Effects of road roughness, aerodynamics, and weather conditions on automotive wheel force

Abstract

Taking road roughness, aerodynamics, and weather conditions, viz temperature and humidity, into consideration, the force applied to the wheel of a half-vehicle model traveling at constant speed has been calculated. A D-type rough horizontal road according to ISO 8606 evaluations was chosen for the experiment and the surface profile of which was measured by means of a topographic camera of Leica series to acquire discrete data to model the road roughness. The data have been converted from discrete points into smooth continuous linear functions with quadratic blends, because of the fact that the governing differential equations of motion of the vehicle model require the road roughness and the time rate of change of them. The line of action of wind or aero-dynamical force applied to vehicle model has been assumed to pass through the vehicle mass center. The vibrations of the half-vehicle model have been found via the Runge-Kutta method. Design of Experiments (DoE) has been used to investigate the effects of air temperature and humidity on the front and rear wheels. It was found that the value of force applied to the front wheel is far greater than that applied to the rear wheel (about 16.5%). Also, the role of the air temperature is much more effective on the wheel force than the air humidity. Moreover, the force of the front wheel is directly related to the values of weather parameters and the force of the rear wheel is inversely related to it.