WHEEL ROLLING RADIUS WITH ELASTIC TIRE

The rolling radius of the wheel is considered as a result of normal and circumferential deformations of its pneumatic tire, caused respectively by the normal load and the torque applied to the wheel. Consideration of the normal deflection of the tire enabled the value of the rolling radius of the driven wheel to be represented as a function of the axial load per wheel and the radial rigidity of the tire. To assess the adequacy of the developed model, the example of the 26°-2° tire used in trucks is used to calculate the kinematic radius for different values of the normal load. Analysis of the calculation results shows that the kinematic radius of the driven wheel decreases linearly with increasing normal load. This is in good agreement with the results of previous experimental studies. When considering the action of torque, it is considered that it causes a tangential (circumferential) deformation of the tire, i.e. its twisting, as a result of which the rim of the wheel makes a certain turn relative to its periphery. In this case, this rotation of the rim is not accompanied by a longitudinal displacement of the axis of rotation of the wheel itself. Since the torque breaks the single-valued relationship between the linear and angular velocity of the wheel, this is reflected in the kinematic radius of the wheel. Based on the dependence of the twist angle and torque, an analytical dependence of the rolling radius on the algebraic magnitude of the torque and the torsional rigidity of the tire is established. Calculation of the rolling radius of the wheel, carried out according to this formula, shows that when the torque is applied, a linear decrease in the rolling radius occurs, and when the braking torque is applied, on the contrary, its linear increase is shown. Such a change in the rolling radius completely agrees with the results of experimental studies of various types of pneumatic tires.

wheel rolling, kinematic radius, free radius, dynamic radius, normal stiffness of tire