Full-field multi-scale analyses embedding fiber-matrix interfaces in short fiber reinforced thermoplastics

This contribution presents a comprehensive full-field multi-scale modeling strategy for Short Fiber Reinforced Thermoplastics (SFRTs), with a particular focus on degradation at the fiber-matrix interfaces. The proposed approach combines nonlinear matrix behavior, cohesive interface degradation, and complex, large-scale randomized periodic Representative Volume Elements (RVEs) whose fiber orientations are derived from an experimentally determined Orientation Distribution Function (ODF). By integrating these aspects within a single framework, the model captures a level of mechanical and microstructural complexity that is rarely addressed in existing SFRT simulations. The model is applied to PA66GF30 to investigate how interface properties influence the macroscopic response of the composite in connection with the development of local damage mechanisms. Interface parameters are calibrated to reproduce experimental results, leading to good agreement with the measured overall behavior. In addition, the predicted local damage patterns are consistent with mechanisms reported in the literature, highlighting the ability of the approach to link interface degradation, microstructural morphology, and overall SFRT behavior.