Key Engineering Materials Vol. 685

Abstract: This paper is devoted to improvement of application of a peristaltic transport of heavy high-viscosity materials using magnetically active material. The main problems that arise when pumping these substances are associated with their low mobility and high shear stress. In various countries of the world peristaltic pumps are increasingly used for this purpose. A fundamentally new approach to transportation of liquid and viscous media consists in using magnetic pumps. Heavy oil and highly concentrated slurry tailings mineral resources are non-conductive materials, and as a result, require the active inducement effect on the portion of the material of the working chamber of the direct channel.

Abstract: The mechanical and tribotechnical properties of sintered composites Al-Sn with small copper additives were studied. The sintering of compacts of pure metal powders mixture conducted in the vacuum furnace. It was established that copper additions up to 2% (wt.) lead to a significant increase in the strength and sharp decrease in a plasticity of Al-Sn composites. Because last, only Al-20Sn-1Cu alloy samples saved the integrity under the multiple equal channels angular pressing. The strength of treated samples significantly increased, but their compressive deformation did not exceed 0.5%. The wear intensity of Al-Sn-Cu samples under the dry friction was higher in comparison with Al-Sn composites.

Abstract: The present study is devoted to the problem of optimal loading pressure identification by the prescribed displacements vector. The framework of finite elastocreep strains is used. The problem of deformation of the material in the vicinity of microdefect was considered. Integro-differential equations for the external pressure, irreversible deformations and displacements were derived. The simple zero-order optimization algorithm like the Monte Carlo method for considering problem was proposed. The optimal strain-stress state parameters were computed and analyzed.

Abstract: The problem of shock deforming of elastic-plastic half-space with large deformation was examined. We have obtained that the deformation state can be changed in two types of simple plastic waves and two types of shock elastic waves in the case of self-similar medium motion. The speeds and characteristics of plastic waves were examined. The numerical solution of boundary value problem was found.

Abstract: The article presents the results of experimental studies of the thermoelectric characteristics of plastically deformed steels ST3, 08KP, 12H18N10T. Measurements in the area of maximum deformation of the samples were carried out. Differences in the thermoelectric characteristics of plastically deformed steels were revealed. Steel 12H18N10T has linear characteristic, and characteristics of steels ST3 and 08KP have extreme. Constant temperature between the hot and cold electrodes needs to be maintained and also the temperature of the test specimens needs to be monitored, which in the differential testing method equals to cold electrodes. Novel block diagram of a device for testing of thermos electromotive force and monitoring of the cold electrodes temperature is proposed.

Abstract: The interaction of conjugate turbulent natural convection and surface thermal radiation in an air-filled square enclosure having heat-conducting solid walls of finite thickness and a heat source has been numerically studied. The primary focus was on the influence of surface emissivity on complex heat transfer. The mathematical model has been formulated in dimensionless variables such as stream function, vorticity and temperature using k-ε turbulent model. The effect of surface emissivity on the average total Nusselt number has been defined. The distributions of streamlines and temperature fields, describing characteristics of the analyzed fluid flow and heat transfer have been obtained. The results clearly show an essential effect of surface radiation on unsteady turbulent heat transfer.

Abstract: The article reviews the problems of vibration stand development for vibration testing of technological devices with hydraulic power equipped with a switching device to create modes for tested products pre-scanning and to carry out resonance frequency tests. The proposed development will enhance the effect of such tests due to spectrally rich vibrational impact on tested products.

Abstract: This paper reports on the ways of allocating the metal particles in the propellant grain of tube cross-sectional type to provide maximum combustion efficiency of metal. Two-dimensional flow field and the burning rate law govern a transport of the burning metal particles. The analytical correlation for the optimum allocation of metal particles in the case-bounded propellant grain of tube cross-sectional type under the assumption of equilibrium two-phase flow is deduced.

Abstract: The paper presents a study of the ultrasonic impact treatment effect on the microstructure and mechanical properties of commercial purity titanium (CP-Ti). The texture, residual stresses, the size of coherent scattering region, the thickness of plastic deformation layer and the microhardness of CP-Ti specimens subjected to ultrasonic impact treatment were studied. It was found that ultrasonic impact treatment of CP-Ti specimens resulted in severe plastic deformation of their surface layer. The plastic deformation caused twin and low angle boundary formation in the surface layer. The last-named led to a crystallographic texture change, a decrease in the size of coherent scattering region, an increase in compressive residual stresses and a growth of microhardness of the surface layer of titanium specimens.

Abstract: This paper presents the technique of decomposition of form deviation based on the use of wavelet filter and Fourier transform. The method allows decomposing the total deviation into systematic, random systematic (waviness) and random components. The method testing was carried out for the statistics of the deviation of the suction side of the turbine engine compressor blade. The accuracy check of the estimates of form deviations generated by the method in a series of simulated surfaces with pre-laid characteristics was carried out. The results showed that the method of decomposition allows one to estimate exactly the components of the form deviation of the simulated surfaces in their series.