Microstructure-sensitive investigation on the plastic deformation and damage initiation of fiber-reinforced polypropylene composite

This study presents a comprehensive multi-scale analysis of damage mechanisms in short fiber-reinforced polypropylene composites. The study covers different fiber orientations and loading conditions, revealing distinct contributions from each damage phenomenon. Fiber/matrix interface decohesion and crack propagation across interfaces appear to be the predominant factors leading to material failure, irrespective of fiber orientation and loading mode. Mechanical tests highlight the importance of the interface of fiber/matrix in damage initiation, with local plasticity of the matrix under quasi-static loading. One can note that fiber pull-out is the predominant phenomenon. Moreover, the same damage mechanisms have been observed under 3-point fatigue loading. The results provide valuable insights for understanding and predicting damage evolution in fiber- reinforced composites. Notably, the material undergoes a consistent sequence of damage states, irrespective of monotonic or cyclic loading, highlighting the possibility of using monotonic loading data to predict fatigue lifetime.