Experimental Measurement of On-Vehicle Rolling Tire Contact Patch Shear Energy Intensity at Various Slip Angles
1 online resource (57 pages) : PDF
University of North Carolina at Charlotte
It has long been accepted that tire wear is directly related to the energy generated due to shear at the contact patch. Tire wear at any given point on the contact patch is proportional to the amount of shear energy intensity acting at that point. In this research, shear energy intensity as a product of sliding displacements and frictional force at a sufficient number of points is mapped across the tire contact patch.The phenomenon of Frustrated Total Internal Reflection (FTIR)  is used to measure the normal stress distribution across the contact patch. The normal stress is calculated based on the amount of light intensity acting at each pixel across the contact patch. The tread blocks on the tire are painted with white dots, and a similar method without the dimpled plastic of the FTIR is used to obtain the point by point tread block displacements. With the help of computer image processing, shear energy intensity as a function of frictional force and tread block displacements are mapped at multiple time stamps across the contact patch at various slip angles. Results show that the total shear energy acting across the contact patch increase with increasing slip angles. This demonstrates that the tire is going to wear more aggressively as the slip angle increases. The shear energy intensity mapped across the contact patch show that the tire is going to experience more irregular wear as the slip angle increases. From the results, it is seen that the shear energy intensity is more uniformly spread out at very low slip angles and at higher slip angles, the shear energy intensity is almost zero at the leading edge of the contact patch and maximum at the trailing edge of the contact patch. This corroborates the premise that highest shear is at the trailing edge of the contact patch.
SHEAR ENERGY INTENSITYTIRE FOOTPRINTTIRE WEAR
Keanini, RussellBari, Saiful
Thesis (M.S.)--University of North Carolina at Charlotte, 2017.
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