Fatigue Life Prediction of Composite Laminate Based on Stress of Fiber and Matrix of UD Composite

This study investigates fatigue life prediction methodologies to establish a fatigue life evaluation technology for composite structures. Owing to the anisotropy of composite materials, a significant difference can be observed in their fatigue lives depending on stacking sequences or load directions. The fatigue life of a composite is closely related to the fatigue properties of its fiber and matrix. Depending on the mechanical contribution of the composite, its mechanical properties as well as fatigue life characteristics vary. In this study, the S-N data of fibers and matrixes were generated based on the fatigue test results and used as the basic fatigue properties for fatigue life prediction. The principal stress of the fiber and matrix was used to predict the fatigue life of laminates with different stacking sequences. To correct the mean stress of the fatigue loads, the Goodman equation was normalized using tensile and compressive strength. A comparison of the life prediction and test results of composite laminates demonstrated that the proposed methodologies predicted the test results well.