ON THE LOW-FREQUENCY INPLANE FORCED VIBRATIONS OF PNEUMATIC TYRE WHEEL/SUSPENSION ASSEMBLIES/

The paper contains an interim report on a research project into the lo ngitudinal vibrations of vehicles. The aim is to improve understanding of the process by which tyres come to vibrate by rolling along surfac es which may be smooth or profiled and the transmission of the vibrati on into the vehicle cabin. A description of a specially designed rig i s given. This allows control of the boundary conditions of a tyre / wh eel assembly which runs on a rotating drum and allows forcing to be ap plied by an electromagnetic shaker to the hub in the vertical or longi tudinal direction. A measurement scheme has been implemented to record forces and translational and spin accelerations of the hub. A mathema tical model of the rig has been built using the multibody modelling so ftware Autosim The tyre is represented as a hub and rigid circular rin g with translational and rotational freedoms between them. The hub is mounted in a suspension system allowing it translational and spin free doms. The model and the measurements are used to generate frequency re sponses, and a parameter identification scheme is being followed to ob tain a best fit of the theoretical results to the experimental results in the frequency range up to about 100 Hz. Vibration spectra and comp arative experimental and theoretical frequency response functions are included.