Date of Award

12-2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Advisor

Thompson, Lonny L

Committee Member

Biggers , Sherrill B

Committee Member

Ziegert , John C

Abstract

Recently, Michelin has invented an innovative non-pneumatic tire which has potential for improved handling, grip, comfort, and less rolling resistance when compared to a traditional pneumatic tire. The non-pneumatic wheel is manufactured from a molding process with integrated shear ring and collapsible spokes designed to provide optimal uniform ground contact patch with low rolling resistance. The shear band is constructed from a polyurethane material with imbedded inextensible reinforcements. During high speed rolling in initial testing, the original prototype showed high noise levels at frequencies above 100 Hz. A possible source of noise could be due to vibration initiated from the collapsing and re-tensioning of the spokes during their transition and passage through the ground contact region. Other noise sources could be the interaction between the vibrating spokes and shear ring, and/or the contact interaction between the ring tread and ground. Previous work studied the effect of geometric parameters on spoke vibration and ground force interaction vibration amplitudes.
In the present work, a 2D planar finite element model with geometric nonlinearity and explicit time-stepping is used to simulate rolling of the non-pneumatic tire, and study the effect of spoke deviation from radial lines controlled by DeRad parameters defined at the hub and ring ends of spokes. Dynamic orthogonal arrays are used to evaluate their importance with other influential spoke parameters on reducing spoke and ground force vibration amplitudes. The current work also considers the design and analysis a new alternate spoke pair concept wherein every other pair has same thickness, curvature, or combinations of both. While evaluating the effects of the controllable geometric variables in the orthogonal arrays, combinations of uncontrollable factors of rolling speed and ground pushup are also considered.
The results indicate spoke length and curvature parameters are more influential than DeRad on vibrations of spokes and ground interaction. For equivalent mass, results for the alternating spoke pair design show that small changes (plus/minus 5%) in spoke thickness between pairs broadens the range and increases the number of frequencies of peak amplitudes for the ground reaction force, therefore reducing vibration amplitude compared to a reference model with uniform spoke pair distribution. Similarly, small changes in curvature in alternating spoke pairs reduce spoke vibration. Combining thin spokes with large curvature, and thick spokes with small curvature for alternating spoke pairs reduces both spoke vibration and vibration due to ground interaction.

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