Influence of radial change of wheel dimensions on the automobile transverse stability

Abstract

One of the main characteristics of a car is the trajectory. Cars often have to move along the curvilinear trajectory, due to the fact that they need to turn from one path to another, bypass the obstacle, it constantly feels the effect of lateral forces that change or try to change the trajectory. When turning to the car, side forces and additional moments that increase longitudinal reactions, as well as the wheels' torque necessary for movement, are active. Estimated stability indicators are critical parameters of motion. There is no generally accepted system of estimating stability indicators, therefore, when considering physical processes, four main indicators are considered: the critical speed of motion by the curvilinear trajectory, which corresponds to the beginning of the transverse displacement of the means; critical velocity of the curvilinear trajectory corresponding to the beginning of the transverse slip of the vehicle; critical angle of inclination of the reference surface, corresponding to the beginning of the transfer of the means; the critical angle of the slope of the bearing surface, corresponding to the beginning of the transverse slip of the wheels. The boundary conditions of the movement of traditional and modified cars on which the radial change in the size of the wheels will be applied, which makes it possible to determine the values of the parameters of motion, in the course of which the loss of transverse stability, which leads to their rollover, is evaluated. The mathematical models, allowing to determine the values of critical speeds and radii of turns for traditional and modified cars are obtained. The mathematical models that allow to investigate the direct dependencies of the value of critical velocity on the radius of rotation and the inverse dependences of the permissible radii of rotation on the velocity value are constructed. These mathematical models are obtained for the study of the transverse stability of the rollover during the movement both on the horizontal and on the surfaces that have a slope to the center of rotation. On the basis of the obtained mathematical models, a computer simulation was performed which showed a significant advantage of modified cars in relation to traditional ones in terms of better preservation of transverse stability.