A continuum damage mechanics model for fatigue and degradation of fiber reinforced materials

Objective of the present study is the definition of a continuum damage mechanics material model describing the degradation of fiber reinforced materials under fatigue loads up to final failure. Based on the linear elastic framework, a brittle damage model for fatigue conditions is derived, where the damage constitutes the only nonlinearity. The model accounts for damage effects by successive degradation of the elastic moduli. Assuming that material damage is driven by microplastic work, a stress-driven damage evolution equation is defined. For generality, a fully three-dimensional formulation on single ply level is employed. The model is implemented into a finite element program. In a validation against experimental data on filament-wound carbon fiber reinforced material, the model proves to provide a good numerical approximation of the damage during the cyclic loading history up to final material failure.