Experimental validation of the VIMC-MEMC framework for predicting fracture in 3D-printed round-tip V-notched PLA plates under mixed-mode I/III loading

This study evaluates, for the first time, the applicability of a combined Virtual Isotropic Material Concept (VIMC) and Modified Equivalent Material Concept (MEMC) framework for predicting fracture behavior in 3D-printed Polylactic acid (PLA) specimens with quasi-isotropic ([0°/90°/±45°] s ) raster orientation. The specimens contain round-tip V-shaped notches with different opening angles and tip radii and are subjected to mixed-mode I/III loading. All samples are fabricated using fused deposition modeling (FDM). Due to the layer-wise manufacturing process, existence of inherent voids, and printing of material in specific angles, the printed parts exhibit anisotropic behavior, while PLA itself shows nonlinear and ductile characteristics. To account for these effects, the VIMC–MEMC approach is employed to represent the material as an equivalent linear elastic isotropic medium. The framework is combined with two stress-based criteria, namely the maximum tangential stress (MTS) and mean stress (MS) models, to estimate the notch fracture toughness (NFT). Comparison with experimental results shows that both models provide accurate predictions with similar performance. The results further indicate that prediction accuracy improves for smaller notch tip radii, while NFT increases with increasing the tip radius due to reduced stress concentration.