中文摘要：

针对车辆换挡离合器，应用热弹性不稳定性（Thermoelastic instability，TEI）理论研究其接合过程中的温度场非均匀分布问题。建立离合器接合过程的二维理论模型，采用扰动法求解系统发生TEI的临界条件。通过试验验证TEI理论对离合器温度场分布研究的适用性和临界速度的存在性。研究表明当离合器接合速度超过临界速度时，系统由于摩擦热、热应力和弹性应力等因素耦合作用而失稳，摩擦副表面温度场出现强烈的非均匀性。热点数小于5时，铜基材料临界速度小于纸基材料；热点数大于5时，铜基材料临界速度大于纸基材料。减小摩擦材料弹性模量、增大热导率以及减小对偶材料热膨胀系数，可以提高系统稳定性。

英文摘要：

During the synchronizing process, inhomogeneous temperature field of vehicular shift clutches is investigated with thermoelastic instability（TEI） theory. A two dimensional theoretical model is built and a perturbation method is selected for determining the critical condition of TEI. The TEl theory and the critical speed are testified by experiments. The result shows that the instability, which is caused by coupling effects of frictional heat, thermal stress and elastic stress, leads to a strong perturbation in the temperature field, on condition that the engaging speed exceeds the critical speed. When hot spots number is less than 5, the copper-based material is more unstable; when it is more than 5, the paper-based material is more unstable. The stability of clutches can be improved by reducing the elastic modulus, increasing the thermal conductivity of the friction material and reducing the thermal expansion coefficient of the mating material.