FINITE ELEMENT STUDY OF ACOUSTIC MODE FORCE TRANSMISSION IN A LOADED, STRUCTURAL-ACOUSTICAL TIRE MODEL

摘要

Concerns about tire radiation noise arise from traffic planning, environmental and pedestrian safety standpoints, while from the vehicle passengers' perspective, noise transmitted to the vehicle interior is more important: the latter concern is addressed in this paper. Tire vibration propagates through the vehicle suspension and causes objectionable interior noise; such noise is usually defined as structure-borne noise. Sound absorbing materials have good absorption properties at higher frequencies and are effective at eliminating airborne tire noise, which usually dominates above 500 Hz. Thus, the reduction of relatively low frequency structure-borne tire noise is a continuing focus of auto manufacturers. Among all the structure-borne tire noise sources, the tire internal cavity resonance is a very strong contributing factor, normally near 200 Hz for current tires, especially since this resonance can be easily perceived by passengers. Reduction of this mode can be achieved by inserting sound absorbing material within the tires. However, beyond the cost of such tires, there are durability concerns and it is difficult to repair such tires without damaging their sound absorptive properties. Thus, an improved design of the tire-rim and suspension system to decrease the structure-borne cavity noise still has many benefits. In that context, a fully-coupled structural-acoustic finite element tire model with ground contact is described here. The model was established in the Abaqus/CAE 6.13-4 environment, and was driven by forces near the contact patch. The tire surface velocities and hub center accelerations were calculated in order to study how the internal air cavity would affect the force transmissibility character of the tire structure and how the input force would influence the response of the tire system. It has been found that there can be strong coupling between circumferentially asymmetric treadband modes and the verified acoustic cavity mode which amplifies the structure-borne transmission, and which should thus be avoided.