Experimental study on the bending properties and failure mechanism of 3D MWK composites at elevated temperatures

Abstract

This paper reports the effect of temperature on the bending properties and failure mechanism of 3D MWK (Multiaxial warp knitted) composites. Three-point bending experiments on composites with three fiber architectures were performed at four different temperatures. Then the effect of temperature on the load/deflection curves, bending strength and stiffness were analyzed. Macroscopic fracture morphology and SEM micrographs were also examined to understand the deformation and failure mechanism. The results show that the temperature has great impact on the bending properties of 3D MWK composites and the performance decreases significantly with the increase of the temperature. Meanwhile, the bending properties can be affected greatly by the fiber architecture and these decrease significantly with the increase of fiber orientation angle at room and elevated temperatures. Moreover, the damage and failure patterns of composites vary with the test temperature and fiber architecture. At room temperature, the composite exhibits brittle fracture feature and damages in the breakage and tearing of fibers. But at the higher temperature, the composite becomes more softened, cracked and plastic. It damages in fiber layer delaminating, matrix cracking and fiber/matrix interface debonding.