Modelling of Dynamic Contact - Exemplified on the Tyre/Road Interaction

Doctoral thesis, 2002

Noise is a severe problem in modern society. Road traffic noise is a substantial contributor and the tyre/road interaction is the main noise source for normal driving conditions. Despite more than 30 years of research, there is a lack of quantitative tyre/road noise prediction models. The work presented in this thesis extends an existing model for tyre/road noise. Of special interest is the contact between the tyre and road that to a great extent determines the quality of the acoustic rolling model. A key point is the so called influence coefficients of the tyre tread, which describes how adjacent points in the contact interact. A tyre model based on the elastic field equations is proposed, which at the moment is the only tyre model for calculating influence functions at the tread. The tyre model predicts both radial and tangential impulse response functions including local deformation and hence, the influence coefficients. Furthermore, a contact model is presented, which uses the influence coefficients to calculate the contact forces. This model is in addition extended to take into account roughness variation over the tyre width. The proposed contact model results in a simpler model for the sound radiation, since no additional formulation of the local deformation is needed. Contact forces, tyre vibrations and sound radiation are compared to existing models. The results agree well with those of previous models for soft tyre treads and for rough roads. In other cases, the proposed model shows more realistic results. However, further validations to measurements are needed.