Evaluation of multiple damage-mode models for prognostics of carbon fiber-reinforced polymers

Damage growth models are the linchpin of model-based prognostics for aging or damaged structures. Fatigue damage growth in composites can be characterized through estimating strain energy release rates and observed through stiffness reduction in the structure. The work reported herein investigates several existing models for the estimation of strain energy release rate and reduction in effective stiffness of cross-ply laminates under multiple damage modes. These models account for coexistence of matrix cracks and delamination, and have been examined using publicaly available fatigue data on carbon fiber-reinforced polymers coupons. This study is driven by the desire to identify suitable models in a prognostic context, i.e., to predict the remaining useful life of composite laminates subject to fatigue loads. Therefore, the capability of models in estimating the strain energy release rate and in accurately describing progressive degradation of the material has been analyzed. Selected models will then be used in conjunction with modified Paris' law to predict the evolution of damage progression in cross-ply laminates.