Thermal Elastohydrodynamic Coupling Characteristics of Wet Clutch Under Time-Varying Friction Interface Parameters

Friction interface parameters of wet clutches vary with time during its sliding. The thickness of the oil film changes with the contact ratio of micro-convex peaks, providing lubrication boundary conditions. Due to the interaction of temperature, strain, and flow fields, the thermal elastohydrodynamic coupling boundary conditions alternate, resulting in complex slip characteristics. This study investigates the thermal elastohydrodynamic coupling characteristics of a vehicle wet clutch with time-varying friction interface parameters. Based on hydrodynamic lubrication and heat transfer theories, the finite element method is used to establish the thermal elastohydrodynamic coupling model of wet clutches that considers the effect of temperature on oil parameters. The thermal elastohydrodynamic coupling characteristics are analyzed by comparing variations in parameters such as oil film thickness, relative speed, controlled oil pressure, and surface roughness. A wet clutch test scheme is designed, and a multifunctional vertical friction and wear testing machine is used for validation. The accuracy of model is verified by comparing the temperature-rise performances of friction plates. The distributions of temperature, pressure, stress, and strain on the surface of friction plate under the thermal elastohydrodynamic coupling conditions are studied, revealing the slip process mechanism. This research provides a theoretical basis for the dynamic design and structural optimization of wet clutches.