Passenger Car Stability Under Random Wind Excitation

The directional stability properties of passenger cars under high speed, straight running conditions form a major contributory factor in overall subjective ratings of vehicle handling, comfort and driveability. The aim of the paper is to investigate the links between straight running properties under random wind loading and vehicle design parameters.

A linear, three degree of freedom vehicle model was selected, to which a simple driver model could be incorporated as necessary. The wind loading excitation was modeled using a quasi-static approach, involving a randomly varying side wind with statistical properties taken from existing literature. The response properties of the vehicle with and without driver were characterized by performance indices such as root mean square values of vehicle motions. Finally, these results were analyzed to search for correlation between the performance indices and vehicle chassis design features such as tires, steering system and suspension kinematics.