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The article presents the results of a study of the effect of the functional relationship between the parameters of the microgeometry of the brake disc surface and the level of the stress-strain state of the contact area on the thermal resistance coefficient. The results of an experimental study of the process of changing the step and altitude parameters of the microgeometry of the surface of the brake disc under the influence of normal and tangential forces realized during friction are obtained. It was found that under the influence of normal and tangential forces, the height parameters of the microgeometry tend to increase, and the step parameters tend to decrease. It is shown that when calculating the contact thermal resistance, it is necessary to take into account the functional relationship between the geometric parameters of the microroughness of the brake disc surface and the level of the stress-strain state of the contact area. The calculations performed without taking into account this connection lead to overestimated values of the contact thermal resistance and, accordingly, to errors in determining the values of heat fluxes passing through the contact area of the mating surfaces. The values of the constants, which depend on the design features of the friction unit of the disc brake and are used to determine the nature of the change in the geometric features of microroughnesses, have been specified. The correction of the input parameters of the microgeometry of the surface of the brake disc is performed, taking into account the dynamics of changes in their geometry under the influence of force loading. It is shown that it is advisable to take into account the dynamics of changes in the surface microgeometry in the analytical determination of the contact thermal resistance of a disc brake. The results obtained are recommended to be used in calculating the friction characteristics and assessing the heat fluxes passing through the area of mutual contact of the brake disc and brake pads of the disc brake.

Annotaion. The relevance of carrying out research works on improving the regulatory and methodological base in the development of promising railroad rolling stock structures with the use of new structural materials with nonlinear properties during deformation (physical nonlinearity) is substantiated in the work. The possibility of using the finite element method (FEM) procedure for creating such constructions is considered. Dependence of stresses on deformations is approximated by a cubic parabola. This made it possible to obtain generalizations of the well-known relations and algorithms of the classical theory of FEM with a nonlinear relationship between stresses and deformations. The proposed technique was tested in the evaluation of the stress-strain state (SSS) of an aluminum gondola car under various standard loads according to the 1st design mode. The effect of physical nonlinearity on the SSS of a spiral beam of a freight gondola car of aluminum alloy AMg6 was estimated. The calculation of the stresses generated by the action of a longitudinal force with eccentricity shows that the stresses in the nonlinear approximation are 13% lower than the corresponding stress values obtained by calculation in the linear theory. The results obtained can be recommended for the development of pilot projects of new structures optimized for weight and strength characteristics.

The article discusses the thermal state of the disc brake elements during braking, taking into account the distribution of heat fluxes between the friction elements. The results of the study of the influence of the thermal resistance of the medium filling the microcontact gaps, caused by reversible deformations of the surface microgeometry, on the thermal state of the disc brake elements are presented. Method - the description of the thermal state of the disc brake elements during braking is made on the basis of the Fourier - Kirchhoff differential equation of thermal conductivity, taking into account the influence of the thermal resistance of the medium filling the microgaps between the surfaces of the brake pad and the brake disc. Results of the work: The calculation of the thermal state of a railway disc brake was carried out taking into account the reversible deformations of the microgeometry of the surfaces of the working elements of the disc brake. The exact dimensions and shape of the disc brake elements are specified in the CAD system (SolidWorks). The graphs of changes in the thermal energy generated and dissipated by the disc brake at different initial speed and duration of braking are given. The obtained dependences illustrate the process of heat energy dissipation into the environment. The inertia of the friction system of the disc brake in relation to the dissipation of the generated thermal energy during braking is shown. It has been shown that the distribution of heat fluxes between the working elements of a disc brake depends on the level of reversible deformations of the microgeometry of the brake disc surface, which directly determine the thermal resistance of the medium filling the microcontact gaps. Taking this circumstance into account makes it possible to increase the reliability of calculations of the generated and dissipated energy by the working elements of the disc brake during braking. The results of the study are recommended for use in calculating the thermal state of the working elements of the disc brake during braking.

The paper proposes a method of measuring the transverse displacements of the rails. Made a priori error estimate. A version of the sensor and the concept of construction equipment.

The article presents theoretical studies of the interaction of the compacting machine with the soil of the road bed of the railway embankment. The results of the studies make it possible to establish the parameters of the sealant, which ensure an efficient flow of the compaction process of the ground environment. It is established that the rigidity of the working body of the roller must vary over a wide range. Experimental studies of a new sample of the working body confirmed the possibility of adjusting the rigidity in the required range for the effective use of vibrating rollers in the construction of railroad soil embankments.