考虑纤维随机分布的复合材料热残余应力分析及其对横向力学性能的影响

建立了考虑纤维随机分布并包含界面的复合材料微观力学数值模型,模拟玻璃纤维/环氧复合材料固化过程中的热残余应力。通过与纤维周期性分布模型的计算结果进行对比,发现纤维分布形式会对复合材料的热残余应力产生重要影响,纤维随机分布情况下的最大热残余应力明显大于纤维周期性分布的情况下。研究了含热残余应力的复合材料在横向拉伸与压缩载荷下的损伤和破坏过程,结果表明:热残余应力的存在显著影响了复合材料的损伤起始位置和扩展路径,削弱了复合材料的横向拉伸和压缩强度。在横向拉伸载荷下,考虑热残余应力后,复合材料的强度有所下降,断裂应变显著降低;在横向压缩载荷下,考虑热残余应力后,复合材料的强度略有下降,但失效应变基本保持不变。由于热残余应力的影响,复合材料的横向拉伸和压缩强度分别下降了10.5%和5.2%。 

Analysis on thermal residual stress of composites with random fiber distribution and its effects on transverse mechanical properties

A micromechanical numerical model was established for composites, including the interface and taking into account random fiber distribution, to simulate the thermal residual stress of glass fiber/epoxy composites during the curing process. By comparison with the calculation results of model with periodic fiber distribution, it is found that the fiber array form has great influence on the thermal residual stress of composites, with the maximum thermal residual stress of random fiber distribution much greater than that of periodic fiber distribution. The damage and failure process of composites subjected to transverse tension and compression load including thermal residual stress were also investigated. The results indicate that the existence of thermal residual stress significantly affects the damage initiation location and progressing path of composites, weakening the transverse tensile and compressive strength of the composites. Under transverse tension load, after including thermal residual stress, the strength of the composite decreases somewhat, and the fracture strain decreases greatly; under transverse compression load, after including thermal residual stress, the strength of the composite decreases slightly, but the failure strain almost remains unchanged. Due to the effect of thermal residual stress, the transverse tensile and compressive strength of the composites decrease by 10.5% and 5.2%, respectively.