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

Abstract

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 func-tion 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 parame-ters 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 longitu-dinal 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 ele-ments. 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 com-pared to a symmetric epure, but remains practically unchanged for both compared diagrams of rela-tive 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 applica-tion in the selection and substantiation of rational modes of operation of wheel propellers of tractor transport and technological units in various road conditions.