The formation and development of cracks in the sample of ferromagnetic material in magnetized condition were researched. It was shown that magnetic state of material of friction surface most substantially influences the process of its brittle or quasibrittle fracture if cracks open perpendlcularly to magnetization vector. The criterion of unintentional growth of crack in magnetic field was established.
The technology of the optimal design when designing the structure of the rotor disc for turbomachines is showed. The features of the organization of computer-aided design of gas turbine engine rotor are considered. The calculations of gas turbine engine rotor parts optimal form were made. Structural optimization (shape optimization) was applied to optimal design of compressor disk depending on various factors of loading and optimization criteria.
The problem of mathematical analysis of demographic data was investigated for data, where information on migration flows is taken into account implicitly. Regression techniques, neural networks and stochastic analysis were used for the mathematical analysis of demographic processes. Two age groups were considered: young (0 - 39 years) and elderly (40 - 70 years). While development of stochastic models the theory of Markov chains and transition matrix were used. The parameterization and model identification were conducted according to Rosstat data.
The solution of the equations of motion of Newtonian fluids (Navier-Stokes equation) in vector form, containing a projection of speed and rotor speed, is considered. There was analyzed the axisymmetric laminar flow of a viscous incompressible fluid in the initial section of entrance to the circular tube, where the flow is described by only two velocity components.
The article describes the main aspects of the static tensile testing of round uniaxial samples and processing gained results with the aim of obtaining the mechanical and strength characteristics of materials, which are used for further obtaining of criteria for the destruction of structures. The paper addresses some problems of numerical modeling of the mechanical behavior of test specimens, as well as gives recommendations on the use of standard characteristics in the construction of chart of material properties.
An empirical formula for calculating the critical speed of transportation of monodisperse and polydisperse mineral slurries was proposed based on the analysis of experimental data and known empirical relationships.
When studying the stability of armored equipment assemblies at lateral blasting it is necessary either use a real object, or apply special stands. These tests are very expensive and tend to cause significant structural damage. The article presents calculations of simplified scheme for lateral blasting. Lateral blasting is by an equivalent by impact vertical blasting with reduced distance. The proposed approach can significantly reduce the cost and simplify the experiment, which reduces the amount of explosives and allows multiple-choice tests.
The paper presents the results of numerical and experimental investigation for evaluation of strength of bolted connection of parts of armored equipment under dynamic impact, namely, high-speed impact pressure from the explosion of ammunition (TNT blocks, grenades). The comparison of calculated and experimental data was made.
The problem of bifurcation of thin-walled cylindrical shell under proportional subcritical loading by axial compressing force, torque and internal stress in the deviatoric space by A. A. Ilyushin's strain was investigated. The relationship of stress and strain is adopted in accordance with the defining relations of the above-mentioned hypothesis. For determinative functions of plasticity there were used approximations, which were offered by V. G. Zubchaninov.
The approximate analytical for solving problems of forced oscillations f mechanical systems with discrete degrees of freedom, taking into account dry friction forces. Dry friction is replaced by an equivalent viscous resistance. For this purpose, the method of own functions for systems with discrete degrees of freedom is used to allow replacing the original system with some equivalent system. Thus there is postulated the equality of frequencies of original and present systems. The proposed method is illustrated by the example of the oscillating system with two degrees of freedom.
The article discusses the correlation algorithms of signal processing in passive radar systems using the signals from third-party sources. A two-stage algorithm for correlation processing, which can significantly reduce the computational cost, is proposed. The calculation of the computational complexity of the proposed algorithm and the accuracy of estimation of signal parameters on the signal-to-noise ratio are provided.
The article discusses the analog methods of suppressing the signal of the transmitter in the receiving channel in passive radar systems using the signals from third-party sources. An analog method of compensation transmitter signal in the receive path for multi-position passive radar systems is proposed. The results of experimental verification of the proposed method are shown.
The article presents a scheme of the friction machine for triboengineering tests of solid lubricating coatings at elevated temperatures and loads. The results of experimental studies of some composite solid lubricating coatings are shown.
There are shown the results of application of an axisymmetric rigid-plastic finite element membrane model to the analysis of a circular steel sheet stretching process under action of a punch with profile, which consists of two circular arcs with small radii. The failure of the deformed shell is computationally revealed in the form of strain localization.