Multi-scale viscoelastic damage model of short glass fiber reinforced thermoplastics under fatigue loading

Abstract

This work presents a new micromechanical fatigue damage model for reinforced thermoplastic composites. The study aims at modeling high cycle fatigue damage of a short glass fiber reinforced polyamide-66. The developed approach is a modified Mori-Tanaka method that includes coated reinforcements and microscale damage processes. The model takes into account the nonlinear matrix viscoelasticity and the damage mechanisms evolution. The latter is based on the experimental damage investigation previously performed by the authors and presented elsewhere. Damage chronologies have been proposed involving three different local processes: fiber-matrix interface debonding/coating degradation, matrix microcracking and fiber breakage. Each damage mechanism is introduced through an evolution law coupled to local stress fields computed at the microscale. The first numerical results show capability of the developed model to predict the fatigue damage accumulation of the macroscopic homogenized composite material.