Rolling resistance of an elastic wheel during rectilinear movement on an undeformed surface

Abstract

The paper presents the results of studying the rolling resistance coefficient of the elastic wheel during rectilinear movement on an undeformed bearing surface. Considering the elastic wheel as a complex integral mechanism, the forces and moments acting on the wheel during overcoming the rolling resistance are analyzed for two cases: the driven wheel and the driving wheel. It is established that the rolling resistance of the driven elastic wheel is overcome by an active pushing force applied to the wheel axis from the vehicle body and directed along the wheel motion vector. It is balanced by the reaction of the bearing surface, which is equal in magnitude and opposite in direction. The reaction of the bearing surface and the pushing force creates a moment relative to the wheel axis which is equal in absolute value to the rolling resistance torque. Rolling of the driving wheel is ensured by the torque applied from the vehicle transmission to the wheel hard disk which causes an active force in tire contact with the bearing surface, directed in the opposite direction to the wheel speed vector. This active force is counterbalanced by a pushing force applied to the wheel rotation axis and directed in the direction of the wheel motion vector. The rolling resistance of an elastic wheel during rectilinear motion is determined by the rolling resistance coefficient, which is the ratio of the displacement of the equivalent normal reaction to the wheel's dynamic radius during its motion. It is stated that with increasing speed and decreasing air pressure in the tire, the rolling resistance coefficient increases, and the magnitude of this increase depends on the elastic and damping properties of the tire and can currently be determined for specific tires only experimentally.

The results of the research can be useful for experts working to improve the fuel efficiency and mileage of car tires.

Key words: elastic wheel, rolling resistance coefficient, undeformed surface, rectilinear movement, speed, air pressure in the tire.