Title page for ETD etd-07132009-163511


Type of Document Master's Thesis
Author Taylor, Benjamin Paul
URN etd-07132009-163511
Title Experimental Evaluation and Semi- Empirical Modeling of the Tractive Performance of Rigid and Flexible Wheels on Lunar Soil Simulant
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Sandu, Corina Committee Chair
Ahmadian, Mehdi Committee Member
Taheri, Saied Committee Member
Keywords
  • wheel mobility
  • off-road testing
  • Lunar soil simulant
Date of Defense 2009-07-09
Availability unrestricted
Abstract
Understanding the effects of various wheel parameters on tractive performance is not completely understood. In order to properly quantify the individual effects of wheel parameters on the mobility of rigid and flexible wheels in soft soil, tests were performed, in cooperation with NASA Glenn Research Center (NASA-GRC), using the terramechanics rig at the Virginia Tech Advanced Vehicle Dynamics Lab (AVDL). To conduct such a study, four different wheels were evaluated under similar normal loads, slip ratios, and soil density. The first wheel represents the baseline, against which all the others were benchmarked. The remaining three wheels included the following parameter changes: 1) same diameter as the baseline but wider, 2) same width as the baseline but smaller in diameter, and 3) same width and diameter as the baseline but with a longer contact length. For each test the normal load, drawbar pull, and driving torque were measured and recorded for further analysis. To measure the effect of the changes in the wheels’ parameters on the contact patch under different loads, a pressure pad was embedded below the surface of the Lunar simulant to measure the contact patch shape, size, and pressure distribution. Analysis of the experimental results showed that the drawbar pull was more significantly affected by the wheel diameter than by the contact width, and that same trend followed suit for the driving torque. Overall, the greater contact patch area resulted in a higher drawbar pull and torque.
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