Experimental study on the contact patch pressure and sinkage of a lightweight vehicle on sand

This study focuses on improving the understanding of the mobility of lightweight wheeled vehicles on sand by testing the significance of payload, ground speed, sand gradation/grain size, and sand moisture content on contact patch pressure and tire sinkage. Extensive testing of a lightweight wheeled all-terrain vehicle (ATV) was structured in two experiments. Tire sinkage was measured at the width-wise center of the imprint of both the tread and the carcass. Pressure distribution in the contact patch was recorded using an embedded pressure pad, from which the average and peak (and difference) pressures were found. In the first experiment, measurements were taken each time the ATV was driven over combinations of four plots of groomed sand, two moisture contents, three payloads, and three speeds. Average pressure was highly affected (95+% confidence) by sand grade, vehicle speed, and payload and the interactions of sand grade-speed, and sand grade-moisture content-vehicle speed, and borderline affected (90-94.9% confidence) by the moisture content-speed interaction. In the second experiment, the ATV was driven over each plot of dry sand one hundred consecutive times at one speed-payload combination without grooming between runs, showing the cumulative effect of multiple passes over each sand pit on each measure of mobility.