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Experimental investigation of vehicle mobility using a novel wheel mobility number

Shawky Hegazy, Corina Sandu
Journal of Terramechanics, Volume 50, Issues 5–6, October–December 2013, Pages 303-310, ISSN 0022-4898,
Abstract: The wheel mobility number is a dimensionless variable used to predict the combined effect of tire and soil parameters on tractive performance. As the mobility number increases, the tractive performance improves. The wheel mobility number depends on soil strength, tire load, and tire geometry (width, diameter, section height, and deflection). The main purpose of this paper is to investigate the effect of tire and soil parameters on vehicle mobility. For this purpose, the soil strength is obtained experimentally using an electronic cone penetrometer. The tire geometry is obtained by experimental testing at different loads, from 2 to 6 kN. This includes the effect of the variation of tire inflation pressure from 100 to 250 kPa on tire section height and tire width. The tire inflation pressure, tire width, and wheel diameter are used as independent variables to investigate the relative wheel numeric. The effect of the soil strength, tire load, and tire geometry, as dependent variables, on the wheel mobility number, is also investigated. The results show that the mobility number increases when soil strength and tire diameter increase, and tire width, tire load, and tire pressure decrease. Based on theoretical analysis and experimental testing, a proposed wheel mobility number is introduced. It depends on the wheel numeric and the square root of the difference between the tire section height and the tire deflection, divided by the tire diameter. Using the proposed wheel mobility number, the vehicle mobility is predicted and a very good correlation with experimental data is obtained.
Keywords: Mobility number; Soil strength; Tire pressure; Tire geometry; Vehicle performance