Bulletin of the American Physical Society
19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015; Tampa, Florida
Session J6: Inelastic Deformations, Fracture and Spall V: Extreme Loading |
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Chair: Cyril Williams, Army Research Laboratory, Gennady Kanel, Institute for High Temperatures RAS Room: 8/9/10 |
Tuesday, June 16, 2015 11:15AM - 11:30AM |
J6.00001: Analysis of laser-driven fragmentation experiments performed on Orion facility Laurent Videau, Jim Andrew, Jean-Marc Chevalier, Patrick Combis, Alain Galtie, Alain Geille, Jean-Paul Jadaud, Jean-Hugues Quessada, Didier Raffestin, Michael Rubery We present laser-driven fragmentation experiments performed on the Orion laser facility at AWE. The experimental campaign was divided in two parts. The first one was dedicated in characterizing of the debris and shrapnels emission coming from gold and aluminum cylinders. The second one was devoted to spall experiments with x-ray irradiated samples such as steel, tantalum, aluminum or PMMA. We used passive collectors and PDV diagnostics to analyze the matter ejection in both configurations. We have developed a complete 2D numeric tool including laser-matter interaction, shock propagation and spallation which allows us to simulate experiments. A comparison with experimental results will be presented. [Preview Abstract] |
Tuesday, June 16, 2015 11:30AM - 11:45AM |
J6.00002: Material characteristics for an analytic hypervelocity impact performance model Joshua Miller, Shannon Ryan A performance model has recently been developed to describe the evolution of a hypervelocity impact of a threat with a dual-wall, Whipple shield. The Whipple shield uses an initial sacrificial wall to initiate threat fragmentation and melt before the debris expands over a void and is subsequently arrested by the second wall in front of a critical component. As such, understanding the initial interaction of the threat particle and the sacrificial wall is crucial to modeling the overall shield performance. Among the key material parameters that must be defined for the threat particle and sacrificial wall are the equilibrium shock wave states and tensile response to vacuum exposure. This paper documents the work performed to obtain the necessary material characteristics and a description of the fragmentation of the threat needed for the performance model. The results from the use of these quantities within the model are compared here with hydrodynamic simulations and available experimental records that have sought to characterize these parameters. [Preview Abstract] |
Tuesday, June 16, 2015 11:45AM - 12:00PM |
J6.00003: The behavior of iron under ultrafast shock loading driven by a femtosecond laser Sergey Ashitkov, Vasily Zhakhovsky, Pavel Komarov, Nail Inogamov, Mikhail Agranat, Gennady Kanel The results of experimental and theoretical investigations of shock-wave propagation in bcc iron under ultra-short loads driven by femtosecond laser pulses are presented. Chirped pulse interferometry was used for continuous diagnostics of movement in a picosecond range of the rear-side surface of thin iron films. The evolution of ultra-short elastic-plastic shock waves in samples with different thicknesses and purity has been studied. The obtained HEL and spall strength are close to ultimate values of shear and tensile stresses. Response of single-crystal iron to ultra-short shock loading/unloading was also explored in micron-sized films by molecular dynamics simulations. The experimental and simulation results on shock-induced elastic-plastic transformation and phase transition from bcc to hcp iron in a picosecond range of loading are discussed. [Preview Abstract] |
Tuesday, June 16, 2015 12:00PM - 12:15PM |
J6.00004: Rarefaction after fast laser heating of thin metal film on a glass mount: spallation and inflation from one-dimensional to three-dimensional ablation flow Nail Inogamov, Viktor Khokhlov, Yury Petrov, Vasily Zhakhovsky, Kirill Migdal, Denis Ilnitsky, Noboru Hasegawa, Masaharu Nishikino, Mitsuru Yamagiwa, Masahiko Ishino, Tetsuya Kawachi, Anatoly Faenov, Tatiana Pikuz, Shintaro Takayoshi, Takashi Eyama, Naoya Kakimoto, Takuro Tomita, Motoyoshi Baba, Yasuo Minami, Tohru Suemoto We numerically and experimentally consider the effect of subpicosecond Ti:sapp laser pump pulse onto 60-100 nm silver and gold films mounted onto a silica substrate. Pump pulse spalls out the film from the substrate. Influence of diameter of a laser irradiated spot 1-100 microns on a film surface is studied. A cupola like spallation shell is flying from the substrate. For the large spot the soft X-ray probe laser is used for measuring the ablation process. The research (NAI, VVZh, VAKh, DKI, YVP, KPM, AYF, TAP) has been performed under financial support from Russian Science Foundation (RSCF) (project No. 14-19-01599). [Preview Abstract] |
Tuesday, June 16, 2015 12:15PM - 12:45PM |
J6.00005: Plastic Deformation, Amorphization, and Phase Changes in Extreme Laser Shock Compression of Ta and Si Invited Speaker: Marc Meyers High-amplitude pulsed lasers probe the response of materials at pressures up to 100s of GPa and strain rates of 10$^{\mathrm{8}}$ s$^{\mathrm{-1}}$, revealing plastic deformation, phase transformations, and amorphization. Molecular dynamics simulations provide modeling at comparable strain rates and time durations. Shock compression of monocrystalline Ta reveals dislocations at low pressures and twinning at higher pressures (above 24 GPa). Results are compared with predictions from homogeneous dislocation generation and multiplication and the latter mechanism is dominant. The formation of an Omega phase was observed in monocrystalline tantalum at a shock amplitude of approximately 70 GPa. The shear stresses may play a role in the transformation. As shock energy increases, the following structural changes in monocrystalline Si are observed: dislocations and stacking faults; bands of amorphized Si forming on crystallographic orientations consistent with slip; broad regions of amorphized Si; nanocrystalline Si resulting from re-crystallization. MD simulations display similar amorphous regions. Funding: UCOP and DOE SSAP. [Preview Abstract] |
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