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Results of an experimental study on the deformation and failure of nature-inspired cellular structures under compression at high strain rates are presented. Tests are conducted on specimens with the Schwarz primitive geometry, modeled with different volume fractions (ϕ), as well as on solid specimens. The specimens are fabricated from polylactide polymer using 3D printing. An increase in compressive strength and elastic modulus is observed with increasing strain rate at constant ϕ. Specific energy absorption values are determined for the cellular structures studied. The Gibson-Ashby relationship for cellular structures is confirmed to hold under high-strain-rate loading.

A numerical study is performed to investigate the influence of vibrational excitation and relaxation of sulfur hexafluoride (SF₆) molecules on the gas-dynamic structure and stability of high-speed microjets issuing from axisymmetric sonic micronozzles with diameters ranging from 10 to 110 μm. Direct numerical simulation of the gas flow is conducted by solving the unsteady three-dimensional Navier-Stokes equations using a two-temperature model for relaxing flows. The study is carried out over a wide range of Reynolds numbers determined by the micronozzle diameter. The influence of vibrational relaxation of gas molecules on the mode composition and spectral characteristics of disturbances, as well as on the length of the laminar region of the microjets, is observed.

A solution to the problem of the pressure field in an oil and gas reservoir with a hydraulic fracture connecting an injection well and a production well is obtained. The solution is constructed in the Laplace-Carson transform space using an asymptotic method. Analytical expressions for the pressure field in the fracture are derived in the quasi-stationary approximation. An approximate formula for calculating the pressure field in a hydraulic fracture is proposed. Computational experiments are performed using numerical inversion algorithms and the obtained analytical expressions. Spatiotemporal pressure distributions are constructed for realistic values of reservoir and fracture parameters. Based on an analysis of the computational results, the patterns of pressure field formation in a reservoir with a hydraulic fracture are refined. A comparison of the numerical calculations with the analytical relationships shows that the proposed analytical formula provides accuracy sufficient for practical purposes over a time period comparable to the production lifetime of real oil and gas fields.

The nonlocal theory of microstructural deformation of thin plates is applied to derive an equilibrium equation for a thin isotropic nanoplate along with the corresponding boundary conditions. An approach to constructing a solution to this equation for a rectangular nanoplate with simply supported edges is proposed, employing Chebyshev polynomials of the first kind and the collocation method. The deflection of the nanoplate midplane and the bending moments are analyzed as functions of a nonlocal nanoscale parameter.

The mechanical properties of a new composite-diamane-reinforced copper-are investigated using molecular dynamics simulations. Young's modulus and tensile strength of the copper-diamane composite are determined to be 117 GPa and 16.4 GPa, respectively. These values can be greater provided that the number of diamane layers in the composite is increased.

An experimental study of hydraulic fracturing of thick-walled concrete cylinders with a central hole is conducted using a high-pressure fluid test setup. The cylinders are made of sand-based concrete with GTs 50 alumina cement. Estimates of the ultimate pressure obtained using local and nonlocal failure criteria are compared with experimental data. Satisfactory agreement between the calculated ultimate loads and the experimental failure data under nonuniform stress conditions is shown to be achieved with nonlocal failure criteria.

The propagation of a rectilinear crack at the interface of dissimilar materials is investigated. A two-parameter (dual) elastic-plastic failure criterion for mixed-type cracks is proposed. This criterion includes a deformation criterion formulated at the tip of the initial crack and a force criterion formulated at the tip of a fictitious crack. The lengths of the initial and fictitious cracks differ by an amount equal to the length of the process zone. Because the crack path at the interface between materials is curved, the fracture angle is determined using the maximum tangential stress criterion based on the asymptotic expansion of the stress field in the vicinity of the crack tip, taking into account non-singular terms. A modified Leonov-Panasyuk-Dugdale model of the end zone of a sharp internal crack is used to describe the process zone. The parameters entering the resulting analytical model are analyzed. The dimensionless geometric parameters of the structure are determined numerically using the finite element method. A system of two nonlinear equations is obtained for the critical length of the process zone and the critical load under mixed-type (complex) stress state conditions. The shape and dimensions of the process zone in the vicinity of the crack tip in a nonlinear elastic material are determined using the von Mises criterion.

A VT-6-10% B₄C cetmet composite is produced using direct laser deposition (laser additive manufacturing). The effect of thermal post-treatment on the microstructure and properties of this composite is investigated. After heat treatment, the (α+γ) matrix structure is found to transform into an (α+β) structure, β-Ti is stabilized, the concentration of secondary phases (TiB, TiC_1-x, TiB₂, V₂B₃) increases, and the α₂-Ti₃Al intermetallic compound is formed. Thermal post-treatment leads to an increase in microhardness (up to HV0.3 = 651) and improved wear resistance (wear volume decreases by 7%, and the friction coefficient by 0.08). These results confirm the effectiveness of heat treatment for optimizing the structure and enhancing the wear resistance of additively manufactured titanium matrix composites.

Approaches to the topological optimization of lattice composite structures aimed at improving their weight efficiency for use in rocket and space technology are investigated. Traditional filament winding methods and advanced technologies such as continuous-fiber 3D printing are considered; these enable the creation of micro-lattice structures with thin ribs and biomimetic properties. The application of the SIMP method in continuum and discrete models is demonstrated for a cylindrical spacecraft body shell. A comparison of various lattice structure designs shows that the weight of these structures is 18.5% lower when using the SIMP method compared to the traditional approach.

Results of the conceptual development of a vacuum aerodynamic facility based on the vacuum system of the AT-303 wind tunnel at the ITAM SB RAS are presented. The layout, geometry, design features, and advantages of the proposed facility are described. Its operating parameters and performance characteristics are evaluated.