Evaluation of the surface tension of a fiber

Conclusions 1. The use of central-force theory in the calculations of molecular forces gives results analogous to those obtained using the usual theories of a surface layer in an artificial fiber.2. The surface layer of the models of a fiber chosen in this paper is characterized by an extensive force which is smaller in absolute value than the internal compressive forces.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 1, pp. 12–14, January–February, 1977.     

Viscoelastic deformations of a thick-walled cylinder under prolonged exposure to gravitational stresses

A method is presented for the calculation of the stress-deformed state of an infinitely long viscoelastic thick-walled cylinder, enclosed in an elastic casing and exposed to gravitational stress in equilibrium with a system of concentrated forces, applied to the casing. The problem is solved by analyzing the flat deformation of the annular region under the influence of mass forces and unknown reactions on the outer surface, and by determining the stress-deformed state of the casing ring exposed to distributed normal and tangential loads, and to a system of concentrated forces. The solutions are then compared on the basis of compatibility of the deformations and equality of the stresses. Integral transformations are used in the calculations and an example is cited.S. Ordzhonikidze Aviation Institute, Moscow. Translated from Mekhanika Polimerov, No. 5, pp. 846–853, September–October, 1972.     

Effect of transverse shear on the stability of an orthotropic cylindrical shell with an elastic core in axial compression

The effect of transverse shear on the stability of a composite shell in axial compression has been investigated. The core is treated as an isotropic elastic cylinder bonded to the inner surface of the shell. The effect of the tangential shearing forces between the shell and the core is taken into account.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 2, pp. 267–273, March–April, 1973.     

Slip of a rigid cylinder along a viscoelastic foundation in the presence of friction

The problem of the slip of a rigid infinitely long cylinder along a viscoelastic foundation in the presence of friction forces dependent on the slip rate is solved in a linear quasistatic arrangement. The effect of the rheological characteristics of the foundation material and other factors on the point displacement of the surface in front of the moving cylinder is studied. Rather good agreement is obtained between theoretical and experimental data.Institute of Mechanics of Metal-Polymer Systems, Academy of Sciences of the Belorussian SSR, Gomel'. Translated from Mekhanika Polimerov, No. 6, pp. 1058–1064, November–December, 1974.     

Estimation of the error of approximation of the analytic solution of problems for nonlinear viscoelastic materials

Estimates are given for the error of approximation of the solution of problems of nonlinear viscoelastic media, for which the nonlinear elastic solution depends analytically on the material characteristics, the body and surface forces, and on the boundary displacements. From the integral estimates particular estimates are derived for viscoelastic materials in cases when the nonlinear elastic solution is majorized by a geometric progression or the sum of products of geometric progressions.Moscow Institute of Electronic Engineering. Translated from Mekhanika Polimerov, No. 5, pp. 827–834, September–October, 1971.     

Stability of composite shells with an elastic core

The stability in axial compression of orthotropic cylindrical shells with an elastic core is investigated with allowance for the following factors: transverse shear strains in the shell material, precritical state of stress of the core, and the moments due to the surface forces exerted on the shell by the core. The numerical results obtained are compared with the results of approximate methods in which the above-mentioned factors are disregarded.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 3, pp. 544–547, May–June, 1976.     

Analysis of solvability of boundary Fredholm integral equations of second kind in the classical problem of torsion of an elastic body of revolution

We prove solvability of the problem of elasticity theory dealing with the action of torsional forces on the lateral surface of a body of revolution. An algorithm is proposed which regularizes the degenerate Fredholm equation of second kind.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 62, pp. 26–30, 1987.     

The Problem on Evolution of a Self-Gravitating Isolated Fluid Mass That is not Subject to the Surface Tension Forces

We establish the solvability of the nonstationary free boundary problem for the Navier–Stokes equations which describes the evolution of a self-gravitating isolated fluid mass that is not subject to the surface tension forces. Bibliography: 12 titles.     

Contact problems of thermoelasticity taking account of heat production

We give a survey of papers that discuss the mathematical statement and methods of solution of contact problems of thermoelasticity taking account of heat production due to frictional forces on the surface of contact.Translated fromMatematicheskie Metody i Fiziko-Mekhanicheskie Polya, Issue 35, 1992, pp. 93–100.     

Method of solving quasistatic boundary value problems of viscoelasticity for media with time-varying properties

It is shown that, if certain conditions are satisfied, the solution of a viscoelastic mixed boundary value problem can be obtained from the solution of the corresponding elastic problem by substituting time operators for the body and surface forces or given displacements. A similar assertion is also proved for media with time-varying properties. The applicability of the method to the theory of shallow flexible viscoelastic shells is demonstrated.Moscow Lomonosov State University. Translated from Mekhanika Polimerov, No. 6, pp. 987–993, November–December, 1969.     

Effect of filler surface state on the properties of polyethylene composites

Treatment of the filler surface may either strengthen or weaken the forces of adhesion between the filler and the polyethylene matrix, thereby affecting the coefficient of linear expansion. Reduction of the adhesion by the creation of a polyalkylsiloxane (antiadhesive) film on the surface of silicate fillers leads to an increase in the coefficient of linear expansion (up to 80%) as compared with an annealed or paraffined surface. Radiation-induced crosslinking of the polysiloxane film and the polyethylene reduced the expansion coefficient. Surface treatment of the filler will reduce the wear of the composite, especially one filled with fine metal powder, the coefficient of fraction remaining unchanged.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1038–1045, November–December, 1969.     

Local buckling of compressed elements of layered viscoelastic material

The problem of local surface buckling of compressed elements of layered material is solved using the equations of the theory of multilayer plates [1, 2, 5]. The local buckling deformations are described by means of the solutions of differential-difference equations damping into the interior of the medium. The effect of compressive forces, buckling wavelength, and the elastic and viscoelastic constants of the material on the behavior of the deformations and on the thickness of the layer to which significant buckling extends is investigated. Numerical estimates are presented for the buckling parameters of compressed laminated-plastic elements.Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 816–821, September–October, 1968.     

Load-carrying capacity of a lubricant film with variable yield point

The authors examine the load-carrying capacity of a lubricant film model with a variable yield point in shear, when the change in the value of the yield point over the film thickness is determined by surface forces.Mekhanika Polimerov, Vol. 2, No. 3, pp. 383–386, 1966     

Stability of linearly viscoelastic bars made from polymer materials of variable cross section

The critical viscoelastic forces for hinged bars made from polymer materials of variable cross section changing in accordance with a power law are obtained. It is shown that these forces are proportional to the critical elastic forces of bars of variable cross section.VMEL "Lenin," Sofia. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 540–546, May–June, 1973.     

Investigation of polytetrafluorethylene surface texture

Results are given of an X-ray investigation of the formation of a textured surface layer on polytetrafluorethylene (PTFE) film and its dependence on external mechanical factors — unit load and sliding speed. It is established that the thickness of the surface texture of PTFE is determined by the relation between the processes of texture formation under the influence of frictional forces and its destruction by wear. These processes, in turn, are determined by the working parameters of the moving joint. Data on the kinetics of polymer surface texture formation in the presence of friction are extremely useful in relation to the design of efficient antifriction materials.Mekhanika Polimerov, Vol. 1, No. 2, pp. 129–132, 1965     

Inertia effects in circular squeeze film bearing using Herschel–Bulkley lubricants

Recent engineering trends in lubrication emphasize that in order to analyze the performance of bearings adequately, it is necessary to take into account the combined effects of fluid inertia forces and non-Newtonian characteristics of lubricants. In the present work, the effects of fluid inertia forces in the circular squeeze film bearing lubricated with Herschel–Bulkley fluids with constant squeeze motion have been investigated. Herschel–Bulkley fluids are characterized by an yield value which leads to the formation of a rigid core in the flow region. The shape and extent of the core formation along the radial direction is determined numerically for various values of Herschel–Bulkley number and power-law index. The bearing performances such as pressure distribution and load capacity for different values of Herschel–Bulkley number, Reynolds number, power-law index have been computed. The effects of fluid inertia and non-Newtonian characteristics on the bearing performances have been discussed.     

Thermoelastic strain in a parabolic cylinder

An exact solution of the inner and outer problems of static thermoelasticity is obtained for an isotropic parabolic cylinder whose surface temperature is representable by a Fourier integral in one variable and by Weber functions in the other variable. The boundary surface is assumed free from external forces.Institute of Mechanics of the Ukrainian Academy of Sciences, Kiev University. Translated from Vychisotel'naya i Prikladnaya Matematika, No. 67, pp. 80–88, 1989.     

Limit equilibrium of a body with a disk-shaped almost planar crack

The article deals with the spatial problem of the limit equilibrium of an isotropic elastic body weakened by a three-dimensional crack with an almost planar surface. At infinity the body is subjected to tensile constant forces of intensity p. With the small parameter method this problem is reduced to a series of problems for a body with a disk-shaped crack. The dependence of the critical load on the magnitude of the deviation of the crack surface from planeness is obtained.Translated from Teoreticheskaya i Prikladnaya Mekhanika, No. 20, pp. 21–25, 1989.     

Coupled problems of thermoviscoelasticity

The author derives a heat flux equation with allowance for the dissipation of internal forces on the basis of the fundamental equations of continuum mechanics and the thermodynamics of irreversible processes.Moscow Lomonosov State University. Translated from Mekhanika Polimerov, No. 3, pp. 415–421, May–June, 1969.     

Equilibrium compression of rubber samples in practical tests

The distribution of stresses and strains in equilibrium uniaxial compression of cylindrical and rectangular rubber specimens is analyzed with consideration for the effect of friction forces on the ends and of the nonlinearity of the relation between stresses and strains. The results obtained satisfy the basic equations of the nonlinear theory of elasticity and experimental data on the displacements of points of a rectangular grid applied to the surface of underformed specimens due to deformation.Mekhanika Polimerov, Vol. 1, No. 4, pp. 81–88, 1965