碳纤维／双马树脂基复合材料在热循环过程中热应力分布的数值模拟

Numerical Simulation of Thermal Stress Distribution in CF/BMI Composite Subjected to Thermal Cycles

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。

Finite element analysis was used to analyze thermal stress distribution in CF/BMI com- posite under exposure to thermal cycles. Parabolic failure criterion was used to predict the potential failure zone in composite. Birth and death element technique was used to reveal the microcracks distribution in composite induced by thermal stress. Thermal stress at composite free end zone is higher than that in inner zone, and the maximum stress locates at the fiber surface in resin-rich area of free end zone. The potential failure zones locate at free end zone with the microcracks distributed along the interface, thus leads to interracial debonding failure in composite. During the following thermal cycle, the thermal stress which is alleviated to some extent and redistributed, extends from free end zone to inner zone, thus exacerbates the degree of interracial debonding. Properties evolution of CF/BMI composite subjected to thermal cycles were investigated, showing that the interracial bond property was decreased due to the formation of microcracks along the interface. The numerical simulation results are in good agreement withthe experiment results, which reasonably expect the potential failure zone in composite and analyze the reason of decrease in interracial bond property induced by thermal cycles.