Solution of inverse problem of solidification of a cylindrical ingot

An inverse problem of heat conduction that involves determination of the density of boundary heat flux providing a prescribed velocity of solidification front motion is solved by an integral method. Moscow Institute of Steel and Alloys. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 4, pp. July–August, 1996.     

Regimes of a population density described by a nonlinear reaction-diffusion model

Certain stationary and nonstationary solutions of a reaction-diffusion model are obtained. Results of a numerical simulation of problems involving boundary conditions of the first kind are presented. A classification of regimes of change in population density is determined. Engineering Physics Institute, Moscow, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 2, pp. 179–186, March–April, 1996.     

Thermal field on the surface of a material heated by a laser pulse in a narrow ring of illumination

Based on a solution of the problem of the temperature effect of instantaneous heat sources uniformly distributed in a thin plane ring on the boundary of a semünfinite body and different approximations of that solution, we constructed a dynamic model of a thermal field on the surface of a material heated by a laser pulse in a narrow ring of illumination. Scientific Center for Opticophysical Investigations Moscow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 1, pp. 55–64, January–February, 1996.     

On the moment theory of elasticity. Plane deformation. Part I

We propose a model of the moment theory of elasticity in which equations of the classical (momentless) theory of elasticity are supplemented with equilibrium equations (momental equations) and boundary conditions for couple stresses and shear strains are determined by tangential and couple stresses. As a result, the basic relationships between strains and displacements and, hence, the continuity equations for strains preserve the same form as in the momentless theory. The proposed moment theory of elasticity completely includes all basic postulates of the classical theory and supplements it in the case where the law of parity of tangential stresses is not valid. We obtain solutions of some problems which cannot be solved within the framework of the classical theory of elasticity. Moscow State Postal-Tuition Institute of the Food Industry, Moscow, Russia. Translated from Problemy Prochnosti, No. 3, pp. 103–113, May–June, 1998.     

Avogadro program: Environmental problems of heat engineering

Results of some studies of formation and transformation of harmful substances during combustion of organic fuels are presented. The studies were conducted within the framework of the program “Environmental Problems of Heat Engineering” of the AVOGADRO system. Institute of Mechanics, M. V. Lomonosov Moscow State University, Moscow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 6, pp. 921–926, November–December, 1996.     

On the moment theory of elasticity. Plane deformation. Part 2

For the problem of bending of a plate under the action of a concentrated force represented as pressure distributed over a small surface, we obtain a solution by methods of the moment theory of elasticity, the principal statements of which were given in Part 1. Moscow State Institute of Food Industry, Moscow, Russia. Translated from Problemy Prochnosti, No. 4, pp. 106–115, July–August, 1998.     

Study of radiative heat transfer in a coaxial cylindrical system with a rotating polygonal emitting prism

A numerical investigation of radiative heat transfer gives the distribution of infinite effective radiation flux that falls onto the sensing element of a pyrometer over the prism-face surface as a function of the angle of face rotation. Moscow State Institute of Electronic Engineering, Moscow, Russia, Translated from Inzhenerno-Fizichenskii zhurnal. Vol. 69, No. 1, pp. 65–71, Junuary–February, 1996.     

A method for determination of the diffusion coefficient of hydrogen in titanium alloys by chemical etching

We propose a model of absorption of hydrogen by titanium alloys in the process of chemical etching. We obtained a solution that describes the amount of absorbed hydrogen and its distribution in the metal as a function of the rate and time of etching. On the basis of the equations obtained, we developed a method for determination of the diffusion coefficient of hydrogen in a metal. The essence of the method is a sequential etching of a specimen in hydrogenated and nonhydrogenated solutions and determination of the amount of hydrogen which remains in the metal. The effective diffusion coefficients of hydrogen in titanium alloys with various structures are found. Central Institute of Aircraft Motor Building, Moscow, Russia. Tupolev Aircraft Scientific and Technical Association, Moscow, Russia. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 34, No. 4, pp. 107–112, July–August, 1998.     

Thermal state of coated solids in asymmetric cyclic heat exchange with ambient media

An analytical solution with improved convergence at the external boundary of the problem of transient heat conduction in a solid—coating system that is cyclically washed by media with different temperatures is given. The solids in question are a plate, a cylinder, and a sphere. It is suggested that the duration of adjacent half-periods, the laws of change in the temperatures of the media in each, and the heat-transfer coefficients may not be the same. Kazan Branch of the Moscow Power Institute. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 1, pp. 123–128, January, 1996.     

Stress-strain state of a drill string and marine riser under their interaction in the open SEA

We consider the problem of interaction of a marine riser with a drill string inside it under the conditions of their joint bending in a strong sea current. We derive three-dimensional equations for the statics of the string and the riser which take into account the contact interaction and friction occurring under the displacements of the drill string inside the marine riser. A method is proposed for the numerical calculation of the stress-strain state of the drill string and marine riser. As an example, for the data of well drilling in the Straits of Gibraltar, we have calculated the regions of safe displacement of the offshore drilling rig that correspond to given safety factors. ^aCentral Research Institute for Prospecting for Nonferrous and Noble Metals, Moscow.^b“Energokosmos” Scientific Technical Center, Moscow, Russia. Translated from Problemy Prochnosti, No. 1, pp. 128 – 135, January – February, 1998.     

On the moment theory of elasticity. Plane deformation. Part 3

By the methods of the moment theory of elasticity, we solve the problem of tension of a plate with restraint. We suggest equations determining the positions of the principal planes and the level of principal stresses and present expressions for the stress and strain tensors in the plane problem of the moment theory of elasticity. Moscow State Extra-Mural Courses of the Institute of the Food Industry, Moscow, Russia. Translated from Problemy Prochnosti, No. 5, pp. 82–88, September–October, 1998.     

Solution of a problem concerning the distribution of gas molecules in a layer with mirror boundary conditions

In the present work we investigate the distribution of gas molecules in a layer filled with a rarefied gas. To solve the problem, a Boltzmann model nonstationary equation is used. The distribution function is found in the form of an expansion in generalized eigenfunctions of the corresponding characteristic equation. Moscow Pedagogical University, Russia; Vologda Science Coordination Center of the Russian Academy of Sciences, Moscow, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 72, No. 5, pp. 862–869, September–October, 1999.     

Heat exchange between a substrate and substrate holder in thermal contact

The article presents the results of an experimental investigation of high-temperature contact heat exchange between the polished surface of a substrate and the rough surface of a substrate holder under various conditions of contact between them in different gas media, under vacuum, and at different gas flow rates. Moscow Institute of Electronic Engineering, Moscow, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 5, pp. 761–767, September–October, 1996.     

Discussion of a particular mathematical model for controlling steel carburization

We formulate an inverse problem of controlling the carburization of steel parts in a gas furnace, when on termination of the process the partial pressures of gases in the atmosphere are determined by the prescribed characteristics of the distribution of carbon in the surface layer of the metal. Stable and economic algorithms are suggested for solving the problem. M. V. Lomonosov Moscow State University, Moscow, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 5, pp. 794–799, September–October, 1996.     

A concept of ultimate crack resistance

The ultimate crack resistance is regarded as a two-parameter fracture criterion. The concept of ultimate crack resistance enables one to estimate the state of a material and to compute the crack resistance of machine parts in the processes of brittle, transient, and viscous fracture. In relations used for numerical analysis, the stress intensity factors are preserved but the corresponding characteristic of the material is made more complicated. Moscow Institute of Physical Engineering, Moscow, Russia. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 34, No. 5, pp. 97–100, September–October, 1998.     

Application of the energy criterion to the numerical analysis of pipelines for “leak prior to fracture”

We consider an energy fracture criterion in the form of an integral over the crack surface. The basic variational equation enables one to describe both critical and subcritical states of cracked bodies under monotonic loads by introducing special variations of crack length. By using this criterion, we deduce an equation which describes the subcritical growth of through and nonthrough cracks in pipelines, compute the amount of water flowing through the crack, and propose a generalized fracture diagram which enables one to estimate pipelines according to the the “leak-prior-to-fracture” criterion. Moscow Institute of Physical Engineers. Moscow. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 32, No. 1, pp. 67–75, January–February, 1996.     

Effect of hydrogen on the machinability of VT5-1 alloy by cutting

Alloying of VT5-1 alloy with hydrogen decreases cutting forces and increases the service life cutting tools within a certain range of concentrations of hydrogen. The most pronounced favorable effect of hydrogen on the machinability of VT5-1 alloy is observed for its concentration of 0.5wt.% and may be caused by changes in the microstructure, by the effect of hydrogen plasticization, and by the enhanced brittleness of chips. Tsiolkovskii Moscow State University of Aircraft Engineering, Moscow Russia. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 32, No. 6, pp. 107–112, November–December, 1996.     

Reduction of a class of inverse heat-conduction problems to direct initial/boundary-value problems

The authors present a method of reducing inverse problems of recovery of boundary heat fluxes by means of data of integral or differential temperature measurements on the boundary to direct initial/boundary-value problems. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 744–747, July–August, 2000.     

Experimental determination of solid–liquid interfacial energy for succinonitrile solid solution in equilibrium with the succinonitrile–(D) camphor eutectic liquid

The equilibrated grain boundary groove shapes for Succinonitrile (SCN) solid solution in equilibrium with the Succinonitrile (SCN)–D Camphor (DC) eutectic liquid were directly observed. From the observed grain boundary groove shapes, the Gibbs–Thomson coefficient and solid–liquid interface energy for SCN solid solution in equilibrium with the SCN–DC eutectic liquid has been determined to be (5.39 ± 0.27) × 10⁻⁸ K m and (7.88 ± 0.79) × 10⁻³ J m⁻² with present numerical method and Gibbs–Thomson equation, respectively. The grain boundary energy of SCN rich phase of the SCN–DC eutectic system has been determined to be (14.95 ± 1.79) × 10⁻³ J m⁻² from the observed grain boundary groove shapes. Thermal conductivity ratio of the liquid phase to the solid phase for SCN–0.16 mole % DC alloy has also been measured.     

Numerical solution of stefan problems by the method of green functions

A method for reducing a multidimensional Stefan problem to a system of Hammerstein integral equations is proposed. Application of the proposed method to numerical solution of one-dimensional nonstationary Stefan problems formulated for the cases of an internal phase front, coincidence of the phase front with the external boundary, and a movable external boundary is considered. The efficiency of the method is tested on an exactly solvable Stefan problem. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 3, pp. 564–570, May–June, 1998.