Influence of Strain-Offset-Based Yield Definitions on the Accuracy of Finite Element Analysis of 3D-Printed PLA with Different Raster Orientations

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 nonlinear material modeling, isotropic elasticity was combined with a multilinear plasticity model, where the yield stress values were determined by using the strain offset method. Six different strain offsets (SOs), i.e., 0%, 0.007%, 0.01%, 0.02%, 0.05%, and 0.2%, were analyzed to evaluate their impact on the accuracy of the FEA results against the experimental results. The results highlight 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 overestimated the plastic region, while 0% strain offset provided the most accurate simulation response. These results emphasize the importance of selecting the correct yield stress value for 3D-printed nonlinear material modeling in FEA simulations.