Tyre-road interaction noise

Tyre noise is generated from vibrations caused by the impact and release of tread blocks entering and leaving the contact patch. These acoustics sources are then differentially amplified by the tyre/road geometry, resulting in far-field noise. The amplification is strongest in the 'horn' between the tyre belt and road surface, so that contributions from local vibrations in this region dominate the far field. This makes the problem intractable to fully numerical (FEM/BEM) approaches. Instead, we adopt a simplified strategy, whereby the tread vibrations are estimated from a flat plate model. The amplification of the sound they produce is then determined from an acoustic BEM computation. In this paper, we present the vibration model and initial far-field sound predictions; the horn effect calculation is described in Graf et al. The tyre structure around the contact patch is represented by an infinite, flat elastic plate, to which the tread blocks are attached. The forces and displacements at the block faces can be found by expressing the displacements in terms of the system impulse response and the block forces, and applying known values of force/displacement as boundary conditions. This approach has been implemented for strictly normal forces and displacements; however, its extension to the general case is straightforward. The vibration model is validated by comparison with experimental transfer functions between block pairs and with measured tread block accelerations on a rolling road. Far-field noise predictions and data are then used to assess the extent of the normal displacement contribution. Lastly, future developments of the model are discussed. (A) For the covering abstract see ITRD E113232.