Dynamical tyre forces response to road unevennesses

The contribution deals with the quantitative prediction of tyre forces and moments due to short-waved road unevennesses, as far as they influence vehicle dynamics. Safety loss frequently is supposed to be closely correlated to the RMS value of dynamical wheel load changes. But this doesn't take into account the frequency dependency of the amount of loss in lateral and longitudinal forces caused by wheel load fluctuations. In order to investigate this effects mentioned, extensive simulations with the semi physical tyre model BRIT (Brush and Ring Tire Model) have been performed and a variety of frequency responses is presented and discussed. Thereby the input consists of a sine shaped road surface with varying wave lengths. Before, some modifications of BRIT, done especially for this investigations, are described in detail and the effects of these improvements on the simulation results are presented.