Modeling of Damage Evolution and Failure in Fiber-Reinforced Ductile Composites Under Thermomechanical Fatigue Loading

In this article, a methodology based upon micromechanical analysis of multiple damage-plasticity events is developed to predict nonlinear cyclic stress-strain response and fatigue failure of continuous fiber-reinforced metal matrix composites under cyclical thermomechanical loading. Microscopic damage-plasticity events in composite are described by fiber fracture, local cyclic plasticity of matrix and interface as well as interfacial debonding. A superposition method under the framework of shear-lag arguments is developed to analyze cyclic stress and deformation in the composites. A simulation scheme coupled with Monte-Carlo method is proposed to investigate evolution of damage-plasticity, cyclic behavior, and fatigue life of the composites. The statistic variations in fiber strength, local thermoplasticity of matrix properties, and interface characters between fiber and matrix have been taken into account. The model can predict the crossover behavior of the S-N curves observed in experiments for the in-phase and out-of-phase thermomechanical fatigue loads. The underlying mechanisms controlling the cross-over behavior have been revealed by the simulation.