Force Transmission Characteristics for a Loaded Structural-Acoustic Tire Model

Concerns about tire noise radiation arise partly from city traffic planning, environmental protection, and pedestrian safety standpoints, while from the vehicle passengers' perspective, noise transmitted to the vehicle interior is more important. It is the latter concern that is addressed in this article. Sound-absorbing materials generally offer good absorption at higher frequencies, but the reduction of relatively low frequency, structure-borne tire noise is a continuing focus of many auto manufacturers. A tire's internal, acoustic cavity resonance is a very strong contributing factor to tire-related structure-borne noise, and it can easily be perceived by passengers. Some reduction of vehicle cabin noise can be achieved through the insertion of sound-absorbing material in the tires. However, apart from the additional cost for such tires, there is also an increased complexity when repairing them because of the need to avoid damaging the sound-absorptive lining. In that light, modifying the design of the tire-rim and suspension system to decrease the cavity noise influence without the addition of sound-absorbing material has a clear benefit. To that end, a fully coupled, structural-acoustic finite element tire model with rigid ground contact is described here. The model was established in the Abaqus/CAE 6.13-4 environment and was driven by a point force excitation at the leading edge of the contact patch. Tire surface velocities and hub center accelerations were calculated in order to study how the internal air cavity affects the force transmissibility characteristics of a tire structure. Simulation results have indicated that a match of the vertical cavity mode with an odd, circumferential flexural mode of the treadband can significantly increase the vibration levels transmitted from the tire to the rim center, and thence the hub and vehicle's suspension. Thus it is suggested that changing the treadband stiffness to avoid such a match can significantly reduce the impact of the cavity resonance.