A model of strength degradation for glass fiber reinforced polymer composite laminates under fatigue loading

In order to overcome the shortcoming of traditional strength modeling of glass fiber reinforced polymer (GFRP) composite laminates that require a large amount of strength test data, a strength degradation model on the account of residual stiffness degradation data is proposed. First, fatigue damage growth can be described by the gradual reduction of the stiffness and strength, and damage expressed by the two degradation methods are equivalent. Second, according this assumption, the connection between the two damage indices is established, and then a four parameters strength degradation model is obtained. Finally, the proposed model is validated by the applying experimental data of GFRP laminates, and the precision of proposed model is contrasted with other four models. Verification results indicate that if the residual stiffness degradation data is known, the residual strength degradation law can be predicted by a small number of residual strength tests and the presented model has better applicability and higher fitting accuracy.