ABSTRACT
The various techniques for evaluating the wheel numeric and vehicle performance
have been studied. The wheel numeric depends on many parameters; vehicle
weight, tire geometry, and soil strength in terms of cone index. The tire geometry
includes tire width, tire diameter, section height and tire deformation. The tire
deflection is very difficult to accurately measure. So the main purpose of this paper is
to develop a new wheel numeric formula with a new parameter depending on the
inflation pressure inside the tire instead of the tire deflection.
A theoretical study to investigate the effect of soil cone index, tire geometry and
vehicle weight on different wheel numeric has been carried out and so their effects
on the vehicle performance have been carried out. The performance of off road
vehicle on soft soil in terms of rolling resistance, drawbar pull and tractive efficiency
has been studied and investigated using variety of methods. These include;
theoretical, semi-empirical and empirical methods based on wheel mobility number.
The results showed that the new numeric formula gives a good correlation with
published results at different soil cone index, vehicle weight, tire width, tire diameter
and tire inflation pressure. Also the predicted performance has a good agreement
with published experimental results at same conditions.