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A method for controlling the physical and chemical properties of a formation in order to increase its oil recovery by injecting an acid composition GBK-F into the formation is being considered. An experimental setup has been created for physical modeling of the effect of the composition on an oil reservoir. Experiments were carried out on a flat model with a single injection of the reagent into the central well. The experimental results confirmed the effectiveness of the composition

A two-dimensional exact analytical solution of the thermal field developed during the submerged arc welding process with visualization of the thermal surface contour for analyzing the heat flow in the domain with the hybrid application of Duhamel's theorem and finite integral transform approach is obtained. The thermal field arising in submerged arc welding of thick EH36 steel plates is studied. An ellipsoidal heat source model is assumed. The developed thermal field is investigated with variations of several process parameters, such as the heat source velocity, heat input, and lag time of movement of the heat source involved in the welding process.

In this study, the effect of patient's physical activity in terms of the heart rate on the growth of the thoracic aortic aneurysm (TAA) is studied. Using medical images of the patient, a patient-specific geometry model is constructed. Then the hemodynamic parameters of the blood flow are numerically analyzed for different heart rate conditions. The simulation results show that the maximum wall shear stress, the maximum velocity, and the maximum pressure during a cardiac cycle increase by 19.1, 12.7, and 50%, respectively, as the heart rate increases from 60 to 174 beats per minute. Results also indicate that an increase in the heart rate leads to reduction of the time-averaged wall shear stress and simultaneously to an increase in the wall shear stress oscillations. According to the literature, these hemodynamic conditions are undesirable and can increase the likelihood of aneurysm development and aortic rupture.

The behavior of material under surface laser processing conditions is described taking melting into account. A Maxwellian type is presented that takes into account the change in heat capacity and viscosity with a change in temperature and material composition. This model is used as the bases to develop a model for the change in the properties of a flat layer material using a moving heat source. An algorithm for the numerical solution of the formulated problem is described. Examples are presented to show the effect of heat loss, cohesion, melting, chemical reactions and their acceleration due to the work of stress on the properties of the material

The results of a study of the influence of compaction pressure on the characteristics of radiation-protective composites based on polyethylene and boron carbide B₄C are presented. Using software modeling, the temperature range for heating a mold of a given size was selected. The required holding time of the composite was determined experimentally, and defects that arise from various deviations from the optimal temperature parameters were identified. The results of testing the strength of samples under various pressing pressure conditions are presented, and the optimal pressure value is found. A composite was obtained with the following mechanical characteristics under optimal pressing conditions: density (1.09 ± 0.01) g/cm³, bending strength (5.72 ± 0.18) MPa, sound velocity in the composite (2050.00 ± 0.01) m/s

It is proposed to use the relations of the endochronic theory of thermoplasticity to describe the nonlinear deformation of isotropic materials under non-isothermal loading. A variant of the governing relations in integral and differential form for the general loading case is given. Analytical dependences for a number of material parameters of the model were determined based on the results of uniaxial tension (torsion) tests. A numerical algorithm based on the Euler method with an internal iterative process implemented by the Seidel method is proposed to analyze the governing relations. An example of numerical calculation of the uniaxial tension of a rod under complex thermal force loading. It is shown that the calculation results are in satisfactory agreement with the results obtained using isotropic hardening flow theory

The problem of constrained torsion of thin-walled rods under the action of an end torque is considered. Using the asymptotic splitting method, a system of resolving equations was obtained that describes the combined torsion, tension-compression, and bending of the rod. To test the resulting model using the example of typical sections, a comparison was made of the stress-strain state in the rod, determined in the calculation using the developed model and three-dimensional numerical calculation by the finite element method. The resulting mathematical model was analyzed and its advantages compared to the widely used Vlasov theory were revealed. It is shown that the developed model does not contain the restrictions imposed by the hypotheses in the Vlasov theory, such as the non-deformability of the transverse contour and the absence of shear deformations on the middle surface. In a number of cases, the resulting model makes it possible to more accurately determine the emerging stress-strain state. In particular, it is shown that the developed model takes into account the presence of a boundary layer near the embedment, which arises during torsion of corner sections and makes a significant contribution to longitudinal stresses, while Vlasov’s theory does not allow one to restore the arising longitudinal stresses

A method of determining the dynamic yield strength of heterogeneous materials is proposed, based on comparisons of the processes of cavity formation in the reference and examined materials. A series of computations is performed for penetration of an extended rod into homogeneous and heterogeneous massive targets. A nonmonotonic dependence of the penetration depth on the motion velocity is derived. The yield strength limit of a heterogeneous medium is obtained from the analysis of computation results in the coordinates of the specific kinetic energy of the rod and the work of stresses on plastic strains.

Using the grid-characteristic numerical method on grids of tetrahedrons, wave processes in a composite material are simulated under the action of a pulsed shock load. An approach is proposed to increase the order of approximation of the method on an unstructured mesh in the three-dimensional case. The results of calculations of the propagation of a load impulse in a three-layer composite are presented

A two-layer rod with a box section twisted under the action of tangential stresses at angle θ is considered. It is assumed that the deformations in the rod are elastic and its lateral surface is stress-free. The layers have different elastic properties and different thicknesses. The layer contact line is assumed to be rigid, i.e., the stresses on it coincide. An exact solution describing the stress state of the given structure is constructed using conservation laws. The stress state is determined at each point of the cross section using integrals over external contours