THE TENSE-DEFORMED STATE OF VARIOUS DISC TYPES IN VEHICLE BRAKE DEVICES

The article is devoted to the tense-deformed state of solid and self-ventilated brake discs with cooling elements in the structure of vehicle brakes. The effect of energy loading of different disc types on the appearance and development of microcracks on their working surfaces is shown. The insufficient power consumption of brake discs on the cyclic braking mode of the vehicle affects the braking effectiveness of the working surfaces of discs due to the appearance of microcracks on them. The latter are the result of the influence of energy loading, and as a consequence, of high thermal stresses. The frictional interaction of the friction pairs "disk-overlays" contributes to the appearance of friction on the treadmill of grinding machines. The latter are a grid of arachnoid or separate arbitrary directed surface tears formed during the tread grinding of the disk friction, the material of which has high brittleness, hardness and reduced thermal conductivity. At the same time, the microcracks spread on the grain boundary in the surface layer of the disk metal. The plastic deformation causes a decrease in the density of the metal surface layer of the disc or an increase in its specific volume. The plastically deformed  during the electrothermechanical  friction layer cannot increase freely in the volume of the near-surface layer of the tread of the brake disc friction. At the same time, in the surface layer of the disk there are stresses of compression, and in the rest of its part we can observe the tensile stress. This argument assumes that the deformed surface layer is not even partially in a state of creep. Plastic deformation causes a decrease in the density of the metal of the surface layer of the disc an increase in its specific volume. Plastic deformation by electromechanical friction the layer cannot freely increase in volume. This is prevented by the non - deformed metal the surface layer of the friction path of the brake pulley. Depending on the temperature, the metal can be in an elastic and plastic creep state, the elastic force does not appear, and the deformation proceeds without the metal striving to restore the shape.