Method of designing explosive-driven magnetic field generators

A method of designing explosive-driven magnetic field generators that allows us to establish a dependence between the parameters of the generator circuit, in which the greatest energy release occurs under a time-invariant resistive load, is described. The problem of switching two-dimensional generators to a load whose resistance linearly increases with temperature is analytically solved as an example. The theoretical possibility of designing a generator in which the power released under the resistive load R(t) varies in a specified way with time is demonstrated. Types of current pulse, power, and energy released in the load are studied in the case of different generator circuit parameters.Translated from Zhurnal Prikladnoi Mekhaniki Tekhnicheskoi Fiziki, No. 1, pp. 120–127, January–February, 1976.The author to wxpress his appreciation to E. I. Bichenkov for useful remarks.     

Flow of a viscous liquid in a bent tube of finite length that undergoes deformation

A study is made of the closed flow of a viscous incompressible Newtonian liquid in a deformed tube with a section used as a peristaltic pump connected to a given hydraulic load. The time-average flow rate of the liquid (blood) in the external section is determined, together with the pressure difference across the load and the condition for the absence of hemolysis.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 177–179, March–April, 1981.     

Plasticity aspects of interfacial fracture for polymer/glass specimens

Experimental results suggest that the interfacial fracture resistance is minimal for approximate near tip Mode I accompanied by positive and negative near tip Mode II. Finite-strain FE analysis is made for an elastic–plastic medium bonded to an ideally elastic medium with an interface crack. Small-scale plasticity conditions are invoked and examined in relation to the elastic–plastic stress distribution along the bond line. Plasticity engenders a tendency to turn near tip biaxiality towards pure Mode I regardless of the mixed-mode loading. High levels of hydrostatic stress are attained. For different mode mixities of the applied load, the dependence of the elastic–plastic normal bond stress on load level is examined. It is found that under positive Mode II loading, the normal bond stress σ_yy tends to saturate as the load level rises. This does not occur for Mode I and negative Mode II loading. In addition, deformation patterns inside the plastic zone are examined for mixed-mode situations. A displacement criterion based on the normal bond crack opening suggests a dependence of the critical load level on the extent of mixed mode. Under positive mode II fracture, traces of the ductile material are found at the top of the elastic substrate. Some of these conclusions appear to be consistent with the fracture patterns observed for LD-polyethylene/glass interfacial mixed-mode fracture.     

Influence of cyclic loading on crack growth kinetics in a viscoelastic orthotropic plate made of a composite material

The kinetics of crack growth in a viscoelastic orthotropic plate made of a composite material is analyzed. The external load is the superposition of a cyclic load and a constant tensile load. The level of the tensile load is assumed to exceed the amplitude of the cyclic load. The kinetic curves are compared with the constant tension curves. The effect of the cyclic component is studied.Translated from Prikladnaya Mekhanika, Vol. 40, No. 9, pp. 116–122, September 2004.     

Effects of partial crack–face contact for the bending of thin shell structures

The physical occurrence that crack surfaces are in contact at the compressive edges when a flat or a shell is subjected to a bending load has been recognized. This article presents a theoretical analysis of crack–face contact effect on the stress intensity factor of various shell structures such as spherical shell, cylindrical shell containing an axial crack, cylindrical shell containing a circumferential crack and shell with two non-zero curvatures, under a bending load. The formulation of the problem is based on the shear deformation theory, incorporating crack–face contact by introducing distributed force at the compressive edge. Material orthotropy is concerned in this analysis. Three-dimensional finite element analysis (FEA) is conduced to compare with the theoretical solution. It is found that due to curvature effect crack–face contact behavior in shells differs from that in flat plates, in that partial contact of crack surfaces may occur in shells, depending on the shell curvature and the nature of the bending load. Crack–face contact has significant influence on the stress intensity factor and it increases the membrane component but decreases the bending component.     

Interaction of moderately strong shock waves with a cylinder

The load and force acting on an infinite circular cylinder diffracting a moderately strong shock wave (pressure ratio across the front 1.01–5) are found. The process is simulated mathematically by means of a finite-difference scheme of second order of accuracy. For = 1.4, systematic calculations have been made in a narrow range of shock strengths, which has made it possible to obtain detailed characteristics of not only the transient stage of the process but also the steady state.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 113–119, March–April, 1979.     

Stability of shells of revolution made of granular composite with damageable components

Shells of revolution made of a granular composite material with microdamageable components are studied. Microdamages are simulated by spheroidal pores filled with a damaged material. The concentration of pores increases with increasing load. The problem is formulated using the concept of continuous load and the Kirchhoff-Love hypotheses. Solutions are presented for shells of positive and zero Gaussian curvature.Translated from Prikladnaya Mekhanika, Vol. 40, No. 9, pp. 105–115, September 2004.     

On the connection between the principal components of the stress and permeability tensors of porous media

The dependence of the flow properties of rocks on the conditions under which they are loaded is one of the least studied questions in the general problem of the connection between the physical properties of porous systems and the loads acting on them. The experimental [l] and theoretical [2, 3] studies so far made have dealt primarily with the dependence of the permeability of oil and gas collector rocks on the hydrostatic compression to which they are subjected. In the present paper, a connection is established between the parameters of a nonuniform anisotropic load and the permeability tensor of rock.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 173–177, January–February, 1984.     

Creep buckling of an eccentrically loaded column

A number of experimenters investigating the buckling of columns at elevated temperatures [1–3] have noted a significant scatter of the experimental values of the buckling time. Below, an attempt is made to account for this scatter in terms of eccentricity in the application of the load.     

Thermoelastic Contact of a Shroud Ring and a Cylinder under Unsteady Friction-Induced Heat Release

Mathematical formulation is performed and a solution is found for a quasi-static thermoelastic problem of contact interaction of an elastic shroud ring and a hollow circular cylinder inserted into this ring, which are compressed by a load varied along the axis of the system, under the condition of an unloaded contact over the ring surface or over the circumference contour. The radial displacements of the contact surface of the shroud ring are approximated by displacements of the surface of a long circular hollow cylinder. Unsteady friction-induced heat release caused by the action of friction forces owing to shroud ring rotation over the cylinder with a time-dependent low angular velocity is taken into account. The problem is reduced to a system of integral equations whose structure is determined by the form of thermophysical contact conditions. A numerical algorithm of the solution is proposed, and the influence of the problem parameters on the contact pressure and temperature distributions is considered. Based on an analysis of results, a conclusion is made that the character of axial variation of the compressing load has a significant effect on the distribution of contact pressure in describing the kinematic condition of interaction of bodies in accordance with Hertz’s theory.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 4, pp. 161–178, July– August, 2005.     

Analysis of the Effect of Changed Curvature and Load Distribution on the Deformation of a Flexible Long Cylindrical Shell

The effect of changed curvature and load distribution on the deflection–load relationship is studied based on the exact analytical solutions of the nonlinear problem on the deformation of a flexible long noncircular cylindrical shell with clamped and hinged edges under a nonuniform normal load. Graphs show how changes in the curvature and load parameters affect the upper critical load.     

Elevated-temperature effects on strain gages on the YF-12A wing

A general study is made of the effects of structural heating on calibrated-strain-gage load measurements on the wing of a supersonic airplane. The primary emphasis is on temperature-induced effects as they relate to slope changes and thermal shifts of the applied load/strain relationships. These effects are studied by using the YF-12A airplane, a structural computer model, and subsequent analyses. Such topics as the thermal environment of the structure, the variation of load paths at elevated temperature, the thermal response characteristics of load equations, elevated-temperature load-measurement approaches, the thermal calibration of wings, and the correlation of strains are discussed. Ways are suggested to measure loads with calibrated strain gages in the supersonic environment.Paper was presented at 1978 SESA Spring Meeting held in Wichita, KS on May 14–18.     

Interaction of a wave with an obstacle in a multicomponent two-phase medium

The author's model [1] of a multicomponent liquid medium with nonlinear limiting compression diagrams and constant coefficient of viscosity is improved by the introduction of a coefficient of viscosity that varies during the deformation. The new model is used to obtain a numerical solution to the problem of the propagation of a plane wave produced by a shock load and the interaction of the wave with a fixed obstacle. Such a problem was solved earlier [2] in the case of a viscous medium for linear diagrams of static and dynamic compression and constant coefficient of viscosity. It is shown that the nonlinearity of the diagram of static compression leads with increasing pressure first to an increase in the reflection coefficient and then to a decrease of it. If the load has a sufficient duration, the initial section of the obstacle is subject to a succession of several waves, the number of which increases with increasing duration and amplitude of the load. The calculation was made for glycerine with air bubbles. It is assumed that at pressures up to 400·10⁵ N/m² glycerine is a linearly elastic medium In this case, the dynamic compression diagram of the two-component glycerine—gas-bubble medium is linear.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 183–187, May–June, 1981.I thank Yu. A. Sozonenko for discussion and valuable comments.     

Optimization of Dynamic Plastic Deformation of Plates with a Complex Contour

A method for studying dynamic deformation of ideal rigid–plastic plates with a complex contour on a viscoelastic foundation is proposed. The method allows one to optimize the process of pulsed forming. The optimization parameters are the amplitude of the pulsed load, viscoelastic damping coefficients of the foundation, the surface density of the plate material, and the shape and supporting conditions of the edges. Numerical examples of simply– and doubly–connected plates are given. It is shown that different combinations of the control parameters of the process can ensure the same final shape of the plate formed.     

Percolation model of an inhomogeneous anisotropic medium

A model of the variation in capillary conductivity is proposed. The change in the permeability of an inhomogeneous medium under load is investigated on the basis of the percolation model [3] and is numerically modeled for cases of hydrostatic compression and nonisotropic loading. The validity of the percolation approach to the determination of the change in flow properties under load is demonstrated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 67–75, January–February, 1986.     

Investigation of nonstationary heat transfer when a hot turbulent jet interacts with a shield

An experimental and theoretical investigation has been made of nonsteady heat transfer between a shield and a hot turbulent jet impinging normally on it. A system of dimensionless parameters is found for simulating the nonsteady interaction of high-temperature jets with shields. A system of thermocouples was used to measure the spatial and temporal distributions of the temperature in a gas above a shield, and also on the surface and within the shield. A numerical investigation was made of the nonsteady heat transfer in a shield with boundary condition specified in the form of the experimental temperature distribution of the front surface of the shield and with allowance for convective and radiative loss of heat from the other surfaces of the shield. The obtained solution is used to find the characteristics of nonsteady heat transfer (the coefficient of heat transfer and the Stanton number) on the front surface of the shield. These characteristics are used to solve the problem of periodic exposure of a shield to a heat flow produced by the switching on of a high-temperature jet.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 130–138, March–April, 1979.     

Studies of a Magnetocumulative Source of Electromagnetic Pulses with a Double Inductive Energy Storage

An energy source based on a helical magnetocumulative generator with simultaneous initiation of an explosive charge on the axis was developed. The generator operates on a double inductive energy storage with current circuit breakers in each storage. The main analytical dependences of the pulse amplitude and shape on the parameters of the double inductive energy storage were obtained. In an experiment with such an energy source, a voltage pulse of 770 – 800 kV was obtained on a breaker made of electrically exploding wires. The voltage at possible load points was 1300 – 1350 kV. The duration of the voltage pulse edge from 0.1U _max to 0.9U _max did not exceed 0.5 sec.     

Convective instability of a system of horizontal layers of immiscible liquids with a deformable interface

The convective stability of equilibrium is considered for a system of two immiscible fluids which differ little in density. A generalized Boussinesq approximation is developed, making it possible to take the interface deformations properly into account. The stability of the equilibrium state of two fluids in a horizontal layer with a vertical temperature gradient is investigated. Several instability mechanisms are identified: long-wave and cellular monotonic disturbances and oscillatory disturbances. Increasing the deformability is shown to cause switching between instability mechanisms.Perm. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 32–39, March–April, 1996.     

Direct Conversion of the Energy of Laser and Fusion Plasma Clouds to Electrical Energy During Expansion in a Magnetic Field

The paper deals with the physical and electrotechnical principles of the promising method of direct conversion of the kinetic energy of an expanding plasma cloud to electrical energy by inductive generation of currents in short–circuited load coils that enclose the plasma and are oriented across the external magnetic field. An analysis of plasma deceleration by a magnetic field and transfer of plasma energy to an inductive load gave a solution of the problem in general form and the dimensionless parameters of the problem that determine the deceleration radius, the coil current, and the theoretical conversion efficiency. The role of the basic physical effects, including parasitic ones (plasma instabilities and Joule heating), influencing the real efficiency is assessed. A comparison of the results with data of experiments with laser–produced plasma clouds on a KI–1 facility and with available numerical results shows that in the optimized version of the method for conversion of inertial confinement fusion energy, a 30% efficiency can be achieved.