Experimental and numerical investigation on tension–tension fatigue behavior of three-dimensional five-directional hybrid braided composites

• Published in: International journal of fatigue Vol. 178; p. 107975
• Main Authors: Wan, Aoshuang, Shi, Junfeng, Li, Dinghe
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2024
• Subjects: Fatigue; Hybrid braided composites; Life prediction; Mesoscale representative volume element; Progressive damage model; Life prediction; Fatigue; Hybrid braided composites; Progressive damage model; Mesoscale representative volume element
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2023.107975

•The tension–tension fatigue behavior of hybrid carbon/glass fiber reinforced 3D5D braided composites was studied by experiments. The experimental results show that the fatigue strength significantly decreases as the fatigue life increases and the stiffness gradually decreases as the loading cycles increase, which indicates that the 3D5D hybrid braided composites are sensitive to tension–tension fatigue loading.•Under tension–tension fatigue loading, matrix cracking inside the yarns and interfacial debonding between the yarns and the matrix firstly occur and propagate in the 3D5D hybrid braided composites, then matrix cracking appears in the resin-rich regions and numerous fiber breakage happens until final failure. The fatigue damage mechanisms of 3D5D braided composites are affected by the fiber hybridization, resulting from the difference between the stiffness of carbon yarns and glass yarns.•A mesoscale representative volume element (RVE) model with periodic boundary conditions and a progressive fatigue damage model was developed for the 3D5D hybrid braided composites. The mesoscale progressive fatigue damage model consists of fatigue failure criteria and material property degradation laws (including gradual and sudden degradation laws). The damage of interface between the yarns and the matrix is considered by introducing a fatigue damage cohesive model.•The numerical simulation results of fatigue life, stiffness degradation and damage progression of the 3D5D hybrid braided composites have good agreement with experiments, demonstrating the validity of the developed mesoscale progressive fatigue damage model. This paper presents an experimental and numerical investigation on tension–tension fatigue behavior of hybrid carbon/glass three-dimensional five-directional (3D5D) braided composites. Fatigue tests were carried out under the stress ratio of 0.1. The experimental results show that the fatigue strength significantly decreases as the fatigue life increases and the stiffness gradually decreases as the loading cycles increase. The fatigue life at the stress level within 35 %–50 % ultimate tensile strength (UTS) is within 4 × 103–6 × 105 cycles. The stiffness degradation before failure increases from 39 % to 58 % as the fatigue stress decreases from 50 % UTS to 35 % UTS. Under tension–tension fatigue loading, matrix cracking inside the yarns and interfacial debonding between the yarns and the matrix firstly occur and propagate, then matrix cracking appears in the resin-rich regions and numerous fiber breakage happens until final failure. The fatigue performance and damage mechanisms of braided composites are affected by fiber hybrid mode and braiding methods. Additionally, a mesoscale representative volume element (RVE) model with periodic boundary conditions and a progressive fatigue damage model was developed for the 3D5D hybrid braided composites. The numerical simulation results of fatigue life, stiffness degradation and damage progression have good agreement with experiments, demonstrating the validity of the developed model.