C/SiC材质盘式制动器热-机耦合特性分析

Analysis on thermal-mechanical coupling characteristics of C/SiC disc brake

为了探究新型C/SiC材料用作小型汽车盘式制动器不同载荷条件下的温度和应力特性,文中通过ABAQUS软件建立了C/SiC制动盘的三维热-机耦合模型,对不同初始速度和制动压力下的紧急制动进行了模拟仿真研究,并与传统的HT250制动盘进行了对比。结果表明:制动片对C/SiC制动盘产生周期脉冲压力,制动过程中摩擦生热造成制动盘温度周期升降,产生正弦波动的热应力,脉冲压力和正弦波动的热应力二者耦合造成制动盘Mises应力、径向应力和周向应力呈现出周期“脉冲”和“正弦”波动变化。在制动减速度为5.56 m/s2、初始速度为60 km/h条件下,C/SiC制动盘在制动摩擦区峰值温度最高为137.3℃,峰值Mises应力、径向应力和周向应力远远小于材料强度。制动盘芯部的非摩擦区域节点承受周期波动的拉应力,是容易发生疲劳失效的关键位置。随着制动减速度的提高,C/SiC比HT250材质制动盘温升更高,但应力峰值的增幅小,具有更强的抗热衰退性能,满足紧急制动的要求。

In this article,in order to explore the temperature and stress characteristics of new C/SiC materials used in the small car's disc brake under different load conditions,ABAQUS is used to set up the C/SiC brake disc's three-dimensional ther-mo-mechanical coupling model.Efforts are made to simulate the emergency brake with different initial speeds and brake pres-sures,and the results are compared with those obtained from the traditional HT250 brake disc.It is shown that the brake pad generates the periodic pulse pressure on the C/SiC brake disc,thus causing cyclic temperature fluctuations in the brake process due to frictional heating.Also,the sinusoidal thermal stress is found.The coupling of the pulse pressure and the si-nusoidal thermal stress results in the cyclic"pulse"and"sinusoidal"variations in the brake disc's Mises stress,radial stress,and circumferential stress.When the brake deceleration is 5.56 m/s’and the initial speed is 60 km/h,the C/SiC brake disc's peak temperature in the brake friction zone is highest at 137.3 C.The peak Mises stress,radial stress,and circumferential stress are significantly lower than the material strength.The nodes in the non-frictional area at the brake disc's core experience periodic tensile-stress fluctuations,making it a critical location prone to fatigue failure.With the ever-growing brake deceleration,the C/SiC brake disc's temperature rise is higher than that of HT250,but the increase of the stress peak is minor.Therefore,it is indicated that the C/SiC brake disc has stronger resistance to thermal degradation,which meets the requirement for emergency brake.