Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session V4: Experimental Developments VI |
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Chair: Daniel Dolan, Sandia National Laboratories Room: Renaissance Ballroom C |
Thursday, June 30, 2011 4:00PM - 4:15PM |
V4.00001: Velocity spectra from explosively driven powders and balls Matthew Briggs, James Faulkner, Lawrence Hull, Michael Shinas The capability to measure velocity distributions using Photon Doppler Velocimetry (PDV) has given rise to much data that were not measurable with velocimetry techniques available before 2004. In our PDV measurements on explosively driven metals, we have often seen a single velocity disappear in a wide distribution of velocities. We have attributed this to HE gases, metal pieces, or a mix emerging from cracks in the metal after it fails. However, we are unaware of any experiments that support this interpretation. We have completed a short series of experiments using X-rays, cameras and PDV on explosively driven powders and balls that show PDV spectra similar to what we observed in our experiments in which the metal fails. We will present these spectra to help workers interpret their velocity spectra. [Preview Abstract] |
Thursday, June 30, 2011 4:15PM - 4:30PM |
V4.00002: Surface Shear Strain Measurements in Sweeping Wave Experiments Lawrence Hull, James Faulkner, Matthew Briggs Sweeping wave experiments create conditions of greater shear than corresponding one-dimensional motion experiments, and are of current interest for material damage characterization. Sweeping waves are also important with regards to the spectrum of applications of explosives driving metals. The intensity of the shear developed in a sweeping wave experiment may be monitored using crossed beams of Photon Doppler Velocimetry (PDV). During the time the material is traversing the volume defined by the crossed beams, the interferometer is measuring the velocity of the same mass element (approximately) from two directions. It is known that PDV measures the velocity component that lies along the beam direction, so that with crossed beams, two independent directions are simultaneously measured and therefore the \textit{vector} velocity (both magnitude and direction) are captured. The vector velocity is readily related to the strain rates on the surface (after removing the rigid rotation rates), and the equations are integrated to obtain the strains. [Preview Abstract] |
Thursday, June 30, 2011 4:30PM - 4:45PM |
V4.00003: Embedded optical fibers for PDV measurements in shock-loaded, light and heavy water Patrick Mercier, Jacky Benier, Pierre-Antoine Frugier, Michel Debruyne, Cyril Bolis In order to study the shock-detonation transition, it is necessary to characterize the shock loading of a high explosive plane wave generator into a nitromethane cell. To eliminate the reactive behaviour, we replace the nitromethane by an inert liquid compound. Light water has been first employed; eventually heavy water has been chosen for its better infrared spectral properties. We present the PDV results of different submerged embedded optical fibers which sense the medium with two different approaches: a non-intrusive optical observation of phenomena coming in front of them (interface, shock wave) followed by the mechanical interaction with the shock wave. [Preview Abstract] |
Thursday, June 30, 2011 4:45PM - 5:00PM |
V4.00004: Shock Ejecta Entrainment in Gas Michael Furnish Paired tin shock ejecta experiments, with and without gas fill, are used to study the ability of optical velocimetry diagnostics (specifically, PDV) to track ejecta motion. The vacuum ejecta experiments use Asay foils and PDV to characterize ejecta properties, and the gas ejecta experiments use PDV. FFT analysis of the PDV signals gives at least a qualitative indication of the presence of such ejecta and of its motion. Can quantitative information about the areal density of the ejecta be obtained from the PDV records? For modest amounts of ejecta (allowing enough light to reach the free surface and return to the probe to give a strong free surface velocity signal), the FFT amplitudes are roughly proportional to the ejecta areal density, where the proportionality constant depends on the shape and size distribution of the ejecta particles (which is consistent for the two samples in each pair). A caveat is that PDV only measures the motion of ejecta with particle sizes exceeding the 1550 nm light wavelength. [Preview Abstract] |
Thursday, June 30, 2011 5:00PM - 5:15PM |
V4.00005: Simultaneous Photonic Doppler Velocimetry and Ultra-high Speed Imaging Techniques to Characterize Pressure Output of Detonators Michael Murphy, Steven Clarke Detonator output directed into both ambient air and polymethylmethacrylate (PMMA) samples is simultaneously investigated using ultra-high speed, time-resolved schlieren/shadowgraph imaging and photonic Doppler velocimetry (PDV) measurements. In air, one-dimensional measurements of explosive cup position are made from the time-resolved image sequences and are compared to time-integrated velocity curves obtained from the PDV data. The results demonstrate good agreement that validates using the two methods concurrently. In PMMA, both average and instantaneous shock velocities are calculated from 1-D measurements of shock position. Velocity-Hugoniot data for PMMA is utilized to map the shock velocity calculations to corresponding values of mass velocity and shock pressure. Simultaneous PDV data describing the motion of the explosive cup/PMMA interface is used to determine the mass velocity and pressure at the interface, and to compare to the mass and shock pressures calculated from the imaging data. [Preview Abstract] |
Thursday, June 30, 2011 5:15PM - 5:30PM |
V4.00006: A Novel Use of PDV for an Integrated Small-scale Test Platform Carl Trujillo, D.T. Martinez, M. Burkett, J.P. Escobedo, E.K. Cerreta, G.T. Gray III To examine the high strain and high strain rate response of structural metals a dynamic extrusion technique has been developed at Los Alamos National Laboratory. In this study, several structural metals (Copper, Tantalum, and Zirconium) were accelerated up to velocities of 700 m/s and extruded through a high strength steel die. A novel use of PDV (Photonic Doppler Velocimetry) has been employed to track the time and distance of the evolved deformation through the die. This integrated small-scale experiment is used to study and provide in-situ data, assisting in the modeling and understanding the dynamic response of materials. Time and distance data, modeling efforts, and the influence of crystallography and texture will be presented. [Preview Abstract] |
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