Measurement of release wave speed in shock-compressed polycrystalline alumina and aluminum

Values of release wave speed in shock-compressed polycrystalline alumina and aluminum (2024) have been measured to 400 and 260 kbar, respectively. These values, as well as previous data for aluminum and iron, have been compared with fourth-order finite strain extrapolations of the longitudinal sound speed V_p. For alumina in the pressure range 200–300 kbar and for α iron and ∈ iron the observed release wave speeds fall below any reasonable extrapolation of V_p. In the range 360–400 kbar the data for alumina indicate that M(∂^2M/∂ P^2) ≃ −50 (where M and P are longitudinal modulus and pressure, respectively); this value is in approximate agreement with Graham's ∼200-kbar data on elastic shock compression of single-crystal aluminum oxide. For aluminum the data indicate a value for M(∂^2M/∂ P^2) of 2.7±5.7

The effect of magnetic pinch pressure on boron nitride, cadmium sulfide, graphite, silica glass, and some other materials.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1970.Bibliography: leaves 129-136.Sc.D

Dynamic Strength of Brittle Materials

Author Institution: The University of Texas at AustinSlides presented at the 3nd Annual Photonic Doppler Velocimetry (PDV) Conference and Workshop held at Sandia National Laboratories, Albuquerque, New Mexico, September 3-4, 2008

Measurements of the longitudinal modulus of Pierre clay shale at varying strain rates

The propagation speed of finite-amplitude compressional waves of strain-rate 10^3 - 10^4 sec^(-1) in Pierre clay shale have been measured using shock wave techniques. The inferred longitudinal modulus perpendicular to the bedding is approximately a factor of four higher than that measured by others in uniaxial strain tests at strain rates of 1-5 sec^(-1). The present shock wave speeds measured in the laboratory and in-situ finite-amplitude explosive experiments measured by others correlate more closely with field seismic velocities than with laboratory uniaxial strain measurements. Elastic properties of this highly saturated friable material measured parallel to the bedding are less sensitive to sampling disturbances than those measured in the perpendicular direction

A COMPARISON OF HALF AND QUARTER SPACE PENETRATION INTO GRANULAR MEDIA

In this study, two experimental techniques are compared for the purpose of visualizing projectile penetration at speeds ranging between 60 and 150 m/s into granular media. The two techniques are half space penetration into a transparent synthetic soil surrogate and quarter space penetration of an opaque natural sand and transparent soil surrogate against an observation window. In both techniques a pneumatic projectile accelerator was employed to launch the projectiles, and high-speed imagery was employed to visualize the penetration events unintrusively. Transparency in transparent targets was achieved by saturating angular fused quartz with a refractive index matched pore fluid made of sucrose. Comparison of both techniques suggests that their results are complimentary. In particular, the terminal depth of penetration is not significantly inhibited by shooting in quarter space. Additionally, both techniques permitted visualizing distinct dilation zones ahead and around penetration. Each technique offers a number of distinct advantages. In particular, half space penetration reduces the possibility of projectile diversion and is much safer, whereas quarter space penetration allows for visualizing penetration into opaque targets at a finer scale than that achieved in half space penetration

Dynamic Strength of Transparent Materials

Author Institution: The University of Texas at AustinSlides presented at the 4th Annual Photonic Doppler Velocimetry (PDV) Workshop held at the University of Texas, Austin, Texas, November 5-6, 2009