Finite Element Calculation Of Fatigue Damage Model For Three-Dimensional Angle-Interlock Woven Composite Subjected To Three-Point Bending Cyclic Loading

In the layer-to-layer angle-interlock woven fabric、 warp yarns bind weft yarns of each two or more layers. The adjacent warp yarns on the same layer are of totally opposite crimp status. which induces high stability and delamination resistance. Three-dimensional angle-interlock woven composite (3DAWC) includes matrix and reinforcement.3DAWC will be damaged because of stress and environment factors during the service life, among which fatigue damage is one of the major damage modes. In this paper, the fatigue damage of one type of layer-to-layer3DAWC under three-point bending cyclic loading was investigated combining tests and Finite Element Method (FEM).The main tasks of this paper are as follows:(1) To conduct quasi-static three-point bending test and get the bending modulus. failure stress and deflection. respectively. On the basis of the failure stress. to investigate three-point bending tests at stress levels of60%,65%,70%,75%and80%with sinusoidal wave form stresses applied on the coupons. Get the S-N curve and damage modes.(2) To establish a micro-structural model in the yarn level of the3DAWC with the software of ABAQUS.(3) To get the stress distribution. important damage regions and stiffness degradation by setting the material property and boundary conditions to the model. Especially, to get the crack propagation path by setting initial cracks on the interface of warp-resin.(4) To analyze the fatigue damage by combining the FEM and experimental results. In both experiment and FEA, we obtained following contents:(1)The bending modulus, failure stress and deflection were19.51GPa,160.75MPa and8.89mm in the quasi-static three-point bending test. Fatigue life decreased with the increase of stress level.(2) The stress distribution could be easily seen in the FEM result. The top and bottom layers undertook more load than the middle layers.(3) Both the experimental and FEM results showed that the damage was investigated on the warp yarns, and mainly at the regions where weft yarns cross-over the warp yarns.(4) The stiffness degradation curve in the FEM had the same feature with the one in the experiment, but the initial bending modulus was larger than the experimental result.(5) The crack path was along the warp yarn in both experiment and FEM.The research in this paper offers a reference and support for structure designing of3DAWC. It can also be further applied to anti-fatigue design of other three dimensional textile composite materials.