Mechanical Characterization of 3D Printed PLA: Influence Of Strain Offset – Yield Stress Values Across Different Infill Orientation in Tensile Testing And Finite Element Modelling

Computational mechanics is one of the techniques used to predict and optimize material behavior and structural performance. However, modeling a complex material model and achieving an accurate response in finite element analysis (FEA) remains a challenge. This study investigates the mechanical material properties of 3D-printed polylactic acid (PLA) by integrating tensile testing and FEA to optimize material behavior. The tensile testing was conducted on three different raster orientations (0°, 45°, and 90°) and the resultant stress-strain data were used to calibrate FEA models. For FEA non-linear material model-ing, isotropic elasticity combined with a multilinear plasticity model was used, where the yield stress values were determined by using the strain offset method. Six different strain offsets (SO), i.e., 0%, 0.007%, 0.01%, 0.02%, 0,05%, and 0,2%, were analyzed to evaluate their impact on the accuracy of FEA results against experimental results. The results high-light a significant influence of strain offset selection on the plastic region estimation and overall accuracy. The commonly used 0.2% strain offset method (SOM) significantly over-estimated the plastic region, while 0% strain offset provided the most accurate simulation response. These results emphasize the importance of selecting the correct yield stress val-ue for 3D-printed nonlinear material modeling in FEA simulations.