Fatigue Life Prediction Of Composite Laminates Based On Fatigue Master Curve

Based on the principle of time-temperature superposition,the fatigue principal curve of composite unidirectional plates is established.The stress state of composite laminates is characterized by multi-axis stress ratio.The multi-axis fatigue principal curve of composite laminates is derived.The Puck criterion is used to predict the fatigue life of composite laminates,and the fatigue life prediction model of composite materials based on the fatigue principal curve is established.The program for calculating fatigue life of composite laminates is developed.The basic physical and mechanical properties of materials are input.The fatigue life of composite laminates can be calculated by loading state and fitting parameters.Based on the finite element software ABAQUS,a progressive fatigue damage model of composite materials is established.Continuous shell element is used to characterize in-plane damage,cohesion element is used to characterize delamination damage,and user-defined subroutine UMAT is written to characterize the initiation,evolution and final failure of laminates under fatigue loading.The simulation results are compared with the existing fatigue test results in the literature,including open-cell composite laminates,open-cell composite laminates and Composite Bolted Joints under different material systems.The accuracy of the finite element model for predicting the fatigue life of different composite plates is verified.The fatigue life prediction results of the model with cohesive layer and the model without cohesive layer are compared,and the correctness of introducing delamination damage is proved by comparing with the test results.The finite element calculation results of the open-hole laminates are compared with the program calculation results and the test results,and the advantages of the two prediction methods are clarified.