Determination of the mass center of a passenger car VAZ-21713

Abstract

Braking performance is one of the most important performance properties for any vehicle. When braking on a horizontal surface, a two-axle passenger car is subject to the force of gravity and counteracting vertical reactions at the points of contact of the wheels with the supporting surface, artificial resistance to movement, that is, braking forces, aerodynamic drag force, rolling resistance force, friction in wheel bearings, as well as force inertia counteracting the total resistance force. When braking on a slope, a longitudinal component from gravity is added to the listed forces. Under the influence of inertial force, a redistribution of vertical reactions occurs towards the front axle, which largely depends on the location of the vehicle’s center of mass. If passport data is available, the longitudinal coordinate of the center of mass is simply determined based on the distribution of the total and curb weight along the axes, however, for the VAZ-21713 passenger car with a station wagon body, such data was not available. Therefore, the authors decided to establish the weight ratio between the front and rear axles using an experimental and calculation method. The height of the center of mass was determined by a calculation method with elements of solid-state three-dimensional modeling based on the mass and dimensional characteristics of individual components and assemblies. In this case, the assumption was made that the center of gravity of each mass element of the vehicle is located at its geometric center. The obtained coordinates of the vehicle's center of mass allowed us to carry out a design calculation of the brake mechanisms and a verification calculation of the braking efficiency.