Fatigue Properties And Analysis Of Three-dimensional Woven Composites

This paper studied the fatigue properties of three-dimensional woven composites under various uniaxial cyclic loads and analyzed the fatigue damage mechanism.The tension fatigue,tension-compression fatigue on weft and warp direction and in-plane shear fatigue test plan were designed in this paper.Using optical microscope,damage on the surface were the observed in real time.S-N curves,as well as the fracture macroscopic and mesoscopic pictures were obtained.At the same time,the loading curve of the specimen in each cycle was recorded by the testing machine.Based on this,the stiffness reduction curve of the specimens were obtained,and the damage mechanism and influencing factors under various fatigue loads were analyzed based on the mesoscopic damage images of the specimen at a specific time.Finally,based on the study of fatigue model of composite laminates,an empirical model for predicting the residual stiffness of threedimensional woven composites in the fatigue process was established,and the parameters of the model were obtained by means of experimental data.The comparison and analysis with the verification test showed that the model could predict the residual fatigue life based on the current residual stiffness.