Passive Control of Tire Vibration
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Passive Control of Tire Vibration with a Dry Polymer Additive:
Advances in vehicle design over the last twenty years have been accompanied by reductions in the weight of automotive chassis and suspensions. The resulting increase in vibration transmission has led to more complaints about ride harshness and vibration.
At the same time, advancements in the tire industry have significantly increased the accuracy and repeatability of tire manufacture, reducing the amount of tire/wheel imbalance. This has decreased the importance of vibrations induced by tire/wheel imbalance relative to vibrations induced by other sources such as uneven road surfaces and radial force variation.
Historically, lead weight balancing has been the primary means for reducing tire vibrations. Discrete masses are added to the inside and outside rim to balance the offset mass and locate the wheel/tire center of gravity at the center of the axle. However, lead weight balancing does not account for sources of vibration other than mass imbalance. Radial force variation is caused in part by mass imbalance, but also by a host of other factors: tread pattern, radial ply overlap, material stiffness inconsistency, component placement, etc.
In this study, we experimentally investigate the effectiveness of a powder additive in reducing vibrations caused by mass imbalance and other factors. The particle additive used in this study is EQUAL Automotive Formula, a dry polymer particle product designed to reduce the vibration level of a loaded pneumatic tire in the dynamic mode. The quantity of particles is placed inside the tire chamber, and becomes distributed around the inner circumference of the tire as it rotates.
A series of highway and laboratory experiments were performed to assess the performance of the additive product. The laboratory dynamometer tests showed that it reduced the vertical vibration magnitude at the fundamental frequency (one per tire revolution). The average reduction compared to dual plane balanced wheel assemblies was 29% in on-vehicle acceleration dynamometer testing, and 55% in fixed axle dynamometer testing.
Highway experiments showed that both tire-induced and periodic road-induced vibrations were consistently reduced. Videos created of the particles moving dynamically within a rotating tire aided in understanding the mechanism by which tire vibration is reduced.