Kim J., Park S., Lee J., Kang S., Kang J.

In most researches on ride comfort analysis of passenger vehicles, the flexibility of the vehicle body has not been considered as an important factor because the resonance frequencies of the vehicle body related to pitching, yawing, and rolling motions are approximately below 10 Hz while the resonance frequencies of the vehicle body related to the flexibility are approximately above 20 Hz. However, in this paper, we found that modification of the local flexibility (or local stiffness) of the 4 parts on which shock absorbers are mounted in the vehicle body has some influence the level of ride comfort. A one-dimensional, theoretical model is devised to qualitatively examine the effect of the change in the local stiffness of the vehicle body on the ride comfort. Based on the results obtained from the analysis of the one-dimensional model, multi-body dynamic analysis considering the flexibility of the vehicle body is performed using MSC/ADAMS and MSC/NASTRAN. More concretely speaking, natural frequencies and mode shapes computed by MSC/NASTRAN are used as input data for multi-body dynamic analysis in MSC/ADAMS. It is confirmed that the ride comfort can be improved by appropriately changing the local stiffness of the vehicle body through several simulations using MSC/ADAMS. The simulation results agree well with the experiment results.