Dynamic and acoustic characterisation of automotive wheels

The subject of this paper is the dynamic and acoustic characterisation of an automotive wheel. In particular, an experimental research activity previously performed by the authors about the dynamic behaviour of automotive wheels has been extended to the acoustic field. This experimental research has begun in the laboratory of the Mechanics Department of Politecnico di Torino where the modal analysis of the SAAB 640/6Jx15H2 wheel has been carried on step by step, starting from the rim in the most simple constraint condition to realise in laboratory, that is the free-free condition, up to the wheel (rim with tire) clamped to a real automotive hub; two cases have been considered: the wheel in hanging condition, that is with the vehicle on a lift-bridge, and the wheel laying on the ground. Then an acoustic study, analytical, numerical and experimental, of the cavity tire has also been performed. The experimental analysis has been carried on by introducing a microphone in the tire cavity (with no pressure) and by measuring the corresponding response level. The analytical study has been performed by utilising analytical relationships known in literature and a model of the tire cavity with an equivalent geometry. The numerical analysis has been carried on by means of a Boundary Element Method (BEM) model of the cavity. All obtained results, both dynamic and acoustic, have been analysed and compared to those concerning the experimental tests of the wheel clamped to the vehicle hub.