[en] A semi-local smoothing spline of degree n and class C^p is a function defined on an interval, having p continuous derivatives on that interval, and coinciding with a polynomial of degree n on the subintervals forming its partition. The domain of each polynomial is a subinterval on which m + 1 values of the approximated function are given, but in order to construct the polynomial, it is necessary to know M ≥ m + 1 values (m and M are determined by the class and the degree of the spline). The additional values can be borrowed from the adjacent subintervals. When constructing an S-spline in the periodic case, the problem of additional values is solved on the basis of periodicity, but in the nonperiodic case, one is expected to define the lacking values of a function beyond the domain. The present paper is aimed at nonperiodic two-sided S-splines whose construction does not require additional data.

[en] A new method has been developed for the corrosion protection of steel parts: gas-phase coating application. The resulting coating is characterized by high density, chemical resistance to aggressive media, and good surface adhesion. This method may be used for parts of complex shape. The static and fatigue failure of БСт.3сп, 40, and Э10 steel is investigated, in the presence of nickel coatings of different thickness, applied at different temperatures.

[en] In this paper, new method for determining the mechanical characteristics of nanoparticles in a heterogeneous mixture is proposed. The heterogeneous mixture consists of a thermosetting epoxy resin and silicon dioxide powder of different dispersity. The mechanical characteristics of such a material at a constant concentration for nanopowder are experimentally determined. Using existing formulas for obtaining effective characteristics, the Lame coefficients for nanoparticles of various sizes are calculated. The dependence of the elastic characteristics on the particle size is obtained. (paper)

[en] The influence of the laser beam parameters (power, motion velocity, and focus position) on the characteristics of the track being formed (size, elemental composition, and microhardness) is studied. If the difference in the laser radiation absorption coefficients in the heat conduction and keyhole regimes is taken into account, then the track sizes can be determined by a unified dependence on the energy parameter. The effect of the laser beam on the chemical composition and microhardness of cermet (WC-NiCrBSi) tracks is studied. Regardless of the track formation regime, these parameters are determined by a dimensionless parameter, which describes the degree of dilution of chemical substances. It is found that a track with the maximum mass fraction of tungsten and the greatest value of microhardness is formed at small values of the dimensionless parameter, which corresponds to the heat conduction regime. The microhardness of the deposited cermet structure is observed to be 4–5 times higher than the microhardness of the substrate material.

[en] The work is dedicated to the creation of new ceramic-composite materials based on boron carbide, nickel and using a laser welding in order to obtain three dimensional objects henceforth. The perspective way of obtaining which has been suggested by the authors combined two methods: cold spray technology and subsequent laser post-treatment. At this stage, the authors focused on the interaction of the laser with the substance, regardless of the multi-layer object development. The investigated material of this work was the metal–ceramic mixture based on boron carbide, which has high physical and mechanical characteristics, such as hardness, elastic modulus, and chemical resistance. The nickel powder as a binder and different types of boron carbide were used. The ceramic content varied from 30 to 70% by mass. Thin ceramic layers were obtained by the combined method and cross-sections of different seams were studied. It was shown that the most perspective layers for additive manufacturing could be obtained from cold spray coatings with ceramic concentrations more than 50% by weight treated when laser beam was defocused (thermal-conductive laser mode). (paper)

[en] Hardware items are one of the products for mass consumption. Rolled metal for cold forging shall have the required ductility, uniform mechanical characteristics along the mill length, corresponding chemical composition and shall be free from internal or superficial defects. Standard mechanical characteristics have been reviewed in this document and fracture criteria of calibrated rolled steel 40X have been calculated after its isothermal treatment at different temperatures in nitre bath and subsequent drawing with different deformation degrees. Comparison of synergy fracture criteria showed that rolled stock, treated as per the proposed conditions: bath patenting at the temperature of 400°C and drawing with reduction rate of 5% and 10%, are more preferable, comparing to processing conditions, existing in the industry. (paper)

[en] We have studied the influence of corrosive environment on the mechanism of changes in fatigue resistance of automotive structural steels. Analysis of the experimental data has shown that the fatigue resistance of metal materials in corrosive environments is reduced significantly with the increased time of testing. This, in turn, causes a continuous decrease in fatigue curves in the multi-cycle area without reaching the endurance limit. We have identified the factors affecting the resistance to fatigue failure: the medium and its aggressiveness; stress cycle frequency, shape and asymmetry. The presence of a corrosive environment makes it problematic to determine the moment of origin of a macro crack, necessary for the analytical assessment of the time before its appearance. The proposed use of the current sag curves under the sample cyclic loading will allow to fix the moment of the crack origin and to determine the speed of its subsequent propagation. This allows to optimize the choice of structural materials for machines taking into account the operating conditions and to justify the technological manufacturing process in order to reduce material consumption, increase durability and maintainability. (paper)

[en] Results of experimental and numerical investigations of the process of creating coatings from a titanium–aluminum intermetallic compound by using an additive method are presented. It is demonstrated that the process of intermetallic compound formation is limited by the rate of titanium dissolution and diffusion in the aluminum melt. The proposed method can be applied for hardening titanium plate surfaces for their exploitation at high temperatures and pressures.