用于CRH3的SiC/6061铝合金共连续复合材料制动盘在紧急制动过程中考虑气流冷却情况下的热分析

摘要

使用SiC网络陶瓷骨架增强的6061铝合金复合材料(SiCn/Al)制动盘可以减少高速列车的质量.采用有限元(FE)和计算流体动力学(CFD)方法计算在300km/h速度下实施紧急制动过程中考虑气流冷却条件下SiCn/Al制动盘的热和应力.分析制动器总成及其界面的设计特点时考虑了传导、对流和辐射这三种传热的模式.结果表明,具有较高对流系数的气流冷却不仅降低制动中的最高温度,也降低了温度梯度,因为气流加速了制动盘上较热部分的热量散失.有效的气流冷却可以减少制动盘上热斑的形成和盘体的热变形.有无考虑气流冷却时,实施紧急制动后,制动盘最高温度分别为461℃和359℃.有无考虑气流冷却时,制动盘的等效压力可分别达到269和164MPa.然而,在实施紧急制动时,制动盘表面的最大应力可能超过材料的屈服强度,这可能导致在不带冷却时制动盘的塑性损伤累积.模拟结果与实验结果相一致.%The mass of high-speed trains can be reduced using the brake disk prepared with SiC network ceramic frame reinforced 6061 aluminum alloy composite (SiCn/Al).The thermal and stress analyses of SiCn/Al brake disk during emergency braking at a speed of 300 km/h considering airflow cooling were investigated using finite element (FE) and computational fluid dynamics (CFD) methods.All three modes of heat transfer (conduction,convection and radiation) were analyzed along with the design features of the brake assembly and their interfaces.The results suggested that the higher convection coefficients achieved with airflow cooling will not only reduce the maximum temperature in the braking but also reduce the thermal gradients,since heat will be removed faster from hotter parts of the disk.Airflow cooling should be effective to reduce the risk of hot spot formation and disc thermal distortion.The highest temperature after emergency braking was 461 ℃ and 359 ℃ without and with considering airflow cooling,respectively.The equivalent stress could reach 269 MPa and 164 MPa without and with considering airflow cooling,respectively.However,the maximum surface stress may exceed the material yield strength during an emergency braking,which may cause a plastic damage accumulation in a brake disk without cooling.The simulation results are consistent with the experimental results well.