Igor Nikolaevich Kravchenko

This paper is devoted to simulation results obtained for crack condition observed in the course of a selective fracture of copper slag particles intended for using under abrasive waterjet cutting. The simulation has been performed based on the concept of a nonlocal model of elastic materials, which assumes a compensation for high stresses at sharpened tips by a nonlocal interaction beween the crack faces in this area owing to surface molecular forces. The simulation results make it possible to provide selective (targeted) and controlled separation of components composing copper slag particles under crushing into separate components for to apply them to the abrasive waterjet cutting.

The article attempts to extend the methodology of mathematical modeling of critical phenomena as nonequilibrium phase transitions occurring at the initial stages in the spinodal decomposition mode to the process of destruction of structural materials. The method of thermodynamic analysis of critical phenomena is considered using the example of constructing a mathematical model of transformation from elastic deformation to creep. A mathematical description is given of elastic deformation, plastic flow, and irreversible transition of one into another in a single-phase model, without isolating the transformed state as an independent phase; formation of a creep zone in the terminology of Barenblatt.

The article proposes a new method for modifying the surface of polymers, in particular, a method for increasing the roughness of polyurethane-based materials through their chemical treatment without preliminary and subsequent operations of other types of treatment, ensuring increased adhesion between the modified polyurethane surface and the applied adhesive.

A digital photogrammetry method for assessing wear on deep ripper working parts has been developed. This method involves digitally photographing worn parts, then scaling the images in a CAD environment and mathematical and statistical data processing. Results of wear measurements in subsoiler chisel cross-sections are presented. It was found that wear on the chisel nose is uneven, with the highest average value in the working section’ central zone (57.4 mm). The study’ practical significance lies in the potential application of this method in technical service companies to simplify and improve diagnostic accuracy, as well as in the design of more wear-resistant structures for the working parts of soil-cultivating machines.

Methods of soil inversion by disc ploughs are analyzed, with particular attention to spherical discs. It is shown that a soil clod undergoes rotational mot

The article pays special attention to the issues of strength of materials, resistance to destruction, and reliability of their functioning under special operating conditions. The mechanical properties during the production of blanks, fatigue, and dynamic loading, as well as wear resistance as a relationship between the properties of materials and strengthening technologies, are studied. The problems of fracture mechanics and issues of resource assessment of industrial materials are considered.

A contact elasticity problem on motion of a cylindrical stamp over an elastic half-plane surface is solved with allowance for abrasive wear. A mathematical model is proposed, which includes an equilibrium condition and an integral equation for the contact pressure distribution. Dimensionless parameters are introduced to simplify the description of the process. The solution is based on the expansion of functions in Chebyshev polynomials and truncated series. Approximate analytical expressions for the stamp pressure and upset are obtained. It is shown that the pressure distribution evens out over time and the upset approaches a linear time dependence. The results of the calculation are compared with the boundary conditions of the problem and the process dynamics is analyzed. The obtained dependences can be used in engineering assessments of component wear and in calculating the durability of structural elements under the contact interaction.

In the mathematical modeling of the crystallization process, the results of a numerical experiment were used, in which a banded structure of the initial stage of the process was discovered, the mechanism of which is diffusion stratification. Qualitatively, this is consistent with the natural experiment. In the terminology of G.I. Barenblatt, the process is related to flow of the transformed state in the initial stage of crystallization before the formation of the dendritic structure. The universality of the principles of mathematical modeling and the relationship between critical processes of destruction, sintering of materials, and crystallization of binary alloys based on their physical commonality is shown.