Structure-borne road noise is an important factor affecting passengers’ overall riding experience. It is well-known that the fundamental acoustic resonance of the tire cavity can generate net forces on the rim, usually in the vicinity of 200 Hz. This effect can be reduced by placing sound absorbing material within the tire cavity. However, modifying the design of the tire and suspension system to decrease the cavity noise influence without the need for adding sound absorbing material would clearly be beneficial in terms of decreased cost and complexity. Previous finite element simulations have shown that tires in which even treadband circumferential flexural modes align in frequency with the vertical cavity acoustic mode exhibit relatively low cavity-related vibration levels. In contrast, when odd circumferential treadband modes align in frequency with the vertical cavity mode, cavity-related vibration levels are relatively high. This behavior follows from the fact that the contact patch imposes a zero radial velocity condition on the treadband, and when an odd mode is driven on the remainder of the treadband, one maximum in the modal distribution appears at the top of the tire, which then matches the vertical cavity mode shape and creates a net force on the rim. Here, the simulation findings were verified based on experimental measurement of hub vibration and tire dispersion relations.
Tire Noise, Acoustic Mode, Finite element model, Structure-borne vibration
Acoustics and Noise Control
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