Effect of Radial Temperature Gradient on Interface Pressure of Clutch Friction Pair

Based on numerical results of temperature field and stress field, a theoretical model is built to investigate thermal flux and actual contact area of the clutch friction pair during slipping process, which is validated by continuous temperature measurements and static pressure tests. Several coefficients are introduced to express slipping process of clutch friction pair: dynamic slipping thermal deformation coefficient K_α, static uneven contact coefficient K_δ, and interface pressure perturbation coefficient K. Occurrence probability of high-pressure and high-temperature areas is greater by the smaller actual contact area which leads to a larger value of interface pressure coefficient K as well. Calculation and experiment results indicate that the actual contact area ratio ranges from 40% to 60% for copper-base friction pair with low and middle friction thermal flux, and 20% to 40% with high friction thermal flux. While the friction thermal flux reaches at or above the limit, the ratio of the actual contact area to the nominal contact area is only 10%-15%.