parametric performance and characteristics of the composite.\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eTensile Performance: Adverse effect on tensile strength and stiffness was predictable with the addition of cork core compared to monolithic banana fabric laminates. However, the 3 mm core configuration (L3) created a compromise as it retained 67% of the monolithic ultimate tension strength and provided significant functional enhancements.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eVibration Damping: The viscoelastic properties of the cork helped to make tremendous inroads in damping performance. Damping ratios of up to 267% were found due to the 6 mm core (L2), whereas the natural frequencies were found to be reduced in a ratio of 25\u0026ndash;40% proving the effectiveness of the composite.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eImpact Resistance: The sandwich configurations had significantly improved impact energy absorption - with absorption as high as 131% that of the monolithic baseline - because of the progressive cell collapse of the cork core.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eFinite Element Validation: FE models created in Abaqus have successfully predicted global tensile, modal and impact responses to within an average error of less than 10% validating the use of such models for design optimization and parametric studies in future.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eTable. VI. Multifunctional Performance Summary and Trade-off Analysis of Composite Configurations\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabf\" border=\"1\"\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePerformance Metric\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eL1 (Monolithic)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eL2 (6 mm Cork)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eL3 (3 mm Cork)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eImplication for Design\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTensile Strength (MPa)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e39.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eControlled reduction, L3 retains\u0026thinsp;~\u0026thinsp;67% of L1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSpecific Strength (MPa\u0026middot;cm\u0026sup3;/g)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e36.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eL3 offers best weight-specific performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDamping Ratio (ζ)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.032\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eL2 optimal for max damping; L3 offers balance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e1st Natural Freq.\u0026nbsp;(Hz)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e31.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSignificant shift away from common excitation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCharpy Impact (kJ/m\u0026sup2;)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSandwich effect doubles impact resistance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePrimary Failure Mode\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFiber pull-out\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCore shear/de-bond\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMixed mode\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eFailure shifts from tensile to shear-dominated\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eOverall, the banana fabric-cork hybrid sandwich composite, especially with a 3mm core, is an environmentally friendly, multifunctional material solution that can be used in applications.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section2\"\u003e \u003ch2\u003e4.2 Limitations of the Present Study Work\u003c/h2\u003e \u003cp\u003eWhile this investigation accounts for an extensive data on the mechanical and dynamic behavior of the proposed composite, some limitations are recognized to set the result in context and point to future research. Firstly, the study samples of isotropic cork agglomerate sheets of commercial origin.\u003c/p\u003e \u003cp\u003eThe internal fluctuations of the dimensions and distribution of cork granules and the characteristics of the polyurethane binder could possibly introduce scatter into the experimental data, especially in the compression and shear-driven failure modes. Secondly, the experimental scope was limited to quasi-static tensile, impact and free-vibration tests.\u003c/p\u003e \u003cp\u003ePerformance under complex, multi-axial fatigue loading or in a controlled hygrothermal environment, which is important in many hygrothermal applications, was not evaluated. Thirdly the finite element model, though accurate in the prediction of global responses, used a simplified crushable foam plasticity model for the cork core. Finally, one type of epoxy matrix and one type of face sheet layup (two plies) was considered in the study. The interplay between various bio-based resins, different fiber structures (such as non-woven or alternative hybrid fabric) and distinct fiber volume fractions on interfacial bonding and overall performance has yet to be investigated.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec27\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Future Work Suggestions\u003c/h2\u003e \u003cp\u003eTo overcome the above limitations and to further develop the competitions of sustainable bio-composite sandwiches, the following researches are proposed:\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eImproved Durability and Environmental Testing\u003c/strong\u003e \u003cp\u003eIn future tests it is necessary to study the long-term performance of the composite subjected to cyclic fatigue loads, hygrothermal aging (moisture uptake and thermal cycling), and exposure to UV radiation.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eInterface Engineering and Micromechanics\u003c/strong\u003e \u003cp\u003eResearch should be guided towards the optimization of the face-sheet/core-interface, either by physical or chemical surface pre-treatment of the cork agglomerate mass, or by the use of toughened adhesive layers. Parallel effort should be devoted to the development of micromechanical models or multi-scale finite element models.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eExpanded Design Space Exploration\u003c/strong\u003e \u003cp\u003eParametric studies based on validated models should be performed to investigate the effects of key core gradation (density or thickness gradients), hybrid cores (cork with other sustainable foam types) and other sustainable resin systems.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"DECLARATION OF FUNDING","content":"\u003cdiv\u003eDECLARATION OF FUNDING\u003c/div\u003e\n\u003cp\u003eThe Research study/work did not received/accepted any funding.\u003c/p\u003e\n\u003ch3\u003eETHICS DECLARATION\u003c/h3\u003e\n\u003cp\u003e\u003cem\u003eThe authors have declared no conflict of interest\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNo ethics committee approval was required for this study, as the research involved exclusively material fabrication, mechanical testing, and numerical simulations. No human participants, animals, biological samples, or personal data were involved at any stage of the investigation.\u003c/p\u003e\n\u003cp\u003eHAMMAD ALI\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding author\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003ePe\u0026ccedil;as P, Carvalho H, Salman H, Leite M (2018) Natural fibre composites and their applications: A review. J Compos Sci 2(4):66\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSyduzzaman M et al (2023) Unveiling new frontiers: Bast fiber-reinforced polymer composites and their mechanical properties. Polym Compos 44(8):4455\u0026ndash;4470\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAl Rashid A, Khalid MY, Imran R, Ali U, Koc M (2020) Utilization of banana fiber-reinforced hybrid composites in the sports industry, Materials. 13(14):3167\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFan Y (2023) Mechanical properties of banana fiber composite. J Phys Conf Ser 2539:012093\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAltaf H, Reza A (2024) Advancements in composite materials: Development and experimental analysis of banana and bamboo fiber reinforced polyester composites. Eur J Theor Appl Sci 2(6):466\u0026ndash;479\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdeniyi A, Ighalo J, Onifade D (2019) Banana and plantain fiber-reinforced polymer composites. J Polym Eng 39(7):597\u0026ndash;611\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCastanie B, Bouvet C, Ginot M (2020) Review of composite sandwich structure in aeronautic applications, Compos. Part C. 1:100004Open Access\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhan T et al (2020) A review on recent advances in sandwich structures based on polyurethane foam cores. Polym Compos 41(6):2355\u0026ndash;2400\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFernandes FAO, Alves de Sousa RJ, Ptak M, Migueis G (2019) Cork composites for impact absorption. Appl Sci 9(4):735\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBouhemame N et al (2025) Impact response of new bio-sandwiches manufactured with a cork core and laminate skins based on leaflets palm date and a green epoxy resin. Int J Adv Manuf Technol 140:3379\u0026ndash;3391\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElayaperumal A (2010) Banana fiber reinforced polymer composites - A review. J Reinf Plast Compos 29(15):2387\u0026ndash;2396\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHidalgo-Salazar MA, Correa JP (2018) Mechanical and thermal properties of bio composites from nonwoven industrial Fique fiber mats with epoxy resin and linear low-density polyethylene. Results Phys 8:461\u0026ndash;467\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIlyas R et al (2022) Natural fiber-reinforced polylactic acid, polylactic acid blends and their composites for advanced applications, Polymers, vol. 14, no. 1, p. 202\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOthman S et al (2020) Starch/banana pseudostem biocomposite films for potential food packaging applications, BioRes. 15(2):3984\u0026ndash;3998\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbdollahiparsa H, Shahmirzaloo A, Teuffel P, Blok R (2023) A review of recent developments in structural applications of natural fiber-reinforced composites (NFRCs), Compos. Adv Mater, 32\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKausar A, Ahmad I, Rakha SA, Eisa MH, Diallo A (2023) State-of-the-art of sandwich composite structures: Manufacturing-to-high performance applications. J Compos Sci 7(3):102\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUrbaniak M, Goluch-Goreczna R, Bledzki A (2017) Natural cork agglomerate as an ecological alternative in constructional sandwich composites, BioRes. 12(3):5512\u0026ndash;5524\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMelati A et al (2024) Effect of fire-retardant coating on bamboo and banana-based bio composites: A comparative study thermogravimetric analysis and cone calorimeter tests. J Thermoplastic Compos Mater 37(2):493\u0026ndash;519\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSargianis J, Kim H, Suhr J (2012) Natural cork agglomerate employed as an environmentally friendly solution for quiet sandwich composites. Sci Rep 2:403\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDymek M et al (2024) Eco-friendly cork-polyurethane bio composites for enhanced impact performance: Experimental and numerical analysis, Polymers, vol. 16, no. 7, p. 887\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMujahid Y, Sallih N, Mustapha M, Abdullah MZ, Mustapha F (2020) Effects of processing parameters for vacuum-bagging-only method on shape conformation of laminated composites, Processes, vol. 8, no. 9, p. 1147\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAsyraf MRM et al (2022) Product development of natural fibre-composites for various applications: Design for sustainability, Polymers, vol. 14, no. 5, p. 920\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAwad SA et al (2026) Performance enhancement of hybrid kenaf/bamboo fibre-reinforced bio-epoxy composites for sustainable structural applications. J Mater Res Technol 41:29\u0026ndash;38\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFrancucci G, Palmer S, Hall W (2017) External compaction pressure over vacuum-bagged composite parts: Effect on the quality of flax fiber/epoxy laminates. J Compos Mater 52(1):3\u0026ndash;15\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKubiś M et al (2018) Experimental and numerical investigation on the impact of vacuum level on effective thermal conductivity and microstructure of carbon fibre reinforced epoxy composites manufactured by vacuum bag method. 240:01015MATEC Web Conf.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSerra GF et al (2025) Multilayered cork composites for safety purpose in E-micromobility. In: G\u0026uuml;rgen S (ed) Guarding with Cork. Springer, Cham, pp 55\u0026ndash;70\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaaidia A, Belaadi A, Haddad A (2022) Moisture absorption of cork-based biosandwich material extracted from Quercus suber L. Plant: ANN and Fick's modelling. J Nat Fibers 19(16):12486\u0026ndash;12503\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGozdecki C, Moraczewski K, Kociszewski M (2023) Thermal and mechanical properties of biocomposites based on polylactide and tall wheatgrass, Materials. 16(21):6923\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eButt MS et al (2024) Shaping sustainable pathways: Enhancing mechanical properties of biocomposite through tannic acid treatment of flax fabrics. Int J Biol Macromol 266:131393\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShanmugam V et al (2021) Circular economy in biocomposite development: State-of-the-art, challenges and emerging trends, Compos. Part C, Open Access, vol. 5, p. 100138\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOng M, Silva A (2024) Effects of low-velocity-impact on facesheet-core debonding of natural-core composite sandwich structures-A review of experimental research. J Compos Sci 8(1):23\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSuriani MJ et al (2021) Critical review of natural fiber reinforced hybrid composites: Processing, properties, applications and cost, Polymers, vol. 13, no. 20, p. 3514\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKrishnasamy S, Nagarajan R, Thiagamani SMK, Siengchin S (eds) (2021) Mechanical and Dynamic Properties of Biocomposites. Wiley\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHidayat S (2018) Int Influence of the vacuum bag process on the strength of laminate composite, in Proc. Conf. Appl. Sci. Technol. (iCAST), Manado, Indonesia, 2018, pp. 754\u0026ndash;757\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRodr\u0026iacute;guez LJ, Fabbri S, Orrego CE, Owsianiak M (2020) Life cycle inventory data for banana-fiber-based biocomposite lids, Data Brief, vol. 30, p. 105605\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSoto-Barrera VC et al (2025) Life cycle assessment of biocomposite production in development stage from coconut fiber utilization, Sustainability, vol. 17, no. 18, p. 8338\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFitzgerald A et al (2021) A life cycle engineering perspective on biocomposites as a solution for a sustainable recovery, Sustainability, vol. 13, no. 3, p. 1160\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIlari V, Sabbatini C, Sasso M (2025) Experimental and numerical analysis of dynamic behavior of cork material, in Mechanics of Biological Systems and Materials and the Mechanics of Composite, vol 3. Hybrid \u0026amp; Multifunctional Materials, pp 51\u0026ndash;58\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePopineau V et al (2021) Vacuum-bag-only (VBO) molding of flax fiber-reinforced thermoplastic composites for naval shipyards. Appl Compos Mater 28:791\u0026ndash;808\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaufmann J, Temesgen AG, Cebulla H (2025) A comprehensive review on natural fiber reinforced hybrid composites processing techniques, material properties and emerging applications. Discov Mater 5:227\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAzman MA et al (1917) Natural fiber reinforced composite material for product design: A short review, Polymers, vol. 13, no. 12, p. 2021\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDong X et al (2023) Effect of infusion strategy on vacuum bagging process and properties of polyamide 6 composites. J Polym Res 30:137\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang YH, Young WB (2021) Carbon/epoxy composites fabricated by vacuum consolidation of the interleaved layup of prepregs and dry fibers. Fibers Polym 22:460\u0026ndash;468\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDhal M et al (2026) Valorization of hardwood sawdust as a reinforcing filler in melt-extruded poly (lactic acid) based composites using silly putty as a plasticizing additive. J Polym Res 33:17\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChien M et al (2026) Material properties, characterization, and application of microcellular injection-molded polypropylene reinforced with oyster shells for Pb(II) adsorption kinetics from aqueous solutions, Polymers. 18(1):110\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin C-H, Dahy H (2026) Introducing tailored fiber placement (TFP) as a sustainable fabrication method for architecture: Four case studies in mold-less and integrative construction, Buildings. 16(1):193\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePhunpeng V, Saensuriwong K, Kerdphol T (2022) Comparative manufacturing of hybrid composites with waste graphite fillers for UAVs, Materials. 15(19):6840\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHassan MZ et al (2020) Impact damage resistance and post-impact tolerance of optimum banana-pseudo-stem-fiber-reinforced epoxy sandwich structures. Appl Sci 10(2):684\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eReis P, Silva M, Santos P, Parente J, Bezazi A (2020) Viscoelastic behaviour of composites with epoxy matrix filled by cork powder. Compos Struct 234:111669\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlsufyani T, M'sakni NH, Part A (2023) Biodegradable bio-composite film reinforced with cellulose nanocrystals from Chaetomorpha linum into thermoplastic starch matrices, Polymers. 15(6):1542\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSimona M, Bălțatu et al (2025) Biocomposites: Materials, properties, and applications, IntechOpen\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLima EMB et al (2021) Biocomposites of PLA and mango seed waste: Potential material for food packaging and a technological alternative to reduce environmental impact. Starch - St\u0026auml;rke 73:5\u0026ndash;6\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEvaluation of the physico- (2023) mechanical characteristics of composites using banana fiber: In-depth review findings. Int J Adv Sci Eng 9(3):2961\u0026ndash;2972\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBahrami M, Abenojar J, Mart\u0026iacute;nez M\u0026Aacute; (2020) Recent progress in hybrid biocomposites: Mechanical properties, water absorption, and flame retardancy, Materials, vol. 13, no. 22, p. 5145\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSekar S, Kumar SS, Vigneshwaran S, Velmurugan G (2022) Evaluation of mechanical and water absorption behavior of natural fiber-reinforced hybrid biocomposites. J Nat Fibers 19(5):1772\u0026ndash;1782\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBaysal A, Yayla P, Turkmen HS, Karaca Ugural B (2023) Mechanical characterization of hybrid biocomposites reinforced with nonwoven hemp and unidirectional flax fibers. Polym Compos 44(6):3555\u0026ndash;3566\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuram E (2022) Hybrid biocomposites: Utilization in aerospace engineering. In: Mazlan N, Sapuan S, Ilyas R (eds) Advanced Composites in Aerospace Engineering Applications. Springer, Cham, pp 271\u0026ndash;290\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFadhil HS, Hamad QA, Oleiwi JK (2025) Fabrication and biological evaluation of bio-epoxy hybrid composites reinforced with flax, glass, carbon, and polyethylene fibers for bone plate applications. Ann Chim - Sci Mat 49(2):187\u0026ndash;193\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAl-Allaq A, Kashan JS, El-Wakad MT, Soliman AM (2021) Evaluation of a hybrid biocomposite of HA/HDPE reinforced with multi-walled carbon nanotubes (MWCNTs) as a bone-substitute material. Mater Tehnol 55(5):673\u0026ndash;680\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGaulke E, Garcia MCF, Schneider ALDS, Pezzin APT (2023) Hybrid biocomposite based on bacterial cellulose with hydroxyapatite partially substituted by Mg/Zn and Mg/Sr for guided bone regeneration, in Proc. ABPMt., pp. 1047\u0026ndash;1051\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRam\u0026iacute;rez GM, Lopez Gonzalezn\u0026uacute;\u0026ntilde;ez RG, Moscoso S\u0026aacute;nchez FJ, Rodrigue D, Gonz\u0026aacute;lez-N\u0026uacute;\u0026ntilde;ez R (2025) Hybrid biocomposites based on PLA/pine fiber/CaCO3. Int Polym Process 40(5):623\u0026ndash;635\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBelaadi A, Saaidia A, Boumaaza M, Alshahrani H, Bourchak M (2023) Modeling moisture absorption of flax/sisal reinforced hybrid biocomposites using Fick's and ANN methods. J Nat Fibers, 20, 1\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSachcha IH et al (2024) Development of eco-friendly biofilms by utilizing microcrystalline cellulose extract from banana pseudo-stem, Heliyon. 10(7):e29070\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFern\u0026aacute;ndez MV et al (2023) Mechanical characterization of a polymer/natural fibers/bentonite composite material with implementation of a continuous damage model. Appl Sci 13(4):2677\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAi B et al (2021) Biodegradable cellulose film prepared from banana pseudo-stem using an ionic liquid for mango preservation. Front Plant Sci 12:625878\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLe Duigou A, Chabaud G, Matsuzaki R, Castro M (2020) Tailoring the mechanical properties of 3D-printed continuous flax/PLA biocomposites by controlling the slicing parameters, Compos. Part B, Eng., vol. 203, p. 108474\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSucinda EF et al (2021) Development and characterisation of packaging film from Napier cellulose nanowhisker reinforced polylactic acid (PLA) bionanocomposites. Int J Biol Macromol 187:43\u0026ndash;53\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSałasińska K et al (2022) The effect of manufacture process on mechanical properties and burning behavior of epoxy-based hybrid composites, Materials. 15(1):301\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSamuel BO, Sumaila M, Dan-Asabe B (2022) Manufacturing of a natural fiber/glass fiber hybrid reinforced polymer composite (PxGyEz) for high flexural strength: an optimization approach. Int J Adv Manuf Technol 119:2077\u0026ndash;2088\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSadroddini M (2025) Enhanced mechanical and thermal properties of polyester/glass/sheep wool fiber hybrid composites by successful replacement glass with wool. Sci Rep\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhan T et al (2025) Prediction of the tensile properties of biocomposites: a review of micro-mechanical models. Biomass Conv Bioref 15:13123\u0026ndash;13141\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLim LJY, Jamil SNAM, Rejab MRM (2024) Dynamic mechanical analysis of natural fiber composites: A review of recent findings. Polym Test 128:108234\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMontoya Berrio J, Negrete Mart\u0026iacute;nez J, Su\u0026aacute;rez A (2024) Influence of drying temperature on the properties of Colombian banana fibers for its potential use as reinforcement in composite materials. Sci Rep 14:25180. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41598-024-76460-4\u003c/span\u003e\u003cspan address=\"10.1038/s41598-024-76460-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLopes H, Silva S, Machado J (2020) Analysis of the Effect of Shape Factor on Cork\u0026ndash;Rubber Composites under Small Strain Compression. Appl Sci 10(20):7177. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/app10207177\u003c/span\u003e\u003cspan address=\"10.3390/app10207177\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Ghulam Ishaq Khan Institute of Engineering Sciences and Technology","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Bio-composites, Sandwich structures, Cork agglomerate, Banana fiber, Vibration damping, Modal analysis, Vacuum bagging, Sustainable materials","lastPublishedDoi":"10.21203/rs.3.rs-8935058/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8935058/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe need related to the continuous rise of sustainable structural materials with superior vibration attenuation has intensified the study of bio-based sandwich materials in recent times. To conduct this research, a hybrid sandwich composite was fabricated using woven banana fabric face sheets and cork agglomerate cores via using vacuum bagging methodology and systematically tested on its mechanical, dynamic and impact performance characteristics. Experimentally, tensile, free-decay vibration, modal vibration, Charpy and Izod impact tests were used to test the behavior of monolithic banana fabric laminates and sandwich configurations with different core cork thicknesses. Finite Element (FE) models were prepared in Abaqus to reproduce the global mechanical and dynamic response and has been compared with practical experimentation.\u003c/p\u003e\n\u003cp\u003eThe findings indicate that although the addition of cork cores causes the tensile strength to reduce in a controlled fashion, it has a considerable effect in complementing the vibration and absorption of impact energy. It was found that damping ratios had increased over 200% with increased cork core thickness and that natural frequency had decreased roughly 25-40% which signifies that the damping capability of the sample improved in terms of vibration isolation. Energy absorption due to impact was enhanced up to 40% of L2, L3.\u003c/p\u003e","manuscriptTitle":"Mechanical and Dynamic Behavior of Banana/cork Sandwich Structures: An Integrated Experimental and Finite Element Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-24 04:14:05","doi":"10.21203/rs.3.rs-8935058/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"531b909f-6705-46b5-92bd-12ecb10f7e41","owner":[],"postedDate":"February 24th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":63417067,"name":"Materials Engineering"}],"tags":[],"updatedAt":"2026-02-24T04:14:05+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-24 04:14:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8935058","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8935058","identity":"rs-8935058","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}