Effect of temperature on bending properties and failure mechanism of three-dimensional multiaxial warp-knitted carbon/epoxy composites

Abstract

The three-point bending experiments on three-dimensional multiaxial warp-knitted carbon/epoxy composites with two fiber architectures are performed at room and elevated temperatures. Macro-fracture morphology and scanning electron microscopic micrographs are examined to understand the deformation and failure mechanism. The results show that the load–deflection curves are significantly different for different temperatures and the bending properties decrease significantly with increasing the temperature. Meanwhile, bending properties can be affected greatly by the fiber architecture and these increase significantly with the decrease of the fiber orientation angle at different temperatures. The results also show that the damage and failure patterns of composites vary with the test temperature. At room temperature, the composite exhibits brittle feature, and it damages with the breakage and tearing of fibers. At elevated temperature, the composite becomes more softened and exhibits plasticity. The damage of matrix plastic and cracking, interface debonding, and fiber layer delaminating become prominent. Moreover, the failure mechanism at room and elevated temperatures can be significantly affected by the fiber architecture.