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用有限元分析方法模拟热循环过程中碳纤维/双马树脂基复合材料的热应力分布,采用抛物线屈服准则分析复合材料的潜在破坏区域,并结合有限元生死单元技术揭示复合材料在热应力作用下的微裂纹分布。结果表明,复合材料自由端处的热应力大于其内部区域,其中最大热应力位于自由端处富树脂区的纤维表面;复合材料的潜在破坏区域位于自由端沿纤维与树脂基体间的界面处,主要的损伤形式为热应力引发微裂纹导致自由端处产生界面脱粘破坏。在进一步的热循环过程中,热应力得到一定程度的缓解并重新分布,由复合材料的自由端向内部区域延伸,导致微裂纹的进一步扩展而使复合材料的界面脱粘程度加重。对CF/BMI复合材料在热循环过程中性能演化的实验结果表明,热循环效应能够引发纤维与树脂基体之间的界面处形成微裂纹,导致复合材料的界面粘接性能下降。模拟结果预期了CF/BMI复合材料在实际热循环过程中的潜在破坏区域,并解析了热循环过程中导致复合材料界面粘接性能降低的根本原因,表明模拟结果与实验结果相符。
The thermal stress distributions of carbon fiber / bismaleimide matrix composites during thermal cycling were simulated by finite element analysis (FEM), and the potential failure regions of the composites were analyzed by using the parabolic yield criterion. Combined with finite element dielectrics technology, the thermal stress of composites Microcrack distribution. The results show that the thermal stress at the free end of the composite is greater than that of the inner region, and the maximum thermal stress is located on the fiber surface of the resin-rich region at the free end. The potential damage region of the composite is located at the free end along the interface between the fiber and the resin matrix, The main form of damage to thermal stress caused by micro-cracks resulting in the free end of the interface debonding damage. In the course of further thermal cycling, the thermal stress is relieved and redistributed to a certain degree, extending from the free end of the composite to the inner region, resulting in the further expansion of the microcracks and the more debonding of the composite interface. Experimental results on the performance evolution of CF / BMI composites during thermal cycling show that thermal cycling can lead to the formation of microcracks at the interface between the fibers and the resin matrix, leading to a decrease in the interfacial adhesion of the composites. The simulation results predicted the potential damage area of CF / BMI composites during the actual thermal cycling, and analyzed the root cause of the decrease of the bonding properties of the composites during the thermal cycling. The simulation results are consistent with the experimental results.