The effects of the aerodynamic actions on the body of automobiles running at high speed on randomly profiled roads are studied. The forces acting on the body are introduced as functions of the air speed and some of the state variables describing the vibrations in the vertical plane of the vehicle. The linearised analytical expressions of these forces assume a very interesting form: Sky-hook springs and sky-hook dampers can be used to model the aerodynamic forces acting in the vertical plane of the vehicle body. Numerical simulations and experimental tests have been carried out to investigate the effects of aerodynamic forces on the ride comfort and road holding of an automobile running at high speed on a randomly automobile running at high speed on a randomly profiled road. Both theoretical and measured data state that these effects appear to be sensible starting from vehicle speed of 40-50 m/s. Suspension parameters should be tuned to account for aerodynamic effects which become more and more effective as the vehicle speed increases. Considerable improvement of ride comfort could be gained from a proper combined design of the suspension system and body shape. (A)
Samenvatting