Handling and ride comfort optimisation of an intercity bus

In this work the handling and ride comfort characteristics of an inter-city bus have been optimised. A rigid body simulation model of the bus has been used to evaluate the handling in terms of gain and time-lag of the yaw rate response due to a sinusoidal steering wheel input. A similar model but with a flexible bus body structure has been used to calculate the transient response due to obstacles on the road. The resulting discomfort within the bus has been evaluated in terms of vibration dose values according to the ride comfort standard ISO 2631:1997 at three locations within the bus. Both models have been validated against measurements. The stiffnesses of the bellows, the diameters of the anti-roll bars and the characteristics of the shock absorbers have been used as design variables in the optimisations. The results show that it is possible to improve the current ride comfort and handling characteristics of the bus by optimising the wheel suspension. It was, furthermore, shown that the handling and ride comfort criteria used in this study are in conflict with each other and a multi-criteria approach was therefore adopted to optimise both properties at the same time. The results show that it is possible to improve the ride comfort of the bus without affecting the handling properties considerably.