ABSTRACT
The damage process in composite materials occurs at different length scales, ranging from the scale of the constituents and defects (microscale ) to that of a composite structure (macroscale ). This paper develops a multi-scale mechanistic approach to fatigue damage in discontinuous-fiber polymer composites. The approach accounts for the damage mechanisms in addition to the constituents' properties and characteristics. It links these micro-features to the behavior of the composite structure through a series of scale transitions using computational techniques that are based on micromechanical modeling, a thermodynamics-based formulation and finite element analysis.