457 research outputs found

    Steady-State Creep Analysis of Pressurized Pipe Weldments by Perturbation Method

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    The stress analysis of pressurized circumferential pipe weldments under steady state creep is considered. The creep response of the material is governed by Norton's law. Numerical and analytical solutions are obtained by means of perturbation method, the unperturbed solution corresponds to the stress field in a homogeneous pipe. The correction terms are treated as stresses defined with the help of an auxiliary linear elastic problem. Exact expressions for jumps of hoop and radial stresses at the interface are obtained. The proposed technique essentially simplifies parametric analysis of multi-material components.Comment: 17 pages, 6 figure

    On the Use of the First Order Shear Deformation Models of Beams, Plates and Shells in Creep Lifetime Estimations

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    Numerical creep-damage life-time predictions of thinwalled structures are discussed with respect to the cross section assumptions used in engineering models of beams, plates and shells. The first part of the paper is devoted to the comparative numerical study of a pipe bend based on shell and solid type finite elements available in the ANSYS code. The second part demonstrates the possibilities and limitations of the first order shear deformation beam theory in connection with creep damage analysis. The results show that the beam and shell models provide a satisfactory accuracy of time dependent deformation and stress solutions for the von Mises stress controlled creep response. The dependence of the creep strain rate on the kind of the stress state induced by the damage evolution requires to refine through-the-thickness approximations of displacement and stress fields used in the first order shear deformation engineering models. The errors of the creep solution with the shell or beam model result in the underestimation of displacements and the wrong edge zone stress redistributions

    Поняття та види форм цивільно-правового захисту особистих немайнових прав фізичної особи, що забезпечують її соціальне буття

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    Науменко, К. С. Поняття та види форм цивільно-правового захисту особистих немайнових прав фізичної особи, що забезпечують її соціальне буття [Електронний ресурс] / К. С. Науменко // Форум права. – 2014. – № 2. – С. 296–300. – Режим доступу: http://nbuv.gov.ua/j-pdf/FP_index.htm_2014_2_52.pdf.Науменко К. С. "Поняття та види форм цивільно-правового захисту особистих немайнових прав фізичної особи, що забезпечують її соціальне буття." Форум права 2 (2014): 296–300.Досліджено поняття форм цивільно-правового захисту особистих немайнових прав фізичної особи, що забезпечують її соціальне буття, визначені та охарактеризовані їх основні види, а також запропоновано власну класифікацію вказаних форм.This article explores the concept of forms of civil law protection of moral rights of an individual to ensure its social being defined and described their main species and proposed its own classification of these forms.Исследовано понятие форм гражданско-правовой защиты личных неимущественных прав физического лица, обеспечивающих его социальное бытие, определены и охарактеризованы их основные виды, а также предложено собственную классификацию указанных форм

    Edge Effects in Moderately Thick Plates under Creep-Damage Conditions

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    The late F.P.J. Rimrott has published during his scientific life more than 200 refereed articles and conference papers. Various papers among them were devoted to the creep and plasticity analysis in metallic thin-walled structural elements mostly published in the period from 1958 till 1964. With regard to this early period below we discuss finite element solutions for moderately thick plates under creep-damage conditions based on shell and solid type finite elements. The results illustrate the time-dependent stress redistributions in the edge zones. We show that the transverse normal and shear stresses may have a significant influence on the damage evolution and must be considered in numerical lifetime estimations

    Solution of Creep-Damage Problems for Beams and Rectangular Plates Using the Ritz and the Finite Element Method

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    Numerical Treatment of Finite Rotation for a Cylindrical Particle

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    A problem for a rotation of a rigid cylindrical body in a medium is analyzed based on the laws of dynamics. The resistance moment is taken into account. For the numerical solution equations governing the rotary motion are formulated in terms of the right angular velocity and the rotation vector. The equations are solved numerically applying the Runge-Kutta method. The results illustrate the time variation of the unit vector spanned on the longitudinal axis of the body. By neglecting the moment of viscous friction the numerical results agree well with the classical analytical solution

    Numerical Analysis of a Steam Turbine Rotor subjected to Thermo-Mechanical Cyclic Loads

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    The contribution at hand discusses the thermo-mechanical analysis of a steam turbine rotor, made of a heat-resistant steel. Thereby, the analysis accounts for the complicated geometry of a real steam turbine rotor, subjected to practical and complex thermo-mechanical boundary conditions. Various thermo-mechanical loading cycles are taken into account, including different starting procedures (cold and warm starts). Within the thermal analysis using the FE code ABAQUS, instationary steam temperatures as well as heat transfer coefficients are prescribed, and the resulting temperature field serves as input for the subsequent structural analysis. In order to describe the mechanical behavior of the heat-resistant steel, which exhibits significant rate-dependent inelasticity combined with hardening and softening phenomena, a robust nonlinear constitutive approach, the binary mixture model, is employed and implemented in ABAQUS in two different ways, i.e. using explicit as well as implicit  methods for the time integration of the governing evolution equations. The numerical performance, the required computational effort, and the obtained accuracy of both integration methods are examined with reference to the thermo-mechanical analysis of a steam turbine rotor, as a typical practical example for the numerical analysis of a complex component. In addition, the obtained temperature, stress, and strain fields in the steam turbine rotor are discussed in detail, and the influence of the different starting procedures is examined closely

    Experimental Research of the Diffraction and Vavilov-Cherenkov Radiation Generation in a Teflon Target

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    Geometry of Vavilov-Cherekov (VChR) radiation when an electron moves close to a dielectric target is in analogy to diffraction radiation (DR) geometry. In this case we may expect DR generation from the upstream face of the target besides that VChR. The joint observation of these booth types of radiation is very interesting from the pseudo-photon viewpoint, which is applicable for relativistic electrons. Unexpected results obtained in our experiment insist on reflection about nature both DR and VChR. The experiment was performed on the relativistic electron beam of the microtron of Tomsk Polytechnic University.Comment: This article will be published in Journal of Physic