碳/碳化硅复合材料刹车盘/片热应力场分析

采用有限元方法分析二维正交碳纤维增强碳化硅(C/SiC)复合材料制成的汽车刹车盘/片在刹车过程中引起的非线性热力耦合行为,主要研究在强制对流和热辐射作用下刹车结构的温度变化,讨论不同材料属性对刹车温度场的影响以及在温度场和膨胀系数耦合下C/SiC刹车盘/片中热应力和形变情况。数值结果表明:在双重散热条件下需要更多时间用于降温,而垂直于刹车面的热导率分量对温度传导或者降温影响较大;对于C/SiC刹车盘/片每一次刹车行为等效于一次热应力的加载和卸载,而每次产生的热应力可能突破C/SiC的极限弹性强度引起的残余塑性形变,而这种不断累积的残余效果继而引起C/SiC刹车盘/片失效。

Analysis of Thermo-Stress Field in Automotive Brake System Made of Carbon Fiber Reinforced Silicon Carbide Composite

In this paper, the nonlinear thermo-mechanical coupling behavior in the braking process of an automobile brake system made of two-dimensional orthogonal carbon fiber reinforced silicon carbide(C/SiC)composites is analyzed by finite element method. Especially the temperature change of brake under forced convection and thermal radiation is studied, the influence of different material properties on brake temperature field and the thermal stress and deformation of C/SiC brake disc under the coupling of temperature field and expansion coefficient are discussed. The numerical results show that more time is needed to reduce the temperature under the condition of double heat dissipation, and the thermal conductivity component perpendicular to the brake surface has a great influence on the temperature conduction or cooling. For two-dimensional orthogonal C/SiC brake system, each braking behavior is equivalent to the loading and unloading of the thermal stress. And the thermal stress generated each time may break through the limit elastic strength of C/SiC and cause residual plastic deformation. This cumulative residual effect in turn causes the C/SiC brake disc to fail.