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 C1: Inelastic Deformation, Fracture, and Spall II |
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Chair: Geremy Kleiser, Air Force Research Laboratory Room: Grand Ballroom I-III |
Monday, June 27, 2011 11:00AM - 11:15AM |
C1.00001: 2D- and 3D-explosive experiments for verification of spall and shear strengths models for some steels Evgeny Kozlov Presented are new results on the kinetics of stress relaxation on the elastic and phase precursors in hardened 30KhGSA steel (HRC 35{\ldots}40), as well as results how parameters of the main plastic wave and spall signals change throughout wedge samples and semispherical shells. Comparative study of specificities in the fracture of wedge samples and semispherical shells of 12Kh18N10T and 30KhGSA steels (HRC 35{\ldots}40) was made using optical lever method, multi-channel laser interferometry, mild recovery and calorimetric measurement of converged shells, their multi-angleshot gamma-tomography; the high-rate and heavily deformed material was investigated using optical, scanning, and transmission electron microscopy. Mechanisms of the high-rate developed deformation including issues on localization of deformation and nocrystallographic flow of crystals are briefly discussed. I'd like to express gratitude and appreciation to my co-workers V.I.Tarzhanov, I.V. Telichko, D.G. Pankratov, S.A. Brichikov, D.S. Boyarnikov, L.P. Brezgina, V.N. Povyshev and collaborators A.V. Dobromyslov, N.I. Taluts for their contribution to experimental research. [Preview Abstract] |
Monday, June 27, 2011 11:15AM - 11:30AM |
C1.00002: ABSTRACT WITHDRAWN |
Monday, June 27, 2011 11:30AM - 11:45AM |
C1.00003: Spall Response of 1100-O Aluminum Cyril Willliams, Datta Dandekar, Kaliat Ramesh Plate impact experiments were conducted to study the effects of peak shock stress, pulse duration, and loading rate on the pullback velocity of fully annealed 1100 aluminum. The results obtained from this work show a sharp increase in pullback velocity with increase in peak shock stress between 4.0 GPa and 8.5 GPa, followed by a sharp decrease up to 11.5 GPa. However, when the pulse duration was varied from 0.61 $\mu $s to 1.55 $\mu $s the pullback velocity was observed to decrease and tend towards saturation. This result is in agreement with the open literature. The key conclusion from this work is that recovery experiments are required to further probe the deformation mechanisms involved during the increasing and decreasing portion of the pullback velocity as the peak shock stress is increased. [Preview Abstract] |
Monday, June 27, 2011 11:45AM - 12:00PM |
C1.00004: Expanding cylinder experiments in Cu-2wt{\%}Be Stewart Stirk, Ron Winter Expanding cylinder techniques are useful methods of investigating dynamic fracture properties since uniform radial strains are achieved at high strain-rates. A gas-gun technique to achieve uniform radial expansion of a cylinder is explored in which the motion of the cylinder is driven by impact of a plastic projectile upon silastomer rubber that partially fills the specimen cylinder. Cylinders of age-hardened copper-beryllium alloy Cu-2wt{\%}Be (TF00 treatment) have been expanded to failure at radial strain-rates in the range 1.2 - 5.7 $\times $10$^{3}$ s$^{-1}$. The temporal history of fracture activation is captured using high speed photography and modelled using a combined statistics and energy based fragmentation theory [1]. The model is shown to reproduce the crack dynamics and strain-rate dependence reasonably well.\\[4pt] [1] D. E. Grady, and M. L. Olsen, Int. J. Impact Engng. \textbf{29}, 293 (2003). [Preview Abstract] |
Monday, June 27, 2011 12:00PM - 12:15PM |
C1.00005: The Effect of Case Fracture on Blast Impulse Michael Hutchinson The initial velocity of casing fragments from bombs, shells etc. was first calculated by R.W. Gurney in 1943. This derivation was based on a reasonable simplification of the casing and gas dynamics. Subsequently, Gurney's wartime co- worker, U. Fano, issued a further report on the blast equivalence of cased explosive charges, i.e. the blast impulse they deliver as a fraction of the impulse from the same charge uncased. Fano claimed to have calculated the proportion of kinetic energy remaining with the explosive gases following energy partition with the casing. This presentation will show that Fano's equation for cased charge blast equivalence is inconsistent with Gurney's reasonable physical model, as is a further equation by Fisher. The presenter will draw attention to an equation recently published, which gives similar predictions to that of Fisher, while being consistent with Gurney's original derivation. Furthermore, it will be shown that Gurney's kinetic energy equation can be combined with G.I. Taylor's equation for case fracture strain to provide a casing-gas energy balance at fracture. This provides for the first time a widely applicable equation for the blast equivalence of cased charges, dependent only on the relative masses of the casing and explosive charge and their respective material or energetic properties. Bearing in mind possible experimental shortcomings, predictions are reasonably in accordance with blast impulse data so far available. [Preview Abstract] |
Monday, June 27, 2011 12:15PM - 12:30PM |
C1.00006: Spall strength of sapphire Andrey Savinykh, Gennady Kanel, Sergey Razorenov The spall strength of c-cut sapphire has been measured as a function of the load duration and peak stress. In experiments, the VISAR particle velocity histories at the interface between the sapphire samples and a water window were recorded. The peak shock stress varied from 17.3 GPa up to 21.4 GPa that is below the Hugoniot elastic limit but close to it, the load duration varied from 100-150 ns to 250-300 ns. Within this range measured values of the spall strength varies from 4.2 to 10.6 GPa. Results of measurements demonstrate much higher sensitivity of the spall strength to the strain rate than that for metals and a trend to its decrease with the increasing peak stress. Development of any inelastic deformation leads to complete loss of the resistance to tension in the domain of a sapphire sample where these processes occurred. The complex of experimental observations leads to conclusion that the damage nuclei may appear in sapphire under both uniaxial compression and following tension and the expectation time decreases with increasing both compressive and tensile stresses. [Preview Abstract] |
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