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Tessa C. Russell


Mechanical and Aerospace Engineering


Much of the energy used by a solar car can be attributed to overcoming rolling resistance, and rolling resistance comes predominantly from the tires. The main goal of this project was to better understand the properties of the Bridgestone Ecopia tires used by the UMR Solar Car Team. Experiments were conducted to obtain this objective, measuring the vertical stiffness, lateral stiffness, and contact patch shape and area. As expected, with decreasing pressure and increasing load, the vertical and lateral deflections increased as well as the tire contact patch area. The stiffness parameters of the tire measured experimentally were used in an existing rolling resistance model for tires to measure quantitatively how load, pressure and tire misalignment affects the rolling resistance coefficient (Crr) for the tires. With increasing values of the misalignment angle, the coefficient of rolling resistance increased. It was found that a tire can have a larger misalignment angle at higher loads and higher pressures. It was found that load and pressure had the same effect on the coefficient of rolling resistance. The main conclusion that can be reached from the Crr, results is that the tires should not have a misalignment angle greater than I degree to keep the Crr down.

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