Development of temperature-compensated resistance strain gages for use to 800°C

This paper describes the development and evaluation of temperature-compensated resistance strain gages for use to 800°C. These gages included single-element gages and double-element half-bridge gages. The filament of single-element gages was fabricated from specially developed Fe–Cr–Al–V–Ti–Y alloy wire. When bonded to high-temperature Ni-based alloy GH39 after stabilization at 800°C for one hour, the apparent strain from room temperature to 800°C was less than 2000 m/m. Double-element gages were fabricated from Pt–W–Re–Ni–Cr–Y alloy wire (active grid) and Pt–Ir alloy wire (compensating grid). When bonded to different high-temperature alloy specimens and stabilized, and when ballast resistance in series with the compensating grid adjusted suitably, the gages' apparent strains from room temperature to 800°C were less than 2400 m/m.Effects of preoxidization of Fe–Cr–Al wire on the characteristics of the single-element gages are described.     

Problem of Increasing the Survivability of Two–Stage Ballistic Guns

The paper proposes methods for increasing the survivability of light–gas guns, including new designs and nonconventional modes of shot. It is established theoretically and experimentally that a decrease in the cone angle of the conical adapter to 2.5 — 3° leads to a severalfold increase in the survivability of the high–pressure chamber. A compound piston with a liquid or gel–like filler is designed. The mode of shot from a light–gas gun with superlight pistons and without a diaphragm is justified and tested experimentally. Conical and measuring adapters with liners made of thermally– and wear–resistant alloys are designed to prevent ablation of the light–gas gun barrel.     

Characterisation of non-linear viscoelastic foods by the indentation technique

A method to determine the non-linear viscoelastic constitutive constants from indentation force–displacement data corresponding to different indentation speeds has been developed. The method consists of two parts. In the first part, the force–displacement data is expressed as two functions which represent the strain and the time-dependent responses, respectively. From these functions, the time-dependent constants and the instantaneous force–displacement response are obtained. In the second part, the strain-dependent variables are determined from the instantaneous force–displacement response through an inverse analysis based on the Levenberg–Marquardt method. The method was verified by numerical experiments using the properties of cheese as examples.     

Heterogeneity of Plastic Flow of Zirconium Alloys with a Parabolic Law of Strain Hardening

The specific features of plastic–strain macrolocalization at the stage of the parabolic law of strain hardening in samples from industrial zirconium–based alloys are considered. It is shown that in predeformed blanks, zones with a different character of plastic–strain localization are formed. It is also shown that the strain–localization macropattern can be used as a characteristic of the susceptibility of a material to further plastic form–changing, for example, upon tube rolling. The sign of fracture of alloys upon plastic deformation is revealed. The scale effect in the formation of localizedplastic–flow zones is shown and studied.     

The nonlinear evolution of two-dimensional and three-dimensional waves in mixing layers

The authors consider problems connected with stability [1–3] and the nonlinear development of perturbations in a plane mixing layer [4–7]. Attention is principally given to the problem of the nonlinear interaction of two-dimensional and three-dimensional perturbations [6, 7], and also to developing the corresponding method of numerical analysis based on the application to problems in the theory of hydrodynamic stability of the Bubnov—Galerkin method [8–14].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhldkosti i Gaza, No. 1, pp. 10–18, January–February, 1985.     

Determination of mechanical properties of fiber–matrix interface from pushout test

For ceramic matrix composites, the pushout test is the most widely used test for finding the two mechanical properties of the fiber–matrix interface – (1) the coefficient of friction and (2) the residual radial stress. Experimental measurements from the pushout test do not directly give the values of these two mechanical properties of the fiber–matrix interface, but need to be regressed to theoretical models. Currently, approximate theoretical models based on shear–lag analysis are used for regression. In this paper, the adequacy of the shear–lag analysis model in accurately finding the mechanical properties of the fiber–matrix interface is discussed. An elasticity solution of the pushout test based on boundary element method is developed. Regressing one set of available experimental data from a pushout test to both shear–lag analysis and boundary element method models gives values differing by 15% for the coefficient of friction but similar values for the residual radial stress. Parametric studies were also conducted to show the difference between the shear–lag analysis and boundary element method results for factors such as fiber to matrix elastic moduli ratios, coefficient of friction and fiber volume fractions.     

Nonequilibrium ionization accompanying hypersonic flow of carbon dioxide gas over blunt bodies

A study is made of the nonequilibrium ionization in the shock layer when carbon dioxide gas flows over cones with spherical noses at velocity 4–7 km/sec, the density of the oncoming flow being 10^–8-10^–5 g/cm³. The influence of admixtures of nitrogen and sodium on the electron concentration is investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 183–186, January–February, 1981.     

Analysis of behavior of graphite on the basis of nonlinear heredity theory

The behavior of graphite is described on the basis of the nonlinear heredity theory taking account of the temperature factor in the range 20–3000 °C. The necessary characteristics are obtained from, the data on creep and from the stress-strain diagrams. A physical interpretation of the obtained results is attempted.Translated from Zhurnal Prikladnoi Mechaniki i Tekhnicheskci Fiziki, No. 2, pp. 76–82, March–April, 1971.     

Emission and radiative cooling of xenon plasma behind a strong shock front

A numerical and experimental investigation of the emissivity and radiative cooling of xenon plasma in strong shock waves with Mach numbers M=16–45, including experimentally up to M=28, has been made. It is shown that under these conditions the equilibrium temperature behind the shock wave can be reduced by cooling by 1.5–2 times.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 155–162, January–February, 1992.     

The spectrum of normal oscillations of an elastoplastic medium with dissipation

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 4, pp. 108–112, July–August, 1993.     

Influence of rarefaction on the unsteady impingement process of an underexpanded supersonic jet onto a perpendicular obstacle

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 6, pp. 78–83, November–December, 1991.     

Solution of the planar linear filtration problem in layered soils

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 6, pp. 119–122, November–December, 1991.     

Numerical investigation of the heating of condensed media by volume heat sources

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 6, pp. 22–28, November–December, 1992.     

Estimate of the temperature field in a compressible medium

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 1, pp. 23–26, January–February, 1992.     

Anomalous light absorption by a turbulent plasma

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 6, pp. 32–38, November–December, 1992.     

Heat and mass transport in bundles that move and give off gas

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 6, pp. 96–103, November–December, 1992.     

Circulatory flow in the inter-jet zone of a system of free turbulent jets

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 4, pp. 97–99, July–August, 1993.     

Phenomenological model of creep under variable loads

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 4, pp. 123–127, July–August, 1993.     

Oscillations of an ice sheet under a periodically varying load

Translated from Prikiadnaya Mekhanika i Tekhnicheskaya Fizika, No. 5, pp. 141–146, September–October, 1992.