Shock-recovery experiments

In this chapter, we will review the effects of shock-wave deform.ation on material response after the completion of the shock cycle. The techniques and design parameters necessary to implement successful shock-recovery experiments in metallic and brittle solids will be discussed. The influence of shock parameters, including peak pressure and pulse duration, loading-rate effects, and the Bauschinger effect (in some shock-loaded materials) on postshock structure/property material behavior will be detailed. 

Shock-recovery experiments by Gray [10] were conducted to assess directly if the strain-path reversal inherent to the shock contains a traditional microstructurally controlled Bauschinger effect for a shock-loaded two-phase material. Two samples of a polycrystalline Al-4 wt.% Cu alloy were shock loaded to 5.0 GPa and soft recovered in the same shock assembly to assure identical shock-loading conditions. The samples had two microstructural... 

G.T. Gray III, Shock Recovery Experiments An Assessment, in Shock Compression of Condensed Matter—1989 (edited by S.C. Schmidt, J.N. Johnson, and L.W. Davison), North-Holland, Amsterdam, 1990, 407 pp. 

P.S. Decarli and M.A. Meyers, Design of Uniaxial Strain Shock Recovery Experiments, in Shock Waves and High Strain Rate Phenomena in Metals, (edited by M.A. Meyers and L.E. Murr), Plenum, New York, 1981, 341 pp. 

An important aspect of micromechanical evolution under conditions of shock-wave compression is the influence of shock-wave amplitude and pulse duration on residual strength. These effects are usually determined by shock-recovery experiments, a subject treated elsewhere in this book. Nevertheless, there are aspects of this subject that fit naturally into concepts associated with micromechanical constitutive behavior as discussed in this chapter. A brief discussion of shock-amplitude and pulse-duration hardening is presented here. 

In an experiment in which a sample is subjected to controlled shock loading and preserved for post-shock analysis, the shock-recovery experiment, the quantification, and the credibility of the experiment rest directly upon the apparatus in which the experiments are carried out. Quantification must be established with two-dimensional numerical simulation and this can only be accomplished if the recovery fixtures are standardized. The standardized fixtures must be capable of precise assembly so that the conditions actually achieved in the experiment are those of the simulation. 

Shock-recovery experiments were performed using a propellant gun (4> = 30 mm) at the National Institute for Materials Science. The projectile was a 4-mm-thick stainless-steel plate embedded in the front of a high-density polyethylene sabot. The annealed plagioelase with samarskite was encapsulated in a cylindrical container made of SUS304 stainless steel. In addition and for reference, starting plagioelase was also shock-loaded. It is well known that the peak pressure depends on the initial porosity of material [15]. Tlie samples were... 

I. Martinez, A. Deutsch, U. Scharer, Ph. Ildefonse, F. Guyot, and P. Agrinier, Shock recovery experiments on dolomite and thermodynamical modeling of impact-induced decarbonation. J. Geophys. Res. 100(B8), pp. 15,465-15,476 (1995). 

Deformed quartz samples obtained from shock-recovery experiments were generally investigated with TEM (transmission electron microscopy) to study their planar deformation features. Furthermore, several studies on the atomic-scale structure of diaplectic quartz glass have been carried out by using X-ray diffraction and IR (infrared) and Raman spectroscopy techniques. In the next section, some recent structural investigations of diaplectic quartz glass will be reviewed. 

In this study, as an initial step, annealing and shock-recovery experiments were carried out on plagioclase to understand (1) the possible mechanisms of volatile lead redistribution and (2) the disturbance of U-Th-Pb systematics during shock metamorphism. 

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