Universal Dependences of Frictional Interaction Parameters during Elastic Wheel–Road Contact

The questions of frictional interaction during the contact of a vehicle’s elastic wheel and a flat solid support surface under different loading conditions by force and moment are considered. The parameters of this interaction are investigated: the adhesion coefficient; its components by areas with static and sliding friction; static friction use coefficient; static friction proportionality coefficient; and relative coefficient of limiting realized static friction. Mathematical dependences in the form of smooth continuous functions are proposed for physically correct calculation of the specified parameters. Two options for loading an elastic wheel with a force and a moment are considered. It is shown that the adhesion coefficient for a given longitudinal wheel slip depends on the loading conditions: the lateral force along the wheel rotation axis and the moment in the rotation plane, as well as their sequence of occurrence. With the same values of force and moment, the adhesion coefficient can change at different sequences of their occurrence: up to 70% for high lateral forces (near to weight) and up to 12% for small lateral forces (up to 20% of weight). Three methods for calculating the adhesion coefficient in the contact of an elastic wheel with a flat solid support surface are proposed. When calculating the proposed characteristics of the methods, averaged zero diagrams were used in the absence of lateral wheel force for different elastic wheels and different types and conditions of road surfaces. To obtain them, the procedure of approximation of numerous experimental data of different researchers was carried out. The developed methods are valid for all elastic wheels and all types and conditions of solid supporting surfaces. The results of the work can be used with sufficient accuracy for practical calculations in the design modeling of the properties of stability, controllability, and braking dynamics of wheeled vehicles.