In this paper, we present the results of experimental studies on AlSi10Mg alloy powders with various granulometric compositions. The powders were obtained by sieving standard alloy powder used in selective laser melting technology. We used energy-dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) to investigate the morphology and chemical composition of the particles, including the distribution of elements within the particles at the submicron level. The dependence of the aluminum-to-silicon percentage ratio on the particle size was established and confirmed by both EDX spectroscopy and XRD, where larger powders contained more silicon (up to a 1.3 wt.% difference). The obtained results can be used for modeling and selecting optimal parameters for three-dimensional printing with AlSi10Mg alloy powders.

Determining the thermal stress in selective laser melting (SLM) of a metal–powder composite within a single layer requires the solution of an auxiliary problem: analysis of the nonsteady heating of an isotropic half-space by a mobile laser source. The results are used in creating a surface influence function for a thermoelastic half-space.

Algorithms for taking account of the growth of damage in multilayer composites under static loads are studied. The most common defect in multilayer structures is a transverse crack in layers with a specific orientation relative to the applied load. Two types of defect are considered: transverse cracking of the layers without the formation of a complete transverse macrocrack; and the development of interlayer cracks in the vicinity of the transverse cracks. The times at which cracks appear in the transverse layer under the action of tensile loads are determined. Attention also focuses on the propagation of the cracks and the subsequent fracturing as the load increases. Failure of a composite with transverse reinforcement is seen between the fibers because the limiting deformation there is small in comparison with that along the fibers in materials with any structure. Detailed analysis of the failure of the binder between the fibers permits prediction of subsequent defect development.

The damping characteristics of hybrid composites reinforced with spherical and fibrous elastic inclusions with viscoelastic coatings are studied. It is shown that, in the composites with the particle morphology, a significant increase in the dissipation loss can be implemented and the effective loss of a composite can exceed the dissipation loss of viscoelastic coatings by a factor of more than 20. Analytical estimates of the optimum parameters of hybrid composites are proposed. The effect of possible imperfections of the composite structure on the effective dissipation properties of the composites is analyzed.

Various types of thermal regulating coating TRP K-208 Cf are used in the systems of automatic spacecraft thermal mode provision. The elements of TRP K-208 Cf, investigated in this work, belong to the class of “solar reflector” and are designed to protect ASC from excessive solar radiation, while at the same time dissipating excessive heat into the surrounding space. The elements of the thermal control coating are plates made of radiation-resistant glass of K-208 grade with step-by-step coatings on the back side. Within the framework of the research samples with different coating thickness and material of the reflecting layer were made. The article is devoted to the study of the influence of changing the mode of coating application and the thickness of the reflecting layer of the thermoregulating coating on the thermo-optical characteristics of the elements.

The processes of unsteady contact interaction of liquids described by different mathematical models with solid deformable bodies are considered. Closed mathematical formulations of unsteady contact problems in the case of various models of liquids and linear-elastic bodies are developed. The analytical solution of the nonstationary problem of interaction between an acoustic fluid and a deformable solid body is obtained. The time integral Laplace transform is used to construct the solution. The distributions of displacements and stresses in the solid body, as well as pressure and velocity fields in the fluid during unsteady contact interaction are analyzed.

The potential of digital image analysis based on the Segment Anything Model (SAM) in analyzing the morphology of single tracks obtained by selective laser melting (SLM) is considered. A digital microscope produces images of single tracks obtained at different scanning speeds and different laser source power. The images are automatically analyzed: the single tracks are classified by external appearance and their width is recorded. The quality of the initial digital images and the presence of thermal influence zones significantly affect the agreement of the measurements obtained by automatic analysis and the measurements obtained by microscopy of transverse sections.

This paper considers a non-stationary problem of heat conduction using a volumetric heat source acting in an isotropic half-space. The process of heat transfer in a half-space is described by the generalized hyperbolic Maxwell–Cattaneo equation. To construct the volumetric influence function, we represent the volumetric heat source as a concentrated source located at a point of a heat-conducting half-space. The problem of continuous heating of a half-space by a concentrated heat source is considered, and the results of calculations are given. The results of the work can be used to assess the contribution of nonstationary thermal conductivity in the processes of heat transfer in materials and structures exposed to intense heat flows (heating by gases with high enthalpy, laser surface treatment, additive technologies, etc.).

When an aircraft passes through a rainy area at high speed, the coating on the front edge of the fuselage will be continuously eroded by raindrops, causing the coating to wear, crack or even peel off. This paper uses carbon fiber T300 material as the base material, and at the different impact speeds and impact numbers, water cutting equipment was used to simulate the erosion of the coating caused by the continuous impact of water droplets. The damage morphology of samples at different damage stages was observed by digital microscope and Scanning Electron Microscope (SEM), and the damage evolution curve was established to analyze and reveal the damage behavior and damage mechanism of rain erosion. The results show that the degree of damage experienced an increasing trend with the increase of impact numbers and speed, until circular peel damage was formed; no damage occurred during the incubation period, and the curvature of the damage evolution curve increased significantly after the expansion period and eventually showed a stable expansion trend. The mechanical properties of the coating material were the main influencing factors of its rain corrosion resistance. Moreover, the axially symmetric unsteady contact problem of droplets impacting the surface of a solid deformable body was studied. And the contact area was determined based on the iterative algorithm boundary positioning method. A mathematical model and closed mathematical formula describing the unsteady interaction between a droplet and a solid deformable obstacle were proposed.

The influence of defects (splitting) on the stress–strain state of a three-layer cylindrical panel under the action of an aircraft engine jet is studied numerically, by the finite-element method. Two versions of honeycomb filler are considered. The polymer’s sheathing consists of individual polymer composite layers. Results for panels with and without defects are compared.

In this paper, we present the experimental results obtained and corresponding inverse analysis employed to determine the amplitude-dependent damping properties of laminates made of glass fiber reinforced plastic (GFRP). Free damped vibration tests of cantilever beams with different symmetric stacking sequences were performed. Logarithmic decrement analysis was used to evaluate the effective amplitude-dependent loss factor of the samples. Inverse analysis was used to find the single-ply dynamic properties based on the laminated beam theory and the complex moduli approach. It was found that the loss factors of GFRP laminates almost linearly depend on the maximum strain amplitude. The maximum value of the loss factor of unidirectional ply was realized in the transverse direction to the fibers and reached similar to 0.023 for strain amplitudes up to 0.1% in the frequency range of 20-60 Hz.

The effective dissipative properties of the whiskerized layer in modified composites formed by growing special nanostructures (whiskers) on the fiber surface are studied. The whiskerized layer consists of two phases: (1) elastic inclusions (nanowhiskers); (2) viscoelastic binder. The interphase layer is assumed to be a transversally isotropic material with a symmetry axis along the whiskers. Numerical values are given for the loss modulus of the whiskerized interphase layer, under the following types of loading: shear along the whiskers; shear transverse to the whiskers; an omnidirectional load transverse to the whiskers; and uniaxial extension along the whiskers. The influence of the materials in the inclusions and the viscoelastic matrix on the effective properties of the whiskerized layer is investigated.

Samples produced from AlSi10Mg alloy powder by three-dimensional printing (selective laser melting) with different parameters are experimentally investigated. The samples produced are tested in extension, compression, and three-point flexure. The test results are graphically displayed.

An important property of fiber composites is the interaction between the reinforcing fiber and the matrix. Monitoring and management of the fiber–matrix interaction significantly improves the interlayer strength in composites. In the present work, a simpler method is proposed for testing composites by fiber extraction from the matrix. Specifically, in determining the strength of fiber–matrix adhesion, a fiber with the matrix on only one side is employed, rather than a fiber with matrix on both sides. The method is described, and some results of its use are presented. When using the proposed method, it is simpler to produce and handle the sample and to conduct the tests.

This article presents the mathematical formulations of transient heat conduction problems corresponding to the models of classical heat conduction using the Fourier law and generalized heat conduction based on the Cattaneo–Vernotta–Lykov law (Maxwell–Cattaneo model), as well as the generalized Green–Nagdy type II and III models. The Fourier transforms in spatial coordinates and the Laplace transforms in time were used to obtain the fundamental solutions of the equations of the Maxwell–Cattaneo and Green–Nagdy type II and III models of classical and generalized heat conduction. The results were displayed graphically and analyzed. Differences between the considered heat conduction models were shown, and suggestions for their practical application were given.

The purpose of this work is to study the propagation and diffraction of unsteady waves on a thin spherical shell located in an elastic half-space. Analytical methods are used to construct the solution. The problems of diffraction of elastic waves on various types of inhomogeneities are among the most complex and topical problems of the dynamics of deformable bodies. From the applied point of view, this is explained by the fact that the information about the dynamic stress-strain state in the vicinity of these inhomogeneities is of great interest for various purposes. Moreover, the presence of inhomogeneities (inclusions, cavities, notches, local changes in properties, etc.) is an indispensable condition arising in various fields of modern engineering. Such tasks include: creation of new structures working under dynamic loads, development of new composite materials and their introduction in creation of engineering structures, modern tasks of geophysics and seismology, as well as a number of other tasks of scientific and technical character.

The action of raindrop erosion on aerospace components is considered. In supersonic flight, the damage may be significant. To evaluate raindrop impact, the external load on the surface of various composite barriers is studied experimentally. In the present work, the external load is determined experimentally, and the behavior of a composite target under the action of a water jet is studied. The parameters considered include the velocity of the water jet, its angle of incidence, and the target thickness. The results permit mathematical modeling of droplet impact on a barrier in the form of a rigidly fixed circular plate. Dynamic equations from linear elasticity theory are solved for a circular isotropic plate attached along the contour, in which the mechanical properties resemble the mean characteristics of a composite barrier.

The results of experimental studies of the impact toughness of polymer samples with lightweight lattice cores obtained by Fused deposition modeling (FDM) three-dimensional printing technology are presented. It has been established that there is an optimum volume fraction (infill percentage) at which the impact strength of the sample with the lattice core is the highest and, even, exceeds the impact strength of fully dense material with volume fraction equals to one.

An axisymmetric initial and boundary value problem regarding the impact of a liquid drop on a solid surface at constant speed is considered, for different contact angles. Mathematically, Navier–Stokes equations are used to describe the motion of each phase (liquid, air). A method of numerical solution is described, and sample calculations are presented.