Analysis of Speed-Dependent Vibration Amplification in a Nonlinear Driveline System Using Hilbert Transform

The engine start-up process introduces speed-dependent transient vibration problems in ground vehicle drivelines as the torsional system passes through the critical speeds during the acceleration process. Accordingly, a numerical study is proposed to gain more insights about this transient vibration issue, and the focus is on nonlinear analysis. First, a new nonlinear model of a multi-staged clutch damper is developed and validated by a transient experiment. Second, a simplified nonlinear torsional oscillator model with the multi-staged clutch damper, representing the low frequency dynamics of a typical vehicle driveline, is developed. The flywheel velocity measured during the typical engine start-up process is utilized as an excitation. The envelope function of the speed-dependent response amplification is estimated via the Hilbert transform technique. Finally, the envelope function is effectively utilized to examine the effect of multi-staged clutch damper properties. CITATION: Li, L. and Singh, R., "Analysis of Speed-Dependent Vibration Amplification in a Nonlinear Driveline System Using Hilbert Transform," SAE Int. J. Passeng. Cars Mech. Syst. 6(2):2013, doi:10.4271/2013-01-1894. ____________________________________ line describe the direction-dependent hysteresis values based upon the stages. In particular, the hysteresis value H is assumed to be zero in the pre-damper stage between -φ1 and φ1, where the stiffness K1 is relatively low. The mathematical expressions of these two multi-staged nonlinear models are as follows: