Title: Role of suspension damping in enhancement of road friendliness of heavy vehicles

Authors: Subhash Rakheja, John Woodrooffe

Addresses: Centre for Surface Transportation Technology, National Research Council of Canada, U-89, Alert Road, Ottawa, ONT KIA OR6, Canada. ' Centre for Surface Transportation Technology, National Research Council of Canada, U-89, Alert Road, Ottawa, ONT KIA OR6, Canada

Abstract: The influence of linear symmetric and asymmetric suspension damping on the dynamic wheel loads transmitted to the pavement is analytically investigated through response analysis of a quarter-truck model. The vehicle models comprising linear and asymmetric suspension damping in conjunction with a linear, leaf and air spring are analysed to derive the dynamic wheel loads, and vertical vibration of the sprung and unsprung masses. While the force-displacement characteristics of the leaf-spring are characterized by a semi-empirical relation derived from the measured data, the force-displacement properties of the air spring are derived using the gas laws. The analytical model is analysed for excitations arising from a smooth as well as rough roadway to derive the influence of suspension damping on the dynamic load coefficient (DLC) and the sprung mass acceleration response. The results demonstrate a clear analogy between the DLC and the vehicle ride quality. The linear and air suspensions with damping ratio near 0.10 range can considerably reduce the DLC. The corresponding vertical acceleration response of the sprung mass in the ride frequencies (4-8 Hz), however, increases slightly with an increase in suspension damping. Although the inter-layer friction inherent within a leaf spring suspension yields considerable dissipative properties, additional light viscous damping can further reduce the DLC considerably. The suspension damping, asymmetric in compression and rebound, tends to reduce the DLC with only minimal effect on the vehicle ride vibration in the ride frequency range. The reduction in DLC, somewhat less than that realized with symmetric and linear damping, varies with the degree of asymmetry.

Keywords: articulated vehicle dynamics; articulation damping; kinematics; dynamics; simulation; yaw dynamics; lateral dynamics; suspension damping; vehicle suspensions; heavy vehicles; quarter-truck model; dynamic wheel loads; vertical vibration; force displacement; dynamic load coefficient; sprung mass acceleration response; ride quality; ride comfort; vehicle vibration.

DOI: 10.1504/IJHVS.1996.054570

International Journal of Heavy Vehicle Systems, 1996 Vol.3 No.1/2/3/4, pp.363 - 381

Published online: 18 Jun 2013 *

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