Bulletin of the American Physical Society
2005 14th APS Topical Conference on Shock Compression of Condensed Matter
Sunday–Friday, July 31–August 5 2005; Baltimore, MD
Session C3: Materials Science I: Shock |
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Chair: John Gilman, University of California, Los Angeles Room: Hyatt Regency Constellation D |
Monday, August 1, 2005 11:00AM - 11:15AM |
C3.00001: Influence of Shock Prestraining and Grain Size on the Dynamic Tensile Extrusion Response of Copper: Experiments, Modeling and Simulation George Gray III, Paul Maudlin, Michael Burkett, Ellen Cerreta, Clarrisa Yablinsky, Benjamin Henrie, Carl Trujillo, Mike Lopez The mechanical behavior and damage evolution response of high-purity Cu are influenced by strain rate, temperature, stress state, grain size, and shock prestraining. The effects of grain size on the mechanical response of high-purity Cu have been probed and are correlated with the substructural evolution during deformation. The dynamic extrusion response of shock prestrained Cu demonstrates the significant influence of grain size on the large-strain dynamic tensile ductility of high-purity copper. Eulerian hydrocode simulations utilizing the Mechanical Threshold Stress flow stress model were performed to provide insight into the dynamic extrusion process. Quantitative comparisonsĂbetween the predicted and measured deformation topologies and extrusion rate will be presented. Predictions of the texture evolution (based upon the deformation rate history and the rigid body rotations experienced by the Cu during the extrusion process) are compared with texture measurements. [Preview Abstract] |
Monday, August 1, 2005 11:15AM - 11:30AM |
C3.00002: Measurement of Hugoniot on Zr-based metallic glass Tsutomu Mashimo, Hiroaki Togo, Yuyang Zhang, Yusuke Uemura, Yoshihito Kawamura Metallic glass is a newly developed material, which has high-performance properties, such as high strength, high corrosion resistance, soft magnetism, etc. The yielding behavior of metallic glass under shock compression is a fascinating and up-to-date problem, because it has no dislocation. The Hugoniot-measurement experiments were performed on the Zr-based metallic glass by means of the inclined-mirror photographic technique and VISAR combined with a powder gun to determine the Hugoniot-elastic limit (HEL) and examine the phase transition. The Hugoniot result showed the stable high HEL stress, and also indicated a phase transition. [Preview Abstract] |
Monday, August 1, 2005 11:30AM - 11:45AM |
C3.00003: Damage progression in explosively loaded polycrystals T.A. Mason, B.L. Henrie, K.A. Thomas One of the current challenges facing researchers in the field of dynamic properties of materials is the need for a predictive modeling capability for damage and fragmentation. A series of small-scale, explosively-driven experiments were designed and executed in order to gain a better understanding of the nucleation and growth of damage under explosive loading. The interaction of varying obliquity detonation waves with the test articles was of particular interest. The material in these tests experiences a combination of hydrostatic and deviatoric stresses that is spatially and temporally varying. Variations in shot geometries and explosive load causes direct variations in the nature of the resulting damage fields in the recovered samples. The characterization of a number of samples from a test series of tantalum discs will be presented and compared to numerical analyses of the experiments. Insights gained from the post-mortem examination of the discs and the accompanying simulations will be presented. In addition, future expansions of these experiments that will give more guidance to modeling efforts will also be briefly discussed. [Preview Abstract] |
Monday, August 1, 2005 11:45AM - 12:00PM |
C3.00004: Compositional Effects on the Shock Compression and Release Properties of Alumina-Filled Epoxy Mark Anderson, David Cox, Stephen Montgomery, Robert Setchell Alumina-filled epoxy is used for encapsulation in explosively driven pulsed power devices. Its shock compression and release properties have a strong influence on device performance. Previous studies using a baseline material containing 43{\%} by volume alumina showed a complex behavior characterized by extended wave profiles and high release-wave velocities. In recent studies, these properties have been examined while changing the total alumina volume fraction, the alumina particle size and morphology, and the epoxy constituents. Reducing the alumina volume fraction in steps from 43{\%} to 0{\%} had anticipated effects on Hugoniot states, compressive wave profiles and velocities, and release-wave velocities, although release velocities changed more rapidly. Only minor effects were observed when the alumina volume fraction was held constant while varying alumina particle characteristics or the host epoxy. Thin-pulse experiments showed combined compression and release effects resulting from decreasing the alumina volume fraction. [Preview Abstract] |
Monday, August 1, 2005 12:00PM - 12:15PM |
C3.00005: Explosively Driven Shock Induced Damage in OFHC Cu R.S. Hixson, D.D. Koller, G.T. Gray III, P.A. Rigg, L.B. Addessio, E.K. Cerreta, J.D. Maestas, C.A. Yablinsky OFHC Cu samples were subjected to shock loading using plane wave HE lenses to produce a uniaxial Taylor wave profile (shock followed by immediate release). Upon arrival of the shock wave at the free surface of the sample, the wave is reflected and propagates back into the sample as a release wave. It is the interaction of initial and reflected release waves that place the material in a localized state of tension which can ultimately result in damage and possibly complete failure of the material. The peak tensile stress and its location in the material are determined by the wave shape. Damage evolution processes and localized behavior are discussed based on results from time-resolved free surface velocity (VISAR) interferometry and post shock pre-straining metallurgical analysis of the soft recovered samples. [Preview Abstract] |
Monday, August 1, 2005 12:15PM - 12:30PM |
C3.00006: Shock compression response of ferromagnetic FePt nanoparticles Z.Q. Jin, J. Li, N.N. Thadhani, Z.L. Wang, T. Vedantam, J.P. Liu The shock-compression response of ferromagnetic FePt nanoparticles has been studied with the objective of making bulk nanocrystalline permanent magnets. Chemically synthesized FePt nanoparticles (10 nm size) with a partially ordered fct structure, produced after controlled thermal annealing at low temperature, were pressed to $\sim $45{\%} packing density and shock consolidated using a three-capsule plate-impact gas-gun fixture. The recovered disk-shaped magnets were densified to a density of $\sim $90{\%} higher than the initial packing density via intensive plastic deformation of the nano-sized particles, as revealed by high resolution transmission electron microscopy. Shock compression of the nanoparticles also induced an order-to-disorder phase transition from fct to fcc structure. The disordering transition resulted in decrease of magnetic properties; however, upon subsequent annealing, the ordered structure was completely recovered and the 10 nm grain size was still fully retained. The samples showed properties with characteristics of hard magnets - energy product (\textit{BH})$_{max }$up to 14 MGOe and coercivity up to 14.6 kOe, which are higher than those of un-shocked samples. This work has been supported by US DoD/DARPA through ARO under grant DAAD-19-01-1-0546. [Preview Abstract] |
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