Influence of tyre pressure on an urban bus transient and steady state handling performance

Abstract

The influence of the variation in the tyre inflation pressure on the steady state and transient handling dynamics of an urban bus are investigated through analysis of a three-dimensional (3D) vehicle model. A five-degrees-of-freedom handling dynamic model of the bus is formulated incorporating the non-linear models of the suspension components and the tyre. The vertical stiffness properties of the tyre are characterized through a regression model under normal load and the inflation pressure that was formulated on the basis of the laboratory measured data. The available tyre data on the cornering properties of tyres are analysed to derive a modified ‘magic formula’ for predicting the cornering properties as functions of the inflation pressure and the normal load. The proposed model responses showed reasonably good agreement with the available measured data over ranges of the inflation pressures and normal loads. The 3D handling dynamic model was subsequently analysed under sinusoidal and ramp-step steering inputs to study the influence of the tyre pressure on the steady state and transient handling responses. The results show notable influences of the tyre pressures on both the steady state and the transient handling properties.