An in-plane flexible ring model for the analysis of the free and forced response of a rolling tyre

The increased demand for vibroacoustic comfort as well as regulations on noise and vibration levels have made the NVH (Noise, Vibration, Harshness) performances of a vehicle to become one of the fundamental design criteria. Therefore, predictive models for the analysis of noise and vibration transmission mechanisms represent interesting tools to support the R&D department of the automotive companies. Focusing the attention on passenger's comfort, the vibrations induced by the tyre/road interaction propagate from the contact area to the hub and finally inside the cockpit through structure-borne transmission paths. This can be regarded as one of the major contributors to the car cabin interior noise at low frequencies (between 20 and 500 Hz). Simplified models able to interpret the waves propagating inside the tyre structure and influenced by the angular speed may support the studies in this research field. To this end, an analytical model based on the theory of the flexible ring on elastic foundation has been developed. It allows analysing the tyre dynamics in both static and rolling conditions. Model parameters have been calibrated based on an Experimental Modal Analysis of the static tyre. The free response of the tyre shows the bifurcation effect at different rolling speeds, while a cleat test simulation has been carried out to investigate the forced response of the tyre.