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 L1: Inelastic Deformation, Fracture, and Spall V |
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Chair: Cyril Williams, Army Research Laboratory Room: Grand Ballroom II-III |
Wednesday, June 29, 2011 9:15AM - 9:30AM |
L1.00001: ABSTRACT WITHDRAWN |
Wednesday, June 29, 2011 9:30AM - 9:45AM |
L1.00002: Quantification of Ejecta from Shock-Loaded Metal Surfaces Brendan A. Kullback, Mark D. Carrara, Guillermo Terrones, Muhammad Hajj Mass ejecta from shock-loaded surfaces with finite disturbances were calculated for different elastic-perfectly plastic metals with the Mie-Gruneisen equation of state and with varying disturbance amplitudes (h), wave numbers (k), and geometric shapes. In our simulations, the disturbance extends periodically in the transverse direction and the perturbed free surface is subjected to a single normal shock. The total ejected mass was found to depend on kh (the product of the wave number and the initial amplitude of the disturbance) and (P/Y$_{0})^{1/2}$ (where P is the shock pressure and Y$_{0}$ is the metal yield stress). For specific shapes of the disturbance, there seems to be a unique relation between the ratio of the total ejected mass and the mass removed by the disturbance. In addition, we found the cutoff condition (kh)$_{C}$ below which no ejecta can be produced. Generally, the amount of mass ejected increases with kh. However, a striking feature near the ejecta cutoff is the existence of a finite region (kh)$_{C }\le $ kh $\le $ (kh)$_{T}$ where the ejected mass decreases with kh. For all the metals and shock conditions we have considered, the ejecta production increases monotonically for the range of kh values we have computed above (kh)$_{T}$. This effect and the global behavior of mass ejecta will be discussed. [Preview Abstract] |
Wednesday, June 29, 2011 9:45AM - 10:00AM |
L1.00003: ABSTRACT WITHDRAWN |
Wednesday, June 29, 2011 10:00AM - 10:15AM |
L1.00004: The Study of High-Speed Surface Dynamics Using a Pulsed Proton Beam William Buttler, Benjamin Stone, David Oro, Guy Dimonte, Dean Preston, Frank Cherne, Timothy Germann, Guillermo Terrones, Dale Tupa Los Alamos National Laboratory is presently engaged in development and implementation of ejecta source term and transport models for integration into LANL hydrodynamic computer codes. Experimental support for the effort spans a broad array of activities, including ejecta source term measurements from machine roughened Sn surfaces shocked by HE or flyer plates. Because the underlying postulate for ejecta formation is that ejecta are characterized by Richtmyer-Meshkov instability (RMI) phenomena, a key element of the theory and modeling effort centers on validation and verification RMI experiments at the LANSCE Proton Radiography Facility (pRad) to compare with modeled ejecta measurements. Here we present experimental results used to define and validate a physics based ejecta model together with remarkable, unexpected results of Sn instability growth in vacuum and gasses, and Sn and Cu RM growth that reveals the sensitivity of the RM instability to the yield strength of the material, Cu. The motivation of this last subject, RM growth linked to material strength, is to probe the shock pressure regions over which ejecta begins to form. [Preview Abstract] |
Wednesday, June 29, 2011 10:15AM - 10:30AM |
L1.00005: Experimental study of eject on lead surface under varied loading rate and amplitude Yongtao Chen The eject phenomena of pure lead flyer under detonation loading of varied loading rate and amplitude were studied with the help of high speed photography, VISAR, the Asay foil and a special optical probe. The mass of eject material from the lead surface may change several times with the change of loading amplitude in range of 3GPa$\sim $5GPa and the change of corresponding loading rate. After of massive material flow, total mass of which can reach tens of times by compare to the traditional eject mass, was recorded after the traditional eject particles and tightly before the flyer surface when the loading amplitude exceeded some given threshold. Formation of such kind of dispersed material flow is surely related to the shock wave or release melting (partial melting) of lead, in which cavitation and fragmentation may take place very quickly under the tension state f release wave. The loading amplitude and loading rate were controlled by varying the gap or the thickness of a porous material between the rear surface of combined flyers and the front surface of high explosive in the range of sub-millimeter. [Preview Abstract] |
Wednesday, June 29, 2011 10:30AM - 10:45AM |
L1.00006: Estimation of spectral characteristics of particles ejected from free surfaces of metals and liquids under shock wave effect Alla Georgievskaya, Victor Raevsky One of the mechanisms for shock-wave dispersion of materials is ejecta of particles from free surface after shock wave arrival to it. In many cases, the initial perturbations are roughness obtained by turning processing. Basing on general physical knowledge and the Richtmayer analytical solution, approximated equations were obtained for estimation of quantity of mass ejected from surface versus time for small initial perturbations. Numerical calculations confirmed correctness of the estimations. Authors of the work present approximated equations for estimation of spectral characteristics of particles ejected from substance surface under effect of shock wave in the liquid and solid states. The calculated spectra of particles are compared to results of tests performed in VNIIEF for determination of spectral structure of formed particles. Pressure and surface roughness were varied in these tests. At the qualitative level, the particle spectra calculated by the suggested model are in agreement with the experimental results. [Preview Abstract] |
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