Fatigue life prediction of laminated composites under multiaxial fatigue loading condition by using developed continuum damage mechanics model

One of the main advantages for the increasing engineering application of composites in weight-critical structural applications is their high specific stiffness and strength. Composite materials behavior is complicated more than metallic material because of different mechanisms, damage growth rate and effect of them in each other. In this paper, a continuum damage mechanics based model is developed to simulate stiffness degradation and fatigue life prediction of laminated composites under fatigue loading conditions. Damage parameters are used to estimate the degradation of elastic properties in matrix, fiber and shear direction. The material properties of the damage evolution equations are derived by testing on 0° and 90° unidirectional plies and cross-ply laminate. To evaluate the model under multiaxial fatigue loading, arbitrary states of stress and stress ratio available results of experiments on unidirectional 90 , 0 and 30 plies under fatigue loading conditions are used. Also, to evaluate the model for composite laminates with stress concentration results of experiments of pin-loaded cross-ply laminate are used. The obtained results show the capability of proposed model in fatigue life prediction of unidirectional and cross-ply laminates under uniaxial and multiaxial fatigue loading with different states of stress.