Effect of Ply Orientation and Triaxiality on Mesh Regularization for Carbon/Epoxy Composites Through Material Parameter Estimation

The mesh size significantly affects the accuracy and computational efficiency of finite-element analysis (FEA) simulations. This study investigates mesh regularization to mitigate mesh dependency, align numerical results with experimental data, and optimize the computational time for carbon/epoxy composites. Mesh regularization was implemented using the ∗MAT_ADD_GENERALIZED_DAMAGE (MAGD) model in LS-DYNA, which incorporates a scaling factor based on the ply orientation and stress triaxiality to adjust the material failure criterion. To address the limitations of trial-and-error methods for determining scaling factors, four analytical models were developed to predict these factors as functions of element size. These predictions were validated against experimentally derived scaling factors for unidirectional carbon/epoxy composites across three ply orientations (0°, 45°, and 90°) and three stress triaxiality conditions (tension, compression, and shear) using mesh sizes ranging from 0.5 mm to 1.5 mm. The scaling factor effectively reduced the mesh dependency in the tested configurations. A clear relationship between ply orientation and mesh regularization was established; however, no definitive correlation was observed with stress triaxiality. Among the theoretical approaches, the stress degradation model yielded the most consistent predictions, although discrepancies with the experimental results indicate the need for further refinement. This study proposes integrating scaling factors into a material model as a practical approach to mesh regularization for orthotropic materials and evaluates existing theoretical models for predicting these factors.