Abstract: In order to effectively solve the problem of over-estimation of the existing formulae for calculating the root mean square (RMS) of vehicle vibration responses in practical engineering applications, the filtered white noise road spectrum is used as the road input model of vehicle system, and by using the random vibration theory and the integral solving method of complex variable function and based on quarter vehicle model, the RMS calculation formulae for the car body vertical vibration acceleration, the suspension dynamic deflection, and the wheel dynamic load are derived and verified by real vehicle test. The comparative analysis with the calculation results of traditional white-noise road spectrum input model indicates that the calculation formulae derived can more truly reflect the actual vibration of vehicle, while the traditional calculation model overestimates the vehicle vibration responses under high-speed operation. The formulae can be effectively applied to the estimation of vehicle driving vibration responses, the prediction of road grade, and the estimation of suspension damping ratio in vehicle initial design.

Key words: vehicle vibration responses, filtered white noise, root mean square value, calculation formulae, overe-stimation