Insider Threat Mitigation Workshop Instructional Materials

Energy Technology Data Exchange (ETDEWEB)

Gibbs, Philip [Brookhaven National Lab. (BNL), Upton, NY (United States); Larsen, Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); O' Brien, Mike [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rodriquez, Jose [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2008-01-01

Insiders represent a formidable threat to nuclear facilities. This set of workshop materials covers methodologies to analyze and approaches to mitigate the threat of an insider attempting abrupt theft of nuclear materials. This report is a compilation of workshop materials consisting of lectures on technical and administrative measures used in Physical Protection (PP) and Material Control and Accounting (MC&A) and methods for analyzing their effectiveness against a postulated insider threat.

Ultrafast dynamic ellipsometry and spectroscopies of laser shocked materials

Energy Technology Data Exchange (ETDEWEB)

Mcgrane, Shawn David [Los Alamos National Laboratory; Bolme, Cindy B [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory

2010-01-01

Ultrafast ellipsometry and transient absorption spectroscopies are used to measure material dynamics under extreme conditions of temperature, pressure, and volumetric compression induced by shock wave loading with a chirped, spectrally clipped shock drive pulse.

Simulation Study of Shock Reaction on Porous Material

International Nuclear Information System (INIS)

Xu Aiguo; Zhang Guangcai; Pan Xiaofei; Zhu Jianshi

2009-01-01

Direct modeling of porous materials under shock is a complex issue. We investigate such a system via the newly developed material-point method. The effects of shock strength and porosity size are the main concerns. For the same porosity, the effects of mean-void-size are checked. It is found that local turbulence mixing and volume dissipation are two important mechanisms for transformation of kinetic energy to heat. When the porosity is very small, the shocked portion may arrive at a dynamical steady state; the voids in the downstream portion reflect back rarefactive waves and result in slight oscillations of mean density and pressure; for the same value of porosity, a larger mean-void-size makes a higher mean temperature. When the porosity becomes large, hydrodynamic quantities vary with time during the whole shock-loading procedure: after the initial stage, the mean density and pressure decrease, but the temperature increases with a higher rate. The distributions of local density, pressure, temperature and particle-velocity are generally non-Gaussian and vary with time. The changing rates depend on the porosity value, mean-void-size and shock strength. The stronger the loaded shock, the stronger the porosity effects. This work provides a supplement to experiments for the very quick procedures and reveals more fundamental mechanisms in energy and momentum transportation. (general)

Shock-induced synthesis of high temperature superconducting materials

Science.gov (United States)

Ginley, D.S.; Graham, R.A.; Morosin, B.; Venturini, E.L.

1987-06-18

It has now been determined that the unique features of the high pressure shock method, especially the shock-induced chemical synthesis technique, are fully applicable to high temperature superconducting materials. Extraordinarily high yields are achievable in accordance with this invention, e.g., generally in the range from about 20% to about 99%, often in the range from about 50% to about 90%, lower and higher yields, of course, also being possible. The method of this invention involves the application of a controlled high pressure shock compression pulse which can be produced in any conventional manner, e.g., by detonation of a high explosive material, the impact of a high speed projectile or the effect of intense pulsed radiation sources such as lasers or electron beams. Examples and a discussion are presented.

Propagation and dispersion of shock waves in magnetoelastic materials

Science.gov (United States)

Crum, R. S.; Domann, J. P.; Carman, G. P.; Gupta, V.

2017-12-01

Previous studies examining the response of magnetoelastic materials to shock waves have predominantly focused on applications involving pulsed power generation, with limited attention given to the actual wave propagation characteristics. This study provides detailed magnetic and mechanical measurements of magnetoelastic shock wave propagation and dispersion. Laser generated rarefacted shock waves exceeding 3 GPa with rise times of 10 ns were introduced to samples of the magnetoelastic material Galfenol. The resulting mechanical measurements reveal the evolution of the shock into a compressive acoustic front with lateral release waves. Importantly, the wave continues to disperse even after it has decayed into an acoustic wave, due in large part to magnetoelastic coupling. The magnetic data reveal predominantly shear wave mediated magnetoelastic coupling, and were also used to noninvasively measure the wave speed. The external magnetic field controlled a 30% increase in wave propagation speed, attributed to a 70% increase in average stiffness. Finally, magnetic signals propagating along the sample over 20× faster than the mechanical wave were measured, indicating these materials can act as passive antennas that transmit information in response to mechanical stimuli.

Shock wave equation of state of powder material

OpenAIRE

Dijken, D.K.; Hosson, J.Th.M. De

1994-01-01

A model is proposed to predict the following quantities for powder materials compacted by shock waves: the pressure, the specific volume, the internal energy behind the shock wave, and the shock-wave velocity U-s. They are calculated as a function of flyerplate velocity u(p) and initial powder specific volume V-00. The model is tested on Cu, Al2024, and Fe. Calculated U-s vs u(p) curves agree well with experiments provided V-00 is smaller than about two times the solid specific volume. The mo...

Advanced insider threat mitigation workshop instructional materials

Energy Technology Data Exchange (ETDEWEB)

Gibbs, Philip [Brookhaven National Lab. (BNL), Upton, NY (United States); Larsen, Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); O Brien, Mike [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Edmunds, Tom [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2008-11-01

Insiders represent a formidable threat to nuclear facilities. This set of workshop materials covers methodologies to analyze and approaches to mitigate the threat of an insider attempting abrupt and protracted theft of nuclear materials. This particular set of materials is a n update of a January 2008 version to add increased emphasis on Material Control and Accounting and its role with respect to protracted insider nuclear material theft scenarios.

Development of a General Shocked-Materials-Response Description for Simulations

Energy Technology Data Exchange (ETDEWEB)

Steven M. Valone

2000-07-01

This report outlines broad modeling issues pertaining to polymeric materials behavior under detonation conditions. Models applicable system wide are necessary to cope with the broad range of polymers and complex composite forms that can appear in Laboratory weapons systems. Nine major topics are discussed to span the breadth of materials, forms, and physical phenomena encountered when shocking polymers and foams over wide ranges of temperatures, pressures, shock strengths, confinement conditions, and geometries. The recommendations for directions of more intensive investigation consider physical fidelity, computational complexity, and application over widely varying physical conditions of temperature, pressure, and shock strength.

Laser-shocked energetic materials with metal additives: evaluation of detonation performance

Science.gov (United States)

Gottfried, Jennifer; Bukowski, Eric

A focused, nanosecond-pulsed laser with sufficient energy to exceed the breakdown threshold of a material generates a laser-induced plasma with high peak temperatures, pressures, and shock velocities. Depending on the laser parameters and material properties, nanograms to micrograms of material is ablated, atomized, ionized and excited in the laser-induced plasma. The subsequent shock wave expansion into the air above the sample has been monitored using high-speed schlieren imaging in a recently developed technique, laser-induced air shock from energetic materials (LASEM). The estimated detonation velocities using LASEM agree well with published experimental values. A comparison of the measured shock velocities for various energetic materials including RDX, DNTF, and LLM-172 doped with Al or B to the detonation velocities predicted by CHEETAH for inert or active metal participation demonstrates that LASEM has potential for predicting the early time participation of metal additives in detonation events. The LASEM results show that reducing the amount of hydrogen present in B formulations increases the resulting detonation velocities

A bi-annular-gap magnetorheological energy absorber for shock and vibration mitigation

Science.gov (United States)

Bai, Xian-Xu; Wereley, Norman M.; Choi, Young-Tai; Wang, Dai-Hua

2012-04-01

For semi-active shock and vibration mitigation systems using magnetorheological energy absorbers (MREAs), the minimization of the field-off damper force of the MREA at high speed is of particular significance because the damper force due to the viscous damping at high speed becomes too excessive and thus the controllable dynamic force range that is defined by the ratio of the field-on damper force to the field-off damper force is significantly reduced. In this paper, a bi-annular-gap MREA with an inner-set permanent magnet is proposed to decrease the field-off damper force at high speed while keeping appropriate dynamic force range for improving shock and vibration mitigation performance. In the bi-annular-gap MREA, two concentric annular gaps are configured in parallel so as to decrease the baseline damper force and both magnetic activation methods using the electromagnetic coil winding and the permanent magnet are used to keep holding appropriate magnetic intensity in these two concentric annular gaps in the consideration of failure of the electric power supply. An initial field-on damper force is produced by the magnetic field bias generated from the inner-set permanent magnet. The initial damper force of the MREA can be increased (or decreased) through applying positive (or negative) current to the electromagnetic coil winding inside the bi-annular-gap MREA. After establishing the analytical damper force model of the bi-annular-gap MREA using a Bingham-plastic nonlinear fluid model, the principle and magnetic properties of the MREA are analytically validated and analyzed via electromagnetic finite element analysis (FEA). The performance of the bi-annular-gap MREA is also theoretically compared with that of a traditional single-annular- gap MREA with the constraints of an identical volume by the performance matrix, such as the damper force, dynamic force range, and Bingham number with respect to different excitation velocities.

Evaluation of thermal shock strengths for graphite materials using a laser irradiation method

International Nuclear Information System (INIS)

Kim, Jae Hoon; Lee, Young Shin; Kim, Duck Hoi; Park, No Seok; Suh, Jeong; Kim, Jeng O.; Il Moon, Soon

2004-01-01

Thermal shock is a physical phenomenon that occurs during the exposure to rapidly high temperature and pressure changes or during quenching of a material. The rocket nozzle throat is exposed to combustion gas of high temperature. Therefore, it is important to select suitable materials having the appropriate thermal shock resistance and to evaluate these materials for rocket nozzle design. The material of this study is ATJ graphite, which is the candidate material for rocket nozzle throat. This study presents an experimental method to evaluate the thermal shock resistance and thermal shock fracture toughness of ATJ graphite using laser irradiation. In particular, thermal shock resistance tests are conducted with changes of specimen thickness, with laser source irradiated at the center of the specimen. Temperature distributions on the specimen surface are detected using type K and C thermocouples. Scanning electron microscope (SEM) is used to observe the thermal cracks on specimen surface

Thermal shock behaviour of mullite-cordierite refractory materials

Czech Academy of Sciences Publication Activity Database

Boccaccini, D. N.; Leonelli, C.; Romagnoli, M.; Pellacani, G. C.; Veronesi, P.; Dlouhý, Ivo; Boccaccini, A. R.

2007-01-01

Roč. 106, č. 3 (2007), s. 142-148 ISSN 1743-6753 R&D Projects: GA AV ČR IAA200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : refraktory materials * thermal shock * fracutre toughness Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.074, year: 2007

Correlation of physical properties of ceramic materials with resistance to fracture by thermal shock

Science.gov (United States)

Lidman, W G; Bobrowsky, A R

1949-01-01

An analysis is made to determine which properties of materials affect their resistance to fracture by thermal stresses.From this analysis, a parameter is evaluated that is correlated with the resistance of ceramic materials to fracture by thermal shock as experimentally determined. This parameter may be used to predict qualitatively the resistance of a material to fracture by thermal shock. Resistance to fracture by thermal shock is shown to be dependent upon the following material properties: thermal conductivity, tensile strength, thermal expansion, and ductility modulus. For qualitative prediction of resistance of materials to fracture by thermal shock, the parameter may be expressed as the product of thermal conductivity and tensile strength divided by the product of linear coefficient of thermal expansion and ductility modulus of the specimen.

Nano-material aspects of shock absorption in bone joints.

Science.gov (United States)

Tributsch, H; Copf, F; Copf, P; Hindenlang, U; Niethard, F U; Schneider, R

2010-01-01

This theoretical study is based on a nano-technological evaluation of the effect of pressure on the composite bone fine structure. It turned out, that the well known macroscopic mechano-elastic performance of bones in combination with muscles and tendons is just one functional aspect which is critically supported by additional micro- and nano- shock damping technology aimed at minimising local bone material damage within the joints and supporting spongy bone material. The identified mechanisms comprise essentially three phenomena localised within the three-dimensional spongy structure with channels and so called perforated flexible tensulae membranes of different dimensions intersecting and linking them. Kinetic energy of a mechanical shock may be dissipated within the solid-liquid composite bone structure into heat via the generation of quasi-chaotic hydromechanic micro-turbulence. It may generate electro-kinetic energy in terms of electric currents and potentials. And the resulting specific structural and surface electrochemical changes may induce the compressible intra-osseal liquid to build up pressure dependent free chemical energy. Innovative bone joint prostheses will have to consider and to be adapted to the nano-material aspects of shock absorption in the operated bones.

Thermal shock resistances of a bonding material of C/C composite and copper

International Nuclear Information System (INIS)

Kurumada, Akira; Oku, Tatsuo; Kawamata, Kiyohiro; Motojima, Osamu; Noda, Nobuaki; McEnaney, B.

1997-01-01

The purpose of this study is to contribute to the development and the safety design of plasma facing components for fusion reactor devices. We evaluated the thermal shock resistance and the thermal shock fracture toughness of a bonding material which was jointed a carbon-fiber-reinforced carbon composite (C/C composite) to oxygen-free copper. We also examined the microstructures of the bonding layers using a scanning electron microscope before and after thermal shock tests. The bonding material did not fracture during thermal shock tests. However, thermal cracks and delamination cracks were observed in the bonding layers. (author)

Precise optical observation of 0.5-GPa shock waves in condensed materials

Science.gov (United States)

Nagayama, Kunihito; Mori, Yasuhito

1999-06-01

Precision optical observation method was developed to study impact-generated high-pressure shock waves in condensed materials. The present method makes it possible to sensitively detect the shock waves of the relatively low shock stress around 0.5 GPa. The principle of the present method is based on the use of total internal reflection by triangular prisms placed on the free surface of a target assembly. When a plane shock wave arrives at the free surface, the light reflected from the prisms extinguishes instantaneously. The reason is that the total internal reflection changes to the reflection depending on micron roughness of the free surface after the shock arrival. The shock arrival at the bottom face of the prisms can be detected here by two kinds of methods, i.e., a photographic method and a gauge method. The photographic method is an inclined prism method of using a high-speed streak camera. The shock velocity and the shock tilt angle can be estimated accurately from an obtained streak photograph. While in the gauge method, an in-material PVDF stress gauge is combined with an optical prism-pin. The PVDF gauge records electrically the stress profile behind the shockwave front, and the Hugoniot data can be precisely measured by combining the prism pin with the PVDF gauge.

Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials

Energy Technology Data Exchange (ETDEWEB)

Mcgrane, Shawn David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bolme, Cindy B [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Whitley, Von H [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moore, David S [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2010-01-01

Shock waves create extreme states of matter with very high pressures, temperatures, and volumetric compressions, at an exceedingly rapid rate of change. We review how to use a beamsplitter and a note card to turn a typical chirp pulse amplified femtosecond laser system into an ultrafast shock dynamics machine. Open scientific questions that can be addressed with such an apparatus are described. We report on the development of several single shot time resolved diagnostics needed to answer these questions. These single shot diagnostics are expected to be broadly applicable to other types of laser ablation experiments. Experimental results measured from shocked material dynamics of several systems are detailed. Finally, we report on progress towards using transient absorption as a measure of electronic excitation and coherent Raman as a picosecond probe of temperature in shock compressed condensed matter.

High-energy synchrotron X-ray radiography of shock-compressed materials

Science.gov (United States)

Rutherford, Michael E.; Chapman, David J.; Collinson, Mark A.; Jones, David R.; Music, Jasmina; Stafford, Samuel J. P.; Tear, Gareth R.; White, Thomas G.; Winters, John B. R.; Drakopoulos, Michael; Eakins, Daniel E.

2015-06-01

This presentation will discuss the development and application of a high-energy (50 to 250 keV) synchrotron X-ray imaging method to study shock-compressed, high-Z samples at Beamline I12 at the Diamond Light Source synchrotron (Rutherford-Appleton Laboratory, UK). Shock waves are driven into materials using a portable, single-stage gas gun designed by the Institute of Shock Physics. Following plate impact, material deformation is probed in-situ by white-beam X-ray radiography and complimentary velocimetry diagnostics. The high energies, large beam size (13 x 13 mm), and appreciable sample volumes (~ 1 cm3) viable for study at Beamline I12 compliment existing in-house pulsed X-ray capabilities and studies at the Dynamic Compression Sector. The authors gratefully acknowledge the ongoing support of Imperial College London, EPSRC, STFC and the Diamond Light Source, and AWE Plc.

Dynamical Effects in Metal-Organic Frameworks: The Microporous Materials as Shock Absorbers

Science.gov (United States)

Banlusan, Kiettipong; Strachan, Alejandro

2017-06-01

Metal-organic frameworks (MOFs) are a class of nano-porous crystalline solids consisting of inorganic units coordinated to organic linkers. The unique molecular structures and outstanding properties with ultra-high porosity and tunable chemical functionality by various choices of metal clusters and organic ligands make this class of materials attractive for many applications. The complex and quite unique responses of these materials to mechanical loading including void collapse make them attractive for applications in energy absorption and storage. We will present using large-scale molecular dynamics simulations to investigate shock propagation in zeolitic imidazolate framework ZIF-8 and MOF-5. We find that for shock strengths above a threshold a two-wave structure develops with a leading elastic precursor followed by a second wave of structural collapse to relax the stress. Structural transition of MOFs in response to shock waves corresponds to the transition between two Hugoniot curves, and results in abrupt change in temperature. The pore-collapse wave propagates at slower velocity than the leading wave and weakens it, resulting in shock attenuation. Increasing piston speed results in faster propagation of pore-collapse wave, but the leading elastic wave remains unchanged below the overdriven regime. We discuss how the molecular structure of the MOFs and shock propagation direction affect the response of the materials and their ability to weaken shocks. Office of Naval Research, MURI 2012 02341 01.

Meso-scale modelling of the heat conductivity effect on the shock response of a porous material

Science.gov (United States)

Resnyansky, A. D.

2017-06-01

Understanding of deformation mechanisms of porous materials under shock compression is important for tailoring material properties at the shock manufacturing of advanced materials from substrate powders and for studying the response of porous materials under shock loading. Numerical set-up of the present work considers a set of solid particles separated by air representing a volume of porous material. Condensed material in the meso-scale set-up is simulated with a viscoelastic rate sensitive material model with heat conduction formulated from the principles of irreversible thermodynamics. The model is implemented in the CTH shock physics code. The meso-scale CTH simulation of the shock loading of the representative volume reveals the mechanism of pore collapse and shows in detail the transition from a high porosity case typical for abnormal Hugoniot response to a moderate porosity case typical for conventional Hugoniot response. Results of the analysis agree with previous analytical considerations and support hypotheses used in the two-phase approach.

Transport and Reactivity of Decontaminants to Provide Hazard Mitigation of Chemical Warfare Agents from Materials

Science.gov (United States)

2016-06-01

2013 4. TITLE AND SUBTITLE Transport and Reactivity of Decontaminants to Provide Hazard Mitigation of Chemical Warfare Agents from Materials 5a...directions for future decontamination formulation approaches. 15. SUBJECT TERMS GD HD Decontamination Hazard mitigation VX Chemical warfare agent... DECONTAMINANTS TO PROVIDE HAZARD MITIGATION OF CHEMICAL WARFARE AGENTS FROM MATERIALS 1. INTRODUCTION Decontamination of materials is the

Experimental and Theoretical Investigation of Shock-Induced Reactions in Energetic Materials

Energy Technology Data Exchange (ETDEWEB)

Kay, Jeffrey J. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Park, Samuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kohl, Ian Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knepper, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Farrow, Darcie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tappan, Alexander S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-09-01

In this work, shock-induced reactions in high explosives and their chemical mechanisms were investigated using state-of-the-art experimental and theoretical techniques. Experimentally, ultrafast shock interrogation (USI, an ultrafast interferometry technique) and ultrafast absorption spectroscopy were used to interrogate shock compression and initiation of reaction on the picosecond timescale. The experiments yielded important new data that appear to indicate reaction of high explosives on the timescale of tens of picoseconds in response to shock compression, potentially setting new upper limits on the timescale of reaction. Theoretically, chemical mechanisms of shock-induced reactions were investigated using density functional theory. The calculations generated important insights regarding the ability of several hypothesized mechanisms to account for shock-induced reactions in explosive materials. The results of this work constitute significant advances in our understanding of the fundamental chemical reaction mechanisms that control explosive sensitivity and initiation of detonation.

The shock tube as wave reactor for kinetic studies and material systems

Energy Technology Data Exchange (ETDEWEB)

Bhaskaran, K.A. [Indian Institute of Technology, Chennai (India). Department of Mechanical Engineering; Roth, P. [Gerhard Mercator Universitat, Duisberg (Germany). Institut fur Verbrennung und Gasdynamik

2002-07-01

Several important reviews of shock tube kinetics have appeared earlier, prominent among them being 'Shock Tube Technique in Chemical Kinetics' by Belford and Strehlow (Ann Rev Phys Chem 20 (1969) 247), 'Chemical Reaction of Shock Waves' by Wagner (Proceedings of the Eighth International Shock Tube Symposium (1971) 4/1), 'Shock Tube and Shock Wave Research' by Bauer and Lewis (Proceedings of the 11th International Symposium on Shock Tubes and Waves (1977) 269), 'Shock Waves in Chemistry' edited by Assa Lifshitz (Shock Waves in Chemistry, 1981) and 'Shock Tube Techniques in Chemical Kinetics' by Wing Tsang and Assa Lifshitz (Annu Rev Phys Chem 41 (1990) 559). A critical analysis of the different shock tube techniques, their limitations and suggestions to improve the accuracy of the data produced are contained in these reviews. The purpose of this article is to present the current status of kinetic research with emphasis on the diagnostic techniques. Selected studies on homogeneous and dispersed systems are presented to bring out the versatility of the shock tube technique. The use of the shock tube as high temperature wave reactor for gas phase material synthesis is also highlighted. (author)

Can superabsorbent polymers mitigate shrinkage in cementitious materials blended with supplementary cementitious materials?

DEFF Research Database (Denmark)

Snoeck, Didier; Jensen, Ole Mejlhede; De Belie, Nele

2016-01-01

A promising way to mitigate autogenous shrinkage in cementitious materials with a low water-to-binder ratio is internal curing by the use of superabsorbent polymers. Superabsorbent polymers are able to absorb multiple times their weight in water and can be applied as an internal water reservoir...... to induce internal curing and mitigation of self-desiccation. Their purposefulness has been demonstrated in Portland cement pastes with and without silica fume. Nowadays, fly ash and blast-furnace slag containing binders are also frequently used in the construction industry. The results on autogenous...... shrinkage in materials blended with fly ash or blast-furnace slag remain scarce, especially after one week of age. This paper focuses on the autogenous shrinkage by performing manual and automated shrinkage measurements up to one month of age. Without superabsorbent polymers, autogenous shrinkage...

Self-consistent technique for estimating the dynamic yield strength of a shock-loaded material

International Nuclear Information System (INIS)

Asay, J.R.; Lipkin, J.

1978-01-01

A technique is described for estimating the dynamic yield stress in a shocked material. This method employs reloading and unloading data from a shocked state along with a general assumption of yield and hardening behavior to estimate the yield stress in the precompressed state. No other data are necessary for this evaluation, and, therefore, the method has general applicability at high shock pressures and in materials undergoing phase transitions. In some special cases, it is also possible to estimate the complete state of stress in a shocked state. Using this method, the dynamic yield strength of aluminum at 2.06 GPa has been estimated to be 0.26 GPa. This value agrees reasonably well with previous estimates

Advanced Insider Threat Mitigation Workshop Instructional Materials

Energy Technology Data Exchange (ETDEWEB)

Gibbs, Philip [Brookhaven National Lab. (BNL), Upton, NY (United States); Larsen, Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); O' Brien, Mike [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Edmunds, Tom [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2009-02-01

Insiders represent a formidable threat to nuclear facilities. This set of workshop materials covers methodologies to analyze and approaches to mitigate the threat of an insider attempting abrupt and protracted theft of nuclear materials. This particular set of materials is an update of a January 2008 version to add increased emphasis on Material Control and Accounting and its role with respect to protracted insider nuclear material theft scenarios. This report is a compilation of workshop materials consisting of lectures on technical and administrative measures used in Physical Protection (PP) and Material Control and Accounting (MC&A) and methods for analyzing their effectiveness against a postulated insider threat. The postulated threat includes both abrupt and protracted theft scenarios. Presentation is envisioned to be through classroom instruction and discussion. Several practical and group exercises are included for demonstration and application of the analysis approach contained in the lecture/discussion sessions as applied to a hypothetical nuclear facility.

A Comparative Study of the Behaviour of Five Dense Glass Materials Under Shock Loading Conditions

Science.gov (United States)

Radford, Darren D.; Proud, William G.; Field, John E.

2001-06-01

Previous work at the Cavendish Laboratory on the properties of glasses under shock loading has demonstrated that the material response is highly dependent upon the composition of the glass. The shock response of glass materials with an open structure, such as borosilicate, exhibits a ramping behaviour in the longitudinal stress histories due to structural collapse. Glass materials with a “filled” microstructure, as in the case of Type-D, Extra Dense Flint (DEDF) do not exhibit a ramping behaviour and behave in a manner similar to polycrystalline ceramics [1]. The current investigation compares the behaviour of five such glasses (SF15, DEDF, LACA, SF57 and DEDF-927210) under shock loading conditions. It is observed that slight changes in material composition can have a large affect on the inelastic behaviour. Principal Hugoniot and shear strength data are presented for all of the materials for pressures ranging from 2 to 14 GPa. Evidence of the so-called failure-front [2] is presented via lateral stress histories measured using manganin stress gauges and confirmed with high-speed photography. 1. Bourne, N.K., Millett, J.C.F., and Field, J.E., “On the strength of shocked glasses” Proc. R. Soc. Lond. A 455 (1999) 1275-1282 2. Brar, N.S., “Failure Waves in Glass and Ceramics Under Shock Compression”, in "Shock Compression of Condensed Matter 1999", ed. M.D. Furnish, L.C. Chhabildas, and R.S. Hixson, American Institute of Physics, Woodbury, New York, (1999) 601-606

Macroeconomic impacts of oil price shocks in Asian economies

International Nuclear Information System (INIS)

Cunado, Juncal; Jo, Soojin; Perez de Gracia, Fernando

2015-01-01

This paper analyzes the macroeconomic impact of structural oil shocks in four of the top oil-consuming Asian economies, using a VAR model. We identify three different structural oil shocks via sign restrictions: an oil supply shock, an oil demand shock driven by global economic activity and an oil-specific demand shock. The main results suggest that economic activity and prices respond very differently to oil price shocks depending on their types. In particular, an oil supply shock has a limited impact, while a demand shock driven by global economic activity has a significant positive effect in all four Asian countries examined. Our finding also includes that policy tools such as interest rates and exchange rates help mitigating the effects of supply shocks in Japan and Korea; however, they can be more actively used in response to demands shocks. - Highlights: • We analyze the effects of three structural oil price shocks on Asian economies. • Supply shocks have limited impact on the economic activity of Asian economies examined. • Demand shocks due to economic activity boosts GDP of all economies. • CPIs in India and Indonesia were only marginally affected by oil price shocks. • Monetary and exchange rate tools help mitigating supply shocks in Korea and Japan.

Material Evidence for Ocean Impact from Shock-Metamorphic Experiments

Science.gov (United States)

Miura, Y.; Takayama, K.; Iancu, O. G.

1993-07-01

Continental impact reveals an excavated crater that has few fresh fine ejecta showing major high shock metamorphism due to weathering [1]. A giant ocean impact rarely remains as an excavated crater mainly due to crushing by dynamic plate-tectonic movements on the crust [2]. However, all impact materials, including fine-grained ejecta, can be obtained with artificial impact experiments [3]. The purpose of this study is to discuss material evidence for ocean impact based on shock-metamorphic experiments. Artificial impact experiments indicate that fine shocked quartz (SQ) aggregates can be formed on several target rocks (Table 1) [1]. It is found in Table 1 that (1) the largest-density deviation of SQ grain is found not at the wall-rock or the impact crater but at fine-grained ejecta, and (2) silica-poor rocks of basalt, gabbro, and anorthosite can also make fine SQ aggregates by impact. Table 1, which appears here in the hard copy, shows formations of fine shocked quartz aggregates from ocean-floor rocks of basalt, gabbroic anorthosite, and granite [3]. An asteroid (about 10 km across) hits the Earth ~65 m.y. ago [4] to result in global catastrophe by titanic explosion and climate change. But shocked quartz grains found in the K/T boundary layer were considered to come from crystalline continental rocks [5]. The present result as listed in Table 1 indicates that fine SQ aggregates can also be formed at sea-floor basaltic and gabbroic rocks [3]. The present result of formation of the SQ grains from sea- floor target rocks is nearly consistent with the finding of a sea-impact crater at the K/T boundary near the Caribbean [6]. Impact-induced volcanism at the K/T boundary can explained by the penetration from thin ocean crust to upper mantle reservoirs, if giant impact of a 10-km- diameter asteroid hit the ocean [2,7]. The present result can explain "phreatomagmatic (magmatic vapor) explosion," which is created by abrupt boiling between high-temperature magma and cold

Shock-Driven Hydrodynamic Instability Growth Near Phase Boundaries and Material Property Transitions: Final Report

Energy Technology Data Exchange (ETDEWEB)

Peralta, Pedro [Arizona State Univ., Tempe, AZ (United States); Fortin, Elizabeth [Arizona State Univ., Tempe, AZ (United States); Opie, Saul [Arizona State Univ., Tempe, AZ (United States); Gautam, Sudrishti [Arizona State Univ., Tempe, AZ (United States); Gopalakrishnan, Ashish [Arizona State Univ., Tempe, AZ (United States); Lynch, Jenna [Arizona State Univ., Tempe, AZ (United States); Chen, Yan [Arizona State Univ., Tempe, AZ (United States); Loomis, Eric [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-03-01

Activities for this grant included: 1) Development of dynamic impact experiments to probe strength and phase transition influence on dynamic deformation, 2) development of modern strength and phase aware simulation capabilities, 3) and post-processing of experimental data with simulation and closed form analytical techniques. Two different dynamic experiments were developed to probe material strengths in solid metals (largely copper and iron in this effort). In the first experiment a flyer plate impacts a flat target with an opposite rippled surface that is partially supported by a weaker window material. Post mortem analysis of the target sample showed a strong and repeatable residual plastic deformation dependence on grain orientation. Yield strengths for strain rates near 10⁵ s^-1 and plastic strains near ~50% were estimated to be around 180 to 240 MPa, varying in this range with grain orientation. Unfortunately dynamic real-time measurements were difficult with this setup due to diagnostic laser scattering; hence, an additional experimental setup was developed to complement these results. In the second set of experiments a rippled surface was ablated by a controlled laser pulsed, which launched a rippled shock front to an opposite initially flat diagnostic surface that was monitored in real-time with spatially resolved velocimetry techniques, e.g., line VISAR in addition to Transient Imaging Displacement Interferometry (TIDI) displacement measurements. This setup limited the displacements at the diagnostic surface to a reasonable level for TIDI measurements (~ less than one micrometer). These experiments coupled with analytical and numerical solutions provided evidence that viscous and elastic deviatoric strength affect shock front perturbation evolution in clearly different ways. Particularly, normalized shock front perturbation amplitudes evolve with viscosity (η) and perturbation wavelength (λ) as η/λ, such that increasing viscosity

Investigation of Lithium Metal Hydride Materials for Mitigation of Deep Space Radiation

Science.gov (United States)

Rojdev, Kristina; Atwell, William

2016-01-01

Radiation exposure to crew, electronics, and non-metallic materials is one of many concerns with long-term, deep space travel. Mitigating this exposure is approached via a multi-faceted methodology focusing on multi-functional materials, vehicle configuration, and operational or mission constraints. In this set of research, we are focusing on new multi-functional materials that may have advantages over traditional shielding materials, such as polyethylene. Metal hydride materials are of particular interest for deep space radiation shielding due to their ability to store hydrogen, a low-Z material known to be an excellent radiation mitigator and a potential fuel source. We have previously investigated 41 different metal hydrides for their radiation mitigation potential. Of these metal hydrides, we found a set of lithium hydrides to be of particular interest due to their excellent shielding of galactic cosmic radiation. Given these results, we will continue our investigation of lithium hydrides by expanding our data set to include dose equivalent and to further understand why these materials outperformed polyethylene in a heavy ion environment. For this study, we used HZETRN 2010, a one-dimensional transport code developed by NASA Langley Research Center, to simulate radiation transport through the lithium hydrides. We focused on the 1977 solar minimum Galactic Cosmic Radiation environment and thicknesses of 1, 5, 10, 20, 30, 50, and 100 g/cm2 to stay consistent with our previous studies. The details of this work and the subsequent results will be discussed in this paper.

Drop Weight Device Fabrication and Tests for a Dynamic Material Property of Shock-Absorbing Material and Structure in Transportation Package

International Nuclear Information System (INIS)

Choi, Woo Seok; Jeon, Jea Eon; Han, Sang Hyeok; Lee, Sang Hoon; Seo, Ki Seok

2009-01-01

A radioactive material transportation package consists of canister and impact limiters. IAEA Safety Standard Series No. TS-R-1 recommends a drop test to evaluate the structural integrity of a transportation package under a hypothetical accident condition. The free drop test of a transportation package from 9 m height simulates one of accident conditions. The transportation package has a potential energy corresponding to 9 m drop height, and this energy changes to a kinetic energy when it impacts on the target. The energy is absorbed by a deformation of shock-absorbing material so that the minimum energy is transferred to canister. Accordingly, the shock-absorbing material is a very important part in transportation package design. Since the data for shock-absorbing material characteristics is acquired by a static test in general, it is quite different to that of dynamic characteristics. And the dynamic characteristics data is hardly found in literature. In this study, a drop weight facility was designed and fabricated which produces an impact speed like that of free drop of 9 m height. Several materials considered for an impact limiter and impact limiter structures were tested by a drop weight facility to acquire a dynamic material characteristics data

Drop Weight Device Fabrication and Tests for a Dynamic Material Property of Shock-Absorbing Material and Structure in Transportation Package

Energy Technology Data Exchange (ETDEWEB)

Choi, Woo Seok; Jeon, Jea Eon; Han, Sang Hyeok; Lee, Sang Hoon; Seo, Ki Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-05-15

A radioactive material transportation package consists of canister and impact limiters. IAEA Safety Standard Series No. TS-R-1 recommends a drop test to evaluate the structural integrity of a transportation package under a hypothetical accident condition. The free drop test of a transportation package from 9 m height simulates one of accident conditions. The transportation package has a potential energy corresponding to 9 m drop height, and this energy changes to a kinetic energy when it impacts on the target. The energy is absorbed by a deformation of shock-absorbing material so that the minimum energy is transferred to canister. Accordingly, the shock-absorbing material is a very important part in transportation package design. Since the data for shock-absorbing material characteristics is acquired by a static test in general, it is quite different to that of dynamic characteristics. And the dynamic characteristics data is hardly found in literature. In this study, a drop weight facility was designed and fabricated which produces an impact speed like that of free drop of 9 m height. Several materials considered for an impact limiter and impact limiter structures were tested by a drop weight facility to acquire a dynamic material characteristics data.

Idiosyncratic Shocks, Child Labor and School Attendance in Indonesia

Science.gov (United States)

Kharisma, Bayu

2017-01-01

This paper investigates the effect of various idiosyncratic shocks against child labor, child labor hour and school attendance. Also, the role of the assets held by households as one of the coping strategies to mitigate the effects of shocks. The results show that various idiosyncratic shocks that encourage child labor is generally caused by crop…

Fracture-mechanics data deduced from thermal-shock and related experiments with LWR pressure-vessel material

International Nuclear Information System (INIS)

Cheverton, R.D.; Canonico, D.A.; Iskander, S.K.; Bolt, S.E.; Holz, P.P.; Nanstad, R.K.; Stelzman, W.J.

1982-01-01

Pressurized water reactors (PWRs) are susceptible to certain types of hypothetical accidents that can subject the reactor pressure vessel to severe thermal shock, that is, a rapid cooling of the inner surface of the vessel wall. The thermal-shock loading, coupled with the radiation-induced reduction in the material fracture toughness, introduces the possibility of propagation of preexistent flaws and what at one time were regarded as somewhat unique fracture-oriented conditions. Several postulated reactor accidents have been analyzed to discover flaw behavior trends; seven intermediate-scale thermal-shock experiments with steel cylinders have been conducted; and corresponding materials characterization studies have been performed. Flaw behavior trends and related fracture-mechanics data deduced from these studies are discussed

Using the Steel Vessel Material-Cost Index to Mitigate Shipbuilder Risk

National Research Council Canada - National Science Library

Keating, Edward G; Murphy, Robert; Schank, John F; Birkler, John

2008-01-01

This paper describes how the US Navy structures fixed-price and fixed-price, incentive-fee shipbuilding contracts and how labor- and material-cost indexes can mitigate shipbuilder risk in either type of contract...

Radiography for a Shock-accelerated Liquid Layer

International Nuclear Information System (INIS)

P. Meekunnasombat J.G. Oakley/inst M.H. Anderson R. Bonazza

2005-01-01

This program supported the experimental study of the interaction of planar shock waves with both solid structures (a single cylinder or a bank of cylinders) and single and multiple liquid layers. Objectives of the study included: characterization of the shock refraction patterns; measurements of the impulsive loading of the solid structures; observation of the response of the liquid layers to shock acceleration; assessment of the shock-mitigation effects of single and multiple liquid layers. The uploaded paper is intended as a final report for the entire funding period. The poster described in the paper won the Best Poster Award at the 25 International Symposium on Shock Waves

Towards a smoothed particle hydrodynamics algorithm for shocks through layered materials

NARCIS (Netherlands)

Zisis, I.A.; Linden, van der B.J.; Giannopapa, C.G.

2013-01-01

Hypervelocity impacts (HVIs) are collisions at velocities greater than the target object’s speed of sound. Such impacts produce pressure waves that generate sharp and sudden changes in the density of the materials. These are propagated as shock waves. Previous computational research has given

Stress wave propagation and mitigation in two polymeric foams

Science.gov (United States)

Pradel, Pierre; Malaise, Frederic; Cadilhon, Baptiste; Quessada, Jean-Hugues; de Resseguier, Thibaut; Delhomme, Catherine; Le Blanc, Gael

2017-06-01

Polymeric foams are widely used in industry for thermal insulation or shock mitigation. This paper investigates the ability of a syntactic epoxy foam and an expanded polyurethane foam to mitigate intense (several GPa) and short duration (<10-6 s) stress pulses. Plate impact and electron beam irradiation experiments have been conducted to study the dynamic mechanical responses of both foams. Interferometer Doppler Laser method is used to record the target rear surface velocity. A two-wave structure associated with the propagation of an elastic precursor followed by the compaction of the pores has been observed. The compaction stress level deduced from the velocity measurement is a good indicator of mitigation capability of the foams. Quasi-static tests and dynamic soft recovery experiments have also been performed to determine the compaction mechanisms. In the polyurethane foam, the pores are closed by elastic buckling of the matrix and damage of the structure. In the epoxy foam, the compaction is due to the crushing of glass microspheres. Two porous material models successfully represent the macroscopic response of these polymeric foams.

Numerical Study of Shock Wave Attenuation in Two-Dimensional Ducts Using Solid Obstacles: How to Utilize Shock Focusing Techniques to Attenuate Shock Waves

Directory of Open Access Journals (Sweden)

Qian Wan

2015-04-01

Full Text Available Research on shock wave mitigation in channels has been a topic of much attention in the shock wave community. One approach to attenuate an incident shock wave is to use obstacles of various geometries arranged in different patterns. This work is inspired by the study from Chaudhuri et al. (2013, in which cylinders, squares and triangles placed in staggered and non-staggered subsequent columns were used to attenuate a planar incident shock wave. Here, we present numerical simulations using a different obstacle pattern. Instead of using a matrix of obstacles, an arrangement of square or cylindrical obstacles placed along a logarithmic spiral curve is investigated, which is motivated by our previous work on shock focusing using logarithmic spirals. Results show that obstacles placed along a logarithmic spiral can delay both the transmitted and the reflected shock wave. For different incident shock Mach numbers, away from the logarithmic spiral design Mach number, this shape is effective to either delay the transmitted or the reflected shock wave. Results also confirm that the degree of attenuation depends on the obstacle shape, effective flow area and obstacle arrangement, much like other obstacle configurations.

Thermodynamic model of the compaction of powder materials by shock waves

NARCIS (Netherlands)

Dijken, Durandus; Hosson, J.Th.M. De

1994-01-01

For powder materials a model is proposed to predict the mean temperature behind the shock wave, the ratio between the increase of thermal energy and increase of total internal energy, as well as the mean final temperature after release of adiabatic pressure. Further, the change of pressure, specific

Material failure and inertial instabilities in a shocked imploded cylindrical aluminum sample

International Nuclear Information System (INIS)

Chandler, E.A.; Egan, P.; Stokes, J.

1998-01-01

The authors have used the LANL Pegasus Z-pinch facility to drive a thin cylindrically-convergent Al liner to ∼3 km/s to launch ∼30 GPa shocks in a 3-mm thick 10-mm-i.d. aluminum cylinder whose interior is filled with 1 atm Xe gas. The subsequent material motion of the metal and gas is diagnosed with both radial and axial flash x-rays and with optical framing cameras. Instabilities are seeded by implanting wires of assorted higher density metal parallel to the cylinder axis. The authors have done two shots, varying the target from Al 1100-O to Al 6061-T6 to explore the effect of changing material strength. The images show the spallation failure of the metal-gas interface on shock release and the effect of the seeded instabilities

Mechanical to electrical energy conversion by shock wave effect in a ferro-electric material

International Nuclear Information System (INIS)

David, Jean

1977-01-01

The shock wave propagation through a polarized ferroelectric ceramic changes or destroys remanent polarization and this way allows to get, in adequate electrical circuit, a volume energy of about 2 J/ cm 3 , during a time of the order of 0,4 μs; which corresponds to a peak - power of 5 MW/cm 3 . The present report has for objective to specify the optimum working conditions of this mechanical to electrical conversion from ceramic characteristics, load circuit connected to its electrodes and from the characteristics of the pressure wave which travels through the materials which constitute the converter. After a few lines about the ferroelectric materials and about the shock waves, the shock generator, the used setting and measures are described. A mathematical model which exhibits the transducer operation and a computation of the allowable electrical energy are given. For ending, the released electrical energies by industrial and laboratory ceramics are compared to the estimated computations and a thermodynamical balance is carried out. (author) [fr

Large-Scale Reactive Atomistic Simulation of Shock-induced Initiation Processes in Energetic Materials

Science.gov (United States)

Thompson, Aidan

2013-06-01

Initiation in energetic materials is fundamentally dependent on the interaction between a host of complex chemical and mechanical processes, occurring on scales ranging from intramolecular vibrations through molecular crystal plasticity up to hydrodynamic phenomena at the mesoscale. A variety of methods (e.g. quantum electronic structure methods (QM), non-reactive classical molecular dynamics (MD), mesoscopic continuum mechanics) exist to study processes occurring on each of these scales in isolation, but cannot describe how these processes interact with each other. In contrast, the ReaxFF reactive force field, implemented in the LAMMPS parallel MD code, allows us to routinely perform multimillion-atom reactive MD simulations of shock-induced initiation in a variety of energetic materials. This is done either by explicitly driving a shock-wave through the structure (NEMD) or by imposing thermodynamic constraints on the collective dynamics of the simulation cell e.g. using the Multiscale Shock Technique (MSST). These MD simulations allow us to directly observe how energy is transferred from the shockwave into other processes, including intramolecular vibrational modes, plastic deformation of the crystal, and hydrodynamic jetting at interfaces. These processes in turn cause thermal excitation of chemical bonds leading to initial chemical reactions, and ultimately to exothermic formation of product species. Results will be presented on the application of this approach to several important energetic materials, including pentaerythritol tetranitrate (PETN) and ammonium nitrate/fuel oil (ANFO). In both cases, we validate the ReaxFF parameterizations against QM and experimental data. For PETN, we observe initiation occurring via different chemical pathways, depending on the shock direction. For PETN containing spherical voids, we observe enhanced sensitivity due to jetting, void collapse, and hotspot formation, with sensitivity increasing with void size. For ANFO, we

Machine learning to analyze images of shocked materials for precise and accurate measurements

Energy Technology Data Exchange (ETDEWEB)

Dresselhaus-Cooper, Leora; Howard, Marylesa; Hock, Margaret C.; Meehan, B. T.; Ramos, Kyle J.; Bolme, Cindy A.; Sandberg, Richard L.; Nelson, Keith A.

2017-09-14

A supervised machine learning algorithm, called locally adaptive discriminant analysis (LADA), has been developed to locate boundaries between identifiable image features that have varying intensities. LADA is an adaptation of image segmentation, which includes techniques that find the positions of image features (classes) using statistical intensity distributions for each class in the image. In order to place a pixel in the proper class, LADA considers the intensity at that pixel and the distribution of intensities in local (nearby) pixels. This paper presents the use of LADA to provide, with statistical uncertainties, the positions and shapes of features within ultrafast images of shock waves. We demonstrate the ability to locate image features including crystals, density changes associated with shock waves, and material jetting caused by shock waves. This algorithm can analyze images that exhibit a wide range of physical phenomena because it does not rely on comparison to a model. LADA enables analysis of images from shock physics with statistical rigor independent of underlying models or simulations.

Classifying the mechanisms of electrochemical shock in ion-intercalation materials

OpenAIRE

Woodford, William; Carter, W. Craig; Chiang, Yet-Ming

2014-01-01

“Electrochemical shock” – the electrochemical cycling-induced fracture of materials – contributes to impedance growth and performance degradation in ion-intercalation batteries, such as lithium-ion. Using a combination of micromechanical models and acoustic emission experiments, the mechanisms of electrochemical shock are identified, classified, and modeled in targeted model systems with different composition and microstructure. A particular emphasis is placed on mechanical degradation occurr...

Insuring against Health Shocks: Health Insurance and Household Choices

OpenAIRE

Liu, Kai

2015-01-01

This paper provides empirical evidence on the role of public health insurance in mitigating adverse outcomes associated with health shocks. Exploiting the rollout of a universal health insurance program in rural China, I find that total household income and consumption are fully insured against health shocks even without access to health insurance. Household labor supply is an important insurance mechanism against health shocks. Access to health insurance helps households to maintain investme...

Flow control for oblique shock wave reflections

OpenAIRE

Giepman, R.H.M.

2016-01-01

Shock wave-boundary layer interactions are prevalent in many aerospace applications that involve transonic or supersonic flows. Such interactions may lead to boundary layer separation, flow unsteadiness and substantial losses in the total pressure. Flow control techniques can help to mitigate these adverse effects and stabilize the interaction. This thesis focuses on passive flow control techniques for oblique shock wave reflections on flat plates and presents experimental results for both la...

Gravitational shock waves and extreme magnetomaterial shock waves

International Nuclear Information System (INIS)

Lichnerowicz, Andre.

1975-01-01

Within an astrophysical context corresponding to high densities, a self-gravitating model is studied, which is the set of an extreme material medium of infinite conductivity and of a magnetic field. Corresponding shock waves generate necessarily, in general, gravitational shock waves [fr

Shock-Induced and Shock-Assisted Reaction Synthesis of Materials

National Research Council Canada - National Science Library

Thadhani, N. N

1997-01-01

The beneficial effects of shock-compression of powders and solid-state chemical reactions were utilized to synthesize Ti-Si and Ti-A1 intermetallics, Ti-B and Ti-C ceramics, and Ti-Si:Ti-A1 composites...

Material model validation for laser shock peening process simulation

International Nuclear Information System (INIS)

Amarchinta, H K; Grandhi, R V; Langer, K; Stargel, D S

2009-01-01

Advanced mechanical surface enhancement techniques have been used successfully to increase the fatigue life of metallic components. These techniques impart deep compressive residual stresses into the component to counter potentially damage-inducing tensile stresses generated under service loading. Laser shock peening (LSP) is an advanced mechanical surface enhancement technique used predominantly in the aircraft industry. To reduce costs and make the technique available on a large-scale basis for industrial applications, simulation of the LSP process is required. Accurate simulation of the LSP process is a challenging task, because the process has many parameters such as laser spot size, pressure profile and material model that must be precisely determined. This work focuses on investigating the appropriate material model that could be used in simulation and design. In the LSP process material is subjected to strain rates of 10 6  s −1 , which is very high compared with conventional strain rates. The importance of an accurate material model increases because the material behaves significantly different at such high strain rates. This work investigates the effect of multiple nonlinear material models for representing the elastic–plastic behavior of materials. Elastic perfectly plastic, Johnson–Cook and Zerilli–Armstrong models are used, and the performance of each model is compared with available experimental results

Gradually Increased Oxygen Administration Improved Oxygenation and Mitigated Oxidative Stress after Resuscitation from Severe Hemorrhagic Shock.

Science.gov (United States)

Luo, Xin; Yin, Yujing; You, Guoxing; Chen, Gan; Wang, Ying; Zhao, Jingxiang; Wang, Bo; Zhao, Lian; Zhou, Hong

2015-11-01

The optimal oxygen administration strategy during resuscitation from hemorrhagic shock (HS) is still controversial. Improving oxygenation and mitigating oxidative stress simultaneously seem to be contradictory goals. To maximize oxygen delivery while minimizing oxidative damage, the authors proposed the notion of gradually increased oxygen administration (GIOA), which entails making the arterial blood hypoxemic early in resuscitation and subsequently gradually increasing to hyperoxic, and compared its effects with normoxic resuscitation, hyperoxic resuscitation, and hypoxemic resuscitation in severe HS. Rats were subjected to HS, and on resuscitation, the rats were randomly assigned to four groups (n = 8): the normoxic, the hyperoxic, the hypoxemic, and the GIOA groups. Rats were observed for an additional 1 h. Hemodynamics, acid-base status, oxygenation, and oxidative injury were observed and evaluated. Central venous oxygen saturation promptly recovered only in the hyperoxic and the GIOA groups, and the liver tissue partial pressure of oxygen was highest in the GIOA group after resuscitation. Oxidative stress in GIOA group was significantly reduced compared with the hyperoxic group as indicated by the reduced malondialdehyde content, increased catalase activity, and the lower histologic injury scores in the liver. In addition, the tumor necrosis factor-α and interleukin-6 expressions in the liver were markedly decreased in the GIOA group than in the hyperoxic and normoxic groups as shown by the immunohistochemical staining. GIOA improved systemic/tissue oxygenation and mitigated oxidative stress simultaneously after resuscitation from severe HS. GIOA may be a promising strategy to improve resuscitation from HS and deserves further investigation.

Influence of edge conditions on material ejection from periodic grooves in laser shock-loaded tin

Energy Technology Data Exchange (ETDEWEB)

Rességuier, T. de; Roland, C. [Institut PPRIME, UPR 3346, CNRS, ENSMA, Université de Poitiers, 1 ave. Clément Ader, 86961 Futuroscope Cedex (France); Prudhomme, G.; Lescoute, E.; Mercier, P. [CEA, DAM, DIF, 91297 Arpajon (France); Loison, D. [Institut de Physique de Rennes, CNRS, Université de Rennes 1, 35042 Rennes (France)

2016-05-14

In a material subjected to high dynamic compression, the breakout of a shock wave at a rough free surface can lead to the ejection of high velocity debris. Anticipating the ballistic properties of such debris is a key safety issue in many applications involving shock loading, including pyrotechnics and inertial confinement fusion experiments. In this paper, we use laser driven shocks to investigate particle ejection from calibrated grooves of micrometric dimensions and approximately sinusoidal profile in tin samples, with various boundary conditions at the groove edges, including single groove and periodic patterns. Fast transverse shadowgraphy provides ejection velocities after shock breakout. They are found to depend not only on the groove depth and wavelength, as predicted theoretically and already observed in the past, but also, unexpectedly, on the edge conditions, with a jet tip velocity significantly lower in the case of a single groove than behind a periodic pattern.

Unusual behaviour of usual materials in shock waves

International Nuclear Information System (INIS)

Kanel, G I

2014-01-01

Exotic results of investigations of inelastic deformation and fracture under shock wave loading are presented and briefly discussed. Temperature effects on the flow stress at high strain rate may differ even in sign from those we observe at low and moderate strain rates. Investigations of the temperature-rate dependence of the yield stress at shock compression demonstrate intense multiplication of dislocations. At the highest strain rates, so-called ideal (ultimate) shear and tensile strength is reached in experiments with picosecond durations of shock loading. Although grain boundaries, in general, reduce resistance to fracture as compared to single crystals, the spall strength of ultra-fine-grained metals usually slightly exceeds that of coarse-grain samples. Failure wave phenomena have been observed in shock-compressed glasses.

Shock enhancement of cellular materials subjected to intensive pulse loading

Science.gov (United States)

Zhang, J.; Fan, J.; Wang, Z.; Zhao, L.; Li, Z.

2018-03-01

Cellular materials can dissipate a large amount of energy due to their considerable stress plateau, which contributes to their extensive applications in structural design for crashworthiness. However, in some experiments with specimens subjected to intense impact loads, transmitted stress enhancement has been observed, leading to severe damage to the objects protected. Transmitted stress through two-dimensional Voronoi cellular materials as a protective device is qualitatively studied in this paper. Dimensionless parameters of material properties and loading parameters are defined to give critical conditions for shock enhancement and clarify the correlation between the deformations and stress enhancement. The effect of relative density on this amplifying phenomenon is investigated as well. In addition, local strain fields are calculated by using the optimal local deformation gradient, which gives a clear presentation of deformations and possible local non-uniformity in the crushing process. This research provides valuable insight into the reliability of cellular materials as protective structures.

Insuring against health shocks: Health insurance and household choices.

Science.gov (United States)

Liu, Kai

2016-03-01

This paper provides empirical evidence on the role of public health insurance in mitigating adverse outcomes associated with health shocks. Exploiting the rollout of a universal health insurance program in rural China, I find that total household income and consumption are fully insured against health shocks even without access to health insurance. Household labor supply is an important insurance mechanism against health shocks. Access to health insurance helps households to maintain investment in children's human capital during negative health shocks, which suggests that one benefit of health insurance could arise from reducing the use of costly smoothing mechanisms. Copyright © 2016 Elsevier B.V. All rights reserved.

Shock resistance of composite material pipes

International Nuclear Information System (INIS)

Pays, M.F.

1995-01-01

Composite materials have found a wide range of applications for EDF nuclear plants. Applications include fire pipework, demineralized water, service water, and emergency-supplied service water piping. Some of those pipework is classified nuclear safety, their integrity (resistance to water aging and earthquakes or accidental excess pressure (water hammer)) must be safeguarded. As composite materials generally suffer damage for low energy impacts (under 10 J), the pipes planned for the Civaux power plant have been studied for their resistance to a low speed shock (0 to 50 m/s) and of a 0 to 110 J energy level. For three representative diameters (20, 150, 600 mm), the minimum impact energy that leads to a leak has been determined to be respectively 18, 20 and 48 J. Then the leak rate versus impact energy was plotted; until roughly 90 J, the leak rate remains stable at less than 25 cm 3 /h and raises to higher values (300 cm 3 /h) afterwards. The level of leakage in the range of impact energy tested always stays within the limits set by the Safety Authorities for metallic pipes. These results have been linked to destructive examinations, to clarify the damage mechanisms. Other tests are still ongoing to follow the evolution of the damage and of the leak rate while the pipe is maintained under service pressure during one year

Method of approximating the effects of blast mitigation materials on particulate-containing clouds formed by explosions

International Nuclear Information System (INIS)

Dyckes, G.W.

1983-09-01

A numerical model was developed for predicting the effect of blast mitigation materials on the rise and entrainment rate of explosively driven buoyant clouds containing radiotoxic particles. Model predictions for clouds from unmitigated explosions agree with published observations. More experimental data are needed to assess the validity of predictions for clouds from mitigated explosions

An investigation into the relationship between thermal shock resistance and ballistic performance of ceramic materials

Science.gov (United States)

Beaumont, Robert

Currently, there are no reliable methods for screening potential armour materials and hence full-scale ballistic trials are needed. These are both costly and time-consuming in terms of the actual test and also in the materials development that needs to take place to produce sufficient material to give a meaningful result. Whilst it will not be possible to dispense with ballistic trials before material deployment in armour applications, the ability to shorten the development cycle would be advantageous. The thermal shock performance of ceramic armour materials has been highlighted as potential marker for ballistic performance. Hence the purpose of this study was to investigate this further. A new thermal shock technique that reproduced features relevant to ballistic testing was sought. As it would be beneficial to have a simple test that did not use much material, a water-drop method was adopted. This was combined with a variety of characterisation techniques, administered pre- and post-shock. The methods included measurement of the amplitude of ultrasonic wave transmission through the sample alongside residual strength testing using a biaxial ball-on-ball configuration and reflected light and confocal microscopy. Once the protocols had been refined the testing regime was applied to a group of ceramic materials. The materials selected were from two broad groups: alumina and carbide materials. Carbide ceramics show superior performance to alumina ceramics in ballistic applications so it was essential that any screening test would be easily able to differentiate the two groups. Within the alumina family, two commercially available materials, AD995 and Sintox FA, were selected. These were tested alongside three developmental silicon carbide-boron carbide composites, which had identical chemical compositions but different microstructures and thus presented more of a challenge in terms of differentiation. The results from the various tests were used to make predictions

The Shock and Vibration Bulletin. Part 4. Dynamic Properties of Materials, Applications of Materials, Shock and Blast, Fragments

Science.gov (United States)

1980-09-01

individual m.crophone readings using the following standard formula: SPI- AVE " ,0 LOG ( S lOSPM/lo/n) i*I ’ where: SPLAVE " Sound pressure...Godes- berg 1975 |4| NEIER-DemBERG. K.-E.i ’Reference Pa- rameters for Shock Inputs and Shock Tolerance Limits. ACARO Conference Proceedings No...occurrence In the Polsson counting process, equals v.{t), the av - erage barrier crossing rate of the response ran- dom process for a barrier with

Flow control for oblique shock wave reflections

NARCIS (Netherlands)

Giepman, R.H.M.

2016-01-01

Shock wave-boundary layer interactions are prevalent in many aerospace applications that involve transonic or supersonic flows. Such interactions may lead to boundary layer separation, flow unsteadiness and substantial losses in the total pressure. Flow control techniques can help to mitigate these

Development of in situ time-resolved Raman spectroscopy facility for dynamic shock loading in materials

Science.gov (United States)

Chaurasia, S.; Rastogi, V.; Rao, U.; Sijoy, C. D.; Mishra, V.; Deo, M. N.

2017-11-01

The transient state of excitation and relaxation processes in materials under shock compression can be investigated by coupling the laser driven shock facility with Raman spectroscopy. For this purpose, a time resolved Raman spectroscopy setup has been developed to monitor the physical and the chemical changes such as phase transitions, chemical reactions, molecular kinetics etc., under shock compression with nanosecond time resolution. This system consist of mainly three parts, a 2 J/8 ns Nd:YAG laser system used for generation of pump and probe beams, a Raman spectrometer with temporal and spectral resolution of 1.2 ns and 3 cm-1 respectively and a target holder in confinement geometry assembly. Detailed simulation for the optimization of confinement geometry targets is performed. Time resolved measurement of polytetrafluoroethylene (PTFE) targets at focused laser intensity of 2.2 GW/cm2 has been done. The corresponding pressure in the Aluminum and PTFE are 3.6 and 1.7 GPa respectively. At 1.7 GPa in PTFE, a red shift of 5 cm-1 is observed for the CF2 twisting mode (291 cm-1). Shock velocity in PTFE is calculated by measuring rate of change of ratios of the intensity of Raman lines scattered from shocked volume to total volume of sample in the laser focal spot along the laser axis. The calculated shock velocity in PTFE is found to be 1.64 ± 0.16 km/s at shock pressure of 1.7 GPa, for present experimental conditions.

Nonzero-Sum Relationships in Mitigating Urban Carbon Emissions: A Dynamic Network Simulation.

Science.gov (United States)

Chen, Shaoqing; Chen, Bin; Su, Meirong

2015-10-06

The "stove-pipe" way of thinking has been mostly used in mitigating carbon emissions and managing socioeconomics because of its convenience of implementation. However, systems-oriented approaches become imperative in pursuit of an efficient regulation of carbon emissions from systems as complicated as urban systems. The aim of this paper is to establish a dynamic network approach that is capable of assessing the effectiveness of carbon emissions mitigation in a more holistic way. A carbon metabolic network is constructed by modeling the carbon flows between economic sectors and environment. With the network shocked by interventions to the sectoral carbon flows, indirect emissions from the city are accounted for under certain carbon mitigation strategies. The nonzero-sum relationships between sectors and environmental components are identified based on utility analysis, which synthesize the nature of direct and indirect network interactions. The results of the case study of Beijing suggest that the stove-pipe mitigation strategies targeted the economic sectors might be not as efficient as they were expected. A direct cutting in material or energy import to the sectors may result in a rebound in indirect emissions and thus fails to achieve the carbon mitigation goal of the city as a whole. A promising way of foreseeing the dynamic mechanism of emissions is to analyze the nonzero-sum relationships between important urban components. Thinking cities as systems of interactions, the network approach is potentially a strong tool for appraising and filtering mitigation strategies of carbon emissions.

Thermal shock investigation of silicon nitride

International Nuclear Information System (INIS)

Ziegler, G.; Leucht, R.

1977-01-01

In this work, the thermal shock properties of commercial reaction-bonded Si 3 N 4 quality material (RBSN), of commercial hot-pressed Si 3 N 4 (HPSN) and of different laboratory grades of hot-pressed Si 3 N 4 were examined. The thermal shock properties of RBSN quality material differ according to the structure considerably: The critical temperature difference for sample crossections of 5 x 5 or 6 x 6 mm after quenching in oil lies between 730 0 C and over 1400 0 C. The best thermal shock properties are shown by high density RBSN quality material having very fine pores and high initial strength. The results indicate that for RBSN large pores and density inhomogenities are responsible for bad thermal shock properties. Resistance to fast temperature change is higher for hot-pressed Si 3 N 4 than for RBSN quality material. In HPSN, the thermal shock results show dependence on structure. High MgO content and the associated coarse rod-shaped configuration of the β phase and structural inhomogenities affect the thermal shock properties in an adverse way. (orig.) [de

Relationship of material properties to seismic coupling. Part I. Shock wave studies of rock and rock-like materials

International Nuclear Information System (INIS)

Larson, D.B.; Rodean, H.C.

1975-01-01

Our research seeks an understanding of the relationship of material properties to explosive-energy coupling in various earth media by integrating experimental observations with computer calculational models to obtain a predictive capability. The procedure chosen consists of: first, selecting materials exhibiting interesting values of the properties that are believed to control coupling; second, experimentally determining material behavior under various types of loading and unloading; third, development of constitutive relationships; fourth, adapting these constitutive relationships to computer calculational models; and fifth, verifying the calculational models through comparison with small-scale and field high-strain-rate experiments. The object of this report is to present the shock-wave data and to make a preliminary evaluation of the results in terms of material properties, coupling, and their interactions. (U.S.)

Shock formation of HCO+

International Nuclear Information System (INIS)

Elitzur, M.

1983-01-01

It is shown that shocks propagating in dense molecular regions will lead to a decrease in HCO + relative abundance, in agreement with previous results by Iglesias and Silk. The shock enhancement of HCO + detected in the supernova remnant IC 443 by Dickenson et al. is due to enhanced ionization in the shocked material. This is the result of the material penetrating the remnant cavity where it becomes exposed to the trapped cosmic rays. A similar enhancement appears to have been detected by Wootten in W28 and is explained by the same model

Developing high-risk scenarios and countermeasure ideas for mitigation of hazardous materials incidents

International Nuclear Information System (INIS)

Russell, E.R. Sr.

1991-01-01

Kansas State University (KSU) conducted a comprehensive study of the development of a set of prioritized, extreme-risk scenarios, the development of a set of feasible, practical and implementable protective systems, and a report to summarize guidelines on the use of these protective systems to mitigate potential, extreme-risk situations that could occur during the transport of hazardous materials (Hazmat) on our highway system. This paper covers the methodology used to compete the first tow objectives with use of a state's panel. The research study was limited to materials (such as LNG, propane, gasoline, etc.) spilled within the highway system. It focused on potential risks which would result in severe, long-term, permanent, irreparable or catastrophic consequences, and existing technology and state-of-the-art knowledge for development of protective systems to mitigate these consequences. The protective systems within the scope of this study were systems constructed or physically incorporated into the highway system or modifications thereto

Low carbon content and carbon-free refractory materials with high thermal shock resistance; Thermoschockbestaendige feuerfeste Erzeugnisse mit geringerem Kohlenstoffgehalt bzw. kohlenstofffreie Erzeugnisse

Energy Technology Data Exchange (ETDEWEB)

Brachhold, Nora; Aneziris, C.G.; Stein, Volker; Roungos, Vasileios; Moritz, Kirsten [TU Bergakademie Freiberg (TUBAF) (DE). Inst. fuer Keramik, Glas- und Baustofftechnik (IKGB)

2012-07-01

Carbon bonded refractories are essential for steelmaking due to their excellent thermal shock resistance. The research on carbon reduced and carbon-free materials is necessary to manufacture high quality stainless steels tending carbon pick-up in contact to conventional refractory materials. Further advantages are reduced emissions of CO{sub 2} and energy saving potentials due to better heat insulation properties. The challenge is to develop alternative materials with lower carbon contents but with the necessary thermal shock resistance. The Priority Programme 1418 funded by the German Research Foundation (DFG) concentrates on this problem. In this article two materials are presented. First, the carbon content could be reduced by nanoscaled additives resulting in better bonding between matrix and oxidic components. Second, an AL{sub 2}O{sub 3}-rich carbon-free material is presented showing a very good thermal shock resistance due to its designed microstructure. Finally, a steel casting simulator is introduced to test the new materials under nearly real conditions. (orig.)

Attenuation of stress waves in single and multi-layered structures. [mitigation of elastic and plastic stress waves during spacecraft landing

Science.gov (United States)

Yang, J. C. S.; Tsui, C. Y.

1972-01-01

Analytical and experimental studies were made of the attenuation of the stress waves during passage through single and multilayer structures. The investigation included studies on elastic and plastic stress wave propagation in the composites and those on shock mitigating material characteristics such as dynamic stress-strain relations and energy absorbing properties. The results of the studies are applied to methods for reducing the stresses imposed on a spacecraft during planetary or ocean landings.

Shocked materials at the intersection of experiment and simulation

Energy Technology Data Exchange (ETDEWEB)

Lorenzana, H. E.; Belak, J. F.; Bradley, K. S.; Bringa, E. M.; Budil, K. S.; Cazamias, J. U.; El-Dasher, B.; Hawreliak, J. A.; Hessler, J.; Kadau, K.; Kalantar, D. H.; McNaney, J. M.; Milathianaki, D.; Rosolankova, K.; Swift, D. C.; Taravillo, M.; Van Buuren, T. W.; Wark, J. S.; de la Rubia, T. Diaz

2008-04-01

Understanding the dynamic lattice response of solids under the extreme conditions of pressure, temperature and strain rate is a scientific quest that spans nearly a century. Critical to developing this understanding is the ability to probe and model the spatial and temporal evolution of the material microstructure and properties at the scale of the relevant physical phenomena-nanometers to micrometers and picoseconds to nanoseconds. While experimental investigations over this range of spatial and temporal scales were unimaginable just a decade ago, new technologies and facilities currently under development and on the horizon have brought these goals within reach for the first time. The equivalent advancements in simulation capabilities now mean that we can conduct simulations and experiments at overlapping temporal and spatial scales. In this article, we describe some of our studies which exploit existing and new generation ultrabright, ultrafast x-ray sources and large scale molecular dynamics simulations to investigate the real-time physical phenomena that control the dynamic response of shocked materials.

Shocked materials at the intersection of experiment and simulation

Energy Technology Data Exchange (ETDEWEB)

Kadau, Kai [Los Alamos National Laboratory

2008-01-01

Understanding the dynamic lattice response of solids under the extreme conditions of pressure, temperature and strain rate is a scientific quest that spans nearly a century. Critical to developing this understanding is the ability to probe and model the spatial and temporal evolution of the material microstructure and properties at the scale of the relevant physical phenomena -- nanometers to micrometers and picoseconds to nanoseconds. While experimental investigations over this range of spatial and temporal scales were unimaginable just a decade ago, new technologies and facilities currently under development and on the horizon have brought these goals within reach for the first time. The equivalent advancements in simulation capabilities now mean that we can conduct simulations and experiments at overlapping temporal and spatial scales. In this article, we describe some of our studies which exploit existing and new generation ultrabright, ultrafast x-ray sources and large scale molecular dynamics simulations to investigate the real-time physical phenomena that control the dynamic response of shocked materials.

Experimental analysis of shock wave effects in copper

International Nuclear Information System (INIS)

Llorca, Fabrice; Buy, Francois; Farre, Jose

2002-01-01

This paper proposes the analysis of shock wave effects for a high purity copper. The method developed is based on the analysis of the mechanical behavior of as received and shocked materials. Shock effect is generated through plates impact tests performed in the range 9 GPa to 12 GPa on a single stage light gas gun. Therefore, as-received and impacted materials are characterized on quasi static and Split Hopkinson apparatus. The difference between measured stresses between as received and shocked materials allows to understand shock effects in the low pressure range of study. A specific modeling approach is engaged in order to give indications about the evolution of the microstructure of the materials

Laser shocks: A tool for experimental simulation of damage into materials

Energy Technology Data Exchange (ETDEWEB)

Boustie, M.; Cuq Lelandais, J. P.; Berthe, L.; Ecault, R. [Institut PPRIME, Departement Physique et Mecanique des Materiaux, CNRS-ENSMA-Universite de Poitiers, 1 av Clement Ader, 86961 FUTUROSCOPE Cedex (France); CEA-DAM Valduc, 21120 Is-sur-Tille (France); Laboratoire Procedes et Ingenierie en Mecanique et Materiaux (CNRS), Arts et Metiers ParisTech, 151 bd de l' Hopital, 75013 PARIS (France); Institut PPRIME, Departement Physique et Mecanique des Materiaux, CNRS-ENSMA-Universite de Poitiers, 1 av Clement Ader, 86961 FUTUROSCOPE Cedex (France)

2012-07-30

High power laser irradiation of solids results in a strong shock wave propagation, driving very high amplitude pressure loadings with very short durations. These particular characteristics offer the possibility to study the behaviour of matter under extreme dynamic conditions in continuity with what is possible with the conventional generators of shock (launchers of projectiles, explosives). An advantage of laser shocks is a possible recovery of the shocked samples presenting the metallurgical effects of the shock in most cases. We introduce the principle of the laser shock generation, the characterization of these shocks, the principal mechanisms and effects associated with their propagation in the solids. We show how laser shocks can be a laboratory tool for simulating shock effects at ultra high strain rate, providing a high in information experimental layout for validation of damage modelling on an extended strain rate range compared to conventional shock generators. New data have been obtained with ultra short femtosecond range irradiation. Experimental data gathered through post mortem observation, time resolved velocity measurement are shown along with numerical associated simulations, showing the possibility to predict the damage behaviour of metallic targets under extreme strain rate up to 10{sup 8} s{sup -1}.

Observation of the shock wave propagation induced by a high-power laser irradiation into an epoxy material

International Nuclear Information System (INIS)

Ecault, Romain; Boustie, Michel; Touchard, Fabienne; Berthe, Laurent; Lescoute, Emilien; Sollier, Arnaud; Mercier, Patrick; Benier, Jacky

2013-01-01

The propagation of laser-induced shock waves in a transparent epoxy sample is investigated by optical shadowgraphy. The shock waves are generated by a focused laser (3 ns pulse duration—1.2 to 3.4 TW cm −2 ) producing pressure from 44 to 98.9 GPa. It is observed that the shock wave and the release wave created by the shock reverberation at the rear face are both followed by a dark zone in the pictures. This corresponds to the creation of a tensile zone resulting from the crossing on the loading axis of the release waves coming from the edge of the impact area (2D effects). After the laser shock experiment, the residual stresses in the targets are identified and quantified through a photoelasticimetry analysis of the recovered samples. This work results in a new set of original data which can be directly used to validate numerical models implemented to reproduce the behaviour of epoxy under extreme strain rate loading. The residual stresses observed prove that the high-pressure shocks can modify the pure epoxy properties, which could have an influence on the use made of these materials. (paper)

Numerical studies of cavitation erosion on an elastic-plastic material caused by shock-induced bubble collapse

Science.gov (United States)

Turangan, C. K.; Ball, G. J.; Jamaluddin, A. R.; Leighton, T. G.

2017-09-01

We present a study of shock-induced collapse of single bubbles near/attached to an elastic-plastic solid using the free-Lagrange method, which forms the latest part of our shock-induced collapse studies. We simulated the collapse of 40 μm radius single bubbles near/attached to rigid and aluminium walls by a 60 MPa lithotripter shock for various scenarios based on bubble-wall separations, and the collapse of a 255 μm radius bubble attached to aluminium foil with a 65 MPa lithotripter shock. The coupling of the multi-phases, compressibility, axisymmetric geometry and elastic-plastic material model within a single solver has enabled us to examine the impingement of high-speed liquid jets from the shock-induced collapsing bubbles, which imposes an extreme compression in the aluminium that leads to pitting and plastic deformation. For certain scenarios, instead of the high-speed jet, a radially inwards flow along the aluminium surface contracts the bubble to produce a `mushroom shape'. This work provides methods for quantifying which parameters (e.g. bubble sizes and separations from the solid) might promote or inhibit erosion on solid surfaces.

Fundamental structure of steady plastic shock waves in metals

Science.gov (United States)

Molinari, A.; Ravichandran, G.

2004-02-01

The propagation of steady plane shock waves in metallic materials is considered. Following the constitutive framework adopted by R. J. Clifton [Shock Waves and the Mechanical Properties of Solids, edited by J. J. Burke and V. Weiss (Syracuse University Press, Syracuse, N.Y., 1971), p. 73] for analyzing elastic-plastic transient waves, an analytical solution of the steady state propagation of plastic shocks is proposed. The problem is formulated in a Lagrangian setting appropriate for large deformations. The material response is characterized by a quasistatic tensile (compression) test (providing the isothermal strain hardening law). In addition the elastic response is determined up to second order elastic constants by ultrasonic measurements. Based on this simple information, it is shown that the shock kinetics can be quite well described for moderate shocks in aluminum with stress amplitude up to 10 GPa. Under the later assumption, the elastic response is assumed to be isentropic, and thermomechanical coupling is neglected. The model material considered here is aluminum, but the analysis is general and can be applied to any viscoplastic material subjected to moderate amplitude shocks. Comparisons with experimental data are made for the shock velocity, the particle velocity and the shock structure. The shock structure is obtained by quadrature of a first order differential equation, which provides analytical results under certain simplifying assumptions. The effects of material parameters and loading conditions on the shock kinetics and shock structure are discussed. The shock width is characterized by assuming an overstress formulation for the viscoplastic response. The effects on the shock structure of strain rate sensitivity are analyzed and the rationale for the J. W. Swegle and D. E. Grady [J. Appl. Phys. 58, 692 (1985)] universal scaling law for homogeneous materials is explored. Finally, the ability to deduce information on the viscoplastic response of

Fundamental structure of steady plastic shock waves in metals

International Nuclear Information System (INIS)

Molinari, A.; Ravichandran, G.

2004-01-01

The propagation of steady plane shock waves in metallic materials is considered. Following the constitutive framework adopted by R. J. Clifton [Shock Waves and the Mechanical Properties of Solids, edited by J. J. Burke and V. Weiss (Syracuse University Press, Syracuse, N.Y., 1971), p. 73] for analyzing elastic-plastic transient waves, an analytical solution of the steady state propagation of plastic shocks is proposed. The problem is formulated in a Lagrangian setting appropriate for large deformations. The material response is characterized by a quasistatic tensile (compression) test (providing the isothermal strain hardening law). In addition the elastic response is determined up to second order elastic constants by ultrasonic measurements. Based on this simple information, it is shown that the shock kinetics can be quite well described for moderate shocks in aluminum with stress amplitude up to 10 GPa. Under the later assumption, the elastic response is assumed to be isentropic, and thermomechanical coupling is neglected. The model material considered here is aluminum, but the analysis is general and can be applied to any viscoplastic material subjected to moderate amplitude shocks. Comparisons with experimental data are made for the shock velocity, the particle velocity and the shock structure. The shock structure is obtained by quadrature of a first order differential equation, which provides analytical results under certain simplifying assumptions. The effects of material parameters and loading conditions on the shock kinetics and shock structure are discussed. The shock width is characterized by assuming an overstress formulation for the viscoplastic response. The effects on the shock structure of strain rate sensitivity are analyzed and the rationale for the J. W. Swegle and D. E. Grady [J. Appl. Phys. 58, 692 (1985)] universal scaling law for homogeneous materials is explored. Finally, the ability to deduce information on the viscoplastic response of

Modelling of thermal shock experiments of carbon based materials in JUDITH

Science.gov (United States)

Ogorodnikova, O. V.; Pestchanyi, S.; Koza, Y.; Linke, J.

2005-03-01

The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments.

Modelling of thermal shock experiments of carbon based materials in JUDITH

International Nuclear Information System (INIS)

Ogorodnikova, O.V.; Pestchanyi, S.; Koza, Y.; Linke, J.

2005-01-01

The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments

Modelling of thermal shock experiments of carbon based materials in JUDITH

Energy Technology Data Exchange (ETDEWEB)

Ogorodnikova, O.V. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany)]. E-mail: o.ogorodnikova@fz-juelich.de; Pestchanyi, S. [Forschungszentrum Karlsruhe, EURATOM-Associaton, IHM, 76021 Karlsruhe (Germany); Koza, Y. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany); Linke, J. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany)

2005-03-01

The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments.

Surface instabilities in shock loaded granular media

Science.gov (United States)

Kandan, K.; Khaderi, S. N.; Wadley, H. N. G.; Deshpande, V. S.

2017-12-01

The initiation and growth of instabilities in granular materials loaded by air shock waves are investigated via shock-tube experiments and numerical calculations. Three types of granular media, dry sand, water-saturated sand and a granular solid comprising PTFE spheres were experimentally investigated by air shock loading slugs of these materials in a transparent shock tube. Under all shock pressures considered here, the free-standing dry sand slugs remained stable while the shock loaded surface of the water-saturated sand slug became unstable resulting in mixing of the shocked air and the granular material. By contrast, the PTFE slugs were stable at low pressures but displayed instabilities similar to the water-saturated sand slugs at higher shock pressures. The distal surfaces of the slugs remained stable under all conditions considered here. Eulerian fluid/solid interaction calculations, with the granular material modelled as a Drucker-Prager solid, reproduced the onset of the instabilities as seen in the experiments to a high level of accuracy. These calculations showed that the shock pressures to initiate instabilities increased with increasing material friction and decreasing yield strain. Moreover, the high Atwood number for this problem implied that fluid/solid interaction effects were small, and the initiation of the instability is adequately captured by directly applying a pressure on the slug surface. Lagrangian calculations with the directly applied pressures demonstrated that the instability was caused by spatial pressure gradients created by initial surface perturbations. Surface instabilities are also shown to exist in shock loaded rear-supported granular slugs: these experiments and calculations are used to infer the velocity that free-standing slugs need to acquire to initiate instabilities on their front surfaces. The results presented here, while in an idealised one-dimensional setting, provide physical understanding of the conditions required to

Numerical results from a study of LiH: the proposed standard material for the high pressure shock experiment

International Nuclear Information System (INIS)

Rogers, F.J.

1975-01-01

It is proposed to send a high pressure shock wave through a layer of LiH and then into a sample of high Z-material, resulting in a reflected shock wave back into the LiH. If the Hugoniot and some reflected Hugoniots for LiH are known the EOS of the sample can be obtained from the ''impedance matching method.'' The theory and its range of validity are described

Melting under shock compression

International Nuclear Information System (INIS)

Bennett, B.I.

1980-10-01

A simple model, using experimentally measured shock and particle velocities, is applied to the Lindemann melting formula to predict the density, temperature, and pressure at which a material will melt when shocked from room temperature and zero pressure initial conditions

Shock Response of Boron Carbide

National Research Council Canada - National Science Library

Dandekar, D. P. (Dattatraya Purushottam)

2001-01-01

.... The present work was undertaken to determine tensile/spall strength of boron carbide under plane shock wave loading and to analyze all available shock compression data on boron carbide materials...

Dynamic analysis to establish normal shock and vibration of radioactive material shipping packages

International Nuclear Information System (INIS)

Fields, S.R.

1980-01-01

A computer model, CARDS (Cask-Railcar Dynamic Simulator) was developed to provide input data for a broad range of radioactive material package-tiedown structural assessments. CARDS simulates the dynamic behavior of shipping packages and their transporters during normal transport conditions. The model will be used to identify parameters which significantly affect the normal shock and vibration environments which, in turn, provide the basis for determining the forces transmitted to the packages

Shock absorber

International Nuclear Information System (INIS)

Housman, J.J.

1978-01-01

A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

Laser Shock Processing of Metallic Materials: Coupling of Laser-Plasma Interaction and Material Behaviour Models for the Assessment of Key Process Issues

International Nuclear Information System (INIS)

Ocana, J. L.; Morales, M.; Molpeceres, C.; Porro, J. A.

2010-01-01

Profiting by the increasing availability of laser sources delivering intensities above 109 W/cm 2 with pulse energies in the range of several Joules and pulse widths in the range of nanoseconds, laser shock processing (LSP) is consolidating as an effective technology for the improvement of surface mechanical and corrosion resistance properties of metals. The main advantage of the laser shock processing technique consists on its capability of inducing a relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly, the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Although significant work from the experimental side has been contributed to explore the optimum conditions of application of the treatments and to assess their ultimate capability to provide enhanced mechanical behaviour to work-pieces of typical materials, only limited attempts have been developed in the way of full comprehension and predictive assessment of the characteristic physical processes and material transformations with a specific consideration of real material properties. In the present paper, a review on the physical issues dominating the development of LSP processes from a high intensity laser-matter interaction point of view is presented along with the theoretical and computational methods developed by the authors for their predictive assessment and practical results at laboratory scale on the application of the technique to different materials.

Analysis and Mitigation of Mechanical Shock Effects on High Speed Planing Boats

National Research Council Canada - National Science Library

Keams, Sean

2001-01-01

.... Operation of these boats, particularly in rough seas, exposes the occupants to severe mechanical shock exposure that has been linked to significant increase in the rates of acute and chronic injury...

Mitigating Voltage Decay of Li-Rich Cathode Material via Increasing Ni Content for Lithium-Ion Batteries.

Science.gov (United States)

Shi, Ji-Lei; Zhang, Jie-Nan; He, Min; Zhang, Xu-Dong; Yin, Ya-Xia; Li, Hong; Guo, Yu-Guo; Gu, Lin; Wan, Li-Jun

2016-08-10

Li-rich layered materials have been considered as the most promising cathode materials for future high-energy-density lithium-ion batteries. However, they suffer from severe voltage decay upon cycling, which hinders their further commercialization. Here, we report a Li-rich layered material 0.5Li2MnO3·0.5LiNi0.8Co0.1Mn0.1O2 with high nickel content, which exhibits much slower voltage decay during long-term cycling compared to conventional Li-rich materials. The voltage decay after 200 cycles is 201 mV. Combining in situ X-ray diffraction (XRD), ex situ XRD, ex situ X-ray photoelectron spectroscopy, and scanning transmission electron microscopy, we demonstrate that nickel ions act as stabilizing ions to inhibit the Jahn-Teller effect of active Mn(3+) ions, improving d-p hybridization and supporting the layered structure as a pillar. In addition, nickel ions can migrate between the transition-metal layer and the interlayer, thus avoiding the formation of spinel-like structures and consequently mitigating the voltage decay. Our results provide a simple and effective avenue for developing Li-rich layered materials with mitigated voltage decay and a long lifespan, thereby promoting their further application in lithium-ion batteries with high energy density.

Young’s modulus evaluation and thermal shock behavior of a porous SiC/cordierite composite material

Directory of Open Access Journals (Sweden)

Pošarac-Marković M.

2015-01-01

Full Text Available Porous SiC/Cordierite Composite Material with graphite content (10% was synthesized. Evaluation of Young modulus of elasticity and thermal shock behavior of these samples was presented. Thermal shock behavior was monitored using water quench test, and non destructive methods such are UPVT and image analysis were also used for accompaniment the level of destruction of the samples during water quench test. Based on the level of destruction graphical modeling of critical number of cycles was given. This approach was implemented on discussion of the influence of the graphite content on thermal stability behavior of the samples. [Projekat Ministarstva nauke Republike Srbije, br. III 45012

Spherical strong-shock generation for shock-ignition inertial fusion

Energy Technology Data Exchange (ETDEWEB)

Theobald, W.; Seka, W.; Lafon, M.; Anderson, K. S.; Hohenberger, M.; Marshall, F. J.; Michel, D. T.; Solodov, A. A.; Stoeckl, C.; Edgell, D. H.; Yaakobi, B.; Shvydky, A. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Nora, R.; Betti, R. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Department of Mechanical Engineering and Department of Physics, University of Rochester, Rochester, New York 14623 (United States); Casner, A.; Reverdin, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Ribeyre, X.; Vallet, A. [Université de Bordeaux-CNRS-CEA, CELIA (Centre Lasers Intenses et Applications) UMR 5107 F-33400 Talence (France); Peebles, J.; Beg, F. N. [University of California, San Diego, La Jolla, California 92093 (United States); and others

2015-05-15

Recent experiments on the Laboratory for Laser Energetics' OMEGA laser have been carried out to produce strong shocks in solid spherical targets with direct laser illumination. The shocks are launched at pressures of several hundred Mbars and reach Gbar upon convergence. The results are relevant to the validation of the shock-ignition scheme and to the development of an OMEGA experimental platform to study material properties at Gbar pressures. The experiments investigate the strength of the ablation pressure and the hot-electron production at incident laser intensities of ∼2 to 6 × 10{sup 15 }W/cm{sup 2} and demonstrate ablation pressures exceeding 300 Mbar, which is crucial to developing a shock-ignition target design for the National Ignition Facility. The timing of the x-ray flash from shock convergence in the center of the solid plastic target is used to infer the ablation and shock pressures. Laser–plasma instabilities produce hot-electrons with a moderate temperature (<100 keV). The instantaneous conversion efficiencies of laser power into hot-electron power reached up to ∼15% in the intensity spike. The large amount of hot electrons is correlated with an earlier x-ray flash and a strong increase in its magnitude. This suggests that hot electrons contribute to the augmentation of the shock strength.

Thermal shock considerations for the TFCX limiter and first wall

International Nuclear Information System (INIS)

Haines, J.R.; Fuller, G.M.

1983-01-01

Resistance to thermal shock fracture of limiter and first wall surface material candidates during plasma disruption heating conditions is evaluated. A simple, figure-of-merit type thermal shock parameter which provides a mechanism to rank material candidates is derived. Combining this figure-of-merit parameter with the parameters defining specific heating conditions yields a non-dimensional thermal shock parameter. For values of this parameter below a critical value, a given material is expected to undergo thermal shock damage. Prediction of thermal shock damage with this parameter is shown to exhibit good agreement with test data. Applying this critical parameter value approach, all materials examined in this study are expected to experience thermal shock damage for nominal TFCX plasma disruption conditions. Since the extent of this damage is not clear, tests which explore the range of expected conditions for TFCX are recommended

Molecular dynamics simulation of laser shock phenomena

Energy Technology Data Exchange (ETDEWEB)

Fukumoto, Ichirou [Japan Atomic Energy Research Inst., Kansai Research Establishment, Advanced Photon Research Center, Neyagawa, Osaka (Japan).

2001-10-01

Recently, ultrashort-pulse lasers with high peak power have been developed, and their application to materials processing is expected as a tool of precision microfabrication. When a high power laser irradiates, a shock wave propagates into the material and dislocations are generated. In this paper, laser shock phenomena of the metal were analyzed using the modified molecular dynamics method, which has been developed by Ohmura and Fukumoto. The main results obtained are summarized as follows: (1) The shock wave induced by the Gaussian beam irradiation propagates radially from the surface to the interior. (2) A lot of dislocations are generated at the solid-liquid interface by the propagation of a shock wave. (3) Some dislocations are moved instantaneously with the velocity of the longitudinal wave when the shock wave passes, and their velocity is not larger than the transverse velocity after the shock wave has passed. (author)

Thermal shock tests to qualify different tungsten grades as plasma facing material

Science.gov (United States)

Wirtz, M.; Linke, J.; Loewenhoff, Th; Pintsuk, G.; Uytdenhouwen, I.

2016-02-01

The electron beam device JUDITH 1 was used to establish a testing procedure for the qualification of tungsten as plasma facing material. Absorbed power densities of 0.19 and 0.38 GW m-2 for an edge localized mode-like pulse duration of 1 ms were chosen. Furthermore, base temperatures of room temperature, 400 °C and 1000 °C allow investigating the thermal shock performance in the brittle, ductile and high temperature regime. Finally, applying 100 pulses under all mentioned conditions helps qualifying the general damage behaviour while with 1000 pulses for the higher power density the influence of thermal fatigue is addressed. The investigated reference material is a tungsten product produced according to the ITER material specifications. The obtained results provide a general overview of the damage behaviour with quantified damage characteristics and thresholds. In particular, it is shown that the damage strongly depends on the microstructure and related thermo-mechanical properties.

Shock compression of simulated adobe

Science.gov (United States)

Braithwaite, C. H.; Church, P. D.; Gould, P. J.; Stewart, B.; Jardine, A. P.

2017-01-01

A series of plate impact experiments were conducted to investigate the shock response of a simulant for adobe, a traditional form of building material widely used around the world. Air dried bricks were sourced from the London brick company, dry machined and impacted at a range of velocities in a single stage gas gun. The shock Hugoniot was determined (Us =2.26up+0.37) as well as release information. The material was found to behave in a manner which was similar to that of loose sand and considerably less stiff than a weak porous sandstone. The effect of any cementing of the grains was examined by shocking powdered samples contained within a cell arrangement.

Shock and rarefaction waves in a hyperbolic model of incompressible materials

Directory of Open Access Journals (Sweden)

Tommaso Ruggeri

2013-01-01

Full Text Available The aim of the present paper is to investigate shock and rarefaction waves in a hyperbolic model of incompressible materials. To this aim, we use the so-called extended quasi-thermal-incompressible (EQTI model, recently proposed by Gouin & Ruggeri (H. Gouin, T. Ruggeri, Internat. J. Non-Linear Mech. 47 688–693 (2012. In particular, we use as constitutive equation a variant of the well-known Bousinnesq approximation in which the specific volume depends not only on the temperature but also on the pressure. The limit case of ideal incompressibility, namely when the thermal expansion coefficient and the compressibility factor vanish, is also considered.

Two-material optimization of plate armour for blast mitigation using hybrid cellular automata

Science.gov (United States)

Goetz, J.; Tan, H.; Renaud, J.; Tovar, A.

2012-08-01

With the increased use of improvised explosive devices in regions at war, the threat to military and civilian life has risen. Cabin penetration and gross acceleration are the primary threats in an explosive event. Cabin penetration crushes occupants, damaging the lower body. Acceleration causes death at high magnitudes. This investigation develops a process of designing armour that simultaneously mitigates cabin penetration and acceleration. The hybrid cellular automaton (HCA) method of topology optimization has proven efficient and robust in problems involving large, plastic deformations such as crash impact. Here HCA is extended to the design of armour under blast loading. The ability to distribute two metallic phases, as opposed to one material and void, is also added. The blast wave energy transforms on impact into internal energy (IE) inside the solid medium. Maximum attenuation occurs with maximized IE. The resulting structures show HCA's potential for designing blast mitigating armour structures.

Multiscale modeling, coarse-graining and shock wave computer simulationsin materials science

Directory of Open Access Journals (Sweden)

Martin O. Steinhauser

2017-12-01

Full Text Available My intention in this review article is to briefly discuss several major topics of presentdaycomputational materials science in order to show their importance for state-of-the-art materialsmodeling and computer simulation. The topics I discuss are multiscale modeling approaches forhierarchical systems such as biological macromolecules and related coarse-graining techniques, whichprovide an effcient means to investigate systems on the mesoscale, and shock wave physics whichhas many important and interesting multi- and interdisciplinary applications in research areas wherephysics, biology, chemistry, computer science, medicine and even engineering meet. In fact, recently,as a new emerging field, the use of coarse-grained approaches for the simulation of biologicalmacromolecules such as lipids and bilayer membranes and the investigation of their interaction withshock waves has become very popular. This emerging area of research may contribute not only toan improved understanding of the microscopic details of molecular self-assembly but may also leadto enhanced medical tumor treatments which are based on the destructive effects of High IntensityFocused Ultrasound (HIFU or shock waves when interacting with biological cells and tissue; theseare treatments which have been used in medicine for many years, but which are not well understoodfrom a fundamental physical point of view.

Shock wave interaction with turbulence: Pseudospectral simulations

International Nuclear Information System (INIS)

Buckingham, A.C.

1986-01-01

Shock waves amplify pre-existing turbulence. Shock tube and shock wave boundary layer interaction experiments provide qualitative confirmation. However, shock pressure, temperature, and rapid transit complicate direct measurement. Computational simulations supplement the experimental data base and help isolate the mechanisms responsible. Simulations and experiments, particularly under reflected shock wave conditions, significantly influence material mixing. In these pseudospectral Navier-Stokes simulations the shock wave is treated as either a moving (tracked or fitted) domain boundary. The simulations assist development of code mix models. Shock Mach number and pre-existing turbulence intensity initially emerge as key parameters. 20 refs., 8 figs

International Shock-Wave Database: Current Status

Science.gov (United States)

Levashov, Pavel

2013-06-01

Shock-wave and related dynamic material response data serve for calibrating, validating, and improving material models over very broad regions of the pressure-temperature-density phase space. Since the middle of the 20th century vast amount of shock-wave experimental information has been obtained. To systemize it a number of compendiums of shock-wave data has been issued by LLNL, LANL (USA), CEA (France), IPCP and VNIIEF (Russia). In mid-90th the drawbacks of the paper handbooks became obvious, so the first version of the online shock-wave database appeared in 1997 (http://www.ficp.ac.ru/rusbank). It includes approximately 20000 experimental points on shock compression, adiabatic expansion, measurements of sound velocity behind the shock front and free-surface-velocity for more than 650 substances. This is still a useful tool for the shock-wave community, but it has a number of serious disadvantages which can't be easily eliminated: (i) very simple data format for points and references; (ii) minimalistic user interface for data addition; (iii) absence of history of changes; (iv) bad feedback from users. The new International Shock-Wave database (ISWdb) is intended to solve these and some other problems. The ISWdb project objectives are: (i) to develop a database on thermodynamic and mechanical properties of materials under conditions of shock-wave and other dynamic loadings, selected related quantities of interest, and the meta-data that describes the provenance of the measurements and material models; and (ii) to make this database available internationally through the Internet, in an interactive form. The development and operation of the ISWdb is guided by an advisory committee. The database will be installed on two mirrored web-servers, one in Russia and the other in USA (currently only one server is available). The database provides access to original experimental data on shock compression, non-shock dynamic loadings, isentropic expansion, measurements of sound

Simulations and measurements on muzzle blast mitigation with sound absorbing barriers

NARCIS (Netherlands)

Eerden, F.J.M. van der; Berg, F.H.A. van den

2012-01-01

Environmental research is ongoing to predict and to mitigate the noise impact of heavy weapons or explosives. In the densely populated area of the Netherlands this is of particular interest for the Ministry of Defence as the shock waves can propagate over large distances. In this research program

Adaptive mesh refinement for shocks and material interfaces

Energy Technology Data Exchange (ETDEWEB)

Dai, William Wenlong [Los Alamos National Laboratory

2010-01-01

There are three kinds of adaptive mesh refinement (AMR) in structured meshes. Block-based AMR sometimes over refines meshes. Cell-based AMR treats cells cell by cell and thus loses the advantage of the nature of structured meshes. Patch-based AMR is intended to combine advantages of block- and cell-based AMR, i.e., the nature of structured meshes and sharp regions of refinement. But, patch-based AMR has its own difficulties. For example, patch-based AMR typically cannot preserve symmetries of physics problems. In this paper, we will present an approach for a patch-based AMR for hydrodynamics simulations. The approach consists of clustering, symmetry preserving, mesh continuity, flux correction, communications, management of patches, and load balance. The special features of this patch-based AMR include symmetry preserving, efficiency of refinement across shock fronts and material interfaces, special implementation of flux correction, and patch management in parallel computing environments. To demonstrate the capability of the AMR framework, we will show both two- and three-dimensional hydrodynamics simulations with many levels of refinement.

Shock modification and chemistry and planetary geologic processes

International Nuclear Information System (INIS)

Boslough, M.S.

1991-01-01

This paper brings the rapid advances on shock processing of materials to the attention of Earth scientists, and to put these advances in the context of planetary geologic processes. Most of the recent research in this area has been directed at materials modification an synthesis, and the information gained has direct relevance to shock effects in nature. Research on various types of shock modification and chemistry in both naturally and experimentally shocked rocks and minerals is reviewed, and where appropriate their significance to planetary processes is indicated. As a case study, the surface of Mars is suggested as a place where conditions are optimal for shock processing to be a dominant factor. The various mechanisms of shock modification, activation, synthesis and decomposition are all proposed as major contributors to the evolution of chemical, mineralogical, and physical properties of the Martian regolith

The impacts of oil price shocks on stock market volatility: Evidence from the G7 countries

International Nuclear Information System (INIS)

Bastianin, Andrea; Conti, Francesca; Manera, Matteo

2016-01-01

We study the effects of crude oil price shocks on the stock market volatility of the G7 countries. We identify the causes underlying oil price shocks and gauge the impacts that oil supply and oil demand innovations have on financial volatility. We show that stock market volatility does not respond to oil supply shocks. On the contrary, demand shocks impact significantly on the volatility of the G7 stock markets. Our results suggest that economic policies and financial regulation activities designed to mitigate the adverse effects of unexpected oil price movements should be designed by looking at the source of the oil price shocks. - Highlights: • Effects of oil price shocks on the stock market volatility of the G7 countries. • Econometric identification of the different causes of oil shocks. • Stock market volatility does not respond to oil supply shocks. • Demand shocks impact significantly on stock market volatility. • Policy measures should be designed by considering the source of oil shocks.

Banking System Shocks and REIT Performance

OpenAIRE

Olliges, Jan-Willem; Raudszus, Malte H.; Mueller, Glenn R.

2013-01-01

The purpose of this study is to directly contrast the REIT market’s stock return response to bank failures versus bank bailouts. The non-negativity constraints of the GARCH model measuring risk dynamics are mitigated by the use of the EGARCH model. EGARCH accounts for non-symmetrical effects of risk adjustments in response to return shocks. Previous research shows that bank failures cause a positive abnormal return effect for REITs. This confirms the expectation that during crises, market par...

Maybe Next Month? Temperature Shocks, Climate Change, and Dynamic Adjustments in Birth Rates

OpenAIRE

Barreca, Alan I.; Deschenes, Olivier; Guldi, Melanie

2015-01-01

Dynamic adjustments could be a useful strategy for mitigating the costs of acute environmental shocks when timing is not a strictly binding constraint. To investigate whether such adjustments could apply to fertility, we estimate the effects of temperature shocks on birth rates in the United States between 1931 and 2010. Our innovative approach allows for presumably random variation in the distribution of daily temperatures to affect birth rates up to 24 months into the future. We find that a...

Shock physics with the nova laser for ICF applications. Revision 1

International Nuclear Information System (INIS)

Hammel, B.A.; Cauble, R.; Celliers, P.

1995-01-01

The physics of high pressure shocks plays a central role in Inertial Confinement Fusion (ICF). In indirect drive ICF, x-rays from a gold cavity (hohlraum) are used to ablatively drive a series of high pressure shocks into a spherical target (capsule). These shocks converge at the center, compressing the fuel and forming a hot dense core. The target performance, such as peak fuel density and temperature and neutron yield, depends critically on hock timing, and material compressibility. Accurate predictions of NIF target performance depends critically on shock timing and material compressibility. Current measurement techniques enable us to accurately determine shock timing in planar samples of abator material as a function of laser drive. Although this technique does not separately address uncertainties in material EOS and opacity, it does allow us to tune the laser drive until the desired shock timing is achieved. Experiments to directly address the EOS of D 2 ice are planned to further increase the margin for ignition in current target designs

Effect of nano-ZrO2 addition on microstructure, mechanical property and thermal shock behaviour of dense chromic oxide refractory material

International Nuclear Information System (INIS)

Lu, Lixia; Ding, Chunhui; Zhanga, Chi; Yanga, De'an; Di, Lizhi

2015-01-01

To obtain a good performance hot-face lining material in gasifier, nano-ZrO 2 , up to 5 wt %, was added into chromic oxide powder with 3 wt % TiO 2 followed by sintering at 1500°C for 2.5 h. The effect of nano-ZrO 2 addition on microstructure, mechanical property and thermal shock behaviour was studied. ZrO 2 promoted densification at contents higher than 1 wt %. Microcracks and phase transformation toughened the dense chromic oxide refractory material. The main reason for decrease of strength was the existence microcracks in specimens and weakening of intergranular fracture. Dense chromic oxide refractory material with 2∼3 wt % nano-ZrO 2 possessed good densification, uniform microstructure, normal mechanical property and proper thermal shock resistance. The rupture strength retention ratio was nearly twice than that of chromic oxide material without ZrO 2 after three cycles of quenching test from 950°C to cold water. (author)

Sandia Laboratories technical capabilities: materials and processes

International Nuclear Information System (INIS)

Lundergan, C.D.; Mead, P.L.

1977-08-01

Materials and process activities have emphasized the balance between research and development necessary to provide materials compatible with the extreme environments and performance requirements associated with nuclear ordnance. Specific technical areas which have continuing emphasis include metallurgy, composites, surface characterization and thin films, polymers, ceramics, and high-temperature characterization. Complete processing and fabrication facilities assure the capability for early evaluation and use of tailored materials. Efforts are focused on material applications involving structural and electronic materials, thermal and electrical insulation, radiation shields, and shock mitigation. Key elements in these efforts are functionability, reliability, and longevity. This interdisciplinary approach to scientific materials engineering results from the recognition that many disciplines are required to understand, characterize, and apply materials, and from the fact that material design is an essential element in meeting the objectives of quality, functionality, and life. In effect, the responsibility of a materials group extends beyond the development of a material into the understanding and description of its behavior in the extreme environments to which it will be subjected

Shock wave focusing in water inside convergent structures

Directory of Open Access Journals (Sweden)

C Wang

2016-09-01

Full Text Available Experiments on shock focusing in water-filled convergent structures have been performed. A shock wave in water is generated by means of a projectile, launched from a gas gun, which impacts a water-filled convergent structure. Two types of structures have been tested; a bulk material and a thin shell structure. The geometric shape of the convergent structures is given by a logarithmic spiral, and this particular shape is chosen because it maximizes the amount of energy reaching the focal region. High-speed schlieren photography is used to visualize the shock dynamics during the focusing event. Results show that the fluid-structure interaction between the thin shell structure and the shock wave in the water is different from that of a bulk structure; multiple reflections of the shock wave inside the thin shell are reflected back into the water, thus creating a wave train, which is not observed for shock focusing in a bulk material.

Plasma facing materials performance under ITER-relevant mitigated disruption photonic heat loads

Science.gov (United States)

Klimov, N. S.; Putrik, A. B.; Linke, J.; Pitts, R. A.; Zhitlukhin, A. M.; Kuprianov, I. B.; Spitsyn, A. V.; Ogorodnikova, O. V.; Podkovyrov, V. L.; Muzichenko, A. D.; Ivanov, B. V.; Sergeecheva, Ya. V.; Lesina, I. G.; Kovalenko, D. V.; Barsuk, V. A.; Danilina, N. A.; Bazylev, B. N.; Giniyatulin, R. N.

2015-08-01

PFMs (Plasma-facing materials: ITER grade stainless steel, beryllium, and ferritic-martensitic steels) as well as deposited erosion products of PFCs (Be-like, tungsten, and carbon based) were tested in QSPA under photonic heat loads relevant to those expected from photon radiation during disruptions mitigated by massive gas injection in ITER. Repeated pulses slightly above the melting threshold on the bulk materials eventually lead to a regular, "corrugated" surface, with hills and valleys spaced by 0.2-2 mm. The results indicate that hill growth (growth rate of ∼1 μm per pulse) and sample thinning in the valleys is a result of melt-layer redistribution. The measurements on the 316L(N)-IG indicate that the amount of tritium absorbed by the sample from the gas phase significantly increases with pulse number as well as the modified layer thickness. Repeated pulses significantly below the melting threshold on the deposited erosion products lead to a decrease of hydrogen isotopes trapped during the deposition of the eroded material.

Plasma facing materials performance under ITER-relevant mitigated disruption photonic heat loads

Energy Technology Data Exchange (ETDEWEB)

Klimov, N.S., E-mail: klimov@triniti.ru [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, Troitsk, Moscow 142190 (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoye shosse 31, Moscow 115409 (Russian Federation); Putrik, A.B. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, Troitsk, Moscow 142190 (Russian Federation); Linke, J. [Forschungszentrum Jülich GmbH, EURATOM Association, Jülich D-52425 (Germany); Pitts, R.A. [Karlsruhe Institute of Technology, P.O. Box 3640, Karlsruhe 76021 (Germany); Zhitlukhin, A.M. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, Troitsk, Moscow 142190 (Russian Federation); Kuprianov, I.B. [Bochvar Institute, ul. Rogova, 5a, Moscow 123098 (Russian Federation); Spitsyn, A.V. [NRC «Kurchatov Institute», Akademika Kurchatova pl., 1, Moscow 123182 (Russian Federation); Ogorodnikova, O.V. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoye shosse 31, Moscow 115409 (Russian Federation); Podkovyrov, V.L.; Muzichenko, A.D. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, Troitsk, Moscow 142190 (Russian Federation); Ivanov, B.V.; Sergeecheva, Ya.V.; Lesina, I.G. [Bochvar Institute, ul. Rogova, 5a, Moscow 123098 (Russian Federation); Kovalenko, D.V.; Barsuk, V.A.; Danilina, N.A. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, Troitsk, Moscow 142190 (Russian Federation); Bazylev, B.N. [Karlsruhe Institute of Technology, P.O. Box 3640, Karlsruhe 76021 (Germany); Giniyatulin, R.N. [Efremov Institute, Doroga na Metallostroy, 3 bld., Metallostroy, Saint-Petersburg 196641 (Russian Federation)

2015-08-15

PFMs (Plasma-facing materials: ITER grade stainless steel, beryllium, and ferritic–martensitic steels) as well as deposited erosion products of PFCs (Be-like, tungsten, and carbon based) were tested in QSPA under photonic heat loads relevant to those expected from photon radiation during disruptions mitigated by massive gas injection in ITER. Repeated pulses slightly above the melting threshold on the bulk materials eventually lead to a regular, “corrugated” surface, with hills and valleys spaced by 0.2–2 mm. The results indicate that hill growth (growth rate of ∼1 μm per pulse) and sample thinning in the valleys is a result of melt-layer redistribution. The measurements on the 316L(N)-IG indicate that the amount of tritium absorbed by the sample from the gas phase significantly increases with pulse number as well as the modified layer thickness. Repeated pulses significantly below the melting threshold on the deposited erosion products lead to a decrease of hydrogen isotopes trapped during the deposition of the eroded material.

Glovebox-contained forty-millimeter gun system for the study of one-dimensional shock waves in toxic materials

International Nuclear Information System (INIS)

Honodel, C.A.

1975-01-01

A new gun system is being constructed at the Lawrence Livermore Laboratory for studies of the behavior of toxic materials under shock-loaded conditions. Due to the extreme toxicity of some materials, such as plutonium, the entire gun system must be enclosed in gloveboxes. Some of the experimental requirements that affected the design of the system, various diagnostic techniques that will be employed with the system, and some details of the final design that is presently under assembly are presented

The structure of steady shock waves in porous metals

Science.gov (United States)

Czarnota, Christophe; Molinari, Alain; Mercier, Sébastien

2017-10-01

The paper aims at developing an understanding of steady shock wave propagation in a ductile metallic material containing voids. Porosity is assumed to be less than 0.3 and voids are not connected (foams are not considered). As the shock wave is traveling in the porous medium, the voids are facing a rapid collapse. During this dynamic compaction process, material particles are subjected to very high acceleration in the vicinity of voids, thus generating acceleration forces at the microscale that influence the overall response of the porous material. Analyzing how stationary shocks are influenced by these micro-inertia effects is the main goal of this work. The focus is essentially on the shock structure, ignoring oscillatory motion of pores prevailing at the tail of the shock wave. Following the constitutive framework developed by Molinari and Ravichandran (2004) for the analysis of steady shock waves in dense metals, an analytical approach of steady state propagation of plastic shocks in porous metals is proposed. The initial void size appears as a characteristic internal length that scales the overall dynamic response, thereby contributing to the structuring of the shock front. This key feature is not captured by standard damage models where the porosity stands for the single damage parameter with no contribution of the void size. The results obtained in this work provide a new insight in the fundamental understanding of shock waves in porous media. In particular, a new scaling law relating the shock width to the initial void radius is obtained when micro-inertia effects are significant.

Criticality conditions of heterogeneous energetic materials under shock loading

Science.gov (United States)

Nassar, Anas; Rai, Nirmal Kumar; Sen, Oishik; Udaykumar, H. S.

2017-06-01

Shock interaction with the microstructural heterogeneities of energetic materials can lead to the formation of locally heated regions known as hot spots. These hot spots are the potential sites where chemical reaction may be initiated. However, the ability of a hot spot to initiate chemical reaction depends on its size, shape and strength (temperature). Previous study by Tarver et al. has shown that there exists a critical size and temperature for a given shape (spherical, cylindrical, and planar) of the hot spot above which reaction initiation is imminent. Tarver et al. assumed a constant temperature variation in the hot spot. However, the meso-scale simulations show that the temperature distribution within a hot spot formed from processes such as void collapse is seldom constant. Also, the shape of a hot spot can be arbitrary. This work is an attempt towards development of a critical hot spot curve which is a function of loading strength, duration and void morphology. To achieve the aforementioned goal, mesoscale simulations are conducted on porous HMX material. The process is repeated for different loading conditions and void sizes. The hot spots formed in the process are examined for criticality depending on whether they will ignite or not. The metamodel is used to obtain criticality curves and is compared with the critical hot spot curve of Tarver et al.

Direct measurement technique for shock wave velocity with irradiation drive

International Nuclear Information System (INIS)

Wang Feng; Peng Xiaoshi; Liu Shenye; Jiang Xiaohua; Ding Yongkun

2011-01-01

According to the ionization mechanism of transparent material under super high pressure, the direct diagnosis method of shock wave has been analyzed. With the Drude free electron model, the reflectivity difference of shock wave front under different pressures was analyzed. The blank effect in the detector was studied, which is caused by the X-ray ionization of transparent material, after analyzing the reflectivity data in space-time scale. The experiment shows that the beginning point and duration of blank effect are consistent with the start point and duration of laser pulse, respectively. And the reflectivity of shock wave front is about 35% when the shock velocity is 32 km/s. The reason and solution for blank effect was presented. The formula to calculate the shock wave velocity in transparent material was also deduced and verified. (authors)

Evaluating the Mechanism of Oil Price Shocks and Fiscal Policy Responses in the Malaysian Economy

International Nuclear Information System (INIS)

Bekhet, Hussain A; Yusoff, Nora Yusma Mohamed

2013-01-01

The paper aims to explore the symmetric impact of oil price shock on economy, to understand its mechanism channel and how fiscal policy response towards it. The Generalized Impulse Response Function and Variance Decomposition under the VAR methodology were employed. The empirical findings suggest that symmetric oil price shock has a positive and direct impact on oil revenue and government expenditure. However, the real GDP is vulnerable in a short-term but not in the long term period. These results would confirm that fiscal policy is the main mechanism channel that mitigates the adverse effects oil price shocks to the economy.

Evaluating the Mechanism of Oil Price Shocks and Fiscal Policy Responses in the Malaysian Economy

Science.gov (United States)

Bekhet, Hussain A.; Yusoff, Nora Yusma Mohamed

2013-06-01

The paper aims to explore the symmetric impact of oil price shock on economy, to understand its mechanism channel and how fiscal policy response towards it. The Generalized Impulse Response Function and Variance Decomposition under the VAR methodology were employed. The empirical findings suggest that symmetric oil price shock has a positive and direct impact on oil revenue and government expenditure. However, the real GDP is vulnerable in a short-term but not in the long term period. These results would confirm that fiscal policy is the main mechanism channel that mitigates the adverse effects oil price shocks to the economy.

Converging shocks in elastic-plastic solids.

Science.gov (United States)

Ortega, A López; Lombardini, M; Hill, D J

2011-11-01

We present an approximate description of the behavior of an elastic-plastic material processed by a cylindrically or spherically symmetric converging shock, following Whitham's shock dynamics theory. Originally applied with success to various gas dynamics problems, this theory is presently derived for solid media, in both elastic and plastic regimes. The exact solutions of the shock dynamics equations obtained reproduce well the results obtained by high-resolution numerical simulations. The examined constitutive laws share a compressible neo-Hookean structure for the internal energy e=e(s)(I(1))+e(h)(ρ,ς), where e(s) accounts for shear through the first invariant of the Cauchy-Green tensor, and e(h) represents the hydrostatic contribution as a function of the density ρ and entropy ς. In the strong-shock limit, reached as the shock approaches the axis or origin r=0, we show that compression effects are dominant over shear deformations. For an isothermal constitutive law, i.e., e(h)=e(h)(ρ), with a power-law dependence e(h) is proportional to ρ(α), shock dynamics predicts that for a converging shock located at r=R(t) at time t, the Mach number increases as M is proportional to [log(1/R)](α), independently of the space index s, where s=2 in cylindrical geometry and 3 in spherical geometry. An alternative isothermal constitutive law with p(ρ) of the arctanh type, which enforces a finite density in the strong-shock limit, leads to M is proportional to R(-(s-1)) for strong shocks. A nonisothermal constitutive law, whose hydrostatic part e(h) is that of an ideal gas, is also tested, recovering the strong-shock limit M is proportional to R(-(s-1)/n(γ)) originally derived by Whitham for perfect gases, where γ is inherently related to the maximum compression ratio that the material can reach, (γ+1)/(γ-1). From these strong-shock limits, we also estimate analytically the density, radial velocity, pressure, and sound speed immediately behind the shock. While the

Constitutive modeling of shock response of PTFE

Energy Technology Data Exchange (ETDEWEB)

Brown, Eric N [Los Alamos National Laboratory; Reanyansky, Anatoly D [DSTO, AUSTRALIA; Bourne, Neil K [AWE, UK; Millett, Jeremy C F [AWE, UK

2009-01-01

The PTFE (polytetrafluoroethylene) material is complex and attracts attention of the shock physics researchers because it has amorphous and crystalline components. In turn, the crystalline component has four known phases with the high pressure transition to phase III. At the same time, as has been recently studied using spectrometry, the crystalline region is growing with load. Stress and velocity shock-wave profiles acquired recently with embedded gauges demonstrate feature that may be related to impedance mismatches between the regions subjected to some transitions resulting in density and modulus variations. We consider the above mentioned amorphous-to-crystalline transition and the high pressure Phase II-to-III transitions as possible candidates for the analysis. The present work utilizes a multi-phase rate sensitive model to describe shock response of the PTFE material. One-dimensional experimental shock wave profiles are compared with calculated profiles with the kinetics describing the transitions. The objective of this study is to understand the role of the various transitions in the shock response of PTFE.

Condensed matter at high shock pressures

International Nuclear Information System (INIS)

Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Radousky, H.B.; Hamilton, D.

1985-01-01

Experimental techniques are described for shock waves in liquids: Hugoniot equation-of-state, shock temperature and emission spectroscopy, electrical conductivity, and Raman spectroscopy. Experimental data are reviewed and presented in terms of phenomena that occur at high densities and temperatures in shocked He, Ar, N 2 , CO, SiO 2 -aerogel, H 2 O, and C 6 H 6 . The superconducting properties of Nb metal shocked to 100 GPa (1 Mbar) and recovered intact are discussed in terms of prospects for synthesizing novel, metastable materials. Ultrahigh pressure data for Cu is reviewed in the range 0.3 to 6TPa (3 to 60 Mbar). 56 refs., 9 figs., 1 tab

Shock characterization of an ultra-high strength concrete

International Nuclear Information System (INIS)

Erzar, B.; Pontiroli, C.; Buzaud, E.

2016-01-01

Nowadays, the design of protective structures may imply ultra-high performance concretes. These materials present a compressive strength 5 times higher than standard concretes. However, few reliable data on the shock response of such materials are available in the literature. Thus, a characterization of an ultra-high strength concrete has been conducted by means of hydrostatic and triaxial tests in the quasi-static regime, and plate impact experiments for shock response. Data have been gathered up to 6 GPa and a simple modelling approach has been applied to get a reliable representation of the shock compression of this concrete. (authors)

Empirical Model Development for Predicting Shock Response on Composite Materials Subjected to Pyroshock Loading

Science.gov (United States)

Gentz, Steven J.; Ordway, David O; Parsons, David S.; Garrison, Craig M.; Rodgers, C. Steven; Collins, Brian W.

2015-01-01

The NASA Engineering and Safety Center (NESC) received a request to develop an analysis model based on both frequency response and wave propagation analyses for predicting shock response spectrum (SRS) on composite materials subjected to pyroshock loading. The model would account for near-field environment (approx. 9 inches from the source) dominated by direct wave propagation, mid-field environment (approx. 2 feet from the source) characterized by wave propagation and structural resonances, and far-field environment dominated by lower frequency bending waves in the structure. This report documents the outcome of the assessment.

Mitigation of Ground Vibration due to Collapse of a Large-Scale Cooling Tower with Novel Application of Materials as Cushions

Directory of Open Access Journals (Sweden)

Feng Lin

2017-01-01

Full Text Available Ground vibration induced by the collapse of large-scale cooling towers in nuclear power plants (NPPs has recently been realized as a potential secondary disaster to adjacent nuclear-related facilities with demands for vibration mitigation. The previous concept to design cooling towers and nuclear-related facilities operating in a containment as isolated components in NPPs is inappropriate in a limited site which is the cases for inland NPPs in China. This paper presents a numerical study on the mitigation of ground vibration in a “cooling tower-soil-containment” system via a novel application of two materials acting as cushions underneath cooling towers, that is, foamed concrete and a “tube assembly.” Comprehensive “cooling tower-cushion-soil” models were built with reasonable cushion material models. Computational cases were performed to demonstrate the effect of vibration mitigation using seven earthquake waves. Results found that collapse-induced ground vibrations at a point with a distance of 300 m were reduced in average by 91%, 79%, and 92% in radial, tangential, and vertical directions when foamed concrete was used, and the vibrations at the same point were reduced by 53%, 32%, and 59% when the “tube assembly” was applied, respectively. Therefore, remarkable vibration mitigation was achieved in both cases to enhance the resilience of the “cooling tower-soil-containment” system against the secondary disaster.

Kidney damage in extracorporeal shock wave lithotripsy: a numerical approach for different shock profiles.

Science.gov (United States)

Weinberg, Kerstin; Ortiz, Michael

2009-08-01

In shock-wave lithotripsy--a medical procedure to fragment kidney stones--the patient is subjected to hypersonic waves focused at the kidney stone. Although this procedure is widely applied, the physics behind this medical treatment, in particular the question of how the injuries to the surrounding kidney tissue arise, is still under investigation. To contribute to the solution of this problem, two- and three-dimensional numerical simulations of a human kidney under shock-wave loading are presented. For this purpose a constitutive model of the bio-mechanical system kidney is introduced, which is able to map large visco-elastic deformations and, in particular, material damage. The specific phenomena of cavitation induced oscillating bubbles is modeled here as an evolution of spherical pores within the soft kidney tissue. By means of large scale finite element simulations, we study the shock-wave propagation into the kidney tissue, adapt unknown material parameters and analyze the resulting stress states. The simulations predict localized damage in the human kidney in the same regions as observed in animal experiments. Furthermore, the numerical results suggest that in first instance the pressure amplitude of the shock wave impulse (and not so much its exact time-pressure profile) is responsible for damaging the kidney tissue.

Attenuation of shock waves in copper and stainless steel

International Nuclear Information System (INIS)

Harvey, W.B.

1986-06-01

By using shock pins, data were gathered on the trajectories of shock waves in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). Shock pressures were generated in these materials by impacting the appropriate target with thin (approx.1.5 mm) flying plates. The flying plates in these experiments were accelerated to high velocities (approx.4 km/s) by high explosives. Six experiments were conducted, three using SS-304L as the target material and three experiments using OFHC-Cu as the target material. Peak shock pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak shock pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the shock wave by a following release wave was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the shock waves was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated shock trajectories to the experimental data. Based on such comparisons, the conclusion can be drawn that OFHC-Cu enters a melt phase at about 130 GPa on the principal Hugoniot. There was no sign of phase changes in the stainless-steel experiments. In order to match the observed attenuation of the shock waves in the SS-304L experiments, it was necessary to include strength effects in the calculations. It was found that the values for the parameters in the strength equations were dependent on the equation of state used in the modeling of the experiments. 66 refs., 194 figs., 77 tabs

Attenuation of shock waves in copper and stainless steel

Energy Technology Data Exchange (ETDEWEB)

Harvey, W.B.

1986-06-01

By using shock pins, data were gathered on the trajectories of shock waves in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). Shock pressures were generated in these materials by impacting the appropriate target with thin (approx.1.5 mm) flying plates. The flying plates in these experiments were accelerated to high velocities (approx.4 km/s) by high explosives. Six experiments were conducted, three using SS-304L as the target material and three experiments using OFHC-Cu as the target material. Peak shock pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak shock pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the shock wave by a following release wave was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the shock waves was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated shock trajectories to the experimental data. Based on such comparisons, the conclusion can be drawn that OFHC-Cu enters a melt phase at about 130 GPa on the principal Hugoniot. There was no sign of phase changes in the stainless-steel experiments. In order to match the observed attenuation of the shock waves in the SS-304L experiments, it was necessary to include strength effects in the calculations. It was found that the values for the parameters in the strength equations were dependent on the equation of state used in the modeling of the experiments. 66 refs., 194 figs., 77 tabs.

Energy shocks and detecting influential industries

International Nuclear Information System (INIS)

Kang, Dongsuk; Lee, Duk Hee

2017-01-01

An industry's relationship of supply and demand with the energy sector can be a critical factor in the stability of its economic performance. Furthermore, the patterns of industry dependence on energy industries can be a major characteristic of entire industrial structure. This research evaluates industries' impact scores for their overall influence on other industries and vulnerability to supply and demand shocks from the energy sector. The study utilizes a sample of Korea's industrial input–output tables from 2010 to 2012. Using a chain of complementary methodologies, this study finds that among four clusters, energy, services, and raw materials are key members that can spread energy shocks to other industries. Therefore, governments need to prepare effective energy efficiency policies for these target industries. - Highlights: • We analyze an industry's impact score of its vulnerability to energy shock and inter-industrial effects. • We utilize the sample of input-output tables in Korea from 2010 to 2012. • We implement simulation, PCA, TOPSIS, cluster analysis about energy shock and industrial trades. • Subsectors of energy, services, raw material are subject to energy shock and influential to others. • These bridge industries can be targets that require policies for effective energy efficiency.

High-order shock-fitted detonation propagation in high explosives

Science.gov (United States)

Romick, Christopher M.; Aslam, Tariq D.

2017-03-01

A highly accurate numerical shock and material interface fitting scheme composed of fifth-order spatial and third- or fifth-order temporal discretizations is applied to the two-dimensional reactive Euler equations in both slab and axisymmetric geometries. High rates of convergence are not typically possible with shock-capturing methods as the Taylor series analysis breaks down in the vicinity of discontinuities. Furthermore, for typical high explosive (HE) simulations, the effects of material interfaces at the charge boundary can also cause significant computational errors. Fitting a computational boundary to both the shock front and material interface (i.e. streamline) alleviates the computational errors associated with captured shocks and thus opens up the possibility of high rates of convergence for multi-dimensional shock and detonation flows. Several verification tests, including a Sedov blast wave, a Zel'dovich-von Neumann-Döring (ZND) detonation wave, and Taylor-Maccoll supersonic flow over a cone, are utilized to demonstrate high rates of convergence to nontrivial shock and reaction flows. Comparisons to previously published shock-capturing multi-dimensional detonations in a polytropic fluid with a constant adiabatic exponent (PF-CAE) are made, demonstrating significantly lower computational error for the present shock and material interface fitting method. For an error on the order of 10 m /s, which is similar to that observed in experiments, shock-fitting offers a computational savings on the order of 1000. In addition, the behavior of the detonation phase speed is examined for several slab widths to evaluate the detonation performance of PBX 9501 while utilizing the Wescott-Stewart-Davis (WSD) model, which is commonly used in HE modeling. It is found that the thickness effect curve resulting from this equation of state and reaction model using published values is dramatically more steep than observed in recent experiments. Utilizing the present fitting

Discrimination of Thermal versus Mechanical Effects of Shock on Rock Magnetic Properties of Spherically Shocked up to 10-160 GPa Basalt and Diabase

Science.gov (United States)

Bezaeva, N. S.; Swanson-Hysell, N.; Tikoo, S.; Badyukov, D. D.; Kars, M. A. C.; Egli, R.; Chareev, D. A.; Fairchild, L. M.

2016-12-01

Understanding how shock waves generated during hypervelocity impacts affect rock magnetic properties is key for interpreting the paleomagnetic records of lunar rocks, meteorites, and cratered planetary surfaces. Laboratory simulations of impacts show that ultra-high shocks may induce substantial post-shock heating of the target material. At high pressures (>10 GPa), shock heating occurs in tandem with mechanical effects, such as grain fracturing and creation of crystallographic defects and dislocations within magnetic grains. This makes it difficult to conclude whether shock-induced changes in the rock magnetic properties of target materials are primarily associated with mechanical or thermal effects. Here we present novel experimental methods to discriminate between mechanical and thermal effects of shock on magnetic properties and illustrate it with two examples of spherically shocked terrestrial basalt and diabase [1], which were shocked to pressures of 10 to >160 GPa, and investigate possible explanations for the observed shock-induced magnetic hardening (i.e., increase in remanent coercivity Bcr). The methods consist of i) conducting extra heating experiments at temperatures resembling those experienced during high-pressure shock events on untreated equivalents of shocked rocks (with further comparison of Bcr of shocked and heated samples) and ii) quantitative comparison of high-resolution first-order reversal curve (FORC) diagrams (field step: 0.5-0.7 mT) for shocked, heated and untreated specimens. Using this approach, we demonstrated that the shock-induced coercivity hardening in our samples is predominantly due to solid-state, mechanical effects of shock rather than alteration associated with shock heating. Indeed, heating-induced changes in Bcr in the post-shock temperature range were minor. Visual inspection of FORC contours (in addition to detailed analyses) reveals a stretching of the FORC distribution of shocked sample towards higher coercivities

Condensed matter at high shock pressures

Energy Technology Data Exchange (ETDEWEB)

Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Radousky, H.B.; Hamilton, D.

1985-07-12

Experimental techniques are described for shock waves in liquids: Hugoniot equation-of-state, shock temperature and emission spectroscopy, electrical conductivity, and Raman spectroscopy. Experimental data are reviewed and presented in terms of phenomena that occur at high densities and temperatures in shocked He, Ar, N/sub 2/, CO, SiO/sub 2/-aerogel, H/sub 2/O, and C/sub 6/H/sub 6/. The superconducting properties of Nb metal shocked to 100 GPa (1 Mbar) and recovered intact are discussed in terms of prospects for synthesizing novel, metastable materials. Ultrahigh pressure data for Cu is reviewed in the range 0.3 to 6TPa (3 to 60 Mbar). 56 refs., 9 figs., 1 tab.

Shock response of porous metals: characterization of pressure field

International Nuclear Information System (INIS)

Xu Aiguo; Zhang Guangcai; Hao Pengcheng; Dong Yinfeng; Wei Xijun; Zhu Jianshi

2012-01-01

Shock wave reaction on porous metals is numerically simulated. When the pressure threshold is low, the increasing rate of high-pressure area gives roughly the propagation velocity of the compressive waves in the porous material. and the wave front in the condensed pressure map is nearly a plane: with the increasing of pressure threshold. more low-pressure-spots appear in the high-pressure background, and neighboring spots may coalesce, consequently, the topology of the pressure Turing pattern may change. The deviation from linearity of the increasing rate of high-pressure area is a pronounced effect of porous material under shock. The stronger the initial shock, the more pronounced the porosity effects. When the initial yield of material becomes higher, the material shows more elastic behaviors and the less porous effects, compressive and tension waves propagate more quickly, and the porous material becomes less compressible. (authors)

Effects caused by thermal shocks in plasma sprayed protective coatings from materials based on Al2O3

International Nuclear Information System (INIS)

Gorski, L.; Wolski, T.; Gostynski, D.

1996-01-01

Plasma sprayed coatings from the materials based on Al 2 O 3 with addition of NiO and TiO 2 have been studied. Thermal shock resistance of these coatings has been tested on special experimental arrangement in the stream of hot and cold gases. Changes in coating microstructure has been determined by light microscopy methods. Phase transition caused by the experiments are revealed by X-ray diffraction methods. The resistance for thermal fatigue processes depends on used coatings materials. (author). 21 refs, 21 figs, 1 tab

Shock wave fabricated ceramic-metal nozzles

NARCIS (Netherlands)

Carton, E.P.; Stuivinga, M.E.C.; Keizers, H.L.J.; Verbeek, H.J.; Put, P.J. van der

1999-01-01

Shock compaction was used in the fabrication of high temperature ceramic-based materials. The materials' development was geared towards the fabrication of nozzles for rocket engines using solid propellants, for which the following metal-ceramic (cermet) materials were fabricated and tested: B4C-Ti

Computerized simulation of the mechanical behavior of wood-filled shock absorbers of radioactive materials transport casks

International Nuclear Information System (INIS)

Neumann, Martin; Wille, Frank

2011-01-01

In Germany the mechanical component inspection of transport containers for radioactive materials is performed by BAM (Bundesanstalt fuer Materialforschung und -pruefung) under consideration of national and international standards and guidelines. Experimental and calculative (analytical and numerical) techniques combined with material and/or component testing are the basis of assessment concepts according the state of the art. The authors describe the experiences of BAM concerning assessment and description of the mechanical behavior of shock absorbing components, including modeling strategies, material models, drop tests and experiment-calculation comparison. Energy absorbing components are used to reduce the impact forces at the container in case of a transport accident. In Germany wood filled thin-walled constructions are used. The deformation behavior of the wood is a main part of the calculative simulation procedures in comparison with experimental tests.

Scaling impact and shock-compression response for porous materials: Application to planetary formation

Science.gov (United States)

Jeanloz, R.

2016-12-01

A thermodynamic model based on the Mie-Grüneisen equation of state does a good job of describing the response of porous materials to impact, so can provide insights into the accretion and cohesion of planetesimals too small to be significantly held together by gravity (e.g., tens of km or less in average diameter). The model identifies an offset in Hugoniot pressure (ΔPH) due to porosity that is found to be in agreement with experimental shock-compression measurements for samples having a wide range of initial porosities. Assuming the Grüneisen parameter (γ) is proportional to volume (γ/V = constant), the relative offset in Hugoniot pressure as a function of initial porosity (φ = 1 - V0/V0por) and compression (η = 1 - V/V0) is ΔPH/PH = γ0 φ/[2(1 - φ) - γ0 (φ + η(1 - φ))] where subscripts 0 and por represent zero-pressure (non-porous) conditions and a porous sample, respectively. This additional thermal pressure at a given volume is due to the extra internal energy and corresponding temperature increase associated with collapsing pores (Fig. 1: near-identical curves for φ = 0.001 and 0.01). This result can be interpreted as indicating that upon collapse individual pores create hot spots with temperatures of order 103-104K above the background, suggesting that impact into an initially porous target can result in cohesion due to partial melting and vaporization. Moreover, the waste heat associated with pore closure far exceeds the dissipation in shock loading of non-porous material, reflecting the ability of a porous target to absorb and dissipate impact energy. The Mie-Grüneisen model along with analysis of waste heat thus provides a scaling for planetesimal impact that might explain how rock and regolith accrete into a gravitationally bound planet. Fig. 1. Porosity-induced anomaly in Hugoniot temperature per unit of porosity, shown as a function of compression for samples with initial porosity φ = 0.001 (green), 0.01 (blue) and 0.1 (gold) assuming

Optimizing thermal shock resistance of layered refractories

Energy Technology Data Exchange (ETDEWEB)

Hein, Jarno; Kuna, Meinhard [Institute of Mechanics and Fluid Dynamics, Technical University Bergakademie Freiberg, Lampadiusstrasse 4, 09599 Freiberg (Germany)

2012-06-15

Severe thermal shocks may cause critical thermal stresses and failure in refractories or ceramic materials. To increase the thermal shock resistance, layered material structures are suggested. In order to optimize properties of these alternative structures, thermo-mechanical simulations are required. In this study, a finite difference method (FDM) is used for solving the partial differential equation of heat conduction with spatially varying parameters. The optimization of the strip's thermal shock resistance is exemplarily done on a 10 layered strip subjected to constant temperature jump on the top surface. Each layer can be set with different porous Al{sub 2}O{sub 3} and MgO ceramics, whose material properties are theoretically determined. In this study, an improved optimization method is developed that consists of a combination and sequence of Monte Carlo simulations and evolution strategies to overcome certain disadvantages of both techniques. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Shock-wave induced mechanoluminescence: A new technique for studying effects of shock pressure on crystals

Energy Technology Data Exchange (ETDEWEB)

Chandra, B.P.; Parganiha, S.; Sonwane, V.D. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India); Chandra, V.K. [Department of Electrical and Electronics Engineering, Chhatrapati Shivaji Institute of Technology, Shivaji Nagar, Kolihapuri, Durg 491001, Chhattisgarh (India); Jha, Piyush, E-mail: piyushjha22@rediffmail.com [Department of Applied Physics, Raipur Institute of Technology, Chhatauna, Mandir Hasuad, Raipur 492101, Chhattisgarh (India); Baghel, R.N. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India)

2016-10-15

The impact of a projectile propelled to velocities in the range of 0.5–2.5 km/s on to a target (X-cut quartz crystal) produces shock waves travelling at velocity of nearly 10 km/s in target, in which intense mechanoluminescence (ML) pulses of microsecond duration are produced, both in compression and post-compression conditions. The piezoelectric field produced due to surface charges of fractured target, causes band bending and subsequently, the free charge carriers are generated in the respective bands and the emission of ML occurs. The ML appears after a delay time t{sub th} whose value decreases with increasing value of the shock pressure. Initially, the ML intensity increases with the shock pressure because of the creation of more surfaces; however, for higher values of the shock pressure, the ML intensity tends to attain a saturation value because of the hardening of the crystals due to the creation of small crystallites in which the creation of new surfaces becomes difficult. The ratio between peak ML intensity in the uncompressed region and the maximum ML intensity in the compressed region decreases with increasing shock pressure because more defects produced at high pressure generate higher barrier for the relaxation of blocked cracks under compression. The expressions derived for characteristics of shock-induced ML are able to explain satisfactorily the experimental results. Shock-wave velocity, shock pressure, transit time, lifetime of electrons in conduction band, etc. can be determined by the shock-induced ML.As such, the shock-induced ML provides a new optical technique for the studies of materials under shock pressure.

Study of laser-driven shock wave propagation in Plexiglas targets

International Nuclear Information System (INIS)

Dhareshwar, L.J.; Naik, P.A.; Pant, H.C.; Kaushik, T.C.

1992-01-01

An experimental study of laser-driven shock wave propagation in a transparent material such as Plexiglas using a high-speed optical shadowgraphy technique is presented in this paper. A Nd: glass laser was used to produce laser intensity in the range 10 12 -10 14 W/cm 2 on the target. Optical shadowgrams of the propagating shock front were recorded with a second-harmonic (0.53-μm) optical probe beam. Shock pressures were measured at various laser intensities, and the scaling was found to agree with the theoretically predicted value. Shock pressure values have also been obtained from a one-dimensional Lagrangian hydrodynamic simulation, and they match well with experimental results. Shadowgrams of shock fronts produced by nonuniform spatial laser beam irradiation profiles have shown complete smoothing when targets with a thin coating of a material of high atomic number such as gold were used. Shock pressures in such coated targets are also found to be considerably higher compared with those in uncoated targets. (Author)

Irradiation embrittlement mitigation

Energy Technology Data Exchange (ETDEWEB)

Torronen, K; Pelli, R; Planman, T; Valo, M [Technical Research Centre of Finland, Jyvaeskylae (Finland). Combustion and Thermal Engineering Lab.

1994-12-31

Mitigation methods for reducing the irradiation damage on pressure vessel materials are reviewed: load leakage loading schemes are commonly used in PWRs to mitigate reactor pressure vessel embrittlement; dummy assemblies have been applied in WWER 440-type and in some old western power plants, when exceptional fast embrittlement has been encountered; shielding of the pressure vessel has been developed, but is not in common use; pre-stressing the pressure vessel has been proposed for preventing PTS failures, but its applicability is not yet demonstrated. The large number of successful annealing treatments performed in WWER 440 type reactors as well as research on the effects of annealing treatments suggest applications for western PWRs. The emergency core cooling systems have been modified in WWER 440-type reactors in connection with other mitigation measures. (authors). 37 refs., 18 figs., 2 tabs.

Irradiation embrittlement mitigation

International Nuclear Information System (INIS)

Torronen, K.; Pelli, R.; Planman, T.; Valo, M.

1993-01-01

Mitigation methods for reducing the irradiation damage on pressure vessel materials are reviewed: load leakage loading schemes are commonly used in PWRs to mitigate reactor pressure vessel embrittlement; dummy assemblies have been applied in WWER 440-type and in some old western power plants, when exceptional fast embrittlement has been encountered; shielding of the pressure vessel has been developed, but is not in common use; pre-stressing the pressure vessel has been proposed for preventing PTS failures, but its applicability is not yet demonstrated. The large number of successful annealing treatments performed in WWER 440 type reactors as well as research on the effects of annealing treatments suggest applications for western PWRs. The emergency core cooling systems have been modified in WWER 440-type reactors in connection with other mitigation measures. (authors). 37 refs., 18 figs., 2 tabs

Theoretical study of the porosity effects on the shock response of graphitic materials

Directory of Open Access Journals (Sweden)

Pineau Nicolas

2015-01-01

Full Text Available In this paper we present a theoretical study of the shock compression of porous graphite by means of combined Monte Carlo and molecular dynamics simulations using the LCBOPII potential. The results show that the Hugoniostat methods can be used with “pole” properties calculated from porous models to reproduce the experimental Hugoniot of pure graphite and diamond with good accuracy. The computed shock temperatures show a sharp increase for weak shocks which we analyze as the heating associated with the closure of the initial porosity. After this initial phase, the temperature increases with shock intensity at a rate comparable to monocrystalline graphite and diamond. These simulations data can be exploited in view to build a full equation of state for use in hydrodynamic simulations.

Spall wave-profile and shock-recovery experiments on depleted uranium

International Nuclear Information System (INIS)

Hixson, R.S.; Vorthman, J.E.; Gustavsen, R.L.; Zurek, A.K.; Thissell, W.R.; Tonks, D.L.

1998-01-01

Depleted Uranium of two different purity levels has been studied to determine spall strength under shock wave loading. A high purity material with approximately 30 ppm of carbon impurities was shock compressed to two different stress levels, 37 and 53 kbar. The second material studied was uranium with about 300 ppm of carbon impurities. This material was shock loaded to three different final stress level, 37, 53, and 81 kbar. Two experimental techniques were used in this work. First, time-resolved free surface particle velocity measurements were done using a VISAR velocity interferometer. The second experimental technique used was soft recovery of samples after shock loading. These two experimental techniques will be briefly described here and VISAR results will be shown. Results of the spall recovery experiments and subsequent metallurgical analyses are described in another paper in these proceedings. copyright 1998 American Institute of Physics

Investigation of the dynamic behavior in materials submitted to sub-picosecond laser driven shock

International Nuclear Information System (INIS)

Cuq-Lelandais, Jean-Paul

2010-01-01

Laser driven shocks allow to investigate materials behavior at high strain rate and present a great interest for research and industrial applications. The latest laser technologies evolutions provide an access to shorter regimes in duration, below the picosecond. This work, which results from a collaboration between the P' institute, the PIMM laboratory and the CEA-DAM, is dedicated to the characterization of the metallic material behavior in this ultra-short mode (aluminium, tantalum), leading to extreme dynamic solicitation in the target (>10 7 s -1 ). The study includes the validation of experimental results obtained on the LULI 100 TW facility by comparison with numerical model. First, the study is orientated to the femtosecond (fs) laser-matter interaction, which is different from what happens in nanosecond regime. Indeed, the characteristic duration scale is comparable to several molecular phenomena like non-equilibrium electrons-ions states. The aim is to determine the equivalent pressure loading induced by the laser pulse on the target. Then, the shock wave propagation within the target has been studied and particularly its pressure decay, notably strong in this regime. In this configuration, the spalls observed are thin, a few μm order, and show a planar rupture morphology. The results obtained by post-mortem observation show that the spall thickness is thinner if the target thickness is reduced. The spalls are characterized by the VISAR measurement. Within the framework of dynamic damage modeling and rupture criteria dimensioning, particularly those which have been validated in the ns regime as Kanel, shots with different thicknesses have been carried out to determine the damage properties in function of strain rate and validate the parameters by prolongation to the ultra-shorts modes. Then, the study has been generalized to the 2D propagation waves, which can explain the spall diameter evolutions. Meanwhile, microscopic simulations of ultra-short laser

Shock loading influence on mechanical behavior of high purity iron

International Nuclear Information System (INIS)

Buy, Francois; Voltz, Christophe

2004-01-01

This paper proposes the analysis of shock wave effects for high purity iron. The method developed is based on the characterization of the mechanical behavior of as received and shocked material. Shock effect is generated through plate impact tests performed in the range of 4 GPa to 39 GPa on a single stage light gas gun or a powder gun. Therefore, as-received and impacted materials are characterized. A formalism proposed by J.R.Klepaczko and based on physical relations has been adopted to describe stress strain curves

A comparative study on shock compression of nanocrystalline Al and Cu: Shock profiles and microscopic views of plasticity

International Nuclear Information System (INIS)

Ma, Wen; Hou, Yong; Zhu, Wenjun

2013-01-01

Shock compressions of nanocrystalline (nc) metals Al and Cu with the same grain size and texture are studied by using molecular dynamics simulations. Results have revealed that the shock front of both Al and Cu can be divided into three stages: elastic, grain-boundary-mediated, and dislocation-mediated plastic deformation. The transition planes among these three stages are proven to be non-planar by two-dimensional shock response analysis, including local stress, shear, temperature, and atom configuration. The difference between shocked Al and Cu is that the rise rate of the elastic stage of Cu is slightly higher than that of Al, and that the shock-front width of Al is wider than Cu at the same loading conditions. For the plastic stage, the dislocation density of shocked Al is lower than Cu, and the contribution of grain-boundary-mediated plasticity to shock front and strain for nc Al is more pronounced than for nc Cu. These results are explained through intrinsic material properties and atomistic analysis of the plastic process. In the case of the shocked Al sample, partial dislocations, perfect dislocations, and twins are observed, but few evidence of perfect dislocations and twins are observed in the shocked Cu

Shock-induced modification of inorganic powders

International Nuclear Information System (INIS)

Graham, R.A.; Morosin, B.; Venturini, E.L.; Beauchamp, E.K.; Hammetter, W.F.

1984-01-01

The results of studies performed to quantify the characteristics of TiO2, ZrO2 and Si3N4 powders exposed to explosive loading and post-shock analysis are reported. The shocks were produced with plane wave generators and explosive pads impinging on steel disks, a copper recovery fixture, and then the samples. Peak pressures of 13 and 17 GPa were attained, along with 40 GPz at the center of the powder cavity. Data are provided on the changes occurring during the explosive densification and X-ray and paramagnetic studies of the products. Only fractured disks were obtained in the trials. The shock-treated materials were more free flowing than the original powders, which were fluffy. Post-shock annealing was a significant feature of the treated powders

A review of recent developments in the understanding of transonic shock buffet

Science.gov (United States)

Giannelis, Nicholas F.; Vio, Gareth A.; Levinski, Oleg

2017-07-01

Within a narrow band of flight conditions in the transonic regime, interactions between shock-waves and intermittently separated shear layers result in large amplitude, self-sustained shock oscillations. This phenomenon, known as transonic shock buffet, limits the flight envelope and is detrimental to both platform handling quality and structural integrity. The severity of this instability has incited a plethora of research to ascertain an underlying physical mechanism, and yet, with over six decades of investigation, aspects of this complex phenomenon remain inexplicable. To promote continual progress in the understanding of transonic shock buffet, this review presents a consolidation of recent investigations in the field. The paper begins with a conspectus of the seminal literature on shock-induced separation and modes of shock oscillation. The currently prevailing theories for the governing physics of transonic shock buffet are then detailed. This is followed by an overview of computational studies exploring the phenomenon, where the results of simulation are shown to be highly sensitive to the specific numerical methods employed. Wind tunnel investigations on two-dimensional aerofoils at shock buffet conditions are then outlined and the importance of these experiments for the development of physical models stressed. Research considering dynamic structural interactions in the presence of shock buffet is also highlighted, with a particular emphasis on the emergence of a frequency synchronisation phenomenon. An overview of three-dimensional buffet is provided next, where investigations suggest the governing mechanism may differ significantly from that of two-dimensional sections. Subsequently, a number of buffet suppression technologies are described and their efficacy in mitigating shock oscillations is assessed. To conclude, recommendations for the direction of future research efforts are given.

Optical Probes for Laser Induced Shocks

Science.gov (United States)

1992-03-01

target by the strong water. As the shock passes the material interface, it is pressure transients. only partially transmitted. The shock pressure is...T. Swimm , J. Appl. Phys. 61, evaporated, t1137(1987). vapor flow substantially. The coupling coefficient thus de- 3 v. A. Batanov and V. B. Fedorov...Waist-Surface Distance [mm] isurface on the drilling mechanismC Positive ( negative ) To roughly estimate the total recoil momentum positions

The use of a masticatory robot to analyze the shock absorption capacity of different restorative materials for implant prosthesis

Directory of Open Access Journals (Sweden)

M. Menini

2011-01-01

Full Text Available The aim of the present research was to measure in vitro the chewing load forces transmitted through crowns made of different prosthetic restorative materials onto the dental implant. A masticatory robot that is able to reproduce the mandibular movements and the forces exerted during mastication was used. The forces transmitted to the simulated periimplant bone during the robot mastication were analysis of variance (ANOVA was used. The zirconia and the ceramic crowns transmitted significantly greater forces (p-value < 0.0001 than the other crowns tested. Dental materials with lower elastic modulus were better able to ansorb shock from acclusal forces than more rigid materials.

On Maximally Dissipative Shock Waves in Nonlinear Elasticity

OpenAIRE

Knowles, James K.

2010-01-01

Shock waves in nonlinearly elastic solids are, in general, dissipative. We study the following question: among all plane shock waves that can propagate with a given speed in a given one-dimensional nonlinearly elastic bar, which one—if any—maximizes the rate of dissipation? We find that the answer to this question depends strongly on the qualitative nature of the stress-strain relation characteristic of the given material. When maximally dissipative shocks do occur, they propagate according t...

Multi-shocks generation and collapsing instabilities induced by competing nonlinearities

KAUST Repository

Crosta, Matteo; Trillo, Stefano; Fratalocchi, Andrea

2012-01-01

We investigate dispersive shock dynamics in materials with competing cubic-quintic nonlinearities. Whitham theory of modulation, hydrodynamic analysis and numerics demonstrate a rich physical scenario, ranging from multi-shock generation to collapse.

Undercuts by Laser Shock Forming

International Nuclear Information System (INIS)

Wielage, Hanna; Vollertsen, Frank

2011-01-01

In laser shock forming TEA-CO 2 -laser induced shock waves are used to form metal foils, such as aluminum or copper. The process utilizes an initiated plasma shock wave on the target surface, which leads to a forming of the foil. A challenge in forming technologies is the manufacturing of undercuts. By conventional forming methods these special forms are not feasible. In this article, it is presented that undercuts in the micro range can be produced by laser shock deep drawing. Different drawing die diameters, drawing die depths and the material aluminum in the thicknesses 20 and 50 μm were investigated. It will be presented that smaller die diameters facilitate undercuts compared to bigger die diameters. The phenomena can be explained by Barlow's formula. Furthermore, it is shown which maximum undercut depth at different die diameters can be reached. To this end, cross-sections of the different parameter combinations are displayed.

Laser shock wave and its applications

Science.gov (United States)

Yang, Chaojun; Zhang, Yongkang; Zhou, Jianzhong; Zhang, Fang; Feng, Aixin

2007-12-01

The technology of laser shock wave is used to not only surface modification but also metal forming. It can be divided into three parts: laser shock processing, laser shock forming (LSF) and laser peenforming(LPF). Laser shock processing as a surface treatment to metals can make engineering components have a residual compressive stress so that it obviously improves their fatigue strength and stress corrosion performances, while laser shock forming (LSF) is a novel technique that is used in plastic deformation of sheet metal recently and Laser peen forming (LPF) is another new sheet metal forming process presented in recent years. They all can be carried out by a high-power and repetition pulse Nd:Glass laser device made by Jiangsu University. Laser shock technology has characterized of ultrahigh pressure and high strain rate (10 6 - 10 7s -1). Now, for different materials, we are able to form different metals to contours and shapes and simultaneity leave their surfaces in crack-resistant compressive stress state. The results show that the technology of laser shock wave can strengthen surface property and prolong fatigue life and especially can deform metals to shapes that could not be adequately made using conventional methods. With the development of the technology of laser shock wave, the applied fields of laser will become greater and greater.

Mitigation technologies for damage induced by pressure waves in high-power mercury spallation neutron sources (1). Material surface improvement

International Nuclear Information System (INIS)

Naoe, Takashi; Futakawa, Masatoshi; Wakui, Takashi; Kogawa, Hiroyuki; Shoubu, Takahisa; Takeuchi, Hirotsugu; Kawai, Masayoshi

2008-01-01

Liquid-mercury target systems for MW-class spallation neutron sources are being developed in the world. Proton beams will be used to induce the spallation reaction. At the moment the proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by microjets and/or shock waves that are caused by cavitation bubble collapse impose pitting damage on the vessel wall. Bubble collapse behavior was observed by using a high-speed video camera, as well as simulated numerically. Localized impact due to cavitation bubble collapse was quantitatively estimated through comparison between numerical simulation and experiment. A novel surface treatment technique that consists of carburizing and nitriding processes was developed and the treatment condition was optimized to mitigate the pitting damage due to localized impacts. (author)

Laser shock peening of titanium 6-4 alloy

International Nuclear Information System (INIS)

Brar, N.S.; Hopkins, A.; Laber, M.W.

2000-01-01

Laser shock peening of titanium 6-4 has been shown to improve its high cycle fatigue life. Residual compressive stresses generated on the surface of titanium 6-4, as a result of laser shocking, have shown dramatic improvement in the performance of aircraft turbine blades. Laser shocking of titanium was carried out with a 20 ns pulse width, 50 joule pulsed laser, operated by LSP Technologies, Columbus, OH. Titanium disks, 20-mm in diameter, and ranging in thicknesses from zero (bare LiF) to 3-mm were subjected to laser shock to monitor amplitude and temporal stress profiles of the pulsed laser. Laser shock stress amplitudes on the back of titanium disks were monitored with VISAR using LiF as the window material. The peak shock stress produced in LiF (titanium thickness zero) was measured to be 16±1 GPa. The laser shock amplitude decays to about 2.7 GPa while propagating through 3-mm thick disk of titanium 6-4

Discrete Element Simulation of Elastoplastic Shock Wave Propagation in Spherical Particles

Directory of Open Access Journals (Sweden)

M. Shoaib

2011-01-01

Full Text Available Elastoplastic shock wave propagation in a one-dimensional assembly of spherical metal particles is presented by extending well-established quasistatic compaction models. The compaction process is modeled by a discrete element method while using elastic and plastic loading, elastic unloading, and adhesion at contacts with typical dynamic loading parameters. Of particular interest is to study the development of the elastoplastic shock wave, its propagation, and reflection during entire loading process. Simulation results yield information on contact behavior, velocity, and deformation of particles during dynamic loading. Effects of shock wave propagation on loading parameters are also discussed. The elastoplastic shock propagation in granular material has many practical applications including the high-velocity compaction of particulate material.

Time-resolved diffraction of shock-released SiO2 and diaplectic glass formation

International Nuclear Information System (INIS)

Gleason, A. E.; Bolme, C. A.; Lee, H. J.; Nagler, B.

2017-01-01

Understanding how rock-forming minerals transform under shock loading is critical for modeling collisions between planetary bodies, interpreting the significance of shock features in minerals and for using them as diagnostic indicators of impact conditions, such as shock pressure. To date, our understanding of the formation processes experienced by shocked materials is based exclusively on ex situ analyses of recovered samples. Formation mechanisms and origins of commonly observed mesoscale material features, such as diaplectic (i.e., shocked) glass, remain therefore controversial and unresolvable. Here in this paper we show in situ pump-probe X-ray diffraction measurements on fused silica crystallizing to stishovite on shock compression and then converting to an amorphous phase on shock release in only 2.4 ns from 33.6 GPa. Recovered glass fragments suggest permanent densification. These observations of real-time diaplectic glass formation attest that it is a back-transformation product of stishovite with implications for revising traditional shock metamorphism stages.

Molecular dynamics simulation of shock-wave loading of copper and titanium

Science.gov (United States)

Bolesta, A. V.; Fomin, V. M.

2017-10-01

At extreme pressures and temperatures common materials form new dense phases with compacted atomic arrangements. By classical molecular dynamics simulation we observe that FCC copper undergo phase transformation to BCC structure. The transition occurs under shock wave loading at the pressures above 80 GPa and corresponding temperatures above 2000 K. We calculate phase diagram, show that at these pressures and low temperature FCC phase of copper is still stable and discuss the thermodynamic reason for phase transformation at high temperature shock wave regime. Titanium forms new hexagonal phase at high pressure as well. We calculate the structure of shock wave in titanium and observe that shock front splits in three parts: elastic, plastic and phase transformation. The possibility of using a phase transition behind a shock wave with further unloading for designing nanocrystalline materials with a reduced grain size is also shown.

Physical Conditions in Shocked Interstellar Gas Interacting with the Supernova Remnant IC 443

Science.gov (United States)

Ritchey, Adam M.; Federman, Steven Robert; Jenkins, Edward B.; Caprioli, Damiano; Wallerstein, George

2018-06-01

We present the results of a detailed investigation into the physical conditions in interstellar material interacting with the supernova remnant IC 443. Our analysis is based on an examination of high-resolution HST/STIS spectra of two stars probing predominantly neutral gas located both ahead of and behind the supernova shock front. The pre-shock neutral gas is characterized by densities and temperatures typical of diffuse interstellar clouds, while the post-shock material exhibits a range of more extreme physical conditions, including high temperatures (>104 K) in some cases, which may require a sudden heating event to explain. The ionization level is enhanced in the high-temperature post-shock material, which could be the result of enhanced radiation from shocks or from an increase in cosmic-ray ionization. The gas-phase abundances of refractory elements are also enhanced in the high-pressure gas, suggesting efficient destruction of dust grains by shock sputtering. Observations of highly-ionized species at very high velocity indicate a post-shock temperature of 107 K for the hot X-ray emitting plasma of the remnant’s interior, in agreement with studies of thermal X-ray emission from IC 443.

Behavior of porous tungsten under shock compression at room temperature

International Nuclear Information System (INIS)

Dandekar, D.P.; Lamothe, R.M.

1977-01-01

This work reports the results of room-temperature shock-compression experiments on porous tungsten. The porous tungsten was fabricated by sintering 1-μm tungsten particles. The initial density of the material was 15290 kg/m 3 . Around 97% of the pores in the material were interconnected. The main features of the results are as follows: (1) porous tungsten behaves as a linear elastic material to 1.43 GPa; (2) the shock wave following the elastic precursor is unstable in the material in the stress range 1.43--2.7 GPa; (3) a stable two-wave structure is established at and above 6.4 GPa; (4) the response of porous tungsten is accurately described by the Mie-Grueneisen equation of state at stresses above 4.9 GPa, the stress at which the voids suffer a complete extinction in the material; (5) the deformations induced in the material due to shock compression are irreversible; (6) the recentered Hugoniot of porous tungsten becomes stiffer with the increasing magnitude of initial compressive stress

The Effects of Prior Cold Work on the Shock Response of Copper

Science.gov (United States)

Millett, J. C. F.; Higgins, D. L.; Chapman, D. J.; Whiteman, G.; Jones, I. P.; Chiu, Y.-L.

2018-04-01

A series of experiments have been performed to probe the effects of dislocation density on the shock response of copper. The shear strength immediately behind the shock front has been measured using embedded manganin stress gauges, whilst the post shock microstructural and mechanical response has been monitored via one-dimensional recovery experiments. Material in the half hard (high dislocation density) condition was shown to have both a higher shear strength and higher rate of change of shear strength with impact stress than its annealed (low dislocation density) counterpart. Microstructural analysis showed a much higher dislocation density in the half hard material compared to the annealed after shock loading, whilst post shock mechanical examination showed a significant degree of hardening in the annealed state with reduced, but still significant amount in the half hard state, thus showing a correlation between temporally resolved stress gauge measurements and post shock microstructural and mechanical properties.

Mars on Earth: Analog basaltic soils and particulates from Lonar Crater, India, include Deccan soil, shocked soil, reworked lithic and glassy ejecta, and both shocked and unshocked baked zones

Science.gov (United States)

Wright, S. P.

2017-12-01

"There is no perfect analog for Mars on Earth" [first line of Hipkin et al. (2013) Icarus, 261-267]. However, fieldwork and corresponding sample analyses from laboratory instrumentation (to proxy field instruments) has resulted in the finding of unique analog materials that suggest that detailed investigations of Lonar Crater, India would be beneficial to the goals of the Mars Program. These are briefly described below as Analog Processes, Materials, and Fieldwork. Analog Processes: The geologic history of Lonar Crater emulates localities on Mars with 1.) flood basaltic volcanism with interlayer development of 2.) baked zones or "boles" and 3.) soil formation. Of six flows, the lower three are aqueously altered by groundwater to produce a range of 4.) alteration products described below. The impact event 570 ka produced a range of 5.) impactites including shocked baked zones, shocked soils, and altered basalt shocked to a range of shock pressures [Kieffer et al., 1976]. Analog Materials: 65 Ma Deccan basalt contains augite and labradorite. Baked zones are higher in hematite and other iron oxides. Soil consists of calcite and organic matter. Several basalts with secondary alteration are listed here and these mirror alteration on Mars: hematite, chlorite, serpentine, zeolite, and palagonite, with varying combinations of these with primary igneous minerals. All of these materials (#1 through 4 above) are shocked to a range of shocked pressures to produce maskelynite, flowing plagioclase glass, vesiculated plagioclase glass, and complete impact melts. Shocked soils contain schlieren calcite amidst comminuted grains of augite, labradorite, and these glasses. Shocked baked zones unsurprisingly have a petrographic texture similar to hornfels, another product of contact metamorphism. Analog Fieldwork: The ejecta consists of two layers: 8 m of lithic breccia with unshocked and fractured basalts under a 1 m suevite consisting of all ranges of shock pressure described above

Gas-gun facility for shock wave research at BARC

International Nuclear Information System (INIS)

Gupta, S.C.; Jyoti, G.; Suresh, N.; Sikka, S.K.; Chidambaram, R.; Agarwal, R.G.; Roy, S.; Kakodkar, A.

1995-01-01

For carrying out shock-wave experiments on materials, we have built a 63 mm diameter gas-gun facility at our laboratory. It is capable of accelerating projectiles (about half kg in weight) to velocities up to 1 km/s using N 2 and He gases. These on impacting a target generate shock pressures up to 40 GPa, depending upon the impedance of the impactor and the target. The barrel of the gun is slotted so that a keyed projectile can be fired for combined compression- shear studies. Large samples can be shocked (about 60 mm diameter and 5-10 mm thick), with pressures lasting for a few microseconds. The gun is similar in design to the one at Washington State University. A number of diagnostic techniques have also been developed. These include measurement of projectile velocity, tilt between the impactor and the target, shock velocity in the target, and time resolved in-material stress wave histories in the shock loaded samples. Recovery capsules have also been made to retrieve shocked samples on unloading, which are then analysed using microscopic techniques like x-ray diffraction, Raman and electron microscopy. The gun has been performing well and has already been used for a few phase transition studies. (author). 73 refs., 42 figs

Barrier experiment: Shock initiation under complex loading

Energy Technology Data Exchange (ETDEWEB)

Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-01-12

The barrier experiments are a variant of the gap test; a detonation wave in a donor HE impacts a barrier and drives a shock wave into an acceptor HE. The question we ask is: What is the trade-off between the barrier material and threshold barrier thickness to prevent the acceptor from detonating. This can be viewed from the perspective of shock initiation of the acceptor subject to a complex pressure drive condition. Here we consider key factors which affect whether or not the acceptor undergoes a shock-to-detonation transition. These include the following: shock impedance matches for the donor detonation wave into the barrier and then the barrier shock into the acceptor, the pressure gradient behind the donor detonation wave, and the curvature of detonation front in the donor. Numerical simulations are used to illustrate how these factors affect the reaction in the acceptor.

Delayed Failure in a Shock Loaded Alumina

International Nuclear Information System (INIS)

Cooper, G. A.; Millett, J. C. F.; Bourne, N. K.; Dandekar, D. P.

2006-01-01

Manganin stress gauges have been used to measure the lateral stress in a shock-loaded alumina. In combination with known longitudinal stresses, these have been used to determine the shear strength of this material, behind the shock front. The two-step nature of the lateral stress traces shows a slow moving front behind the main shock, behind which shear strength undergoes a significant decrease. Results also show that this front decreases markedly in velocity as the HEL is crossed, suggesting that limited plasticity occurs during inelastic deformation. Finally, comparison of measured shear strengths with other aluminas shows a high degree of agreement

Cation disorder in shocked orthopyroxene.

Science.gov (United States)

Dundon, R. W.; Hafner, S. S.

1971-01-01

The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

Simulations of embedded lateral stress gauge profiles in shocked targets

International Nuclear Information System (INIS)

Winter, R E; Harris, E J

2008-01-01

In principle, stress gauges mounted to measure lateral stresses in a shocked matrix allow the shear strength of the material to be determined. However, interpreting the resistance profiles from lateral stress gauges is hindered by the fact that the stress field in the vicinity of the insulating layer in which the gauges are embedded can differ significantly from the stress field that would be generated in the sample if no gauge were present. A series of high resolution Eulerian hydrocode simulations have been run which suggest that the stresses in the insulating layer vary with distance and time in a way that depends on the thickness of the layer, the shock strength and the elastic and plastic properties of both the layer and the matrix. In particular, if the shock velocity in the matrix material is high the stress at a typical gauge position initially rises to a sharp peak then falls with time, but when the shock velocity in the matrix is low the stress rises relatively gradually throughout the time of interest. The shapes of the stress versus time profiles predicted by the hydrocode compare well with the results of lateral gauge experiments on several different materials. It is concluded that lateral gauges can be used to measure the dynamic strength of materials provided high resolution computer simulation is used to take account of the perturbation of the stress field in the shocked sample caused by the gauges

Influence of interface scattering on shock waves in heterogeneous solids

International Nuclear Information System (INIS)

Zhuang Shiming; Ravichandran, Guruswami; Grady, Dennis E.

2002-01-01

In heterogeneous media, the scattering due to interfaces between dissimilar materials play an important role in shock wave dissipation and dispersion. In this work the influence of interface scattering effect on shock waves was studied by impacting flyer plates onto periodically layered polycarbonate/6061 aluminum, polycarbonate/304 stainless steel and polycarbonate/glass composites. The experimental results (using VISAR and stress gauges) indicate that the rise time of the shock front decreases with increasing shock strength, and increases with increasing mechanical impedance mismatch between layers; the strain rate at the shock front increases by about the square of the shock stress. Experimental and numerical results also show that due to interface scattering effect the shock wave velocity in periodically layered composites decreases. In some cases the shock velocity of a layered heterogeneous composite can be lower than that of either of its components

Foreign Shocks, Monetary Policy, and Macroeconomic Fluctuations in a Small Open Economy: A SVAR Study of Malaysia

Directory of Open Access Journals (Sweden)

Zulkefly Abdul Karim

2016-06-01

Full Text Available This paper investigates the effect of foreign shocks upon domestic macroeconomic fluctuations and monetary policy, and examines the effectiveness of domestic monetary policy as a stabilization policy in Malaysia. Monetary policy variables (interest rate and money supply have been measured through a non-recursive structural VAR (SVAR identification scheme, which allows the monetary authority to set the interest rate and money supply after observing the current value of foreign variables, domestic output and inflation. The results show the important role of foreign shocks in influencing Malaysian monetary policy and macroeconomic variables. There is a real effect of monetary policy, that is, a positive shock in money supply increases domestic output. In contrast, a positive interest rates shock has a negative effect on domestic output growth and inflation. The effects of money supply and interest rate shocks on the exchange rate and stock prices are also consistent with standard economic theory. In addition, domestic monetary policy is able to mitigate the negative effect of external shocks upon domestic economy.

Geometrical shock dynamics for magnetohydrodynamic fast shocks

KAUST Repository

Mostert, W.; Pullin, D. I.; Samtaney, Ravi; Wheatley, V.

2016-01-01

We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

Geometrical shock dynamics for magnetohydrodynamic fast shocks

KAUST Repository

Mostert, W.

2016-12-12

We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

Blast mitigation experimental and numerical studies

CERN Document Server

2013-01-01

Presents experimental methods of material and structural response to dynamic blast loads Includes computational analysis of material and structural response to dynamic blast loads Offers mitigation measures for structures in various environments Relates lab experiments to larger field tests Features more than 150 illustrations

Two-zone elastic-plastic single shock waves in solids.

Science.gov (United States)

Zhakhovsky, Vasily V; Budzevich, Mikalai M; Inogamov, Nail A; Oleynik, Ivan I; White, Carter T

2011-09-23

By decoupling time and length scales in moving window molecular dynamics shock-wave simulations, a new regime of shock-wave propagation is uncovered characterized by a two-zone elastic-plastic shock-wave structure consisting of a leading elastic front followed by a plastic front, both moving with the same average speed and having a fixed net thickness that can extend to microns. The material in the elastic zone is in a metastable state that supports a pressure that can substantially exceed the critical pressure characteristic of the onset of the well-known split-elastic-plastic, two-wave propagation. The two-zone elastic-plastic wave is a general phenomenon observed in simulations of a broad class of crystalline materials and is within the reach of current experimental techniques.

Tunable evolutions of shock absorption and energy partitioning in magnetic granular chains

Science.gov (United States)

Leng, Dingxin; Liu, Guijie; Sun, Lingyu

2018-01-01

In this paper, we investigate the tunable characteristics of shock waves propagating in one-dimensional magnetic granular chains at various chain lengths and magnetic flux densities. According to the Hertz contact theory and Maxwell principle, a discrete element model with coupling elastic and field-induced interaction potentials of adjacent magnetic grains is proposed. We also present hard-sphere approximation analysis to describe the energy partitioning features of magnetic granular chains. The results demonstrate that, for a fixed magnetic field strength, when the chain length is greater than two times of the wave width of the solitary wave, the chain length has little effect on the output energy of the system; for a fixed chain length, the shock absorption and energy partitioning features of magnetic granular chains are remarkably influenced by varying magnetic flux densities. This study implies that the magnetic granular chain is potential to construct adaptive shock absorption components for impulse mitigation.

Shock wave science and technology reference library

CERN Document Server

2009-01-01

This book is the second of several volumes on solids in the Shock Wave Science and Technology Reference Library. These volumes are primarily concerned with high-pressure shock waves in solid media, including detonation and high-velocity impact and penetration events. Of the four extensive chapters in this volume, the first two describe the reactive behavior of condensed phase explosives, - Condensed-Phase Explosives: Shock Initiation and Detonation Phenomena (SA Sheffield and R Engelke) - First Principles Molecular Simulations of Energetic Materials at High-Pressures (F Zhang, S Alavi, and TK Woo), and the remaining two discuss the inert, mechanical response of solid materials. - Combined Compression and Shear Plane Waves (ZP Tang and JB Aidun), and - Dynamic Fragmentation of Solids (D Grady). All chapters are each self-contained, and can be read independently of each other. They offer a timely reference, for beginners as well as professional scientists and engineers, on the foundations of detonation phenomen...

Radiating shocks and condensations in flares

International Nuclear Information System (INIS)

Fisher, G.H.

1985-01-01

Rapid energy release (by either ''thick target'' (beam) or ''thermal'' models of heating) in solar flare loop models usually leads to ''chromospheric evaporation,'' the process of heating cool chromospheric material to coronal temperatures, and the resulting increase in hot soft x-ray emitting plasma. The evaporated plasma flows up into the coronal portion of the loop because of the increased pressure in the evaporated region. However, the pressure increase also leads to a number of interesting phenomena in the flare chromosphere, which will be the subject of this paper. The sudden pressure increase in the evaporated plasma initiates a downward moving ''chromospheric condensation,'' an overdense region which gradually decelerates as it accretes material and propagates into the gravitationally stratified chromosphere. Solutions to an equation of motion for this condensation shows that its motion decays after about one minute of propagation into the chromosphere. When the front of this downflowing region is supersonic relative to the atmosphere ahead of it, a radiating shock will form. If the downflow is rapid enough, the shock strength should be sufficient to excite uv radiation normally associated with the transition region, and furthermore, the radiating shock will be brighter than the transition region. These results lead to a number of observationally testable relationships between the optical and ultraviolet spectra from the condensation and radiating shock

Experimental Shock Transformation of Gypsum to Anhydrite: A New Low Pressure Regime Shock Indicator

Science.gov (United States)

Bell, Mary S.; Zolensky, Michael E.

2011-01-01

] reanalyzed the calcite and anhydrite shock wave experiments of Yang [9] using improved equations of state of porous materials and vaporized products. They determined the pressures for incipient and complete vaporization to be 32.5 and 122 GPa for anhydrite GPa which is a factor of 2 to 3 lower than reported earlier by Yang [9]. These studies are not in agreement regarding the onset of sulfate decomposition and documentation of shock effects in gypsum is incomplete.

Fundamental structure of steady plastic shock waves in metals

OpenAIRE

Molinari, A.; Ravichandran, G.

2004-01-01

The propagation of steady plane shock waves in metallic materials is considered. Following the constitutive framework adopted by R. J. Clifton [Shock Waves and the Mechanical Properties of Solids, edited by J. J. Burke and V. Weiss (Syracuse University Press, Syracuse, N.Y., 1971), p. 73] for analyzing elastic–plastic transient waves, an analytical solution of the steady state propagation of plastic shocks is proposed. The problem is formulated in a Lagrangian setting appropriate for large de...

Finite Element Modeling of Material Fatigue and Cracking Problems for Steam Power System HP Devices Exposed to Thermal Shocks

Directory of Open Access Journals (Sweden)

Pawlicki Jakub

2016-09-01

Full Text Available The paper presents a detailed analysis of the material damaging process due to low-cycle fatigue and subsequent crack growth under thermal shocks and high pressure. Finite Element Method (FEM model of a high pressure (HP by-pass valve body and a steam turbine rotor shaft (used in a coal power plant is presented. The main damaging factor in both cases is fatigue due to cycles of rapid temperature changes. The crack initiation, occurring at a relatively low number of load cycles, depends on alternating or alternating-incremental changes in plastic strains. The crack propagation is determined by the classic fracture mechanics, based on finite element models and the most dangerous case of brittle fracture. This example shows the adaptation of the structure to work in the ultimate conditions of high pressure, thermal shocks and cracking.

Absolute Hugoniot measurements from a spherically convergent shock using x-ray radiography

Science.gov (United States)

Swift, Damian C.; Kritcher, Andrea L.; Hawreliak, James A.; Lazicki, Amy; MacPhee, Andrew; Bachmann, Benjamin; Döppner, Tilo; Nilsen, Joseph; Collins, Gilbert W.; Glenzer, Siegfried; Rothman, Stephen D.; Kraus, Dominik; Falcone, Roger W.

2018-05-01

The canonical high pressure equation of state measurement is to induce a shock wave in the sample material and measure two mechanical properties of the shocked material or shock wave. For accurate measurements, the experiment is normally designed to generate a planar shock which is as steady as possible in space and time, and a single state is measured. A converging shock strengthens as it propagates, so a range of shock pressures is induced in a single experiment. However, equation of state measurements must then account for spatial and temporal gradients. We have used x-ray radiography of spherically converging shocks to determine states along the shock Hugoniot. The radius-time history of the shock, and thus its speed, was measured by radiographing the position of the shock front as a function of time using an x-ray streak camera. The density profile of the shock was then inferred from the x-ray transmission at each instant of time. Simultaneous measurement of the density at the shock front and the shock speed determines an absolute mechanical Hugoniot state. The density profile was reconstructed using the known, unshocked density which strongly constrains the density jump at the shock front. The radiographic configuration and streak camera behavior were treated in detail to reduce systematic errors. Measurements were performed on the Omega and National Ignition Facility lasers, using a hohlraum to induce a spatially uniform drive over the outside of a solid, spherical sample and a laser-heated thermal plasma as an x-ray source for radiography. Absolute shock Hugoniot measurements were demonstrated for carbon-containing samples of different composition and initial density, up to temperatures at which K-shell ionization reduced the opacity behind the shock. Here we present the experimental method using measurements of polystyrene as an example.

Introduction to Shock Waves and Shock Wave Research

Energy Technology Data Exchange (ETDEWEB)

Anderson, William Wyatt [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-02-02

M-9 and a number of other organizations at LANL and elsewhere study materials in dynamic processes. Often, this is described as “shock wave research,” but in reality is broader than is implied by that term. Most of our work is focused on dynamic compression and associated phenomena, but you will find a wide variety of things we do that, while related, are not simple compression of materials, but involve a much richer variety of phenomena. This tutorial will introduce some of the underlying physics involved in this work, some of the more common types of phenomena we study, and common techniques. However, the list will not be exhaustive by any means.

Yield strength measurement of shock-loaded metal by flyer-impact perturbation method

Science.gov (United States)

Ma, Xiaojuan; Shi, Zhan

2018-06-01

Yield strength is one of the most important physical properties of a solid material, especially far from its melting line. The flyer-impact perturbation method measures material yield strength on the basis of correlation between the yield strength under shock compression and the damping of oscillatory perturbations in the shape of a shock front passing through the material. We used flyer-impact experiments on targets with machined grooves on the impact surface of shock 6061-T6 aluminum to between 32 and 61 GPa and recorded the evolution of the shock front perturbation amplitude in the sample with electric pins. Simulations using the elastic-plastic model can be matched to the experiments, explaining well the form of the perturbation decay and constraining the yield strength of 6061-T6 aluminum to be 1.31-1.75 GPa. These results are in agreement with values obtained from reshock and release wave profiles. We conclude that the flyer-impact perturbation method is indeed a new means to measure material strength.

Design and testing of a shock absorber for a type I container

International Nuclear Information System (INIS)

Sappok, M.; Beine, B.; Rittscher, D.; Jais, M.

1994-01-01

A simple method of designing a shock absorber to protect a type B cast-iron container is developed. The results of deformation tests of the structural material (steel pipes) used for the shock absorber are presented. The accelerations and strains measured during the 9m drop tests of the container with the shock absorber are compared with the theoretical results of the calculations for the shock absorber design. ((orig.))

Distributional impacts of climate change mitigation in Indian electricity: The influence of governance

International Nuclear Information System (INIS)

Rao, Narasimha D.

2013-01-01

Studies that examine the distributional impacts of climate change mitigation policies often neglect the influence of institutions that implement these policies. This study examines the short-term consumption-side distributional impacts of expanding low-carbon electric supply in the state of Maharashtra, India with a focus on the influence of regulatory discretion in pricing. Households' welfare impacts from economy-wide electricity price shocks are simulated against a baseline that is calibrated to actual household economic and electricity service conditions, including actual electricity budgets, block tier prices and supply rationing. Industrial price impacts are propagated to households using a Leontief input–output analysis. Regulatory pricing decisions are evaluated based on social welfare metrics for economic efficiency and income inequality. The analysis reveals new linkages between climate change mitigation, electricity policy and income distribution. Low-income households can be shielded from mitigation impacts without losses in aggregate welfare to the extent that regulators can recover mitigation costs through industrial price increases. Regulators' flexibility to distribute costs across households is constrained by industrial customers' migration off the grid. Reduced supply interruptions to the rural poor from the resulting demand contraction are a potential co-benefit of mitigation. Distributional impacts, therefore, depend on other electricity policies that are driven by the political economy of the sector. - Highlights: • Indirect price increases harm most households less than residential price increases. • Regulators have flexibility to distribute mitigation costs across income groups. • Reduced supply interruptions are a potential co-benefit of mitigation

Shock behaviour of 3D carbon-carbon composite

International Nuclear Information System (INIS)

Hereil, P.-L.; Allix, O.; Gratton, M.

1997-01-01

The compressive response of a 3D carbon-carbon composite under shock wave was studied in a plate-impact configuration. Two directions of impact were achieved until a nominal value of longitudinal stress of 2.5 GPa. The measured wave profiles are consistent with previous results on 3D composites and confirm the behaviour of such materials under impact. It is shown that the initial loading is decomposed in two waves. The first one is transmitted by the longitudinal fibres, the second one corresponds to the propagation of a shock wave in the 'matrix'. Macroscopic characteristics of this material are provided. (orig.)

Therapeutic Down-Modulators of Staphylococcal Superantigen-Induced Inflammation and Toxic Shock

Directory of Open Access Journals (Sweden)

Teresa Krakauer

2010-07-01

Full Text Available Staphylococcal enterotoxin B (SEB and related superantigenic toxins are potent stimulators of the immune system and cause a variety of diseases in humans, ranging from food poisoning to toxic shock. These toxins bind directly to major histocompatibility complex (MHC class II molecules on antigen-presenting cells and specific Vb regions of T-cell receptors (TCR, resulting in hyperactivation of both monocytes/macrophages and T lymphocytes. Activated host cells produce massive amounts of proinflammatory cytokines and chemokines, activating inflammation and coagulation, causing clinical symptoms that include fever, hypotension, and shock. This review summarizes the in vitro and in vivo effects of staphylococcal superantigens, the role of pivotal mediators induced by these toxins in the pathogenic mechanisms of tissue injury, and the therapeutic agents to mitigate the toxic effects of superantigens.

Tribology Aspect of Rubber Shock Absorbers Development

Directory of Open Access Journals (Sweden)

M. Banić

2013-09-01

Full Text Available Rubber is a very flexible material with many desirable properties Which enable its broad use in engineering practice. Rubber or rubber-metal springs are widely used as anti-vibration or anti-shock components in technical systems. Rubber-metal springs are usually realized as a bonded assembly, however especially in shock absorbers, it is possible to realize free contacts between rubber and metal parts. In previous research it authors was observed that friction between rubber and metal in such case have a significant influence on the damping characteristics of shock absorber. This paper analyzes the development process of rubber or rubber-metal shock absorbers realized free contacts between the constitutive parts, starting from the design, construction, testing and operation, with special emphasis on the development of rubber-metal springs for the buffing and draw gear of railway vehicles.

Shock Waves

CERN Document Server

Jiang, Z

2005-01-01

The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.

Physics of Collisionless Shocks Space Plasma Shock Waves

CERN Document Server

Balogh, André

2013-01-01

The present book provides a contemporary systematic treatment of shock waves in high-temperature collisionless plasmas as are encountered in near Earth space and in Astrophysics. It consists of two parts. Part I develops the complete theory of shocks in dilute hot plasmas under the assumption of absence of collisions among the charged particles when the interaction is mediated solely by the self-consistent electromagnetic fields. Such shocks are naturally magnetised implying that the magnetic field plays an important role in their evolution and dynamics. This part treats both subcritical shocks, which dissipate flow energy by generating anomalous resistance or viscosity, and supercritical shocks. The main emphasis is, however, on super-critical shocks where the anomalous dissipation is insufficient to retard the upstream flow. These shocks, depending on the direction of the upstream magnetic field, are distinguished as quasi-perpendicular and quasi-parallel shocks which exhibit different behaviours, reflecti...

High-speed imaging of inhomogeneous ignition in a shock tube

Science.gov (United States)

Tulgestke, A. M.; Johnson, S. E.; Davidson, D. F.; Hanson, R. K.

2018-05-01

Homogeneous and inhomogeneous ignition of real and surrogate fuels were imaged in two Stanford shock tubes, revealing the influence of small particle fragmentation. n-Heptane, iso-octane, and Jet A were studied, each mixed in an oxidizer containing 21% oxygen and ignited at low temperatures (900-1000 K), low pressures (1-2 atm), with an equivalence ratio of 0.5. Visible images (350-1050 nm) were captured through the shock tube endwall using a high-speed camera. Particles were found to arrive near the endwalls of the shock tubes approximately 5 ms after reflection of the incident shock wave. Reflected shock wave experiments using diaphragm materials of Lexan and steel were investigated. Particles collected from the shock tubes after each experiment were found to match the material of the diaphragm burst during the experiment. Following each experiment, the shock tubes were cleaned by scrubbing with cotton cloths soaked with acetone. Particles were observed to fragment after arrival near the endwall, often leading to inhomogeneous ignition of the fuel. Distinctly more particles were observed during experiments using steel diaphragms. In experiments exhibiting inhomogeneous ignition, flames were observed to grow radially until all the fuel within the cross section of the shock tube had been consumed. The influence of diluent gas (argon or helium) was also investigated. The use of He diluent gas was found to suppress the number of particles capable of causing inhomogeneous flames. The use of He thus allowed time history studies of ignition to extend past the test times that would have been limited by inhomogeneous ignition.

Evaluation of the of thermal shock resistance of a castable containing andalusite aggregates by thermal shock cycles

International Nuclear Information System (INIS)

Garcia, G.C.R.; Santos, E.M.B.; Ribeiro, S.; Rodrigues, J.A.

2011-01-01

The thermal shock resistance of refractory materials is one of the most important characteristics that determine their performance in many applications, since abrupt and drastic differences in temperature can damage them. Resistance to thermal shock damage can be evaluated based on thermal cycles, i.e., successive heating and cooling cycles followed by an analysis of the drop in Young's modulus occurring in each cycle. The aim of this study was to evaluate the resistance to thermal shock damage in a commercial refractory concrete with andalusite aggregate. Concrete samples that were sintered at 1000 deg C and 1450 deg C for 5 hours to predict and were subjected to 30 thermal shock cycles, soaking in the furnace for 20 minutes at a temperature of 1000 deg C, and subsequent cooling in circulating water at 25 deg C. The results showed a decrease in Young's modulus and rupture around 72% for samples sintered at 1000 ° C, and 82% in sintered at 1450 ° C. The refractory sintered at 1450 deg C would show lower thermal shock resistance than the refractory sintered at 1000 deg C. (author)

Evaluation of Coagulation Profiles in Dogs with Septic Shock

OpenAIRE

YILMAZ, Zeki; YALÇIN, Ebru

2002-01-01

The aim of the this study was to observe possible changes in coagulation profiles in dogs with septic shock. A total of 30 dogs (control group n=10, test group n=20) were used as materials in this study. Although different diseases leading to septic shock were diagnosed in dogs in the test group, dogs were selected on the basis of septic shock criteria such as fever or hypothermia, hypotension, leukopenia or leukocytosis and thrombocytopenia. In addition to the results of rutine clinical and...

Shock Response of Lightweight Adobe Masonry

Science.gov (United States)

Sauer, C.; Bagusat, F.; Heine, A.; Riedel, W.

2018-04-01

The behavior of a low density and low-strength building material under shock loading is investigated. The considered material is lightweight adobe masonry characterized by a density of 1.2 g/cm3 and a quasi-static uniaxial compressive strength of 2.8 MPa. Planar-plate-impact (PPI) tests with velocities in between 295 and 950 m/s are performed in order to obtain Hugoniot data and to derive parameters for an equation of state (EOS) that captures the occurring phenomenology of porous compaction and subsequent unloading. The resulting EOS description is validated by comparing the experimental free surface velocity time curves with those obtained by numerical simulations of the performed PPI tests. The non-linear compression behavior, including the pore compaction mechanism, constitutes a main ingredient for modelling the response of adobe to blast and high-velocity impact loading. We hence present a modeling approach for lightweight adobe which can be applied to such high rate loading scenarios in future studies. In general, this work shows that PPI tests on lightweight and low-strength geological materials can be used to extract Hugoniot data despite significant material inhomogeneity. Furthermore, we demonstrate that a homogenous material model is able to numerically describe such a material under shock compression and release with a reasonable accuracy.

Value/impact analysis for evaluating alternative mitigation systems

International Nuclear Information System (INIS)

Kastenberg, W.E.; Catton, I.; Castle, J.N.; Dooley, J.L.; Hammond, R.P.

1988-01-01

Methods are developed for assessing the cost effectiveness of proposed systems and strategies for mitigating the consequences of severe nuclear accidents. Such mitigation systems consist mostly of devices for improving the ability of a reactor containment to survive such an accident and retain all radioactive materials. Value/impact analysis is applied to the system with and without mitigation, using the population dose averted by mitigation as the value of benefit, and the dollar cost of the containment improvements as the impact. Other considerations affecting such analyses include ways of monetizing public health risk, economic discounting, and the effect of interdiction policy and other post-accident recovery costs

Shock absorber in combination with a nuclear reactor core structure

International Nuclear Information System (INIS)

Housman, J.J.

1976-01-01

This invention relates to the provision of shock absorbers for use in blind control rod passages of a nuclear reactor core structure which are not subject to degradation. The shock absorber elements are made of a porous brittle carbonaceous material, a porous brittle ceramic material, or a porous brittle refractory oxide and have a void volume of between 30% and 70% of the total volume of the element for energy absorption by fracturing due to impact loading by a control rod. (UK)

Experimental and theoretical investigations of shock-induced flow of reactive porous media

Energy Technology Data Exchange (ETDEWEB)

Baer, M.R.; Graham, R.A.; Anderson, M.U. [Sandia National Labs., Albuquerque, NM (United States); Sheffield, S.A.; Gustavsen, R.L. [Los Alamos National Lab., NM (United States)

1996-11-01

In this work, the microscale processes of consolidation, deformation and reaction features of shocked porous materials are studied. Time- resolve particle velocities and stress fields associated with dispersive compaction waves are measured in gas-gun experiments. In these tests, a thin porous layer of HMX is shock-loaded at varied levels. At high impact, significant reaction is triggered by the rapid material distortion during compaction. In parallel modeling studies, continuum mixture theory is applied to describe the behavior of averaged wave-fields in heterogeneous media. One-dimensional simulations of gas-gun experiments demonstrate that the wave features and interactions with viscoelastic materials in the gauge package are well described by mixture theory, including reflected wave behavior and conditions where significant reaction is initiated. Numerical simulations of impact on a collection of discrete HMX `crystals` are also presented using shock physics analysis. Three-dimensional simulations indicate that rapid distortion occurs at material contact points; the nature of the dispersive fields includes large amplitude fluctuations of stress with wavelengths of several particle diameters. Localization of energy causes `hot-spots` due to shock focusing and plastic work as material flows into interstitial regions. These numerical experiments demonstrate that `hot-spots` are strongly influenced by multiple crystal interactions. This mesoscale study provides new insights into micromechanical behavior of heterogeneous energetic materials.

Shock-resistant scintillation detector

International Nuclear Information System (INIS)

Novak, W.P.

1979-01-01

A unique scintillation detector unit is disclosed which employs a special light transfer and reflector means that encases and protects the scintillator crystal against high g forces. The light transfer means comprises a flexible silicon rubber optical material bonded between the crystal and the optical window and having an axial thickness sufficient to allow the scintillator to move axially inside the container under high g forces without destroying the bonds. The reflector means comprises a soft elastic silicone rubber sleeve having a multiplicity of closely arranged tapered protrusions radiating toward and engaging the periphery of the scintillator crystal to cushion shocks effectively and having a reflective material, such as aluminum oxide powder, in the spaces between the protrusions. The reflector means provides improved shock absorption because of the uniform support and cushioning action of the protrusions and also provides the detector with high efficiency. The silicon rubber composition is specially compounded to include a large amount of aluminum oxide which enables the rubber to function effectively as a light reflector

Simulations of Turbulent Flows with Strong Shocks and Density Variations: Final Report

Energy Technology Data Exchange (ETDEWEB)

Sanjiva Lele

2012-10-01

The target of this SciDAC Science Application was to develop a new capability based on high-order and high-resolution schemes to simulate shock-turbulence interactions and multi-material mixing in planar and spherical geometries, and to study Rayleigh-Taylor and Richtmyer-Meshkov turbulent mixing. These fundamental problems have direct application in high-speed engineering flows, such as inertial confinement fusion (ICF) capsule implosions and scramjet combustion, and also in the natural occurrence of supernovae explosions. Another component of this project was the development of subgrid-scale (SGS) models for large-eddy simulations of flows involving shock-turbulence interaction and multi-material mixing, that were to be validated with the DNS databases generated during the program. The numerical codes developed are designed for massively-parallel computer architectures, ensuring good scaling performance. Their algorithms were validated by means of a sequence of benchmark problems. The original multi-stage plan for this five-year project included the following milestones: 1) refinement of numerical algorithms for application to the shock-turbulence interaction problem and multi-material mixing (years 1-2); 2) direct numerical simulations (DNS) of canonical shock-turbulence interaction (years 2-3), targeted at improving our understanding of the physics behind the combined two phenomena and also at guiding the development of SGS models; 3) large-eddy simulations (LES) of shock-turbulence interaction (years 3-5), improving SGS models based on the DNS obtained in the previous phase; 4) DNS of planar/spherical RM multi-material mixing (years 3-5), also with the two-fold objective of gaining insight into the relevant physics of this instability and aiding in devising new modeling strategies for multi-material mixing; 5) LES of planar/spherical RM mixing (years 4-5), integrating the improved SGS and multi-material models developed in stages 3 and 5. This final report is

Role of the calcaneal heel pad and polymeric shock absorbers in attenuation of heel strike impact.

Science.gov (United States)

Noe, D A; Voto, S J; Hoffmann, M S; Askew, M J; Gradisar, I A

1993-01-01

The capacity of the calcaneal heel pad, with and without augmentation by a polymeric shock absorbing material (Sorbothane 0050), to attenuate heel strike impulses has been studied using five fresh human cadaveric lower leg specimens. The specimens, instrumented with an accelerometer, were suspended and impacted with a hammer; a steel rod was similarly suspended and impacted. The calcaneal heel pad attenuated the peak accelerations by 80%. Attenuations of up to 93% were achieved by the shock absorbing material when tested against the steel rod; however, when tested in series with the calcaneal heel pad, the reduction in peak acceleration due to the shock absorbing material dropped to 18%. Any evaluation of the effectiveness of shock absorbing shoe materials must take into account their mechanical interaction with the body.

A Shocking Solar Nebula?

OpenAIRE

Liffman, Kurt

2009-01-01

It has been suggested that shock waves in the solar nebula formed the high temperature materials observed in meteorites and comets. It is shown that the temperatures at the inner rim of the solar nebula could have been high enough over a sufficient length of time to produce chondrules, CAIs, refractory dust grains and other high-temperature materials observed in comets and meteorites. The solar bipolar jet flow may have produced an enrichment of 16O in the solar nebula over time and the chond...

Simulations of Converging Shock Collisions for Shock Ignition

Science.gov (United States)

Sauppe, Joshua; Dodd, Evan; Loomis, Eric

2016-10-01

Shock ignition (SI) has been proposed as an alternative to achieving high gain in inertial confinement fusion (ICF) targets. A central hot spot below the ignition threshold is created by an initial compression pulse, and a second laser pulse drives a strong converging shock into the fuel. The collision between the rebounding shock from the compression pulse and the converging shock results in amplification of the converging shock and increases the hot spot pressure above the ignition threshold. We investigate shock collision in SI drive schemes for cylindrical targets with a polystyrene foam interior using radiation-hydrodynamics simulations with the RAGE code. The configuration is similar to previous targets fielded on the Omega laser. The CH interior results in a lower convergence ratio and the cylindrical geometry facilitates visualization of the shock transit using an axial X-ray backlighter, both of which are important for comparison to potential experimental measurements. One-dimensional simulations are used to determine shock timing, and the effects of low mode asymmetries in 2D computations are also quantified. LA-UR-16-24773.

Shock-jump conditions in a general medium: weak-solution approach

Science.gov (United States)

Forbes, L. K.; Krzysik, O. A.

2017-05-01

General conservation laws are considered, and the concept of a weak solution is extended to the case of an equation involving three space variables and time. Four-dimensional vector calculus is used to develop general jump conditions at a shock wave in the material. To illustrate the use of this result, jump conditions at a shock in unsteady three-dimensional compressible gas flow are presented. It is then proved rigorously that these reduce to the commonly assumed conditions in coordinates normal and tangential to the shock face. A similar calculation is also outlined for an unsteady three-dimensional shock in magnetohydrodynamics, and in a chemically reactive fluid. The technique is available for determining shock-jump conditions in quite general continuous media.

A fractographic study of cracks produced by thermal shocks in 20MnMoNi55 and comparable weld material in water environment

International Nuclear Information System (INIS)

Toerroenen, K.; Rintamaa, R.; Kemppainen, M.

1983-04-01

This report gives the results of a fractographic study of cracks produced by thermal shocks in 20MnMoNi55 and comparable weld material in water environment. The basic crack growth mechanism is shown to be by mechanical fatigue, but after some crack growth indications of environmentally assisted cyclic crack growth is seen. (author)

Measurements of the Shock Release Of Quartz and Paralyene-N

Science.gov (United States)

Hawreliak, James; Karasik, Max; Oh, Jaechul; Aglitskiy, Yefim

2017-06-01

The shock and release properties of Quartz and hydrocarbons are important to high energy density (HED) research and inertial confinement fusion (ICF) science. The bulk of HED material research studies single shock or multiple shock conditions. The challenge with measuring release properties is unlike shocks which have a single interface from which to measure the properties, the release establishes gradients in the sample. The streaked x-ray imaging capability of the NIKE laser allow the interface between quartz and CH to be measured during the release, giving measurements of the interface velocity and CH density. Here, we present experimental results from the NIKE laser where quartz and parylene-N are shock compressed to high pressure and temperature and the release state is measured through x-ray imaging. The shock state is characterized by shock front velocity measurements using VISAR and the release state is characterized by using side-on streaked x-ray radiography Work supported by DOE/NNSA.

Design of materials configurations for enhanced phononic and electronic properties

Science.gov (United States)

Daraio, Chiara

The discovery of novel nonlinear dynamic and electronic phenomena is presented for the specific cases of granular materials and carbon nanotubes. This research was conducted for designing and constructing optimized macro-, micro- and nano-scale structural configurations of materials, and for studying their phononic and electronic behavior. Variation of composite arrangements of granular elements with different elastic properties in a linear chain-of-sphere, Y-junction or 3-D configurations led to a variety of novel phononic phenomena and interesting physical properties, which can be potentially useful for security, communications, mechanical and biomedical engineering applications. Mechanical and electronic properties of carbon nanotubes with different atomic arrangements and microstructures were also investigated. Electronic properties of Y-junction configured carbon nanotubes exhibit an exciting transistor switch behavior which is not seen in linear configuration nanotubes. Strongly nonlinear materials were designed and fabricated using novel and innovative concepts. Due to their unique strongly nonlinear and anisotropic nature, novel wave phenomena have been discovered. Specifically, violations of Snell's law were detected and a new mechanism of wave interaction with interfaces between NTPCs (Nonlinear Tunable Phononic Crystals) was established. Polymer-based systems were tested for the first time, and the tunability of the solitary waves speed was demonstrated. New materials with transformed signal propagation speed in the manageable range of 10-100 m/s and signal amplitude typical for audible speech have been developed. The enhancing of the mitigation of solitary and shock waves in 1-D chains were demonstrated and a new protective medium was designed for practical applications. 1-D, 2-D and 3-D strongly nonlinear system have been investigated providing a broad impact on the whole area of strongly nonlinear wave dynamics and creating experimental basis for new

Investigation of erosion mechanisms and erosion products in divertor armour materials under conditions relevant to elms and mitigated disruptions in ITER

International Nuclear Information System (INIS)

Safronov, V.M.; Arkhipov, N.I.; Klimov, N.S.; Kovalenko, D.V.; Moskaleva, A.A.; Podkovyrov, V.L.; Toporkov, D.A.; Zhitlukhin, A.M.; Landman, I.S.; Poznyak, I.M.

2008-01-01

Carbon fibre composite (CFC) and tungsten were irradiated by intense plasma streams at plasma gun facilities MK-200UG and QSPA-T. The targets were tested by plasma loads relevant to Edge Localised Modes (ELM) and mitigated disruptions in ITER. Onset condition of material erosion and properties of erosion products have been studied

On the shock response of the magnesium alloy Elektron 675

Science.gov (United States)

Hazell, Paul; Appleby-Thomas, Gareth; Siviour, Clive; Wielewski, Euan

2011-06-01

Alloying elements such as aluminium, zinc or rare-earths allow precipitation hardening of magnesium (Mg). The low densities of such strengthened Mg alloys have led to their adoption as aerospace materials and (more recently) they are being considered as armour materials. Consequently, understanding their response to high-strain rate loading is becoming increasingly important. Here, the plate-impact technique was employed to measure longitudinal stress evolution in armour-grade wrought Mg-alloy Elektron 675 under 1D shock loading. The strength and spall behaviour was interrogated, with an estimate made of the material's Hugoniot elastic limit. Finally, electron backscatter diffraction (EBSD) techniques were employed to investigate post-shock microstructural changes.

Ultra high-speed x-ray imaging of laser-driven shock compression using synchrotron light

Science.gov (United States)

Olbinado, Margie P.; Cantelli, Valentina; Mathon, Olivier; Pascarelli, Sakura; Grenzer, Joerg; Pelka, Alexander; Roedel, Melanie; Prencipe, Irene; Laso Garcia, Alejandro; Helbig, Uwe; Kraus, Dominik; Schramm, Ulrich; Cowan, Tom; Scheel, Mario; Pradel, Pierre; De Resseguier, Thibaut; Rack, Alexander

2018-02-01

A high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a time-resolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a polyurethane foam and a graphite rod by means of single-pulse synchrotron x-ray phase-contrast imaging with MHz frame rate. A 6 J, 10 ns pulsed laser was used to generate shock compression. Physical processes governing the laser-induced dynamic response such as elastic compression, compaction, pore collapse, fracture, and fragmentation have been imaged; and the advantage of exploiting the partial spatial coherence of a synchrotron source for studying low-density, carbon-based materials is emphasized. The successful combination of a high-energy laser and ultra high-speed x-ray imaging using synchrotron light demonstrates the potentiality of accessing complementary information from scientific studies of laser-driven shock compression.

Thermal Shielding Effects of a Damaged Shock Absorber and an Intact Shock Absorber

Energy Technology Data Exchange (ETDEWEB)

Bang, K. S.; Lee, J. C.; Kim, K. Y.; Seo, C. S.; Seo, K. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-05-15

In order to safely transport the radioactive waste arising from the hot test of an ACP(Advanced Spent Fuel Conditioning Process) a shipping package is required. Therefore, KAERI is developing a shipping package to transport the radioactive waste arising from the ACPF during a hot test. The regulatory requirements for a Type B package are specified in the Korea Most Act 2009-37, IAEA Safety Standard Series No. TS-R-1, and US 10 CFR Part. These regulatory guidelines classify the hot cell cask as a Type B package, and state that the Type B package for transporting radioactive materials should be able to withstand a test sequence consisting of a 9 m drop onto an unyielding surface, a 1 m drop onto a puncture bar, and a 30 minute fully engulfing fire. Greiner et al. investigated the thermal protection provided by shock absorbers by using the CAFE computer code. To evaluate the thermal shielding effect of the shock absorber, the thermal test was performed by using a 1/2 scale model with a shock absorber which was damaged by both a 9 m drop test and a 1 m puncture test. For the purpose of comparison, the thermal test was also carried out by using a 1/2 scale model with the intact shock absorber

Analysis of compaction shock interactions during DDT of low density HMX

Science.gov (United States)

Rao, Pratap T.; Gonthier, Keith A.

2017-01-01

Deflagration-to-Detonation Transition (DDT) in confined, low density granular HMX occurs by a complex mechanism that involves compaction shock interactions within the material. Piston driven DDT experiments indicate that detonation is abruptly triggered by the interaction of a strong combustion-supported secondary shock and a piston-supported primary (input) shock, where the nature of the interaction depends on initial packing density and primary shock strength. These interactions influence transition by affecting dissipative heating within the microstructure during pore collapse. Inert meso-scale simulations of successive shock loading of low density HMX are performed to examine how dissipation and hot-spot formation are affected by the initial density, and the primary and secondary shock strengths. This information is used to formulate an ignition and burn model for low density HMX that accounts for the effect of shock densensitization on burn. Preliminary DDT predictions are presented that illustrate how primary shock strength affects the transition mechanism.

Shock Dynamics in Stellar Outbursts. I. Shock Formation

Energy Technology Data Exchange (ETDEWEB)

Ro, Stephen; Matzner, Christopher D., E-mail: ro@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

2017-05-20

Wave-driven outflows and non-disruptive explosions have been implicated in pre-supernova outbursts, supernova impostors, luminous blue variable eruptions, and some narrow-line and superluminous supernovae. To model these events, we investigate the dynamics of stars set in motion by strong acoustic pulses and wave trains, focusing on nonlinear wave propagation, shock formation, and an early phase of the development of a weak shock. We identify the shock formation radius, showing that a heuristic estimate based on crossing characteristics matches an exact expansion around the wave front and verifying both with numerical experiments. Our general analytical condition for shock formation applies to one-dimensional motions within any static environment, including both eruptions and implosions. We also consider the early phase of shock energy dissipation. We find that waves of super-Eddington acoustic luminosity always create shocks, rather than damping by radiative diffusion. Therefore, shock formation is integral to super-Eddington outbursts.

Advances in shock timing experiments on the National Ignition Facility

International Nuclear Information System (INIS)

Robey, H F; Celliers, P M; Moody, J D; Sater, J; Parham, T; Kozioziemski, B; Dylla- Spears, R; Ross, J S; LePape, S; Ralph, J E; Hohenberger, M; Dewald, E L; Berzak Hopkins, L; Kroll, J J; Yoxall, B E; Hamza, A V; Landen, O L; Edwards, M J; Boehly, T R; Nikroo, A

2016-01-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion (ICF) implosions were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. (paper)

Advances in shock timing experiments on the National Ignition Facility

Science.gov (United States)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

2016-03-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion (ICF) implosions were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique.

Nitrogen-rich heterocycles as reactivity retardants in shocked insensitive explosives.

Science.gov (United States)

Manaa, M Riad; Reed, Evan J; Fried, Laurence E; Goldman, Nir

2009-04-22

We report the first quantum-based multiscale simulations to study the reactivity of shocked perfect crystals of the insensitive energetic material triaminotrinitrobenzene (TATB). Tracking chemical transformations of TATB experiencing overdriven shock speeds of 9 km/s for up to 0.43 ns and 10 km/s for up to 0.2 ns reveal high concentrations of nitrogen-rich heterocyclic clusters. Further reactivity of TATB toward the final decomposition products of fluid N(2) and solid carbon is inhibited due to the formation of these heterocycles. Our results thus suggest a new mechanism for carbon-rich explosive materials that precedes the slow diffusion-limited process of forming the bulk solid from carbon clusters and provide fundamental insight at the atomistic level into the long reaction zone of shocked TATB.

Paving materials for heat island mitigation

Energy Technology Data Exchange (ETDEWEB)

Pomerantz, M.; Akbari, H.; Chen, A.; Taha, H. [Lawrence Berkeley National Lab., CA (United States); Rosenfeld, A.H. [Dept. of Energy, Washington, DC (United States)

1997-11-01

This report summarizes paving materials suitable for urban streets, driveways, parking lots and walkways. The authors evaluate materials for their abilities to reflect sunlight, which will reduce their temperatures. This in turn reduces the excess air temperature of cities (the heat island effect). The report presents the compositions of the materials, their suitability for particular applications, and their approximate costs (in 1996). Both new and resurfacing are described. They conclude that, although light-colored materials may be more expensive than conventional black materials, a thin layer of light-colored pavement may produce energy savings and smog reductions whose long-term worth is greater than the extra cost.

Experimental Shock Damage Risk Assessment for New Generation TAS-B Plasmic Propulsion Unit

Science.gov (United States)

Garnier, J.; De Fruytier, C.

2014-06-01

This paper presents the methodology and the results of the shock test campaign conducted by TAS-B to qualify the PPU Mk2 unit in regards of increased shock levels.This unit supplies and controls two Plasma Thrusters used for satellite orbit keeping and attitude control. The PPU Mk2 unit mechanical design is based on a modular architecture. The different modules are mounted on a baseplate insuring thermal spreading and improved equipment flatness. The unit dimensions are 390 x 190 x 190 mm3 for a total mass of 11.5 kg.The PPU Mk2 contains several components sensitive to shock like specific inductors, transformers and relays. Due to an increasing of the shock specification in regards of the previous generation of PPU, it has been proposed to assess the good withstanding of these components and in order to mitigate the risks on the Qualification Model, a preliminary shock test has been performed on a Structural Model. This model is fully representative of the flight equipment in terms of mechanical interfaces and has been designed to have the same mechanical behaviour (same mass and main modes). Critical components have been embedded in this structural model in order to test their shock withstanding. Preliminary to this Structural Model, qualification at sensitive components levels has been performed through vibrations, shocks (half-sine) and thermal cycling. Evolution of the electrical main parameters has been followed to detect any degradation of the performance during this test campaigns.Then, the structural model has been instrumented to acquire the global behaviour of the equipment. Success criteria have been defined concerning mechanical behaviour before and after shocks, admissible electrical variations, visual inspections.After calibration phasis of the test bench, the shock test of the PPU Mk2 SM has been successfully conducted. The good test results allowed applying these shock levels confidently on the PPU Mk2 EQM model.

Apparatus for reducing shock and overpressure

Science.gov (United States)

Walter, C.E.

1975-01-28

An apparatus for reducing shock and overpressure is particularly useful in connection with the sequential detonation of a series of nuclear explosives under ground. A coupling and decoupling arrangement between adjacent nuclear explosives in the tubing string utilized to emplace the explosives is able to support lower elements on the string but yields in a manner which absorbs energy when subjected to the shock wave produced upon detonation of one of the explosives. Overpressure is accomodated by an arrangement in the string which provides an additional space into which the pressurized material can expand at a predetermined overpressure. (10 claims)

Temperature measurement of tin under shock compression

International Nuclear Information System (INIS)

Hereil, Pierre-Louis; Mabire, Catherine

2002-01-01

The results of pyrometric measurements performed at the interface of a tin target with a LiF window material are presented for stresses ranging from 38 to 55 GPa. The purpose of the study is to analyze the part of the interface in the temperature measurement by a multi-channel pyrometric device. The results show that the glue used at target/window interface remains transparent under shock. The values of temperature measured at the tin/LiF interface are consistent with the behavior of tin under shock

Some numerical approaches of creep, thermal shock, damage

Indian Academy of Sciences (India)

Creep can be satisfactorily described by a kinematic hardening, and exhibits different creep rates in tension and compression. Concerning the thermal shock of materials, the numerical approach depends whether or not the material is able to develop a sprayed out damage, leading to micro- or macro-cracking. Finally ...

High pressure multiple shock response of aluminum

International Nuclear Information System (INIS)

Lawrence, R.J.; Asay, J.R.

1977-01-01

It is well known that both dynamic yield strength and rate-dependent material response exert direct influence on the development of surface and interface instabilities under conditions of strong shock loading. A detailed understanding of these phenomena is therefore an important aspect of the analysis of dynamic inertial confinement techniques which are being used in such applications as the generation of controlled thermonuclear fusion. In these types of applications the surfaces and interfaces under consideration can be subjected to cyclic loading characterized by shock pressures on the order of 100 GPa or more. It thus becomes important to understand how rate effects and material strength differ from the values observed in the low pressure regime where they are usually measured, as well as how they are altered by the loading history

Thermal shock behaviour of different tungsten grades under varying conditions

Energy Technology Data Exchange (ETDEWEB)

Wirtz, Oliver Marius

2012-07-19

Thermonuclear fusion power plants are a promising option to ensure the energy supply for future generations, but in many fields of research enormous challenges have to be faced. A major step on the way to the prototype fusion reactor DEMO will be ITER which is build in Cadarache, southern France. One of the most critical issues is the field of in-vessel materials and components, in particular the plasma facing materials (PFM). PFMs that will be used in a device like ITER have to withstand severe environmental conditions in terms of steady state and transient thermal loads as well as high particle fluxes such as hydrogen, helium and neutrons. Candidate wall materials are beryllium, tungsten and carbon based materials like CFC (carbon fibre composite). Tungsten is the most promising material for an application in the divertor region with very severe loading conditions and it will most probably also be used as PFM for DEMO. Hence, this work focuses on the investigation of the thermal shock response of different tungsten grades in order to understand the damage mechanisms and to identify material parameters which influence this behaviour under ITER and DEMO relevant operation conditions. Therefore the microstructure and the mechanical and thermal properties of five industrially manufactured tungsten grades were characterised. All five tungsten grades were exposed to transient thermal events with very high power densities of up to 1.27 GWm{sup -2} at varying base temperatures between RT and 600 C in the electron beam device JUDITH 1. The pulse numbers were limited to a maximum of 1000 in order to avoid immoderate workload on the test facility and to have enough time to cover a wide range of loading conditions. The results of this damage mapping enable to define different damage and cracking thresholds for the investigated tungsten grades and to identify certain material parameters which influence the location of these thresholds and the distinction of the induced

Thermal shock behaviour of different tungsten grades under varying conditions

International Nuclear Information System (INIS)

Wirtz, Oliver Marius

2012-01-01

Thermonuclear fusion power plants are a promising option to ensure the energy supply for future generations, but in many fields of research enormous challenges have to be faced. A major step on the way to the prototype fusion reactor DEMO will be ITER which is build in Cadarache, southern France. One of the most critical issues is the field of in-vessel materials and components, in particular the plasma facing materials (PFM). PFMs that will be used in a device like ITER have to withstand severe environmental conditions in terms of steady state and transient thermal loads as well as high particle fluxes such as hydrogen, helium and neutrons. Candidate wall materials are beryllium, tungsten and carbon based materials like CFC (carbon fibre composite). Tungsten is the most promising material for an application in the divertor region with very severe loading conditions and it will most probably also be used as PFM for DEMO. Hence, this work focuses on the investigation of the thermal shock response of different tungsten grades in order to understand the damage mechanisms and to identify material parameters which influence this behaviour under ITER and DEMO relevant operation conditions. Therefore the microstructure and the mechanical and thermal properties of five industrially manufactured tungsten grades were characterised. All five tungsten grades were exposed to transient thermal events with very high power densities of up to 1.27 GWm -2 at varying base temperatures between RT and 600 C in the electron beam device JUDITH 1. The pulse numbers were limited to a maximum of 1000 in order to avoid immoderate workload on the test facility and to have enough time to cover a wide range of loading conditions. The results of this damage mapping enable to define different damage and cracking thresholds for the investigated tungsten grades and to identify certain material parameters which influence the location of these thresholds and the distinction of the induced damages

Slow shocks and their transition to fast shocks in the inner solar wind

International Nuclear Information System (INIS)

Wang, Y.C.

1987-01-01

The jump conditions of MHD shocks may be directly calculated as functions of three upstream conditions: the shock Alfven number based on the normal component of the relative shock speed, the shock angle, and the plasma β value. The shock Alfven number is less than 1 for a slow shock and greater than 1 for a fast shock. A traveling, forward shock can be a slow shock in coronal space, where the Alfven speed is of the order of 1000 km/s. The surface of a forward slow shock has a bow-shaped geometry with its nose facing toward the sun. The decrease in the Alfven speed at increasing heliocentric distance causes the shock Alfven number of a forward slow shock to become greater than 1, and the shock eventually evolves from a slow shock into a fast shock. During the transition the shock system consists of a slow shock, a fast shock, and a rotational discontinuity. They intersect along a closed transition line. As the system moves outward from the sun, the area enclosed by the transition line expands, the fast shock grows stronger, and the slow shock becomes weaker. Eventually, the slow shock diminishes, and the entire shock system evolves into a forward fast shock. copyrightAmerican Geophysical Union 1987

Temperature measurements of shocked translucent materials by time-resolved infrared radiometry

International Nuclear Information System (INIS)

Von Holle, W.G.

1981-01-01

Infrared emission in the range 2 to 5.5 μm has been used to measure temperatures in shock-compressed states of nitromethane, cyclohexane and benzene and in polycrystalline KBr. Polymethylmethacrylate shows anomolous emission probably associated with some heterogeneity

Characterization of shocked beryllium

Directory of Open Access Journals (Sweden)

Papin P.A.

2012-08-01

Full Text Available While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. In the current work, high strain rate tests were conducted using both explosive drive and a gas gun to accelerate the material. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. Two constitutive strength (plasticity models, the Preston-Tonks-Wallace (PTW and Mechanical Threshold Stress (MTS models, were calibrated using common quasi-static and Hopkinson bar data. However, simulations with the two models give noticeably different results when compared with the measured experimental wave profiles. The experimental results indicate that, even if fractured by the initial shock loading, the Be remains sufficiently intact to support a shear stress following partial release and subsequent shock re-loading. Additional “arrested” drive shots were designed and tested to minimize the reflected tensile pulse in the sample. These tests were done to both validate the model and to put large shock induced compressive loads into the beryllium sample.

Severe accident mitigation through containment design

International Nuclear Information System (INIS)

Bergeron, K.D.

1990-01-01

Recent U.S. Department of Energy plans to construct a Heavy Water Reactor for the production of defense nuclear materials have created a unique opportunity to explore ways to mitigate severe accident concerns in the design stage. Drawing on an extensive background in US-NRC-sponsored severe accident work, Sandia National Laboratories has been exploring a number of Heavy Water New Production Reactor (HW-NPR) containment design strategies that might mitigate the consequences of a core-melt accident without greatly impacting construction cost or reactor operations. Severe accident specialists have undertaken these assessments with the intent of providing the plant designers with some of the phenomenological advantages and disadvantages of various mitigation strategies. This paper will highlight some of the more interesting concepts and summarize the results obtained. (author). 9 refs., 2 tabs

Severe accident mitigation through containment design

International Nuclear Information System (INIS)

Bergeron, K.D.

1990-01-01

Recent US Department of Energy plans to construct a Heavy Water Reactor for the production of defense nuclear materials have created a unique opportunity to explore ways to mitigate severe accident concerns in the design stage. Drawing on an extensive background in USNRC-sponsored severe accident work, Sandia National Laboratories has been exploring a number of Heavy Water New Production Reactor (HW-NPR) containment design strategies that might mitigate the consequences of a core-melt accident without greatly impacting construction cost or reactor operations. Severe accident specialists have undertaken these assessments with the intent of providing the plant designers with some of the phenomenological advantages and disadvantages of various mitigation strategies. This paper will highlight some of the more interesting concepts and summarize the results obtained. 9 refs., 2 tabs

Some recent advances of shock wave physics research at the Laboratory for Shock Wave and Detonation Physics Research

CERN Document Server

Jing Fu Qian

2002-01-01

Progress made in recent years on three topics that have been investigated at the Laboratory for Shock Wave and Detonation Physics Research are presented in this report. (1) A new equation of state (EOS) has been derived which can be used from a standard state to predict state variable change along an isobaric path. Good agreements between calculations for some representative metals using this new EOS and experiments have been found, covering a wide range from hundreds of MPa to hundreds of GPa and from ambient temperature to tens of thousands of GPa. (2) An empirical relation of Y/G = constant (Y is yield strength, G is shear modulus) at HT-HP has been reinvestigated and confirmed by shock wave experiment. 93W alloy was chosen as a model material. The advantage of this relation is that it is beneficial to formulate a kind of simplified constitutive equation for metallic solids under shock loading, and thus to faithfully describe the behaviours of shocked solids through hydrodynamic simulations. (3) An attempt...

Investigation of Shock-Induced Reactions in a Ni+Al Powder Mixture

International Nuclear Information System (INIS)

Eakins, D. E.; Thadhani, N. N.

2006-01-01

The shock-compression and reaction response of equi-volumetric micron-scale (∼50-60% dense) spherical nickel and aluminum powder mixtures is investigated in the range of the calculated crush-up pressure (P = 0.4 GPa) and up to 6 GPa. Time resolved stress measurements (using PVDF gauges) coupled with VISAR data is used to determine the shock states. Evidence of reaction or lack thereof is inferred by comparing the measured states with calculated Hugoniot state of reaction products based on the ballotechnic model proposed by Bennett and Horie, (Shock Waves 4:127-136). Post-impact micro-structural analysis of recovered material and comparison of calculated and measured product states is used to establish the criterion for reaction occurring in the shock or post-shock states

Relative Shock Effects in Mixed Powders of Calcite, Gypsum, and Quartz: A Calibration Scheme from Shock Experiments

Science.gov (United States)

Bell, Mary S.

2009-01-01

The shock behavior of calcite and gypsum is important in understanding the Cretaceous/Tertiary event and other terrestrial impacts that contain evaporite sediments in their targets. Most interest focuses on issues of devolatilization to quantify the production of CO2 or SO2 to better understand their role in generating a temporary atmosphere and its effects on climate and biota [e.g., papers in 1,2,3,4]. Devolatilization of carbonate is also important because the dispersion and fragmentation of ejecta is strongly controlled by the expansion of large volumes of gas during the impact process as well [5,6]. Shock recovery experiments for calcite yield seemingly conflicting results: early experimental devolatilization studies [7,8,9] suggested that calcite was substantially outgassed at 30 GPa (> 50%). However, the recent petrographic work of [10,11,12] presented evidence that essentially intact calcite is recovered from 60 GPa experiments. [13] reported results of shock experiments on anhydrite, gypsum, and mixtures of those phases with silica. Their observations indicate little or no devolatilization of anhydrite shocked to 42 GPa and that the fraction of sulfur, by mass, that degassed is approx.10(exp -2) of theoretical prediction. In another (preliminary) report of shock experiments on calcite, anhydrite, and gypsum, [14] observe calcite recrystallization when shock loaded at 61 GPa, only intensive plastic deformation in anhydrite shock loaded at 63 GPa, and gypsum converted to anhydrite when shock loaded at 56 GPa. [15] shock loaded anhydrite and quartz to a peak pressure of 60 GPa. All of the quartz grains were trans-formed to glass and the platy anhydrite grains were completely pseudomorphed by small crystallized anhydrite grains. However, no evidence of interaction between the two phases could be observed and they suggest that recrystallization of anhydrite grains is the result of a solid state transformation. [16] reanalyzed the calcite and anhydrite shock

Microjetting from a grooved Al surface under supported and unsupported shocks

Science.gov (United States)

Shao, Jian-Li; Wang, Pei; He, An-Min

2014-08-01

Using molecular dynamics methods, we simulate and compare the microjetting from a grooved Al surface induced by supported and unsupported shocks at different breakout pressures. Via the analysis on the microjetting morphologies and mass distributions, we find that the threshold of shock breakout pressure for the microjetting formation is almost same, but the variation of microjet mass with shock pressure shows a great difference for the two loading patterns. Under supported shock loading, the microjet mass keeps a continuous increase with increasing shock pressure, and release melting can enhance it markedly. By contrast, the microjet mass under unsupported shocks is smaller and seems no remarkable increase with shock pressure in our simulations (at extremely short pulses), implying the shock decaying can weaken the microjetting. Of course, a large area of fragments near the surface may form in this case. The microjet source distributions corresponding to supported and unsupported shocks are presented. It is found that the former becomes apparently broader than the latter with increasing shock pressure. Besides, the microjet tip velocity under supported shocks may appear a reduction because of the material strength effect below release melting. While under unsupported shocks, all the microjets in solid and melted states will experience the reduction of tip velocity. These decrements of tip velocity can be fitted by an exponential function.

Toxic shock syndrome

Science.gov (United States)

Staphylococcal toxic shock syndrome; Toxic shock-like syndrome; TSLS ... Toxic shock syndrome is caused by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock- ...

Shear Stress in Nickel and Ni-60Co under One-Dimensional Shock Loading

International Nuclear Information System (INIS)

Workman, A.; Wallwork, A.; Meziere, Y. J. E.; Millett, J. C. F.; Bourne, N. K.

2006-01-01

The dynamic response of pure nickel (Ni), and its alloy, Ni-60Co (by weight %), has been investigated during one-dimensional shock loading. Few materials' properties are different and the only significantly altered feature is the reduced stacking fault energy (SFE) for the Ni-60Co. This paper considers the effect of this reduced SFE on the shear strength. Data (in terms of shock stress, particle velocity and shock velocity) are also presented. The influence on the shear stress, τ of cobalt additions in nickel are then investigated and presented. Results indicate that the lateral stress is increasing in both materials with the increasing impact stress. The shear stress was found to be higher in the nickel than in the Ni-60Co. The progressive decrease of the lateral stress noted during loading indicates a complex mechanism of deformation behind the shock front

Comparison of the thermal shock performance of different tungsten grades and the influence of microstructure on the damage behaviour

International Nuclear Information System (INIS)

Wirtz, M; Linke, J; Pintsuk, G; Singheiser, L; Uytdenhouwen, I

2011-01-01

The thermal shock performances of two new tungsten grades with 1 and 5 wt% of tantalum were characterized with the electron beam facility JUDITH 1. As a reference material, ultra-high-purity tungsten (W-UHP) with a purity of 99.9999 wt% was used. The induced thermal shock crack networks and surface modifications were analysed by a scanning electron microscope, light microscopy and laser profilometry. Damage and cracking thresholds were defined for all materials as a function of absorbed power density and base temperature. The materials showed significantly different thermal shock behaviour, which is, among others, expressed by differences in cracking patterns, i.e. crack distance and depth. These results allow us to quantify the influence of the materials' mechanical and thermal properties on the thermal shock performance. Furthermore, the specific grain structure of the materials has a significant influence on crack propagation towards the bulk material.

Proximal forearm extensor muscle strain is reduced when driving nails using a shock-controlled hammer.

Science.gov (United States)

Buchanan, Kimberly A; Maza, Maria; Pérez-Vázquez, Carlos E; Yen, Thomas Y; Kijowski, Richard; Liu, Fang; Radwin, Robert G

2016-10-01

Repetitive hammer use has been associated with strain and musculoskeletal injuries. This study investigated if using a shock-control hammer reduces forearm muscle strain by observing adverse physiological responses (i.e. inflammation and localized edema) after use. Three matched framing hammers were studied, including a wood-handle, steel-handle, and shock-control hammer. Fifty volunteers were randomly assigned to use one of these hammers at a fatiguing pace of one strike every second, to seat 20 nails in a wood beam. Magnetic resonance imaging was used to scan the forearm muscles for inflammation before the task, immediately after hammering, and one to two days after. Electromyogram signals were measured to estimate grip exertions and localized muscle fatigue. High-speed video was used to calculate the energy of nail strikes. While estimated grip force was similar across the three hammers, the shock-control hammer had 40% greater kinetic energy upon impact and markedly less proximal extensor muscle edema than the wood-handle and steel-handle hammers, immediately after use (phandle shock can mitigate strain in proximal forearm extensor muscles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Study on the properties of porous magnetorheological elastomers under shock effect

International Nuclear Information System (INIS)

Ju, B X; Yu, M; Fu, J; Zheng, X; Yang, Q

2013-01-01

As a safe protector, buffer has been widely applied to engineering applications. The properties of cushion materials play a key role in the performance of the buffer under shock loading. Magnetorheological elastomers (MRE) are a kind of novel smart materials and show to have a controllable, field-dependent modulus, which have attracted increasing attentions and broad application prospects. This paper aims to fabricate a new kind of MRE, named as porous MRE, and study on the properties of porous MRE under shock effect in the presence of an external magnetic field. Three kinds of MRE samples based on polyurethane matrix were prepared without external magnetic field, and ammonium bicarbonate was used as foaming agent with content of 0 wt.%, 0.26 wt.%, 0.67 wt.%, respectively. The microstructures of the sample were observed by using a digital microscope, and image processing and analysis was applied to calculate the parameters of porous MRE. A sleeve structure and mass block were used to test the shock performance of porous MRE under shear mode, and an electromagnetic vibration and shock table was used to provide shock signal with half-sine shock signal. The results show that the content of foaming agent has an obvious influence on the microstructures of porous MRE. The porosity of the porous MRE samples increases with increasing of foaming agent content. Moreover, experimental results show that shock energy dissipation capacity is better than that of traditional MRE. This study is expected to provide guidance in the application of MRE in practical devices, such as in buffer devices.

Effects of Phase Transformations and Dynamic Material Strength on Hydrodynamic Instability Evolution in Metals

Science.gov (United States)

Opie, Saul

Hydrodynamic phenomena such as the Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities can be described by exponential/linear growth of surface perturbations at a bimaterial interface when subjected to constant/impulsive acceleration. A challenge in designing systems to mitigate or exploit these effects is the lack of accurate material models at large dynamic strain rates and pressures. In particular, little stress-strain constitutive information at large strain rates and pressures is available for transient material phases formed at high pressures, and the continuum effect the phase transformation process has on the instability evolution. In this work, a phase-aware isotropic strength model is developed and partially validated with a novel RM-based instability experiment in addition to existing data from the literature. With the validated material model additional simulations are performed to provide insight into to the role that robust material constitutive behavior (e.g., pressure, temperature, rate dependence) has on RM instability and how RM instability experiments can be used to characterize and validated expected material behavior. For phase aware materials, particularly iron in this work, the simulations predict a strong dependence on the Atwood number that single phase materials do not have. At Atwood numbers close to unity, and pressures in the high pressure stability region, the high pressure phase dominates the RM evolution. However, at Atwood numbers close to negative one, the RM evolution is only weakly affected by the high-pressure phase even for shocks well above the phase transformation threshold. In addition to RM evolution this work looks at the closely related shock front perturbation evolution. Existing analytical models for isentropic processes in gases and liquids are modified for metal equation of states and plastic behavior for the first time. It is found that the presence of a volume collapsing phase transformation with increased

Shock response of Ni/Al reactive inter-metallic composites

Science.gov (United States)

Cherukara, Mathew; Germann, Timothy; Kober, Edward; Strachan, Alejandro

2014-03-01

Intermolecular reactive composites find diverse applications in defense, microelectronics and medicine, where strong, localized sources of heat are required. Motivated by experimental work which has shown that high-energy ball milling can significantly improve the reactivity as well as the ease of ignition of Ni/Al inter-metallic composites, we present large scale (~41 million atom) molecular dynamics simulations of shock-induced chemistry in porous, polycrystalline, lamellar Ni/Al nano-composites, which are designed to capture the microstructure that is obtained post milling. Shock propagation in these porous, lamellar materials is observed to be extremely diffuse, leading to substantial inhomogeneity in the local stress states of the material. We describe the importance of pores as sites of initiation, where local temperatures can rise to several thousands of degrees, and chemical mixing is accelerated by vortex formation and jetting in the pore. We also follow the evolution of the chemistry after the shock passage by allowing the sample to ``cook'' under the shock induced pressures and temperatures for up to 0.5 ns. Multiple ``tendril-like'' reaction fronts, born in the cauldron of the pores, propagate rapidly through the sample, consuming it within a nanosecond. US Defense Threat Reduction Agency, Contract No. HDTRA1-10-1-0119.

Coronal mass ejection shock fronts containing the two types of intermediate shocks

International Nuclear Information System (INIS)

Steinolfson, R.S.; Hundhausen, A.J.

1990-01-01

Numerical solutions of the time-dependent, magnetohydrodynamic (MHD) equations in two dimensions are used to demonstrate the formation of both types of intermediate shocks in a single shock front for physical conditions that are an idealization of those expected to occur in some observed coronal mass ejections. The key to producing such a shock configuration in the simulations is the use of an initial atmosphere containing a magnetic field representative of that in a coronal streamer with open field lines overlying a region of closed field lines. Previous attempts using just open field lines (perpendicular to the surface) produced shock configurations containing just one of the two intermediate shock types. A schematic of such a shock front containing both intermediate shock types has been constructed previously based solely on the known properties of MHD shocks from the Rankine-Hugoniot equations and specific requirements placed on the shock solution at points along the front where the shock normal and upstream magnetic field are aligned. The shock front also contains, at various locations along the front, a hydrodynamic (nonmagnetic) shock, a switch-on shock, and a fast shock in addition to the intermediate shocks. This particular configuration occurs when the shock front speed exceeds the upstream (preshock) intermediate wave speed but is less than a critical speed defined in the paper (equation 1) along at least some portion of the shock front. A distinctive feature of the front is that it is concave upward (away from the surface) near the region where the field in the preshock plasma is normal to the front of near the central portion of the shock front

Structure of shocks in solids and liquids: Six reprints with an introduction

International Nuclear Information System (INIS)

Wallace, D.C.

1991-01-01

This monograph consists of six papers on the theory of shocks in solids and liquids, reprinted from Physical Review, together with an introduction summarizing the complete shock theory and its limitations. The shock theory of this monograph is based on the principles of irreversible thermodynamics, characterized as follows. First, in equilibrium thermodynamics, materials are required to pass through states which lie on the equilibrium surface. In irreversible thermodynamics, materials pass through nonequilibrium states, but only those states which are close to the equilibrium surface, specifically, those states for which the equilibrium properties of temperature and entropy are still reasonably well defined. To construct an irreversible thermodynamic theory it is necessary to define the variables which measure the departure from equilibrium, to express the effect of these variables by a modification of the equilibrium thermodynamic equations, and to write an equation for the (irreversible) entropy generation. These principles are applied to planar shocks in the reprints collected here

A numerical study of Richtmyer endash Meshkov instability driven by cylindrical shocks

International Nuclear Information System (INIS)

Zhang, Q.; Graham, M.J.

1998-01-01

As an incident shock wave hits a material interface between two fluids of different densities, the interface becomes unstable. Small disturbances at the interface start to grow. This interfacial instability is known as a Richtmyer endash Meshkov (RM) instability. It plays an important role in the studies of inertial confinement fusion and supernova. The majority of studies of the RM instability were in plane geometry emdash namely, plane shocks in Cartesian coordinates. We present a systematic numerical study of the RM instability driven by cylindrical shocks for both the imploding and exploding cases. The imploding (exploding) case refers to a cylindrical shock colliding with the material interface from the outside in (inside out). The phenomenon of reshock caused by the waves reflected from the origin is also studied. A qualitative understanding of this system has been achieved. Detailed studies of the growth rate of the fingers at the unstable interface are presented. copyright 1998 American Institute of Physics

Scaling Laws for Unstable Interfaces Driven by Strong Shocks in Cylindrical Geometry

International Nuclear Information System (INIS)

Zhang, Q.; Graham, M.J.; Graham, M.J.

1997-01-01

The Richtmyer-Meshkov (RM) instability is an interfacial interface between two fluids of different densities driven by shock waves and plays an important role in the studies of inertial confinement fusion and of supernovas. So far, most of the studies are for RM unstable interfaces driven by weak or intermediate shocks in planar geometry. For experiments conducted at the Nova laser, the unstable material interface is accelerated by very strong shocks. In this Letter, we present scaling laws for the RM unstable interface driven by strong imploding and exploding shocks. copyright 1997 The American Physical Society

Enteral tranexamic acid attenuates vasopressor resistance and changes in α1-adrenergic receptor expression in hemorrhagic shock.

Science.gov (United States)

Santamaria, Marco Henry; Aletti, Federico; Li, Joyce B; Tan, Aaron; Chang, Monica; Leon, Jessica; Schmid-Schönbein, Geert W; Kistler, Erik B

2017-08-01

Irreversible hemorrhagic shock is characterized by hyporesponsiveness to vasopressor and fluid therapy. Little is known, however, about the mechanisms that contribute to this phenomenon. Previous studies have shown that decreased intestinal perfusion in hemorrhagic shock leads to proteolytically mediated increases in gut permeability, with subsequent egress of vasoactive substances systemically. Maintenance of blood pressure is achieved in part by α1 receptor modulation, which may be affected by vasoactive factors; we thus hypothesized that decreases in hemodynamic stability and vasopressor response in shock can be prevented by enteral protease inhibition. Rats were exposed to experimental hemorrhagic shock (35 mm Hg mean arterial blood pressure for 2 hours, followed by reperfusion for 2 hours) and challenged with phenylephrine (2 μg/kg) at discrete intervals to measure vasopressor responsiveness. A second group of animals received enteral injections with the protease inhibitor tranexamic acid (TXA) (127 mM) along the small intestine and cecum 1 hour after induction of hemorrhagic shock. Blood pressure response (duration and amplitude) to phenylephrine after reperfusion was significantly attenuated in animals subjected to hemorrhagic shock compared with baseline and control nonshocked animals and was restored to near baseline by enteral TXA. Arteries from shocked animals also displayed decreased α1 receptor density with restoration to baseline after enteral TXA treatment. In vitro, rat shock plasma decreased α1 receptor density in smooth muscle cells, which was also abrogated by enteral TXA treatment. Results from this study demonstrate that experimental hemorrhagic shock leads to decreased response to the α1-selective agonist phenylephrine and decreased α1 receptor density via circulating shock factors. These changes are mitigated by enteral TXA with correspondingly improved hemodynamics. Proteolytic inhibition in the lumen of the small intestine improves

A structural investigation of third-currency shocks to bilateral exchange rates

OpenAIRE

Melecky, Martin

2007-01-01

An exchange rate between two currencies can be materially affected by shocks emerging from a third country. A US demand shock, for example, can affect the exchange rate between the euro and the yen. Since positive US demand shocks have a greater positive impact on Japanese interest rates than on eurozone rates, the yen appreciates against the euro in response. Using quarterly data on the U.S., the euro area and Japan from 1981 to 2006, this paper shows that the third-currency effects are sign...

Shock fabrics in fine-grained micrometeorites

Science.gov (United States)

Suttle, M. D.; Genge, M. J.; Russell, S. S.

2017-10-01

The orientations of dehydration cracks and fracture networks in fine-grained, unmelted micrometeorites were analyzed using rose diagrams and entropy calculations. As cracks exploit pre-existing anisotropies, analysis of their orientation provides a mechanism with which to study the subtle petrofabrics preserved within fine-grained and amorphous materials. Both uniaxial and biaxial fabrics are discovered, often with a relatively wide spread in orientations (40°-60°). Brittle deformation cataclasis and rotated olivine grains are reported from a single micrometeorite. This paper provides the first evidence for impact-induced shock deformation in fine-grained micrometeorites. The presence of pervasive, low-grade shock features in CM chondrites and CM-like dust, anomalously low-density measurements for C-type asteroids, and impact experiments which suggest CM chondrites are highly prone to disruption all imply that CM parent bodies are unlikely to have remained intact and instead exist as a collection of loosely aggregated rubble-pile asteroids, composed of primitive shocked clasts.

High-energy air shock study in steel and grout pipes

International Nuclear Information System (INIS)

Glenn, H.D.; Kratz, H.R.; Keough, D.D.; Duganne, D.A.; Ruffner, D.J.; Swift, R.P.; Baum, D.

1979-01-01

Voitenko compressors are used to generate 43 mm/μs air shocks in both a steel and a grout outlet pipe containing ambient atmospheric air. Fiber-optic ports provide diaphragm burst times, time-of-arrival (TOA) data, and velocities for the shock front along the 20-mm-ID exit pipes. Pressure profiles are obtained at higher enthalpy shock propagation than ever before and at many locations along the exit pipes. Numerous other electronic sensors and postshot observations are described, as well as experimental results. The primary objectives of the experiments are as follows: (1) provide a data base for normalization/improvement of existing finite-difference codes that describe high-energy air shocks and gas propagation; (2) obtain quantitative results on the relative attenuation effects of two very different wall materials for high-energy air shocks and gas flows. The extensive experimental results satisfy both objectives

Optical Spectroscopy Measurements of Shock Waves Driven by Intense Z-Pinch Radiation

International Nuclear Information System (INIS)

Asay, J.; Bernard, M.; Bailey, J.E.; Carlson, A.L.; Chandler, G.A.; Hall, C.A.; Hanson, D.; Johnston, R.; Lake, P.; Lawrence, J.

1999-01-01

Z-pinches created using the Z accelerator generate approximately220 TW, 1.7 MJ radiation pulses that heat large (approximately10 cm 3 ) hohlraums to 100-150 eV temperatures for times of order 10 nsec. We are performing experiments exploiting this intense radiation to drive shock waves for equation of state studies. The shock pressures are typically 1-10 Mbar with 10 nsec duration in 6-mm-diameter samples. In this paper we demonstrate the ability to perform optical spectroscopy measurements on shocked samples located in close proximity to the z-pinch. These experiments are particularly well suited to optical spectroscopy measurements because of the relatively large sample size and long duration. The optical emission is collected using fiber optics and recorded with a streaked spectrograph. Other diagnostics include VISAR and active shock breakout measurements of the shocked sample and a suite of diagnostics that characterize the radiation drive. Our near term goal is to use the spectral emission to obtain the temperature of the shocked material. Longer term objectives include the examination of deviations of the spectrum from blackbody, line emission from lower density regions, determination of kinetic processes in molecular systems, evaluation of phase transitions such as the onset of metalization in transparent materials, and characterization of the plasma formed when the shock exits the rear surface. An initial set of data illustrating both the potential and the challenge of these measurements is described

Empirical Model Development for Predicting Shock Response on Composite Materials Subjected to Pyroshock Loading. Volume 2, Part 1; Appendices

Science.gov (United States)

Gentz, Steven J.; Ordway, David O.; Parsons, David S.; Garrison, Craig M.; Rodgers, C. Steven; Collins, Brian W.

2015-01-01

The NASA Engineering and Safety Center (NESC) received a request to develop an analysis model based on both frequency response and wave propagation analyses for predicting shock response spectrum (SRS) on composite materials subjected to pyroshock loading. The model would account for near-field environment (approximately 9 inches from the source) dominated by direct wave propagation, mid-field environment (approximately 2 feet from the source) characterized by wave propagation and structural resonances, and far-field environment dominated by lower frequency bending waves in the structure. This document contains appendices to the Volume I report.

Shock timing measurements in DT ice layers

Science.gov (United States)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R. J.; Ross, J. S.; Lepape, S.; Ralph, J. E.; Berzak Hopkins, L. F.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

2013-10-01

Shock timing experiments on the National Ignition Facility (NIF) are routinely conducted using the keyhole target geometry, in which the strength and timing of multiple shocks are measured in a liquid-deuterium (D2) filled capsule interior. These targets have recently been modified to improve the surrogacy to ignition implosions by replacing the standard, continuous liquid D2 capsule fill with a deuterium-tritium (DT) ice layer with a central DT gas fill. These experiments remove any possible material surrogacy difference between D2 and DT as well as incorporating the physics of multiple shock release and recompression events from an ice layer of finite thickness, an effect that is absent in the liquid-filled targets. Experimental results and comparisons with numerical simulation are presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

Shock resistance testing

International Nuclear Information System (INIS)

Pouard, M.

1984-03-01

In the framework of mechanical tests and to answer the different requests for tests, the T.C.R (Transport Conditionnement et Retraitement) laboratory got test facilities. These installations allow to carry out tests of resistance to shocks, mainly at the safety level of components of nuclear power plants, mockups of transport casks for fuel elements and transport containers for radioactive materials. They include a tower and a catapult. This paper give a decription of the facilities and explain their operation way [fr

demystifying the shock of shocking

African Journals Online (AJOL)

(with a pulse), atrial fibrillation and atrial flutter. The energy dose in cardioversion is less (0.5. - 2 J/kg) than in defibrillation (2 - 4 J/kg). In cardioversion the shock is discharged synchronously with the native R wave of the patient. Without synchronisation,. VF can be induced if a shock is delivered during the refractory period ...

Emerging Radiation Health-Risk Mitigation Technologies

International Nuclear Information System (INIS)

Wilson, J.W.; Cucinotta, F.A.; Schimmerling, W.

2004-01-01

Past space missions beyond the confines of the Earth's protective magnetic field have been of short duration and protection from the effects of solar particle events was of primary concern. The extension of operational infrastructure beyond low-Earth orbit to enable routine access to more interesting regions of space will require protection from the hazards of the accumulated exposures of Galactic Cosmic Rays (GCR). There are significant challenges in providing protection from the long-duration exposure to GCR: the human risks to the exposures are highly uncertain and safety requirements places unreasonable demands in supplying sufficient shielding materials in the design. A vigorous approach to future radiation health-risk mitigation requires a triage of techniques (using biological and technical factors) and reduction of the uncertainty in radiation risk models. The present paper discusses the triage of factors for risk mitigation with associated materials issues and engineering design methods

Shock absorbing structure

International Nuclear Information System (INIS)

Kojima, Naoki; Matsushita, Kazuo.

1992-01-01

Small pieces of shock absorbers are filled in a space of a shock absorbing vessel which is divided into a plurality of sections by partitioning members. These sections function to prevent excess deformation or replacement of the fillers upon occurrence of falling accident. Since the shock absorbing small pieces in the shock absorbing vessel are filled irregularly, shock absorbing characteristics such as compression strength is not varied depending on the direction, but they exhibit excellent shock absorbing performance. They surely absorb shocks exerted on a transportation vessel upon falling or the like. If existing artificial fillers such as pole rings made of metal or ceramic and cut pieces such as alumium extrusion molding products are used as the shock absorbing pieces, they have excellent fire-proofness and cold resistance since the small pieces are inflammable and do not contain water. (T.M.)

Modeling and evaluation of HE driven shock effects in copper with the MTS model

International Nuclear Information System (INIS)

Murphy, M.J.; Lassila, D.F.

1997-01-01

Many experimental studies have investigated the effect of shock pressure on the post-shock mechanical properties of OFHC copper. These studies have shown that significant hardening occurs during shock loading due to dislocation processes and twinning. It has been demonstrated that when an appropriate initial value of the Mechanical Threshold Stress (MTS) is specified, the post-shock flow stress of OFE copper is well described by relationships derived independently for unshocked materials. In this study we consider the evolution of the MTS during HE driven shock loading processes and the effect on the subsequent flow stress of the copper. An increased post shock flow stress results in a higher material temperature due to an increase in the plastic work. An increase in temperature leads to thermal softening which reduces the flow stress. These coupled effects will determine if there is melting in a shaped charge jet or a necking instability in an EFP Ww. 'Me critical factor is the evolution path followed combined with the 'current' temperature, plastic strain, and strain rate. Preliminary studies indicate that in simulations of HE driven shock with very high resolution zoning, the MTS saturates because of the rate dependence in the evolution law. On going studies are addressing this and other issues with the goal of developing a version of the MT'S model that treats HE driven, shock loading, temperature, strain, and rate effects apriori

Flow Strength of Shocked Aluminum in the Solid-Liquid Mixed Phase Region

Science.gov (United States)

Reinhart, William

2011-06-01

Shock waves have been used to determine material properties under high shock stresses and very-high loading rates. The determination of mechanical properties such as compressive strength under shock compression has proven to be difficult and estimates of strength have been limited to approximately 100 GPa or less in aluminum. The term ``strength'' has been used in different ways. For a Von-Mises solid, the yield strength is equal to twice the shear strength of the material and represents the maximum shear stress that can be supported before yield. Many of these concepts have been applied to materials that undergo high strain-rate dynamic deformation, as in uni-axial strain shock experiments. In shock experiments, it has been observed that the shear stress in the shocked state is not equal to the shear strength, as evidenced by elastic recompressions in reshock experiments. This has led to an assumption that there is a yield surface with maximum (loading)and minimum (unloading), shear strength yet the actual shear stress lies somewhere between these values. This work provides the first simultaneous measurements of unloading velocity and flow strength for transition of solid aluminum to the liquid phase. The investigation describes the flow strength observed in 1100 (pure), 6061-T6, and 2024 aluminum in the solid-liquid mixed phase region. Reloading and unloading techniques were utilized to provide independent data on the two unknowns (τc and τo) , so that the actual critical shear strength and the shear stress at the shock state could be estimated. Three different observations indicate a change in material response for stresses of 100 to 160 GPa; 1) release wave speed (reloading where applicable) measurements, 2) yield strength measurements, and 3) estimates of Poisson's ratio, all of which provide information on the melt process including internal consistency and/or non-equilibrium and rate-dependent melt behavior. The study investigates the strength properties

Experimental Study of the Effect of Water Mist Location On Blast Overpressure Attenuation in A Shock Tube

Science.gov (United States)

Mataradze, Edgar; Chikhradze, Nikoloz; Bochorishvili, Nika; Akhvlediani, Irakli; Tatishvili, Dimitri

2017-12-01

Explosion protection technologies are based on the formation of a shock wave mitigation barrier between the protection site and the explosion site. Contemporary protective systems use water mist as an extinguishing barrier. To achieve high effectiveness of the protective system, proper selection of water mist characteristics is important. The main factors defining shock wave attenuation in water mist include droplet size distribution, water concentration in the mist, droplet velocity and geometric properties of mist. This paper examines the process of attenuation of shock waves in mist with droplets ranging from 25 to 400 microns under different conditions of water mist location. Experiments were conducted at the Mining Institute with the use of a shock tube to study the processes of explosion suppression by a water mist barrier. The shock tube consists of a blast chamber, a tube, a system for the dosed supply of water, sensors, data recording equipment, and a process control module. Shock wave overpressure reduction coefficient was studied in the shock tube under two different locations of water mist: a) when water mist is created in direct contact with blast chamber and b) the blast chamber and the mist are separated by air space. It is established that in conditions when the air space distance between the blast chamber and the mist is 1 meter, overpressure reduction coefficient is 1.5-1.6 times higher than in conditions when water mist is created in direct contact with blast chamber.

Laser Induced Shock Waves and Vaporization in Biological System and Material Science

National Research Council Canada - National Science Library

Gerstman, Bernard S

2008-01-01

.... We have developed a computational model that allows the calculation of damage resulting from a laser pulse of any duration or energy due to temperature rise, explosive bubble formation, and shock wave production...

Research on Formation Mechanism of Dynamic Response and Residual Stress of Sheet Metal Induced by Laser Shock Wave

Science.gov (United States)

Feng, Aixin; Cao, Yupeng; Wang, Heng; Zhang, Zhengang

2018-01-01

In order to reveal the quantitative control of the residual stress on the surface of metal materials, the relevant theoretical and experimental studies were carried out to investigate the dynamic response of metal thin plates and the formation mechanism of residual stress induced by laser shock wave. In this paper, the latest research trends on the surface residual stress of laser shock processing technology were elaborated. The main progress of laser shock wave propagation mechanism and dynamic response, laser shock, and surface residual stress were discussed. It is pointed out that the multi-scale characterization of laser and material, surface residual stress and microstructure change is a new hotspot in laser shock strengthening technology.

Study on Reflected Shock Wave/Boundary Layer Interaction in a Shock Tube

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Wook; Kim, Tae Ho; Kim, Heuy Dong [Andong Nat’l Univ., Andong (Korea, Republic of)

2017-07-15

The interaction between a shock wave and a boundary layer causes boundary layer separation, shock train, and in some cases, strong unsteadiness in the flow field. Such a situation is also observed in a shock tube, where the reflected shock wave interacts with the unsteady boundary layer. However, only a few studies have been conducted to investigate the shock train phenomenon in a shock tube. In the present study, numerical studies were conducted using the two-dimensional axisymmetric domain of a shock tube, and compressible Navier-Stokes equations were solved to clarify the flow characteristics of shock train phenomenon inside a shock tube. A detailed wave diagram was developed based on the present computational results, which were validated with existing experimental data.

Characteristics of shock propagation in high-strength cement mortar

Science.gov (United States)

Wang, Zhanjiang; Li, Xiaolan; Zhang, Ruoqi

2001-06-01

Planar impact experiments have been performed on high-strength cement mortar to determine characteristics of shock propagation.The experiments were conducted on a light-gas gun,and permanent-magnet particle velocity gages were used to obtain the sand of 0.5 3.5mm size.A bulk density of 2.31g/cm^3,and a compressive and tensile strength of 82MPa and 7.8MPa,respectively,were determined.Three kinds of experimental techniques were used,including the reverse ballistic configuration.These techniques effectively averaged the measured dynamic compression state over a sensibly large volume of the test sample.The impact velocities were controlled over a range of approximately 80m/s to 0.83km/s.Hugoniot equation of state data were obtained for the material over a pressure range of approximately 0.2 2.0GPa,and its nonlinear constitutive relation were analyzed.The experiment results show that,in higher pressure range provided in the experiment,the shock wave in the material splits into two components of an elastic and a plastic,with the Hugoniot elastic limit 0.4 0.5GPa and the precursor velocity about 4.7km/s,and the material presents a very strong nonlinear dynamic response,and its shock amplitude will greatly decrease in propagation.

Electrochemical Disinfection Feasibility Assessment Materials Evaluation for the International Space Station

Science.gov (United States)

Rodriquez, Branelle; Shindo, David; Montgomery, Eliza

2013-01-01

The International Space Station (ISS) Program recognizes the risk of microbial contamination in their potable and non-potable water sources. The end of the Space Shuttle Program limited the ability to send up shock kits of biocides in the event of an outbreak. Currently, the United States Orbital Segment water system relies primarily on iodine to mitigate contamination concerns, which has been successful in remediating the small cases of contamination documented. However, a secondary method of disinfection is a necessary investment for future space flight. Over the past year, NASA Johnson Space Center has investigated the development of electrochemically generated systems for use on the ISS. These systems include: hydrogen peroxide, ozone, sodium hypochlorite, and peracetic acid. To use these biocides on deployed water systems, NASA must understand of the effect these biocides have on current ISS materials prior to proceeding forward with possible on-orbit applications. This paper will discuss the material testing that was conducted to assess the effects of the biocides on current ISS materials.

Mitigation of Adverse Effects Caused by Shock Wave Boundary Layer Interactions Through Optimal Wall Shaping

Science.gov (United States)

Liou, May-Fun; Lee, Byung Joon

2013-01-01

It is known that the adverse effects of shock wave boundary layer interactions in high speed inlets include reduced total pressure recovery and highly distorted flow at the aerodynamic interface plane (AIP). This paper presents a design method for flow control which creates perturbations in geometry. These perturbations are tailored to change the flow structures in order to minimize shock wave boundary layer interactions (SWBLI) inside supersonic inlets. Optimizing the shape of two dimensional micro-size bumps is shown to be a very effective flow control method for two-dimensional SWBLI. In investigating the three dimensional SWBLI, a square duct is employed as a baseline. To investigate the mechanism whereby the geometric elements of the baseline, i.e. the bottom wall, the sidewall and the corner, exert influence on the flow's aerodynamic characteristics, each element is studied and optimized separately. It is found that arrays of micro-size bumps on the bottom wall of the duct have little effect in improving total pressure recovery though they are useful in suppressing the incipient separation in three-dimensional problems. Shaping sidewall geometry is effective in re-distributing flow on the side wall and results in a less distorted flow at the exit. Subsequently, a near 50% reduction in distortion is achieved. A simple change in corner geometry resulted in a 2.4% improvement in total pressure recovery.

Plastic flow in weak shock waves in uranium

International Nuclear Information System (INIS)

Tonks, D.L.

1992-01-01

Measurements of the particle velocity in weak shock waves in metals are available for a number of materials. These measurements use the laser interferometer or VISAR technique in conjunction with a plate impact experiment. These measurements are important for determining the elastic -- plastic behavior of materials at high strain rates. Strain rates up to 10 7 /s are measurable with this technique, while more conventional mechanical testing machines, such as the Hopkinson bar, achieve rates only up to about 10 4 /s. In this paper, the VISAR measurements of Grady on uranium are analyzed using the weak shock analysis of Wallace to extract the plastic and total strains, the deviatoric and total stresses, and the plastic strain rates. A brief error analysis of the results will be given. 7 refs

Astrophysically relevant radiatively cooled hypersonic bow shocks in nested wire arrays

Science.gov (United States)

Ampleford, David

2009-11-01

We have performed laboratory experiments which introduce obstructions into hypersonic plasma flows to study the formation of shocks. Astrophysical observations have demonstrated many examples of equivalent radiatively cooled bow shocks, for example the head of protostellar jets or supernova remnants passing through the interstellar medium or between discrete clumps in jets. Wire array z-pinches allow us to study quasi-planar radiatively cooled flows in the laboratory. The early stage of a wire array z-pinch implosion consists of a steady flow of the wire material towards the axis. Given a high rate of radiative cooling, these flows reach high sonic- Mach numbers, typically up to 5. The 2D nature of this configuration allows the insertion of obstacles into the flow, such as a concentric ``inner'' wire array, as has previously been studied for ICF research. Here we study the application of such a nested array to laboratory astrophysics where the inner wires act as obstructions perpendicular to the flow, and induce bow shocks. By varying the wire array material (W/Al), the significance of radiative cooling on these shocks can be controlled, and is shown to change the shock opening angle. As multiple obstructions are present, the experiments show the interaction of multiple bow shocks. It is also possible to introduce a magnetic field around the static object, increasing the opening angle of the shocks. Further experiments can be designed to control the flow density, magnetic field structure and obstruction locations. In collaboration with: S.V. Lebedev, M.E. Cuneo, C.A. Jennings, S.N. Bland, J.P. Chittenden, A. Ciardi, G.N. Hall, S.C. Bott, M. Sherlock, A. Frank, E. Blackman

Collisionless electrostatic shocks

DEFF Research Database (Denmark)

Andersen, H.K.; Andersen, S.A.; Jensen, Vagn Orla

1970-01-01

An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth......An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth...

Simulation on the shock attenuation behavior of coupled RHA and ...

African Journals Online (AJOL)

This paper presents the shock attenuation behavior of engineering materials namely Rolled Homogenous Armor (RHA) and sandwich composite when subject to blast loadings. Blast loading on sandwich composite structure and monolithic material are investigated using LSDYNA 3D with Arbitrary LagrangianEulerian ...

Computing the Dust Distribution in the Bow Shock of a Fast-moving, Evolved Star

NARCIS (Netherlands)

van Marle, A. -J; Meliani, Z.; Keppens, R.; Decin, L.

2011-01-01

We study the hydrodynamical behavior occurring in the turbulent interaction zone of a fast-moving red supergiant star, where the circumstellar and interstellar material collide. In this wind–interstellar-medium collision, the familiar bow shock, contact discontinuity, and wind termination shock

Costs of radon diagnostics and mitigation in school building

International Nuclear Information System (INIS)

Leovic, K.W.; Rector, H.; Nagda, N.

1992-01-01

To determine the costs of radon diagnostics and active soil depressurization (ASD) system installation in schools, seven radon mitigators with extensive experience in school buildings were surveyed. The cost data were determined by providing the mitigators with two scenarios of open-quotes typicalclose quotes school buildings with elevated radon levels. The questionnaire in schools: (1) Review Construction Plans, (2) Conduct Diagnostic Measurements, (3) Design Mitigation System, (4) Purchase ASD Material, and (5) Install and Checkout ASD System. Based on the results of this survey, it is estimated that the average cost of ASD diagnostics and mitigation in a typical school would be roughly $0.50 per ft 2 . However, these costs would be higher in schools with extensive subslab walls, very poor PFE, and lower in simple schools with very good PFE and no subslab barriers to communication. The variations in costs provided by the mitigators are primarily due to the influences of (1) experience and practices of the mitigation companies, (2) ASD system requirements as perceived by the respondents, and (3) the degree of involvement by the school system in the process

Planar shock focusing through perfect gas lens: First experimental demonstration

International Nuclear Information System (INIS)

Biamino, Laurent; Mariani, Christian; Jourdan, Georges; Houas, Lazhar; Vandenboomgaerde, Marc; Souffland, Denis

2014-01-01

When a shock wave crosses an interface between two materials, this interface becomes unstable and the Richtmyer-Meshkov instability develops. Such instability has been extensively studied in the planar case, and numerous results were presented during the previous workshops. But the Richtmyer-Meshkov (Richtmyer, 1960, 'Taylor Instability in Shock Acceleration of Compressible Fluids,' Commun. Pure Appl. Math., 13(2), pp. 297-319; Meshkov, 1969, 'Interface of Two Gases Accelerated by a Shock Wave,' Fluid Dyn., 4(5), pp. 101-104) instability also occurs in a spherical case where the convergence effects must be taken into account. As far as we know, no conventional (straight section) shock tube facility has been used to experimentally study the Richtmyer-Meshkov instability in spherical geometry. The idea originally proposed by Dimotakis and Samtaney (2006, 'Planar Shock Cylindrical Focusing by a Perfect-Gas Lens,' Phys. Fluid., 18(3), pp. 031705-031708) and later generalized by Vandenboomgaerde and Aymard (2011, 'Analytical Theory for Planar Shock Focusing Through Perfect Gas Lens and Shock Tube Experiment Designs,' Phys. Fluid., 23(1), pp. 016101-016113) was to retain the flexibility of a conventional shock tube to convert a planar shock wave into a cylindrical one through a perfect gas lens. This can be done when a planar shock wave passes through a shaped interface between two gases. By coupling the shape with the impedance mismatch at the interface, it is possible to generate a circular transmitted shock wave. In order to experimentally check the feasibility of this approach, we have implemented the gas lens technique on a conventional shock tube with the help of a convergent test section, an elliptic stereo lithographed grid, and a nitrocellulose membrane. First experimental sequences of Schlieren images have been obtained for an incident shock wave Mach number equal to 1.15 and an air/SF_6-shaped interface. Experimental results indicate that the shock that moves

Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kang, Zhitao [Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332-0826 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Banishev, Alexandr A.; Christensen, James; Dlott, Dana D. [School of Chemical Sciences and Fredrick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Lee, Gyuhyon; Scripka, David A.; Breidenich, Jennifer; Summers, Christopher J.; Thadhani, Naresh N., E-mail: naresh.thadhani@mse.gatech.edu [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Xiao, Pan [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Zhou, Min [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States)

2016-07-28

The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

International Nuclear Information System (INIS)

Kang, Zhitao; Banishev, Alexandr A.; Christensen, James; Dlott, Dana D.; Lee, Gyuhyon; Scripka, David A.; Breidenich, Jennifer; Summers, Christopher J.; Thadhani, Naresh N.; Xiao, Pan; Zhou, Min

2016-01-01

The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

Rayleigh-Taylor stability for a shock wave-density discontinuity interaction

International Nuclear Information System (INIS)

Fraley, G.S.

1981-01-01

Shells in inertial fusion targets are typically accelerated and decelerated by two or three shocks followed by continuous acceleration. The analytic solution for perturbation growth of a shock wave striking a density discontinuity in an inviscid fluid is investigated. The Laplace transform of the solution results in a functional equation, which has a simple solution for weak shock waves. The solution for strong shock waves may be given by a power series. It is assumed that the equation of state is given by a gamma law. The four independent parameters of the solution are the gamma values on each side of the material interface, the density ratio at the interface, and the shock strength. The asymptotic behavior (for large distances and times) of the perturbation velocity is given. For strong shocks the decay of the perturbation away from the interface is much weaker than the exponential decay of an incompressible fluid. The asymptotic value is given by a constant term and a number of slowly decaying discreet frequencies. The number of frequencies is roughly proportional to the logarithm of the density discontinuity divided by that of the shock strength. The asymptotic velocity at the interface is tabulated for representative values of the independent parameters. For weak shocks the solution is compared with results for an incompressible fluid. The range of density ratios with possible zero asymptotic velocities is given

In situ measurement of plasma and shock wave properties inside laser-drilled metal holes

Science.gov (United States)

Brajdic, Mihael; Hermans, Martin; Horn, Alexander; Kelbassa, Ingomar

2008-10-01

High-speed imaging of shock wave and plasma dynamics is a commonly used diagnostic method for monitoring processes during laser material treatment. It is used for processes such as laser ablation, cutting, keyhole welding and drilling. Diagnosis of laser drilling is typically adopted above the material surface because lateral process monitoring with optical diagnostic methods inside the laser-drilled hole is not possible due to the hole walls. A novel method is presented to investigate plasma and shock wave properties during the laser drilling inside a confined environment such as a laser-drilled hole. With a novel sample preparation and the use of high-speed imaging combined with spectroscopy, a time and spatial resolved monitoring of plasma and shock wave dynamics is realized. Optical emission of plasma and shock waves during drilling of stainless steel with ns-pulsed laser radiation is monitored and analysed. Spatial distributions and velocities of shock waves and of plasma are determined inside the holes. Spectroscopy is accomplished during the expansion of the plasma inside the drilled hole allowing for the determination of electron densities.

A physical tool for severe accident mitigation studies

Energy Technology Data Exchange (ETDEWEB)

Marie, N., E-mail: nathalie.marie@cea.fr [CEA, DEN, DER, F-13108 Saint Paul Lez Durance (France); Bachrata, A. [CEA, DEN, DER, F-13108 Saint Paul Lez Durance (France); Seiler, J.M. [CEA, DEN, DTN, F-38054 Grenoble (France); Barjot, F. [EDF R& D, SINETICS, F-93141 Clamart (France); Marrel, A. [CEA, DEN, DER, F-13108 Saint Paul Lez Durance (France); Gossé, S. [CEA, DEN, DPC, F-91191 Gif Sur Yvette (France); Bertrand, F. [CEA, DEN, DER, F-13108 Saint Paul Lez Durance (France)

2016-12-01

Highlights: • Physical tool for mitigation studies devoted to SFR safety. • Physical models to describe the material discharge from core. • Comparison to SIMMER III results. • Studies for ASTRID safety assessment and support to core design. - Abstract: Within the framework of the Generation IV Sodium-cooled Fast Reactors (SFR) R&D program of CEA, the core behavior in case of severe accidents is being assessed. Such transients are usually simulated with mechanistic codes (such as SIMMER-III). As a complement to this code, which gives reference accidental transient, a physico-statistical approach is currently followed; its final objective being to derive the variability of the main results of interest for the safety. This approach involves a fast-running simulation of extended accident sequences coupling low-dimensional physical models to advanced statistical analysis techniques. In this context, this paper presents such a low-dimensional physical tool (models and simulation results) dedicated to molten core materials discharge. This 0D tool handles heat transfers from molten (possibly boiling) pools, fuel crust evolution, phase separation/mixing of fuel/steel pools, radial thermal erosion of mitigation tubes, discharge of core materials and associated axial thermal erosion of mitigation tubes. All modules are coupled with a global neutronic evolution model of the degraded core. This physical tool is used to study and to define mitigation features (function of tubes devoted to mitigation inside the core, impact of absorbers falling into the degraded core…) to avoid energetic core recriticality during a secondary phase of a potential severe accident. In the future, this physical tool, associated to statistical treatments of the effect of uncertainties would enable sensitivity analysis studies. This physical tool is described before presenting its comparison against SIMMER-III code results, including a space-and energy-dependent neutron transport kinetic

Shock waves in P-bar target

Energy Technology Data Exchange (ETDEWEB)

Tang, Zhijing; Anderson, K.

1991-11-01

The deposition of large amount of beam energy in short time will cause high temperature and pressure in the center of P-bar Target, and this disturbance will propagate outwards as a shock wave. Shock wave induced material changes which are of our concern include void growth and accompanying density decrease which will decrease antiproton yield, and crack formation and fracture as was observed in tungsten target which will destroy the integrity of the target. Our objective is to analyze the shock wave behavior in the target, optimize its design so that the destructive effects of shock wave can be minimized, the integrity of the target can be maintained, and a reasonably high yield of antiproton production can be achieved. In this report we put together some results of our analysis of a cylindrical copper target. We hope that it will provide a general overview of the shock wave phenomena in the target, establish a basis for further research, and facilitate the target design. First, energy deposition data are analyzed, and it is justified that as an approximation, the problem can be treated as axi-symmetric. The average data therefore are used as energy profile, however, the maximum energy deposition are still used as the peak value. Next some basic estimations are made as to what temperature and pressure can reach at present level of energy deposition. Then some characteristics of wave propagation in a thermal shock loaded solid are illustrated with a one-dimensional model. Since there is no analytical solution available for cylindrical geometry, our understanding of the problem relies on numerical model, which are performed via finite element package ANSYS. results of numerical analysis are summarized, sources of potential danger are identified, and design ideas to minimize the damage are proposed.

Shock waves in P-bar target

International Nuclear Information System (INIS)

Tang, Zhijing; Anderson, K.

1991-11-01

The deposition of large amount of beam energy in short time will cause high temperature and pressure in the center of P-bar Target, and this disturbance will propagate outwards as a shock wave. Shock wave induced material changes which are of our concern include void growth and accompanying density decrease which will decrease antiproton yield, and crack formation and fracture as was observed in tungsten target which will destroy the integrity of the target. Our objective is to analyze the shock wave behavior in the target, optimize its design so that the destructive effects of shock wave can be minimized, the integrity of the target can be maintained, and a reasonably high yield of antiproton production can be achieved. In this report we put together some results of our analysis of a cylindrical copper target. We hope that it will provide a general overview of the shock wave phenomena in the target, establish a basis for further research, and facilitate the target design. First, energy deposition data are analyzed, and it is justified that as an approximation, the problem can be treated as axi-symmetric. The average data therefore are used as energy profile, however, the maximum energy deposition are still used as the peak value. Next some basic estimations are made as to what temperature and pressure can reach at present level of energy deposition. Then some characteristics of wave propagation in a thermal shock loaded solid are illustrated with a one-dimensional model. Since there is no analytical solution available for cylindrical geometry, our understanding of the problem relies on numerical model, which are performed via finite element package ANSYS. results of numerical analysis are summarized, sources of potential danger are identified, and design ideas to minimize the damage are proposed

Transport in aluminized RDX under shock compression explored using molecular dynamics simulations

International Nuclear Information System (INIS)

Losada, M; Chaudhuri, S

2014-01-01

Shock response of energetic materials is controlled by a combination of mechanical response, thermal, transport, and chemical properties. How these properties interplay in condensed-phase energetic materials is of fundamental interest for improving predictive capabilities. Due to unknown nature of chemistry during the evolution and growth of high-temperature regions within the energetic material (so called hot spots), the connection between reactive and unreactive equations of state contain a high degree of empiricism. In particular, chemistry in materials with high degree of heterogeneity such as aluminized HE is of interest. In order to identify shock compression states and transport properties in high-pressure/temperature (HP-HT) conditions, we use molecular dynamics (MD) simulations in conjunction with the multi-scale shock technique (MSST). Mean square displacement calculations enabled us to track the diffusivity of stable gas products. Among decomposition products, H 2 O and CO 2 are found to be the dominant diffusing species under compression conditions. Heat transport and diffusion rates in decomposed RDX are compared and the comparison shows that around 2000 K, transport can be a major contribution during propagation of the reaction front.

Large-eddy simulation of passive shock-wave/boundary-layer interaction control

International Nuclear Information System (INIS)

Pasquariello, Vito; Grilli, Muzio; Hickel, Stefan; Adams, Nikolaus A.

2014-01-01

Highlights: • The present study investigates a passive flow-control technique for shock-wave/boundary-layer interaction. • The control configuration consists of local suction and injection through a pressure feedback duct. • Implicit LES have been conducted for three different suction locations. • Suction reduces the size of the separation zone. • Turbulence amplification and reflected shock dynamics can be significantly reduced. - Abstract: We investigate a passive flow-control technique for the interaction of an oblique shock generated by an 8.8° wedge with a turbulent boundary-layer at a free-stream Mach number of Ma ∞ =2.3 and a Reynolds number based on the incoming boundary-layer thickness of Re δ 0 =60.5×10 3 by means of large-eddy simulation (LES). The compressible Navier–Stokes equations in conservative form are solved using the adaptive local deconvolution method (ALDM) for physically consistent subgrid scale modeling. Emphasis is placed on the correct description of turbulent inflow boundary conditions, which do not artificially force low-frequency periodic motion of the reflected shock. The control configuration combines suction inside the separation zone and blowing upstream of the interaction region by a pressure feedback through a duct embedded in the wall. We vary the suction location within the recirculation zone while the injection position is kept constant. Suction reduces the size of the separation zone with strongest effect when applied in the rear part of the separation bubble. The analysis of wall-pressure spectra reveals that all control configurations shift the high-energy low-frequency range to higher frequencies, while the energy level is significantly reduced only if suction acts in the rear part of the separated zone. In that case also turbulence production within the interaction region is significantly reduced as a consequence of mitigated reflected shock dynamics and near-wall flow acceleration

Effects of Atwood number on shock focusing in shock-cylinder interaction

Science.gov (United States)

Ou, Junfeng; Ding, Juchun; Luo, Xisheng; Zhai, Zhigang

2018-02-01

The evolution of shock-accelerated heavy-gas cylinder surrounded by the air with different Atwood numbers (A_t=0.28, 0.50, 0.63) is investigated, concentrating on shock focusing and jet formation. Experimentally, a soap film technique is used to generate an ideal two-dimensional discontinuous gas cylinder with a clear surface, which can guarantee the observation of shock wave movements inside the cylinder. Different Atwood numbers are realized by different mixing ratios of SF_6 and air inside the cylinder. A high-speed schlieren system is adopted to capture the shock motions and jet morphology. Numerical simulations are also performed to provide more information. The results indicate that an inward jet is formed for low Atwood numbers, while an outward jet is generated for high Atwood numbers. Different Atwood numbers will lead to the differences in the relative velocities between the incident shock and the refraction shock, which ultimately results in the differences in shock competition near the downstream pole. The morphology and feature of the jet are closely associated with the position and intensity of shock focusing. The pressure and vorticity contours indicate that the jet formation should be attributed to the pressure pulsation caused by shock focusing, and the jet development is ascribed to the vorticity induction. Finally, a time ratio proposed in the previous work for determining the shock-focusing type is verified by experiments.

Monte Carlo study of neutrino acceleration in supernova shocks

International Nuclear Information System (INIS)

Kazanas, Demosthenes; Ellison, D.C.; National Aeronautics and Space Administration, Greenbelt, MD

1981-01-01

The first order Fermi acceleration mechanism of cosmic rays in shocks may be at work for neutrinos in supernova shocks when the latter are at densities rho>10 13 g cm -3 at which the core material is opaque to neutrinos. A Monte Carlo approach to study this effect is employed and the emerging neutrino power law spectra are presented. The increased energy acquired by the neutrinos may facilitate their detection in supernova explosions and provide information about the physics of collapse

Shock parameter calculations at weak interplanetary shock waves

Directory of Open Access Journals (Sweden)

J. M. Gloag

2005-02-01

Full Text Available A large set of interplanetary shock waves observed using the Ulysses spacecraft is analysed in order to determine their local parameters. For the first time a detailed analysis is extended to the thermodynamic properties of a large number of events. The intention is to relate the shock parameters to the requirements set by MHD shock theory. A uniform approach is adopted in the selection of up and downstream regions for this analysis and applied to all the shock waves. Initially, the general case of a 3 component adiabatic plasma is considered. However, the calculation of magnetosonic and Alfvénic Mach numbers and the ratio of downstream to upstream entropy produce some unexpected results. In some cases there is no clear increase in entropy across the shock and also the magnetosonic Mach number can be less than 1. It is found that a more discerning use of data along with an empirical value for the polytropic index can raise the distribution of downstream to upstream entropy ratios to a more acceptable level. However, it is also realised that many of these shocks are at the very weakest end of the spectrum and associated phenomena may also contribute to the explanation of these results.

DOE fundamentals handbook: Material science

International Nuclear Information System (INIS)

1993-01-01

This handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of the structure and properties of metals. This volume contains the following modules: thermal shock (thermal stress, pressurized thermal shock), brittle fracture (mechanism, minimum pressurization-temperature curves, heatup/cooldown rate limits), and plant materials (properties considered when selecting materials, fuel materials, cladding and reflectors, control materials, nuclear reactor core problems, plant material problems, atomic displacement due to irradiation, thermal and displacement spikes due to irradiation, neutron capture effect, radiation effects in organic compounds, reactor use of aluminum)

Double shock experiments and reactive flow modeling on LX-17 to understand the reacted equation of state

International Nuclear Information System (INIS)

Vandersall, Kevin S; Garcia, Frank; Fried, Laurence E; Tarver, Craig M

2014-01-01

Experimental data from measurements of the reacted state of an energetic material are desired to incorporate reacted states in modeling by computer codes. In a case such as LX-17 (92.5% TATB and 7.5% Kel-F by weight), where the time dependent kinetics of reaction is still not fully understood and the reacted state may evolve over time, this information becomes even more vital. Experiments were performed to measure the reacted state of LX-17 using a double shock method involving the use of two flyer materials (with known properties) mounted on the projectile that send an initial shock through the material close to or above the Chapman-Jouguet (CJ) state followed by a second shock at a higher magnitude into the detonated material. By measuring the parameters of the first and second shock waves, information on the reacted state can be obtained. The LX-17 detonation reaction zone profiles plus the arrival times and amplitudes of reflected shocks in LX-17 detonation reaction products were measured using Photonic Doppler Velocimetry (PDV) probes and an aluminum foil coated LiF window. A discussion of this work will include the experimental parameters, velocimetry profiles, data interpretation, reactive CHEETAH and Ignition and Growth modeling, as well as detail on possible future experiments.

Shock Mechanism Analysis and Simulation of High-Power Hydraulic Shock Wave Simulator

Directory of Open Access Journals (Sweden)

Xiaoqiu Xu

2017-01-01

Full Text Available The simulation of regular shock wave (e.g., half-sine can be achieved by the traditional rubber shock simulator, but the practical high-power shock wave characterized by steep prepeak and gentle postpeak is hard to be realized by the same. To tackle this disadvantage, a novel high-power hydraulic shock wave simulator based on the live firing muzzle shock principle was proposed in the current work. The influence of the typical shock characteristic parameters on the shock force wave was investigated via both theoretical deduction and software simulation. According to the obtained data compared with the results, in fact, it can be concluded that the developed hydraulic shock wave simulator can be applied to simulate the real condition of the shocking system. Further, the similarity evaluation of shock wave simulation was achieved based on the curvature distance, and the results stated that the simulation method was reasonable and the structural optimization based on software simulation is also beneficial to the increase of efficiency. Finally, the combination of theoretical analysis and simulation for the development of artillery recoil tester is a comprehensive approach in the design and structure optimization of the recoil system.

The electrochemistry of IGSCC mitigation

International Nuclear Information System (INIS)

Macdonald, D.D.

2002-01-01

A brief review is presented of the electrochemical mitigation of intergranular stress corrosion cracking (IGSCC) in watercooled reactor heat transport circuit structural materials. Electrochemical control and mitigation is possible because of the existence of a critical potential for intergranular stress corrosion cracking and due to the feasibility of modifying the environment to displace the corrosion potential to a value that is more negative than the critical value. However, even in cases where the corrosion potential cannot be displaced sufficiently in the negative direction to become more negative than the critical potential, considerable advantage is accrued, because of the roughly exponential dependence of the crack growth rate on potential. The most important parameters in affecting electrochemical control over the corrosion potential and crack growth rate are the kinetic parameters (exchange current densities and Tafel constants) for the redox reactions involving the principal radiolysis products of water (O 2 , H 2 H 2 O 2 ), external solution composition (concentrations of O 2 , H 2 O 2 , and H 2 ), flow velocity, and the conductivity of the bulk environment. The kinetic parameters for the redox reactions essentially determine the charge transfer impedance of the steel surface, which is shown to be one of the key parameters in affecting the magnitude of the coupling current and hence the crack growth rate. The exchange current densities, in particular, are amenable to control by catalysis or inhibition, with the result that surface modification techniques are highly effective in controlling and mitigating intergranular stress corrosion cracking in reactor coolant circuit materials. (orig.)

Effect of Surface Coatings on Cylinders Exposed to Underwater Shock

Directory of Open Access Journals (Sweden)

Y.W. Kwon

1994-01-01

Full Text Available The response of a coated cylinder (metallic cylinder coated with a rubber material subjected to an underwater explosion is analyzed numerically. The dynamic response of the coated cylinder appears to be adversely affected when impacted by an underwater shock wave under certain conditions of geometry and material properties of the coating. When adversely affected, significant deviations in values of axial stress, hoop stress, and strain are observed. The coated cylinder exhibits a larger deformation and higher internal energy in the metallic material. Rubber coatings appeared to inhibit energy dissipation from the metallic material to the surrounding water medium. A parametric study of various coatings was performed on both aluminum and steel cylinders. The adverse effect of the coating decreased when the stiffness of the rubber layer increased, indicating the existence of a threshold value. The results of this study indicate that the stiffness of the coating is a critical factor to the shock hardening of the coated cylinder.

Shock wave energy dissipation behavior (SWED) in Network forming ionic liquids (NILs): A Molecular dynamics study

Science.gov (United States)

Guda Vishnu, Karthik; Strachan, Alejandro

2017-06-01

SWED materials play a crucial role in protecting both personnel and structures in close proximity to blasts or ballistic impact. Exposure to shock waves with intensities as low as 1 MPa can cause brain injury in personnel and, hence, it is extremely important to understand the mechanisms operating in SWED materials and help design improved formulations. Recent experimental studies show that NILs containing di-ammonium cations and citrate anions with glass transition temperatures (Tg) below room temperature exhibit shockwave absorption characteristics that outperform polyurea (PU), a benchmark SWED assessment material. The experimentalists further hypothesized that the increased SWED ability in NILs with longer side chains (in di-ammonium cation) is due to a permanent structural ordering and nano-scale segregation. We use molecular dynamics simulations with the Dreiding force field to study shock propagation mechanisms in NILs. Shock propagation mechanisms in these materials are explored by performing both Hugoniostat and large scale non-equilibrium molecular dynamics (NEMD) simulations at 300 K. The simulation results show that the NIL 5-6 (5 C atoms (back bone) and 6 C atoms (side chain)) attenuates shocks better than NIL 5-3 (3 C atoms (side chain) and higher Tg) and PMMA in agreement with experimental observation. The simulations show that under shock loading the structures lose long range order; we find no evidence of nano-segregation nor or permanent structural changes.

Alfven shock trains

International Nuclear Information System (INIS)

Malkov, M.A.; Kennel, C.F.; Wu, C.C.; Pellat, R.; Shapiro, V.D.

1991-01-01

The Cohen--Kulsrud--Burgers equation (CKB) is used to consider the nonlinear evolution of resistive, quasiparallel Alfven waves subject to a long-wavelength, plane-polarized, monochromatic instability. The instability saturates by nonlinear steepening, which proceeds until the periodic waveform develops an interior scale length comparable to the dissipation length; a fast or an intermediate shock then forms. The result is a periodic train of Alfven shocks of one or the other type. For propagation strictly parallel to the magnetic field, there will be two shocks per instability wavelength. Numerical integration of the time-dependent CKB equation shows that an initial, small-amplitude growing wave asymptotes to a stable, periodic stationary wave whose analytic solution specifies how the type of shock embedded in the shock train, and the amplitude and speed of the shock train, depend on the strength and phase of the instability. Waveforms observed upstream of the Earth's bowshock and cometary shocks resemble those calculated here

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

Energy Technology Data Exchange (ETDEWEB)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Hohenberger, M.; Boehly, T. R. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Nikroo, A. [General Atomics, San Diego, California 92196 (United States)

2014-02-15

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

Science.gov (United States)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

2014-02-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

International Nuclear Information System (INIS)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J.; Hohenberger, M.; Boehly, T. R.; Nikroo, A.

2014-01-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing

Is shock index associated with outcome in children with sepsis/septic shock?*.

Science.gov (United States)

Yasaka, Yuki; Khemani, Robinder G; Markovitz, Barry P

2013-10-01

To investigate the association between PICU shock index (the ratio of heart rate to systolic blood pressure) and PICU mortality in children with sepsis/septic shock. To explore cutoff values for shock index for ICU mortality, how change in shock index over the first 6 hours of ICU admission is associated with outcome, and how the use of vasoactive therapy may affect shock index and its association with outcome. Retrospective cohort. Single-center tertiary PICU. Five hundred forty-four children with the diagnosis of sepsis/septic shock. None. From January 2003 to December 2009, 544 children met International Pediatric Sepsis Consensus Conference of 2005 criteria for sepsis/septic shock. Overall mortality was 23.7%. Among all patients, hourly shock index was associated with mortality: odds ratio of ICU mortality at 0 hour, 1.08, 95% CI (1.04-1.12); odds ratio at 1 hour, 1.09 (1.04-1.13); odds ratio at 2 hours, 1.09 (1.05-1.13); and odds ratio at 6 hours, 1.11 (1.06-1.15). When stratified by age, early shock index was associated with mortality only in children 1-3 and more than or equal to 12 years old. Area under the receiver operating characteristic curve in age 1-3 and more than or equal to 12 years old for shock index at admission was 0.69 (95% CI, 0.58-0.80) and 0.62 (95% CI, 0.52-0.72) respectively, indicating a fair predictive marker. Although higher shock index was associated with increased risk of mortality, there was no particular cutoff value with adequate positive or negative likelihood ratios to identify mortality in any age group of children. The improvement of shock index in the first 6 hours of ICU admission was not associated with outcome when analyzed in all patients. However, among patients whose shock index were above the 50th percentile at ICU admission for each age group, improvement of shock index was associated with lower ICU mortality in children between 1-3 and more than or equal to 12 years old (p = 0.02 and p = 0.03, respectively). When

Biomass shock pretreatment

Science.gov (United States)

Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.

2014-07-01

Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a shock event to produce a shocked biomass; and transferring the shocked biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring shocked biomass from the chamber.

The Shock and Vibration Digest. Volume 13, Number 3

Science.gov (United States)

1981-03-01

Matehal Structural ElemenU with Material Damping M.M. Wallace and C.W. Bert The Univ. of Oklahoma, Norman , OK, Shock Vib. Bull., U.S. Naval Res...Vibration Kxtremal Control Strategy D.O. Smallwood and D.L. Gregory Sandid Labs., Albuquerque, NM, Shock Vib. Bull., U.S. Ndvdl Res. Lab.. Proc., No...Smailey.AJ 656,700 Smallwood , D.0 683 Smith, D.R 517 Smith, I.M 655 Smith, S 534 Smith,! 622 Smolka.S.A 714 Solo.V 711 Sonnonburg, P.N 576

Effects of heat transfer coefficient treatments on thermal shock fracture prediction for LWR fuel claddings in water quenching

International Nuclear Information System (INIS)

Lee, Youho; Lee, Jeong Ik; Cheon, Hee

2015-01-01

Accurate modeling of thermal shock induced stresses has become ever most important to emerging accident-tolerant ceramic cladding concepts, such as silicon carbide (SiC) and SiC coated zircaloy. Since fractures of ceramic (entirely ceramic or coated) occur by excessive tensile stresses with linear elasticity, modeling transient stress distribution in the material provides a direct indication of the structural integrity. Indeed, even for the current zircaloy cladding material, the oxide layer formed on the surface - where cracks starts to develop upon water quenching - essentially behaves as a brittle ceramic. Hence, enhanced understanding of thermal shock fracture of a brittle material would fundamentally contribute to safety of nuclear reactors for both the current fuel design and that of the coming future. Understanding thermal shock fracture of a brittle material requires heat transfer rate between the solid and the fluid for transient temperature fields of the solid, and structural response of the solid under the obtained transient temperature fields. In water quenching, a solid experiences dynamic time-varying heat transfer rates with phase changes of the fluid over a short quenching period. Yet, such a dynamic change of heat transfer rates during the water quenching transience has been overlooked in assessments of mechanisms, predictability, and uncertainties for thermal shock fracture. Rather, a time-constant heat transfer coefficient, named 'effective heat transfer coefficient' has become a conventional input to thermal shock fracture analysis. No single constant heat transfer could suffice to depict the actual stress evolution subject to dynamic heat transfer coefficient changes with fluid phase changes. Use of the surface temperature dependent heat transfer coefficient will remarkably increase predictability of thermal shock fracture of brittle materials and complete the picture of stress evolution in the quenched solid. The presented result

Simultaneous X-ray imaging and diffraction study of shock propagation and phase transition in silicon

Science.gov (United States)

Galtier, Eric

2017-06-01

X-ray phase contrast imaging technique using a free electron laser have observed the propagation of laser-driven shock waves directly inside materials. While providing images with few hundred nanometers spatial resolution, access to more quantitative information like the material density and the various shock front speeds remain challenging due to imperfections in the images limiting the convergence in the reconstruction algorithm. Alternatively, pump-probe X-ray diffraction (XRD) is a robust technique to extract atomic crystalline structure of compressed matter, providing insight into the kinetics of phase transformation and material response to stress. However, XRD by itself is not sufficient to extract the equation of state of the material under study. Here we report on the use of the LCLS free electron laser as a source of a high-resolution X-ray microscopy enabling the direct imaging of shock waves and phase transitions in optically opaque silicon. In this configuration, no algorithm is necessary to extract the material density and the position of the shock fronts. Simultaneously, we probed the crystalline structure via XRD of the various phases in laser compressed silicon. E. Galtier, B. Nagler, H. J. Lee, S. Brown, E. Granados, A. Hashim, E. McBride, A. Mackinnon, I. Nam, J. Zimmerman (SLAC) A. Gleason (Stanford, LANL) A. Higginbotham (University of York) A. Schropp, F. Seiboth (DESY).

Exploration of the fragmentation of laser shock-melted aluminum using x-ray backlighting

Directory of Open Access Journals (Sweden)

Lin Zhang

2016-05-01

Full Text Available The fragmentation of shock-melted metal material is an important scientific problem in shock physics and is suitable for experimentally investigating by the laser-driven x-ray backlighting technique. This letter reports on the exploration of laser shock-melted aluminum fragmentation by means of x-ray backlighting at the SGII high energy facility in China. High-quality and high-resolution radiographs with negligible motion blur were obtained and these images enabled analysis of the mass distribution of the fragmentation product.

Elastic, Frictional, Strength and Dynamic Characteristics of the Bell Shape Shock Absorbers Made of MR Wire Material

Science.gov (United States)

Lazutkin, G. V.; Davydov, D. P.; Boyarov, K. V.; Volkova, T. V.

2018-01-01

The results of the mechanical characteristic experimental studies are presented for the shock absorbers of DKU type with the elastic elements of the bell shape made of MR material and obtained by the cold pressing of mutually crossing wire spirals with their inclusion in the array of reinforcing wire harnesses. The design analysis and the technology of MR production based on the methods of similarity theory and dimensional analysis revealed the dimensionless determined and determining parameters of elastic frictional, dynamic and strength characteristics under the static and dynamic loading of vibration isolators. The main similarity criteria of mechanical characteristics for vibration isolators and their graphical and analytical representation are determined, taking into account the coefficients of these (affine) transformations of the hysteresis loop family field.

The Effects of Oil Price Shocks on Turkish Business Cycle: A Markov Switching Approach

Directory of Open Access Journals (Sweden)

Vasif Abiyev

2015-10-01

Full Text Available Purpose - The purpose of this study is to investigate the relationship between oil price changes and the output growth in Turkey. Design/methodology/approach - The data were taken from International Financial Statistics databases, consisting of monthly data for the period 1986:01-2014:09. Different univariate Markov - switching regime autoregressive models are specified and estimated. Among them we selected univariate MSIH(3 - AR(2 model for output and extended it to verify if the inclusion of various asymmetric oil price shocks as an exogenous variable improves the ability of the Markov switching model. Four different oil price shocks are considered. Findings - We find that among various oil price shocks, only net oil price increases have negative effects on output growth and mitigate the magnitude of some recessionary periods in Turkey. However, it doesn’t strongly explain the behavior of business cycle in Turkey. Research limitations/implications - Our results suggest that the inclusion of other fundamental financial factors in the bivariate Markov switching model of aggregate economic activity and oil price changes becomes important to explicitly detect the negative impact of oil price shocks on output in Turkey. Originality/value - Our results support the existence of a negative relationship between oil price increases and output growth mentioned in the literature and empirical studies on Turkey.

Gamma-ray emission from internal shocks in novae

Science.gov (United States)

Martin, P.; Dubus, G.; Jean, P.; Tatischeff, V.; Dosne, C.

2018-04-01

Context. Gamma-ray emission at energies ≥100 MeV has been detected from nine novae using the Fermi Large Area Telescope (LAT), and can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which interaction of the ejecta with a tenuous circumbinary material is not expected to generate detectable gamma-ray emission. Aim. We examine whether particle acceleration at internal shocks can account for the gamma-ray emission from these novae. The shocks result from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the nova outburst. Methods: We present a one-dimensional model for the dynamics of a forward and reverse shock system in a nova ejecta, and for the associated time-dependent particle acceleration and high-energy gamma-ray emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. The predicted emission is compared to LAT observations of V407 Cyg, V1324 Sco, V959 Mon, V339 Del, V1369 Cen, and V5668 Sgr. Results: The ≥100 MeV gamma-ray emission arises predominantly from particles accelerated up to 100 GeV at the reverse shock and undergoing hadronic interactions in the dense cooling layer downstream of the shock. The emission rises within days after the onset of the wind, quickly reaches a maximum, and its subsequent decrease reflects mostly the time evolution of the wind properties. Comparison to gamma-ray data points to a typical scenario where an ejecta of mass 10-5-10-4 M⊙ expands in a homologous way with a maximum velocity of 1000-2000 km s-1, followed within a day by a wind with a velocity values of which result in the majority of best-fit models having gamma-ray spectra with a high-energy turnover below 10 GeV. Our typical model is able to account for the main

Cosmic-ray shock acceleration in oblique MHD shocks

Science.gov (United States)

Webb, G. M.; Drury, L. OC.; Volk, H. J.

1986-01-01

A one-dimensional, steady-state hydrodynamical model of cosmic-ray acceleration at oblique MHD shocks is presented. Upstream of the shock the incoming thermal plasma is subject to the adverse pressure gradient of the accelerated particles, the J x B force, as well as the thermal gas pressure gradient. The efficiency of the acceleration of cosmic-rays at the shock as a function of the upstream magnetic field obliquity and upstream plasma beta is investigated. Astrophysical applications of the results are briefly discussed.

Polyimide Nanocomposite Circuit Board Materials to Mitigate Internal Electrostatic Discharge, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — In Sub-topic T8.02, NASA has identified a need for improved circuit boards to mitigate the hazards of internal electrostatic discharge (IESD) on missions where high...

Comparison of acoustic shock waves generated by micro and nanosecond lasers for a smart laser surgery system

Science.gov (United States)

Nguendon Kenhagho, Hervé K.; Rauter, Georg; Guzman, Raphael; C. Cattin, Philippe; Zam, Azhar

2018-02-01

Characterization of acoustic shock wave will guarantee efficient tissue differentiation as feedback to reduce the probability of undesirable damaging (i.e. cutting) of tissues in laser surgery applications. We ablated hard (bone) and soft (muscle) tissues using a nanosecond pulsed Nd:YAG laser at 532 nm and a microsecond pulsed Er:YAG laser at 2.94 μm. When the intense short ns-pulsed laser is applied to material, the energy gain causes locally a plasma at the ablated spot that expands and propagates as an acoustic shock wave with a rarefaction wave behind the shock front. However, when using a μs-pulsed Er:YAG laser for material ablation, the acoustic shock wave is generated during the explosion of the ablated material. We measured and compared the emitted acoustic shock wave generated by a ns-pulsed Nd:YAG laser and a μs-pulsed Er:YAG laser measured by a calibrated microphone. As the acoustic shock wave attenuates as it propagates through air, the distance between ablation spots and a calibrated microphone was at 5 cm. We present the measurements on the propagation characteristics of the laser generated acoustic shock wave by measuring the arrival time-of-flight with a calibrated microphone and the energy-dependent evolution of acoustic parameters such as peak-topeak pressure, the ratio of the peak-to-peak pressures for the laser induced breakdown in air, the ablated muscle and the bone, and the spectral energy.

Shock compression synthesis of hard materials

Energy Technology Data Exchange (ETDEWEB)

Willson, C.G. [Univ. of Texas, Austin, TX (United States). Dept. of Chemistry

1999-03-01

The purpose of this research was to adapt the high explosives technology that was developed in conjunction with nuclear weapons programs to subjecting materials to ultra-high pressures and to explore the utility of this technique for the synthesis of hard materials. The research was conducted in collaboration with researchers at the University of Texas, Texas Tech University and Pantex (Mason and Hanger Corp.). The group designed, modeled, built, and tested a new device that allows quantitative recovery of grams of material that have been subjected to unprecedented pressures. The modeling work was done at Texas Tech and Pantex. The metal parts and material samples were made at the University of Texas, and Pantex machined the explosives, assembled the devices and conducted the detonations. Sample characterization was carried out at the University of Texas and Texas Tech.

Shock absorber system for nuclear reactor ice condenser compartment

International Nuclear Information System (INIS)

Meier, J.F.; Rudd, G.E.; Pradhan, A.V.; George, J.A.; Lippincott, H.W.; Sutherland, J.D.

1979-01-01

A shock absorber system was designed to absorb the energy imparted to doors in a nuclear reactor ice condenser compartment as they swing rapidly to an open position. Each shock absorber which is installed on a wall adjacent to each door is large and must absorb up to about 40,000 foot pounds of energy. The basic shock absorber component comprises foam enclosed in a synthetic fabric bag having a volume about twice the foam volume. A stainless steel knitted mesh bag of the same volume as the fabric bag, contains the fabric bag and its enclosed foam. To protect the foam and bags during construction activities at the reactor site and from the shearing action of the doors, a protective sheet metal cover is installed over the shock absorber ends and the surface to be contacted by the moving door. With the above shock absorber mounted on a wall behind each door, as the door is forcibly opened by steam pressure and air resulting from a pipe break in the reactor compartment, it swings at a high velocity into contact with the shock absorber, crushes the foam and forces it into the fabric bag excess material thus containing the foam fragmented particles, and minimizes build-up of pressure in the bag as a result of the applied compressive force

Survey of existing literature in the field of shock-absorbing materials with a view to subsequent adaptation of plastic deformation codes. Phase 1

International Nuclear Information System (INIS)

Draulans, J.; Fabry, J.P.; Lafontaine, I.; Richel, H.; Guyette, M.

1985-01-01

Shock-absorbing materials and structures can be used as part of the transport container structure or of the truck equipment. An extensive survey of the literature has provided much information. Investigation has been made to define the required experimental procedures necessary to measure the misssing material properties. Three codes had been selected: EURDYN, MARC-CDC and SAMCEF. For code evaluation, a schematic container model has been considered to serve as a benchmark for the evaluation of plastic deformation. For the shock-calculation, the container falls from a height of 9 meters along the direction of its cylinder axis on an unyielded flat surface. The EURDYN computer code, has been selected first as it is especially designed to handle dynamic problems, preferably plastic ones. Indeed, EURDYN uses an explicit integration scheme versus time, which makes it quite efficient to run short deformation processes such as absorber collapses. The SAMCEF computer code could not readily calculate the benchmark, also a visco-plastic flow model has been added to it. The MARC computer code was supposed to be a candidate to run shock-calculation but extensive computing time and engineering efforts would be required, it was replaced by the PLEXUS code. The results obtained using the SAMCEF programme confirm those obtained with EURDYN. The PLEXUS results are in between. The proposed benchmark calculation is at the border of the capabilities of the most advanced computer codes for plastic-dynamic calculations. Indeed, a complex energy absorption process seems to take place in a narrow region, moving versus time, where very large shape inversions occur. That requires an accurate modelling of the system in the deformed regions and a skilful choice of the numerical parameters of the computer run. The three tested codes gave qualitatively consistent results and confirm some scarce experimental results

Measurement of the equation of state of porous materials through the use of shock waves generated by laser radiation; Mesure de l'equation d'etat de materiaux poreux a l'aide d'ondes de choc generees par laser

Energy Technology Data Exchange (ETDEWEB)

Philippe, F

2001-12-15

This work aims at measuring the equation of state of porous plastic materials in the view of their use in inertial confinement fusion. We have experimentally determined the shock polar curve of TMPTA (C{sub 15}H{sub 20}O{sub 6}) by the use of the impedance matching technique. This technique is based on the simultaneous measurement of the shock velocities in the 2 materials composing the target. The shock polar curve has been drawn for pressures ranging from 10 kbar to 3 Mbar and densities from 20 mg/cm{sup 3} to 1.1 g/cm{sup 3}. The use of a slit sweep camera to assess the propagation of the shock wave through the target has limited the accuracy of the technique to 10%. Experimental results match well data provided by the Sesame tables that are broadly used by hydrodynamic codes. Nevertheless the statistical distribution of experimental points seems to show a lower compressibility of the foam that might be attributed to a slight pre-heating process or to the effect of the foam micro-structure on the shock wave propagation. In order to improve the accuracy of the method, an attempt was made to use an active doppler interferometric diagnostic to measure shock wave velocities. It has been showed that the shock wave front in the foam is reflecting enough to make this method relevant if we can overcome the difficulty of a high luminous background. Despite that, we have succeeded in measuring with high accuracy, a point of the shock polar curve for 800 mg/cm{sup 3} dense TMPTA. (A.C.)

Effect of input variability on the quality of laser shock processing

Energy Technology Data Exchange (ETDEWEB)

Arif, Abul Fazal M. [King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

2009-10-15

Laser shock processing (LSP) involves high-energy laser radiation combined with suitable overlays to generate highpressure pulses on the surface of the metal. The stress wave generated due to high pressure pulses propagates into the material causing the surface layer to yield and plastically deform, and thereby, develop a significant residual compressive stress in the surface region of the substrate material. The developed compressive stress field is beneficial to improve surface properties such as fatigue, wear, and corrosion. To improve the understanding of the shock hardening process, investigation into the physical processes involved is necessary. In the first part of this paper, the temporal variation in the pressure intensity and spot size is calculated by using a two-dimensional recoil pressure prediction model. Using an explicit non-linear FEA code, ANSYS LS-DYNA, the deformation behavior and residual stresses in the substrate material are predicted. In the second part, a probabilistic approach to the modeling and analysis of LSP is presented in this paper. Various factors that affect the probabilistic performance of the LSP are grouped into categories and a select number of factors known to be significant, for which the variability could be assessed, are modeled as random variables (such as recoil pressure, laser beam spot size, substrate material properties and others). The potential of the probabilistic approach in predicting the structural integrity of the laser-shocked components is addressed

Effect of input variability on the quality of laser shock processing

International Nuclear Information System (INIS)

Arif, Abul Fazal M.

2009-01-01

Laser shock processing (LSP) involves high-energy laser radiation combined with suitable overlays to generate highpressure pulses on the surface of the metal. The stress wave generated due to high pressure pulses propagates into the material causing the surface layer to yield and plastically deform, and thereby, develop a significant residual compressive stress in the surface region of the substrate material. The developed compressive stress field is beneficial to improve surface properties such as fatigue, wear, and corrosion. To improve the understanding of the shock hardening process, investigation into the physical processes involved is necessary. In the first part of this paper, the temporal variation in the pressure intensity and spot size is calculated by using a two-dimensional recoil pressure prediction model. Using an explicit non-linear FEA code, ANSYS LS-DYNA, the deformation behavior and residual stresses in the substrate material are predicted. In the second part, a probabilistic approach to the modeling and analysis of LSP is presented in this paper. Various factors that affect the probabilistic performance of the LSP are grouped into categories and a select number of factors known to be significant, for which the variability could be assessed, are modeled as random variables (such as recoil pressure, laser beam spot size, substrate material properties and others). The potential of the probabilistic approach in predicting the structural integrity of the laser-shocked components is addressed

Integral Field Spectroscopy of Balmer-dominated Shocks in the Magellanic Cloud Supernova Remnant N103B

Energy Technology Data Exchange (ETDEWEB)

Ghavamian, Parviz [Department of Physics, Astronomy and Geosciences, Towson University, Towson, MD 21252 (United States); Seitenzahl, Ivo R.; Dopita, M. A. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Vogt, Frédéric P. A. [European Southern Observatory, Av. Alonso de Córdova 3107, 763 0355 Vitacura, Santiago (Chile); Terry, Jason P. [Department of Physics and Astronomy, University of Georgia (United States); Williams, Brian J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Winkler, P. Frank, E-mail: pghavamian@towson.edu [Department of Physics, Middlebury College, Middlebury, VT 05753 (United States)

2017-10-01

We present results of integral field spectroscopy of Balmer-dominated shocks in the LMC supernova remnant (SNR) N103B, carried out using the Wide Field Integral Spectrograph (WiFeS ) on the 2.3 m telescope at the Siding Spring Observatory in Australia. Existing X-ray studies of N103B have indicated an SN Ia origin. Radiative shock emission from clumpy material surrounding the SNR may result from interaction of the forward shock with relic stellar wind material, possibly implicating a thermonuclear explosion in a single-degenerate binary system. The recently discovered Balmer-dominated shocks mark the impact of the forward shock with low density, partially neutral CSM gas, and form a partial shell encircling clumps of material exhibiting radiative shocks. The WiFeS spectra of N103B reveal broad H α emission having a width as high as 2350 km s{sup −1} along the northern rim, and both H α and H β broad profiles having widths around 1300 km s{sup −1} along the southern rim. Fits to the H α line profiles indicate that in addition to the usual broad and narrow emission components, a third component of intermediate width exists in these Balmer-dominated shocks, ranging from around 125 km s{sup −1} up to 225 km s{sup −1} in width. This is consistent with predictions of recent Balmer-dominated shock models, which predict that an intermediate-width component will be generated in a fast neutral precursor. We derive a Sedov age of approximately 685 ± 20 years for N103B from the Balmer-dominated spectra, consistent with the young age of 380–860 years estimated from light echo studies.

Microstructural characterisation of metallic shot peened and laser shock peened Ti–6Al–4V

International Nuclear Information System (INIS)

Lainé, Steven J.; Knowles, Kevin M.; Doorbar, Phillip J.; Cutts, Richard D.; Rugg, David

2017-01-01

A detailed analysis has been conducted of Ti–6Al–4V processed by metallic shot peening and laser shock peening. Analysis by incremental hole drilling, electron backscattered diffraction microscopy, transmission electron microscopy and transmission Kikuchi diffraction microscopy is evaluated and discussed. The results of this analysis highlight the very different dislocation structures in surfaces processed by these two techniques. Transmission Kikuchi diffraction also has been used to evaluate sub-grains generated by laser shock peening. A notable feature of material processed by laser shock peening is the almost complete absence of deformation twinning, contrasting with the frequent observation of extensive deformation twinning observed in the material processed by metallic shot peening.

Shock wave overtake measurements on cesium iodide

International Nuclear Information System (INIS)

Swenson, C.A.

1986-01-01

The luminosity of the shock front for CsI makes it an ideal material for which to measure directly sound velocities along the Hugoniot using shock wave overtake methods. In these measurements, the occurrence of melting along the Hugoniot is marked by a discontinuous decrease in the measured sound velocity. In addition, CsI is isoelectronic with xenon and is expected to begin to show metallic behavior along the Hugoniot near 0.9 Mbar. The directly-determined sound velocities and corresponding elastic moduli would be expected to be more sensitive to this transition than either Hugoniot equations of state or optical pyrometry experiments. This paper presents a brief description of the present experiments and results

Thermal shock properties of 2D-SiCf/SiC composites

International Nuclear Information System (INIS)

Lee, Sang Pill; Lee, Jin Kyung; Son, In Soo; Bae, Dong Su; Kohyama, Akira

2012-01-01

This paper dealt with the thermal shock properties of SiC f /SiC composites reinforced with two dimensional SiC fabrics. SiC f /SiC composites were fabricated by a liquid phase sintering process, using a commercial nano-size SiC powder and oxide additive materials. An Al 2 O 3 –Y 2 O 3 –SiO 2 powder mixture was used as a sintering additive for the consolidation of SiC matrix region. In this composite system, Tyranno SA SiC fabrics were also utilized as a reinforcing material. The thermal shock test for SiC f /SiC composites was carried out at the elevated temperature. Both mechanical strength and microstructure of SiC f /SiC composites were investigated by means of optical microscopy, SEM and three point bending test. SiC f /SiC composites represented a dense morphology with a porosity of about 8.2% and a flexural strength of about 160 MPs. The characterization of SiC f /SiC composites was greatly affected by the history of cyclic thermal shock. Especially, SiC f /SiC composites represented a reduction of flexural strength at the thermal shock temperature difference higher than 800 °C.

Radon mitigation experience in difficult-to-mitigate schools

International Nuclear Information System (INIS)

Leovic, K.W.; Craig, A.B.

1990-01-01

Initial radon mitigation experience in schools has shown sub-slab depressurization (SSD) to be generally effective in reducing elevated levels of radon in schools that have a continuous layer of clean, coarse aggregate underneath the slab. However, mitigation experience is limited in schools without sub-slab aggregate and in schools with characteristics such as return-air ductwork underneath the slab or unducted return-air plenums in the drop ceiling that are open to the sub-slab area (via open tops of block walls). Mitigation of schools with utility tunnels and of schools constructed over crawl spaces is also limited. Three Maryland schools exhibiting some of the above characteristics are being researched to help understand the mechanisms that control radon entry and mitigation in schools where standard SSD systems are not effective. This paper discusses specific characteristics of potentially difficult-to-mitigate schools and, where applicable, details examples from the three Maryland schools

Lightweight armor system

Science.gov (United States)

Chu, Henry S; Langhorst, Benjamin R; Bakas, Michael P; Thinnes, Gary L

2013-02-26

The disclosure provides a shock absorbing layer comprised of one or more shock absorbing cells, where a shock absorbing cell is comprised of a cell interior volume containing a plurality of hydrogel particles and a free volume, and where the cell interior volume is surrounded by a containing layer. The containing layer has a permeability such that the hydrogel particles when swollen remain at least partially within the cell interior volume when subjected to a design shock pressure wave, allowing for force relaxation through hydrogel compression response. Additionally, the permeability allows for the flow of exuded free water, further dissipating wave energy. In an embodiment, a plurality of shock absorbing cells is combined with a penetration resistant material to mitigate the transmitted shock wave generated by an elastic precursor wave in the penetration resistant material.

Shock melting method to determine melting curve by molecular dynamics: Cu, Pd, and Al.

Science.gov (United States)

Liu, Zhong-Li; Zhang, Xiu-Lu; Cai, Ling-Cang

2015-09-21

A melting simulation method, the shock melting (SM) method, is proposed and proved to be able to determine the melting curves of materials accurately and efficiently. The SM method, which is based on the multi-scale shock technique, determines melting curves by preheating and/or prepressurizing materials before shock. This strategy was extensively verified using both classical and ab initio molecular dynamics (MD). First, the SM method yielded the same satisfactory melting curve of Cu with only 360 atoms using classical MD, compared to the results from the Z-method and the two-phase coexistence method. Then, it also produced a satisfactory melting curve of Pd with only 756 atoms. Finally, the SM method combined with ab initio MD cheaply achieved a good melting curve of Al with only 180 atoms, which agrees well with the experimental data and the calculated results from other methods. It turned out that the SM method is an alternative efficient method for calculating the melting curves of materials.

Shock melting method to determine melting curve by molecular dynamics: Cu, Pd, and Al

International Nuclear Information System (INIS)

Liu, Zhong-Li; Zhang, Xiu-Lu; Cai, Ling-Cang

2015-01-01

A melting simulation method, the shock melting (SM) method, is proposed and proved to be able to determine the melting curves of materials accurately and efficiently. The SM method, which is based on the multi-scale shock technique, determines melting curves by preheating and/or prepressurizing materials before shock. This strategy was extensively verified using both classical and ab initio molecular dynamics (MD). First, the SM method yielded the same satisfactory melting curve of Cu with only 360 atoms using classical MD, compared to the results from the Z-method and the two-phase coexistence method. Then, it also produced a satisfactory melting curve of Pd with only 756 atoms. Finally, the SM method combined with ab initio MD cheaply achieved a good melting curve of Al with only 180 atoms, which agrees well with the experimental data and the calculated results from other methods. It turned out that the SM method is an alternative efficient method for calculating the melting curves of materials

Shock Producers and Shock Absorbers in the Crisis

OpenAIRE

Sinn, Hans-Werner

2009-01-01

It is not surprising that the U.S. has been by far the world’s largest shock producer in this crisis. The big shock absorbers on the other hand were Japan, Russia and Germany, whose exports shrank more than their imports.

Parametric study on the performance of automotive MR shock absorbers

Science.gov (United States)

Gołdasz, J.; Dzierżek, S.

2016-09-01

The paper contains the results of a parametric study to explore the influence of various quantities on the performance range of semi-active automotive shock absorbers using the magnetorheological (MR) fluid under steady-state and transient excitations. The analysis was performed with simulated data and using a standard single-tube shock absorber configuration with a single-gap MR valve. Additionally, the impact of material variables and valves geometry was examined as the parameters were varied and its dynamic range studied.

Shock loading predictions from application of indicial theory to shock-turbulence interactions

Science.gov (United States)

Keefe, Laurence R.; Nixon, David

1991-01-01

A sequence of steps that permits prediction of some of the characteristics of the pressure field beneath a fluctuating shock wave from knowledge of the oncoming turbulent boundary layer is presented. The theory first predicts the power spectrum and pdf of the position and velocity of the shock wave, which are then used to obtain the shock frequency distribution, and the pdf of the pressure field, as a function of position within the interaction region. To test the validity of the crucial assumption of linearity, the indicial response of a normal shock is calculated from numerical simulation. This indicial response, after being fit by a simple relaxation model, is used to predict the shock position and velocity spectra, along with the shock passage frequency distribution. The low frequency portion of the shock spectra, where most of the energy is concentrated, is satisfactorily predicted by this method.

Design and testing of a shock absorber for a type 1 container

International Nuclear Information System (INIS)

Sappok, M.; Beine, B.; Rittscher, D.

1993-01-01

A shock-absorber will be required for a rad. waste 'Konrad' type 1 container made of ductile cast iron whenever it will be used as a type B container according to the IAEA-Regulations for the Safe Transport of Radioactive materials. The shock-absorber has to protect the type B container during shipping such as to withstand the accident scenarios that are covered by the IAEA-Regulation tests without substantial loss of its shielding and tightness functions. The designation as type 1 container originates from German regulations for the intermediate storage site Gorleben and the final depository Konrad-mine. These regulations call for the limits on outside dimensions of 1700 mm in length, 1600 mm in width and 1450 mm in height as well as for a limit of 20 Mg on total weight without shock-absorber. The relatively simple design method for the shock-absorber has been validated by the test results. It can be extended to other materials and designs for shock-absorbers if reliable force-displacement-diagrams are available for the structural elements from which the absorbed energy and the displacements can be calculated by integration. In order to account for the dynamic effects, the better approximation of the true duration of the impact would be helpful. The present limit of 0.5 R p0,2 on the nominal stresses should be discussed because the large number of tests on containers made of ductile cast iron that have been performed up to now have shown a substantial level of conservatism on this respect. The sharply tapered pipes on edge Kl of the shock-absorbers should be replaced by pipe bends. This will result in smaller accelerations and in an even higher level of protection of the container than effected by the tested shock-absorber

Shock and vibration environments for large shipping containers on rail cars and trucks

International Nuclear Information System (INIS)

Magnuson, C.F.; Wilson, L.T.

1977-06-01

The purpose of this study was to provide definitions of shock and vibration environment to which fissile material shipping containers may be exposed during normal shipment by truck and rail cars. The definitions of vibration, shock superimposed on vibration and rail coupling shock result from existing data. The dependence of shock environment, from rail coupling operations, on parameters like cargo weight and shock attenuation couplers was also studied using spring-mass models. These studies show that for rail cars equipped with standard draft gear, the cargo response decreases with increased cargo weight until the springs bottom out. For rail cars equipped with shock attenuation couplers, cargo weight has little effect on cargo response. The study also shows the importance of matching couplers and tiedown stiffnesses to decrease the cargo response. Vibration and shock data samples have been obtained during truck shipment of heavy cargo and the data will be presented in subsequent reports. Similar data need to be obtained for rail shipment of heavy cargo and during rail coupling operations with heavy cargo

Shock Isolation Elements Testing for High Input Loadings. Volume II. Foam Shock Isolation Elements.

Science.gov (United States)

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*EXPANDED PLASTICS, (*SHOCK(MECHANICS), REDUCTION), TEST METHODS, SHOCK WAVES, STRAIN(MECHANICS), LOADS(FORCES), MATHEMATICAL MODELS, NUCLEAR EXPLOSIONS, HARDENING.

Two-Dimensional Simulations of Electron Shock Ignition at the Megajoule Scale

Science.gov (United States)

Shang, W.; Betti, R.

2016-10-01

Shock ignition uses a late strong shock to ignite the hot spot of an inertial confinement fusion capsule. In the standard shock-ignition scheme, an ignitor shock is launched by the ablation pressure from a spike in laser intensity. Recent experiments on OMEGA have shown that focused beams with intensity up to 6 ×1015 W /cm2 can produce copious amounts of hot electrons. The hot electrons are produced by laser-plasma instabilities (LPI's) and can carry up to 15 % of the instantaneous laser power. Megajoule-scale targets will likely produce even more hot electrons because of the large plasma scale length. We show that it is possible to design ignition targets with low implosion velocities that can be shock ignited using LPI-generated hot electrons to obtain high energy gains. These designs are robust to low-mode asymmetries and they ignite even for highly distorted implosions. Electron shock ignition requires tens of kilojoules of hot electrons, which can only be produced on a large laser facility like the National Ignition Facility. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Elastic-plastic collapse of super-elastic shock waves in face-centered-cubic solids

International Nuclear Information System (INIS)

Zhakhovsky, Vasily V; Demaske, Brian J; Oleynik, Ivan I; Inogamov, Nail A; White, Carter T

2014-01-01

Shock waves in the [110] and [111] directions of single-crystal Al samples were studied using molecular dynamics (MD) simulations. Piston-driven simulations were performed to investigate the split shock-wave regime. At low piston velocities, the material is compressed initially to a metastable over-compressed elastic state leading to a super-elastic single shock wave. This metastable elastic state later collapses to a plastic state resulting in the formation of a two-wave structure consisting of an elastic precursor followed by a slower plastic wave. The single two-zone elastic-plastic shock-wave regime appearing at higher piston velocities was studied using moving window MD. The plastic wave attains the same average speed as the elastic precursor to form a single two-zone shock wave. In this case, repeated collapse of the highly over-compressed elastic state near the plastic shock front produces ultrashort triangle pulses that provide the pressure support for the leading elastic precursor.

Effects of heat transfer coefficient treatments on thermal shock fracture prediction for LWR fuel claddings in water quenching

Energy Technology Data Exchange (ETDEWEB)

Lee, Youho; Lee, Jeong Ik; Cheon, Hee [KAIST, Daejeon (Korea, Republic of)

2015-05-15

Accurate modeling of thermal shock induced stresses has become ever most important to emerging accident-tolerant ceramic cladding concepts, such as silicon carbide (SiC) and SiC coated zircaloy. Since fractures of ceramic (entirely ceramic or coated) occur by excessive tensile stresses with linear elasticity, modeling transient stress distribution in the material provides a direct indication of the structural integrity. Indeed, even for the current zircaloy cladding material, the oxide layer formed on the surface - where cracks starts to develop upon water quenching - essentially behaves as a brittle ceramic. Hence, enhanced understanding of thermal shock fracture of a brittle material would fundamentally contribute to safety of nuclear reactors for both the current fuel design and that of the coming future. Understanding thermal shock fracture of a brittle material requires heat transfer rate between the solid and the fluid for transient temperature fields of the solid, and structural response of the solid under the obtained transient temperature fields. In water quenching, a solid experiences dynamic time-varying heat transfer rates with phase changes of the fluid over a short quenching period. Yet, such a dynamic change of heat transfer rates during the water quenching transience has been overlooked in assessments of mechanisms, predictability, and uncertainties for thermal shock fracture. Rather, a time-constant heat transfer coefficient, named 'effective heat transfer coefficient' has become a conventional input to thermal shock fracture analysis. No single constant heat transfer could suffice to depict the actual stress evolution subject to dynamic heat transfer coefficient changes with fluid phase changes. Use of the surface temperature dependent heat transfer coefficient will remarkably increase predictability of thermal shock fracture of brittle materials and complete the picture of stress evolution in the quenched solid. The presented result

Laser shock ignition of porous silicon based nano-energetic films

International Nuclear Information System (INIS)

Plummer, A.; Gascooke, J.; Shapter, J.; Kuznetsov, V. A.; Voelcker, N. H.

2014-01-01

Nanoporous silicon films on a silicon wafer were loaded with sodium perchlorate and initiated using illumination with infrared laser pulses to cause laser thermal ignition and laser-generated shock waves. Using Photon Doppler Velocimetry, it was determined that these waves are weak stress waves with a threshold intensity of 131 MPa in the silicon substrate. Shock generation was achieved through confinement of a plasma, generated upon irradiation of an absorptive paint layer held against the substrate side of the wafer. These stress waves were below the threshold required for sample fracturing. Exploiting either the laser thermal or laser-generated shock mechanisms of ignition may permit use of pSi energetic materials in applications otherwise precluded due to their environmental sensitivity

Laser shock ignition of porous silicon based nano-energetic films

Energy Technology Data Exchange (ETDEWEB)

Plummer, A.; Gascooke, J.; Shapter, J. [School of Chemical and Physical Sciences, Flinders University, 5042, Bedford Park (Australia); Centre of Expertise in Energetic Materials (CEEM), Bedford Park (Australia); Kuznetsov, V. A., E-mail: nico.voelcker@unisa.edu.au, E-mail: Valerian.Kuznetsov@dsto.defence.gov.au [School of Chemical and Physical Sciences, Flinders University, 5042, Bedford Park (Australia); Centre of Expertise in Energetic Materials (CEEM), Bedford Park (Australia); Weapons and Combat Systems Division, Defence Science and Technology Organisation, Edinburgh 5111 (Australia); Voelcker, N. H., E-mail: nico.voelcker@unisa.edu.au, E-mail: Valerian.Kuznetsov@dsto.defence.gov.au [Mawson Institute, University of South Australia, 5095, Mawson Lakes (Australia)

2014-08-07

Nanoporous silicon films on a silicon wafer were loaded with sodium perchlorate and initiated using illumination with infrared laser pulses to cause laser thermal ignition and laser-generated shock waves. Using Photon Doppler Velocimetry, it was determined that these waves are weak stress waves with a threshold intensity of 131 MPa in the silicon substrate. Shock generation was achieved through confinement of a plasma, generated upon irradiation of an absorptive paint layer held against the substrate side of the wafer. These stress waves were below the threshold required for sample fracturing. Exploiting either the laser thermal or laser-generated shock mechanisms of ignition may permit use of pSi energetic materials in applications otherwise precluded due to their environmental sensitivity.

Predicting traffic volumes and estimating the effects of shocks in massive transportation systems.

Science.gov (United States)

Silva, Ricardo; Kang, Soong Moon; Airoldi, Edoardo M

2015-05-05

Public transportation systems are an essential component of major cities. The widespread use of smart cards for automated fare collection in these systems offers a unique opportunity to understand passenger behavior at a massive scale. In this study, we use network-wide data obtained from smart cards in the London transport system to predict future traffic volumes, and to estimate the effects of disruptions due to unplanned closures of stations or lines. Disruptions, or shocks, force passengers to make different decisions concerning which stations to enter or exit. We describe how these changes in passenger behavior lead to possible overcrowding and model how stations will be affected by given disruptions. This information can then be used to mitigate the effects of these shocks because transport authorities may prepare in advance alternative solutions such as additional buses near the most affected stations. We describe statistical methods that leverage the large amount of smart-card data collected under the natural state of the system, where no shocks take place, as variables that are indicative of behavior under disruptions. We find that features extracted from the natural regime data can be successfully exploited to describe different disruption regimes, and that our framework can be used as a general tool for any similar complex transportation system.

A nova outburst powered by shocks

Science.gov (United States)

Li, Kwan-Lok; Metzger, Brian D.; Chomiuk, Laura; Vurm, Indrek; Strader, Jay; Finzell, Thomas; Beloborodov, Andrei M.; Nelson, Thomas; Shappee, Benjamin J.; Kochanek, Christopher S.; Prieto, José L.; Kafka, Stella; Holoien, Thomas W.-S.; Thompson, Todd A.; Luckas, Paul J.; Itoh, Hiroshi

2017-10-01

Classical novae are runaway thermonuclear burning events on the surfaces of accreting white dwarfs in close binary star systems, sometimes appearing as new naked-eye sources in the night sky1. The standard model of novae predicts that their optical luminosity derives from energy released near the hot white dwarf, which is reprocessed through the ejected material2-5. Recent studies using the Fermi Large Area Telescope have shown that many classical novae are accompanied by gigaelectronvolt γ-ray emission6,7. This emission likely originates from strong shocks, providing new insights into the properties of nova outflows and allowing them to be used as laboratories for the study of the unknown efficiency of particle acceleration in shocks. Here, we report γ-ray and optical observations of the Milky Way nova ASASSN-16ma, which is among the brightest novae ever detected in γ-rays. The γ-ray and optical light curves show a remarkable correlation, implying that the majority of the optical light comes from reprocessed emission from shocks rather than the white dwarf8. The ratio of γ-ray to optical flux in ASASSN-16ma directly constrains the acceleration efficiency of non-thermal particles to be around 0.005, favouring hadronic models for the γ-ray emission9. The need to accelerate particles up to energies exceeding 100 gigaelectronvolts provides compelling evidence for magnetic field amplification in the shocks.

Transport containers for radioactive material

International Nuclear Information System (INIS)

Doroszlai, P.; Ferroni, F.

1984-01-01

A cylindrical container for the transportation of radioactive reactor elements includes a top end, a bottom end and a pair of removable outwardly curved shock absorbers, each including a double-shelled construction having an internal shell with a convex intrados configuration and an external shell with a convex extrados configuration, the shock absorbers being filled with a low density energy-absorbing material and mounted at the top end and the bottom end of the container, respectively, and each of the shock absorbers having a toroidal configuration, and deformable tubes disposed within the shock absorbers and extending in the axial direction of the container

Polarized bow shocks reveal features of the winds and environments of massive stars

Science.gov (United States)

Shrestha, Manisha

2018-01-01

Massive stars strongly affect their surroundings through their energetic stellar winds and deaths as supernovae. The bow shock structures created by fast-moving massive stars contain important information about the winds and ultimate fates of these stars as well as their local interstellar medium (ISM). Since bow shocks are aspherical, the light scattered in the dense shock material becomes polarized. Analyzing this polarization reveals details of the bow shock geometry as well as the composition, velocity, density, and albedo of the scattering material. With these quantities, we can constrain the properties of the stellar wind and thus the evolutionary state of the star, as well as the dust composition of the local ISM.In my dissertation research, I use a Monte Carlo radiative transfer code that I optimized to simulate the polarization signatures produced by both resolved and unresolved stellar wind bow shocks (SWBS) illuminated by a central star and by shock emission. I derive bow shock shapes and densities from published analytical calculations and smooth particle hydrodynamic (SPH) models. In the case of the analytical SWBS and electron scattering, I find that higher optical depths produce higher polarization and position angle rotations at specific viewing angles compared to theoretical predictions for low optical depths. This is due to the geometrical properties of the bow shock combined with multiple scattering effects. For dust scattering, the polarization signature is strongly affected by wavelength, dust grain properties, and viewing angle. The behavior of the polarization as a function of wavelength in these cases can distinguish among different dust models for the local ISM. In the case of SPH density structures, I investigate how the polarization changes as a function of the evolutionary phase of the SWBS. My dissertation compares these simulations with polarization data from Betelgeuse and other massive stars with bow shocks. I discuss the

Quasilinear simulations of interplanetary shocks and Earth's bow shock

Science.gov (United States)

Afanasiev, Alexandr; Battarbee, Markus; Ganse, Urs; Vainio, Rami; Palmroth, Minna; Pfau-Kempf, Yann; Hoilijoki, Sanni; von Alfthan, Sebastian

2016-04-01

We have developed a new self-consistent Monte Carlo simulation model for particle acceleration in shocks. The model includes a prescribed large-scale magnetic field and plasma density, temperature and velocity profiles and a self-consistently computed incompressible ULF foreshock under the quasilinear approximation. Unlike previous analytical treatments, our model is time dependent and takes full account of the anisotropic particle distributions and scattering in the wave-particle interaction process. We apply the model to the problem of particle acceleration at traveling interplanetary (IP) shocks and Earth's bow shock and compare the results with hybrid-Vlasov simulations and spacecraft observations. A qualitative agreement in terms of spectral shape of the magnetic fluctuations and the polarization of the unstable mode is found between the models and the observations. We will quantify the differences of the models and explore the region of validity of the quasilinear approach in terms of shock parameters. We will also compare the modeled IP shocks and the bow shock, identifying the similarities and differences in the spectrum of accelerated particles and waves in these scenarios. The work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA). The Academy of Finland is thanked for financial support. We acknowledge the computational resources provided by CSC - IT Centre for Science Ltd., Espoo.

Use of Silicon Carbide as Beam Intercepting Device Material: Tests, Issues and Numerical Simulations

CERN Document Server

Delonca, M; Gil Costa, M; Vacca, A

2014-01-01

Silicon Carbide (SiC) stands as one of the most promising ceramic material with respect to its thermal shock resistance and mechanical strengths. It has hence been considered as candidate material for the development of higher performance beam intercepting devices at CERN. Its brazing with a metal counterpart has been tested and characterized by means of microstructural and ultrasound techniques. Despite the positive results, its use has to be evaluated with care, due to the strong evidence in literature of large and permanent volumetric expansion, called swelling, under the effect of neutron and ion irradiation. This may cause premature and sudden failure, and can be mitigated to some extent by operating at high temperature. For this reason limited information is available for irradiation below 100°C, which is the typical temperature of interest for beam intercepting devices like dumps or collimators. This paper describes the brazing campaign carried out at CERN, the results, and the theoretical and numeric...

Release mitigation spray safety systems for chemical demilitarization applications.

Energy Technology Data Exchange (ETDEWEB)

Leonard, Jonathan; Tezak, Matthew Stephen; Brockmann, John E.; Servantes, Brandon; Sanchez, Andres L.; Tucker, Mark David; Allen, Ashley N.; Wilson, Mollye C.; Lucero, Daniel A.; Betty, Rita G.

2010-06-01

Sandia National Laboratories has conducted proof-of-concept experiments demonstrating effective knockdown and neutralization of aerosolized CBW simulants using charged DF-200 decontaminant sprays. DF-200 is an aqueous decontaminant, developed by Sandia National Laboratories, and procured and fielded by the US Military. Of significance is the potential application of this fundamental technology to numerous applications including mitigation and neutralization of releases arising during chemical demilitarization operations. A release mitigation spray safety system will remove airborne contaminants from an accidental release during operations, to protect personnel and limit contamination. Sandia National Laboratories recently (November, 2008) secured funding from the US Army's Program Manager for Non-Stockpile Chemical Materials Agency (PMNSCMA) to investigate use of mitigation spray systems for chemical demilitarization applications. For non-stockpile processes, mitigation spray systems co-located with the current Explosive Destruction System (EDS) will provide security both as an operational protective measure and in the event of an accidental release. Additionally, 'tented' mitigation spray systems for native or foreign remediation and recovery operations will contain accidental releases arising from removal of underground, unstable CBW munitions. A mitigation spray system for highly controlled stockpile operations will provide defense from accidental spills or leaks during routine procedures.

Two-dimensional study of shock breakout at the rear face of laser irradiated metallic targets

Energy Technology Data Exchange (ETDEWEB)

Cottet, F.; Marty, L.; Hallouin, M.; Romain, J.P.; Virmont, J.; Fabbro, R.; Faral, B.

1988-11-01

The two-dimensional propagation dynamics of laser-driven shock waves in solids is studied through the analysis of the shock breakout at the rear face of the target for a set of materials and laser intensities. The laser shock simulations were carried out by means of a two-dimensional hydrodynamics code in which the laser-ablation pressure is replaced by an equivalent pressure pulse. It is shown that the two-dimensional code is a very useful tool to analyze laser-shock experiments where two-dimensional effects arise from a finite laser-spot size or a heterogeneous energy deposition.

Two-dimensional study of shock breakout at the rear face of laser irradiated metallic targets

International Nuclear Information System (INIS)

Cottet, F.; Marty, L.; Hallouin, M.; Romain, J.P.; Virmont, J.; Fabbro, R.; Faral, B.

1988-01-01

The two-dimensional propagation dynamics of laser-driven shock waves in solids is studied through the analysis of the shock breakout at the rear face of the target for a set of materials and laser intensities. The laser shock simulations were carried out by means of a two-dimensional hydrodynamics code in which the laser-ablation pressure is replaced by an equivalent pressure pulse. It is shown that the two-dimensional code is a very useful tool to analyze laser-shock experiments where two-dimensional effects arise from a finite laser-spot size or a heterogeneous energy deposition

A primary standard for low-g shock calibration by laser interferometry

Science.gov (United States)

Sun, Qiao; Wang, Jian-lin; Hu, Hong-bo

2014-07-01

This paper presents a novel implementation of a primary standard for low-g shock acceleration calibration by laser interferometry based on rigid body collision at National Institute of Metrology, China. The mechanical structure of the standard device and working principles involved in the shock acceleration exciter, laser interferometers and virtual instruments are described. The novel combination of an electromagnetic exciter and a pneumatic exciter as the mechanical power supply of the standard device can deliver a wide range of shock acceleration levels. In addition to polyurethane rubber, two other types of material are investigated to ensure a wide selection of cushioning pads for shock pulse generation, with pulse shapes and data displayed. A heterodyne He-Ne laser interferometer is preferred for its precise and reliable measurement of shock acceleration while a homodyne one serves as a check standard. Some calibration results of a standard acceleration measuring chain are shown in company with the uncertainty evaluation budget. The expanded calibration uncertainty of shock sensitivity of the acceleration measuring chain is 0.8%, k = 2, with the peak acceleration range from 20 to 10 000 m s-2 and pulse duration from 0.5 to 10 ms. This primary shock standard can meet the traceability requirements of shock acceleration from various applications of industries from automobile to civil engineering and therefore is used for piloting the ongoing shock comparison of Technical Committee of Acoustics, Ultrasound and Vibration (TCAUV) of Asia Pacific Metrology Program (APMP), coded as APMP.AUV.V-P1.

A primary standard for low-g shock calibration by laser interferometry

International Nuclear Information System (INIS)

Sun, Qiao; Wang, Jian-lin; Hu, Hong-bo

2014-01-01

This paper presents a novel implementation of a primary standard for low-g shock acceleration calibration by laser interferometry based on rigid body collision at National Institute of Metrology, China. The mechanical structure of the standard device and working principles involved in the shock acceleration exciter, laser interferometers and virtual instruments are described. The novel combination of an electromagnetic exciter and a pneumatic exciter as the mechanical power supply of the standard device can deliver a wide range of shock acceleration levels. In addition to polyurethane rubber, two other types of material are investigated to ensure a wide selection of cushioning pads for shock pulse generation, with pulse shapes and data displayed. A heterodyne He–Ne laser interferometer is preferred for its precise and reliable measurement of shock acceleration while a homodyne one serves as a check standard. Some calibration results of a standard acceleration measuring chain are shown in company with the uncertainty evaluation budget. The expanded calibration uncertainty of shock sensitivity of the acceleration measuring chain is 0.8%, k = 2, with the peak acceleration range from 20 to 10 000 m s −2  and pulse duration from 0.5 to 10 ms. This primary shock standard can meet the traceability requirements of shock acceleration from various applications of industries from automobile to civil engineering and therefore is used for piloting the ongoing shock comparison of Technical Committee of Acoustics, Ultrasound and Vibration (TCAUV) of Asia Pacific Metrology Program (APMP), coded as APMP.AUV.V-P1. (paper)

Improved Reactive Flow Modeling of the LX-17 Double Shock Experiments

Science.gov (United States)

Rehagen, Thomas J.; Vitello, Peter

2017-06-01

Over driven double shock experiments provide a measurement of the properties of the reaction product states of the insensitive high explosive LX-17 (92.5% TATB and 7.5% Kel-F by weight). These experiments used two flyer materials mounted on the end of a projectile to send an initial shock through the LX-17, followed by a second shock of a higher magnitude into the detonation products. In the experiments, the explosive was initially driven by the flyer plate to pressures above the Chapman-Jouguet state. The particle velocity history was recorded by Photonic Doppler Velocimetry (PDV) probes pointing at an aluminum foil coated LiF window. The PDV data shows a sharp initial shock and decay, followed by a rounded second shock. Here, the experimental results are compared to 2D and 3D Cheetah reactive flow modeling. Our default Cheetah reactive flow model fails to accurately reproduce the decay of the first shock or the curvature or strength of the second shock. A new model is proposed in which the carbon condensate produced in the reaction zone is controlled by a kinetic rate. This allows the carbon condensate to be initially out of chemical equilibrium with the product gas. This new model reproduces the initial detonation peak and decay, and matches the curvature of the second shock, however, it still over-predicts the strength of the second shock. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Multiple spacecraft observations of interplanetary shocks Four spacecraft determination of shock normals

Science.gov (United States)

Russell, C. T.; Mellott, M. M.; Smith, E. J.; King, J. H.

1983-01-01

ISEE 1, 2, 3, IMP 8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for future investigations these data allow the evaluation of the accuracy of several shock normal determination techniques. When the angle between upstream and downstream magnetic field is greater than 20 deg, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, the use of overdetermined shock normal solutions, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints, is recommended whenever possible.

Pressure measurements and an analytical model for laser-generated shock waves in solids at low irradiance

International Nuclear Information System (INIS)

Romain, J P; Bonneau, F; Dayma, G; Boustie, M; Resseguier, T de; Combis, P

2002-01-01

Low amplitude shock waves (from 1 to 300 bar) have been generated in gold layers deposited on a quartz substrate, by laser pulses at an incident fluence from 0.4 to 4.0 J cm -2 . The quartz was used as a pressure gauge for recording the induced shock profile. At a fluence -2 , the shock pressure does not exceed 10 bar and the shock front is followed by a tension peak typical of an absorption in solid state. An analytical model of the compression-tension process has been developed, accounting for shock pressure and shock profile evolution as a function of irradiation conditions and material properties. From this model a mechanical interpretation is given to previous observations of spalling of the irradiated target surface

State of the art of mitigation and relation mitigation/adaptation

Energy Technology Data Exchange (ETDEWEB)

Lenstra, W.J.; Van Doorn, J.; Verheggen, B.; Sahan, E.; Boersma, A.R. [ECN Biomass, Coal and Environment Research, Petten (Netherlands)

2009-04-15

This study has the main purpose to make useful information available for the programming of the Knowledge for Climate (KfC) program. The emphasis has been laid on a broad overview of mitigation options and relations, complemented with more detailed information on new or less known options and insights. The mitigation option biomass gets special attention in this study. The production of biomass has many (positive and negative) relations with other elements of the KfC program like space use and adaptation. Recently a global discussion on biomass usage for biofuels has started (food or fuel). Therefore a separate chapter will be dedicated to the sustainability aspects of biomass. An overview of technical mitigation measures with emphasis on the energy supply side is presented. This overview shows the large number of available and innovative options and the vast potential for reduction of the emissions of Greenhouse Gases (GHG) of these mitigation measures. The effectiveness of many mitigation options is strongly dependent on local conditions and implementation issues. A number of innovative mitigation measures such as aquatic biomass and biomass in combination with Carbon Capture and Storage (CCS) are described in more detail. Biomass for energy has many different forms and applications. It is one of the mitigation options with a high potential, but at the same time it can have negative environmental impacts and might compete with other forms of land use including food production. This makes bio-energy a promising but complex option, which makes careful evaluation necessary. Several examples of multifunctional land use show that by combining functions, synergy can be achieved. This could lead to a reduction of potentially negative impacts and thus easier implementation. Furthermore, novel technologies for reducing or offsetting climate change such as air capture and artificial cooling might have a high potential as mitigation option, but need to be examined before

Are Credit Shocks Supply or Demand Shocks?

OpenAIRE

Bijapur, Mohan

2013-01-01

This paper provides new insights into the relationship between the supply of credit and the macroeconomy. We present evidence that credit shocks constitute shocks to aggregate supply in that they have a permanent effect on output and cause inflation to rise in the short term. Our results also suggest that the effects on aggregate supply have grown stronger in recent decades.

Miniature shock tube for laser driven shocks.

Science.gov (United States)

Busquet, Michel; Barroso, Patrice; Melse, Thierry; Bauduin, Daniel

2010-02-01

We describe in this paper the design of a miniature shock tube (smaller than 1 cm(3)) that can be placed in a vacuum vessel and allows transverse optical probing and longitudinal backside extreme ultraviolet emission spectroscopy in the 100-500 A range. Typical application is the study of laser launched radiative shocks, in the framework of what is called "laboratory astrophysics."

Mathematical Model of a Shim Valve of a Monotube Shock Absorber

Directory of Open Access Journals (Sweden)

Paulius Skačkauskas

2016-12-01

Full Text Available In the work, a mathematical model of a shim valve, used in monotube shock absorbers, designed to determine the deformations of the shims which form during the exploitation of the shock absorbers, is presented. The characteristic of the damping force formed by the shock absorber depends on the deformations. In the designed model, the amount, geometric dimensions, arrangement and the material properties of the shims are evaluated, and the contact forces, which form between the shims, are determined. The described model of the shim valve is presented in the environment of the software package MATLAB/Simulink, the analysis of the designed model is done using the software package ANSYS 15.0.

Coal mine subsidence: effects of mitigation on crop yields

International Nuclear Information System (INIS)

Darmody, R.G.; Hetzler, R.T.; Simmons, F.W.

1992-01-01

Subsidence from longwall underground coal mining adversely impacts agricultural land by creating wet or ponded areas. While most subsided areas show little impact, some localized places, usually less than 1.5 ha in size, may experience total crop failure. Coal companies mitigate subsidence damaged cropland by installing drainage waterways or by adding fill material to raise the grade. The objective of this study was to test the effectiveness of mitigation in restoring corn and soybean yields to pre-mined levels. Fourteen sites in southern Illinois were selected for study. Corn (Zea mays L.) and soybean (Glycine max L.) yields from mitigated and nearby undisturbed areas were compared for four years. Results varied due to differing weather and site conditions. Mean corn yields overall, however were significantly (α0.05) lower on mitigated areas. There was no significant difference in overall mean soybean yields. Soil fertility levels were similar and did not account for yield differences. 14 refs., 1 fig., 7 tabs

Investigation of Dynamic Friction Induced by Shock Loading Conditions

International Nuclear Information System (INIS)

Juanicotena, A.; Szarzynski, S.

2006-01-01

Modeling the frictional sliding of one surface against another under high pressure is often required to correctly describe the response of complex systems to shock loading. In order to provide data for direct code and model comparison, a new friction experiment investigating dry sliding characteristics of metal on metal at normal pressures up to 10 GPa and sliding velocities up to 400 m/s has been developed. The test consists of a specifically designed target made of two materials. A plane shock wave generated by plate impact results in one material sliding against the other. The material velocity of the rear surface of the target is recorded versus time by Doppler Laser Interferometry. The dynamic friction coefficient μ is then indirectly determined by comparison with results of numerical simulations involving the conventional Coulomb law. Using this new experimental configuration, three dynamic friction experiments were performed on AA 5083-Al (H111) / AISI 321 stainless steel tribo-pair. Results suggest a decrease in the friction coefficient with increasing sliding velocity

Scaling of Pressure with Intensity in Laser-Driven Shocks and Effects of Hot X-Ray Preheat

International Nuclear Information System (INIS)

Colvin, Jeffrey D.; Kalantar, Daniel H.

2006-01-01

To drive shocks into solids with a laser we either illuminate the material directly, or to get higher pressures, illuminate a plastic ablator that overlays the material of interest. In both cases the illumination intensity is low, <<1013 W/cm2, compared to that for traditional laser fusion targets. In this regime, the laser beam creates and interacts with a collisional, rather than a collisionless, plasma. We present scaling relationships for shock pressure with intensity derived from simulations for this low-intensity collisional plasma regime. In addition, sometimes the plastic-ablator targets have a thin flash-coating of Al on the plastic surface as a shine-through barrier; this Al layer can be a source of hot x-ray preheat. We discuss how the preheat affects the shock pressure, with application to simulating VISAR measurements from experiments conducted on various lasers on shock compression of Fe

Scaling of Pressure with Intensity in Laser-Driven Shocks and Effects of Hot X-ray Preheat

International Nuclear Information System (INIS)

Colvin, J D; Kalantar, D H

2005-01-01

To drive shocks into solids with a laser we either illuminate the material directly, or to get higher pressures, illuminate a plastic ablator that overlays the material of interest. In both cases the illumination intensity is low, 13 W/cm 2 , compared to that for traditional laser fusion targets. In this regime, the laser beam creates and interacts with a collisional, rather than a collisionless, plasma. We present scaling relationships for shock pressure with intensity derived from simulations for this low-intensity collisional plasma regime. In addition, sometimes the plastic-ablator targets have a thin flashcoating of Al on the plastic surface as a shine-through barrier; this Al layer can be a source of hot x-ray preheat. We discuss how the preheat affects the shock pressure, with application to simulating VISAR measurements from experiments conducted on various lasers on shock compression of Fe

Radiation- and pair-loaded shocks

Science.gov (United States)

Lyutikov, Maxim

2018-06-01

We consider the structure of mildly relativistic shocks in dense media, taking into account the radiation and pair loading, and diffusive radiation energy transfer within the flow. For increasing shock velocity (increasing post-shock temperature), the first important effect is the efficient energy redistribution by radiation within the shock that leads to the appearance of an isothermal jump, whereby the flow reaches the final state through a discontinuous isothermal transition. The isothermal jump, on scales much smaller than the photon diffusion length, consists of a weak shock and a quick relaxation to the isothermal conditions. Highly radiation-dominated shocks do not form isothermal jump. Pair production can mildly increase the overall shock compression ratio to ≈10 (4 for matter-dominated shocks and 7 of the radiation-dominated shocks).

Material Testing in Support of the ISS Electrochemical Disinfection Feasibility Study

Science.gov (United States)

Clements, Anna; Shindo, David; Modica, Cathy

2011-01-01

The International Space Station Program recognizes the risk of microbial contamination in their potable and non-potable water sources. With the end of the Space Shuttle Program, the ability to send up shock-kits of biocides in the event of an outbreak becomes even more difficult. Currently, the US Segment water system relies primarily on iodine to mitigate contamination concerns. To date, several small cases of contamination have occurred which have been remediated. NASA, however, realizes that having a secondary method of combating a microbial outbreak is a prudent investment. NASA is looking into developing hardware that can generate biocides electrochemically, and potentially deploying that hardware. The specific biocides that the technology could generate include: hydrogen peroxide, oxone, hypochlorite and peracetic acid. In order to use these biocides on deployed water systems, the project must determine that all the materials in the potential application are compatible with the biocides at their anticipated administered concentrations. This paper will detail the materials test portion of the feasibility assessment including the plan for both metals and non-metals along with results to date.

INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES

Directory of Open Access Journals (Sweden)

P. V. Bulat

2015-05-01

Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.

Shock/shock interactions between bodies and wings

Directory of Open Access Journals (Sweden)

Gaoxiang XIANG

2018-02-01

Full Text Available This paper examines the Shock/Shock Interactions (SSI between the body and wing of aircraft in supersonic flows. The body is simplified to a flat wedge and the wing is assumed to be a sharp wing. The theoretical spatial dimension reduction method, which transforms the 3D problem into a 2D one, is used to analyze the SSI between the body and wing. The temperature and pressure behind the Mach stem induced by the wing and body are obtained, and the wave configurations in the corner are determined. Numerical validations are conducted by solving the inviscid Euler equations in 3D with a Non-oscillatory and Non-free-parameters Dissipative (NND finite difference scheme. Good agreements between the theoretical and numerical results are obtained. Additionally, the effects of the wedge angle and sweep angle on wave configurations and flow field are considered numerically and theoretically. The influences of wedge angle are significant, whereas the effects of sweep angle on wave configurations are negligible. This paper provides useful information for the design and thermal protection of aircraft in supersonic and hypersonic flows. Keywords: Body and wing, Flow field, Hypersonic flow, Shock/shock interaction, Wave configurations

Decay of a laser generated shock wave in an aluminium target

International Nuclear Information System (INIS)

Werdiger, M.

1993-09-01

When a shock wave arrives at the near surface of a solid material, a radical and fast change occurs in the reflection properties of the material. The phenomenon is used in the present work in order to develop a new way to measure the transit time of a shock wave in a target. A 10 milliwatt He:Ne laser is directed toward the rear surface of the target. The reflected beam arrives at a photo-diode with a fast rise time of 150 psec which detects the instant of the change in the reflection. This technique, called 'continuous back lightning', is used in experiments with aluminium foil thickness in the range of 40μm ≤x≥ 1000μm. The shock wave is induced by a laser pulse of an intensity of 3*10 13 W/cm 2 . The results show two main physical regimes: in the first one 40μ ≤x≥ 210μm, there is a constant shock wave velocity which in our experiments was measured to be (12.81±0.67)km/s. In the second range of the thickness where 300μm there is a decay of the shock velocity. For x ≥ 210μm the geometry is one dimensional for our experimental conditions, while for x ≥ 300μm the 1-D geometry changes to 2 dimensional (2-D) geometry. The 2-D shock wave decay asymptotically (x→∞ to an acoustic wave. shock wave is described by a pressure scaling as x -n (n is a positive constant). The phenomenological equation of the state is taken to be P=A**u s + B*u s 2 +Bu s , where P is the pressure, u s - the shock velocity, A and B are constants. Applying our experimental results to the solution of the differential equation in this model A*x 2 ± B*x=C*x -n yields a value of n in the range 3.16 ≤n≥ 3.51. This pressure scaling law agrees with the self-similar solution of a concentrated impact on a surface between two media. This situation is well simulated by the laser deposition energy on a metal surface. In the experiment a 5% accuracy is achieved. Such a good accuracy has not been achieved so far in a laser induced shock-wave measurements in solids. (author). 52 refs

Molten fuel/coolant interaction studies: some results obtained with the Windscale small shock tube rig

International Nuclear Information System (INIS)

Higham, E.J.; Vaughan, G.J.

1978-02-01

Experiments are described in which water has been brought into contact with various molten metals in a shock tube, thus simulating the fall of coolant into molten uranium dioxide in a postulated reactor accident. Impact velocities of the water on to the molten material were in the range 5 to 7 m/s. Shock-pulse pressures in the water column after impact and particle size distributions of the dispersed resolidified material that was recovered were measured. The proportion of dispersed material and the size of the shock pulse (by comparison with that expected from water hammer alone) have been used as criteria for the occurrence of a molten fuel/coolant interaction and such interactions of varying degrees of violence have been found for water/aluminium, water/bismuth, water/tin, over a range of temperatures from 350 0 C to 950 0 C, for water/boric oxide, but not for water/magnesium. (author)

STEREO interplanetary shocks and foreshocks

Energy Technology Data Exchange (ETDEWEB)

Blanco-Cano, X. [Instituto de Geofisica, UNAM, CU, Coyoacan 04510 DF (Mexico); Kajdic, P. [IRAP-University of Toulouse, CNRS, Toulouse (France); Aguilar-Rodriguez, E. [Instituto de Geofisica, UNAM, Morelia (Mexico); Russell, C. T. [ESS and IGPP, University of California, Los Angeles, 603 Charles Young Drive, Los Angeles, CA 90095 (United States); Jian, L. K. [NASA Goddard Space Flight Center, Greenbelt, MD and University of Maryland, College Park, MD (United States); Luhmann, J. G. [SSL, University of California Berkeley (United States)

2013-06-13

We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and {theta}{sub Bn}{approx}20-86 Degree-Sign . We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr {<=}0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at {approx}1 AU and have been producing suprathermal particles for a shorter time.

STEREO interplanetary shocks and foreshocks

International Nuclear Information System (INIS)

Blanco-Cano, X.; Kajdič, P.; Aguilar-Rodríguez, E.; Russell, C. T.; Jian, L. K.; Luhmann, J. G.

2013-01-01

We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and θ Bn ∼20-86°. We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr ≤0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at ∼1 AU and have been producing suprathermal particles for a shorter time.

Collisionless shock waves

International Nuclear Information System (INIS)

Sagdeev, R.Z.; Kennel, C.F.

1991-01-01

Collisionless shocks cannot occur naturally on the earth, because nearly all matter here consists of electrically neutral atoms and molecules. In space, however, high temperatures and ultraviolet radiation from hot stars decompose atoms into their constituent nuclei and electrons, producing a soup of electrically charged particles known as a plasma. Plasma physicists proposed that the collective electrical and magnetic properties of plasmas could produce interactions that take the place of collisions and permit shocks to form. In 1964 the theoretical work found its first experimental confirmation. Norman F. Ness and his colleagues at the Goddard Space Flight Center, using data collected from the iMP-1 spacecraft, detected clear signs that a collisionless shock exists where the solar wind encounters the earth's magnetic field. More recent research has demonstrated that collisionless shocks appear in a dazzling array of astronomical settings. For example, shocks have been found in the solar wind upstream (sunward) of all the planet and comets that have been visited by spacecraft. Violent flares on the sun generate shocks that propagate to the far reaches of the solar system; tremendous galactic outbursts create disruptions in the intergalactic medium that are trillions of times larger. In addition, many astrophysicists think that shocks from supernova explosions in our galaxy accelerate cosmic rays, a class of extraordinarily energetic elementary particles and atomic nuclei that rain down on the earth from all directions

A High-Purity Alumina for Use in Studies of Shock Loaded Samples

Science.gov (United States)

Lacina, David; Neel, Christopher

2017-06-01

We report the results of plate impact experiments on a potential new ``standard'' material, Coorstek Plasmapure-UC (99.9% purity) polycrystalline alumina, for use in non-conduction, impact environment, shock loading studies. This work was motivated by a desire to find a 99.9% purity alumina to replace the now unavailable Coors Vistal (99.9%) alumina, as it was hoped the Hugoniot elastic limit (HEL) of the new standard would match the 9-11 GPa value of Vistal. Shock response data, including the HEL, Hugoniot particle velocities, Hugoniot shock velocities, stress vs volume, and release wave speeds, was obtained up to 14 GPa. This data will be compared with Hugoniot curve data for other high purity alumina to contrast differences in the shock response, and is intended to be useful in impedance matching calculations. We will show that the HEL of Plasmapure-UC alumina is 5.5 GPa and speculate on causes for this lower than expected value. We will also explore why the elastic-plastic response for Plasmapure-UC alumina differs from what has been observed from other high purity alumina. The final result of this work is to recommend a well-characterized, lower purity alumina (Coorstek AD-995) as a potential new ``standard'' material.

COMPUTING THE DUST DISTRIBUTION IN THE BOW SHOCK OF A FAST-MOVING, EVOLVED STAR

International Nuclear Information System (INIS)

Van Marle, A. J.; Meliani, Z.; Keppens, R.; Decin, L.

2011-01-01

We study the hydrodynamical behavior occurring in the turbulent interaction zone of a fast-moving red supergiant star, where the circumstellar and interstellar material collide. In this wind-interstellar-medium collision, the familiar bow shock, contact discontinuity, and wind termination shock morphology form, with localized instability development. Our model includes a detailed treatment of dust grains in the stellar wind and takes into account the drag forces between dust and gas. The dust is treated as pressureless gas components binned per grain size, for which we use 10 representative grain size bins. Our simulations allow us to deduce how dust grains of varying sizes become distributed throughout the circumstellar medium. We show that smaller dust grains (radius <0.045 μm) tend to be strongly bound to the gas and therefore follow the gas density distribution closely, with intricate fine structure due to essentially hydrodynamical instabilities at the wind-related contact discontinuity. Larger grains which are more resistant to drag forces are shown to have their own unique dust distribution, with progressive deviations from the gas morphology. Specifically, small dust grains stay entirely within the zone bound by shocked wind material. The large grains are capable of leaving the shocked wind layer and can penetrate into the shocked or even unshocked interstellar medium. Depending on how the number of dust grains varies with grain size, this should leave a clear imprint in infrared observations of bow shocks of red supergiants and other evolved stars.

Oil price shocks and economy: an open question

International Nuclear Information System (INIS)

Di Marzio, G.

2006-01-01

rise almost certainly reflects the strong global economic environment in which it occurs; the main factor mitigating adverse effects has been the sustained and autonomous expansion of the global economy. Large oil price fluctuations produce now smaller effects than in the previous decades; although oil price shocks have continued to Occur, there have been no major episodes of stagflation since the 1970s. Estimates confirm smaller effects of the Current price shock after taking into account the global decline in oil intensity of GDP and a better monetary policy management. Advanced consuming economies have become better adapted to deal with oil price increases and volatility; institutional characteristics of economic systems show simply less rigidities and regulations; the extent of inflation pass through from terms-of-trade shocks has declined in recent years as labour markets have become more flexible; energy-intensive manufacturing industries contribute less than before to real GDP formation. Ali these elements allow far faster adjustment processes. Since 2002 global macro economic conditions have been more favourable than in any previous period, with a primary role developed by monetary policy, whose moderate stance has been allowing far international real interest rates historically low, so sustaining global output growth and demand pressure on oil prices. But the experience subsequent the 1990s does not provide reasons far dismissing the risk that persistent oil price increases will pass through into core inflation, so pushing monetary conditions to change [it

Relativistic Shock Acceleration

International Nuclear Information System (INIS)

Duffy, P.; Downes, T.P.; Gallant, Y.A.; Kirk, J.G.

1999-01-01

In this paper we briefly review the basic theory of shock waves in relativistic hydrodynamics and magneto-hydrodynamics, emphasising some astrophysically interesting cases. We then present an overview of the theory of particle acceleration at such shocks describing the methods used to calculate the spectral indices of energetic particles. Recent results on acceleration at ultra-relativistic shocks are discussed. (author)

Improved bow shock models for Herbig-Haro objects - application to HH 2A-prime

International Nuclear Information System (INIS)

Raymond, J.C.; Hartmann, L.; Hartigan, P.

1988-01-01

An improved version of the bow shock theory previously applied to Herbig-Haro objects is presented. The modifications provide a more accurate calculation of the ionization state of material entering the bow shock. The revised preionization does not drastically affect the emission-line predictions for a 200 km/s bow shock model, though the effects will be more severe for slower shock velocities. The line profiles of the new models resemble the observed profiles somewhat more closely, and the relative emission-line intensities typically differ by 30 percent from those predicted by the older models. The models agree well with new IUE spectra and existing optical data for HH 2A-prime. 32 references

Investigation on Mie-Grüneisen type shock Hugoniot equation of state for concrete

Directory of Open Access Journals (Sweden)

M Katayama

2017-09-01

Full Text Available This paper ascertains that the bilinear shock Hugoniot equation of state (EOS can model the plasticizing process of the porous media like concrete material for high-velocity impact problems successfully. The negative slope of the bilinear Hugoniot for low particle velocity regime can simulate the process that the porosity of concrete may be compressed to form shock wave in concrete, through a series of numerical analyses over the investigation on the physical phenomena. The results of particle velocity for the concrete material are also discussed to be compared with those of non-porous aluminum alloy for 100 and 1000 m/s impact velocities. All the numerical simulations were carried out by applying the bilinear shock Hugoniot EOS to concrete which was linked to the binary object of a hydrocode: ANSYS Autodyn®[1−3] through a user’s subroutine.

FEMA Hazard Mitigation Assistance Flood Mitigation Assistance (FMA) Data

Data.gov (United States)

Department of Homeland Security — This dataset contains closed and obligated projects funded under the following Hazard Mitigation Assistance (HMA) grant programs: Flood Mitigation Assistance (FMA)....

Pressure measurements and an analytical model for laser-generated shock waves in solids at low irradiance

CERN Document Server

Romain, J P; Dayma, G; Boustie, M; Resseguier, T D; Combis, P

2002-01-01

Low amplitude shock waves (from 1 to 300 bar) have been generated in gold layers deposited on a quartz substrate, by laser pulses at an incident fluence from 0.4 to 4.0 J cm sup - sup 2. The quartz was used as a pressure gauge for recording the induced shock profile. At a fluence <1.4 J cm sup - sup 2 , the shock pressure does not exceed 10 bar and the shock front is followed by a tension peak typical of an absorption in solid state. An analytical model of the compression-tension process has been developed, accounting for shock pressure and shock profile evolution as a function of irradiation conditions and material properties. From this model a mechanical interpretation is given to previous observations of spalling of the irradiated target surface.

Pressure measurements and an analytical model for laser-generated shock waves in solids at low irradiance

Energy Technology Data Exchange (ETDEWEB)

Romain, J P [Laboratoire de Combustion et de Detonique, ENSMA, BP 40109, 86961 Futuroscope-Chasseneuil (France); Bonneau, F [Departement de Physique Theorique et Appliquee CEA/DAM Ile de France, BP 12, 91680 Bruyeres le Chatel (France); Dayma, G [Laboratoire de Combustion et de Detonique, ENSMA, BP 40109, 86961 Futuroscope-Chasseneuil (France); Boustie, M [Laboratoire de Combustion et de Detonique, ENSMA, BP 40109, 86961 Futuroscope-Chasseneuil (France); Resseguier, T de [Laboratoire de Combustion et de Detonique, ENSMA, BP 40109, 86961 Futuroscope-Chasseneuil (France); Combis, P [Departement de Physique Theorique et Appliquee CEA/DAM Ile de France, BP 12, 91680 Bruyeres le Chatel (France)

2002-11-11

Low amplitude shock waves (from 1 to 300 bar) have been generated in gold layers deposited on a quartz substrate, by laser pulses at an incident fluence from 0.4 to 4.0 J cm{sup -2}. The quartz was used as a pressure gauge for recording the induced shock profile. At a fluence <1.4 J cm{sup -2}, the shock pressure does not exceed 10 bar and the shock front is followed by a tension peak typical of an absorption in solid state. An analytical model of the compression-tension process has been developed, accounting for shock pressure and shock profile evolution as a function of irradiation conditions and material properties. From this model a mechanical interpretation is given to previous observations of spalling of the irradiated target surface.

Lightweight aluminum shock absorbers; Leichtbau-Stossdaempfer aus Aluminium

Energy Technology Data Exchange (ETDEWEB)

Kusche, R. [Serienentwicklung, ThyssenKrupp Bilstein GmbH, Ennepetal (Germany)

2004-12-01

One way in which the automotive industry is striving to reduce costs and environmental impact is by continuously lowering the fuel consumption of vehicles. To achieve this objective, lightweight materials are increasingly being used in automotive design. Increasing demands are also being made on shock absorber suppliers to reduce weight. (orig.)

Influence of recrystallization on thermal shock resistance of various tungsten grades

International Nuclear Information System (INIS)

Uytdenhouwen, I.; Decreton, M.; Hirai, T.; Linke, J.; Pintsuk, G.; Oost, G. van

2007-01-01

Thermal shock resistance of various tungsten grades (different manufacturing technologies and heat treatments) was examined under plasma disruption conditions, especially in the cracking regime, i.e. below the melting threshold. The tests have been simulated with the electron beam test facility JUDITH. The comparison of the thermal shock resistance showed that sintered tungsten appeared to be better than the deformed tungsten material and clear degradation after recrystallization was found. Damage processes linked to the mechanical properties of W are discussed

Wide range scaling laws for radiation driven shock speed, wall albedo and ablation parameters for high-Z materials

Science.gov (United States)

Mishra, Gaurav; Ghosh, Karabi; Ray, Aditi; Gupta, N. K.

2018-06-01

Radiation hydrodynamic (RHD) simulations for four different potential high-Z hohlraum materials, namely Tungsten (W), Gold (Au), Lead (Pb), and Uranium (U) are performed in order to investigate their performance with respect to x-ray absorption, re-emission and ablation properties, when irradiated by constant temperature drives. A universal functional form is derived for estimating time dependent wall albedo for high-Z materials. Among the high-Z materials studied, it is observed that for a fixed simulation time the albedo is maximum for Au below 250 eV, whereas it is maximum for U above 250 eV. New scaling laws for shock speed vs drive temperature, applicable over a wide temperature range of 100 eV to 500 eV, are proposed based on the physics of x-ray driven stationary ablation. The resulting scaling relation for a reference material Aluminium (Al), shows good agreement with that of Kauffman's power law for temperatures ranging from 100 eV to 275 eV. New scaling relations are also obtained for temperature dependent mass ablation rate and ablation pressure, through RHD simulation. Finally, our study reveals that for temperatures above 250 eV, U serves as a better hohlraum material since it offers maximum re-emission for x-rays along with comparable mass ablation rate. Nevertheless, traditional choice, Au works well for temperatures below 250 eV. Besides inertial confinement fusion (ICF), the new scaling relations may find its application in view-factor codes, which generally ignore atomic physics calculations of opacities and emissivities, details of laser-plasma interaction and hydrodynamic motions.

Multifidelity, multidisciplinary optimization of turbomachines with shock interaction

Science.gov (United States)

Joly, Michael Marie

Research on high-speed air-breathing propulsion aims at developing aircraft with antipodal range and space access. Before reaching high speed at high altitude, the flight vehicle needs to accelerate from takeoff to scramjet takeover. Air turbo rocket engines combine turbojet and rocket engine cycles to provide the necessary thrust in the so-called low-speed regime. Challenges related to turbomachinery components are multidisciplinary, since both the high compression ratio compressor and the powering high-pressure turbine operate in the transonic regime in compact environments with strong shock interactions. Besides, lightweight is vital to avoid hindering the scramjet operation. Recent progress in evolutionary computing provides aerospace engineers with robust and efficient optimization algorithms to address concurrent objectives. The present work investigates Multidisciplinary Design Optimization (MDO) of innovative transonic turbomachinery components. Inter-stage aerodynamic shock interaction in turbomachines are known to generate high-cycle fatigue on the rotor blades compromising their structural integrity. A soft-computing strategy is proposed to mitigate the vane downstream distortion, and shown to successfully attenuate the unsteady forcing on the rotor of a high-pressure turbine. Counter-rotation offers promising prospects to reduce the weight of the machine, with fewer stages and increased load per row. An integrated approach based on increasing level of fidelity and aero-structural coupling is then presented and allows achieving a highly loaded compact counter-rotating compressor.

On possible structures of normal ionizing shock waves in electromagnetic shock tubes

International Nuclear Information System (INIS)

Liberman, M.A.; Synakh, V.S.; Zakajdakhov, V.V.; Velikovich, A.L.

1982-01-01

The problem of possible structures of normal ionizing shock waves is studied. On the basis of the general theory of ionizing shock waves in magnetic fields, a similarity solution of the piston problem for an impenetrable piston and a magnetic piston is described and a numerical solution of the non-stationary piston problem is obtained. It is shown that precursor photo-ionization of the neutral gas by the radiation of the shock-heated gas is the dominant factor in shaping normal ionizing shock structures. In particular, it is shown that the strong overheating of atoms and ions in shock fronts is due to the tensor form of Ohm's law in the precursor region. (author)

Multiple spacecraft observations of interplanetary shocks: four spacecraft determination of shock normals

International Nuclear Information System (INIS)

Russell, C.T.; Mellott, M.M.; Smith, E.J.; King, J.H.

1983-01-01

ISEE 1,2,3 IMP8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for furture techniques. When the angle between upstream and downstream magnetic field is greater than 20, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, we recommend using overdetermined shock normal solutions whenever possible, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints

Heterogeneous free-surface profile of B4C polycrystal under shock compression

International Nuclear Information System (INIS)

Mashimo, T.; Uchino, M.

1997-01-01

Observations of the free-surface behavior under shock compression by the gapped-flat mirror method were performed on B 4 C and Si 3 N 4 ceramics to study their shock-yielding properties. Jagged profiles of the moving free-surface in the plastic region, with a special scale of about one mm and a maximum local displacement of a few 10s of μm, were observed for B 4 C polycrystals. Similar profiles for Si 3 N 4 polycrystals were smooth. Such profiles for B 4 C polycrystals were also observed in the elastic region. It is suggested that these observations reflect the heterogeneous nature of shock compression in solids, and further indicate that a macroscopic slip system plays an important role in the elastoplastic transition of B 4 C material under shock compression and decompression. copyright 1997 American Institute of Physics

Shock absorber

International Nuclear Information System (INIS)

Nemeth, J.D.

1981-01-01

A shock absorber for the support of piping and components in a nuclear power plant is described. It combines a high degree of stiffness under sudden shocks, e.g. seismic disturbances, with the ability to allow for thermal expansion without resistance when so required. (JIW)

Shock-wave compression of lithium niobate from 2.4 to 44 GPa

International Nuclear Information System (INIS)

Stanton, P.L.; Graham, R.A.

1979-01-01

Shock compression of lithium niobate above the Hugoniot elastic limit (about 2.5 GPa) reveals a succession of unusual features. Just above the Hugoniot elastic limit, the shock velocity is observed to be well below the bulk sound speed, indicative of a drastic reduction of shear strength. The shock velocity is observed to increase with particle velocity at an unusually large rate due to the reduction of strength in a very stiff material and an anomalously large pressure derivative of the bulk modulus. This later behavior may be due to the effects of localized shock heating resulting from heterogeneous shear deformation in ferroelectrics like lithium niobate and lithium tantalate in which increases in temperature are shown to have a strong effect on bulk modulus. A shock-induced polymorphic phase transition occurs at 13.9 GPa. Above the transition point the slope of the Hugoniot curve relating shock velocity and particle velocity is unusually low, indicative of a broad mixed phase region of undetermined extent. Limited work is reported on the isomorphous crystal, lithium tantalate, which exhibits features similar to lithium niobate with a Hugoniot elastic limit of 4 GPa and a phase transition in the vicinity of 19 GPa

49 CFR 178.358 - Specification 21PF fire and shock resistant, phenolic-foam insulated, metal overpack.

Science.gov (United States)

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Specification 21PF fire and shock resistant, phenolic-foam insulated, metal overpack. 178.358 Section 178.358 Transportation Other Regulations Relating... Class 7 (Radioactive) Materials § 178.358 Specification 21PF fire and shock resistant, phenolic-foam...

System Shock: The Archetype of Operational Shock

Science.gov (United States)

2017-05-25

the battle space. They can also facilitate a much greater understanding of the variables involved in each party’s decision - making process. However...system shock nests within current US Army Unified Land Operations doctrine. In order to test the utility of system shock theory to Gray Zone...23 Neil E. Harrison, “Thinking about the World We Make ” in Chaos Theory in the Social Sciences: Foundations and Applications

Experimental investigation of blast mitigation and particle-blast interaction during the explosive dispersal of particles and liquids

Science.gov (United States)

Pontalier, Q.; Loiseau, J.; Goroshin, S.; Frost, D. L.

2018-04-01

The attenuation of a blast wave from a high-explosive charge surrounded by a layer of inert material is investigated experimentally in a spherical geometry for a wide range of materials. The blast wave pressure is inferred from extracting the blast wave velocity with high-speed video as well as direct measurements with pressure transducers. The mitigant consists of either a packed bed of particles, a particle bed saturated with water, or a homogeneous liquid. The reduction in peak blast wave overpressure is primarily dependent on the mitigant to explosive mass ratio, M/C, with the mitigant material properties playing a secondary role. Relative peak pressure mitigation reduces with distance and for low values of M/C (pressure levels in the mid-to-far field. Solid particles are more effective at mitigating the blast overpressure than liquids, particularly in the near field and at low values of M/C, suggesting that the energy dissipation during compaction, deformation, and fracture of the powders plays an important role. The difference in scaled arrival time of the blast and material fronts increases with M/C and scaled distance, with solid particles giving the largest separation between the blast wave and cloud of particles. Surrounding a high-explosive charge with a layer of particles reduces the positive-phase blast impulse, whereas a liquid layer has no influence on the impulse in the far field. Taking the total impulse due to the blast wave and material impact into account implies that the damage to a nearby structure may actually be augmented for a range of distances. These results should be taken into consideration in the design of explosive mitigant systems.

Unlimited Relativistic Shock Surfing Acceleration

International Nuclear Information System (INIS)

Ucer, D.; Shapiro, V. D.

2001-01-01

Nonrelativistic shock surfing acceleration at quasiperpendicular shocks is usually considered to be a preacceleration mechanism for slow pickup ions to initiate diffusive shock acceleration. In shock surfing, the particle accelerates along the shock front under the action of the convective electric field of the plasma flow. However, the particle also gains kinetic energy normal to the shock and eventually escapes downstream. We consider the case when ions are accelerated to relativistic velocities. In this case, the ions are likely to be trapped for infinitely long times, because the energy of bounce oscillations tends to decrease during acceleration. This suggests the possibility of unlimited acceleration by shock surfing

Properties of a Laser Shock Wave in Al-Cu Alloy under Elevated Temperatures: A Molecular Dynamics Simulation Study

Directory of Open Access Journals (Sweden)

Xiankai Meng

2017-01-01

Full Text Available The laser shock wave (LSW generated by the interaction between a laser and a material has been widely used in laser manufacturing, such as laser shock peening and laser shock forming. However, due to the high strain rate, the propagation of LSW in materials, especially LSW at elevated temperatures, is difficult to study through experimental methods. A molecular dynamics simulation was used in this study to investigate the propagation of LSW in an Al-Cu alloy. The Hugoniot relations of LSW were obtained at different temperatures and the effects of elevated temperatures on shock velocity and shock pressure were analyzed. Then the elastic and plastic wave of the LSW was researched. Finally, the evolution of dislocations induced by LSW and its mechanism under elevated temperatures was explored. The results indicate that the shock velocity and shock pressure induced by LSW both decrease with the increasing temperatures. Moreover, the velocity of elastic wave and plastic wave both decrease with the increasing treatment temperature, while their difference decreases as the temperature increases. Moreover, the dislocation atoms increases with the increasing temperatures before 2 ps, while it decreases with the increasing temperatures after 2 ps. The reason for the results is related to the formation and evolution of extended dislocations.

Experimental investigation of blast mitigation and particle-blast interaction during the explosive dispersal of particles and liquids

Science.gov (United States)

Pontalier, Q.; Loiseau, J.; Goroshin, S.; Frost, D. L.

2018-05-01

The attenuation of a blast wave from a high-explosive charge surrounded by a layer of inert material is investigated experimentally in a spherical geometry for a wide range of materials. The blast wave pressure is inferred from extracting the blast wave velocity with high-speed video as well as direct measurements with pressure transducers. The mitigant consists of either a packed bed of particles, a particle bed saturated with water, or a homogeneous liquid. The reduction in peak blast wave overpressure is primarily dependent on the mitigant to explosive mass ratio, M/ C, with the mitigant material properties playing a secondary role. Relative peak pressure mitigation reduces with distance and for low values of M/ C (compaction, deformation, and fracture of the powders plays an important role. The difference in scaled arrival time of the blast and material fronts increases with M/ C and scaled distance, with solid particles giving the largest separation between the blast wave and cloud of particles. Surrounding a high-explosive charge with a layer of particles reduces the positive-phase blast impulse, whereas a liquid layer has no influence on the impulse in the far field. Taking the total impulse due to the blast wave and material impact into account implies that the damage to a nearby structure may actually be augmented for a range of distances. These results should be taken into consideration in the design of explosive mitigant systems.

Effects of response-shock interval and shock intensity on free-operant avoidance responding in the pigeon1

Science.gov (United States)

Klein, Marty; Rilling, Mark

1972-01-01

Two experiments investigated free-operant avoidance responding with pigeons using a treadle-pressing response. In Experiment I, pigeons were initially trained on a free-operant avoidance schedule with a response-shock interval of 32 sec and a shock-shock interval of 10 sec, and were subsequently exposed to 10 values of the response-shock parameter ranging from 2.5 to 150 sec. The functions relating response rate to response-shock interval were similar to the ones reported by Sidman in his 1953 studies employing rats, and were independent of the order of presentation of the response-shock values. Shock rates decreased as response-shock duration increased. In Experiment II, a free-operant avoidance schedule with a response-shock interval of 20 sec and a shock-shock interval of 5 sec was used, and shock intensities were varied over five values ranging from 2 to 32 mA. Response rates increased markedly as shock intensity increased from 2 to 8 mA, but rates changed little with further increases in shock intensity. Shock rates decreased as intensity increased from 2 to 8 mA, and showed little change as intensity increased from 8 to 32 mA. PMID:4652617

Diaphragmless shock wave generators for industrial applications of shock waves

Science.gov (United States)

Hariharan, M. S.; Janardhanraj, S.; Saravanan, S.; Jagadeesh, G.

2011-06-01

The prime focus of this study is to design a 50 mm internal diameter diaphragmless shock tube that can be used in an industrial facility for repeated loading of shock waves. The instantaneous rise in pressure and temperature of a medium can be used in a variety of industrial applications. We designed, fabricated and tested three different shock wave generators of which one system employs a highly elastic rubber membrane and the other systems use a fast acting pneumatic valve instead of conventional metal diaphragms. The valve opening speed is obtained with the help of a high speed camera. For shock generation systems with a pneumatic cylinder, it ranges from 0.325 to 1.15 m/s while it is around 8.3 m/s for the rubber membrane. Experiments are conducted using the three diaphragmless systems and the results obtained are analyzed carefully to obtain a relation between the opening speed of the valve and the amount of gas that is actually utilized in the generation of the shock wave for each system. The rubber membrane is not suitable for industrial applications because it needs to be replaced regularly and cannot withstand high driver pressures. The maximum shock Mach number obtained using the new diaphragmless system that uses the pneumatic valve is 2.125 ± 0.2%. This system shows much promise for automation in an industrial environment.

Longitudinal and Lateral Stress Measurements in NiTi under One-Dimensional Shock Loading

International Nuclear Information System (INIS)

Meziere, Y. J. E.; Millett, J. C. F.; Bourne, N. K.; Wallwork, A.; Workman, A.

2006-01-01

This paper investigates the influence of the impact stress on the magnitude of the shear stress under one-dimensional shock loading. The shear stress is calculated from the measured longitudinal and the lateral stresses. New data in terms of shock stress, particle velocity and shock velocity has been gathered. Results indicate that the lateral stress has a positive dependence on the impact stress. A general decrease of the lateral stress was also observed immediately after the impact, while the longitudinal stress remains constant for the duration of the pulse length. This suggests that the shear strength increases behind the shock front. This decrease had been found to reach a constant value for the specimens impacted at lower stress. A complex mechanism of deformation behind the shock front during loading was thus reveals. This limit, related to the inflexion point noted on the Hugoniot (Us-up), seems to be an effect of the martensitic phase transformation undergoes by the material

Applications of the fundamental solution for a thermal shock on a finite orthotropic cylindrical thin shell

International Nuclear Information System (INIS)

Woo, H.K.; Huang, C.L.D.

1979-01-01

The authors investigate the temperature variations in a thin cylindrical shell of graphite materials with finite length, subjected to an instantaneous thermal shock. The solutions for the line source and the area source of thermal shock are obtained. Quasi-linear theory for heat transfer is assumed. Grades ATJ and ZTA graphite are used in the numerical examples. As is expected, the orthotropically thermal properties significantly affect the temperature variations in the shell due to the thermal shocks. (Auth.)

Bio-inspired heterogeneous composites for broadband vibration mitigation.

Science.gov (United States)

Chen, Yanyu; Wang, Lifeng

2015-12-08

Structural biological materials have developed heterogeneous and hierarchical architectures that are responsible for the outstanding performance to provide protection against environmental threats including static and dynamic loading. Inspired by this observation, this research aims to develop new material and structural concepts for broadband vibration mitigation. The proposed composite materials possess a two-layered heterogeneous architecture where both layers consist of high-volume platelet-shape reinforcements and low-volume matrix, similar to the well-known "brick and mortar" microstructure of biological composites. Using finite element method, we numerically demonstrated that broadband wave attenuation zones can be achieved by tailoring the geometric features of the heterogeneous architecture. We reveal that the resulting broadband attenuation zones are gained by directly superimposing the attenuation zones in each constituent layer. This mechanism is further confirmed by the investigation into the phonon dispersion relation of each layer. Importantly, the broadband wave attenuation capability will be maintained when the mineral platelet orientation is locally manipulated, yet a contrast between the mineral platelet concentrations of the two constituent layers is essential. The findings of this work will provide new opportunities to design heterogeneous composites for broadband vibration mitigation and impact resistance under mechanically challenging environmental conditions.

Fluid dynamics of the shock wave reactor

Science.gov (United States)

Masse, Robert Kenneth

2000-10-01

High commercial incentives have driven conventional olefin production technologies to near their material limits, leaving the possibility of further efficiency improvements only in the development of entirely new techniques. One strategy known as the Shock Wave Reactor, which employs gas dynamic processes to circumvent limitations of conventional reactors, has been demonstrated effective at the University of Washington. Preheated hydrocarbon feedstock and a high enthalpy carrier gas (steam) are supersonically mixed at a temperature below that required for thermal cracking. Temperature recovery is then effected via shock recompression to initiate pyrolysis. The evolution to proof-of-concept and analysis of experiments employing ethane and propane feedstocks are presented. The Shock Wave Reactor's high enthalpy steam and ethane flows severely limit diagnostic capability in the proof-of-concept experiment. Thus, a preliminary blow down supersonic air tunnel of similar geometry has been constructed to investigate recompression stability and (especially) rapid supersonic mixing necessary for successful operation of the Shock Wave Reactor. The mixing capabilities of blade nozzle arrays are therefore studied in the air experiment and compared with analytical models. Mixing is visualized through Schlieren imaging and direct photography of condensation in carbon dioxide injection, and interpretation of visual data is supported by pressure measurement and flow sampling. The influence of convective Mach number is addressed. Additionally, thermal behavior of a blade nozzle array is analyzed for comparison to data obtained in the course of succeeding proof-of-concept experiments. Proof-of-concept is naturally succeeded by interest in industrial adaptation of the Shock Wave Reactor, particularly with regard to issues involving the scaling and refinement of the shock recompression. Hence, an additional, variable geometry air tunnel has been constructed to study the parameter

Holographic interferometric observation of shock wave focusing to extracorporeal shock wave lithotripsy

Science.gov (United States)

Takayama, Kazuyoshi; Obara, Tetsuro; Onodera, Osamu

1991-04-01

Underwater shock wave focusing is successfully applied to disintegrate and remove kidney stones or gallbladder stones without using surgical operations. This treatment is one of the most peaceful applications ofshock waves and is named as the Extracorporeal Shock Wave Lithotripsy. Ajoint research project is going on between the Institute ofFluid Science, Tohoku University and the School ofMedicine, Tohoku University. The paper describes a result of the fundamental research on the underwater shock wave focusing applied to the ESWL. Quantitatively to visualize the underwater shock waves, various optical flow visualization techniques were successfully used such as holographic interferometry, and shadowgraphs combined with Ima-Con high speed camera. Double exposure holographic interferometric observation revealed the mechanism of generation, propagation and focusing of underwater shock waves. The result of the present research was already used to manufacture a prototype machine and it has already been applied successfully to ESWL crinical treatments. However, despite of success in the clinical treatments, important fundamental questions still remain unsolved, i.e., effects of underwater shock wave focusing on tissue damage during the treatment. Model experiments were conducted to clarify mechanism of the tissue damage associated with the ESWL. Shock-bubble interactions were found responsible to the tissue damage during the ESWL treatment. In order to interprete experimental findings and to predict shock wave behavior and high pressures, a numerical simulation was carried. The numerical results agreed with the experiments.

Two-fluid dusty shocks: simple benchmarking problems and applications to protoplanetary discs

Science.gov (United States)

Lehmann, Andrew; Wardle, Mark

2018-05-01

The key role that dust plays in the interstellar medium has motivated the development of numerical codes designed to study the coupled evolution of dust and gas in systems such as turbulent molecular clouds and protoplanetary discs. Drift between dust and gas has proven to be important as well as numerically challenging. We provide simple benchmarking problems for dusty gas codes by numerically solving the two-fluid dust-gas equations for steady, plane-parallel shock waves. The two distinct shock solutions to these equations allow a numerical code to test different forms of drag between the two fluids, the strength of that drag and the dust to gas ratio. We also provide an astrophysical application of J-type dust-gas shocks to studying the structure of accretion shocks on to protoplanetary discs. We find that two-fluid effects are most important for grains larger than 1 μm, and that the peak dust temperature within an accretion shock provides a signature of the dust-to-gas ratio of the infalling material.

Ab Initio Studies of Shock-Induced Chemical Reactions of Inter-Metallics

Science.gov (United States)

Zaharieva, Roussislava; Hanagud, Sathya

2009-06-01

Shock-induced and shock assisted chemical reactions of intermetallic mixtures are studied by many researchers, using both experimental and theoretical techniques. The theoretical studies are primarily at continuum scales. The model frameworks include mixture theories and meso-scale models of grains of porous mixtures. The reaction models vary from equilibrium thermodynamic model to several non-equilibrium thermodynamic models. The shock-effects are primarily studied using appropriate conservation equations and numerical techniques to integrate the equations. All these models require material constants from experiments and estimates of transition states. Thus, the objective of this paper is to present studies based on ab initio techniques. The ab inito studies, to date, use ab inito molecular dynamics. This paper presents a study that uses shock pressures, and associated temperatures as starting variables. Then intermetallic mixtures are modeled as slabs. The required shock stresses are created by straining the lattice. Then, ab initio binding energy calculations are used to examine the stability of the reactions. Binding energies are obtained for different strain components super imposed on uniform compression and finite temperatures. Then, vibrational frequencies and nudge elastic band techniques are used to study reactivity and transition states. Examples include Ni and Al.

Laser-excited optical emission response of CdTe quantum dot/polymer nanocomposite under shock compression

Energy Technology Data Exchange (ETDEWEB)

Xiao, Pan [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Kang, Zhitao; Summers, Christopher J. [Phosphor Technology Center of Excellence, Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332-0826 (United States); Bansihev, Alexandr A.; Christensen, James M.; Dlott, Dana D. [School of Chemical Sciences and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Breidenich, Jennifer; Scripka, David A.; Thadhani, Naresh N. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Zhou, Min, E-mail: min.zhou@gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States)

2016-01-04

Laser-driven shock compression experiments and corresponding finite element method simulations are carried out to investigate the blueshift in the optical emission spectra under continuous laser excitation of a dilute composite consisting of 0.15% CdTe quantum dots by weight embedded in polyvinyl alcohol polymer. This material is a potential candidate for use as internal stress sensors. The analyses focus on the time histories of the wavelength blue-shift for shock loading with pressures up to 7.3 GPa. The combined measurements and calculations allow a relation between the wavelength blueshift and pressure for the loading conditions to be extracted. It is found that the blueshift first increases with pressure to a maximum and subsequently decreases with pressure. This trend is different from the monotonic increase of blueshift with pressure observed under conditions of quasistatic hydrostatic compression. Additionally, the blueshift in the shock experiments is much smaller than that in hydrostatic experiments at the same pressure levels. The differences in responses are attributed to the different stress states achieved in the shock and hydrostatic experiments and the time dependence of the mechanical response of the polymer in the composite. The findings offer a potential guide for the design and development of materials for internal stress sensors for shock conditions.

Shock Isolation Elements Testing for High Input Loadings. Volume III. Mechanical Shock Isolation Elements.

Science.gov (United States)

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*SPRINGS, (*SHOCK(MECHANICS), REDUCTION), TORSION BARS, ELASTOMERS, DAMPING, EQUATIONS OF MOTION, MODEL TESTS, TEST METHODS, NUCLEAR EXPLOSIONS, HARDENING.

Thermal shock problems in a plate

International Nuclear Information System (INIS)

Takeuti, Y.; Furukawa, T.

1981-01-01

The problems considered are coupled dynamic thermoelastic analysis in a plate. First we try to examine a problem of the coupled dynamic thermal stress problem with small time approximation for the finite region. Next, we treatise both effects individually by pursuing rigorous anaylsis without small time approximation. Finally we consider thermal shock problems in a plate against different values of heat transfer coefficient (Biot's number) for the time. In conclusion, for usual materials, the inertia effect may be disregarded in the pure thermal problems in contrast to the coupling effect which brings small lags in the temperature and thermal stress distributions. For the consideration of the maximum thermal stress problems, Manson's uncoupled quasi-static results give enough approximation to the thermal shock problems without significant error from our numerical results. The analysis is developed by the use of Laplace transforms and several useful graphical illustrations are given. (orig./HP)

PARTICLE ACCELERATION AT THE HELIOSPHERIC TERMINATION SHOCK WITH A STOCHASTIC SHOCK OBLIQUITY APPROACH

International Nuclear Information System (INIS)

Arthur, Aaron D.; Le Roux, Jakobus A.

2013-01-01

Observations by the plasma and magnetic field instruments on board the Voyager 2 spacecraft suggest that the termination shock is weak with a compression ratio of ∼2. However, this is contrary to the observations of accelerated particle spectra at the termination shock, where standard diffusive shock acceleration theory predicts a compression ratio closer to ∼2.9. Using our focused transport model, we investigate pickup proton acceleration at a stationary spherical termination shock with a moderately strong compression ratio of 2.8 to include both the subshock and precursor. We show that for the particle energies observed by the Voyager 2 Low Energy Charged Particle (LECP) instrument, pickup protons will have effective length scales of diffusion that are larger than the combined subshock and precursor termination shock structure observed. As a result, the particles will experience a total effective termination shock compression ratio that is larger than values inferred by the plasma and magnetic field instruments for the subshock and similar to the value predicted by diffusive shock acceleration theory. Furthermore, using a stochastically varying magnetic field angle, we are able to qualitatively reproduce the multiple power-law structure observed for the LECP spectra downstream of the termination shock

The Immunomodulatory Potential of tolDCs Loaded with Heat Shock Proteins

Directory of Open Access Journals (Sweden)

Willem van Eden

2017-11-01

Full Text Available Disease suppressive T cell regulation may depend on cognate interactions of regulatory T cells with self-antigens that are abundantly expressed in the inflamed tissues. Heat shock proteins (HSPs are by their nature upregulated in stressed cells and therefore abundantly present as potential targets for such regulation. HSP immunizations have led to inhibition of experimentally induced inflammatory conditions in various models. However, re-establishment of tolerance in the presence of an ongoing inflammatory process has remained challenging. Since tolerogenic DCs (tolDCs have the combined capacity of mitigating antigen-specific inflammatory responses and of endowing T cells with regulatory potential, it seems attractive to combine the anti-inflammatory qualities of tolDCs with those of HSPs.

Bright emissive core-shell spherical microparticles for shock compression spectroscopy

International Nuclear Information System (INIS)

Christensen, James M.; Banishev, Alexandr A.; Dlott, Dana D.

2014-01-01

Experiments were performed to study the response to shock compression of rhodamine 6G (R6G) dye encapsulated in 1.25 μm diameter silica microspheres. When R6G was encapsulated in microspheres, the emission intensity under steady-state irradiation (the brightness) was 3.4 times greater than the same dye in solution (the free dye). At least part of the brightness improvement was caused by an enhanced radiative rate. When the microspheres were embedded in poly-methylmethacrylate subjected to planar shocks in the 3–8.4 GPa range by laser-driven flyer plates, the dye emission redshifted and lost intensity. The dye emission redshift represents an instantaneous response to changes in the local density. In free dye samples, the shock-induced intensity loss had considerably slower rise times and fall times than the redshift. When dye was encapsulated in microspheres, the time dependence of the intensity loss matched the redshift almost exactly over a range of shock pressures and durations. The faster response to shock of dye in silica microspheres was explained by dye photophysics. The microsphere environment decreased the singlet state lifetime, which decreased the rise time, and it also decreased the triplet state lifetime, which decreased the fall time. Since it is much easier and more convenient to make measurements of intensity rather than spectral shift, these microspheres represent a substantial improvement in optical sensors to monitor shock compression of microstructured materials.

Measurement of the equation of state of porous materials through the use of shock waves generated by laser radiation; Mesure de l'equation d'etat de materiaux poreux a l'aide d'ondes de choc generees par laser

Energy Technology Data Exchange (ETDEWEB)

Philippe, F

2001-12-15

This work aims at measuring the equation of state of porous plastic materials in the view of their use in inertial confinement fusion. We have experimentally determined the shock polar curve of TMPTA (C{sub 15}H{sub 20}O{sub 6}) by the use of the impedance matching technique. This technique is based on the simultaneous measurement of the shock velocities in the 2 materials composing the target. The shock polar curve has been drawn for pressures ranging from 10 kbar to 3 Mbar and densities from 20 mg/cm{sup 3} to 1.1 g/cm{sup 3}. The use of a slit sweep camera to assess the propagation of the shock wave through the target has limited the accuracy of the technique to 10%. Experimental results match well data provided by the Sesame tables that are broadly used by hydrodynamic codes. Nevertheless the statistical distribution of experimental points seems to show a lower compressibility of the foam that might be attributed to a slight pre-heating process or to the effect of the foam micro-structure on the shock wave propagation. In order to improve the accuracy of the method, an attempt was made to use an active doppler interferometric diagnostic to measure shock wave velocities. It has been showed that the shock wave front in the foam is reflecting enough to make this method relevant if we can overcome the difficulty of a high luminous background. Despite that, we have succeeded in measuring with high accuracy, a point of the shock polar curve for 800 mg/cm{sup 3} dense TMPTA. (A.C.)

Primary system temperature limits and transient mitigation

Energy Technology Data Exchange (ETDEWEB)

Drucker, G.S.; Bost, D.S.

1978-10-03

Results of a study to determine the limiting temperature conditions in a large reactor system are presented. The study considers a sodium-cooled breeder reactor system having a loop-type primary system configuration. A temperature range of 930 to 1050/sup 0/F in reactor outlet temperature is covered. Significant findings were that the use of the materials for the 930/sup 0/F reference design, i.e., a core material of 20% cold-worked 316 stainless steel, a primary piping material of 316SS, and a steam generator material of unstabilized 2-1/4 Cr - 1 Mo resulted in limiting conditions in component performance at the higher temperatures. Means to circumvent these limits through the use of alternate materials, mitigation of thermal transients, and/or design changes are presented. The economic incentive to make some materials changes is also presented.

Ablative stabilization of Rayleigh-Taylor instabilities resulting from a laser-driven radiative shock

Science.gov (United States)

Huntington, C. M.; Shimony, A.; Trantham, M.; Kuranz, C. C.; Shvarts, D.; Di Stefano, C. A.; Doss, F. W.; Drake, R. P.; Flippo, K. A.; Kalantar, D. H.; Klein, S. R.; Kline, J. L.; MacLaren, S. A.; Malamud, G.; Miles, A. R.; Prisbrey, S. T.; Raman, K. S.; Remington, B. A.; Robey, H. F.; Wan, W. C.; Park, H.-S.

2018-05-01

The Rayleigh-Taylor (RT) instability is a common occurrence in nature, notably in astrophysical systems like supernovae, where it serves to mix the dense layers of the interior of an exploding star with the low-density stellar wind surrounding it, and in inertial confinement fusion experiments, where it mixes cooler materials with the central hot spot in an imploding capsule and stifles the desired nuclear reactions. In both of these examples, the radiative flux generated by strong shocks in the system may play a role in partially stabilizing RT instabilities. Here, we present experiments performed on the National Ignition Facility, designed to isolate and study the role of radiation and heat conduction from a shock front in the stabilization of hydrodynamic instabilities. By varying the laser power delivered to a shock-tube target with an embedded, unstable interface, the radiative fluxes generated at the shock front could be controlled. We observe decreased RT growth when the shock significantly heats the medium around it, in contrast to a system where the shock did not produce significant heating. Both systems are modeled with a modified set of buoyancy-drag equations accounting for ablative stabilization, and the experimental results are consistent with ablative stabilization when the shock is radiative. This result has important implications for our understanding of astrophysical radiative shocks and supernova radiative hydrodynamics [Kuranz et al., Nature Communications 9(1), 1564 (2018)].

Preferential acceleration in collisionless supernova shocks

International Nuclear Information System (INIS)

Hainebach, K.; Eichler, D.; Schramm, D.