Modeling the parameters of free and driving wheel rolling modes taking into account the asymmetry of the normal reaction diagram

A method for determining the power and kinematic parameters of a tire and a wheel for free and driving modes of rolling is given. The displacement of the center of normal reactions of the road support surface was taken into account. The amount of displacement is presented as a linear function of the longitudinal force coefficient. The analytical description of the dependence reflects the relationship between the longitudinal force coefficient and the asymmetry coefficient of the diagram of normal reactions of the bearing surface and determines the displacement of the center of normal reactions towards the front edge of the contact area of the tire. The calculated asymmetry of the epure of relative normal reactions can be obtained by choosing the appropriate value of the asymmetry coefficient in the range from 1 to 0. Based on a numerical example, a graphical-analytical display of the force and kinematic parameters of rolling of a wheel with a 15.5-R38 model F-2A tractor tire is presented when using the epure of relative normal reactions described by a parabolic dependence of the fourth degree. The longitudinal force coefficient is determined taking into account the formation of the resulting longitudinal reaction by two components - in the slip section and in the rest section of the tire contact pad elements. It was found that the maximum value of the longitudinal force coefficient for an asymmetric epure of relative normal reactions is observed with a larger value of the wheel slip coefficient compared to a symmetric epure, but remains practically unchanged for both compared diagrams of relative normal reactions. The presented method for determining the power and kinematic parameters, taking into account the asymmetry of the epure of normal reactions of the supporting surface, can find practical application in the selection and substantiation of rational modes of operation of wheel propellers of tractor transport and technological units in various road conditions.

wheel, tire, rolling, force, mode, coefficient, slipping, friction, adhesion, epure