Damage evolution of 3D woven carbon/epoxy composites under the tension–compression fatigue loading based on multi damage information

Abstract

The fatigue damage mechanisms of 3D woven composites are very complex. In this work the tension–compression (T-C) fatigue damage evolution of 3D woven composites is investigated using a multi-scale method. To avoid the buckling failure during the T-C fatigue tests, a novel anti-buckling device is designed. The authors combine the macro damage information (i.e., axial stiffness and surface temperature) and the meso-damage information (i.e., detection results by synchrotron radiation computed tomography (SRCT)) to investigate the fatigue damage evolution. The results show that the T-C fatigue process can be divided into two stages. The stiffness decreases slowly in a linear form in Stage I, and then decreases rapidly to final failure in Stage II. Most of the fatigue damage occurs in Stage II. The SRCT results can reveal the damage modes in either fatigue stage, in which the warp yarn breakage is the critical damage mode.