Micromechanical analysis of spherulitic polymers in multiaxial and non-proportional fatigue crack nucleation

This study focused on understanding the fatigue response of anisotropic spherulitic polymers by employing a multiscale microscopic modeling approach. The crystal plasticity model together with the Arruda-Boyce model were used to describe the mechanical response of crystalline phase and amorphous. The fatigue behaviors and crack initiation were captured by Fatemi-Socie multiaxial criterion and continuous damage theory under multiaxial and non-proportional loading conditions. The sheaf-like structure of spherulitic polymers was considered to shed light on the anisotropic nature of fatigue failure. The results highlight the role of features of sheaf structure, e.g., initiation orientation, on the fatigue performance of spherulitic polymers, which have not been reported. The localized degradation of mechanical properties and the accumulation of fatigue damage were systematically discussed with various loading patterns. This study provided an in-depth understanding of potential fatigue mechanisms, offering robust support for fatigue resistance design in engineering applications.