Elevated-temperature creep and relaxation of torsion-tension members

Based on the assumption that each material satisfies the condition for isotropic hardening for a von Mises material, an incremental solution is developed to predict axial-strain creep curves and maximum shearing-strain creep and relaxation curves for solid circular torsion-tension members subjected to proportionate and nonproportionate stepped loading including creep in tension and relaxation in torsion. Test data are obtained from torsion-tension members made either of annealed OFHC copper at 800°F (427°C) or hot-rolled SAE 1045 steel at 950°F (510°C). The loading histories include either four stepped proportionate load changes, four stepped nonproportionate load changes, or torsion-tension loading in which the axial load remains constant and the torsional load is allowed to relax during two loading periods of the test. Each test duration is about 100 h. Good agreement is indicated between the predicted and measured creep and relaxation curves.     

Propagation of nonlinear Alfvén surface waves along a tangential magnetohydrodynamic discontinuity in an incompressible fluid

The paper considers the propagation of low-amplitude nonlinear waves over a surface of magnetic discontinuity. An equation for these waves is derived. The evolution of a sinusoidal perturbation is investigated. The discontinuity formation time is numerically determined.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 98–105, January–February, 1985.     

Laminar flow between the surfaces of two eccentric circular cylinders

The problem of laminar fluid flow in an asymmetric annular gap has been solved in earlier work in an approximation with error difficult to gauge. In the present paper, the problem is solved exactly. The velocity distribution of the flow is obtained, the mean velocity is determined, and an exact expression is found for the coefficient which determines the flow rate. An approximate expression proposed for this coefficient holds asymptotically at small eccentricities. The results are compared with experimental data.Translated from Izvestiya Akademil Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 16–20, January–February, 1984.     

A study of the shear viscosity of human whole saliva

Summary A model R-18 Weissenberg Rheogoniometer operating in the continuous shear mode was used to generate shear viscosity vs. shear rate data on male and female human whole saliva. These data were found to accurately follow the Sisko model, , whereµ is the shear viscosity at shear rate is the asymptotic shear viscosity at infinite shear rate, andK andn are constants. Data were collected on the effects of food, coffee, caffeine, and aspirin as functions of time. Studies were also made on the effects of emotional stress, donor sex and age.The saliva viscosity increased with time and then decreased to the basal value for most ingested materials. Emotional stress was found to elevate the saliva viscosity. On the other hand, no significant difference was found between the average saliva viscosities of male and female groups. Also, no significant effect of donor age was detected.

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Zusammenfassung Mit Hilfe eines Weissenberg-Rheogoniometers (Typ R-18) wurden bei stationärem Betrieb Scherviskositätskurven in Abhängigkeit von der Schergeschwindigkeit für den Speichel von Männern und Frauen gemessen. Man fand, daß sich die Meßwerte hinreichend genau durch ein Sisko-Modell, , beschreiben lassen, woµ die Scherviskosität bei der Schergeschwindigkeit die asymptotische Scherviskosität bei unendlich großer Schergeschwindigkeit sowieK undn weitere Konstanten bedeuten. Diese Messungen verfolgten die Wirkung von Nahrung, Kaffee, Coffein und Aspirin als Funktion der Zeit. Untersucht wurde weiterhin der Einfluß von emotionaler Spannung, sowie Geschlecht und Alter der Spender.Die Speichelviskosität stieg bei den meisten eingenommenen Stoffen mit der Zeit zuerst an, um danach wieder auf den Normalwert abzusinken. Ebenso fand man, daß emotionale Spannung eine Viskositätserhöhung hervorruft. Dagegen wurden bei Gruppen von Männern und Frauen keine signifikanten Unterschiede gefunden, und ebenso wurde kein gesicherter Einfluß des Alters festgestellt.

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With 4 figures and 6 tables     

Unsteady state diffusion of vapour in a closed tube

Results of one-dimensional calculations for unsteady state diffusion of a vapour in a closed tube are compared to calculations (a) for unsteady state diffusion of a vapour in an open tube, and (b) for heat conduction in a finite slab and an infinite slab. In the cases of (b) the effect of the convective term in the transport equation is absent.The total pressure is calculated and differences in the two cases are explained.An experiment is described in which the pressure increase in a closed tube due to the diffusion of water vapour in dry air is measured as a function of time. The experimental results agree quite well with the theoretical predictions. The results of this investigation may be used for the experimental determination of the diffusion coefficient of a vapour in a gas and in pressure measurements in systems with an evaporating liquid.Nomenclature a thermal diffusivity - D diffusion coefficient - w mean particle velocity - g particle flux in the laboratory system - g* particle flux in a system moving with the mean particle velocity w - L length of the tube - n number density of molecules - n _vs saturation number density of vapour molecules - p pressure - p _vs saturation pressure of the vapour - t time - z distance from the liquid surface - N total quantity of evaporated liquid     

Some theorems in the theory of small deformations superimposed on a finite deformation of a hyperelastic material of grade 2

The equations for small deformations superimposed on large deformations of a hyperelastic material of grade 2 are formulated and applied to derive a basic integral relation that is used to establish generalized Betti, Clapeyron, work and energy theorems. Theorems of minimum and complementary energy are deduced essentially from an energy criterion of super-stability, and these are used to prove uniqueness of solutions to the static and dynamic, mixed incremental boundary value problems. These results use a certain generalized kinetic energy functional that is assumed positive definite; and this property and the reciprocal and energy principles are exploited further to establish some theorems in the theory of small free vibrations.     

Surface-strain measurements on a hemispherical shell using holographic interferometry

A method is presented for using real-time fringe counting and double-exposure single-hologram interferometry to measure surface strain on pressurized hemispherical shells. An aluminum shell is employed for experimental verification of these techniques. Surface-strain variations caused by a defect in the aluminum wall are detected and measured. Strain-gage arrays are used for comparison of experimental results. Bendix Kansas City Division is a prime contractor to the Atomic Energy Commission.     

Behavior of a rigidly plastic cylindrical shell exposed to internal pressure

A law for conservation of energy is used in solving a system of equations describing the one-dimensional motion of an ideally plastic incompressible shell exposed to an expanding polytropic gas in equilibrium. Analytic expressions are obtained for determining the stress and velocity fields in the shell as a function of the displacement of the internal shell boundary.Translated from Zhurual Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 172–176, May–June, 1975.     

Elastic waves in crystals and anisotropic media

The results of investigation of propagation of elastic waves in anisotropic media are discussed taking into account the two-dimensional problem of a source in an infinite medium and the Lamb problem for a half-plane. The media considered in the investigation are those for which the equations of motion under plane deformation conditions are characterized by four constants.