Abstract
A vehicle model was developed for the investigation of the influence of ride motions on handling dynamics of passenger vehicles using ADAMS. Among Several tire models, SWIFT tire dynamics model is selected for this analysis due to its capability of proper simulation of vehicle handling on rough road. Then the dynamic behavior of this model is investigated on test rig using vertical force and slip angle fluctuations that are simulated in ADAMS.
The inputs of the vehicle model are the steering wheel angle and a road profile at each side of vehicle. The lateral acceleration versus steering wheel and sideslip angles in a smooth road for magic formula and swift tire models is compared with each other, and good agreement was shown to exist.
In this paper the combined motion of the vehicle was investigated by applying several step steering wheel angles as input for two models of tire (magic formula and swift models) while traveling on a rough road surface. It was shown that the cornering ability at low and moderate levels of lateral acceleration on the roads with moderate roughness was similar to the results on a smooth road, but larger body side-slip and tire slip angles would be occurred over the rough road surfaces with similar steering inputs. The maximum achievable lateral acceleration was reduced on roads with moderate roughness owing to the earlier saturation of tire slip angles compared with those on smooth roads. Over very rough roads and at high lateral accelerations, because of the large fluctuations of normal loads and the rapid drop in available lateral force, the body side-slip angle dramatically increased, which led to instability characterized by the oversteering behavior.
Keywords: handling, tire dynamics, road roughness, modelling, simulation