This presentation gives an outline of an empirical tyre model which describes vertical force reactions to road irregularities and wheel spindle displacements. Parameters for the model are derived from a series of simple laboratory tests. Both the empirical modelling technique and the experimental methods for parameter identification can be applied equally well to the description of longitudinal force response. In order to provide an accurate representation of tyre response, even in this low frequency range, it was necessary to include three elements in the model. Each of these elements describes a physical aspect of the tires reaction to road surface irregularities. Experimental results have shown that these are essentially independent and must therefore be described and derived separately. They are: (1) tyre, eigenfrequencies and stiffness/damping characteristics; and (2) a two part description of contact patch dynamics including: (a) a description of stiffness over contact surface; and (b) tyre/road contact geometry. The tire model has been found to provide a good description of tire response for frequencies up to 100 Hz for which it was designed. Calculation time remains acceptable allowing its inclusion in the handling simulation models for which it was intended. The improvement in accuracy over simple spring/damper representations is significant.
Abstract