The existing method for predicting the tractive performance of off-road vehicles is based on the measurements of terrain parameters made under static conditions, and neglects any dynamic effects on vehicle-terrain interaction. It has been shown, however, that in off-road locomotion the unevenness of terrain surface often produces considerable vehicle vibration and dynamic load on vehicle running gear. In order to improve the prediction of vehicle performance, it is of importance to investigate the effect of vibration on vehicle-terrain interaction.
This paper first describes an experimental study on the effect of vertical vibration on shearing characteristics between vehicle running gear and terrain under simulated operating conditions. It is found that the amplitude of dynamic load and slip velocity have a profound effect on the horizontal shearing force developed on vehicular ground contact areas. In general, the higher the amplitude of dynamic load and the lower the slip velocity, the less the horizontal shearing force will be developed.
The second part of the paper is devoted to the examination of the relationship between vehicle vibration and surface irregularity. By integrating the results of the study on vehicle vibration excited by surface roughness with the experimental results concerning the effect of vibration on vehicle-terrain interaction, a general framework correlating vehicle vibration and vehicle performance with terrain conditions is established.
It is hoped that this study will provide guiding principles for more rational prediction and evaluation of off-road vehicle performance.