Home – Home – Jornals – Advanced Search

The problem of fluid withdrawal (or injection) from a reservoir into a well in the presence of a hydraulic fracture perpendicular to the wellbore in the mode of a constant pressure difference between the wellhead and the reservoir is considered. Analytical solutions are obtained that describe the evolution of pressure in the fracture and fluid flow into the well. Approximate solutions are constructed using the method of successive change of stationary states. The comparison of exact and approximate solutions of problems for determining the pressure fields in the fracture and the volumetric flow rate of fluid from the well into the fracture is carried out and it is shown that they practically coincide (the relative difference does not exceed 1-2%). In this case, the calculation time for approximate solutions is significantly reduced. This contributes to the creation of effective calculation algorithms for transient modes of well operation in reservoirs with complicated reservoir characteristics. The influence of reservoir characteristics of a reservoir and a fracture on the evolution of pressure in the fracture and fluid flow into the well is analyzed.

The results of simulation of the process of unsteady fluid filtration in a formation penetrated by a well, which is crossed by a vertical hydraulic fracture of finite length, are presented. Using the method of integral Laplace transformations, an analytical solution of the system of equations describing fluid filtration in a formation and a fracture is constructed. Based on the analysis of the obtained solutions, the main characteristic features of the studied filtration process in the system reservoir - fracture.

A variant of the refrigerator emitter made of aluminum alloy with anti-meteoroid protection of the tube with a coolant in the form of a bumper, which is a radiating surface, is presented. An approximate method for calculating the stationary thermal state and pressure losses in the device has been developed. A prototype was made and tested. It is shown that the calculated and experimental data are in good agreement. A computational analysis of an efficient (efficiency parameter is equal to 3.27 kg/m2) protected (the probability of non-damage within two years is equal to 0.97) device made of aluminum alloy with a power of 570 kW is performed when the coolant is cooled from 250 to 110oC.

The shortcomings of the classical mathematical theory of plasticity are investigated, on the basis of which the processes of plastic deformation of metals are developed and studied. Using the previously proposed physical and mathematical theory of plasticity of metals, the process of plastic structure formation of the 1570P alloy (Al-Mg-Sc system) was studied, and the applicability of this theory to the formulation and solution of boundary value problems of plasticity in the development of modern technical devices was shown.

The problem of bending of a plate with arbitrary holes and cracks is solved with the use of complex potentials of the theory of bending of thin electromagnetic elastic plates. Moreover, with the help of comformal mapping, expansion of holomorphic functions into the Laurent series or Faber polynomials owing to satisfaction of boundary conditions by the least squares method, the problem is reduced to an overdetermined system of linear algebraic equations, which is then solved by the method of singular expansions. Results of numerical investigations for a plate with two elliptical holes or cracks and for a plate with a hole and a crack (including an edge crack) are reported. The influence of physical and mechanical properties of the plate material and geometric characteristics of holes and cracks on the basic characteristics of the electromagnetic elastic state is studied.

In this study, the Rayleigh-Ritz method is used to analyse the vibration of a point-supported rectangular plate with a concentrated mass. The deformation and the first-order natural frequency under various working conditions are calculated. The results are compared with those obtained by the finite element method.

The critical load (force) is estimated for a space with a disk-shaped crack, in the case when a concentrated force acts on its edges along the circumference. It is shown that it is impossible to determine the ultimate force with the help of classical fracture criteria, so a structural strength criterion formulated for axisymmetric problems is used. The relationship between fracture toughness and crack size is investigated and a two-criteria fracture diagram is constructed.

Using the nonlinear equations of elasticity theory and the geometric theory of defects, a cylindrical dislocation in an incompressible Mooney - Rivlin body is investigated. A cylindrical dislocation consists of two hollow concentric cylinders, one of which is inserted into the other and glued after a corresponding symmetrical deformation. The approaches of the classical theory of elasticity and the geometric theory of defects are compared, which made it possible to give a physical interpretation of the tensor momentum energy density in the Einstein equations for a cylindrical dislocation.

Based on the modified couple stress theory and stress relaxation phenomenon, the governing equation of motion for a double viscoelastic nanoplate system is established, and the bending analysis of the system is performed. Using Navier's method, an analytical solution of the transverse relative deflection for two nanoplates is obtained. The effects of geometrical and physical factors on the bending behavior of the system are discussed. It is concluded that the transverse relative deflection of two nanoplates depends upon the relaxation time, ratio of the delayed to initial extensional elastic moduli, and damping parameters.

The paper presents the results of tests of a system for monitoring the rolling surface of freight car wheelsets in motion using dynamic strain measurement. The research was carried out at a test ring under the conditions of multiple repetition of train load to evaluate the reproducibility of the results of strain measurements. During each passage of the train through the measuring section, a high-speed system with a sampling frequency of 64 kHz measured the strain of the rail neck caused by the impact of the wheels of the rolling stock. A specially developed software was used to automatically identify defective wheels from the obtained data and determine the dynamic force of wheel impact on the rail. The repeatability of strain measurement data was evaluated by comparing them with the results of visual and measuring control of the rolling stock conducted before the beginning of the tests.