Evaluation of fatigue in unidirectional and cross-ply laminated composites using a coupled entropy-kinetic concept

Abstract

A new approach is proposed to evaluate the fatigue life of laminated composites. It uses the concepts of kinetic strength of solid materials and fracture fatigue entropy. The kinetic strength formulation is based on Zhurkov’s model to consider the temperature and time dependence of the strength of solid materials in fatigue loading. The formulation is general and can be applied to any load ratios to predict the entropy accumulation during cyclic loading, stiffness damage, and fatigue life. Cyclic damage is considered as the expended capacity to generate entropy and the concept of fracture fatigue entropy is utilized as a failure criterion. Comparison between the predictions and experimental results on T300/EPL1012 carbon/epoxy composites shows that this model can reliably predict the fatigue life of laminated composites in a uniaxial stress state.