Bulletin of the American Physical Society
15th APS Topical Conference on Shock Compression of Condensed Matter
Volume 52, Number 8
Sunday–Friday, June 24–29, 2007; Kohala Coast, Hawaii
Session V4: Inelastic Deformation VI |
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Chair: Sunil Dwivedi, Washington State University Room: Fairmont Orchid Hotel Plaza II |
Friday, June 29, 2007 10:30AM - 10:45AM |
V4.00001: Statistics of Spall and Hugoniot Elastic Limit from Line VISAR Michael Furnish, Tracy Vogler, C. Scott Alexander, William Reinhart, Wayne Trott, Lalit Chhabildas Material heterogeneity appears to give rise to variability in the yield behavior of ceramics and metals under shock loading and spall conditions. The line-imaging VISAR provides a way to measure this variability, which may then be quantified by Weibull statistics or other methods. Wiebull methods assign a 2-parameter representation of failure phenomena and variability. We have conducted experiments with tantalum (25 and 40 um grains), soda lime glass, single-crystal sapphire and silicon carbide. Line-imaging VISAR data reveal an averaged velocity response analogous to point VISAR or PDV data. As well, in addition to strength variability information, this diagnostic provides statistical bounds for the velocity histories, measurements of surface distortion with time (length scales and amplitudes), and verification of sample edge effects and wave focusing. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. [Preview Abstract] |
Friday, June 29, 2007 10:45AM - 11:00AM |
V4.00002: Hydrocode modeling and an experimental study of explosively driven water jets Philip Rae, Peter Dickson, Alan Novak, Gary Parker There is currently interest in water based penetrators. The research to be presented is on the experimental and computer model optimization of designs to produce coherent high velocity (4-7 km s$^{-1})$ jets of water from a shaped charge like device. High-speed and Schlieren photography techniques have been used to record the jets produced by various design iterations and the experimental images compared to models run in the CTH hydrocode. The computer code was used to reduce the number of experiments required and to solve some initial problems with non-uniform initial jet shapes. The CTH code has been successful in modeling the observed jets, but only after careful attention was paid to the equation-of-state used for the water. Initially the jet diameter produced by the code was considerably thinner than experimentally observed. A much better match occurred when the most modern SESAME EOS table for water was used. [Preview Abstract] |
Friday, June 29, 2007 11:00AM - 11:15AM |
V4.00003: Study of the projectile impact on aluminum targets divided by water Tei Saburi, Shiro Kubota, Yuji Ogata, Yuji Wada, Toshikazu Nakanishi The impact behavior of a projectile into aluminum alloy targets divided by water was experimentally observed using high-speed video camera, and a numerical simulation was conducted using LS-DYNA. The target size was 5mm in thick, 200mm in height and width. Two target plates were positioned parallel at a distance of 120-180mm, and the space between targets was filled up with water. A SNCM steel projectile was 10mm in height, and 10mm in diameter. The projectile was accelerated by a compact accelerator using an explosive, and impacted on the first target. Impact experiments without water in the gap space were also conducted. In case without water, the projectile penetrated both two targets. On the other hand, in case that water fills up in the gap, The projectile did not penetrate the second target plate, and the both target plates were entirely and largely deformed compared with the case that water is absent. Numerical simulation of the projectile impact was conducted using a finite element code of LS-DYNA. ALE(Arbitrary Lagrangian Eulerian) method was adopted to simulate fluid-structure interaction problem. The deformation behavior of targets was confirmed by the simulation, and the importance of water effect on the deformation of the targets and the de-acceleration of the projectile velocity was shown. [Preview Abstract] |
Friday, June 29, 2007 11:15AM - 11:30AM |
V4.00004: Damaging of materials by bi-dimensional dynamic effects M. Boustie, J.P. Cuqlelandais, L. Berthe, S. Barradas, C. Bolis, M. Arrigoni, T. De Resseguier, M. Jeandin Laser shocks are most often used to produce uniaxial stress and strain into materials by irradiating a spot diameter conventionally admitted at least three times larger than the thickness of the shocked sample. By reducing the laser spot versus the sample thickness, 2D lateral waves are created earlier and their crossing during propagation stages generates traction which can yield to voids into materials (near the front loaded face). This phenomenon has been evidenced by an experimental study, including VISAR measurements which exhibit the signature of the fracture generated by these 2D effects. Numerical simulations with the explicit finite element code RADIOSS clearly evidence the origin of the 2D effects on VISAR measurements. This different mode of damaging materials by laser lateral waves can act simultaneously with the classical laser spallation produced by the uniaxial propagation (shock wave reverberation crossing the unloading). This opens new discussed prospects for the development of 2D damage models and for applications such as the debonding test of coatings on thick substrates by laser shock. [Preview Abstract] |
Friday, June 29, 2007 11:30AM - 11:45AM |
V4.00005: Examination of the spallation behavior of cerium metal Frank Cherne, Paulo Rigg, William Anderson, Jason Cooley We have conducted a series of free surface shock experiments on cerium metal at peak shock pressures from 0.9-7.6 GPa. These experiments were done to examine the elastic-plastic behavior, the solid-solid phase transition occuring at 0.7-0.8 GPa, and the spall strength of the material as a funciton of peak stress. The elastic and low-pressure plastic waves exhibit long rise times, while the post-transition plastic wave is sharp. Spallation wave profiles obtained from using optical techniques will be presented and discussed. [Preview Abstract] |
Friday, June 29, 2007 11:45AM - 12:00PM |
V4.00006: Ductile spall in copper of different structure B. Herrmann, E. Zaretsky, G.I. Kanel, S.V. Razorenov The spall signals and post mortem metallography of crystals of Cu+0.1{\%}Si solid solution and copper with sub-micron silica inclusions were studied in planar impact experiments at two different load durations. The samples contained large (4-5 mm in diameter) grains with [100] axes parallel to the sample normal. Fractography of the spall surfaces correlate with the free surface velocity histories. The main fracture surface of the Cu+0.1{\%}Si grains consists of dimples $\sim $5 $\mu $m to 50 $\mu $m diameter. The fracture surfaces of copper with silica inclusions are covered by a net of dimples of 1 $\mu $m to 5 $\mu $m size some of which contain Si particles. In both cases the grain boundaries crossing the fracture surface are partially open and covered by a fine net of tensile dimples of $\sim $5$\mu $m. The free surface velocity histories demonstrate prolonged spall fracture process for Cu+0.1{\%}Si samples and faster fracture at lower fracture stress for copper with brittle inclusions. [Preview Abstract] |
Friday, June 29, 2007 12:00PM - 12:15PM |
V4.00007: Crack-resistance and spall strength of cerium under dynamic loading. Victor Pushkov, Vladimir Ogorodnikov, Sergey Erunov There is poor knowledge on cerium characteristics under dynamic loading, such as dynamic crack-resistance and spall strength, which are important for some applications. For example, material crack-resistance is one of parameters of the model, which is used for numerical description of the dispersion process [1]. Tests were performed for determination of dynamic crack-resistance by the split Hopkinson pressure bar method. However, significant plasticity of cerium caused failure of crack-resistance determination. Therefore crack-resistance evaluation was performed by study of material spall strength $\sigma_{0}$. Considering value $\sigma_{0}$, it is possible to determine specific work for material break $\lambda $ [2], and, basing on it, then it is possible to determine crack-resistance value by the Irvine-Griffiths criterion. \newline \newline [1] A.K.Zhiembetov, G.S.Smirnov, A.L.Mikhaylov et al. Cavitational method for determination of parameters of melting of shock-compressed substances at volume expansion. Chemical Physics, 2005, v.24, {\#}10, p.57-65. \newline [2] Fracture of different-scale objects. Edited by A.G.Ivanov, RFNC-VNIIEF, Sarov, 2001. [Preview Abstract] |
Friday, June 29, 2007 12:15PM - 12:30PM |
V4.00008: Instability of an Interface Between Steel layers Acted Upon by an Oblique Shock Wave Oleg Drennov The results of experiments in which development of instability was observed on the interface between two identical metals in tight contact wich passage of an oblique shock wave through it are presented. The loading scheme is shown in figure 1. The photograph of microsection of the contact boundary after shock--wave loading is sown in figure 2. \[ \psi \] The calculations showed that perturbations develop only in the presence of a technological microgap of several micrometers between the metal layers. Unloading of the material behind the oblique shock front into the gap gives rise to considerable short -- term velocity gradient (t $\le $0.2 $\mu $s; $\Delta $U $\ge $3 $\mu $mm/$\mu $s). Simultaneously, near the interface behing the wave front there is a short--term loss of strength of the material due to thermal softening and the heterogeneous nature of the deformation. [Preview Abstract] |
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