Effect of temperature on bending properties and failure mechanism of three-dimensional braided composite

This paper reports the effect of temperature on the bending properties and failure mechanism of a three-dimensional E-glass/epoxy four-directionally braided composite. Three-point bending tests of the composite were first performed at five different temperatures. Then the effect of temperature on the load/deflection curves, bending strength and bending stiffness were analyzed. The composite samples after the bending tests were also analyzed through the macro-fracture morphology and the Scanning Electron Microscope (SEM) to understand their deformation and failure mechanism. The results have shown that the temperature has significant effect on the bending properties of 3D braided composite and its mechanical performance decreases with the increase of the temperature. At the room temperature, the composite has the highest strength and modulus. It damages with the breaking of fibers and exhibits brittle fracture feature. But at the higher temperature, the composite becomes more softened and plastic. It damages with the micro-cracks of the matrix and debonding of fibers from the matrix. It is expected that the study can provide an experimental basis for the structural design of the 3D braided composites at elevated temperatures.