Effect of Heavy Vehicle Suspension Designs on Dynamic Road Loading – A Comparative Study

In this paper road damage caused by heavy vehicles is studied. The effects of passive, semi-active and active suspension designs on dynamic road loading are compared. Attention is given to develop an accurate vehicle model with useful tandem suspension behavior. A nonlinear two-dimensional model of tractor-semitrailer is considered. The model includes nonlinear behavior of leaf spring and tandem suspension in the trailer axles. To obtain accurate results, a realistic road profile model is considered. The control scheme of the semi-active suspension system is based on the modified skyhook damper model. For the active suspension control system design, due to nonlinearity in the vehicle model, a linear quarter vehicle model is considered. Then linear quadratic optimal technique is employed to design the control law. Two road damage criteria were applied to assess the vehicle performance: The dynamic road stress factor and the 95th percentile dynamic loads. Simulation results of the vehicle model with the three suspension systems are presented. Based on the first criteria, road damage for semi-active and active suspensions compared with that of passive suspension is reduced by 4.9% and 8.1%, respectively. Also based on the 95th criteria the road damage for semi-active and active suspensions compared with that of passive suspension is reduced by 18.5% and 36%, respectively.