Frequency reduction and attenuation of the tire air cavity mode due to a porous lining

The tire air cavity mode is known to be a significant source of vehicle structure-borne road noise near 200 Hz. A porous lining placed on the inner surface of a tire is an effective countermeasure to attenuate that resonance. The two noticeable effects of such a lining are the sound pressure attenuation and the frequency reduction of the air cavity mode. In this paper, through both analytical and numerical methods, the mechanism of the effects of porous lining was studied. A two-dimensional duct-shaped analytical model and a tire-shaped numerical model were built to investigate the lined tire in conjunction with the Johnson-Champoux-Allard model describing the visco-inertial dissipative effects of the porous material. Design parameters of the porous lining were controlled to study their impact and optimal ranges of the design parameters were suggested. Finally, in experimental analysis, the sound attenuation and the frequency drop were observed in measurements of force, acceleration, and sound pressure. In conclusion, it was demonstrated that the suggested analytical and numerical models successfully predict the effect of porous lining and that the frequency reduction results from the decreased sound speed within the tire owing to the presence of the liner.