TRUCK SUSPENSION DESIGN TO MINIMIZE ROAD DAMAGE

The objective of the work described in this paper is to establish guid elines for the design of passive suspensions that cause minimum road d amage. An efficient procedure for calculating a realistic measure of r oad damage (the 95th percentile aggregate fourth power force) in the f requency domain is derived. Simple models of truck vibration are then used to examine the influence of suspension parameters on this road da mage criterion and to select optimal values. It is found that to minim ize road damage a suspension should have stiffness about one fifth of current air suspensions and damping up to twice that typically provide d. The use of an anti-roll bar allows a high roll-over threshold witho ut increasing road damage. It is thought that optimization in the pitc h-plane should exclude correlation between the axles, to ensure that t he optimized suspension parameters are robust to payload and speed cha nges. A three-dimensional 'whole-vehicle' model of an air suspended ar ticulated vehicle is validated against measured tyre force histories. Optimizing the suspension stiffness and damping results in a 5.8 per c ent reduction in road damage by the whole vehicle (averaged over three speeds). This compares with a 40 per cent reduction if the dynamic co mponents of the tyre forces are eliminated completely.