Research of Chassis Torsional Stiffness on Vehicle Handling Performence

Aiming at analysing influence of chassis torsional stiffness on handling performance, we build a four degrees of freedom vehicle model that includes chassis torsional degree to study chassis roll distortion. Influence of chassis torsional stiffness on steady-state roll angle of front/rear suspension and transient understeer gradient are simulated. Through changing chassis torsional stiffness, we find lateral acceleration and yaw rate are basically the same as original. Chassis torsional distortion has been diminished with the chassis stiffness increases. We propose sum ratios between chassis torsional stiffness and front/rear suspension rolling stiffness as rigid chassis evaluation index in Fomula 11. Suspension roll stiffness matching principle has been proposed for reducing the twist angle of chassis and it is certificated by five popular sedan´s K&C test result.