Home – Home – Jornals – Journal of Applied Mechanics and Technical Physics 2025 number 3

This paper presents a review of theoretical and experimental results obtained by Russian and international researchers over the past decades. The ice cover is modeled as an elastic plate. The primary focus is on the study of forced hydroelastic waves generated by dynamic loads acting on the floating elastic plate or by disturbances created by submerged sources in the fluid.

The paper presents the results of a study on erosive wear of polycrystalline diamond coatings deposited on a molybdenum substrate. Prior to deposition, the substrate surface was treated with a jet of micro-particles of either corundum or silicon carbide. The diamond coating was applied using a gas-jet deposition method from a H₂-CH₄-Ar mixture activated by a microwave discharge. It was found that preliminary surface treatment of the substrate increases the wear resistance of the resulting diamond coating.

The results of numerical modeling of electrophoresis of a single spherical ion-selective particle in a viscoelastic electrolyte are presented. The electrolyte behavior is described using the Oldroyd-B and FENE-CR fluid models. The study is limited to weak and moderate electric fields, corresponding to first-kind electrophoresis. The dependence of the electrophoretic velocity of the particle on polymer concentration and relaxation time is obtained.

The vector potential of the magnetic field is determined in the region between the inductor, the upper part of the floating zone, the liquid film, the feed rod, and the protective screen in an axisymmetric problem of crucible-free zone melting of a silicon sample with a radius of 5÷10 cm. The boundary condition at infinity is transferred to a semicircular arc connecting the feed rod to the protective screen and located at a sufficiently large distance from the inductor, which allows the problem to be considered in a finite domain. This domain is conformally mapped onto a rectangle, within which the problem of determining the magnetic field vector potential is solved. The problem is reduced to solving Laplace’s equation for the only non-zero component of the vector potential, A_φ , where φ is the polar angle, with first- or second-type boundary conditions on the edges of the rectangle. The method can be applied to calculate the variable thickness and shape of the liquid film adjacent to the lower part of the feed rod, as well as the hydrodynamic flow within it.

For the first time, various collapse scenarios have been identified for a low-density hemispherical cavity formed by gas heating during the combustion of a pulsed submillimeter electric discharge near a dielectric surface. Two distinct collapse mechanisms were observed: one driven by the loss of stability of the cavity boundary in the contact zone with the surface, and another driven by instability in the part of the cavity farthest from the surface. It was established that both “bubble” collapse scenarios occur stochastically under invariant experimental conditions. Using the PIV method, velocity field distributions in the cavity region were obtained at different time instants. Based on high-speed velocity imaging data, it is hypothesized that the specific collapse scenario realized is determined by the shape of the conductive channel at the moment of electrical breakdown.

Two methods for obtaining crack-free joints by explosive welding of low-ductility 30KhGSA steel with varying hardness have been experimentally investigated: 1. the use of welding regimes that produce a flat, non-wavy interface zone; 2. the application of a ductile interlayer, which allows the use of welding parameters corresponding to the mechanical properties of the interlayer material. A characteristic length scale was constructed to distinguish flow regimes of the material with varying deformation intensities, enabling estimation of the thicknesses of the plastic strain localization band and the region of intense plastic deformation. It is shown that the minimum interlayer thickness that avoids fragmentation during joint plastic deformation is determined by the thickness of the strain localization band. For the first time, the feasibility of explosive welding using an interlayer produced by detonation spraying has been demonstrated.

The possibility of controlling the structural-phase composition of a VT6–
B₄C titanium matrix composite during direct laser deposition was investigated. A
correlation was established between the laser processing parameters and the
resulting microstructure: changes in energy input led to changes in the
concentration of secondary phases (TiB, TiB₂, TiC). Synchrotron radiation
diffraction was employed to obtain high-resolution diffraction patterns, which were
used to determine the qualitative phase composition of the fabricated titanium
matrix composites. It was demonstrated that using a high-energy set of processing
parameters results in a significant increase in microhardness, reaching up to 750
HV_0.3.

This paper presents several aspects of the application of physics-informed neural networks using the example of a two-dimensional steady-state problem of flow around an obstacle, modeled by the Navier-Stokes equations. The influence of the activation function, quantitative parameters of the training dataset, adaptive regularization, and adaptive meshing on the quality and accuracy of the solutions is investigated within a fixed neural network architecture. The interrelation between these factors and the modeling quality is analyzed to identify optimal conditions for improving the accuracy and stability of the solutions.

A method is presented for estimating the average sound velocity in the annular space of a mechanized well, which is subsequently used to determine the gas-liquid interface (dynamic level). The proposed approach takes into account the distribution and variation of the gas composition, thermobaric conditions, and the presence of phase transitions. The key stage in solving the problem is determining the gas composition distribution from the wellhead to the gas-liquid interface. The approach is based on the laws of thermodynamics for equilibrium processes. The method has been tested on more than 100 wells across several oil fields in Western Siberia. The convergence of the analytical approach was verified by comparing its results with field experimental measurements of sound velocity obtained by echo sounding.

The primary goal of this study is to investigate the mechanism of forced transition to turbulence in the laminar boundary layer of a swept wing, dominated by crossflow instability, using spanwise-periodic arrays of cylindrical turbulators. Measurements were carried out using hot-wire anemometry in a low-turbulence wind tunnel at ITAM SB RAS (Novosibirsk) at low subsonic freestream velocities on a model of a 25-degree swept wing. The Reynolds number based on cylinder height ranged from 565 to 3613. All major characteristics of the boundary layers were obtained, which are essential for constructing transfer functions for jumps in integral boundary layer parameters-important for numerical simulation of flows over swept wings with turbulators. The turbulence spectra were shown to be consistent with the Kolmogorov and Heisenberg laws. Empirical formulas by Falkner and Hama for the evolution of integral parameters in a three-dimensional boundary layer were verified and refined. This article represents Part 2 of the study.

The propagation of a wave with a step profile and a finite-duration impulse from a liquid into a porous medium saturated with either a bubbly or a “clean” liquid is studied. The effect of such waves on a solid wall with a saturated porous layer located in front of it is investigated. It is shown that the numerical results qualitatively agree well with known experimental data.

The frequency spectrum and mode shapes of flexural vibrations of rectangular plates in contact with a liquid or gas are determined. An expression is derived for the distributed transverse load on a plate hinged along its contour. The plate surfaces are in contact with a medium characterized by varying density and pressure. The medium may be either compressible or incompressible. The effects of mean pressure, curvature of the mid-surface, and the added mass of the gaseous medium on the plate’s bending behavior are evaluated.

The deformation of an elastic body containing two thin anisotropic inclusions intersecting at a right angle is studied based on a mathematical model with unilateral boundary conditions. The inclusions intersect at an interior point of one of them, forming a T-shaped configuration within the elastic medium. One of the inclusions is debonded from the matrix, resulting in a crack. Boundary conditions on the crack surfaces are specified in the form of inequalities. To solve the problem numerically in the region with a cut, a domain decomposition method with the Uzawa algorithm is used. To determine the displacement functions of the semi-rigid inclusion, a method based on decomposing the space into a direct sum of subspaces is applied.

This paper investigates a three-dimensional normal contact problem involving an elastic wedge with one traction-free face and an infinite periodic straight-line system of rigid indenters arranged along the wedge edge (dihedral angle). The system of indenters induces infinite normal displacements on the wedge face (a special case being the half-space). To regularize the divergent kernel of the integral equation governing the contact pressures, an additional periodic system of normal forces is introduced outside the contact region. This system is aligned with the array of indenters and shares the same period. The forces in the regularizing array are equal in magnitude and directed opposite to those applied by the indenters. Two regularization cases are considered: one where the regularizing force chain is applied off the wedge edge (first case), and another where it acts directly on the edge (second case). To solve the regularized integral equation, the Galanov numerical method is employed, which simultaneously determines both the contact area and the contact pressure distribution.

Solutions of the diffusion wave type are constructed and analyzed for a system of two degenerate nonlinear parabolic equations. The problem of initiating a diffusion wave is considered for an arbitrary form of nonlinearity in the system and for arbitrary directions of motion of the zero fronts of the two target functions. A theorem is proved on the existence of four different analytical solutions depending on the propagation directions of the zero fronts. A new numerical method is proposed, which for the first time enables the solution of the problem for the case of oppositely directed motion of the two zero fronts. A new exact solution is explicitly constructed and used to verify the computational results. A numerical experiment is performed, demonstrating the convergence of the numerical method and its effectiveness across various problem parameters.

In this paper, the modified polyaryletherketone (PAEK) was used as a toughening agent to prepare the PAEK/epoxy blends. Effect of PAEK on the erosive wear behaviors of blends was also investigated by the water jet technology. The surface morphologies of the wear scars were examined. With the increased of the PAEK content, the hardness and the impact toughness showed the phenomenon of first increased and then decreased. The erosive wear resistance of the epoxy resin blends was improved significantly, especially when PAEK content increases up to 35 phr. The erosion wear rate of the specimen shows 9.1% reduction than that of unmodified epoxy resin sample. The material removal occurred on the eroded surfaces of the epoxy blends due to the micro-ploughing, cracks, micro-cutting and plastic distortion. All these results suggested that the addition of PAEK could optimize the structural strength, indicating that the PAEK/epoxy blends are suitable for erosive environments.

This study delves into the impact of low-velocity loading and thermal effects on Functionally Graded Material (FGM) circular plates crucial in aeronautical and space engineering. Examining varied conditions, the focus lies on radial displacement and transverse deformations in hot, ambient, and cold environments. Notably, findings highlight an increased likelihood of damage in hotter scenarios, emphasizing the imperative need to design FGM plates with enhanced resistance against impact loads and thermal stresses in extreme conditions. These results bear crucial implications for aerospace applications, guiding the development of FGM plates that can effectively withstand challenges in diverse environments.

This research investigates the influence of Nb₂O₅ coatings, produced by using reactive sputtering technique, on the surface of middle-tension specimens M(T), regarding fatigue crack growth curves (da/dN versus DK) under exposure to a 0.6 mol L^-1 NaCl saline solution. Results demonstrated the corrosion process occurred in the vicinity of the crack tip, where stresses are elevated, and significant plastic deformation prevails, notably influenced by slip bands that induce micro-cracks, exposing fresh material layers to the corrosive surroundings. The Nb₂O₅ coatings enhanced the fatigue-corrosion resistance of the 2198-T851 aluminium alloy. This study marks an initial step towards more comprehensive investigations into the impact of Nb₂O₅ coating on improving the mechanical properties of the 2198-T851 aluminium alloy.