Shock Waves In Solids Research Articles

Effectiveness of foil-shaped manganin gauge in pressure measurement of shock wave in solid.

Foil-shaped manganin gauges are used for pressure measurement of shock wave insolid. Some experiments of resistance change under shock pressure are made to discussthe effectiveness of their gauges as in-material gauge. The resistance changes aremeasured as a function of shock pressure. Shock waves are generated into solid bya single-stage gas gun. Shock pressure are obtained by using the impact velocity ofprojectile and the shock compression data of standard materials, such as copper, sapphireand fused quartz. The results by the foil-shaped manganin gauge used here arein good agreement with the ones under the static pressure, while the other results undershock pressure using manganin wire by other workers have been not in agreement withstatic data. It is concluded that the foil-shaped manganin gauge used here is very useful as in-material gauge for shock pressure measurement.

Kinetic energy and temperature profiles of shockwaves in solids

Tsai and MacDonald (1973, 1978) published a critical analysis of the authors' molecular dynamic simulation of shockwave propagation. Most of their criticism was directed to the authors' definition of temperature and kinetic energy. It is shown that their analysis is incorrect and that the authors' calculation of kinetic energy is correct and the definition of temperature is reasonable. Most of the misunderstanding arose from the other not understanding that all the authors' calculations were performed in a stationary frame of reference. It is further shown that, when there is a variation in the planar velocity, the Tsai-MacDonald local kinetic temperature is neither equal to the local kinetic energy (expressed as temperature) nor does it have the characteristics of temperature.

Properties and physiological application of focused fluid shock waves

Shock waves in solids provoke tensile stresses at free boundaries (Hopkinson effect), at low impedance surroundings or at great angles of incidence. A similar phenomenon can be observed at fluid‐fluid interfaces: gas bubbles can be generated if the acoustic impedance jump and the primary pressure amplitude is sufficient for generating negative pressure (pseudocavitation). This will occur especially in the case of focused shock waves. The shock waves are generated in water by spark gap arrays or exploding wires and focused by a torus reflector. At the surface of the water a petroleum layer is arranged. In high speed schlieren‐ and shadow‐optical picture series their propagation can be observed. Quantitative measurements are made with piezoelectric transducers. The results are important for the therapy of kidneystones with shock waves: the human tissue acoustically behaves as a fluid and by the pseudocavitation tissue damages may occur. Other applications and methods to prevent tissue damages are discussed.

Mach‐Reflection of Detonation Waves in condensed high explosives

AbstractIn a cylindrical arrangement as deviced by G. R. Fowles and W. M. Isbell for the generation of Mach‐reflection of shock waves in solids Mach‐reflection of detonation waves in condensed high explosives with different detonation velocities is investigated. The process is observed directly by flash x‐ray radiography. By means of this arrangement it is possible to generate via Mach‐reflection a plane detonation wave, the Mach‐disk. Characteristics and applications of the Mach‐disk are discussed.

Simulations of shock waves in solids

Molecular dynamic shock wave simulations have been carried out for face centered cubic (f.c.c.) and body centered cubic (b.c.c.) solids using Lennard-Jones and Morse potentials for the interatomic interactions. The Hugoniot conservation relations were accurately obeyed in all of these calculations. The shock wave profiles may vary with the interatomic potential and the crystal structure, effects most clearly shown by the temperature profile near the shock front. The Lennard-Jones solids are intensitive to a change in structure but the Morse solids appear sensitive to crystal structure, at least in comparing b.c.c. with f.c.c. It was shown that the average shock wave temperature can be calculated from a combination of the Hugoniot conservation relations and the Mie-Grüneisen equation of state. The temperature calculated this way is in good agreement with the average shock wave temperature obtained in the computer simulations.

Simulations of shock waves in solids

Shock wave simulations have been carried out to 800 planes for BCC iron using a Morse potential. Analysis showed that the Hugoniot conservation relations are obeyed even for non-constant shock profiles if appropriate averages over the complete shock region are used. Various definitions of temperature for the shocked region were examined. The anomalies reported by Tsai and MacDonald (1973) were not observed.

A model for shock waves in solids and evidence for a thermal catastrophe

Shock-wave experiments and computer simulations yield a linear relation between shock velocity and particle velocity. We show that a Mie-Grüneisen equation of state combined with the Hugoniot relations matches the computer results and the experiments and leads to an explanation of the generality of the linear velocity dependence. At high shock velocities the onset of a thermal catastrophe, which results in a maximum shock compression, is predicted from our model.

Application of holographic interferometry to shock waves in solids

Double-pulse holographic interferometry has been used to determine the rear-surface displacement of a target exposed to a pulsed electron beam. The technique has been applied to the study of shock-wave propagation in a complex heterogeneous material—three-dimensional quartz phenolic. The results suggest a multiple-wave character for shock propagation in this material.

Bibliography on Shock Waves in Solids

Abstract : About 850 references are given to books, articles, and reports on theoretical and experimental aspects of shocks in solids. The topics include computer codes, composite media, and equations of state.

Report on the Seventh International Shock Tube Symposium

The Seventh Shock Tube Symposium was held 23–25 June 1969 in Toronto, Canada. Sponsored by the University of Toronto Institute for Aerospace Studies and the United States Air Force Office of Scientific Research, the meeting drew nearly 300 attendees from some 20 countries. Of the 40 invited and contributed papers, several described new shock-tube techniques while the majority presented recent experimental results and related theory in the fields of shock structure, atomic and molecular physics, radiation, plasma flows, shock waves in solids, and boundary layers. This report summarizes the principal advances presented and attempts a projection of future directions in shock-tube research. The full proceedings will be published by the University of Toronto Press; the programme was published in the Bulletin of the American Physical Society, June 1969, p. 754.

Method for Hugoniot Equation-of-State Measurements at Extreme Pressures

A brief study is described of a simple method for producing plane shock waves in solids at pressures higher than those attainable by conventional explosive methods. Mach reflection of a conically convergent shock in the specimen yields a disk-shaped front at a pressure of several megabars, depending on the type of explosive employed and the specimen material; this front is accessible to Hugoniot equation-of-state measurements. Results for copper at a pressure of 1.9 Mbar are in good agreement with published values.

Explosive-Induced Shock Waves. Part II. Oblique Shock Waves

The explosive production of oblique shock waves in solids is analyzed in the approximation that third and higher order terms in the shock strength can be neglected, and a procedure is developed for calculating the attenuation of the shocks. Application is made to the problem of determining the equation of state of the burned explosives gas.

Explosive Induced Shock Waves. Part I. Plane Shock Waves

The explosive production of plane shock waves in solids is analyzed in the approximation that third and higher order terms in the shock strength can be neglected, and a procedure is developed for calculating the attenutation of the shocks. Application is made to the problem of determining the equation of state of the burned explosive gas.

Hydrodynamic Theory of Shock Waves in Solids

The impact of two solids traveling with relative velocity of 3 km/sec or more, or the detonation of high explosive in contact with a solid, generates compression waves in which the magnitude of the stress can easily exceed 100 000 atmospheres while its duration may be but slightly, more than a microsecond. In this situation, which lies outside the realm of classical elastic behavior, all the classical criteria for plastic flow are greatly exceeded; it appears, however, that the strain rate is so high that the usual mechanisms of plastic flow cannot act, so nonplastic behavior is to be expected. There is a considerable body of evidence which indicates that metals, at least, behave very much like ideal fluids under these conditions. This evidence includes the hydrodynamic behavior of metal liners in hollow explosive charges, the anomalously low measured shock velocity in iron, and agreement between dynamic compressions measured by Walsh and the extrapolation of static data obtained by Bridgman. These data are reviewed and the plausibility of the hydrodynamic theory is discussed.

The Propagation of Shock Waves in Solids

The Propagation of Shock Waves in Solids

Kerr Cell Photography of High Speed Phenomena

Visible light photographs have been obtained of metal jets squirted from the lined conical cavities of high explosive charges. Since these jets travel through air at nearly meteoric velocities (7 to 12×105 cm/sec), their front ends are heated to incandescense and vaporized. The remainder of the jet is relatively nonluminous and is photographed by synchronizing a Kerr cell shutter (exposure time <1 μsec) and an exploding wire light source (peak intensity 4×108 candlepower) with the phenomenon. Schlieren type photography cannot be used because of the luminosity accompanying the phenomenon. Detail is obtained in the photographs by using a large lens with a seven-in. focal length. To maintain the effective aperture at f/4 requires a large Kerr cell which in turn requires a 25,000 volt pulse for its operation. The technique is used in studying the action of these jets on steel, water, glass, and Plexiglas. The technique is also used in studying the propagation of shock waves in solids and liquids when these phenomena are due to the action of the metal jets or to the more direct action of explosives.