Abstract

The contributions of the kinematic and dynamic properties of a Panhard rod constraint to the ride and handling performance of road vehicles with beam-axle suspensions are analyzed through study of the roll plane dynamics of a modern high-decker highway bus. A nonlinear kineto-static model of the candidate vehicle is first developed and analyzed to investigate the variations in the coordinates of the suspension roll center and the sprung mass gravity center, the effective roll stiffness as a function of the magnitude of centrifugal force excitation, roll input, vehicle load and the Panhard rod design parameters. Two roll plane dynamic models of the candidate vehicle with nine-DOF and five-DOF are then formulated and analyzed under excitations due to directional maneuvers and road irregularities, as characterized by a harmonic centrifugal acceleration, out-of-phase harmonic displacements, and random unevenness with randomly distributed phase between the right and left tracks. The simulation results show that the Panhard rod inertia and bushings represented in nine-DOF model contribute only to high frequency dynamics of the vehicle. The ride and handling performance of the candidate vehicle under transverse Panhard rod constraint, which relates to the low frequency dynamics of the vehicle is thus evaluated with the simplified five-DOF model by assessing the roll and lateral displacements and accelerations of the sprung mass. The effect of the variations in the suspension and Panhard rod properties, and the vehicle operation conditions are investigated.