Kindt P., De Coninck F., Sas P., Desmet W.

Tire vibration modes as a characterization of tire dynamics are used in a broad range of tire/vehicle system simulations, ranging from low-frequency vehicle handling to higher frequency structure-borne and air-borne noise simulations. The modal parameters are used either to define a complete modal tire model or to calibrate internal parameters of a tire model in order to obtain the proper dynamic behaviour. This paper presents the experimental modal analysis of a non-rotating radial tire under different boundary conditions. A first part presents the experimental modal analysis of a slick tire - tire without tread pattern - and a commercial tire, both of tire size 205/55R16. The tire is excited with 2 shakers and the response is measured in 378 points spread over the tire and rim. The responses are measured in radial, tangential and axial direction by tri-axial accelerometers. The modal analysis is performed under different boundary conditions: free tire, unloaded tire on a fixed hub and loaded tire on a vehicle hub. Mode shapes, resonance frequencies and modal damping are assessed up to 350 Hz. Throughout the whole modal analysis, practical testing considerations and limitations in accuracy and frequency range are discussed. This knowledge is important because it determines the accuracy and performance of tire/vehicle system simulations which use the experimental modal tire parameters as input data. The second part of the paper analyses the influence of the different boundary conditions on the modal parameters of the tire. The dynamics of both the rim and the enclosed air cavity of the tire are also considered. This global analysis will contribute to a better physical understanding of tire vibration modes. Finally a scope is given on future NVH tire research and testing at the KULeuven Noise and Vibration Laboratory.