Analysis and Optimization of Driveline Bushing for Lateral Ride Vibration under Shock Excitation

Abstract

Ride comfort is increasingly important for automobile companies due to the increasing concern of the demands of customers. Response to shock at low speed, such as single or consecutive pulse excitations from humps, are one of the greatest assessing indices of vehicle ride related to the ride comfort. This paper aims to study the effect of driveline bushing on ride vibration when the vehicle experiences shock excitation and to improve the ride quality by optimizing the bushing parameters. A vehicle level multibody dynamic model with a differential-subframe subsystem is developed and calibrated against field test data. The sensitivities of the bushing stiffness and damping coefficients are analyzed and the most influential bushing parameters on the seat rail vibration are identified. The relationship between the bushing parameters and the ride vibration is developed by a 5-level response surface design. The fitted response functions are validated and adopted as the optimization objectives. The optimized results, including the acceleration, the running r.m.s. acceleration, the jerk, the running r.m.s. jerk, the VDV and the comfort, are compared with those of the baseline vehicle. Results show that the optimized bushings significantly decrease the vibration at the driver and the rear passenger seats by approximately 50% in the lateral direction. A considerable improvement has been achieved in ride comfort that the weighted vibration at seats is reduced to a level below the median perception threshold of human being in the lateral direction.