Investigation on clearance-induced vibro-impacts of torsional system based on Hertz contact nonlinearity

Abstract

The clearance-induced vibro-impacts between the connected rotors in torsional system easily causes serious transient noise and vibration. To analyze the transient vibro-impacts of torsional system excited by a step-down torque, taking a rear-wheel-drive vehicle driveline system as an example, a 7 degree-of-freedom lumped parameters model with new piecewise nonlinear clearance elements is established based on nonlinear Hertz contact theory. The transient vibro-impact phenomena of the vehicle driveline system during fast disengagement of the clutch are numerically simulated. The phase plane reveals the phenomenon of multiple impacts and rebounds in each transient impact, and shows the relationship between the relative contact displacement and velocity. The vibro-impact force and time-frequency response of linear contact stiffness model and Hertz contact stiffness model are analyzed and compared. Compared with the widely used clearance element with piecewise linear stiffness, the clearance element with piecewise nonlinear stiffness can better capture the transient vibro-impact forces and time-varying frequency responses between the driving and driven rotors. The vibro-impact results are verified by the vehicle driveline experiments.