Abstract: Hot spot on the rubbing pair is one of the main failure causes of vehicular shift clutches. During the synchronizing process, the reason and the rule of development of the inhomogeneous temperature field was investigated with Thermoelastic instability (TEI) theory. A three dimensional finite element model was built and grow rates of the perturbation for various frequencies were calculated. The result shows that the thermoelastic stability can be improved by decreasing the radius of the clutch and increasing the thickness of the friction disk. When the ratio between the inner and outer radius is less than 0.6, decreasing the ratio can enhance the stability. When the half thickness of the mating disk is less than 2 mm, decreasing the thickness of the mating disk can also improve the stability.

Key words: Vehicular clutches, Thermoelastic instability, Critical speed, Structural parameters, Finite element method