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  • Simulation of thermal creep inhomogeneous thick-walled cylinder axisymmetric

    The complete cycle of flat axisymmetrical problem solving is given in this paper: from getting the main resolving equation to solving the practical problem of polymeric tube creepage. Two non-linear laws of “stress-deformation” union are used: Maxwell-Gurevich law and Maxwell-Tomson law. Camparison and analysis of the obtained data are given, as in some cases it is enough to use Maxwell-Tomson equation than to use more complex Maxwell-Gurevich union equation. Solving of the problem is given with the use of numerical method – finite difference method. In the case of the temperature field, all physical-mechanical parameters of the material (elastic and relaxation) are taken as the temperature function. Thees, the non-uniformity of the material is considered. To determine the temperature field Furje heat transfer equation is used.

    Keywords: axisymmetrical problem, non-uniformity, creepage, Maxwell-Gurevich union equation, Maxwell-Tomson union equation

  • Flat axisymmetric problem of thermoviscoelasticity for polymer cylinder

    The technique of determining the stress-strain state of the polymer thick cylindrical shells in flat tension conditions with effects of temperature and creep deformation. As the law of the relationship between stress and strain is used nonlinear equation of Maxwell-Gurevich. Solution is performed numerically by finite element method.

    Keywords: nonlinear creep, cylinder, the Maxwell-Gurevich equation, finite element method, relaxation viscosity, viscoelasticity, high elasticity modulus, plane stress and temperature.

  • Plane strain condition polymer of the cylinder in terms of thermoviscoplastic

    The resolving equations for determining stress-strain state of thick-walled polymeric cylindrical shell under plane strain state with changes in temperature and highly elastic strains. Into law that describes the relation between stress and creep strain, the nonlinear equation of Maxwell-Gurevich. The solution is performed numerically using the finite element method.

    Keywords: nonlinear creep, plastic cylinder, highly elastic deformation, the equation of Maxwell-Gurevich, finite element method, viscoelasticity, modulus of viscoelasticity, plane strain state, temperature.

  • The model is equally stressed cylinder on the basis of Mohr's theory of strength under pressure and temperature effects

    Solved the inverse problem for a thick-walled cylinder, experiencing temperature and force action, under the plane of the axisymmetric problem of elasticity theory. By the variation of the modulus of elasticity, in which the cylinder is equally stressed by the Mohr's theory of strength. The problem is reduced to a differential equation of the first order. This equation was solved numerically, using the Runge-Kutta method of fourth order.

    Keywords: thick-walled cylinder, optimization, heterogeneity, method, Runge-Kutta, temperature, flat axisymmetric problem

  • Differences of fundamental laws of government purchases existing in system

    The comparative analysis of two main current laws in the field of government procurements the Federal law No. 223-FZ and the Federal Law 94-FZ is considere  

    Keywords: contract auction, government procurements, electronic platforms, federal law, municipal order, public institutions, business concerns

  • Mesurement of torque of rotating drives

    Device of torque measurement of rotating shafts of different technical systems is presented in this article. Device was maiden by digital radio channel. Methods of device calibration are described. Examples of measurements of different mechanisms shafts are presented.

    Keywords: tenzometric torque, digital radio channel.