Abstract
To achieve a comparative study of tensile fatigue life in various three-dimensional (3D) structures, 3D orthogonal woven composite (3DOWC), off-axis 3D orthogonal woven composite (OA-3DOWC) and multiaxial 3D woven composite (M3DWC), were designed and manufactured. Tensile and fatigue tests were performed, and microcomputed tomography (Micro-CT) was utilized to observe the mesoscale structural characteristics and the fatigue fracture morphology. Finite element models were established based on the observation. Then a modified power-law fatigue damage model was used for reduction of stiffness and strength during fatigue loading process, and a normalized life model was used to predict the fatigue life at different stress levels. Comparisons were conducted with existing models to analyze their predictive accuracy. Results showed that the tensile strength of M3DWC decreased by 54.6 % compared to 3DOWC, while its fatigue performance of M3DWC was significantly improved. Additionally, OA-3DOWC had the worst tensile strength but slightly improved fatigue performance compared to 3DOWC. And for the maximum error between the prediction and experimental results for the fatigue life is 11.16 %. For the fatigue life at the same stress level, M3DWC > OA-3DOWC > 3DOWC, due to the complex crack propagation paths in the staggered fiber arrangement.
Published Version
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