Hypervelocity Impact Test Fragment Modeling: Modifications to the Fragment Rotation Analysis and Lightcurve Code

Science.gov (United States)

Gouge, Michael F.

2011-01-01

Hypervelocity impact tests on test satellites are performed by members of the orbital debris scientific community in order to understand and typify the on-orbit collision breakup process. By analysis of these test satellite fragments, the fragment size and mass distributions are derived and incorporated into various orbital debris models. These same fragments are currently being put to new use using emerging technologies. Digital models of these fragments are created using a laser scanner. A group of computer programs referred to as the Fragment Rotation Analysis and Lightcurve code uses these digital representations in a multitude of ways that describe, measure, and model on-orbit fragments and fragment behavior. The Dynamic Rotation subroutine generates all of the possible reflected intensities from a scanned fragment as if it were observed to rotate dynamically while in orbit about the Earth. This calls an additional subroutine that graphically displays the intensities and the resulting frequency of those intensities as a range of solar phase angles in a Probability Density Function plot. This document reports the additions and modifications to the subset of the Fragment Rotation Analysis and Lightcurve concerned with the Dynamic Rotation and Probability Density Function plotting subroutines.

Hypervelocity impact on Zr51Ti5Ni10Cu25Al9 bulk metallic glass

International Nuclear Information System (INIS)

Zheng, W.; Huang, Y.J.; Pang, B.J.; Shen, J.

2011-01-01

Highlights: → Hypervelocity impact experiments were performed on a bulk metallic glass. → Morphology of the bullet hole presents three different regions. → The post-impact samples keep glassy structure. → Mechanical properties of the post-impact samples were studied by nanoindentation. → Mechanical properties of the post-impact samples were discussed by free-volume model. - Abstract: In this study, the hypervelocity impact experiments were performed on Zr 51 Ti 5 Ni 10 Cu 25 Al 9 bulk metallic glass using a two-stage light gas gun. The morphologies of the bullet holes exhibit three different regions: melting area, vein-pattern area, and radiating core feature area, suggesting that various regions experience different stress states during the hypervelocity impact. For the post-impact samples, the nano-hardness increases and plastic deformability decreases both with the increase in the distance from the bullet hole and with the decrease in the impact velocity, which is discussed by means of spherical stress wave theory and free-volume model.

Axial focusing of energy from a hypervelocity impact on earth

International Nuclear Information System (INIS)

Boslough, M.B.; Chael, E.P.; Trucano, T.G.; Crawford, D.A.

1994-01-01

We have performed computational simulations to determine how energy from a large hypervelocity impact on the Earth's surface would couple to its interior. Because of the first-order axial symmetry of both the impact energy source and the stress-wave velocity structure of the Earth, a disproportionate amount of energy is dissipated along the axis defined by the impact point and its antipode (point opposite the impact). For a symmetric and homogeneous Earth model, all the impact energy that is radiated as seismic waves into the Earth at a given takeoff angle (ray parameter), independent of azimuthal direction, is refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Material on or near the axis of symmetry experiences more strain cycles with much greater amplitude than elsewhere, and therefore experiences more irreversible heating. The focusing is most intense in the upper mantle, within the asthenosphere, where seismic energy is most effectively converted to heat. For a sufficiently energetic impact, this mechanism might generate enough local heating to create an isostatic instability leading to uplift, possibly resulting in rifting, volcanism, or other rearrangement of the interior dynamics of the planet. These simulations demonstrate how hypervelocity impact energy can be transported to the Earth's interior, supporting the possibility of a causal link between large impacts on Earth and major internally-driven geophysical processes

Axial focusing of energy from a hypervelocity impact on earth

Energy Technology Data Exchange (ETDEWEB)

Boslough, M.B.; Chael, E.P.; Trucano, T.G.; Crawford, D.A.

1994-12-01

We have performed computational simulations to determine how energy from a large hypervelocity impact on the Earth`s surface would couple to its interior. Because of the first-order axial symmetry of both the impact energy source and the stress-wave velocity structure of the Earth, a disproportionate amount of energy is dissipated along the axis defined by the impact point and its antipode (point opposite the impact). For a symmetric and homogeneous Earth model, all the impact energy that is radiated as seismic waves into the Earth at a given takeoff angle (ray parameter), independent of azimuthal direction, is refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Material on or near the axis of symmetry experiences more strain cycles with much greater amplitude than elsewhere, and therefore experiences more irreversible heating. The focusing is most intense in the upper mantle, within the asthenosphere, where seismic energy is most effectively converted to heat. For a sufficiently energetic impact, this mechanism might generate enough local heating to create an isostatic instability leading to uplift, possibly resulting in rifting, volcanism, or other rearrangement of the interior dynamics of the planet. These simulations demonstrate how hypervelocity impact energy can be transported to the Earth`s interior, supporting the possibility of a causal link between large impacts on Earth and major internally-driven geophysical processes.

Analysis of simulated hypervelocity impacts on a titanium fuel tank from the Salyut 7 space station

Science.gov (United States)

Jantou, V.; McPhail, D. S.; Chater, R. J.; Kearsley, A.

2006-07-01

The aim of this project was to gain a better understanding of the microstructural effects of hypervelocity impacts (HVI) in titanium alloys. We investigated a titanium fuel tank recovered from the Russian Salyut 7 space station, which was launched on April 19, 1982 before being destroyed during an un-controlled re-entry in 1991, reportedly scattering debris over parts of South America. Several sections were cut out from the tank in order to undergo HVI simulations using a two-stage light gas gun. In addition, a Ti-6Al-4V alloy was studied for further comparison. The crater morphologies produced were successfully characterised using microscope-based white light interferometry (Zygo ® Corp, USA), while projectile remnants were identified via secondary ion mass spectrometry (SIMS). Microstructural alterations were investigated using focused ion beam (FIB) milling and depth profiling, as well as transmission electron microscopy (TEM). There was evidence of a very high density of dislocations in the vicinity of the crater. The extent of the deformation was localised in a region of about one to two radii of the impact craters. No notable differences were observed between the titanium alloys used during the hypervelocity impact tests.

Mass spectrometry of hyper-velocity impacts of organic micrograins.

Science.gov (United States)

Srama, Ralf; Woiwode, Wolfgang; Postberg, Frank; Armes, Steven P; Fujii, Syuji; Dupin, Damien; Ormond-Prout, Jonathan; Sternovsky, Zoltan; Kempf, Sascha; Moragas-Klostermeyer, Georg; Mocker, Anna; Grün, Eberhard

2009-12-01

The study of hyper-velocity impacts of micrometeoroids is important for the calibration of dust sensors in space applications. For this purpose, submicron-sized synthetic dust grains comprising either polystyrene or poly[bis(4-vinylthiophenyl)sulfide] were coated with an ultrathin overlayer of an electrically conductive organic polymer (either polypyrrole or polyaniline) and were accelerated to speeds between 3 and 35 km s(-1) using the Heidelberg Dust Accelerator facility. Time-of-flight mass spectrometry was applied to analyse the resulting ionic impact plasma using a newly developed Large Area Mass Analyser (LAMA). Depending on the projectile type and the impact speed, both aliphatic and aromatic molecular ions and cluster species were identified in the mass spectra with masses up to 400 u. Clusters resulting from the target material (silver) and mixed clusters of target and projectile species were also observed. Impact velocities of between 10 and 35 km s(-1) are suitable for a principal identification of organic materials in micrometeoroids, whereas impact speeds below approximately 10 km s(-1) allow for an even more detailed analysis. Molecular ions and fragments reflect components of the parent molecule, providing determination of even complex organic molecules embedded in a dust grain. In contrast to previous measurements with the Cosmic Dust Analyser instrument, the employed LAMA instrument has a seven times higher mass resolution--approximately 200--which allowed for a detailed analysis of the complex mass spectra. These fundamental studies are expected to enhance our understanding of cometary, interplanetary and interstellar dust grains, which travel at similar hyper-velocities and are known to contain both aliphatic and aromatic organic compounds. Copyright 2009 John Wiley & Sons, Ltd.

Asteroid deflection using a kinetic impactor: Insights from hypervelocity impact experiments

Science.gov (United States)

Hoerth, Tobias; Schäfer, Frank

2016-04-01

Within the framework of the planned AIDA mission [1], an impactor spacecraft (DART) hits the second component of the asteroid Didymos at hypervelocity. The impact crater will be observed from the AIM spacecraft and an observation of the ejecta plume is possible [1]. This allows conclusions to be drawn about the physical properties of the target material, and the momentum transfer will be studied [1]. In preparation for this mission, hypervelocity impact experiments can provide valuable information about the outcome of an impact event as a function of impactor and target material properties and, thus, support the interpretation of the data from the DART impact. In addition, these impact experiments provide an important means to validate numerical impact simulations required to simulate large-scale impacts that cannot be studied in laboratory experiments. Impact experiments have shown that crater morphology and size, crater growth and ejecta dynamics strongly depend on the physical properties of the target material [2]. For example, porous materials like sandstone lead to a shallower and slower ejection than low-porous materials like quartzite, and the cratering efficiency is reduced in porous targets leading to a smaller amount of ejected mass [3]. These phenomena result in a reduced momentum multiplication factor (often called "beta-value"), i.e. the ratio of the change in target momentum after the impact and the momentum of the projectile is smaller for porous materials. Hypervelocity impact experiments into target materials with different porosities and densities such as quartzite (2.9 %, 2.6 g/cm3), sandstone (25.3 %, 2 g/cm3), limestone (31 %, 1.8 g/cm3), and highly porous aerated concrete (87.5 %, 0.4 g/cm3) were conducted. Projectile velocities were varied between about 3 km/s and almost 7 km/s. A ballistic pendulum was used to measure the momentum transfer. The material strength required for scaling laws was determined for all target materials. The highest

Hypervelocity dust impact craters on photovoltaic devices imaged by ion beam induced charge

Energy Technology Data Exchange (ETDEWEB)

Yang, Changyi [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia); Wu, Yiyong; Lv, Gang [National Key Laboratory of Materials Behavior and Evaluation Technology in Space Environments, Harbin Institute of Technology, Harbin (China); Rubanov, Sergey [Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010 (Australia); Jamieson, David N., E-mail: d.jamieson@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia)

2015-04-01

Hypervelocity dust has a speed of greater than 5 km/s and is a significant problem for equipment deployed in space such as satellites because of impacts that damage vulnerable components. Photovoltaic (PV) arrays are especially vulnerable because of their large surface area and the performance can be degraded owing to the disruption of the structure of the junction in the cells making up the array. Satellite PV arrays returned to Earth after service in orbit reveal a large number of craters larger than 5 μm in diameter arising from hypervelocity dust impacts. Extensive prior work has been done on the analysis of the morphology of craters in PV cells to understand the origin of the micrometeoroid that caused the crater and to study the corresponding mechanical damage to the structure of the cell. Generally, about half the craters arise from natural micrometeoroids, about one third from artificial Al-rich debris, probably from solid rocket exhausts, and the remainder from miscellaneous sources both known and unknown. However to date there has not been a microscopic study of the degradation of the electrical characteristics of PV cells exposed to hypervelocity dust impacts. Here we present an ion beam induced charge (IBIC) pilot study by a 2 MeV He microbeam of craters induced on a Hamamatsu PIN diode exposed to artificial hypervelocity Al dust from a dust accelerator. Numerous 5–30 μm diameter craters were identified and the charge collection efficiency of the crater and surrounds mapped with IBIC with bias voltages between 0 and 20 V. At highest bias, it was found the efficiency of the crater had been degraded by about 20% compared to the surrounding material. The speed distribution achieved in the Al dust accelerator was peaked at about 4 km/s compared to 11–68 km/s for dust encountered in low Earth orbit. We are able to extrapolate the charge collection efficiency degradation rate of unbiased cells in space based on our current measurements and the

Hypervelocity dust impact craters on photovoltaic devices imaged by ion beam induced charge

International Nuclear Information System (INIS)

Yang, Changyi; Wu, Yiyong; Lv, Gang; Rubanov, Sergey; Jamieson, David N.

2015-01-01

Hypervelocity dust has a speed of greater than 5 km/s and is a significant problem for equipment deployed in space such as satellites because of impacts that damage vulnerable components. Photovoltaic (PV) arrays are especially vulnerable because of their large surface area and the performance can be degraded owing to the disruption of the structure of the junction in the cells making up the array. Satellite PV arrays returned to Earth after service in orbit reveal a large number of craters larger than 5 μm in diameter arising from hypervelocity dust impacts. Extensive prior work has been done on the analysis of the morphology of craters in PV cells to understand the origin of the micrometeoroid that caused the crater and to study the corresponding mechanical damage to the structure of the cell. Generally, about half the craters arise from natural micrometeoroids, about one third from artificial Al-rich debris, probably from solid rocket exhausts, and the remainder from miscellaneous sources both known and unknown. However to date there has not been a microscopic study of the degradation of the electrical characteristics of PV cells exposed to hypervelocity dust impacts. Here we present an ion beam induced charge (IBIC) pilot study by a 2 MeV He microbeam of craters induced on a Hamamatsu PIN diode exposed to artificial hypervelocity Al dust from a dust accelerator. Numerous 5–30 μm diameter craters were identified and the charge collection efficiency of the crater and surrounds mapped with IBIC with bias voltages between 0 and 20 V. At highest bias, it was found the efficiency of the crater had been degraded by about 20% compared to the surrounding material. The speed distribution achieved in the Al dust accelerator was peaked at about 4 km/s compared to 11–68 km/s for dust encountered in low Earth orbit. We are able to extrapolate the charge collection efficiency degradation rate of unbiased cells in space based on our current measurements and the

Ejection and Lofting of Dust from Hypervelocity Impacts on the Moon

Science.gov (United States)

Hermalyn, B.; Schultz, P. H.

2011-12-01

Hypervelocity impact events mobilize and redistribute fine-grained regolith dust across the surfaces of planetary bodies. The ejecta mass-velocity distribution controls the location and emplacement of these materials. The current flux of material falling on the moon is dominated by small bolides and should cause frequent impacts that eject dust at high speeds. For example, approximately 25 LCROSS-sized (~20-30m diameter) craters are statistically expected to be formed naturally on the moon during any given earth year. When scaled to lunar conditions, the high-speed component of ejecta from hypervelocity impacts can be lofted for significant periods of time (as evidenced by the LCROSS mission results, c.f., Schultz, et al., 2010, Colaprete, et al., 2010). Even at laboratory scales, ejecta can approach orbital velocities; the higher impact speeds and larger projectiles bombarding the lunar surface may permit a significant portion of material to be launched closer to escape velocity. When these ejecta return to the surface (or encounter local topography), they impact at hundreds of meters per second or faster, thereby "scouring" the surface with low mass oblique impacts. While these high-speed ejecta represent only a small fraction of the total ejected mass, the lofting and subsequent ballistic return of this dust has the highest mobilization potential and will be directly applicable to the upcoming LADEE mission. A suite of hypervelocity impact experiments into granular materials was performed at the NASA Ames Vertical Gun Range (AVGR). This study incorporates both canonical sand targets and air-fall pumice dust to simulate the mechanical properties of lunar regolith. The implementation of a Particle Tracking Velocimetry (PTV) technique permits non-intrusive measurement of the ejecta velocity distribution within the ejecta curtain by following the path of individual ejecta particles. The PTV system developed at the AVGR uses a series of high-speed cameras (ranging

Ultrahigh-speed X-ray imaging of hypervelocity projectiles

Science.gov (United States)

Miller, Stuart; Singh, Bipin; Cool, Steven; Entine, Gerald; Campbell, Larry; Bishel, Ron; Rushing, Rick; Nagarkar, Vivek V.

2011-08-01

High-speed X-ray imaging is an extremely important modality for healthcare, industrial, military and research applications such as medical computed tomography, non-destructive testing, imaging in-flight projectiles, characterizing exploding ordnance, and analyzing ballistic impacts. We report on the development of a modular, ultrahigh-speed, high-resolution digital X-ray imaging system with large active imaging area and microsecond time resolution, capable of acquiring at a rate of up to 150,000 frames per second. The system is based on a high-resolution, high-efficiency, and fast-decay scintillator screen optically coupled to an ultra-fast image-intensified CCD camera designed for ballistic impact studies and hypervelocity projectile imaging. A specially designed multi-anode, high-fluence X-ray source with 50 ns pulse duration provides a sequence of blur-free images of hypervelocity projectiles traveling at speeds exceeding 8 km/s (18,000 miles/h). This paper will discuss the design, performance, and high frame rate imaging capability of the system.

Theoretical model for plasma expansion generated by hypervelocity impact

International Nuclear Information System (INIS)

Ju, Yuanyuan; Zhang, Qingming; Zhang, Dongjiang; Long, Renrong; Chen, Li; Huang, Fenglei; Gong, Zizheng

2014-01-01

The hypervelocity impact experiments of spherical LY12 aluminum projectile diameter of 6.4 mm on LY12 aluminum target thickness of 23 mm have been conducted using a two-stage light gas gun. The impact velocity of the projectile is 5.2, 5.7, and 6.3 km/s, respectively. The experimental results show that the plasma phase transition appears under the current experiment conditions, and the plasma expansion consists of accumulation, equilibrium, and attenuation. The plasma characteristic parameters decrease as the plasma expands outward and are proportional with the third power of the impact velocity, i.e., (T e , n e ) ∝ v p 3 . Based on the experimental results, a theoretical model on the plasma expansion is developed and the theoretical results are consistent with the experimental data

Theoretical model for plasma expansion generated by hypervelocity impact

Energy Technology Data Exchange (ETDEWEB)

Ju, Yuanyuan; Zhang, Qingming, E-mail: qmzhang@bit.edu.cn; Zhang, Dongjiang; Long, Renrong; Chen, Li; Huang, Fenglei [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Gong, Zizheng [National Key Laboratory of Science and Technology on Reliability and Environment Engineering, Beijing Institute of Spacecraft Environment Engineering, Beijing 100094 (China)

2014-09-15

The hypervelocity impact experiments of spherical LY12 aluminum projectile diameter of 6.4 mm on LY12 aluminum target thickness of 23 mm have been conducted using a two-stage light gas gun. The impact velocity of the projectile is 5.2, 5.7, and 6.3 km/s, respectively. The experimental results show that the plasma phase transition appears under the current experiment conditions, and the plasma expansion consists of accumulation, equilibrium, and attenuation. The plasma characteristic parameters decrease as the plasma expands outward and are proportional with the third power of the impact velocity, i.e., (T{sub e}, n{sub e}) ∝ v{sub p}{sup 3}. Based on the experimental results, a theoretical model on the plasma expansion is developed and the theoretical results are consistent with the experimental data.

Multichannel fiber laser Doppler vibrometer studies of low momentum and hypervelocity impacts

Science.gov (United States)

Posada-Roman, Julio E.; Jackson, David A.; Cole, Mike J.; Garcia-Souto, Jose A.

2017-12-01

A multichannel optical fiber laser Doppler vibrometer was demonstrated with the capability of making simultaneous non-contact measurements of impacts at 3 different locations. Two sets of measurements were performed, firstly using small ball bearings (1 mm-5.5 mm) falling under gravity and secondly using small projectiles (1 mm) fired from an extremely high velocity light gas gun (LGG) with speeds in the range 1 km/s-8 km/s. Determination of impact damage is important for industries such as aerospace, military and rail, where the effect of an impact on the structure can result in a major structural damage. To our knowledge the research reported here demonstrates the first trials of a multichannel fiber laser Doppler vibrometer being used to detect hypervelocity impacts.

Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and micrometeoroids

International Nuclear Information System (INIS)

Katayama, Masahide; Takeba, Atsushi; Nitta, Kumi; Kawakita, Shirou; Matsumoto, Haruhisa; Kitazawa, Yukihito

2010-01-01

In order to establish the guidelines for the protection of unmanned spacecrafts from the space debris and micrometeoroid impacts, the experimental and numerical investigations have been conducted at Japan Aerospace Exploration Agency. This paper presents mainly its numerical methodology, especially from the viewpoint of highly non-linear and dynamic material model: i.e. the equation of state, constitutive model and fracture or failure model, including a brittle material model for ceramics and an equation of state for the shock-induced vaporization accompanied by hypervelocity impact. The experimental results of hypervelocity impact by two-stage light-gas gun and plasma drag gun are compared with corresponding numerical simulation results by using a hydrocode, and both results are demonstrated to be overall in good agreement with each other.

Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and micrometeoroids

Energy Technology Data Exchange (ETDEWEB)

Katayama, Masahide, E-mail: masahide.katayama@ctc-g.co.jp [Science and Engineering Systems Division, ITOCHU Techno-Solutions, 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo 100-6080 (Japan); Materials and Structures Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama-shi, Kanagawa 226-8503 (Japan); Takeba, Atsushi [Science and Engineering Systems Division, ITOCHU Techno-Solutions, 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo 100-6080 (Japan); Nitta, Kumi; Kawakita, Shirou; Matsumoto, Haruhisa [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba-city, Ibaraki 305-8505 (Japan); Kitazawa, Yukihito [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba-city, Ibaraki 305-8505 (Japan); Aero-Engine and Space Operations, IHI Corporation, 3-1-1, Toyosu, Koto-ku, Tokyo 135-8710 (Japan)

2010-10-15

In order to establish the guidelines for the protection of unmanned spacecrafts from the space debris and micrometeoroid impacts, the experimental and numerical investigations have been conducted at Japan Aerospace Exploration Agency. This paper presents mainly its numerical methodology, especially from the viewpoint of highly non-linear and dynamic material model: i.e. the equation of state, constitutive model and fracture or failure model, including a brittle material model for ceramics and an equation of state for the shock-induced vaporization accompanied by hypervelocity impact. The experimental results of hypervelocity impact by two-stage light-gas gun and plasma drag gun are compared with corresponding numerical simulation results by using a hydrocode, and both results are demonstrated to be overall in good agreement with each other.

Vulnerability analysis of a pressurized aluminum composite vessel against hypervelocity impacts

Directory of Open Access Journals (Sweden)

Hereil Pierre-Louis

2015-01-01

Full Text Available Vulnerability of high pressure vessels subjected to high velocity impact of space debris is analyzed with the response of pressurized vessels to hypervelocity impact of aluminum sphere. Investigated tanks are CFRP (carbon fiber reinforced plastics overwrapped Al vessels. Explored internal pressure of nitrogen ranges from 1 bar to 300 bar and impact velocity are around 4400 m/s. Data obtained from Xrays radiographies and particle velocity measurements show the evolution of debris cloud and shock wave propagation in pressurized nitrogen. Observation of recovered vessels leads to the damage pattern and to its evolution as a function of the internal pressure. It is shown that the rupture mode is not a bursting mode but rather a catastrophic damage of the external carbon composite part of the vessel.

Effect of impact angles on ejecta and crater shape of aluminum alloy 6061-T6 targets in hypervelocity impacts

Directory of Open Access Journals (Sweden)

Hayashi K.

2012-08-01

Full Text Available The effect of the impact angle of projectiles on the crater shape and ejecta in thick aluminum alloy targets was investigated in hypervelocity impacts. When polycarbonate projectiles and aluminum alloy 6061-T6 target were used, the impact angle of the projectiles clearly affected the crater shape, as expected. The impact angle also affected the ejecta mass, ejecta size and scatter angle. However, the effect at 15∘ and 22.5∘ was not great. When the impact angles were 30∘ and 45∘, the effect was clearly confirmed. The impact angle clearly affected the axial ratio of ejecta fragments, c/a.

Inertial fusion with hypervelocity impact

International Nuclear Information System (INIS)

Olariu, S.

1998-01-01

The physics of the compression and ignition processes in inertial fusion is to a certain extent independent of the nature of the incident energy pulse. The present strategy in the field of inertial fusion is to study several alternatives of deposition of the incident energy, and, at the same time, of conducting studies with the aid of available incident laser pulses. In a future reactor based on inertial fusion, the laser beams may be replaced by ion beams, which have a better energy efficiency. The main projects in the field of inertial fusion are the National Ignition Facility (NIF) in USA, Laser Megajoule (LMJ) in France, Gekko XII in Japan and Iskra V in Russia. NIF will be constructed at Lawrence Livermore National Laboratory, in California. LMJ will be constructed near Bordeaux. In the conventional approach to inertial confinement fusion, both the high-density fuel mass and the hot central spot are supposed to be produced by the deposition of the driver energy in the outer layers of the fuel capsule. Alternatively, the driver energy could be used only to produce the radial compression of the fuel capsule to high densities but relatively low temperatures, while the ignition of fusion reactions in the compressed capsule should be effected by a synchronized hypervelocity impact. Using this arrangement, it was supposed that a 54 μm projectile is incident with a velocity of 3 x 10 6 m s -1 upon a large-yield deuterium-tritium target at rest. The collision of the incident projectile and of the large-yield target takes place inside a high-Z cavity. A laser or heavy-ion pulse is converted at the walls of the cavity into X-rays, which compresses the incident projectile and the large-yield target in high-density states. The laser pulse and the movement of the incident projectile are synchronized such that the collision should take place when the densities are the largest. The collision converts the kinetic energy of the incident projectile into thermal energy, the

Testing of a Plasmadynamic Hypervelocity Dust Accelerator

Science.gov (United States)

Ticos, Catalin M.; Wang, Zhehui; Dorf, Leonid A.; Wurden, G. A.

2006-10-01

A plasmadynamic accelerator for microparticles (or dust grains) has been designed, built and tested at Los Alamos National laboratory. The dust grains are expected to be accelerated to hypervelocities on the order of 1-30 km/s, depending on their size. The key components of the plasmadynamic accelerator are a coaxial plasma gun operated at 10 kV, a dust dispenser activated by a piezoelectric transducer, and power and remote-control systems. The coaxial plasma gun produces a high density (10^18 cm-3) and low temperature (˜ 1 eV) plasma in deuterium ejected by J x B forces, which provides drag on the dust particles in its path. Carbon dust particles will be used, with diameters from 1 to 50 μm. The plasma parameters produced in the coaxial gun are presented and their implication to dust acceleration is discussed. High speed dust will be injected in the National Spherical Torus Experiment to measure the pitch angle of magnetic field lines.

Characterization of Orbital Debris via Hyper-Velocity Ground-Based Tests

Science.gov (United States)

Cowardin, Heather

2016-01-01

The purpose of the DebriSat project is to replicate a hyper-velocity fragmentation event using modern-day spacecraft materials and construction techniques to better improve the existing DoDand NASA breakup models.

Effects of Hypervelocity Impacts on Silicone Elastomer Seals and Mating Aluminum Surfaces

Science.gov (United States)

deGroh, Henry C., III; Steinetz, Bruce M.

2009-01-01

While in space silicone based elastomer seals planned for use on NASA's Crew Exploration Vehicle (CEV) are exposed to threats from micrometeoroids and orbital debris (MMOD). An understanding of these threats is required to assess risks to the crew, the CEV orbiter, and missions. An Earth based campaign of hypervelocity impacts on small scale seal rings has been done to help estimate MMOD threats to the primary docking seal being developed for the Low Impact Docking System (LIDS). LIDS is being developed to enable the CEV to dock to the ISS (International Space Station) or to Altair (NASA's next lunar lander). The silicone seal on LIDS seals against aluminum alloy flanges on ISS or Altair. Since the integrity of a seal depends on both sealing surfaces, aluminum targets were also impacted. The variables considered in this study included projectile mass, density, speed, incidence angle, seal materials, and target surface treatments and coatings. Most of the impacts used a velocity near 8 km/s and spherical aluminum projectiles (density = 2.7 g/cubic cm), however, a few tests were done near 5.6 km/s. Tests were also performed using projectile densities of 7.7, 2.79, 2.5 or 1.14 g/cubic cm. Projectile incidence angles examined included 0 deg, 45 deg, and 60 deg from normal to the plane of the target. Elastomer compounds impacted include Parker's S0383-70 and Esterline's ELA-SA-401 in the as received condition, or after an atomic oxygen treatment. Bare, anodized and nickel coated aluminum targets were tested simulating the candidate mating seal surface materials. After impact, seals and aluminum plates were leak tested: damaged seals were tested against an undamaged aluminum plate; and undamaged seals were placed at various locations over craters in aluminum plates. It has been shown that silicone elastomer seals can withstand an impressive level of damage before leaking beyond allowable limits. In general on the tests performed to date, the diameter of the crater in

Failure mechanism of monolayer graphene under hypervelocity impact of spherical projectile

Science.gov (United States)

Xia, Kang; Zhan, Haifei; Hu, De'An; Gu, Yuantong

2016-09-01

The excellent mechanical properties of graphene have enabled it as appealing candidate in the field of impact protection or protective shield. By considering a monolayer graphene membrane, in this work, we assessed its deformation mechanisms under hypervelocity impact (from 2 to 6 km/s), based on a serial of in silico studies. It is found that the cracks are formed preferentially in the zigzag directions which are consistent with that observed from tensile deformation. Specifically, the boundary condition is found to exert an obvious influence on the stress distribution and transmission during the impact process, which eventually influences the penetration energy and crack growth. For similar sample size, the circular shape graphene possesses the best impact resistance, followed by hexagonal graphene membrane. Moreover, it is found the failure shape of graphene membrane has a strong relationship with the initial kinetic energy of the projectile. The higher kinetic energy, the more number the cracks. This study provides a fundamental understanding of the deformation mechanisms of monolayer graphene under impact, which is crucial in order to facilitate their emerging future applications for impact protection, such as protective shield from orbital debris for spacecraft.

Characterization of Oribtal Debris via Hyper-Velocity Ground-Based Tests

Science.gov (United States)

Cowardin, H.

2015-01-01

Existing DoD and NASA satellite breakup models are based on a key laboratory-based test, Satellite Orbital debris Characterization Impact Test (SOCIT), which has supported many applications and matched on-orbit events involving older satellite designs reasonably well over the years. In order to update and improve the break-up models and the NASA Size Estimation Model (SEM) for events involving more modern satellite designs, the NASA Orbital Debris Program Office has worked in collaboration with the University of Florida to replicate a hypervelocity impact using a satellite built with modern-day spacecraft materials and construction techniques. The spacecraft, called DebriSat, was intended to be a representative of modern LEO satellites and all major designs decisions were reviewed and approved by subject matter experts at Aerospace Corporation. DebriSat is composed of 7 major subsystems including attitude determination and control system (ADCS), command and data handling (C&DH), electrical power system (EPS), payload, propulsion, telemetry tracking and command (TT&C), and thermal management. To reduce cost, most components are emulated based on existing design of flight hardware and fabricated with the same materials. All fragments down to 2 mm is size will be characterized via material, size, shape, bulk density, and the associated data will be stored in a database for multiple users to access. Laboratory radar and optical measurements will be performed on a subset of fragments to provide a better understanding of the data products from orbital debris acquired from ground-based radars and telescopes. The resulting data analysis from DebriSat will be used to update break-up models and develop the first optical SEM in conjunction with updates into the current NASA SEM. The characterization of the fragmentation will be discussed in the subsequent presentation.

Recent Representative IAT Studies in Hypervelocity Penetration Mechanics With Bibliographies

National Research Council Canada - National Science Library

Reinecke, W

2002-01-01

.... The IAT's investigations are experimental, analytical, and numerical and are concerned primarily with slender rods impacting armor steel and ceramic targets at hypervelocity that is, above about two km...

Plasma and collision processes of hypervelocity meteorite impact in the prehistory of life

Science.gov (United States)

Managadze, G.

2010-07-01

A new concept is proposed, according to which the plasma and collision processes accompanying hypervelocity impacts of meteorites can contribute to the arising of the conditions on early Earth, which are necessary for the appearance of primary forms of living matter. It was shown that the processes necessary for the emergence of living matter could have started in a plasma torch of meteorite impact and have continued in an impact crater in the case of the arising of the simplest life form. It is generally accepted that planets are the optimal place for the origin and evolution of life. In the process of forming the planetary systems the meteorites, space bodies feeding planet growth, appear around stars. In the process of Earth's formation, meteorite sizes ranged from hundreds and thousands of kilometres. These space bodies consisted mostly of the planetesimals and comet nucleus. During acceleration in Earth's gravitational field they reached hypervelocity and, hitting the surface of planet, generated powerful blowouts of hot plasma in the form of a torch. They also created giant-size craters and dense dust clouds. These bodies were composed of all elements needed for the synthesis of organic compounds, with the content of carbon being up to 5%-15%. A new idea of possible synthesis of the complex organic compounds in the hypervelocity impact-generated plasma torch was proposed and experimentally confirmed. A previously unknown and experimentally corroborated feature of the impact-generated plasma torch allowed a new concept of the prehistory of life to be developed. According to this concept the intensive synthesis of complex organic compounds arose during meteoritic bombardment in the first 0.5 billion years at the stage of the planet's formation. This most powerful and destructive action in Earth's history could have played a key role and prepared conditions for the origin of life. In the interstellar gas-dust clouds, the synthesis of simple organic matter could

Exploratory investigations of hypervelocity intact capture spectroscopy

Science.gov (United States)

Tsou, P.; Griffiths, D. J.

1993-01-01

The ability to capture hypervelocity projectiles intact opens a new technique available for hypervelocity research. A determination of the reactions taking place between the projectile and the capture medium during the process of intact capture is extremely important to an understanding of the intact capture phenomenon, to improving the capture technique, and to developing a theory describing the phenomenon. The intact capture of hypervelocity projectiles by underdense media generates spectra, characteristic of the material species of projectile and capture medium involved. Initial exploratory results into real-time characterization of hypervelocity intact capture techniques by spectroscopy include ultra-violet and visible spectra obtained by use of reflecting gratings, transmitting gratings, and prisms, and recorded by photographic and electronic means. Spectrometry proved to be a valuable real-time diagnostic tool for hypervelocity intact capture events, offering understanding of the interactions of the projectile and the capture medium during the initial period and providing information not obtainable by other characterizations. Preliminary results and analyses of spectra produced by the intact capture of hypervelocity aluminum spheres in polyethylene (PE), polystyrene (PS), and polyurethane (PU) foams are presented. Included are tentative emission species identifications, as well as gray body temperatures produced in the intact capture process.

The electromagnetic properties of plasma produced by hypervelocity impact

Science.gov (United States)

Zhang, Qingming; Gong, Liangfei; Ma, Yuefen; Long, Renrong; Gong, Zizheng

2018-02-01

The change of electron density in moving plasma in this paper is empirically determined according to multiple ground-based experimental results and the assumption of the Maxwell distribution. Moreover, the equation of the magnetic field intensity, dominated by the current due to the collective electron movement during the expansion, is presented on the basis of the Biot-Savart law, and its relationship with time and space is subsequently depicted. In addition, hypervelocity impact experiments on a 2AL12 target have been carried out using a two-stage light gas gun to accelerate a 2AL12 projectile of 6.4 mm to 6.2 km/s. Spiral coils are designed to measure the intensity of the electromagnetic field induced by this impact. The experimental results show that the magnetic field strength is an alternate pulse maintaining nearly 1 ms and its maximum is close to 15 μT, which is strong enough to interfere with the communication circuit and chip in spacecrafts. Lastly, numerical simulation of the magnetic field intensity using this experimental parameter reveals that the intensity in our estimation from our theory tends to be well consistent with the experimental data in the first peak of the pulse signal.

Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

Science.gov (United States)

Ryan, S.; Ordonez, E.; Christiansen, E. L.; Lear, D. M.

2010-01-01

Open cell metallic foam core sandwich panel structures are of interest for application in spacecraft micrometeoroid and orbital debris shields due to their novel form and advantageous structural and thermal performance. Repeated shocking as a result of secondary impacts upon individual foam ligaments during the penetration process acts to raise the thermal state of impacting projectiles ; resulting in fragmentation, melting, and vaporization at lower velocities than with traditional shielding configurations (e.g. Whipple shield). In order to characterize the protective capability of these structures, an extensive experimental campaign was performed by the Johnson Space Center Hypervelocity Impact Technology Facility, the results of which are reported in this paper. Although not capable of competing against the protection levels achievable with leading heavy shields in use on modern high-risk vehicles (i.e. International Space Station modules), metallic foam core sandwich panels are shown to provide a substantial improvement over comparable structural panels and traditional low weight shielding alternatives such as honeycomb sandwich panels and metallic Whipple shields. A ballistic limit equation, generalized in terms of panel geometry, is derived and presented in a form suitable for application in risk assessment codes.

Elemental analyses of hypervelocity microparticle impact sites on Interplanetary Dust Experiment sensor surfaces

Science.gov (United States)

Simon, Charles G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. A.; Wortman, Jim J.; Brownlee, D. E.

1993-01-01

The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity microparticles (approximately 0.2 to approximately 100 micron diameter) that struck the active sensors with enough energy to break down the 0.4 or 1.0 micron thick SIO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. The high purity Al-SiO2-Si substrates allowed detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) was used to create two-dimensional elemental ion intensity maps of microparticle impact sites on the IDE sensors. The element intensities in the central craters of the impacts were corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results were used to classify the particles' origins as 'manmade,' 'natural,' or 'indeterminate.' The last classification resulted from the presence of too little impactor residue, analytical interference from high background contamination, the lack of information on silicon and aluminum residues, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters of these features. Thus far a total of 79 randomly selected microparticle impact sites from the six primary sides of the LDEF have been analyzed: 36 from tray C-9 (Leading (ram), or East, side), 18 from tray C-3

First Principles Based Reactive Atomistic Simulations to Understand the Effects of Molecular Hypervelocity Impact on Cassini's Ion and Neutral Mass Spectrometer

Science.gov (United States)

Jaramillo-Botero, A.; Cheng, M-J; Cvicek, V.; Beegle, Luther W.; Hodyss, R.; Goddard, W. A., III

2011-01-01

We report here on the predicted impact of species such as ice-water, CO2, CH4, and NH3, on oxidized titanium, as well as HC species on diamond surfaces. These simulations provide the dynamics of product distributions during and after a hypervelocity impact event, ionization fractions, and dissociation probabilities for the various species of interest as a function of impact velocity (energy). We are using these results to determine the relevance of the fragmentation process to Cassini INMS results, and to quantify its effects on the observed spectra.

The intact capture of hypervelocity dust particles using underdense foams

Science.gov (United States)

Maag, Carl R.; Borg, J.; Tanner, William G.; Stevenson, T. J.; Bibring, J.-P.

1994-01-01

probability of survival for the impacting particle. The primary objectives of the experiment are to (1) Examine the morphology of primary and secondary hypervelocity impact craters. Primary attention will be paid to craters caused by ejecta during hypervelocity impacts of different substrates. (2) Determine the size distribution of ejecta by means of witness plates and collect fragments of ejecta from craters by means of momentum-sensitive mcropore foam. (3) Assess the directionality of the flux by means of penetration-hole alignment of thin films placed above the cells. (4) Capture intact the particles that perforated the thin film and entered the cell. Capture media consisted of both previously flight-tested micropore foams and aerogel. The foams had different latent heats of fusion and, accordingly, will capture particles over a range of momenta. Aerogel was incorporated into the cells to determine the minimum diameter than can be captured intact.

A meteorite crater on Earth formed on September 15, 2007: The Carancas hypervelocity impact

Science.gov (United States)

Tancredi, G.; Ishitsuka, J.; Schultz, P. H.; Harris, R. S.; Brown, P.; Revelle, D. O.; Antier, K.; Le Pichon, A.; Rosales, D.; Vidal, E.; Varela, M. E.; Sánchez, L.; Benavente, S.; Bojorquez, J.; Cabezas, D.; Dalmau, A.

2009-01-01

On September 15, 2007, a bright fireball was observed and a big explosion was heard by many inhabitants near the southern shore of Lake Titicaca. In the community of Carancas (Peru), a 13.5 m crater and several fragments of a stony meteorite were found close to the site of the impact. The Carancas event is the first impact crater whose formation was directly observed by several witnesses as well as the first unambiguous seismic recording of a crater-forming meteorite impact on Earth. We present several lines of evidence that suggest that the Carancas crater was a hypervelocity impact. An event like this should have not occurred according to the accepted picture of stony meteoroids ablating in the Earth’s atmosphere, therefore it challenges our present models of entry dynamics. We discuss alternatives to explain this particular event. This emphasizes the weakness in the pervasive use of “average” parameters (such as tensile strength, fragmentation behavior and ablation behavior) in current modeling efforts. This underscores the need to examine a full range of possible values for these parameters when drawing general conclusions from models about impact processes.

Electromagnetic Effices from Impacts on Spacecraft

Science.gov (United States)

Close, Sigrid

2018-04-01

Hypervelocity micro particles, including meteoroids and space debris with masses electromagnetic pulse (EMP) with a broad frequency spectrum. Subsequent plasma oscillations resulting from instabilities can also emit significant power and may be responsible for many reported satellite anomalies. We present theory and recent results from ground-based impact tests aimed at characterizing hypervelocity impact plasma and show that impact-produced radio frequency (RF) emissions occurred in frequencies ranging from VHF through L-band and that these emissions were highly correlated with fast (> 20 km/s) impacts that produced a fully ionized plasma.

Two-dimensional computer simulation of hypervelocity impact cratering: some preliminary results for Meteor Crater, Arizona

Energy Technology Data Exchange (ETDEWEB)

Bryan, J.B.; Burton, D.E.; Cunningham, M.E.; Lettis, L.A. Jr.

1978-06-01

A computational approach used for subsurface explosion cratering was extended to hypervelocity impact cratering. Meteor (Barringer) Crater, Arizona, was selected for the first computer simulation because it is one of the most thoroughly studied craters. It is also an excellent example of a simple, bowl-shaped crater and is one of the youngest terrestrial impact craters. Initial conditions for this calculation included a meteorite impact velocity of 15 km/s, meteorite mass of 1.67 x 10/sup 8/ kg, with a corresponding kinetic energy of 1.88 x 10/sup 16/ J (4.5 megatons). A two-dimensional Eulerian finite difference code called SOIL was used for this simulation of a cylindrical iron projectile impacting at normal incidence into a limestone target. For this initial calculation, a Tillotson equation-of-state description for iron and limestone was used with no shear strength. Results obtained for this preliminary calculation of the formation of Meteor Crater are in good agreement with field measurements. A color movie based on this calculation was produced using computer-generated graphics. 19 figures, 5 tables, 63 references.

Two-dimensional computer simulation of hypervelocity impact cratering: some preliminary results for Meteor Crater, Arizona

International Nuclear Information System (INIS)

Bryan, J.B.; Burton, D.E.; Cunningham, M.E.; Lettis, L.A. Jr.

1978-06-01

A computational approach used for subsurface explosion cratering was extended to hypervelocity impact cratering. Meteor (Barringer) Crater, Arizona, was selected for the first computer simulation because it is one of the most thoroughly studied craters. It is also an excellent example of a simple, bowl-shaped crater and is one of the youngest terrestrial impact craters. Initial conditions for this calculation included a meteorite impact velocity of 15 km/s, meteorite mass of 1.67 x 10 8 kg, with a corresponding kinetic energy of 1.88 x 10 16 J (4.5 megatons). A two-dimensional Eulerian finite difference code called SOIL was used for this simulation of a cylindrical iron projectile impacting at normal incidence into a limestone target. For this initial calculation, a Tillotson equation-of-state description for iron and limestone was used with no shear strength. Results obtained for this preliminary calculation of the formation of Meteor Crater are in good agreement with field measurements. A color movie based on this calculation was produced using computer-generated graphics. 19 figures, 5 tables, 63 references

Two-dimensional computer simulation of hypervelocity impact cratering: some preliminary results for Meteor Crater, Arizona

International Nuclear Information System (INIS)

Bryan, J.B.; Burton, D.E.; Cunningham, M.E.; Lettis, L.A. Jr.

1978-04-01

A computational approach used for subsurface explosion cratering has been extended to hypervelocity impact cratering. Meteor (Barringer) Crater, Arizona, was selected for our first computer simulation because it was the most thoroughly studied. It is also an excellent example of a simple, bowl-shaped crater and is one of the youngest terrestrial impact craters. Shoemaker estimates that the impact occurred about 20,000 to 30,000 years ago [Roddy (1977)]. Initial conditions for this calculation included a meteorite impact velocity of 15 km/s. meteorite mass of 1.57E + 08 kg, with a corresponding kinetic energy of 1.88E + 16 J (4.5 megatons). A two-dimensional Eulerian finite difference code called SOIL was used for this simulation of a cylindrical iron projectile impacting at normal incidence into a limestone target. For this initial calculation a Tillotson equation-of-state description for iron and limestone was used with no shear strength. A color movie based on this calculation was produced using computer-generated graphics. Results obtained for this preliminary calculation of the formation of Meteor Crater, Arizona, are in good agreement with Meteor Crater Measurements

Hydrocode modeling of the spallation process during hypervelocity impacts: Implications for the ejection of Martian meteorites

Science.gov (United States)

Kurosawa, Kosuke; Okamoto, Takaya; Genda, Hidenori

2018-02-01

Hypervelocity ejection of material by impact spallation is considered a plausible mechanism for material exchange between two planetary bodies. We have modeled the spallation process during vertical impacts over a range of impact velocities from 6 to 21 km/s using both grid- and particle-based hydrocode models. The Tillotson equations of state, which are able to treat the nonlinear dependence of density on pressure and thermal pressure in strongly shocked matter, were used to study the hydrodynamic-thermodynamic response after impacts. The effects of material strength and gravitational acceleration were not considered. A two-dimensional time-dependent pressure field within a 1.5-fold projectile radius from the impact point was investigated in cylindrical coordinates to address the generation of spalled material. A resolution test was also performed to reject ejected materials with peak pressures that were too low due to artificial viscosity. The relationship between ejection velocity veject and peak pressure Ppeak was also derived. Our approach shows that "late-stage acceleration" in an ejecta curtain occurs due to the compressible nature of the ejecta, resulting in an ejection velocity that can be higher than the ideal maximum of the resultant particle velocity after passage of a shock wave. We also calculate the ejecta mass that can escape from a planet like Mars (i.e., veject > 5 km/s) that matches the petrographic constraints from Martian meteorites, and which occurs when Ppeak = 30-50 GPa. Although the mass of such ejecta is limited to 0.1-1 wt% of the projectile mass in vertical impacts, this is sufficient for spallation to have been a plausible mechanism for the ejection of Martian meteorites. Finally, we propose that impact spallation is a plausible mechanism for the generation of tektites.

Hypervelocity Expansion Facility for Fundamental High-Enthalpy Research

Science.gov (United States)

2017-02-27

ii Final Technical Report of Contract ONR N00014-15-1-2260 Entitled: HYPERVELOCITY EXPANSION FACILITY FOR FUNDAMENTAL HIGH-ENTHALPY...previous DoD investments in high-energy pulsed laser diagnostics for instantaneous planar velocimetry and thermometry to perform scientific studies of...capability for fundamental and applied studies of hypervelocity high enthalpy flows. In this document, we report on the progress over the 18-month

Influence of different gaps among the split targets with gradient potential to the discharge effects generated by hypervelocity impact

Science.gov (United States)

Tang, Enling; Zhao, Liangliang; Han, Yafei; Zhang, Qingming; Wang, Ruizhi; He, Liping; Liu, Shuhua

2018-04-01

Due to the actual situation of spacecraft surface' charging, such as convex corners, weld line, whalebone and a multiple-interfaces with different materials, all these are main factors leading to uneven charging of spacecraft surface, even creating gradient potential. If the charging spacecraft surface is impacted by debris or micrometeor, discharge effect induced by impacting will pose a serious threat to spacecraft in orbit. So realizing spacecraft charging surface with different potential differences and grasping discharge characteristics are a decisive importance at the different experimental conditions in laboratory. To simulate the spacecraft surface with a gradient potential in laboratory, spacecraft surface is split into different parts, which different gaps reserved in 2 adjacent surface is added resistance to create different potential surfaces, and the high potential surface as a impact target in the split targets. Charging circuit system realizing different gradient potential and discharge test system are built by ourselves, combining with two-stage light gas gun loading system, six sets of experiments have been performed about hypervelocity impact on 2A12 aluminum split targets with gradient potentials. In the experiments, gaps of 2A12 aluminum target are the same among different parts in every experiments, the gaps of the split targets are 2mm, 3mm, 5mm, 7mm and 10mm in the experiments, respectively. And the applied voltage is 300V in all the experiments and high-potential 2A12 aluminum plate as the impact target. The experiments have been performed at the impact velocity of about 3km/s and the incidence angles of 60o and 90o (between projectile flying trajectory and target plane), respectively. Voltage probe and current probes are used for acquiring discharge voltages and currents during the process of the impact. The experimental results showed that the discharge induced by impact plasma were generated among high and low-potential target by forming

Influence of different gaps among the split targets with gradient potential to the discharge effects generated by hypervelocity impact

Directory of Open Access Journals (Sweden)

Enling Tang

2018-04-01

Full Text Available Due to the actual situation of spacecraft surface’ charging, such as convex corners, weld line, whalebone and a multiple-interfaces with different materials, all these are main factors leading to uneven charging of spacecraft surface, even creating gradient potential. If the charging spacecraft surface is impacted by debris or micrometeor, discharge effect induced by impacting will pose a serious threat to spacecraft in orbit. So realizing spacecraft charging surface with different potential differences and grasping discharge characteristics are a decisive importance at the different experimental conditions in laboratory. To simulate the spacecraft surface with a gradient potential in laboratory, spacecraft surface is split into different parts, which different gaps reserved in 2 adjacent surface is added resistance to create different potential surfaces, and the high potential surface as a impact target in the split targets. Charging circuit system realizing different gradient potential and discharge test system are built by ourselves, combining with two-stage light gas gun loading system, six sets of experiments have been performed about hypervelocity impact on 2A12 aluminum split targets with gradient potentials. In the experiments, gaps of 2A12 aluminum target are the same among different parts in every experiments, the gaps of the split targets are 2mm, 3mm, 5mm, 7mm and 10mm in the experiments, respectively. And the applied voltage is 300V in all the experiments and high-potential 2A12 aluminum plate as the impact target. The experiments have been performed at the impact velocity of about 3km/s and the incidence angles of 60o and 90o (between projectile flying trajectory and target plane, respectively. Voltage probe and current probes are used for acquiring discharge voltages and currents during the process of the impact. The experimental results showed that the discharge induced by impact plasma were generated among high and low

Hypervelocity Launching and Frozen Fuels as a Major Contribution to Spaceflight

Science.gov (United States)

Cocks, F. H.; Harman, C. M.; Klenk, P. A.; Simmons, W. N.

Acting as a virtual first stage, a hypervelocity launch together with the use of frozen hydrogen/frozen oxygen propellant, offers a Single-Stage-To-Orbit (SSTO) system that promises an enormous increase in SSTO mass-ratio. Ram acceleration provides hypervelocity (2 km/sec) to the orbital vehicle with a gas gun supplying the initial velocity required for ram operation. The vehicle itself acts as the center body of a ramjet inside a launch tube, filled with gaseous fuel and oxidizer, acting as an engine cowling. The high acceleration needed to achieve hypervelocity precludes a crew, and it would require greatly increased liquid fuel tank structural mass if a liquid propellant is used for post-launch vehicle propulsion. Solid propellants do not require as much fuel- chamber strengthening to withstand a hypervelocity launch as do liquid propellants, but traditional solid fuels have lower exhaust velocities than liquid hydrogen/liquid oxygen. The shock-stability of frozen hydrogen/frozen oxygen propellant has been experimentally demonstrated. A hypervelocity launch system using frozen hydrogen/frozen oxygen propellant would be a revolutionary new development in spaceflight.

Excess of L-Alanine in Amino Acids Synthesized in a Plasma Torch Generated by a Hypervelocity Meteorite Impact Reproduced in the Laboratory

Science.gov (United States)

Managadze, George G.; Engle, Michael H.; Getty, Stephanie A.; Wurz, Peter; Brinckerhoff, William B.; Shokolov, Anatoly; Sholin, Gennady; Terent'ev, Sergey A.; Chumikov, Alexander E.; Skalkin, Alexander S

2016-01-01

We present a laboratory reproduction of hypervelocity impacts of a carbon containing meteorite on a mineral substance representative of planetary surfaces. The physical conditions of the resulting impact plasma torch provide favorable conditions for abiogenic synthesis of protein amino acids: We identified glycine and alanine, and in smaller quantities serine, in the produced material. Moreover, we observe breaking of alanine mirror symmetry with L excess, which coincides with the bioorganic world. Therefore the selection of L-amino acids for the formation of proteins for living matter could have been the result from plasma processes occurring during the impact meteorites on the surface. This indicates that the plasma torch from meteorite impacts could play an important role in the formation of biomolecular homochirality. Thus, meteorite impacts possibly were the initial stage of this process and promoted conditions for the emergence of a living matter.

Hypervelocity impact of concrete

International Nuclear Information System (INIS)

Watson, A.J.; Anderson, W.F.; Archer, B.

1982-01-01

Blocks of concrete and various other materials were impacted by high speed copper jets at the centre of one face, the resulting transient phenomena were measured using ultra high speed photography and various electrical signal transducers. Measurements were made of the jet velocity, penetration rate, crack velocity and initiation time, and strain pulse propagation. Post test measurements were made using electron microscopy, ultra sonics and stereoscopic photography. (orig.) [de

Secondary ion mass spectrometry (SIMS) analysis of hypervelocity microparticle impact sites on LDEF surfaces

Science.gov (United States)

Simon, C. G.; Buonaquisti, A. J.; Batchelor, D. A.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. R.; Wortman, J. J.; Brownlee, D. E.; Best, S. R.

1995-01-01

Two dimensional elemental ion maps have been recorded for hundreds of microparticle impact sites and contamination features on LDEF surfaces. Since the majority of the analyzed surfaces were metal-oxide-silicon (MOS) impact detectors from the Interplanetary Dust Experiment, a series of 'standard' and 'blank' analyses of these surfaces are included. Hypervelocity impacts of forsterite olivine microparticles on activated flight sensors served as standards while stylus and pulsed laser simulated 'impacts' served as analytical blanks. Results showed that despite serious contamination issues, impactor residues can be identified in greater than 1/3 of the impact sites. While aluminum oxide particles could not be detected on aluminum surfaces, they were detected on germanium surfaces from row 12. Remnants of manmade debris impactors consisting of paint chips and bits of metal were identified on surfaces from LDEF Rows 3 (west or trailing side), 6 (south), 9 (ram or leading side), 12 (north) and the space end. Higher than expected ratios of manmade microparticle impacts to total microparticle impacts were found on the space end and the trailing side. These results were consistent with time-tagged and time-segregated microparticle impact data from the IDE and other LDEF experiments. A myriad of contamination interferences were identified and their effects on impactor debris identification mitigated during the course of this study. These interferences include pre-, post and inflight deposited surface contaminants as well as indigenous heterogeneous material contaminants. Non-flight contaminations traced to human origins, including spittle and skin oils, contributed significant levels of alkali-rich carbonaceous interferences. A ubiquitous layer of in-flight deposited silicaceous contamination varied in thickness with location on LDEF, even on a micro scale. In-flight deposited (low velocity) contaminants include urine droplets and bits of metal film from eroded thermal

Development of a Thermo-chemical Non-equilibrium Solver for Hypervelocity Flows

Science.gov (United States)

Balasubramanian, R.; Anandhanarayanan, K.

2015-04-01

In the present study, a three dimensional flowsolver is indigenously developed to numerically simulate hypervelocity thermal and chemical non equilibrium reactive air flow past flight vehicles. The two-temperature, five species, seventeen reactions, thermo-chemical non equilibrium, non-ionizing, air-chemistry model of Park is implemented in a compressible viscous code CERANS and solved in the finite volume framework. The energy relaxation is addressed by a conservation equation for the vibrational energy of the gas mixture resulting in the evaluation of its vibrational temperature. The AUSM-PW+ numerical flux function has been used for modeling the convective fluxes and a central differencing approximation is used for modeling the diffusive fluxes. The flowsolver had been validated for specifically chosen test cases with inherent flow complexities of non-ionizing hypervelocity thermochemical nonequilibrium flows and results obtained are in good agreement with results available in open literature.

Marshall Space Flight Center's Impact Testing Facility Capabilities

Science.gov (United States)

Finchum, Andy; Hubbs, Whitney; Evans, Steve

2008-01-01

Marshall Space Flight Center s (MSFC) Impact Testing Facility (ITF) serves as an important installation for space and missile related materials science research. The ITF was established and began its research in spacecraft debris shielding in the early 1960s, then played a major role in the International Space Station debris shield development. As NASA became more interested in launch debris and in-flight impact concerns, the ITF grew to include research in a variety of impact genres. Collaborative partnerships with the DoD led to a wider range of impact capabilities being relocated to MSFC as a result of the closure of Particle Impact Facilities in Santa Barbara, California. The Particle Impact Facility had a 30 year history in providing evaluations of aerospace materials and components during flights through rain, ice, and solid particle environments at subsonic through hypersonic velocities. The facility s unique capabilities were deemed a "National Asset" by the DoD. The ITF now has capabilities including environmental, ballistic, and hypervelocity impact testing utilizing an array of air, powder, and two-stage light gas guns to accommodate a variety of projectile and target types and sizes. Numerous upgrades including new instrumentation, triggering circuitry, high speed photography, and optimized sabot designs have been implemented. Other recent research has included rain drop demise characterization tests to obtain data for inclusion in on-going model development. The current and proposed ITF capabilities range from rain to micrometeoroids allowing the widest test parameter range possible for materials investigations in support of space, atmospheric, and ground environments. These test capabilities including hydrometeor, single/multi-particle, ballistic gas guns, exploding wire gun, and light gas guns combined with Smooth Particle Hydrodynamics Code (SPHC) simulations represent the widest range of impact test capabilities in the country.

Production of Prebiotic Molecule Precursors from Hypervelocity Impact Simulation Experiments on Carbonate Sediments

Science.gov (United States)

Farcy, B. J.; Grubisic, A.; Li, X.; Pinnick, V. T.; Sutton, M.; Pavlov, A.; Brinckerhoff, W. B.

2017-12-01

Organic molecules, including amino acids and other biotic precursors, have been shown to form in the cooling and expanding plasma plume generated from hypervelocity impacts through the processes of atomization, ionization, and molecular recombination of impactor and impact surface. Various sources of carbon, such as atmospheric methane and carbonaceous material from meteorites, are known to yield cyano-bearing molecules and simple amino acids from impact plasmas. However, the role of mineralogical carbon has not yet been investigated in this process. We have performed experiments using laser ablation mass spectrometry (LA-MS) to study the negative ion yield of plasma-produced prebiotic molecules. A mixture of 10% NH4Cl and 90% CaCO3 was pressed into a pellet and ablated with a 1064 nm Nd:YAG laser, and the resultant negative ions were measured by a plasma analyzer quadrupole MS. Mass spectra show characteristic peaks at m/z = 26 and m/z = 42, indicating the presence of CN- and CNO- ions. When isotopically labeled 15NH4Cl and Ca13CO3 were used in the sample ablation pellet, the purported CN- and CNO- peaks shifted according to their added isotopic mass. Indeed, comparison of resulting ion formation from momentum-based techniques, such as massive cluster secondary ion mass spectrometry, show comparable fragmentation and recombination of CN- and CNO- ions. These findings show that CN- ions, as well as CN radicals and thus HCN, can be formed during meteoritic bombardment of carbonate minerals. During the late heavy bombardment of the earth from 4.1-3.8 Ga, impact-driven chemistry could have played a dominant role in shaping the earth's early prebiotic inventory and sources of chemical energy. As carbonate sediments are common in the Archean, carbonate deposits are most likely an important contributor of carbon for this process, along with atmospheric and meteoritic carbon sources.

Simple light gas guns for hypervelocity studies

International Nuclear Information System (INIS)

Combs, S.K.; Haselton, H.H.; Milora, S.L.

1990-01-01

Two-stage light guns are used extensively in hypervelocity research. The applications of this technology include impact studies and special materials development. Oak Ridge National Laboratory (ORNL) has developed two-stage guns that accelerate small projectiles (4-mm nominal diameter) to velocities of up to ∼5 km/s. These guns are relatively small and simple (thus, easy to operate), allowing a significant number of test shots to be carried out and data accumulated in a short time. Materials that have been used for projectiles include plastics, frozen isotopes of hydrogen, and lithium hydride. One gun has been used to demonstrate repetitive operation at a rate of 0.7 Hz; and, with a few design improvements, it appears capable of performing at firing frequencies of 1--2 Hz. A schematic of ORNL two-stage device is shown below. Unlike most such devices, no rupture disks are used. Instead, a fast valve (high-flow type) initiates the acceleration process in the first stage. Projectiles can be loaded into the gun breech via the slide mechanism; this action has been automated which allows repetitive firing. Alternatively, the device is equipped with ''pipe gun'' apparatus in which gas can be frozen in situ in the gun barrel to form the projectile. This equipment operates with high reliability and is well suited for small-scale testing at high velocity. 17 refs., 6 figs., 2 tabs

Numerical investigations on pressurized AL-composite vessel response to hypervelocity impacts: Comparison between experimental works and a numerical code

Directory of Open Access Journals (Sweden)

Mespoulet Jérôme

2015-01-01

Full Text Available Response of pressurized composite-Al vessels to hypervelocity impact of aluminum spheres have been numerically investigated to evaluate the influence of initial pressure on the vulnerability of these vessels. Investigated tanks are carbon-fiber overwrapped prestressed Al vessels. Explored internal air pressure ranges from 1 bar to 300 bar and impact velocity are around 4400 m/s. Data obtained from experiments (Xray radiographies, particle velocity measurement and post-mortem vessels have been compared to numerical results given from LS-DYNA ALE-Lagrange-SPH full coupling models. Simulations exhibit an under estimation in term of debris cloud evolution and shock wave propagation in pressurized air but main modes of damage/rupture on the vessels given by simulations are coherent with post-mortem recovered vessels from experiments. First results of this numerical work are promising and further simulation investigations with additional experimental data will be done to increase the reliability of the simulation model. The final aim of this crossed work is to numerically explore a wide range of impact conditions (impact angle, projectile weight, impact velocity, initial pressure that cannot be explore experimentally. Those whole results will define a rule of thumbs for the definition of a vulnerability analytical model for a given pressurized vessel.

Hybrid Guidance Control for a Hypervelocity Small Size Asteroid Interceptor Vehicle

Science.gov (United States)

Zebenay, Melak M.; Lyzhoft, Joshua R.; Barbee, Brent W.

2017-01-01

Near-Earth Objects (NEOs) are comets and/or asteroids that have orbits in proximity with Earth's own orbit. NEOs have collided with the Earth in the past, which can be seen at such places as Chicxulub crater, Barringer crater, and Manson crater, and will continue in the future with potentially significant and devastating results. Fortunately such NEO collisions with Earth are infrequent, but can happen at any time. Therefore it is necessary to develop and validate techniques as well as technologies necessary to prevent them. One approach to mitigate future NEO impacts is the concept of high-speed interceptor. This concept is to alter the NEO's trajectory via momentum exchange by using kinetic impactors as well as nuclear penetration devices. The interceptor has to hit a target NEO at relative velocity which imparts a sufficient change in NEO velocity. NASA's Deep Impact mission has demonstrated this scenario by intercepting Comet Temple 1, 5 km in diameter, with an impact relative speed of approximately 10 km/s. This paper focuses on the development of hybrid guidance navigation and control (GNC) algorithms for precision hypervelocity intercept of small sized NEOs. The spacecraft's hypervelocity and the NEO's small size are critical challenges for a successful mission as the NEO will not fill the field of view until a few seconds before intercept. The investigation needs to consider the error sources modeled in the navigation simulation such as spacecraft initial state uncertainties in position and velocity. Furthermore, the paper presents three selected spacecraft guidance algorithms for asteroid intercept and rendezvous missions. The selected algorithms are classical Proportional Navigation (PN) based guidance that use a first order difference to compute the derivatives, Three Plane Proportional Navigation (TPPN), and the Kinematic Impulse (KI). A manipulated Bennu orbit that has been changed to impact Earth will be used as a demonstrative example to compare the

Development and application of streakline visualization in hypervelocity flows

Energy Technology Data Exchange (ETDEWEB)

Lemieux, P.; Hornung, H.G. [Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, CA 91125 (United States)

2002-07-01

A method for visualizing streaklines in hypervelocity flows has been developed. The method uses the high temperatures produced in hypervelocity flows to ablate small amounts of sodium deposited onto a wire stretched across the flow and to broaden the lines in the sodium spectrum. By using a dye laser, tuned to a wavelength close to one of the sodium D-lines, as the light source in shadowgraph or Schlieren visualization, streaklines seeded with sodium become visible through absorption and/or enhanced refractivity. The technique has been used to investigate the stability of the shear layer produced by the curved bow shock on a cylindrically blunted wedge. The results suggest that the shear layer is unstable, exhibiting structures with a wavelength that is comparable to half the nose radius of the body. (orig.)

Final Results of Shuttle MMOD Impact Database

Science.gov (United States)

Hyde, J. L.; Christiansen, E. L.; Lear, D. M.

2015-01-01

The Shuttle Hypervelocity Impact Database documents damage features on each Orbiter thought to be from micrometeoroids (MM) or orbital debris (OD). Data is divided into tables for crew module windows, payload bay door radiators and thermal protection systems along with other miscellaneous regions. The combined number of records in the database is nearly 3000. Each database record provides impact feature dimensions, location on the vehicle and relevant mission information. Additional detail on the type and size of particle that produced the damage site is provided when sampling data and definitive spectroscopic analysis results are available. Guidelines are described which were used in determining whether impact damage is from micrometeoroid or orbital debris impact based on the findings from scanning electron microscopy chemical analysis. Relationships assumed when converting from observed feature sizes in different shuttle materials to particle sizes will be presented. A small number of significant impacts on the windows, radiators and wing leading edge will be highlighted and discussed in detail, including the hypervelocity impact testing performed to estimate particle sizes that produced the damage.

Micrometeoroid impact simulations using a railgun electromagnetic accelerator

International Nuclear Information System (INIS)

Upshaw, J.L.; Kajs, J.P.

1991-01-01

The Center for Electromechanics at The University of Texas at Austin (CEM-UT), using a railgun electromagnetic (EM) accelerator, has done a series of hypervelocity micrometeoroid impact simulations. Simulations done to date (78 tests) were carried out under contracts with Lockheed Palo Alto Research Laboratory and Martin Marietta Corporation. The tests were designed to demonstrate that railguns can provide a repeatable means of accelerating particles between 10 -4 and 10 -7 g to hypervelocities within a high-vacuum flight chamber. Sodalime glass beads were accelerated up to 11 km/s impacting into silicon, aluminum, quartz and various proprietary targets. At the muzzle of the gun was a 5.8-m-long, high-vacuum flight chamber. Targets were placed in this chamber at various distances from the gun. Impact craters on all the targets were examined using a light-source microscope and several targets were further examined using a scanning electron microscope. Gun and flight range diagnostics, along with experimental setups and results for several of the experiments, are presented in this paper

DebriSat Hypervelocity Impact Test

Science.gov (United States)

2015-08-01

public release; distribution unlimited.  Targets: Scaled Multishock Shield, DebrisLV, and DebriSat  500-600 g hollow aluminum and nylon projectile... insulation . DebriSat’s internal components were structurally similar to real flight hardware but were nonfunctional. AEDC-TR-15-S-2 6...structures with an AL 5052 honeycomb core and M55J carbon fiber face sheets. The basic system characteristics of the DebriSat are given in Table 1

Determination of parameters for hypervelocity dust grains encountered in near-Earth space

Science.gov (United States)

Tanner, William G.; Maag, Carl R.; Alexander, W. Merle; Sappenfield, Patricia

1993-01-01

Primarily interest was in the determination of the population of micrometeoroids and space debris and interpretation of the hole size in a thin film or in a micropore foam returned from space with theoretical calculations describing the event. In order to augment the significance of the theoretical calculations of the impact event, an experiment designed to analyze the charge production due to hypervelocity impacts on thin films also produced data which described the penetration properties of micron and sub-micron sized projectiles. The thin film penetration sites in the 500 A and 1000 A aluminum films were counted and a size distribution function was derived. In the case of the very smallest dust grains, there were no independent measurements of velocities like that which existed for the larger dust grains (d(sub p) is less than or equal to 1 micron). The primary task then became to assess the relationship between the penetration hole and the particle diameter of the projectile which made the hole. The most promising means to assess the measure of the diameters of impacting grains came in the form of comparing cratering mechanics to penetration mechanics. Future experimentation will produce measurements of the cratering as opposed to the penetrating event. Particles encountered by surfaces while being flown in space will degrade that surface in a systematic manner even when the impact is with small hypervelocity particles, d(sub p) is less than or equal to 10 microns. Though not to a degree which would precipitate a catastrophic failure of a system, the degradation of the materials comprising the interconnected system will occur. It is the degradation of the optical system and the subsequent embrittlement of other materials that can lead to degradation if not to failure. It is to this end that research was conducted to compare the primary consequences for experiments which will be flown to those which have been returned.

HYPERFUSE: a hypervelocity inertial confinement system for fusion energy production and fission waste transmutation

International Nuclear Information System (INIS)

Makowitz, H.; Powell, J.R.; Wiswall, R.

1980-01-01

Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from an LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., 137 Cs, 90 Sr, 129 I, 99 Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,α), (n,γ), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R=1.0 to 3.0) requirements

IADC Vulnerability Report, IT32-13

Science.gov (United States)

Christiansen, E. L.; Miller, J. E.; Hyde, Jimx

2016-01-01

This section provides hypervelocity impact test data for two types of batteries: Lithium-Ion (Li-Ion) and Nickel Hydrogen (Ni-H2) batteries. The impact tests were directed by the NASA Johnson Space Center Hypervelocity Impact Technology (HVIT) group in Houston Texas, and were performed at the NASA White Sands Test Facility (WSTF).

DebriSat - A Planned Laboratory-Based Satellite Impact Experiment for Breakup Fragment Characterization

Science.gov (United States)

Liou, J.-C.; Fitz-Coy, N.; Werremeyer, M.; Huynh, T.; Voelker, M.; Opiela, J.

2012-01-01

DebriSat is a planned laboratory ]based satellite hypervelocity impact experiment. The goal of the project is to characterize the orbital debris that would be generated by a hypervelocity collision involving a modern satellite in low Earth orbit (LEO). The DebriSat project will update and expand upon the information obtained in the 1992 Satellite Orbital Debris Characterization Impact Test (SOCIT), which characterized the breakup of a 1960 's US Navy Transit satellite. There are three phases to this project: the design and fabrication of an engineering model representing a modern, 50-cm/50-kg class LEO satellite known as DebriSat; conduction of a laboratory-based hypervelocity impact to catastrophically break up the satellite; and characterization of the properties of breakup fragments down to 2 mm in size. The data obtained, including fragment size, area ]to ]mass ratio, density, shape, material composition, optical properties, and radar cross ]section distributions, will be used to supplement the DoD fs and NASA fs satellite breakup models to better describe the breakup outcome of a modern satellite. Updated breakup models will improve mission planning, environmental models, and event response. The DebriSat project is sponsored by the Air Force fs Space and Missile Systems Center and the NASA Orbital Debris Program Office. The design and fabrication of DebriSat is led by University of Florida with subject matter experts f support from The Aerospace Corporation. The major milestones of the project include the complete fabrication of DebriSat by September 2013, the hypervelocity impact of DebriSat at the Air Force fs Arnold Engineering Development Complex in early 2014, and fragment characterization and data analyses in late 2014.

In-Flight Imaging Systems for Hypervelocity and Re-Entry Vehicles, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — It is proposed to create a rugged, reliable, compact, standardized imaging system for hypervelocity and re-entry vehicles using sapphire windows, small imagers, and...

Characterizing Hypervelocity Impact (HVI-Induced Pitting Damage Using Active Guided Ultrasonic Waves: From Linear to Nonlinear

Directory of Open Access Journals (Sweden)

Menglong Liu

2017-05-01

Full Text Available Hypervelocity impact (HVI, ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting damage is introduced. The pitting damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of damage (multitudinous damage within a singular inspection region, a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation are extracted, for detecting gross damage whose characteristic dimensions are comparable to the wavelength of the probing wave; nonlinear-wise, changes in the signal features in the frequency domain (e.g., second harmonic generation, which are proven to be more sensitive than their linear counterparts to small-scale damage, are explored to characterize HVI-induced pitting damage scattered in the inner layer. A numerical simulation, supplemented with experimental validation, quantitatively reveals the accumulation of nonlinearity of the guided waves when the waves traverse the pitting damage, based on which linear and nonlinear damage indices are proposed. A path-based rapid imaging algorithm, in conjunction with the use of the developed linear and nonlinear indices, is developed, whereby the HVI-induced pitting damage is characterized in images in terms of the probability of occurrence.

Hypervelocity Dust Injection for Plasma Diagnostic Applications

Science.gov (United States)

Ticos, Catalin

2005-10-01

Hypervelocity micron-size dust grain injection was proposed for high-temperature magnetized plasma diagnosis. Multiple dust grains are launched simultaneously into high temperature plasmas at several km/s or more. The hypervelocity dust grains are ablated by the electron and ion fluxes. Fast imaging of the resulting luminous plumes attached to each grain is expected to yield local magnetic field vectors. Combination of multiple local magnetic field vectors reproduces 2D or even 3D maps of the internal magnetic field topology. Key features of HDI are: (1) a high spatial resolution, due to a relatively small transverse size of the elongated tail, and (2) a small perturbation level, as the dust grains introduce negligible number of particles compared to the plasma particle inventory. The latter advantage, however, could be seriously compromised if the gas load from the accelerator has an unobstructed access to the diagnosed plasma. Construction of a HDI diagnostic for National Spherical Torus Experiment (NSTX), which includes a coaxial plasma gun for dust grain acceleration, is underway. Hydrogen and deuterium gas discharges inside accelerator are created by a ˜ 1 mF capacitor bank pre-charged up to 10 kV. The diagnostic apparatus also comprises a dust dispenser for pre-loading the accelerator with dust grains, and an imaging system that has a high spatial and temporal resolution.

Distributed energy store powered railguns for hypervelocity launch

Science.gov (United States)

Maas, Brian L.; Bauer, David P.; Marshall, Richard A.

1993-01-01

Highly distributed power supplies are proposed as a basis for current difficulties with hypervelocity railgun power-supply compactness. This distributed power supply configuration reduces rail-to-rail voltage behind the main armature, thereby reducing the tendency for secondary armature current formation; secondary current elimination is essential for achieving the efficiencies associated with muzzle velocity above 6 km/sec. Attention is given to analytical and experimental results for two distributed energy storage schemes.

Development of a Numerical Model of Hypervelocity Impact into a Pressurized Composite Overwrapped Pressure Vessel

Science.gov (United States)

Garcia, M. A.; Davis, B. A.; Miller, J. E.

2017-01-01

considered a catastrophic failure. This assumption is conservative and made due to lack of knowledge on the level of allow-able damage to the composite overwrap that can be sustained and still allow successful completion of the mission. To quantify the allowable damage level to the composite overwrap involves assessing stress redistribution following damage as well as evaluating possible time-dependent mechanisms involved in the COPV response to an impact event. Limited published work in this subject has shown that COPV can withstand at least some level of damage due to high energy impacts. These observations have been confirmed and expanded upon in recent experimental research performed by NASA. This research has demonstrated that there is not only robustness in a COPV to compensate for CFRP damage, but has also identified two significant failure modes for pressurized COPV. The lowest threshold failure mode involves the perforation of the vessel, and the highest threshold failure mode is the catastrophic rupture. While both of these failure modes mean a loss of the COPV, system robustness affords some tolerance to the venting as opposed to the more catastrophic rupture. As a consequence, it is necessary to understand the conditions that result in the transition between these failure modes. The aforementioned experimental research has been performed in both the unpressurized and pressurized condition to identify the damage level that triggered the failure thresh-old. This COPV test program was sponsored by the NASA Engineering and Safety Center (NESC), and tests were performed at NASA White Sands Test Facility (WSTF). Planning and coordination were provided by NASA JSC Hypervelocity Impact Technology (HVIT) group, and the COPVs were provided by the ISS Program. Unpressurized testing has been conducted at the pressure of the vacuum test chamber, while, the pressurized testing has been conducted at 290 +/- 10 bar (4,200 ? 100 psi) using nitrogen as the pressurizing gas, which

Laboratory Impact Experiments

Science.gov (United States)

Horanyi, M.; Munsat, T.

2017-12-01

The experimental and theoretical programs at the SSERVI Institute for Modeling Plasmas, Atmospheres, and Cosmic Dust (IMPACT) address the effects of hypervelocity dust impacts and the nature of the space environment of granular surfaces interacting with solar wind plasma and ultraviolet radiation. These are recognized as fundamental planetary processes due their role in shaping the surfaces of airless planetary objects, their plasma environments, maintaining dust haloes, and sustaining surface bound exospheres. Dust impacts are critically important for all airless bodies considered for possible human missions in the next decade: the Moon, Near Earth Asteroids (NEAs), Phobos, and Deimos, with direct relevance to crew and mission safety and our ability to explore these objects. This talk will describe our newly developed laboratory capabilities to assess the effects of hypervelocity dust impacts on: 1) the gardening and redistribution of dust particles; and 2) the generation of ionized and neutral gasses on the surfaces of airless planetary bodies.

Hypervelocity launch capabilities to over 10 km/s

International Nuclear Information System (INIS)

Chhabildas, L.C.

1991-01-01

Very high pressure and acceleration is necessary to launch flier plates to hypervelocities. In addition, the high pressure loading must be uniform, structured, and shockless, i.e., time-dependent to prevent the flier plate from either fracturing or melting. In this paper, a novel technique is described which allows the use of megabar level loading pressures, and 10 9 g acceleration to launch intact flier plates to velocities of 12.2 km/s. 32 refs., 2 figs

HYPERFUSE: a hypervelocity inertial confinement system for fusion energy production and fission waste transmutation

International Nuclear Information System (INIS)

Makowitz, H.; Powell, J.R.; Wiswall, R.

1980-01-01

Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from a LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., 137 Cs, 90 Sr, 129 I, 99 Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,α), (n,γ), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R = 1.0 to 3.0) requirements. These studies also indicate that masses on the order of 1.0 g at densities of rho greater than or equal to 500.0 g/cm 3 are required for a practical fusion-based fission product transmutation system

Microparticle impacts at ultrahigh velocities and their relation to macroparticle impacts

International Nuclear Information System (INIS)

Walsh, J.M.; Stradling, G.L.; Idzorek, G.C.; Shafer, B.P.; Curling, H.L. Jr.

1992-01-01

The Hypervelocity Microparticle Impact project at Los Alamos has utilized electrostatically accelerated iron spheres of microscopic dimensions to generate ultra-high velocity impact experiments to about 100 km/S, an order of magnitude beyond data range for precisely controlled impact tests with ordinary macroscopic projectiles. Extreme smallness of the micro impact events brings into question whether usual shock-hydrodynamic size scaling can be assumed. Validity of size scaling (and its refinement) is questioned in the present study. Impact experiments are compared in which two impact events at a given velocity, a microscopic impact and a macroscopic impact, are essentially identical except that the projectile masses and crater volumes differ by nearly 12 orders of magnitude -- linear dimensions and times differing by 4 orders of magnitude. Strain rates at corresponding points in a deforming crater increase 4 orders of magnitude with the size reduction. Departures from exact scaling, by a factor of 3.7 in crater volume, are observed for copper targets -- with micro craters being smaller than scaling would predict. Measurement of impact craters for very small impact events leads to determination of metal yield stresses at strain rates more than two orders of magnitude greater than have been obtained by other methods. Determination of material strengths at these exceedingly high strain rates is important. Results are compared to recent theoretical models by Follansbee, Kochs and Rollett. The problem is addressed of predicting crater sizes in a target material with strain rate effects. Basic results are recalled on the late stage equivalence of hypervelocity impacts. For the strain rate dependent material to show that the curve of dimensionless crater volume versus impact velocity is replaced by a family of curves, each member of which is for one final crater size. The spacing of the curves is determined by the stress versus strain properties of the material

Nonlinear CARS measurement of nitrogen vibrational and rotational temperatures behind hypervelocity strong shock wave

Science.gov (United States)

Osada, Takashi; Endo, Youichi; Kanazawa, Chikara; Ota, Masanori; Maeno, Kazuo

2009-02-01

The hypervelocity strong shock waves are generated, when the space vehicles reenter the atmosphere from space. Behind the shock wave radiative and non-equilibrium flow is generated in front of the surface of the space vehicle. Many studies have been reported to investigate the phenomena for the aerospace exploit and reentry. The research information and data on the high temperature flows have been available to the rational heatproof design of the space vehicles. Recent development of measurement techniques with laser systems and photo-electronics now enables us to investigate the hypervelocity phenomena with greatly advanced accuracy. In this research strong shock waves are generated in low-density gas to simulate the reentry range gas flow with a free-piston double-diaphragm shock tube, and CARS (Coherent Anti-stokes Raman Spectroscopy) measurement method is applied to the hypervelocity flows behind the shock waves, where spectral signals of high space/time resolution are acquired. The CARS system consists of YAG and dye lasers, a spectroscope, and a CCD camera system. We obtain the CARS signal spectrum data by this special time-resolving experiment, and the vibrational and rotational temperatures of N2 are determined by fitting between the experimental spectroscopic profile data and theoretically estimated spectroscopic data.

Nonlinear CARS measurement of nitrogen vibrational and rotational temperatures behind hypervelocity strong shock wave

Energy Technology Data Exchange (ETDEWEB)

Osada, Takashi; Endo, Youichi [Graduate Student, Chiba University 1-33 Yayoi, Inage, Chiba, 263-8522 (Japan); Kanazawa, Chikara [Undergraduate, Chiba University 1-33 Yayoi, Inage, Chiba, 63-8522 (Japan); Ota, Masanori; Maeno, Kazuo, E-mail: maeno@faculty.chiba-u.j [Graduate School of Engineering, Chiba University 1-33 Yayoi, Inage, Chiba, 263-8522 (Japan)

2009-02-01

The hypervelocity strong shock waves are generated, when the space vehicles reenter the atmosphere from space. Behind the shock wave radiative and non-equilibrium flow is generated in front of the surface of the space vehicle. Many studies have been reported to investigate the phenomena for the aerospace exploit and reentry. The research information and data on the high temperature flows have been available to the rational heatproof design of the space vehicles. Recent development of measurement techniques with laser systems and photo-electronics now enables us to investigate the hypervelocity phenomena with greatly advanced accuracy. In this research strong shock waves are generated in low-density gas to simulate the reentry range gas flow with a free-piston double-diaphragm shock tube, and CARS (Coherent Anti-stokes Raman Spectroscopy) measurement method is applied to the hypervelocity flows behind the shock waves, where spectral signals of high space/time resolution are acquired. The CARS system consists of YAG and dye lasers, a spectroscope, and a CCD camera system. We obtain the CARS signal spectrum data by this special time-resolving experiment, and the vibrational and rotational temperatures of N{sub 2} are determined by fitting between the experimental spectroscopic profile data and theoretically estimated spectroscopic data.

Nonlinear CARS measurement of nitrogen vibrational and rotational temperatures behind hypervelocity strong shock wave

International Nuclear Information System (INIS)

Osada, Takashi; Endo, Youichi; Kanazawa, Chikara; Ota, Masanori; Maeno, Kazuo

2009-01-01

The hypervelocity strong shock waves are generated, when the space vehicles reenter the atmosphere from space. Behind the shock wave radiative and non-equilibrium flow is generated in front of the surface of the space vehicle. Many studies have been reported to investigate the phenomena for the aerospace exploit and reentry. The research information and data on the high temperature flows have been available to the rational heatproof design of the space vehicles. Recent development of measurement techniques with laser systems and photo-electronics now enables us to investigate the hypervelocity phenomena with greatly advanced accuracy. In this research strong shock waves are generated in low-density gas to simulate the reentry range gas flow with a free-piston double-diaphragm shock tube, and CARS (Coherent Anti-stokes Raman Spectroscopy) measurement method is applied to the hypervelocity flows behind the shock waves, where spectral signals of high space/time resolution are acquired. The CARS system consists of YAG and dye lasers, a spectroscope, and a CCD camera system. We obtain the CARS signal spectrum data by this special time-resolving experiment, and the vibrational and rotational temperatures of N 2 are determined by fitting between the experimental spectroscopic profile data and theoretically estimated spectroscopic data.

Plasma jet acceleration of dust particles to hypervelocities

International Nuclear Information System (INIS)

Ticos, C. M.; Wang, Zhehui; Wurden, G. A.; Kline, J. L.; Montgomery, D. S.

2008-01-01

A convenient method to accelerate simultaneously hundreds of micron-size dust particles to a few km/s over a distance of about 1 m is based on plasma drag. Plasma jets which can deliver sufficient momentum to the dust particles need to have speeds of at least several tens of km/s, densities of the order of 10 22 m -3 or higher, and low temperature ∼1 eV, in order to prevent dust destruction. An experimental demonstration of dust particles acceleration to hypervelocities by plasma produced in a coaxial gun is presented here. The plasma flow speed is deduced from photodiode signals while the plasma density is measured by streaked spectroscopy. As a result of the interaction with the plasma jet, the dust grains are also heated to high temperatures and emit visible light. A hypervelocity dust shower is imaged in situ with a high speed video camera at some distance from the coaxial gun, where light emission from the plasma flow is less intense. The bright traces of the flying microparticles are used to infer their speed and acceleration by employing the time-of-flight technique. A simple model for plasma drag which accounts for ion collection on the grain surface gives predictions for dust accelerations which are in good agreement with the experimental observations.

Hypervelocity technology carbon/carbon testing

Science.gov (United States)

Anselmo, John V.; Kretz, Lawrence O.

The paper describes the procedures used at the Structures Test Laboratory of the Wright Laboratory's Flight Dynamics Directorate to test a carbon/carbon hot structure representing a typical hypersonic gliding body, and presents the results of tests. The forebody was heated to 1371 C over 13 test runs, using radiant quartz lamps; a vertical shear force of 5.34 kN was introduced to the nose at a stabilized temperature of 816 C. Test data were collected using prototype high-temperature strain gages, in-house-designed high-temperature extensometers, conventional strain gages, and thermocouples. Video footage was taken of all test runs. Test runs were successfully completed up to 1371 C with flight typical thermal gradients at heating rates up to 5.56 C/sec. Results showed that, overall, the termal test control systems performed as predicted and that test temperatures and thermal gradients were achieved to within about 5 percent in most cases.

DebriSat - A Planned Laboratory-Based Satellite Impact Experiment for Breakup Fragment Characterizations

Science.gov (United States)

Liou, Jer-Chyi; Clark, S.; Fitz-Coy, N.; Huynh, T.; Opiela, J.; Polk, M.; Roebuck, B.; Rushing, R.; Sorge, M.; Werremeyer, M.

2013-01-01

The goal of the DebriSat project is to characterize fragments generated by a hypervelocity collision involving a modern satellite in low Earth orbit (LEO). The DebriSat project will update and expand upon the information obtained in the 1992 Satellite Orbital Debris Characterization Impact Test (SOCIT), which characterized the breakup of a 1960 s US Navy Transit satellite. There are three phases to this project: the design and fabrication of DebriSat - an engineering model representing a modern, 60-cm/50-kg class LEO satellite; conduction of a laboratory-based hypervelocity impact to catastrophically break up the satellite; and characterization of the properties of breakup fragments down to 2 mm in size. The data obtained, including fragment size, area-to-mass ratio, density, shape, material composition, optical properties, and radar cross-section distributions, will be used to supplement the DoD s and NASA s satellite breakup models to better describe the breakup outcome of a modern satellite.

Fragmentation of Millimeter-Size Hypervelocity Projectiles on Combined Mesh-Plate Bumpers

Directory of Open Access Journals (Sweden)

Aleksandr Cherniaev

2017-01-01

Full Text Available This numerical study evaluates the concept of a combined mesh-plate bumper as a shielding system protecting unmanned spacecraft from small (1 mm orbital debris impacts. Two-component bumpers consisting of an external layer of woven mesh (aluminum or steel directly applied to a surface of the aluminum plate are considered. Results of numerical modeling with a projectile velocity of 7 km/s indicate that, in comparison to the steel mesh-combined bumper, the combination of aluminum mesh and aluminum plate provides better fragmentation of small hypervelocity projectiles. At the same time, none of the combined mesh/plate bumpers provide a significant increase of ballistic properties as compared to an aluminum plate bumper. This indicates that the positive results reported in the literature for bumpers with metallic meshes and large projectiles are not scalable down to millimeter-sized particles. Based on this investigation’s results, a possible modification of the combined mesh/plate bumper is proposed for the future study.

3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies.

Science.gov (United States)

Shu, Anthony; Collette, Andrew; Drake, Keith; Grün, Eberhard; Horányi, Mihály; Kempf, Sascha; Mocker, Anna; Munsat, Tobin; Northway, Paige; Srama, Ralf; Sternovsky, Zoltán; Thomas, Evan

2012-07-01

A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Institüt für Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10(-7) torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10(-10) torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

Energy Technology Data Exchange (ETDEWEB)

Shu, Anthony; Horanyi, Mihaly; Kempf, Sascha; Thomas, Evan [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, Colorado 80303 (United States); Collette, Andrew; Drake, Keith; Northway, Paige [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, Colorado 80303 (United States); Gruen, Eberhard [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Mocker, Anna [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); IRS, Universitaet Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Munsat, Tobin [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Srama, Ralf [MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); IRS, Universitaet Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); and others

2012-07-15

A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Instituet fuer Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10{sup -7} torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10{sup -10} torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

Hypervelocity Dust Impacts in Space and the Laboratory

Science.gov (United States)

Horanyi, Mihaly; Colorado CenterLunar Dust; Atmospheric Studies (CCLDAS) Team

2013-10-01

Interplanetary dust particles continually bombard all objects in the solar system, leading to the excavation of material from the target surfaces, the production of secondary ejecta particles, plasma, neutral gas, and electromagnetic radiation. These processes are of interest to basic plasma science, planetary and space physics, and engineering to protect humans and instruments against impact damages. The Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) has recently completed a 3 MV dust accelerator, and this talk will summarize our initial science results. The 3 MV Pelletron contains a dust source, feeding positively charged micron and sub-micron sized particles into the accelerator. We will present the technical details of the facility and its capabilities, as well as the results of our initial experiments for damage assessment of optical devices, and penetration studies of thin films. We will also report on the completion of our dust impact detector, the Lunar Dust Experiment (LDEX), is expected to be flying onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission by the time of this presentation. LDEX was tested, and calibrated at our dust accelerator. We will close by offering the opportunity to use this facility by the planetary, space and plasma physics communities.

Meteorite impact in the ocean

Science.gov (United States)

Strelitz, R.

1979-01-01

In the present study, the dynamic of hypervelocity impacts and crater formation in water are examined with allowance for the unique properties of water. More precisely, the transient crater calculated is permitted to relax and act as a source of oceanic surface waves.

Shock Tunnel Studies of the Hypersonic Flowfield around the Hypervelocity Ballistic Models with Aerospikes

Science.gov (United States)

Balakalyani, G.; Saravanan, S.; Jagadeesh, G.

Reduced drag and aerodynamic heating are the two basic design requirements for any hypersonic vehicle [1]. The flowfield around an axisymmetric blunt body is characterized by a bow shockwave standing ahead of its nose. The pressure and temperature behind this shock wave are very high. This increased pressure and temperature are responsible for the high levels of drag and aerodynamic heating over the body. In the past, there have been many investigations on the use of aerospikes as a drag reduction tool. These studies on spiked bodies aim at reducing both the drag and aerodynamic heating by modifying the hypersonic flowfield ahead of the nose of the body [2]. However, most of them used very simple configurations to experimentally study the drag reduction using spikes at hypersonic speeds [3] and therefore very little experimental data is available for a realistic geometric configuration. In the present study, the standard AGARD Hypervelocity Ballistic model 1 is used as the test model. The addition of the spike to the blunt body significantly alters the flowfield ahead of the nose, leading to the formation of a low pressure conical recirculation region, thus causing a reduction in drag and wall heat flux [4]. In the present investigation, aerodynamic drag force is measured over the Hypervelocity Ballistic model-1, with and without spike, at a flow enthalpy of 1.7 MJ/kg. The experiments are carried out at a Mach number of 8 and at zero angle of attack. An internally mountable accelerometer based 3-component force balance system is used to measure the aerodynamic forces on the model. Also computational studies are carried out to complement the experiments.

Experimental demonstration of plasma-drag acceleration of a dust cloud to hypervelocities.

Science.gov (United States)

Ticoş, C M; Wang, Zhehui; Wurden, G A; Kline, J L; Montgomery, D S; Dorf, L A; Shukla, P K

2008-04-18

Simultaneous acceleration of hundreds of dust particles to hypervelocities by collimated plasma flows ejected from a coaxial gun is demonstrated. Graphite and diamond grains with radii between 5 and 30 microm, and flying at speeds up to 3.7 km/s, have been recorded with a high-speed camera. The observations agree well with a model for plasma-drag acceleration of microparticles much larger than the plasma screening length.

The Double Asteroid Redirection Test (DART)

Science.gov (United States)

Rivkin, A.; Cheng, A. F.; Stickle, A. M.; Richardson, D. C.; Barnouin, O. S.; Thomas, C.; Fahnestock, E.

2017-12-01

The Double Asteroid Redirection Test (DART) will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor. DART is currently in Preliminary Design Phase ("Phase B"), and is part of the Asteroid Impact and Deflection Assessment (AIDA), a joint ESA-NASA cooperative project. The AIDA target is the near-Earth binary asteroid 65803 Didymos, an S-class system that will make a close approach to Earth in fall 2022. The DART spacecraft is designed to impact the Didymos secondary at 6 km/s and demonstrate the ability to modify its trajectory through momentum transfer. The primary goals of AIDA are (1) perform a full-scale demonstration of the spacecraft kinetic impact technique for deflection of an asteroid; (2) measure the resulting asteroid deflection, by targeting the secondary member of a binary NEO and measuring the resulting changes of the binary orbit; and (3) study hyper-velocity collision effects on an asteroid, validating models for momentum transfer in asteroid impacts. The DART impact on the Didymos secondary will change the orbital period of the binary by several minutes, which can be measured by Earth-based optical and radar observations. The baseline DART mission launches in late 2020 to impact the Didymos secondary in 2022 near the time of its close pass of Earth, which enables an array of ground- and space-based observatories to participate in gathering data. The AIDA project will provide the first measurements of momentum transfer efficiency from hyper-velocity kinetic impact at full scale on an asteroid, where the impact conditions of the projectile are known, and physical properties and internal structures of the target asteroid are characterized or constrained. The DART kinetic impact is predicted to make a crater of 6 to 17 meters diameter, depending on target physical properties, but will also release a large volume of particulate ejecta that may be directly observable from Earth or even resolvable as a

Hyvax: A hypervelocity railgun experiment

International Nuclear Information System (INIS)

Parker, J.V.; Cummings, C.E.; Parsons, W.M.; Peterson, D.R.

1983-01-01

The experiment is designed to utilize an existing 1.89 MJ, 20 kV capacitor bark which is configured as 7 independent modules which each store 270 kJ. Projectile size is a compromise between low mass and the desire to maintain a bore diameter which is characteristic of future hypervelocity railguns. The predicted performance for this design, assuming a net driving force of 80 percent theoretical, is 23.9 km/sec with an overall efficiency of 18.4 percent. The average driving current is about 480 kA; rising from 380 kA in the first stage to 560 kA in the last stage. The projectile will be injected at 0.5 km/sec using a helium driven injector. The planned diagnostics for the railgun include voltage and current at each stage, muzzle voltage, and magnetic loop position probes at 20 locations along the barrel. Altogether 38 channels of data will be recorded on a CAMAC-based transient digitizer system. Data will be read out by a dedicated microprocessor and processed to obtain position velocity, acceleration and driving force as a function of time. In addition, a number of diagnostics will be mounted on the experimental chamber including; an x-ray shadowgraph system to look for projectile damage and to determine if the projectile is tumbling, foil switches for an independent velocity measurement, and a plasma density probe to evaluate the efficacy of various muzzle flash suppression schemes. At the present time the railgun barrel is being assembled and installed in the capacitor bank facility. We anticipate testing the first two stages in June and the full railgun in July. An experimental program of 30 shots is planned for the period July-September

Consideration of some fundamental erosion processes encountered in hypervelocity electromagnetic propulsion

International Nuclear Information System (INIS)

Buckingham, A.C.; Hawke, R.S.

1982-01-01

Experimental and theoretical research has been conducted jointly at the Livermore and Los Alamos National laboratories on dc electromagnetic railgun Lorentz accelerators. Pellets weighing a few grams to tens of grams have been launched at velocities up to better than 11 km/s. The research is addressed to attaining repeated launches of samples at hypervelocity in target impact experiments. In these experiments, shock-induced pressures in the tens of megabars range are obtained for high pressure equation-of-state research. Primary energy sources of the order of several hundred kJ to a MJ and induction currents of the order of 1 or more MA are necessary for these launches. Erosion and deformation of the conductor rails and the accelerated sample material are continuing problems. The heating, stress, and erosion resulting from simultaneous imposition of rail induction current, dense plasma (armature) interaction, current distribution, magnetic field stresses and projectile/rail contact friction are examined. It is found that while frictional heating and consequent sliding contact erosion are minor contributors to the overall erosion process, the same cannot be said for plasma impingement, penetration, and almost simultaneous induction current (Joule) heating

Advanced diagnostics for impact-flash spectroscopy on light-gas guns.

Energy Technology Data Exchange (ETDEWEB)

Breiland, William George; Reinhart, William Dodd; Miller, Paul Albert; Brown, Justin L.; Thornhill, Tom Finley, III (,; ); Mangan, Michael A.; Shaner, Eric Arthur; Chhabildas, Lalit Chandra; Grine, Albert D.; Wanke, Michael Clement; Alexander, C. Scott

2007-03-01

This study is best characterized as new technology development for implementing new sensors to investigate the optical characteristics of a rapidly expanding debris cloud resulting from hypervelocity impact regimes of 7 to 11 km/s. Our gas guns constitute a unique test bed that match operational conditions relevant to hypervelocity impact encountered in space engagements. We have demonstrated the use of (1) terahertz sensors, (2) silicon diodes for visible regimes, (3) germanium and InGaAs sensors for the near infrared regimes, and (4) the Sandia lightning detectors which are similar to the silicon diodes described in 2. The combination and complementary use of all these techniques has the strong potential of ''thermally'' characterizing the time dependent behavior of the radiating debris cloud. Complementary spectroscopic measurements provide temperature estimates of the impact generated debris by fitting its spectrum to a blackbody radiation function. This debris is time-dependent as its transport/expansion behavior is changing with time. The rapid expansion behavior of the debris cools the cloud rapidly, changing its thermal/temperature characteristics with time. A variety of sensors that span over a wide spectrum, varying from visible regime to THz frequencies, now gives us the potential to cover the impact over a broader temporal regime starting from high pressures (Mbar) high-temperatures (eV) to low pressures (mbar) low temperatures (less than room temperature) as the debris expands and cools.

Accelerator experiments with soft protons and hyper-velocity dust particles: application to ongoing projects of future X-ray missions

DEFF Research Database (Denmark)

Perinati, E.; Diebold, S.; Kendziorra, E.

2012-01-01

and hyper-velocity dust particles off X-ray mirror shells. These activities have been identified as a goal in the context of a number of ongoing space projects in order to assess the risk posed by environmental radiation and dust and qualify the adopted instrumentation with respect to possible damage...... or performance degradation. In this paper we focus on tests for the Silicon Drift Detectors (SDDs) used aboard the LOFT space mission. We use the Van de Graaff accelerators at the University of T\\"ubingen and at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg, for soft proton and hyper...

Impact of Flight Enthalpy, Fuel Simulant, and Chemical Reactions on the Mixing Characteristics of Several Injectors at Hypervelocity Flow Conditions

Science.gov (United States)

Drozda, Tomasz G.; Baurle, Robert A.; Drummond, J. Philip

2016-01-01

conditions. The mixing parameters of interest, such as mixing efficiency and total pressure recovery, are then computed and compared to the values obtained from RAS under the true enthalpy conditions and using helium and hydrogen. Finally, the impact of combustion on mixing, often deemed small enough to neglect at hypervelocity conditions, is assessed by comparing the results obtained from the hydrogen-fueled reacting and non-reacting RAS. For reacting flows, in addition to mixing efficiency and total pressure recovery, the combustion efficiency and thrust potential are also considered. In all of the simulations, the incoming air Mach number and the fuel-to-air ratio are the same, while the total pressure, total enthalpy, and the fuel simulant vary depending on the case considered. It is found that under some conditions the "cold" flow experiments are a good approximation of the flight.

The collision of a hypervelocity massive projectile with free-standing graphene: Investigation of secondary ion emission and projectile fragmentation

Science.gov (United States)

Geng, Sheng; Verkhoturov, Stanislav V.; Eller, Michael J.; Della-Negra, Serge; Schweikert, Emile A.

2017-02-01

We present here the study of the individual hypervelocity massive projectiles (440-540 keV, 33-36 km/s Au4004+ cluster) impact on 1-layer free-standing graphene. The secondary ions were detected and recorded separately from each individual impact in the transmission direction using a time-of-flight mass spectrometer. We observed C1-10± ions emitted from graphene, the projectiles which penetrated the graphene, and the Au1-3± fragment ions in mass spectra. During the projectile-graphene interaction, the projectile loses ˜15% of its initial kinetic energy (˜0.18 keV/atom, 72 keV/projectile). The Au projectiles are neutralized when approaching the graphene and then partially ionized again via electron tunneling from the hot rims of the holes on graphene, obtaining positive and negative charges. The projectile reaches an internal energy of ˜450-500 eV (˜4400-4900 K) after the impact and then undergoes a ˜90-100 step fragmentation with the ejection of Au1 atoms in the experimental time range of ˜0.1 μs.

Wake of a blunt planetary probe model under hypervelocity conditions

Energy Technology Data Exchange (ETDEWEB)

Kastell, D.; Hannemann, D.; Eitelberg, G. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Goettingen (Germany). Inst. fuer Stroemungsmechanik

1998-12-31

The flow in the wake of a planetary probe under hypervelocity re-entry conditions has two idiosyncrasies not present in the conventional (cold) hypersonic flows: the strong dissociation reaction occurring behind the bow shock wave, and the freezing of the chemical reactions of the flow by the rapid expansion at the shoulder of the probe. The aim of the present study was to both understand the relative importance of the two phenomena upon the total heat and pressure loads on a planetary probe and its possible payload as well as to provide experimental validation data for those developing numerical codes for planetary probe design and analysis. For the experimental study an instrumented blunted 140 cone was tested in the High Enthalpy Shock Tunnel in Goettingen (HEG). The numerical calculations were performed with a Thin-Layer Navier-Stokes code which is capable of simulating chemical and thermal nonequilibrium flows. For the forebody loads the prediction methods were very reliable and capable of accounting for the kinetic effects caused by the high specific enthalpy of the flow. On the other side considerable discrepancies between experimental and numerical results for the wake of the model have been observed. (orig.)

Wake of a blunt planetary probe model under hypervelocity conditions

Energy Technology Data Exchange (ETDEWEB)

Kastell, D.; Hannemann, D.; Eitelberg, G. (DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Goettingen (Germany). Inst. fuer Stroemungsmechanik)

1998-01-01

The flow in the wake of a planetary probe under hypervelocity re-entry conditions has two idiosyncrasies not present in the conventional (cold) hypersonic flows: the strong dissociation reaction occurring behind the bow shock wave, and the freezing of the chemical reactions of the flow by the rapid expansion at the shoulder of the probe. The aim of the present study was to both understand the relative importance of the two phenomena upon the total heat and pressure loads on a planetary probe and its possible payload as well as to provide experimental validation data for those developing numerical codes for planetary probe design and analysis. For the experimental study an instrumented blunted 140 cone was tested in the High Enthalpy Shock Tunnel in Goettingen (HEG). The numerical calculations were performed with a Thin-Layer Navier-Stokes code which is capable of simulating chemical and thermal nonequilibrium flows. For the forebody loads the prediction methods were very reliable and capable of accounting for the kinetic effects caused by the high specific enthalpy of the flow. On the other side considerable discrepancies between experimental and numerical results for the wake of the model have been observed. (orig.)

A SELF-CONSISTENT MODEL OF THE CIRCUMSTELLAR DEBRIS CREATED BY A GIANT HYPERVELOCITY IMPACT IN THE HD 172555 SYSTEM

International Nuclear Information System (INIS)

Johnson, B. C.; Melosh, H. J.; Lisse, C. M.; Chen, C. H.; Wyatt, M. C.; Thebault, P.; Henning, W. G.; Gaidos, E.; Elkins-Tanton, L. T.; Bridges, J. C.; Morlok, A.

2012-01-01

Spectral modeling of the large infrared excess in the Spitzer IRS spectra of HD 172555 suggests that there is more than 10 19 kg of submicron dust in the system. Using physical arguments and constraints from observations, we rule out the possibility of the infrared excess being created by a magma ocean planet or a circumplanetary disk or torus. We show that the infrared excess is consistent with a circumstellar debris disk or torus, located at ∼6 AU, that was created by a planetary scale hypervelocity impact. We find that radiation pressure should remove submicron dust from the debris disk in less than one year. However, the system's mid-infrared photometric flux, dominated by submicron grains, has been stable within 4% over the last 27 years, from the Infrared Astronomical Satellite (1983) to WISE (2010). Our new spectral modeling work and calculations of the radiation pressure on fine dust in HD 172555 provide a self-consistent explanation for this apparent contradiction. We also explore the unconfirmed claim that ∼10 47 molecules of SiO vapor are needed to explain an emission feature at ∼8 μm in the Spitzer IRS spectrum of HD 172555. We find that unless there are ∼10 48 atoms or 0.05 M ⊕ of atomic Si and O vapor in the system, SiO vapor should be destroyed by photo-dissociation in less than 0.2 years. We argue that a second plausible explanation for the ∼8 μm feature can be emission from solid SiO, which naturally occurs in submicron silicate ''smokes'' created by quickly condensing vaporized silicate.

Effect of impact angle on vaporization

Science.gov (United States)

Schultz, Peter H.

1996-09-01

Impacts into easily vaporized targets such as dry ice and carbonates generate a rapidly expanding vapor cloud. Laboratory experiments performed in a tenuous atmosphere allow deriving the internal energy of this cloud through well-established and tested theoretical descriptions. A second set of experiments under near-vacuum conditions provides a second measure of energy as the internal energy converts to kinetic energy of expansion. The resulting data allow deriving the vaporized mass as a function of impact angle and velocity. Although peak shock pressures decrease with decreasing impact angle (referenced to horizontal), the amount of impact-generated vapor is found to increase and is derived from the upper surface. Moreover, the temperature of the vapor cloud appears to decrease with decreasing angle. These unexpected results are proposed to reflect the increasing roles of shear heating and downrange hypervelocity ricochet impacts created during oblique impacts. The shallow provenance, low temperature, and trajectory of such vapor have implications for larger-scale events, including enhancement of atmospheric and biospheric stress by oblique terrestrial impacts and impact recycling of the early atmosphere of Mars.

HYPERFUSE: a novel inertial confinement system utilizing hypervelocity projectiles for fusion energy production and fission waste transmutation

International Nuclear Information System (INIS)

Makowitz, H.; Powell, J.R.; Wiswall, R.

1980-01-01

Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from an LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., 137 Cs or 90 Sr. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n, 2n), (n, α), etc.) that convert the long lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product

A SELF-CONSISTENT MODEL OF THE CIRCUMSTELLAR DEBRIS CREATED BY A GIANT HYPERVELOCITY IMPACT IN THE HD 172555 SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Johnson, B. C.; Melosh, H. J. [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States); Lisse, C. M. [JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Chen, C. H. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Wyatt, M. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Thebault, P. [LESIA, Observatoire de Paris, F-92195 Meudon Principal Cedex (France); Henning, W. G. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Gaidos, E. [Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Elkins-Tanton, L. T. [Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC 20015 (United States); Bridges, J. C. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Morlok, A., E-mail: johns477@purdue.edu [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

2012-12-10

Spectral modeling of the large infrared excess in the Spitzer IRS spectra of HD 172555 suggests that there is more than 10{sup 19} kg of submicron dust in the system. Using physical arguments and constraints from observations, we rule out the possibility of the infrared excess being created by a magma ocean planet or a circumplanetary disk or torus. We show that the infrared excess is consistent with a circumstellar debris disk or torus, located at {approx}6 AU, that was created by a planetary scale hypervelocity impact. We find that radiation pressure should remove submicron dust from the debris disk in less than one year. However, the system's mid-infrared photometric flux, dominated by submicron grains, has been stable within 4% over the last 27 years, from the Infrared Astronomical Satellite (1983) to WISE (2010). Our new spectral modeling work and calculations of the radiation pressure on fine dust in HD 172555 provide a self-consistent explanation for this apparent contradiction. We also explore the unconfirmed claim that {approx}10{sup 47} molecules of SiO vapor are needed to explain an emission feature at {approx}8 {mu}m in the Spitzer IRS spectrum of HD 172555. We find that unless there are {approx}10{sup 48} atoms or 0.05 M{sub Circled-Plus} of atomic Si and O vapor in the system, SiO vapor should be destroyed by photo-dissociation in less than 0.2 years. We argue that a second plausible explanation for the {approx}8 {mu}m feature can be emission from solid SiO, which naturally occurs in submicron silicate ''smokes'' created by quickly condensing vaporized silicate.

Hyper fuse: a novel inertial confinement system utilizing hypervelocity projectiles for fusion energy production and fission waste transmutation

International Nuclear Information System (INIS)

Makowitz, H.; Powell, J.R.; Wiswall, R.

1979-01-01

Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from an LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with a target in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., 137 Cs or 90 Sr. The 14 MeV fusion neutrons released during the pellet burn cause transmutation reactions [e.g., (n, 2n), (n, α), etc.] that convert the long lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product

Hypervelocity star candidates in Gaia DR1/TGAS

Science.gov (United States)

Marchetti, T.; Rossi, E. M.; Kordopatis, G.; Brown, A. G. A.; Rimoldi, A.; Starkenburg, E.; Youakim, K.; Ashley, R.

2018-04-01

Hypervelocity stars (HVSs) are characterized by a total velocity in excess of the Galactic escape speed, and with trajectories consistent with coming from the Galactic Centre. We apply a novel data mining routine, an artificial neural network, to discover HVSs in the TGAS subset of the first data release of the Gaia satellite, using only the astrometry of the stars. We find 80 stars with a predicted probability >90% of being HVSs, and we retrieved radial velocities for 47 of those. We discover 14 objects with a total velocity in the Galactic rest frame >400 km s-1, and 5 of these have a probability >50% of being unbound from the Milky Way. Tracing back orbits in different Galactic potentials, we discover 1 HVS candidate, 5 bound HVS candidates, and 5 runaway star candidates with remarkably high velocities, between 400 and 780 km s-1. We wait for future Gaia releases to confirm the goodness of our sample and to increase the number of HVS candidates.

FTIR Analyses of Hypervelocity Impact Deposits: DebriSat Tests

Science.gov (United States)

2015-03-27

DEPT SPACE MATERIALS LABORATORY ENGINEERING & TECHNOLOGY GROUP Shant Kenderian, DIRECTOR DEPT MATERIALS PROCESSING DEPT SPACE MATERIALS LABORATORY...ENGINEERING & TECHNOLOGY GROUP © The Aerospace Corporation, 2015. All trademarks, service marks, and trade names are the property of their respective owners...mitchell.nolan.ctr@us.af.mil SECURITY CLASSIFICATION UNCLASSIFIED Brian Roebuck AEDC brian.roebuck@us.af.mil Norman Fitz-Coy University of Florida nfc

Heat-transfer distributions on biconics at incidence in hypersonic-hypervelocity He, N2, air, and CO2 flows

Science.gov (United States)

Miller, C. G.; Micol, J. R.; Gnoffo, P. A.; Wilder, S.E.

1983-01-01

Laminar heat-transfer rates were measured on spherically blunted, 13 degrees/F degrees on-axis and bent biconics (fore cone bent 7 degrees upward relative to aft cone) at hypersonic-hypervelocity flow conditions in the Langley Expansion Tube. Freestream velocities from 4.5 to 6.9 km/sec and Mach numbers from 6 to 9 were generated using helium, nitrogen, air, and carbon dioxide test gases, resulting in normal shock density ratios from 4 to 19. Angle of attack, referenced to the axis of the aft cone, was varied from zero to 20 degrees in 4 degree increments. The effect of nose bend, angle of attack, and real-gas phenomena on heating distributions are presented along with comparisons of measurement to prediction from a code which solves the three-dimensional 'parabolized Navier-Stokes' equations.

Predicted space motions for hypervelocity and runaway stars: proper motions and radial velocities for the Gaia Era

Energy Technology Data Exchange (ETDEWEB)

Kenyon, Scott J.; Brown, Warren R.; Geller, Margaret J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Bromley, Benjamin C., E-mail: skenyon@cfa.harvard.edu, E-mail: wbrown@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: bromley@physics.utah.edu [Department of Physics, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States)

2014-10-01

We predict the distinctive three-dimensional space motions of hypervelocity stars (HVSs) and runaway stars moving in a realistic Galactic potential. For nearby stars with distances less than 10 kpc, unbound stars are rare; proper motions alone rarely isolate bound HVSs and runaways from indigenous halo stars. At large distances of 20-100 kpc, unbound HVSs are much more common than runaways; radial velocities easily distinguish both from indigenous halo stars. Comparisons of the predictions with existing observations are encouraging. Although the models fail to match observations of solar-type HVS candidates from SEGUE, they agree well with data for B-type HVS and runaways from other surveys. Complete samples of g ≲ 20 stars with Gaia should provide clear tests of formation models for HVSs and runaways and will enable accurate probes of the shape of the Galactic potential.

Engineering Polymer Blends for Impact Damage Mitigation

Science.gov (United States)

Gordon, Keith L.; Smith, Russell W.; Working, Dennis C.; Siochi, Emilie J.

2016-01-01

Structures containing polymers such as DuPont's Surlyn® 8940, demonstrate puncture healing when impacted by a 9 millimeter projectile traveling from speeds near 300 meters per second (1,100 feet per second) to hypervelocity impacts in the micrometeoroid velocity range of 5 kilometers per second (16,000 feet per second). Surlyn® 8940 puncture heals over a temperature range of minus 30 degrees Centigrade to plus 70 degrees Centigrade and shows potential for use in pressurized vessels subject to impact damage. However, such polymers are difficult to process and limited in applicability due to their low thermal stability, poor chemical resistance and overall poor mechanical properties. In this work, several puncture healing engineered melt formulations were developed. Moldings of melt blend formulations were impacted with a 5.56 millimeter projectile with a nominal velocity of 945 meters per second (3,100 feet per second) at about 25 degrees Centigrade, 50 degrees Centigrade and 100 degrees Centigrade, depending upon the specific blend being investigated. Self-healing tendencies were determined using surface vacuum pressure tests and tensile tests after penetration using tensile dog-bone specimens (ASTM D 638-10). For the characterization of tensile properties both pristine and impacted specimens were tested to obtain tensile modulus, yield stress and tensile strength, where possible. Experimental results demonstrate a range of new puncture healing blends which mitigate damage in the ballistic velocity regime.

The impact imperative: Laser ablation for deflecting asteroids, meteoroids, and comets from impacting the earth

Energy Technology Data Exchange (ETDEWEB)

Campbell, Jonathan W [Advanced Projects/FD02, National Space Science and Technology Center, NASA/MSFC, Huntsville, Alabama, 35812 (United States); Phipps, Claude [Photonics Associates 200A Ojo de la Vaca Road Santa Fe, NM 87505 (United States); Smalley, Larry [Department of Physics, University of Alabama, Huntsville (United States); Reilly, James [Northeast Science and Technology, East Sandwich, MA (United States); Boccio, Dona [Queensborough Community College of the City, University of New York, New York (United States)

2003-05-14

Impacting at hypervelocity, an asteroid struck the Earth approximately 65 million years ago in the Yucatan Peninsula area. This triggered the extinction of almost 70% of the species of life on Earth including the dinosaurs. Other impacts prior to this one have caused even greater extinctions. Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most important immediate space challenge facing human civilization. This is the Impact Imperative. We now believe that while there are about 2000 earth orbit crossing rocks greater than 1 kilometer in diameter, there may be as many as 200,000 or more objects in the 100 m size range. Can anything be done about this fundamental existence question facing our civilization? The answer is a resounding yes{exclamation_point} By using an intelligent combination of Earth and space based sensors coupled with an infra-structure of high-energy laser stations and other secondary mitigation options, we can deflect inbound asteroids, meteoroids, and comets and prevent them from striking the Earth. This can be accomplished by irradiating the surface of an inbound rock with sufficiently intense pulses so that ablation occurs. This ablation acts as a small rocket incrementally changing the shape of the rock's orbit around the Sun. One-kilometer size rocks can be moved sufficiently in about a month while smaller rocks may be moved in a shorter time span.

The impact imperative: Laser ablation for deflecting asteroids, meteoroids, and comets from impacting the earth

International Nuclear Information System (INIS)

Campbell, Jonathan W.; Phipps, Claude; Smalley, Larry; Reilly, James; Boccio, Dona

2003-01-01

Impacting at hypervelocity, an asteroid struck the Earth approximately 65 million years ago in the Yucatan Peninsula area. This triggered the extinction of almost 70% of the species of life on Earth including the dinosaurs. Other impacts prior to this one have caused even greater extinctions. Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most important immediate space challenge facing human civilization. This is the Impact Imperative. We now believe that while there are about 2000 earth orbit crossing rocks greater than 1 kilometer in diameter, there may be as many as 200,000 or more objects in the 100 m size range. Can anything be done about this fundamental existence question facing our civilization? The answer is a resounding yes! By using an intelligent combination of Earth and space based sensors coupled with an infra-structure of high-energy laser stations and other secondary mitigation options, we can deflect inbound asteroids, meteoroids, and comets and prevent them from striking the Earth. This can be accomplished by irradiating the surface of an inbound rock with sufficiently intense pulses so that ablation occurs. This ablation acts as a small rocket incrementally changing the shape of the rock's orbit around the Sun. One-kilometer size rocks can be moved sufficiently in about a month while smaller rocks may be moved in a shorter time span

Racemization of Valine by Impact-Induced Heating

Science.gov (United States)

Furukawa, Yoshihiro; Takase, Atsushi; Sekine, Toshimori; Kakegawa, Takeshi; Kobayashi, Takamichi

2018-03-01

Homochirality plays an important role in all living organisms but its origin remains unclear. It also remains unclear whether such chiral molecules survived terrestrial heavy impact events. Impacts of extraterrestrial objects on early oceans were frequent and could have affected the chirality of oceanic amino acids when such amino acids accumulated during impacts. This study investigated the effects of shock-induced heating on enantiomeric change of valine with minerals such as olivine ([Mg0.9, Fe0.1]2SiO4), hematite (Fe2O3), and calcite (CaCO3). With a shock wave generated by an impact at 0.8 km/s, both d- and l-enriched valine were significantly decomposed and partially racemized under all experimental conditions. Different minerals had different shock impedances; therefore, they provided different P-T conditions for identical impacts. Furthermore, the high pH of calcite promoted the racemization of valine. The results indicate that in natural hypervelocity impacts, amino acids in shocked oceanic water would have decomposed completely, since impact velocity and the duration of shock compression and heating are typically greater in hypervelocity impact events than those in experiments. Even with the shock wave by the impact of small and decelerated projectiles in which amino acids survive, the shock heating may generate sufficient heat for significant racemization in shocked oceanic water. However, the duration of shock induced heating by small projectiles is limited and the population of such decelerated projectiles would be limited. Therefore, even though impacts of asteroids and meteorites were frequent on the prebiotic Earth, impact events would not have significantly changed the ee of proteinogenic amino acids accumulated in the entire ocean.

Shielding requirements for the Space Station habitability modules

Science.gov (United States)

Avans, Sherman L.; Horn, Jennifer R.; Williamsen, Joel E.

1990-01-01

The design, analysis, development, and tests of the total meteoroid/debris protection system for the Space Station Freedom habitability modules, such as the habitation module, the laboratory module, and the node structures, are described. Design requirements are discussed along with development efforts, including a combination of hypervelocity testing and analyses. Computer hydrocode analysis of hypervelocity impact phenomena associated with Space Station habitability structures is covered and the use of optimization techniques, engineering models, and parametric analyses is assessed. Explosive rail gun development efforts and protective capability and damage tolerance of multilayer insulation due to meteoroid/debris impact are considered. It is concluded that anticipated changes in the debris environment definition and requirements will require rescoping the tests and analysis required to develop a protection system.

Hypervelocity impact of tungsten cubes on spaced armour

International Nuclear Information System (INIS)

Chandel, Pradeep S; Sood, Dharmanshu; Kumar, Rajeev; Sharma, Prince; Sewak, Bhupinder; Bhardwaj, Vikas; Athwal, Manoj; Mangla, Vikas; Biswas, Ipsita; Singh, Manjit

2012-01-01

The paper summarizes the experimental observations and simulation studies of damage potential of tungsten alloy cubes on relatively thin mild steel spaced armour target plates in the velocity regime 1300 – 4000 ms −1 using Two Stage Light Gas Gun technique. The cubes of size 9.5 mm and 12 mm having mass 15 g and 30 g respectively were made to impact normally on three target plates of size 300 mm × 300 mm of thickness 4, 4 and 10 mm at 100 mm distance apart. Flash radiography has been used to image the projectile-target interaction in the nitrogen environment at 300 mbar vacuum at room temperature. The results reveal clear perforation by 9.5 mm cube in all the three target plates up to impact velocity of about 2000 m/s. While 12 mm cube can perforate the spaced armour upto impact velocity of 4000 m/s. This shows that 9.5mm tungsten alloy cube is not effective beyond 2000 m/s while 12 mm tungsten alloy cube can defeat the spaced armour upto 4000 m/s. The simulation studies have been carried out using Autodyn 3D nonlinear code using Lagrange solver at velocities 1200 – 4000 m/s. The simulation results are in good agreement with the experimental findings.

Methods for Analysis and Simulation of Ballistic Impact

Science.gov (United States)

2017-04-01

carbide. All experiments were conducted in reverse mode [7], with long- rod hypervelocity impact and penetration into confined cylindrical ceramic...comprehensive treatment that encompasses curvilinear coordinates, see [17], with general kinematics addressed in more detail in [49]. Governing equations of...deformation and mechanically reversible changes in damage (e.g., elastic crack closure on load release), J accounts for plastic slip from dislocations

CARS measurement of vibrational and rotational temperature with high power laser and high speed visualization of total radiation behind hypervelocity shock waves of 5-7km/s

Science.gov (United States)

Sakurai, Kotaro; Bindu, Venigalla Hima; Niinomi, Shota; Ota, Masanori; Maeno, Kazuo

2010-09-01

Coherent Anti-Stokes Raman Spectroscopy (CARS) method is commonly used for measuring molecular structure or condition. In the aerospace technology, this method is applies to measure the temperature in thermic fluid with relatively long time duration of millisecond or sub millisecond. On the other hand, vibrational/rotational temperatures behind hypervelocity shock wave are important for heat-shield design in phase of reentry flight. The non-equilibrium flow with radiative heating from strongly shocked air ahead of the vehicles plays an important role on the heat flux to the wall surface structure as well as convective heating. In this paper CARS method is applied to measure the vibrational/rotational temperature of N2 behind hypervelocity shock wave. The strong shock wave in front of the reentering space vehicles can be experimentally realigned by free-piston, double-diaphragm shock tube with low density test gas. However CARS measurement is difficult for our experiment. Our measurement needs very short pulse which order of nanosecond and high power laser for CARS method. It is due to our measurement object is the momentary phenomena which velocity is 7km/s. In addition the observation section is low density test gas, and there is the strong background light behind the shock wave. So we employ the CARS method with high power, order of 1J/pulse, and very short pulse (10ns) laser. By using this laser the CARS signal can be acquired even in the strong radiation area. Also we simultaneously try to use the CCD camera to obtain total radiation with CARS method.

Time-resolved wave-profile measurements at impact velocities of 10 km/s

Energy Technology Data Exchange (ETDEWEB)

Chhabildas, L.C.; Furnish, M.D.; Reinhart, W.D.

1998-06-01

Development of well-controlled hypervelocity launch capabilities is the first step to understand material behavior at extreme pressures and temperatures not available using conventional gun technology. In this paper, techniques used to extend both the launch capabilities of a two-stage light-gas gun to 10 km/s and their use to determine material properties at pressures and temperature states higher than those ever obtained in the laboratory are summarized. Time-resolved interferometric techniques have been used to determine shock loading and release characteristics of materials impacted by titanium and aluminum fliers launched by the only developed three-stage light-gas gun at 10 km/s. In particular, the Sandia three stage light gas gun, also referred to as the hypervelocity launcher, HVL, which is capable of launching 0.5 mm to 1.0 mm thick by 6 mm to 19 mm diameter plates to velocities approaching 16 km/s has been used to obtain the necessary impact velocities. The VISAR, interferometric particle-velocity techniques has been used to determine shock loading and release profiles in aluminum and titanium at impact velocities of 10 km/s.

MMT hypervelocity star survey. III. The complete survey

Energy Technology Data Exchange (ETDEWEB)

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J., E-mail: wbrown@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: skenyon@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

2014-05-20

We describe our completed spectroscopic survey for unbound hypervelocity stars (HVSs) ejected from the Milky Way. Three new discoveries bring the total number of unbound late B-type stars to 21. We place new constraints on the nature of the stars and on their distances using moderate resolution MMT spectroscopy. Half of the stars are fast rotators; they are certain 2.5-4 M {sub ☉} main sequence stars at 50-120 kpc distances. Correcting for stellar lifetime, our survey implies that unbound 2.5-4 M {sub ☉} stars are ejected from the Milky Way at a rate of 1.5 × 10{sup –6} yr{sup –1}. These unbound HVSs are likely ejected continuously over the past 200 Myr and do not share a common flight time. The anisotropic spatial distribution of HVSs on the sky remains puzzling. Southern hemisphere surveys like SkyMapper will soon allow us to map the all-sky distribution of HVSs. Future proper motion measurements with Hubble Space Telescope and Gaia will provide strong constraints on origin. Existing observations are all consistent with HVS ejections from encounters with the massive black hole in the Galactic center.

MMT hypervelocity star survey. III. The complete survey

International Nuclear Information System (INIS)

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.

2014-01-01

We describe our completed spectroscopic survey for unbound hypervelocity stars (HVSs) ejected from the Milky Way. Three new discoveries bring the total number of unbound late B-type stars to 21. We place new constraints on the nature of the stars and on their distances using moderate resolution MMT spectroscopy. Half of the stars are fast rotators; they are certain 2.5-4 M ☉ main sequence stars at 50-120 kpc distances. Correcting for stellar lifetime, our survey implies that unbound 2.5-4 M ☉ stars are ejected from the Milky Way at a rate of 1.5 × 10 –6 yr –1 . These unbound HVSs are likely ejected continuously over the past 200 Myr and do not share a common flight time. The anisotropic spatial distribution of HVSs on the sky remains puzzling. Southern hemisphere surveys like SkyMapper will soon allow us to map the all-sky distribution of HVSs. Future proper motion measurements with Hubble Space Telescope and Gaia will provide strong constraints on origin. Existing observations are all consistent with HVS ejections from encounters with the massive black hole in the Galactic center.

Hypervelocity stars from young stellar clusters in the Galactic Centre

Science.gov (United States)

Fragione, G.; Capuzzo-Dolcetta, R.; Kroupa, P.

2017-05-01

The enormous velocities of the so-called hypervelocity stars (HVSs) derive, likely, from close interactions with massive black holes, binary stars encounters or supernova explosions. In this paper, we investigate the origin of HVSs as consequence of the close interaction between the Milky Way central massive black hole and a passing-by young stellar cluster. We found that both single and binary HVSs may be generated in a burst-like event, as the cluster passes near the orbital pericentre. High-velocity stars will move close to the initial cluster orbital plane and in the direction of the cluster orbital motion at the pericentre. The binary fraction of these HVS jets depends on the primordial binary fraction in the young cluster. The level of initial mass segregation determines the value of the average mass of the ejected stars. Some binary stars will merge, continuing their travel across and out of the Galaxy as blue stragglers.

Effect of compressibility on the hypervelocity penetration

Science.gov (United States)

Song, W. J.; Chen, X. W.; Chen, P.

2018-02-01

We further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity penetration. Meanwhile, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.

Discovery of Two New Hypervelocity Stars from the LAMOST Spectroscopic Surveys

Energy Technology Data Exchange (ETDEWEB)

Huang, Y.; Liu, X.-W.; Chen, B.-Q. [South-Western Institute for Astronomy Research, Yunnan University, Kunming 650500 (China); Zhang, H.-W.; Wang, C.; Tian, Z.-J. [Department of Astronomy, Peking University, Beijing 100871 (China); Xiang, M.-S.; Li, Y.-B. [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Yuan, H.-B. [Department of Astronomy, Beijing Normal University, Beijing 100875 (China); Wang, B., E-mail: yanghuang@pku.edu.cn, E-mail: x.liu@pku.edu.cn, E-mail: zhanghw@pku.edu.cn [Key Laboratory for the Structure and Evolution of Celestial Objects, Yunnan Observatories, CAS, Kunming 650216 (China)

2017-09-20

We report the discovery of two new unbound hypervelocity stars (HVSs) from the LAMOST spectroscopic surveys. They are, respectively, a B2V-type star of ∼7 M {sub ⊙} with a Galactic rest-frame radial velocity of 502 km s{sup −1} at a Galactocentric radius of ∼21 kpc and a B7V-type star of ∼4 M {sub ⊙} with a Galactic rest-frame radial velocity of 408 km s{sup −1} at a Galactocentric radius of ∼30 kpc. The origins of the two HVSs are not clear given their currently poorly measured proper motions. However, the future data releases of Gaia should provide proper motion measurements accurate enough to solve this problem. The ongoing LAMOST spectroscopic surveys are expected to yield more HVSs to form a statistical sample, providing vital constraints on understanding the nature of HVSs and their ejection mechanisms.

IADC Vulnerability Report, IT32-21

Science.gov (United States)

Christiansen, E. L.; Miller, J. E.; Hyde, J.

2016-01-01

Numerous mission support hardware systems and their spares are maintained outside of the habitable volume of the International Space Station (ISS), and are arranged covered by a multi-layer insulation (MLI) thermal blanket which provides both thermal control and a measure of protection from micrometeoroids and orbital debris (MMOD). The NASA Hypervelocity Impact Technology (HVIT) group at the Johnson Space Center in Houston Texas has assessed the protection provided by MLI in a series of hypervelocity impact tests using a 1 mm thick aluminum 6061-T6 rear wall to simulate the actual hardware behind the MLI. HVIT has also evaluated methods to enhance the protection provided by MLI thermal blankets. The impact study used both aluminum and steel spherical projectiles accelerated to speeds of 7 km/s using a 4.3 mm, two-stage, light-gas gun at the NASA White Sands Test Facility (WSTF).

Rail Impact Testing. Test Operations Procedure (TOP)

Science.gov (United States)

2008-09-15

impact test. The rail impact test is used to verify structural integrity of the test item and the adequacy of the tie-down system and tie-down...strength of provisions, connection and supporting structural frame, paragraph 5.2.3 ** Superscript...parts, to include outriggers and booms) without advanced approval by SDDCTEA. Torque nuts on wire rope clips to their correct value. Torque cable

Hypervelocity Impact Testing of Materials for Additive Construction: Applications on Earth, the Moon, and Mars

Science.gov (United States)

Ordonez, Erick; Edmunson, Jennifer; Fiske, Michael; Christiansen, Eric; Miller, Josh; Davis, Bruce Alan; Read, Jon; Johnston, Mallory; Fikes, John

2017-01-01

Additive Construction is the process of building infrastructure such as habitats, garages, roads, berms, etcetera layer by layer (3D printing). The National Aeronautics and Space Administration (NASA) and the United States Army Corps of Engineers (USACE) are pursuing additive construction to build structures using resources available in-situ. Using materials available in-situ reduces the cost of planetary missions and operations in theater. The NASA team is investigating multiple binders that can be produced on planetary surfaces, including the magnesium oxide-based Sorel cement; the components required to make Ordinary Portland Cement (OPC), the common cement used on Earth, have been found on Mars. The availability of OPC-based concrete on Earth drove the USACE to pursue additive construction for base housing and barriers for military operations. Planetary and military base structures must be capable of resisting micrometeoroid impacts with velocities ranging from 11 to 72km/s for particle sizes 200 micrometers or more (depending on protection requirements) as well as bullets and shrapnel with a velocity of 1.036km/s with projectiles 5.66mm diameter and 57.40mm in length, respectively.

BINARY DISRUPTION BY MASSIVE BLACK HOLES: HYPERVELOCITY STARS, S STARS, AND TIDAL DISRUPTION EVENTS

Energy Technology Data Exchange (ETDEWEB)

Bromley, Benjamin C. [Department of Physics and Astronomy, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States); Kenyon, Scott J.; Geller, Margaret J.; Brown, Warren R., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: wbrown@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

2012-04-20

We examine whether disrupted binary stars can fuel black hole growth. In this mechanism, tidal disruption produces a single hypervelocity star (HVS) ejected at high velocity and a former companion star bound to the black hole. After a cluster of bound stars forms, orbital diffusion allows the black hole to accrete stars by tidal disruption at a rate comparable to the capture rate. In the Milky Way, HVSs and the S star cluster imply similar rates of 10{sup -5} to 10{sup -3} yr{sup -1} for binary disruption. These rates are consistent with estimates for the tidal disruption rate in nearby galaxies and imply significant black hole growth from disrupted binaries on 10 Gyr timescales.

Thermal protection for hypervelocity flight in earth's atmosphere by use of radiation backscattering ablating materials

Science.gov (United States)

Howe, John T.; Yang, Lily

1991-01-01

A heat-shield-material response code predicting the transient performance of a material subject to the combined convective and radiative heating associated with the hypervelocity flight is developed. The code is dynamically interactive to the heating from a transient flow field, including the effects of material ablation on flow field behavior. It accomodates finite time variable material thickness, internal material phase change, wavelength-dependent radiative properties, and temperature-dependent thermal, physical, and radiative properties. The equations of radiative transfer are solved with the material and are coupled to the transfer energy equation containing the radiative flux divergence in addition to the usual energy terms.

MMT HYPERVELOCITY STAR SURVEY. II. FIVE NEW UNBOUND STARS

Energy Technology Data Exchange (ETDEWEB)

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J., E-mail: wbrown@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: skenyon@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

2012-05-20

We present the discovery of five new unbound hypervelocity stars (HVSs) in the outer Milky Way halo. Using a conservative estimate of Galactic escape velocity, our targeted spectroscopic survey has now identified 16 unbound HVSs as well as a comparable number of HVSs ejected on bound trajectories. A Galactic center origin for the HVSs is supported by their unbound velocities, the observed number of unbound stars, their stellar nature, their ejection time distribution, and their Galactic latitude and longitude distribution. Other proposed origins for the unbound HVSs, such as runaway ejections from the disk or dwarf galaxy tidal debris, cannot be reconciled with the observations. An intriguing result is the spatial anisotropy of HVSs on the sky, which possibly reflects an anisotropic potential in the central 10-100 pc region of the Galaxy. Further progress requires measurement of the spatial distribution of HVSs over the southern sky. Our survey also identifies seven B supergiants associated with known star-forming galaxies; the absence of B supergiants elsewhere in the survey implies there are no new star-forming galaxies in our survey footprint to a depth of 1-2 Mpc.

High speed photography of the plasma flow and the projectiles in the T.U.M. hypervelocity accelerator

International Nuclear Information System (INIS)

Igenbergs, E.; Kuczera, H.; Schroeder, B.

1979-01-01

The hypervelocity accelerator at the Technische Universitaet Muenchen, FRG, accelerates small projectiles (0.1 to 1.0 mm diameter) to velocities around 20 km/s. The photographic equipment consists of two Cordin single-frame image converter cameras and one TRW image converter camera with streak units and multiple-frame units. They are used for plasma flow diagnostics and the measurement of the position and the velocity of the projectiles. The single-frame cameras are triggered with a Laser light bar and the photographic measurement of the projectile velocity will be compared with Doppler-Radar. (author)

CANFLEX fuel bundle impact test

International Nuclear Information System (INIS)

Chang, Seok Kyu; Chung, C. H.; Park, J. S.; Hong, S. D.; Kim, B. D.

1997-08-01

This document outlines the test results for the impact test of the CANFLEX fuel bundle. Impact test is performed to determine and verify the amount of general bundle shape distortion and defect of the pressure tube that may occur during refuelling. The test specification requires that the fuel bundles and the pressure tube retain their integrities after the impact test under the conservative conditions (10 stationary bundles with 31kg/s flow rate) considering the pressure tube creep. The refuelling simulator operating with pneumatic force and simulated shield plug were fabricated and the velocity/displacement transducer and the high speed camera were also used in this test. The characteristics of the moving bundle (velocity, displacement, impacting force) were measured and analyzed with the impact sensor and the high speed camera system. The important test procedures and measurement results were discussed as follows. 1) Test bundle measurements and the pressure tube inspections 2) Simulated shield plug, outlet flange installation and bundle loading 3) refuelling simulator, inlet flange installation and sensors, high speed camera installation 4) Perform the impact test with operating the refuelling simulator and measure the dynamic characteristics 5) Inspections of the fuel bundles and the pressure tube. (author). 8 refs., 23 tabs., 13 figs

Orion Ground Test Article Water Impact Tests: Photogrammetric Evaluation of Impact Conditions

Science.gov (United States)

Vassilakos, Gregory J.; Mark, Stephen D.

2018-01-01

The Ground Test Article (GTA) is an early production version of the Orion Crew Module (CM). The structural design of the Orion CM is being developed based on LS-DYNA water landing simulations. As part of the process of confirming the accuracy of LS-DYNA water landing simulations, the GTA water impact test series was conducted at NASA Langley Research Center (LaRC) to gather data for comparison with simulations. The simulation of the GTA water impact tests requires the accurate determination of the impact conditions. To accomplish this, the GTA was outfitted with an array of photogrammetry targets. The photogrammetry system utilizes images from two cameras with a specialized tracking software to determine time histories for the 3-D coordinates of each target. The impact conditions can then be determined from the target location data.

Formation and spatial distribution of hypervelocity stars in AGN outflows

Science.gov (United States)

Wang, Xiawei; Loeb, Abraham

2018-05-01

We study star formation within outflows driven by active galactic nuclei (AGN) as a new source of hypervelocity stars (HVSs). Recent observations revealed active star formation inside a galactic outflow at a rate of ∼ 15M⊙yr-1 . We verify that the shells swept up by an AGN outflow are capable of cooling and fragmentation into cold clumps embedded in a hot tenuous gas via thermal instabilities. We show that cold clumps of ∼ 103 M⊙ are formed within ∼ 105 yrs. As a result, stars are produced along outflow's path, endowed with the outflow speed at their formation site. These HVSs travel through the galactic halo and eventually escape into the intergalactic medium. The expected instantaneous rate of star formation inside the outflow is ∼ 4 - 5 orders of magnitude greater than the average rate associated with previously proposed mechanisms for producing HVSs, such as the Hills mechanism and three-body interaction between a star and a black hole binary. We predict the spatial distribution of HVSs formed in AGN outflows for future observational probe.

Laboratory study of hyper-elocity impact-driven chemical reactions and surface evolution in icy targets.

Science.gov (United States)

Ulibarri, Z.; Munsat, T.; Dee, R.; Horanyi, M.; James, D.; Kempf, S.; Nagle, M.; Sternovsky, Z.

2017-12-01

Although ice is prevalent in the solar system and the long-term evolution of many airless icy bodies is affected by hypervelocity micrometeoroid bombardment, there has been little experimental investigation into these impact phenomena, especially at the impact speeds encountered in space. For example, there is little direct information about how dust impacts alter the local chemistry, and dust impacts may be an important mechanism for creating complex organic molecules necessary for life. Laser ablation and light-gas gun experiments simulating dust impacts have successfully created amino acid precursors from base components in ice surfaces. Additionally, the Cassini mission revealed CO2 deposits in icy satellites of Saturn, which may have been created by dust impacts. With the creation of a cryogenically cooled ice target for the dust accelerator facility at the NASA SSERVI-funded Institute for Modeling Plasma, Atmospheres, and Cosmic Dust (IMPACT), it is now possible to study the effects of micrometeoroid impacts in a controlled environment under conditions and at energies typically encountered in nature. Complex ice-target mixtures are created with a flash-freezing target which allows for homogeneous mixtures to be frozen in place even with salt mixtures that otherwise would form inhomogeneous ice surfaces. Coupled with the distinctive capabilities of the IMPACT dust facility, highly valuable data concerning the evolution of icy bodies under hypervelocity bombardment and the genesis of complex organic chemistry on these icy bodies can be gathered in unique and tightly controlled experiments. Results from recent and ongoing investigations will be presented.

Detecting dust hits at Enceladus, Saturn and beyond using CAPS / ELS data from Cassini

Science.gov (United States)

Vandegriff, J. D.; Stoneberger, P. J.; Jones, G.; Waite, J. H., Jr.

2016-12-01

It has recently been shown (1) that the impact of hypervelocity dust grains on the Cassini spacecraft can be detected by the Cassini Plasma Spectrometer (CAPS) Electron Spectrometer (ELS) instrument. For multiple Enceladus flybys, fine scale features in the lower energy regime of ELS energy spectra can be explained as short-duration, isotropic plasma clouds due to dust impacts. We have developed an algorithm for detecting these hypervelocity dust impacts, and the list of such impacts during Enceladus flybys will be presented. We also present preliminary results obtained when using the algorithm to search for dust impacts in other regions of Saturn's magnetosphere as well as in the solar wind. (1) Jones, Geraint, Hypervelocity dust impact signatures detected by Cassini CAPS-ELS in the Enceladus plume, MOP Meeting, June 1-5, 2015, Atlanta, GA

The Microstructure of Lunar Micrometeorite Impact Craters

Science.gov (United States)

Noble, S. K.; Keller, L. P.; Christoffersen, R.; Rahman, Z.

2016-01-01

The peak of the mass flux of impactors striking the lunar surface is made up of objects approximately 200 micrometers in diameter that erode rocks, comminute regolith grains, and produce agglutinates. The effects of these micro-scale impacts are still not fully understood. Much effort has focused on evaluating the physical and optical effects of micrometeorite impacts on lunar and meteoritic material using pulsed lasers to simulate the energy deposited into a substrate in a typical hypervelocity impact. Here we characterize the physical and chemical changes that accompany natural micrometeorite impacts into lunar rocks with long surface exposure to the space environment (12075 and 76015). Transmission electron microscope (TEM) observations were obtained from cross-sections of approximately 10-20 micrometers diameter craters that revealed important micro-structural details of micrometeorite impact processes, including the creation of npFe (sup 0) in the melt, and extensive deformation around the impact site.

An Innovative Solution to NASA's NEO Impact Threat Mitigation Grand Challenge and Flight Validation Mission Architecture Development

Data.gov (United States)

National Aeronautics and Space Administration — A Hypervelocity Asteroid Intercept Vehicle (HAIV) mission architecture, which blends a hypervelocity kinetic impactor with a subsurface nuclear explosion for optimal...

Molecular dynamics simulation of impact test

International Nuclear Information System (INIS)

Akahoshi, Y.; Schmauder, S.; Ludwig, M.

1998-01-01

This paper describes an impact test by molecular dynamics (MD) simulation to evaluate embrittlement of bcc Fe at different temperatures. A new impact test model is developed for MD simulation. The typical fracture behaviors show transition from brittle to ductile fracture, and a history of the impact loads also demonstrates its transition. We conclude that the impact test by MD could be feasible. (orig.)

Molecular dynamics simulation of impact test

Energy Technology Data Exchange (ETDEWEB)

Akahoshi, Y. [Kyushu Inst. of Tech., Kitakyushu, Fukuoka (Japan); Schmauder, S.; Ludwig, M. [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt

1998-11-01

This paper describes an impact test by molecular dynamics (MD) simulation to evaluate embrittlement of bcc Fe at different temperatures. A new impact test model is developed for MD simulation. The typical fracture behaviors show transition from brittle to ductile fracture, and a history of the impact loads also demonstrates its transition. We conclude that the impact test by MD could be feasible. (orig.)

Hypervelocity Microparticle Impact Studies: Simulating Cosmic Dust Impacts on the Dustbuster

Science.gov (United States)

Austin, D. E.; Manning, H. L. K.; Bailey, C. L.; Farnsworth, J. T.; Ahrens, T. J.; Beauchamp, J. L.

2002-01-01

Iron and copper microparticles accelerated to 2-20 km/s in a 2 MV Van de Graaff accelerator were used to test a recently-developed cosmic dust mass spectrometer, known as the Dustbuster. Additional information is contained in the original extended abstract.

New Laboratory-Based Satellite Impact Experiments for Breakup Fragment Characterization

Science.gov (United States)

Liou, J.-C.; Fitz-Coy, N.; Dikova, R.; Wilson, M.; Huynh, T.; Sorge, M.; Sheaffer, P.; Opiela, J.; Cowardin, H.; Krisko, P.;

High Pressure Quick Disconnect Particle Impact Tests

Science.gov (United States)

Rosales, Keisa R.; Stoltzfus, Joel M.

2009-01-01

NASA Johnson Space Center White Sands Test Facility (WSTF) performed particle impact testing to determine whether there is a particle impact ignition hazard in the quick disconnects (QDs) in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). Testing included standard supersonic and subsonic particle impact tests on 15-5 PH stainless steel, as well as tests performed on a QD simulator. This paper summarizes the particle impact tests completed at WSTF. Although there was an ignition in Test Series 4, it was determined the ignition was caused by the presence of a machining imperfection. The sum of all the test results indicates that there is no particle impact ignition hazard in the ISS ECLSS QDs. KEYWORDS: quick disconnect, high pressure, particle impact testing, stainless steel

Computational Model for Impact-Resisting Critical Thickness of High-Speed Machine Outer Protective Plate

Science.gov (United States)

Wu, Huaying; Wang, Li Zhong; Wang, Yantao; Yuan, Xiaolei

2018-05-01

The blade or surface grinding blade of the hypervelocity grinding wheel may be damaged due to too high rotation rate of the spindle of the machine and then fly out. Its speed as a projectile may severely endanger the field persons. Critical thickness model of the protective plate of the high-speed machine is studied in this paper. For easy analysis, the shapes of the possible impact objects flying from the high-speed machine are simplified as sharp-nose model, ball-nose model and flat-nose model. Whose front ending shape to represent point, line and surface contacting. Impact analysis based on J-C model is performed for the low-carbon steel plate with different thicknesses in this paper. One critical thickness computational model for the protective plate of high-speed machine is established according to the damage characteristics of the thin plate to get relation among plate thickness and mass, shape and size and impact speed of impact object. The air cannon is used for impact test. The model accuracy is validated. This model can guide identification of the thickness of single-layer outer protective plate of a high-speed machine.

Pipe-to-pipe impact tests

Energy Technology Data Exchange (ETDEWEB)

Bampton, M C.C.; Alzheimer, J M; Friley, J R; Simonen, F A

1985-11-01

Existing licensing criteria express what damage shall be assumed for various pipe sizes as a consequence of a postulated break in a high energy system. The criteria are contained in Section 3.6.2 of the Standard Review Plan, and the purpose of the program described with this paper is to evaluate the impact criteria by means of a combined experimental and analytical approach. A series of tests has been completed. Evaluation of the test showed a deficiency in the range of test parameters. These deficiencies are being remedied by a second series of tests and a more powerful impact machine. A parallel analysis capability has been developed. This capability has been used to predict the damage for the first test series. The quality of predictions has been improved by tests that establish post-crush and bending relationships. Two outputs are expected from this project: data that may, or may not, necessitate changes to the criteria after appropriate value impact evaluations and an analytic capability for rapidly evaluating the potential for pipe whip damage after a postulated break. These outputs are to be contained in a value-impact document and a program final report. (orig.).

Light-weight radioisotope heater impact tests

International Nuclear Information System (INIS)

Reimus, M.A.H.; Rinehart, G.H.; Herrera, A.

1998-01-01

The light-weight radioisotope heater unit (LWRHU) is a 238 PuO 2 -fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed 238 PuO 2 fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s

Impact Testing of Stainless Steel Materials

International Nuclear Information System (INIS)

R. K. Blandford; D. K. Morton; T. E. Rahl; S. D. Snow

2005-01-01

Stainless steels are used for the construction of numerous spent nuclear fuel or radioactive material containers that may be subjected to high strains and moderate strain rates (10 to 200 per second) during accidental drop events. Mechanical characteristics of these materials under dynamic (impact) loads in the strain rate range of concern are not well documented. The goal of the work presented in this paper was to improve understanding of moderate strain rate phenomena on these materials. Utilizing a drop-weight impact test machine and relatively large test specimens (1/2-inch thick), initial test efforts focused on the tensile behavior of specific stainless steel materials during impact loading. Impact tests of 304L and 316L stainless steel test specimens at two different strain rates, 25 per second (304L and 316L material) and 50 per second (304L material) were performed for comparison to their quasi-static tensile test properties. Elevated strain rate stress-strain curves for the two materials were determined using the impact test machine and a ''total impact energy'' approach. This approach considered the deformation energy required to strain the specimens at a given strain rate. The material data developed was then utilized in analytical simulations to validate the final elevated stress-strain curves. The procedures used during testing and the results obtained are described in this paper

Mitigation of Autoignition Due to Premixing in a Hypervelocity Flow Using Active Wall Cooling

Science.gov (United States)

Axdahl, Erik; Kumar, Ajay; Wilhite, Alan

2013-01-01

Preinjection of fuel on the forebody of an airbreathing vehicle is a proposed method to gain access to hypervelocity flight Mach numbers. However, this creates the possibility of autoignition either near the wall or in the core of the flow, thereby consuming fuel prematurely as well as increasing the amount of pressure drag on the vehicle. The computational fluid dynamics code VULCAN was used to conduct three dimensional simulations of the reacting flow in the vicinity of hydrogen injectors on a flat plate at conditions relevant to a Mach 12 notional flight vehicle forebody to determine the location where autoignition occurs. Active wall cooling strategies were formulated and simulated in response to regions of autoignition. It was found that tangential film cooling using hydrogen or helium were both able to nearly or completely eliminate wall autoignition in the flow domain of interest.

Short-duration Lensing Events: Wide-orbit Planets? Free-floating Dwarfs? Or Hypervelocity Stellar Remnants?

Science.gov (United States)

Di Stefano, Rosanne; Patel, B.; Kallivayalil, N.; Primini, F. A.

2009-01-01

Ongoing microlensing observations by OGLE and MOA regularly detect and conduct high-cadence sampling of lensing events with Einstein diameter crossing times shorter than a few days. We show that many short-duration events are likely to have been caused by planet-mass or brown-dwarf lenses. Many of these low-mass lenses are located within a kpc. Information about some individual systems can be derived through a combination of lensing, radial velocity, and transit studies. The present discovery rate is high enough that the study of short-duration events could soon become the primary channel for planet detection via microlensing. We develop a protocol for observing and modeling these events, and apply it to archived data. A small number of short events may be caused by hypervelocity (v 10^3 km/s) masses located within a kpc.

30 CFR 7.46 - Impact test.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Impact test. 7.46 Section 7.46 Mineral... MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test. (a) Test... individual cells. At the test temperature range of 65 °F -80 °F (18.3 °C-26.7 °C), apply a dynamic force of...

Charpy Impact Test on Polymeric Molded Parts

Directory of Open Access Journals (Sweden)

Alexandra Raicu

2012-09-01

Full Text Available The paper presents the Charpy impact tests on the AcrylonitrileButadiene-Styrene (ABS polymeric material parts. The Charpy impact test, also known as the Charpy V-notch test, is a standardized strain rate test which determines the amount of energy absorbed by a material during fracture. This is a typical method described in ASTM Standard D 6110. We use for testing an Instron - Dynatup equipment which have a fully integrated hardware and software package that let us capture load information at very high speed from the impact tests.

Ballistic Limit Equation for Single Wall Titanium

Science.gov (United States)

Ratliff, J. M.; Christiansen, Eric L.; Bryant, C.

2009-01-01

Hypervelocity impact tests and hydrocode simulations were used to determine the ballistic limit equation (BLE) for perforation of a titanium wall, as a function of wall thickness. Two titanium alloys were considered, and separate BLEs were derived for each. Tested wall thicknesses ranged from 0.5mm to 2.0mm. The single-wall damage equation of Cour-Palais [ref. 1] was used to analyze the Ti wall's shielding effectiveness. It was concluded that the Cour-Palais single-wall equation produced a non-conservative prediction of the ballistic limit for the Ti shield. The inaccurate prediction was not a particularly surprising result; the Cour-Palais single-wall BLE contains shield material properties as parameters, but it was formulated only from tests of different aluminum alloys. Single-wall Ti shield tests were run (thicknesses of 2.0 mm, 1.5 mm, 1.0 mm, and 0.5 mm) on Ti 15-3-3-3 material custom cut from rod stock. Hypervelocity impact (HVI) tests were used to establish the failure threshold empirically, using the additional constraint that the damage scales with impact energy, as was indicated by hydrocode simulations. The criterion for shield failure was defined as no detached spall from the shield back surface during HVI. Based on the test results, which confirmed an approximately energy-dependent shield effectiveness, the Cour-Palais equation was modified.

Two-stage light-gas magnetoplasma accelerator for hypervelocity impact simulation

International Nuclear Information System (INIS)

Khramtsov, P P; Vasetskij, V A; Makhnach, A I; Grishenko, V M; Chernik, M Yu; Shikh, I A; Doroshko, M V

2016-01-01

The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas. (paper)

Two-stage light-gas magnetoplasma accelerator for hypervelocity impact simulation

Science.gov (United States)

Khramtsov, P. P.; Vasetskij, V. A.; Makhnach, A. I.; Grishenko, V. M.; Chernik, M. Yu; Shikh, I. A.; Doroshko, M. V.

2016-11-01

The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas.

THE GALACTIC POTENTIAL AND THE ASYMMETRIC DISTRIBUTION OF HYPERVELOCITY STARS

International Nuclear Information System (INIS)

Perets, Hagai B.; Alexander, Tal; Wu Xufen; Zhao Hongsheng; Famaey, Benoit; Gentile, Gianfranco

2009-01-01

In recent years several hypervelocity stars (HVSs) have been observed in the halo of our Galaxy. Such HVSs have possibly been ejected from the Galactic center and then propagated in the Galactic potential up to their current position. The recent survey for candidate HVSs show an asymmetry in the kinematics of candidate HVSs (position and velocity vectors), where more outgoing stars than ingoing stars (i.e., positive Galactocentric velocities versus negative ones) are observed. We show that such kinematic asymmetry, which is likely due to the finite lifetime of the stars and Galactic potential structure, could be used in a novel method to probe and constrain the Galactic potential, identify the stellar type of the stars in the survey and estimate the number of HVSs. Kinematics-independent identification of the stellar types of the stars in such surveys (e.g., spectroscopic identification) could further improve these results. We find that the observed asymmetry between ingoing and outgoing stars favors specific Galactic potential models. It also implies a lower limit of ∼54 ± 8 main-sequence HVSs in the survey sample (∼>648 ± 96 in the Galaxy), assuming that all of the MS stars in the survey originate from the GC. The other stars in the survey are likely to be hot blue horizontal branch stars born in the halo rather than stars ejected from the GC.

The spatial distribution and time evolution of impact-generated magnetic fields

Science.gov (United States)

Crawford, D. A.; Schultz, P. H.

1991-01-01

The production of magnetic fields was revealed by laboratory hypervelocity impacts in easily vaporized targets. As quantified by pressure measurements, high frame-rate photography, and electrostatic probes, these impacts tend to produce large quantities of slightly ionized vapor, which is referred to as impact-generated plasma. Nonaligned electron density and temperature gradients within this plasma may lead to production of the observed magnetic fields. Past experiments were limited to measuring a single component of the impact-generated magnetic fields at only a few locations about the developing impact crater and consequently gave little information about the field production mechanism. To understand this mechanism, the techniques were extended to map the three components of the magnetic field both in space and time. By conducting many otherwise identical experiments with arrayed magnetic detectors, a preliminary 3-D picture was produced of impact-generated magnetic fields as they develop through time.

Hypervelocity dust particle impacts observed by the Giotto Magnetometer and Plasma Experiments

OpenAIRE

Neubauer, F. M.; Glassmeier, K. H.; Coates, A. J.; Goldstein, R.; Acuña, M. H.; Musmann, G.

1990-01-01

We report thirteen very short events in the magnetic field of the inner magnetic pile‐up region of comet Halley observed by the Giotto magnetometer experiment together with simultaneous plasma data obtained by the Johnstone plasma analyzer and the ion mass spectrometer experiments. The events are due to dust impacts in the milligram range on the spacecraft at the relative velocity between the cemetery dust and the spacecraft of 68 km/sec. They are generally consistent with dust impact events ...

Tests of the Giant Impact Hypothesis

Science.gov (United States)

Jones, J. H.

1998-01-01

The giant impact hypothesis has gained popularity as a means of explaining a volatile-depleted Moon that still has a chemical affinity to the Earth. As Taylor's Axiom decrees, the best models of lunar origin are testable, but this is difficult with the giant impact model. The energy associated with the impact would be sufficient to totally melt and partially vaporize the Earth. And this means that there should he no geological vestige of Barber times. Accordingly, it is important to devise tests that may be used to evaluate the giant impact hypothesis. Three such tests are discussed here. None of these is supportive of the giant impact model, but neither do they disprove it.

Chandra Observations of the Deep Impact Encounter with Comet 9P/Tempel 1

Science.gov (United States)

Lisse, C. M.; Christian, D. J.; Dennerl, K.; Wolk, S. J.; Bodewits, D.; Combi, M. R.; Hoekstra, R.; Makinen, T.; Schultz, P. H.; Weaver, H. A.

2005-08-01

On July 4, 2005 NASA's discovery mission Deep Impact (hereafter DI) will send a 375 kg impactor into the nucleus of comet 9P/Tempel 1 at 10.2 km/s relative velocity. In the x-ray, the DI experiment allows for a controlled test of the charge exchange (CXE) emission mechanism that drives cometary x-ray emission (Lisse et al. 2001, Kharchenko and Dalgarno 2001, Krasnopolsky et al.2002). Previous ROSAT and Chandra observations studied cometary x-ray emission as the solar wind changed but the cometary emission remained constant. Here, at a precise time, a fresh amount of neutral material will be injected into a finite volume of the extended atmosphere, or coma, of the comet. This new material will directly increase the emission measure for the comet, passing from the collisionally thick to the collisionally thin regions of emission over the course of days. The DI experiment also allows for a direct search for prompt x-rays created by hyper-velocity impact processes, such as was seen by ROSAT during the impact of the K-fragment of comet D/Shoemaker-Levy 9 on Jupiter (Waite et al. 1995). We report here on the first results of of the Chandra observations of the Deep Impact encounter.

High rate loading tests and impact tests of concrete and reinforcement

International Nuclear Information System (INIS)

Takeda, J.I.; Tachikawa, H.; Fujimoto, K.

1982-01-01

The responses of reinforced concrete structural members and structures subjected to impact or impulsive loadings are affected by the behavior of constituent concrete and reinforcement which are the synthesis of the rate effects and the contribution of propagating stress waves of them. The rate effects and the contribution of stress waves do not have the same tendency in the variation of magnitude of them with speed of impact or impulsive loadings. Therefore the rate effects, mentioned above, should be obtained by the tests minimized the effect of stress waves (high rate loading test). This paper deals with the testing techniques with high rate loadings and impact, and also reports the main results of these tests. (orig.) [de

Impact testing of transportation-flasks

International Nuclear Information System (INIS)

Neilson, A.J.

1985-07-01

The literature describing flask testing is reviewed and it is concluded that, even though there are numerous references to instrumented impact testing of flasks, there remains a need for a collection of data from carefully constructed and fully instrumented model tests for thorough validation of analytical tools. (author)

Impact Testing for Materials Science at NASA - MSFC

Science.gov (United States)

Sikapizye, Mitch

2010-01-01

The Impact Testing Facility (ITF) at NASA - Marshall Space Flight Center is host to different types of guns used to study the effects of high velocity impacts. The testing facility has been and continues to be utilized for all NASA missions where impact testing is essential. The Facility has also performed tests for the Department of Defense, other corporations, as well as universities across the nation. Current capabilities provided by Marshall include ballistic guns, light gas guns, exploding wire gun, and the Hydrometeor Impact Gun. A new plasma gun has also been developed which would be able to propel particles at velocities of 20km/s. This report includes some of the guns used for impact testing at NASA Marshall and their capabilities.

Effects of Friction and Plastic Deformation in Shock-Comminuted Damaged Rocks on Impact Heating

Science.gov (United States)

Kurosawa, Kosuke; Genda, Hidenori

2018-01-01

Hypervelocity impacts cause significant heating of planetary bodies. Such events are recorded by a reset of 40Ar-36Ar ages and/or impact melts. Here we investigate the influence of friction and plastic deformation in shock-generated comminuted rocks on the degree of impact heating using the iSALE shock-physics code. We demonstrate that conversion from kinetic to internal energy in the targets with strength occurs during pressure release, and additional heating becomes significant for low-velocity impacts (projectile mass to temperatures for the onset of Ar loss and melting from 8 and 10 km s-1, respectively, for strengthless rocks to 2 and 6 km s-1 for typical rocks. Our results suggest that the impact conditions required to produce the unique features caused by impact heating span a much wider range than previously thought.

Full-scale Tornado-missile impact tests

International Nuclear Information System (INIS)

1976-04-01

Initial tests with four types of hypothetical tornado-borne missiles impacting reinforced concrete panels have been completed. Panel thicknesses are typical of walls in nuclear power facilities. In the seven tests, the missiles were rocket propelled to velocities currently postulated as being attainable by debris in tornadoes. The objective of the 18-test program is to ascertain the vulnerability of test panels to penetration and backface scabbing. The four missile types being tested are: a 1500-pound 35-foot long utility pole, an 8-pound 1-inch Grade 60 reinforcing bar, a 78-pound 3-inch Schedule 40 pipe, and a 743-pound 12-inch Schedule 40 pipe. The test panels are 12, 18, and 24 inches thick with 15 by 15 foot free spans. They were constructed to current minimum ACI standards: 3000 psi design strength (actual strength about 3600 psi) and 0.2 percent reinforcing steel area each way, each face (actual area is about 0.27 percent with bars on 12-inch centers). The 12-inch pipe has been identified as the critical missile for design of nuclear facility walls under currently specified impact conditions. The utility poles splintered upon impact causing virtually no impact damage, and the 3-inch pipe and 1-inch rebar were comparatively ineffectual because of their light weight

Optical transmission for the James Webb Space Telescope

Science.gov (United States)

Lightsey, Paul A.; Gallagher, Benjamin B.; Nickles, Neal; Copp, Tracy

2012-09-01

The fabrication and coating of the mirrors for the James Webb Space Telescope has been completed. The spectral reflectivity of the protected gold coated beryllium mirrors has been measured. The predicted end-of-life transmission through the telescope builds from these values. The additional phenomena that have been analyzed are contamination effects and effects of the environment for the JWST operation about the Earth-Sun L2 Lagrange libration point. The L2 environment analysis has been based on radiation testing of mirror samples and hypervelocity testing to assess the micrometeoroid impact effects. The mirror showed no change in reflectance over the VIS-SWIR wavelengths after exposure to 6-9 Grad (Si) that simulated 6 years orbiting the L2 Lagrange point. The effects of hypervelocity particle impacts on the mirrors from test data has been extrapolated to the to the anticipated flux characteristics for micrometeoroids at the L2 environment. The results show that the micrometeoroid effects are orders of magnitude below the particulate contamination effects. The final end-of-life transmission for the mirrors including all of these phenomena will meet the performance requirements for JWST.

Understanding protocol performance: impact of test performance.

Science.gov (United States)

Turner, Robert G

2013-01-01

This is the second of two articles that examine the factors that determine protocol performance. The objective of these articles is to provide a general understanding of protocol performance that can be used to estimate performance, establish limits on performance, decide if a protocol is justified, and ultimately select a protocol. The first article was concerned with protocol criterion and test correlation. It demonstrated the advantages and disadvantages of different criterion when all tests had the same performance. It also examined the impact of increasing test correlation on protocol performance and the characteristics of the different criteria. To examine the impact on protocol performance when individual tests in a protocol have different performance. This is evaluated for different criteria and test correlations. The results of the two articles are combined and summarized. A mathematical model is used to calculate protocol performance for different protocol criteria and test correlations when there are small to large variations in the performance of individual tests in the protocol. The performance of the individual tests that make up a protocol has a significant impact on the performance of the protocol. As expected, the better the performance of the individual tests, the better the performance of the protocol. Many of the characteristics of the different criteria are relatively independent of the variation in the performance of the individual tests. However, increasing test variation degrades some criteria advantages and causes a new disadvantage to appear. This negative impact increases as test variation increases and as more tests are added to the protocol. Best protocol performance is obtained when individual tests are uncorrelated and have the same performance. In general, the greater the variation in the performance of tests in the protocol, the more detrimental this variation is to protocol performance. Since this negative impact is increased as

Examination of Relationship Between Photonic Signatures and Fracture Strength of Fused Silica Used in Orbiter Windows

Science.gov (United States)

Yost, William T.; Cramer, K. Elliott; Estes, Linda R.; Salem, Jonathan A.; Lankford, James, Jr.; Lesniak, Jon

2011-01-01

A commercially available grey-field polariscope (GFP) instrument for photoelastic examination is used to assess impact damage inflicted upon the outermost pane of the orbiter windows. Four categories of damage: hyper-velocity impacts that occur during space-flight (HVI); hypervelocity impacts artificially made at the Hypervelocity Impact Technology Facility (HIT-F); impacts made by larger objects falling onto the pane surface to simulate dropped items on the window during service/storage of vehicle (Bruises); and light scratches from dull objects designed to mimic those that might occur by dragging a dull object across the glass surface (Chatter Checks) are examined. The damage sites are cored from fused silica window carcasses, examined with the GFP and other methodologies, and broken using the ASTM Standard C1499-09 to measure the fracture strength. A correlation is made between the fracture strength and damage-site measurements including geometrical measurements and GFP measurements of photoelastic retardation (stress patterns) surrounding the damage sites. An analytical damage model to predict fracture strength from photoelastic retardation measurements is presented and compared with experimental results.

Dynamic tests on metallic impact limiters

International Nuclear Information System (INIS)

Sagartz, M.J.

1978-01-01

Three different types of metallic impact limiters were tested; plain fins, laterally stiffened fins and tubes whose axes were aligned with the direction of impact. All specimens were made of 304 stainless steel and were annealed before testing. A heavy steel drop table of variable mass and moving at about 13.4 m/s (44 ft/s) was used to impact the specimens which were mounted on a stationary base. Impact velocity, drop table acceleration vs. time and force vs. time were measured on each test and were used to calculate the energy absorbed by the impact limiters. Results showed that the peak stress that a plain fin can transmit to the cask body can be several times the static yield stress of the fin. Also as buckling proceeds the load in a plain fin drops significantly and the rate at which it absorbs energy falls off dramatically, making the fin a rather inefficient energy absorber overall. The laterally stiffened fin and the cylinders did not exhibit this rapid decrease in load-carrying capacity with deformation and hence were able to absorb relatively more energy per unit volume of material

Extra-regulatory impact tests and analyses of the structural evaluation test unit

International Nuclear Information System (INIS)

Ludwigsen, J.S.; Ammerman, D.J.

1995-01-01

The structural evaluation test unit is roughly equivalent to a 1/3 scale model of a high level waste rail cask. The test unit was designed to just meet the requirements of NRC Regulatory Guide 7.6 when subjected to a 9 m (30 ft) free drop resulting in an impact velocity of 13.4 m/s (30 mph) onto an unyielding target in the end-on orientation. The test unit was then subjected to impacts with higher velocities to determine the amount of built-in conservatism in this design approach. Test impacts of 13.4, 20.1 and 26.8 m/s (30, 45, and 60 mph) were performed. This paper will describe the design, testing, and comparison of measured strains and deformations to the equivalent analytical predictions

Alpha Fuels Environmental Test Facility impact gun

International Nuclear Information System (INIS)

Anderson, C.G.

1978-01-01

The Alpha Fuels Environmental Test Facility (AFETF) impact gun is a unique tool for impact testing 238 PuO 2 -fueled heat sources of up to 178-mm dia at velocities to 300 m/s. An environmentally-sealed vacuum chamber at the muzzle of the gun allows preheating of the projectile to 1,000 0 C. Immediately prior to impact, the heat source projectile is completely sealed in a vacuum-tight catching container to prevent escape of its radioactive contents should rupture occur. The impact velocity delivered by this gas-powered gun can be regulated to within +-2%

Innovative ICF scheme-impact fast ignition

International Nuclear Information System (INIS)

Murakami, M.; Nagatomo, H.; Sakaiya, T.; Karasik, M.; Gardner, J.; Bates, J.

2007-01-01

A totally new ignition scheme for ICF, impact fast ignition (IFI), is proposed [1], in which the compressed DT main fuel is to be ignited by impact collision of another fraction of separately imploded DT fuel, which is accelerated in the hollow conical target. Two-dimensional hydrodynamic simulation results in full geometry are presented, in which some key physical parameters for the impact shell dynamics such as 10 8 cm/s of the implosion velocity, 200- 300 g/cm 3 of the compressed density, and the converted temperature beyond 5 keV are demonstrated. As the first step toward the proof-of-principle of IFI, we have conducted preliminary experiments under the operation of GEKKO XII/HYPER laser system to achieve a hyper-velocity of the order of 108 cm/s. As a result we have observed a highest velocity, 6.5 x 10 7 cm/s, ever achieved. Furthermore, we have also done the first integrated experiments using the target and observed substantial amount of neutron yields. Reference: [1] M. Murakami and Nagatomo, Nucl. Instrum. Meth. Phys. Res. A 544(2005) 67

Hypervelocity dust particle impacts observed by the Giotto magnetometer and plasma experiments

Science.gov (United States)

Neubauer, F. M.; Glassmeier, K.-H.; Coates, A. J.; Goldstein, R.; Acuna, M. H.

1990-01-01

This paper describes 13 very short events in the magnetic field of the inner magnetic pile-up region of Comet Halley observed by the Giotto magnetometer experiment together with simultaneous plasma data obtained by the Johnstone plasma analyzer and the ion mass spectrometer experiments. The events are due to dust impacts in the milligram range on the spacecraft at the relative velocity between the cometary dust and the spacecraft of 68 km/sec. They are generally consistent with dust impact events derived from spacecraft attitude perturbations by the Giotto camera. Their characteristic shape generally involves a sudden decrease in magnetic-field magnitude, a subsequent overshoot beyond initial field values, and an asymptotic approach to the initial field (somewhat reminiscent of the magnetic-field signature after the AMPTE releases in the solar wind). These observations give a new way of analyzing ultra-fast dust particles incident on a spacecraft.

The importance of high injection velocity to reduce plasma armature growth and drag in hypervelocity railguns

International Nuclear Information System (INIS)

Hawke, R.S.; Dixon, W.R.; Kang, S.W.; McCallen, R.C.; Susoeff, A.R.; Asay, J.R.; Shaninpoor, M.

1987-01-01

Plasmas are required to serve as armature in hypervelocity railguns. Typically, the plasmas are at temperatures of about 20-30,000 K and result in a high heat flux on the barrel wall. Slow moving plasmas radiate heat and melt the launcher wall causing it to ablate and resulting in a growth of the armature mass and length. As the velocity increases, the more massive and longer armature will result in greater viscous drag and ultimately limit the maximum achievable velocity. Several possible means of reducing the armature growth are possible. This paper discusses two of them, use of heat resistant barrel materials, and reduction of wall heating by reduction of exposure time through use of a high initial velocity. A summary of experimentally based, material ablation resistance calculations is presented. Second, the benefit of high injection velocity is evaluated. Finally, a joint SNLA and LLNL railgun research project based on the above considerations are described

Solid propellant impact tests

International Nuclear Information System (INIS)

Snow, E.C.

1976-03-01

Future space missions, as in the past, call for the continued use of radioisotopes as heat sources for thermoelectric power generators. In an effort to minimize the risk of radioactive contamination of the environment, a complete safety analysis of each such system is necessary. As a part of these analyses, the effects on such a system of a solid propellant fire environment resulting from a catastrophic launch pad abort must be considered. Several impact tests were conducted in which either a simulant MHW-FSA or a steel ball was dropped on the cold, unignited or the hot, burning surface of a block of UTP-3001 solid propellant. The rebound velocities were measured for both surface conditions of the propellant. The resulting coefficient of restitution, determined as the ratio of the components of the impact and rebound velocities perpendicular to the impact surface of the propellant, were not very dependent on whether the surface was cold or hot at the time of impact

Sand Impact Tests of a Half-Scale Crew Module Boilerplate Test Article

Science.gov (United States)

Vassilakos, Gregory J.; Hardy, Robin C.

2012-01-01

Although the Orion Multi-Purpose Crew Vehicle (MPCV) is being designed primarily for water landings, a further investigation of launch abort scenarios reveals the possibility of an onshore landing at Kennedy Space Center (KSC). To gather data for correlation against simulations of beach landing impacts, a series of sand impact tests were conducted at NASA Langley Research Center (LaRC). Both vertical drop tests and swing tests with combined vertical and horizontal velocity were performed onto beds of common construction-grade sand using a geometrically scaled crew module boilerplate test article. The tests were simulated using the explicit, nonlinear, transient dynamic finite element code LS-DYNA. The material models for the sand utilized in the simulations were based on tests of sand specimens. Although the LSDYNA models provided reasonable predictions for peak accelerations, they were not always able to track the response through the duration of the impact. Further improvements to the material model used for the sand were identified based on results from the sand specimen tests.

An artificial neural network to discover hypervelocity stars: candidates in Gaia DR1/TGAS

Science.gov (United States)

Marchetti, T.; Rossi, E. M.; Kordopatis, G.; Brown, A. G. A.; Rimoldi, A.; Starkenburg, E.; Youakim, K.; Ashley, R.

2017-09-01

The paucity of hypervelocity stars (HVSs) known to date has severely hampered their potential to investigate the stellar population of the Galactic Centre and the Galactic potential. The first Gaia data release (DR1, 2016 September 14) gives an opportunity to increase the current sample. The challenge is the disparity between the expected number of HVSs and that of bound background stars. We have applied a novel data mining algorithm based on machine learning techniques, an artificial neural network, to the Tycho-Gaia astrometric solution catalogue. With no pre-selection of data, we could exclude immediately ˜99 per cent of the stars in the catalogue and find 80 candidates with more than 90 per cent predicted probability to be HVSs, based only on their position, proper motions and parallax. We have cross-checked our findings with other spectroscopic surveys, determining radial velocities for 30 and spectroscopic distances for five candidates. In addition, follow-up observations have been carried out at the Isaac Newton Telescope for 22 stars, for which we obtained radial velocities and distance estimates. We discover 14 stars with a total velocity in the Galactic rest frame >400 km s-1, and five of these have a probability of >50 per cent of being unbound from the Milky Way. Tracing back their orbits in different Galactic potential models, we find one possible unbound HVS with v ˜ 520 km s-1, five bound HVSs and, notably, five runaway stars with median velocity between 400 and 780 km s-1. At the moment, uncertainties in the distance estimates and ages are too large to confirm the nature of our candidates by narrowing down their ejection location, and we wait for future Gaia releases to validate the quality of our sample. This test successfully demonstrates the feasibility of our new data-mining routine.

Hypervelocity dust particle impacts observed by the Giotto magnetometer and plasma experiments

International Nuclear Information System (INIS)

Neubauer, F.M.; Glassmeier, K.H.; Goldstein, R.; Acuna, M.H.; Musmann, G.; Coates, A.J.

1990-01-01

The authors report thirteen very short events in the magnetic field of the inner magnetic pile-up region of comet Halley observed by the Giotto magnetometer experiment together with simultaneous plasma data obtained by the Johnstone plasma analyzer and the ion mass spectrometer experiments. The events are due to dust impacts in the milligram range on the spacecraft at the relative velocity between the cometary dust and the spacecraft of 68 km/sec. They are generally consistent with dust impact events derived from spacecraft attitude perturbations by the Giotto camera [Curdt and Keller, private communication]. Their characteristic shape generally involves a sudden decrease in magnetic field magnitude, a subsequent overshoot beyond initial field values and an asymptotic approach to the initial field somewhat reminiscent of the magnetic field signature after the AMPTE releases in the solar wind. These observations give a new way of analyzing ultra-fast dust particles incident on a spacecraft

Numerical simulation of small scale soft impact tests

International Nuclear Information System (INIS)

Varpasuo, Pentti

2008-01-01

This paper describes the small scale soft missile impact tests. The purpose of the test program is to provide data for the calibration of the numerical simulation models for impact simulation. In the experiments, both dry and fluid filled missiles are used. The tests with fluid filled missiles investigate the release speed and the droplet size of the fluid release. This data is important in quantifying the fire hazard of flammable liquid after the release. The spray release velocity and droplet size are also input data for analytical and numerical simulation of the liquid spread in the impact. The behaviour of the impact target is the second investigative goal of the test program. The response of reinforced and pre-stressed concrete walls is studied with the aid of displacement and strain monitoring. (authors)

Impact radiative fusion concept

International Nuclear Information System (INIS)

Yabe, Takashi; Mochizuki, Takayasu.

1983-01-01

This letter proposes a new, fascinating ICF scheme. The scheme employs the soft x-ray production by hypervelocity projectiles. The soft x-ray of 10 13 W/cm 2 and 10 nsec duration, which is focusable onto a small sized pellet, can be efficiently produced. (author)

Structural Behavior Under Precision Impact Tests

Science.gov (United States)

1996-08-01

ASPECTS OF IMPACT TESTING The problem of impact between two bodies has been studied extensively (for example, Eibl 1987, Feyerabend 1988, Krauthammer...Concrete for Hazard Protection, Edinburgh, Scotland, pp. 175-186. Feyerabend , M., 1988, "Der harte Querstoss auf Stützen aus Stahl und Stahlbeton

Magnetic linear accelerator (MAGLAC) for hypervelocity acceleration in impact fusion (IF)

International Nuclear Information System (INIS)

Chen, K.W.

1980-01-01

This paper presents considerations on the design of a magnetic linear accelerator suitable as driver for impact fusion. We argue that the proposed approach offers an attractive option to accelerate macroscopic matter to centiluminal velocity suitable for fusion applications. The design goal is to attain a velocity approaching 200 km/sec. Recent results in suitable target design suggest that a velocity in the range of 40-100 km/sec might be sufficient to include fusion. An accelerator in this velocity range can be constructed with current-day technology. We present both design and practical engineering considerations. Future work are outlined and recommended. (orig.)

Laser Prevention of Earth Impact Disasters

Science.gov (United States)

Campbell, Jonathan W.; Howell, Joe (Technical Monitor)

2002-01-01

Today we are seeing the geological data base constantly expanding as new evidence from past impacts with the Earth are discovered and investigated. It is now commonly believed that a hypervelocity impact occurring approximately 65 million years ago in the Yucatan Peninsula area was the disaster responsible for the extinction of almost 70% of the species of life on Earth including of course the dinosaurs. What is sobering is that we believe now that this was just one of several such disasters and that some of the others caused extinctions to even a greater extent. Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most important problem facing human civilization. While there are many global problems facing our planet including overpopulation, pollution, disease, and deforestation; none of these offer the potential of rapid, total extinction. Rapid is the operative word here in that many of the global problems we face may indeed, if not sufficiently addressed, pose a similar long-term threat. However, with the impact threat, a single, almost unpredictable event could lead to a chain reaction of disasters that would end everything mankind has worked to achieve over the centuries. Our chances of being hit are greater than our chance of winning the lottery. We now believe that while there are only about 2000-earth orbit crossing rocks great than 1 kilometer in diameter, there may be as many as 100,000 rocks in the 100 m size range. The 1 kilometer rocks are difficult to detect and even harder to track. The 100 m class ones are almost impossible to find with today's technology. Can anything be done about this fundamental existence question facing us? The answer is a resounding yes. By using an intelligent combination of Earth and space based sensors coupled with high-energy laser stations in orbit, we can deflect rocks from striking the Earth. This is accomplished by irradiating the surface of the rock with sufficiently intense

Impact test for solid waste forms

International Nuclear Information System (INIS)

Wallace, R.M.; Kelley, J.A.

1976-03-01

Samples of concretes and glasses being considered for incorporation of radioactive waste sludge were subjected to impact tests to determine the relationship between the energy of the impact and the resulting increase in surface area of the damaged sample. Test results indicate that the increased surface area per unit of energy input for glass waste forms is less by a factor of about three than that for concretes containing 40 wt percent simulated sludge (average values of 9.6 cm 2 /Joule and 24.7 cm 2 /Joule for glass and concrete, respectively)

Permeability After Impact Testing of Composite Laminates

Science.gov (United States)

Nettles, Alan T.

2003-01-01

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

Dimensional analysis and extended hydrodynamic theory applied to long-rod penetration of ceramics

Directory of Open Access Journals (Sweden)

J.D. Clayton

2016-08-01

Full Text Available Principles of dimensional analysis are applied in a new interpretation of penetration of ceramic targets subjected to hypervelocity impact. The analysis results in a power series representation – in terms of inverse velocity – of normalized depth of penetration that reduces to the hydrodynamic solution at high impact velocities. Specifically considered are test data from four literature sources involving penetration of confined thick ceramic targets by tungsten long rod projectiles. The ceramics are AD-995 alumina, aluminum nitride, silicon carbide, and boron carbide. Test data can be accurately represented by the linear form of the power series, whereby the same value of a single fitting parameter applies remarkably well for all four ceramics. Comparison of the present model with others in the literature (e.g., Tate's theory demonstrates a target resistance stress that depends on impact velocity, linearly in the limiting case. Comparison of the present analysis with recent research involving penetration of thin ceramic tiles at lower typical impact velocities confirms the importance of target properties related to fracture and shear strength at the Hugoniot Elastic Limit (HEL only in the latter. In contrast, in the former (i.e., hypervelocity and thick target experiments, the current analysis demonstrates dominant dependence of penetration depth only by target mass density. Such comparisons suggest transitions from microstructure-controlled to density-controlled penetration resistance with increasing impact velocity and ceramic target thickness.

Test requirements of locomotive fuel tank blunt impact tests

Science.gov (United States)

2013-10-15

The Federal Railroad Administrations Office of Research : and Development is conducting research into passenger : locomotive fuel tank crashworthiness. A series of impact tests : are planned to measure fuel tank deformation under two types : of dy...

Development of a capacitor powered rail gun for hypervelocity impact studies

International Nuclear Information System (INIS)

Shrader, J.E.

1983-01-01

Boeing has built and tested several rail gun designs using two different capacitor banks as power sources. For each design, the muzzle velocity predicted with the Boeing Electromagnetic Gun code (BEMG) matched the measured muzzle velocity within 5%, providing gas sealing between the rails and the dielectric of the barrel was maintained. This did not validate the model, but gave reasonable confidence in it. Using the BEMG model, a parametric study was conducted to determine the sensitivity of muzzle velocities between 2 and 5 km/s to the input variables. A practical point design was assumed, and then each parameter individually varied while the others were held constant. The point design assumed an initial velocity of 0.5 km/s and an inductance per unit length (L') of 0.8 x 10 -6 H/m. Other parameters were similar to the earlier designs. The earlier designs tested had no initial velocity, and an L' of 0.3 x 10 6 H/m. A gas gun was assumed to produce the initial velocity, and resulted in only modest increases in muzzle velocity. However, it eliminated a separate make switch, since a foil across the back of the projectile becomes a make switch, and it is expected to substantially reduce rail erosion near the breech of the gun. Rail erosion was a significant problem for repeated firings in earlier designs. The parametric study showed that for the velocities of interest, increasing L' was the single best way to improve gun performance. In a practical gun, this will be achieved by making a two turn barrel, rather than a single turn barrel. The results of this study will be used to design, build and test a small gun (about 9 mm bore) using a 150 kJ capacitor bank as a power source. Using the experience gained with this gun, a large gun (about 20 mm bore) will be designed, built and tested using a 1.3 MJ capacitor bank

Space Environmental Effects Testing Capability at the Marshall Space Flight Center

Science.gov (United States)

DeWittBurns, H.; Craven, Paul; Finckenor, Miria; Nehls, Mary; Schneider, Todd; Vaughn, Jason

2012-01-01

Understanding the effects of the space environment on materials and systems is fundamental and essential for mission success. If not properly understood and designed for, the effects of the environment can lead to degradation of materials, reduction of functional lifetime, and system failure. In response to this need, the Marshall Space Flight Center has developed world class Space Environmental Effects (SEE) expertise and test facilities to simulate the space environment. Capabilities include multiple unique test systems comprising the most complete SEE testing capability available. These test capabilities include charged particle radiation (electrons, protons, ions), ultraviolet radiation (UV), vacuum ultraviolet radiation (VUV), atomic oxygen, plasma effects, space craft charging, lunar surface and planetary effects, vacuum effects, and hypervelocity impacts as well as the combination of these capabilities. In addition to the uniqueness of the individual test capabilities, MSFC is the only NASA facility where the effects of the different space environments can be tested in one location. Combined with additional analytical capabilities for pre- and post-test evaluation, MSFC is a one-stop shop for materials testing and analysis. The SEE testing and analysis are performed by a team of award winning experts nationally recognized for their contributions in the study of the effects of the space environment on materials and systems. With this broad expertise in space environmental effects and the variety of test systems and equipment available, MSFC is able to customize tests with a demonstrated ability to rapidly adapt and reconfigure systems to meet customers needs. Extensive flight experiment experience bolsters this simulation and analysis capability with a comprehensive understanding of space environmental effects.

Instrumented impact testing machine with reduced specimen oscillation effects

International Nuclear Information System (INIS)

Rintamaa, R.; Rahka, K.; Wallin, K.

1984-07-01

Owing to small and inexpensive specimens the Charpy impact test is widely used in quality control and alloy development. Limitations in power reactor survellance capsules it is also widely used for safety analysis purposes. Instrumenting the tup and computerizing data acquisition, makes dynamic fracture mechanics data measurement possible and convenient. However, the dynamic effects (inertia forces, specimen oscillations) in the impact test cause inaccuracies in the recorded load-time diagram and hence diminish the reliability of the calculated dynamic fracture mechanics parameters. To decrease inaccuracies a new pendulum type of instrumented impact test apparatus has been developed and constructed in the Metals Laboratory of the Technical Research Centre of Finland. This tester is based on a new principle involving inverted test geometry. The purpose of the geometry inversion is to reduce inertia load and specimen oscillation effects. Further, the new impact tester has some other novel features: e.g. the available initia impact energy is about double compared to the conventional standard (300 J) impact tester allowing the use of larger (10 x 20 x 110 mm) bend specimens than normal Charpy specimens. Also, the rotation asix in the three point bending is nearly stationary making COD-measurements possible. An experimental test series is described in which the inertia effects and specimen oscillations are compared in the conventional and new impact tester utilizing Charpy V-notch specimens. Comparison of the two test geometries is also made with the aid of an analytical model using finite element method (FEM) analysis. (author)

Hypervelocity Impact: Proceedings of the 1992 Symposium Held in Austin, Texas on 17-19 November 1992

Science.gov (United States)

1993-10-01

hardening of the impact surface. The metals, copper and aluminum, are both represented in a wealth of impact data obtained in macroscopic impacts at...both theoretical and computational modeling of deformation physics. We have obtained a wealth of impact data in the form of cratered targets, many still...Lawrence Livermore National Laboratory Nellis, William J. Lawrence Livermore Naitonal Laboratory Normandia, Dr. Michael J. Kaman Sciences Corporation

A 2 MV Van de Graaff accelerator as a tool for planetary and impact physics research

International Nuclear Information System (INIS)

Mocker, Anna; Bugiel, Sebastian; Srama, Ralf; Auer, Siegfried; Baust, Guenter; Matt, Guenter; Otto, Katharina; Colette, Andrew; Drake, Keith; Kempf, Sascha; Munsat, Tobin; Shu, Anthony; Sternovsky, Zoltan; Fiege, Katherina; Postberg, Frank; Gruen, Eberhard; Heckmann, Frieder; Helfert, Stefan; Hillier, Jonathan; Mellert, Tobias

2011-01-01

Investigating the dynamical and physical properties of cosmic dust can reveal a great deal of information about both the dust and its many sources. Over recent years, several spacecraft (e.g., Cassini, Stardust, Galileo, and Ulysses) have successfully characterised interstellar, interplanetary, and circumplanetary dust using a variety of techniques, including in situ analyses and sample return. Charge, mass, and velocity measurements of the dust are performed either directly (induced charge signals) or indirectly (mass and velocity from impact ionisation signals or crater morphology) and constrain the dynamical parameters of the dust grains. Dust compositional information may be obtained via either time-of-flight mass spectrometry of the impact plasma or direct sample return. The accurate and reliable interpretation of collected spacecraft data requires a comprehensive programme of terrestrial instrument calibration. This process involves accelerating suitable solar system analogue dust particles to hypervelocity speeds in the laboratory, an activity performed at the Max Planck Institut fuer Kernphysik in Heidelberg, Germany. Here, a 2 MV Van de Graaff accelerator electrostatically accelerates charged micron and submicron-sized dust particles to speeds up to 80 km s -1 . Recent advances in dust production and processing have allowed solar system analogue dust particles (silicates and other minerals) to be coated with a thin conductive shell, enabling them to be charged and accelerated. Refinements and upgrades to the beam line instrumentation and electronics now allow for the reliable selection of particles at velocities of 1-80 km s -1 and with diameters of between 0.05 μm and 5 μm. This ability to select particles for subsequent impact studies based on their charges, masses, or velocities is provided by a particle selection unit (PSU). The PSU contains a field programmable gate array, capable of monitoring in real time the particles' speeds and charges, and is

Frontiers in Anisotropic Shock-Wave Modeling

Science.gov (United States)

2012-02-01

Epoxy IFPT simulated and experimental back surface velocities for 572, 788, and 1015 m/s. The experimental data Kevlar / Epoxy materials recovered after...model development for the Nextel and Kevlar / Epoxy materials subject to hypervelocity impact. They also performed the experimental inverse flyer test...IFPT) for Nextel and Kevlar / Epoxy . Their models were to be macro-mechanically based and suitable for implementation into a hydrocode coupled with EOS

Further Insight on the Hypervelocity White Dwarf, LP 40–365 (GD 492): A Nearby Emissary from a Single-degenerate Type Ia Supernova

Science.gov (United States)

Raddi, R.; Hollands, M. A.; Koester, D.; Gänsicke, B. T.; Gentile Fusillo, N. P.; Hermes, J. J.; Townsley, D. M.

2018-05-01

The recently discovered hypervelocity white dwarf LP 40‑365 (aka GD 492) has been suggested as the outcome of the failed disruption of a white dwarf in a subluminous Type Ia supernova (SN Ia). We present new observations confirming GD 492 as a single star with unique spectral features. Our spectroscopic analysis suggests that a helium-dominated atmosphere, with ≃33% neon and 2% oxygen by mass, can reproduce most of the observed properties of this highly unusual star. Although our atmospheric model contrasts with the previous analysis in terms of dominant atmospheric species, we confirm that the atmosphere of GD 492 is strongly hydrogen deficient, {log}({{H}}/{He})Ia event over alternative scenarios.

Lunar Impact Flash Locations from NASA's Lunar Impact Monitoring Program

Science.gov (United States)

Moser, D. E.; Suggs, R. M.; Kupferschmidt, L.; Feldman, J.

2015-01-01

Meteoroids are small, natural bodies traveling through space, fragments from comets, asteroids, and impact debris from planets. Unlike the Earth, which has an atmosphere that slows, ablates, and disintegrates most meteoroids before they reach the ground, the Moon has little-to-no atmosphere to prevent meteoroids from impacting the lunar surface. Upon impact, the meteoroid's kinetic energy is partitioned into crater excavation, seismic wave production, and the generation of a debris plume. A flash of light associated with the plume is detectable by instruments on Earth. Following the initial observation of a probable Taurid impact flash on the Moon in November 2005,1 the NASA Meteoroid Environment Office (MEO) began a routine monitoring program to observe the Moon for meteoroid impact flashes in early 2006, resulting in the observation of over 330 impacts to date. The main objective of the MEO is to characterize the meteoroid environment for application to spacecraft engineering and operations. The Lunar Impact Monitoring Program provides information about the meteoroid flux in near-Earth space in a size range-tens of grams to a few kilograms-difficult to measure with statistical significance by other means. A bright impact flash detected by the program in March 2013 brought into focus the importance of determining the impact flash location. Prior to this time, the location was estimated to the nearest half-degree by visually comparing the impact imagery to maps of the Moon. Better accuracy was not needed because meteoroid flux calculations did not require high-accuracy impact locations. But such a bright event was thought to have produced a fresh crater detectable from lunar orbit by the NASA spacecraft Lunar Reconnaissance Orbiter (LRO). The idea of linking the observation of an impact flash with its crater was an appealing one, as it would validate NASA photometric calculations and crater scaling laws developed from hypervelocity gun testing. This idea was

INTER LABORATORY COMBAT HELMET BLUNT IMPACT TEST METHOD COMPARISON

Science.gov (United States)

2018-03-26

data by Instrumentation for Impact  Test , SAE standard J211‐1 [4]. Although the entire curve is collected, the interest of this  project  team  solely...HELMET BLUNT IMPACT TEST METHOD COMPARISON by Tony J. Kayhart Charles A. Hewitt and Jonathan Cyganik March 2018 Final...INTER-LABORATORY COMBAT HELMET BLUNT IMPACT TEST METHOD COMPARISON 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR

End-on radioisotope thermoelectric generator impact tests

International Nuclear Information System (INIS)

Reimus, M.A.H.; Hhinckley, J.E.

1997-01-01

The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of [sup 238]Pu decay to an array of thermoelectric elements in a radioisotope thermoelectric generator (RTG). The modular GPHS design was developed to address both survivability during launch abort and return from orbit. The first two RTG Impact Tests were designed to provide information on the response of a fully loaded RTG to end-on impact against a concrete target. The results of these tests indicated that at impact velocities up to 57 m/s the converter shell and internal components protect the GPHS capsules from excessive deformation. At higher velocities, some of the internal components of the RTG interact with the GPHS capsules to cause excessive localized deformation and failure

Conventional fuel tank blunt impact tests : test and analysis results

Science.gov (United States)

2014-04-02

The Federal Railroad Administrations Office of Research : and Development is conducting research into fuel tank : crashworthiness. A series of impact tests are planned to : measure fuel tank deformation under two types of dynamic : loading conditi...

Kilometer-Scale Transient Atmospheres for Kinetic Payload Deposition on Icy Bodies

Science.gov (United States)

Koch, James

Entry, descent, and landing technologies for space exploration missions to atmospheric bodies traditionally exploit the body's ambient atmosphere as a medium through which a spacecraft or probe can interact to transfer momentum and energy for a soft landing. For bodies with no appreciable atmosphere, a significant engineering challenge exists to overcome the lack of passive methods to decelerate a spacecraft or probe. Proposed is a novel means for the creation of a transient atmosphere for airless icy bodies through the use of a two stage payload-penetrator probe. The first stage is a hyper-velocity penetrator that impacts the icy body. The second stage is an aero-braking-capable probe directed to pass through the ejecta plume from the hyper-velocity impact. Both experimental and computational studies show that a controlled high-energy impact can direct and transfer energy and momentum to a probe via a collimated ejecta plume. In an effort to provide clarity to this unexplored class of missions, a modeling-based engineering approach is taken to provide a first-order estimation of some of the involved physical phenomena. Three sub-studies are presented: an examination and characterization of ice plumes, modeling plume-probe interaction, and the extension of plume modeling as the basis for conceptual mission design. The modeling efforts are centered about two modeling formulations: smoothed particle hydrodynamics (SPH) and the arbitrary Largrangian-Eulerian (ALE) set of techniques. A database of fully-developed hypervelocity impacts and their associated plumes is created and used as inputs to a 1-D mathematical model for the interaction of a continuum-based plume and probe. A parametric study based on the hyper-velocity impact and staging of the probe-penetrator system is presented and discussed. Shown is that a tuned penetrator-probe mission has the potential to increase spacecraft payload mass fraction over conventional soft landing schemes.

GA-4/GA-9 honeycomb impact limiter tests and analytical model

International Nuclear Information System (INIS)

Koploy, M.A.; Taylor, C.S.

1991-01-01

General Atomics (GA) has a test program underway to obtain data on the behavior of a honeycomb impact limiter. The program includes testing of small samples to obtain basic information, as well as testing of complete 1/4-scale impact limiters to obtain load-versus-deflection curves for different crush orientations. GA has used the test results to aid in the development of an analytical model to predict the impact limiter loads. The results also helped optimize the design of the impact limiters for the GA-4 and GA-9 Casks

Statistical analysis and planning of multihundred-watt impact tests

International Nuclear Information System (INIS)

Martz, H.F. Jr.; Waterman, M.S.

1977-10-01

Modular multihundred-watt (MHW) radioisotope thermoelectric generators (RTG's) are used as a power source for spacecraft. Due to possible environmental contamination by radioactive materials, numerous tests are required to determine and verify the safety of the RTG. There are results available from 27 fueled MHW impact tests regarding hoop failure, fingerprint failure, and fuel failure. Data from the 27 tests are statistically analyzed for relationships that exist between the test design variables and the failure types. Next, these relationships are used to develop a statistical procedure for planning and conducting either future MHW impact tests or similar tests on other RTG fuel sources. Finally, some conclusions are given

Tests of spinning turbine fragment impact on casing models

International Nuclear Information System (INIS)

Wilbeck, J.S.

1984-01-01

Ten 1/11-scale model turbine missile impact tests were conducted at a Naval spin chamber test facility to assess turbine missile effects in nuclear plant design. The objective of the tests was to determine the effects of missile spin, blade crush, and target edge conditions on the impact of turbine disk fragments on the steel casing. The results were intended for use in making realistic estimates for the initial conditions of fragments that might escape the casing in the event of a disk burst in a nuclear plant. The burst of a modified gas turbine rotor in a high-speed spin chamber provided three missiles with the proper rotational and translational velocities of actual steam turbine fragments. Tests of bladed, spinning missiles were compared with previous tests of unbladed, nonspinning missiles. The total residual energy of the spinning missiles, as observed from high-speed photographs of disk burst, was the same as that of the nonspinning missiles launched in a piercing orientation. Tests with bladed missiles showed that for equal burst speeds, the residual energy of bladed missiles is less than that of unbladed missiles. Impacts of missiles near the edge of targets resulted in residual missile velocities greater than for central impact. (orig.)

Carbonaceous Survivability on Impact

Science.gov (United States)

Bunch, T. E.; Becker, Luann; Morrison, David (Technical Monitor)

1994-01-01

In order to gain knowledge about the potential contributions of comets and cosmic dust to the origin of life on Earth, we need to explore the survivability of their potential organic compounds on impact and the formation of secondary products that may have arisen from the chaotic events sustained by the carriers as they fell to Earth. We have performed a series of hypervelocity impact experiments using carbon-bearing impactors (diamond, graphite, kerogens, PAH crystals, and Murchison and Nogoya meteorites) into Al plate targets at velocities - 6 km/s. Estimated peak shock pressures probably did not exceed 120 GPa and peak shock temperatures were probably less than 4000 K for times of nano- to microsecs. Nominal crater dia. are less than one mm. The most significant results of these experiments are the preservation of the higher mass PAHs (e. g., pyrene relative to napthalene) and the formation of additional alkylated PAHs. We have also examined the residues of polystyrene projectiles impacted by a microparticle accelerator into targets at velocities up to 15 km/s. This talk will discuss the results of these experiments and their implications with respect to the survival of carbonaceous deliverables to early Earth. The prospects of survivability of organic molecules on "intact" capture of cosmic dust in space via soft: and hard cosmic dust collectors will also be discussed.

Relaxation near Supermassive Black Holes Driven by Nuclear Spiral Arms: Anisotropic Hypervelocity Stars, S-stars, and Tidal Disruption Events

Energy Technology Data Exchange (ETDEWEB)

Hamers, Adrian S. [Institute for Advanced Study, School of Natural Sciences, Einstein Drive, Princeton, NJ 08540 (United States); Perets, Hagai B., E-mail: hamers@ias.edu [Technion—Israel Institute of Technology, Haifa 32000 (Israel)

2017-09-10

Nuclear spiral arms are small-scale transient spiral structures found in the centers of galaxies. Similarly to their galactic-scale counterparts, nuclear spiral arms can perturb the orbits of stars. In the case of the Galactic center (GC), these perturbations can affect the orbits of stars and binaries in a region extending to several hundred parsecs around the supermassive black hole (SMBH), causing diffusion in orbital energy and angular momentum. This diffusion process can drive stars and binaries to close approaches with the SMBH, disrupting single stars in tidal disruption events (TDEs), or disrupting binaries, leaving a star tightly bound to the SMBH and an unbound star escaping the galaxy, i.e., a hypervelocity star (HVS). Here, we consider diffusion by nuclear spiral arms in galactic nuclei, specifically the Milky Way GC. We determine nuclear-spiral-arm-driven diffusion rates using test-particle integrations and compute disruption rates. Our TDE rates are up to 20% higher compared to relaxation by single stars. For binaries, the enhancement is up to a factor of ∼100, and our rates are comparable to the observed numbers of HVSs and S-stars. Our scenario is complementary to relaxation driven by massive perturbers. In addition, our rates depend on the inclination of the binary with respect to the Galactic plane. Therefore, our scenario provides a novel potential source for the observed anisotropic distribution of HVSs. Nuclear spiral arms may also be important for accelerating the coalescence of binary SMBHs and for supplying nuclear star clusters with stars and gas.

THE NATURE OF HYPERVELOCITY STARS AND THE TIME BETWEEN THEIR FORMATION AND EJECTION

Energy Technology Data Exchange (ETDEWEB)

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Cohen, Judith G., E-mail: wbrown@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: jlc@astro.caltech.edu [Palomar Observatory, Mail Stop 249-17, California Institute of Technology, Pasadena, CA 91125 (United States)

2012-07-20

We obtain Keck HIRES spectroscopy of HVS5, one of the fastest unbound stars in the Milky Way halo. We show that HVS5 is a 3.62 {+-} 0.11 M{sub Sun} main-sequence B star at a distance of 50 {+-} 5 kpc. The difference between its age and its flight time from the Galactic center is 105 {+-} 18 (stat) {+-}30 (sys) Myr; flight times from locations elsewhere in the Galactic disk are similar. This 10{sup 8} yr 'arrival time' between formation and ejection is difficult to reconcile with any ejection scenario involving massive stars that live for only 10{sup 7} yr. For comparison, we derive arrival times of 10{sup 7} yr for two unbound runaway B stars, consistent with their disk origin where ejection results from a supernova in a binary system or dynamical interactions between massive stars in a dense star cluster. For HVS5, ejection during the first 10{sup 7} yr of its lifetime is ruled out at the 3{sigma} level. Together with the 10{sup 8} yr arrival times inferred for three other well-studied hypervelocity stars (HVSs), these results are consistent with a Galactic center origin for the HVSs. If the HVSs were indeed ejected by the central black hole, then the Galactic center was forming stars {approx_equal}200 Myr ago, and the progenitors of the HVSs took {approx_equal}100 Myr to enter the black hole's loss cone.

THE NATURE OF HYPERVELOCITY STARS AND THE TIME BETWEEN THEIR FORMATION AND EJECTION

International Nuclear Information System (INIS)

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.; Cohen, Judith G.

2012-01-01

We obtain Keck HIRES spectroscopy of HVS5, one of the fastest unbound stars in the Milky Way halo. We show that HVS5 is a 3.62 ± 0.11 M ☉ main-sequence B star at a distance of 50 ± 5 kpc. The difference between its age and its flight time from the Galactic center is 105 ± 18 (stat) ±30 (sys) Myr; flight times from locations elsewhere in the Galactic disk are similar. This 10 8 yr 'arrival time' between formation and ejection is difficult to reconcile with any ejection scenario involving massive stars that live for only 10 7 yr. For comparison, we derive arrival times of 10 7 yr for two unbound runaway B stars, consistent with their disk origin where ejection results from a supernova in a binary system or dynamical interactions between massive stars in a dense star cluster. For HVS5, ejection during the first 10 7 yr of its lifetime is ruled out at the 3σ level. Together with the 10 8 yr arrival times inferred for three other well-studied hypervelocity stars (HVSs), these results are consistent with a Galactic center origin for the HVSs. If the HVSs were indeed ejected by the central black hole, then the Galactic center was forming stars ≅200 Myr ago, and the progenitors of the HVSs took ≅100 Myr to enter the black hole's loss cone.

Impact Testing of Orbiter Thermal Protection System Materials

Science.gov (United States)

Kerr, Justin

2006-01-01

This viewgraph presentation reviews the impact testing of the materials used in designing the shuttle orbiter thermal protection system (TPS). Pursuant to the Columbia Accident Investigation Board recommendations a testing program of the TPS system was instituted. This involved using various types of impactors in different sizes shot from various sizes and strengths guns to impact the TPS tiles and the Leading Edge Structural Subsystem (LESS). The observed damage is shown, and the resultant lessons learned are reviewed.

The Impact Imperative: A Space Infrastructure Enabling a Multi-Tiered Earth Defense

Science.gov (United States)

Campbell, Jonathan W.; Phipps, Claude; Smalley, Larry; Reilly, James; Boccio, Dona

2003-01-01

Impacting at hypervelocity, an asteroid struck the Earth approximately 65 million years ago in the Yucatan Peninsula a m . This triggered the extinction of almost 70% of the species of life on Earth including the dinosaurs. Other impacts prior to this one have caused even greater extinctions. Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most important immediate space challenge facing human civilization. This is the Impact Imperative. We now believe that while there are about 2000 earth orbit crossing rocks greater than 1 kilometer in diameter, there may be as many as 200,000 or more objects in the 100 m size range. Can anything be done about this fundamental existence question facing our civilization? The answer is a resounding yes! By using an intelligent combination of Earth and space based sensors coupled with an infrastructure of high-energy laser stations and other secondary mitigation options, we can deflect inbound asteroids, meteoroids, and comets and prevent them &om striking the Earth. This can be accomplished by irradiating the surface of an inbound rock with sufficiently intense pulses so that ablation occurs. This ablation acts as a small rocket incrementally changing the shape of the rock's orbit around the Sun. One-kilometer size rocks can be moved sufficiently in about a month while smaller rocks may be moved in a shorter time span. We recommend that space objectives be immediately reprioritized to start us moving quickly towards an infrastructure that will support a multiple option defense capability. Planning and development for a lunar laser facility should be initiated immediately in parallel with other options. All mitigation options are greatly enhanced by robust early warning, detection, and tracking resources to find objects sufficiently prior to Earth orbit passage in time to allow significant intervention. Infrastructure options should include ground, LEO, GEO, Lunar, and libration point

Impact test of components

International Nuclear Information System (INIS)

Borsoi, L.; Buland, P.; Labbe, P.

1987-01-01

Stops with gaps are currently used to support components and piping: it is simple, low cost, efficient and permits free thermal expansion. In order to keep the nonlinear nature of stops, such design is often modeled by beam elements (for the component) and nonlinear springs (for the stops). This paper deals with the validity and the limits of these models through the comparison of computational and experimental results. The experimental results come from impact laboratory tests on a simplified mockup. (orig.)

Full scale aircraft impact test for evaluation of impact forces-Part 1

International Nuclear Information System (INIS)

Von Riesemann, W.A.; Parrish, R.L.; Bickel, D.C.; Heffelfinger, S.R.; Muto, K.; Sugano, T.; Tsubota, H.; Koshika, N.; Suzuki, M.; Ohrui, S.

1989-01-01

This paper describes a test conducted at an existing rocket sled facility in which an actual F-4 Phantom aircraft was impacted at a nominal velocity of 215 m/s into an essentially rigid block of concrete. This was accomplished by supporting the F-4 on four struts that were attached to the sled track by carriage shoes to direct the path of the aircraft. Propulsion was accomplished by two stages of rockets. The concrete target was floated on a set of air bearings. Data acquisition consisted of measurements of the acceleration of the fuselage and engines of the F-4, and measurements of the displacement, velocity and acceleration of the concrete target. High-speed photograph recorded the impact process and also permitted the determination of the impact velocity. This paper describes the test plan, method and results

Survival of organic materials in hypervelocity impacts of ice on sand, ice, and water in the laboratory.

Science.gov (United States)

Burchell, Mark J; Bowden, Stephen A; Cole, Michael; Price, Mark C; Parnell, John

2014-06-01

The survival of organic molecules in shock impact events has been investigated in the laboratory. A frozen mixture of anthracene and stearic acid, solvated in dimethylsulfoxide (DMSO), was fired in a two-stage light gas gun at speeds of ~2 and ~4 km s(-1) at targets that included water ice, water, and sand. This involved shock pressures in the range of 2-12 GPa. It was found that the projectile materials were present in elevated quantities in the targets after impact and in some cases in the crater ejecta as well. For DMSO impacting water at 1.9 km s(-1) and 45° incidence, we quantify the surviving fraction after impact as 0.44±0.05. This demonstrates successful transfer of organic compounds from projectile to target in high-speed impacts. The range of impact speeds used covers that involved in impacts of terrestrial meteorites on the Moon, as well as impacts in the outer Solar System on icy bodies such as Pluto. The results provide laboratory evidence that suggests that exogenous delivery of complex organic molecules from icy impactors is a viable source of such material on target bodies.

Testing of materials and scale models for impact limiters

International Nuclear Information System (INIS)

Maji, A.K.; Satpathi, D.; Schryer, H.L.

1991-01-01

Aluminum Honeycomb and Polyurethane foam specimens were tested to obtain experimental data on the material's behavior under different loading conditions. This paper reports the dynamic tests conducted on the materials and on the design and testing of scale models made out of these open-quotes Impact Limiters,close quotes as they are used in the design of transportation casks. Dynamic tests were conducted on a modified Charpy Impact machine with associated instrumentation, and compared with static test results. A scale model testing setup was designed and used for preliminary tests on models being used by current designers of transportation casks. The paper presents preliminary results of the program. Additional information will be available and reported at the time of presentation of the paper

The Impact of an Electronic Expensive Test Notification.

Science.gov (United States)

Riley, Jacquelyn D; Stanley, Glenn; Wyllie, Robert; Kottke-Marchant, Kandice; Procop, Gary W

2018-04-25

The impact of clinical decision support tools (CDSTs) that display test cost information has been variable. We retrospectively analyzed the 3-year impact of a passive CDST that notified providers when the test order cost was $1,000 or more. We determined the most common expensive tests ordered, the frequency with which providers abandoned the order after notification, and the costs saved through this intervention. The average monthly abandonment rate was 12.5% (2014), 12.9% (2015), and 14.3% (2016). The cost savings from tests not performed for this 3-year period was $696,007. Molecular hematopathology assays were the most frequently ordered tests, with variable abandonment rates. Although this CDST was passive (ie, could be overridden at the point of order entry) and was associated with a relatively low abandonment rate, it achieved a considerable cost savings each year since each abandoned test saved the institution $1,000 or more.

Impact test on natural fiber reinforced polymer composite materials

Directory of Open Access Journals (Sweden)

D. Chandramohan

2013-06-01

Full Text Available In this research, natural fibers like Sisal (Agave sisalana, Banana (Musa sepientum & Roselle (Hibiscus sabdariffa , Sisal and banana (hybrid , Roselle and banana (hybrid and Roselle and sisal (hybrid are fabricated with bio epoxy resin using molding method. In this work, impact strength of Sisal and banana (hybrid, Roselle and banana (hybridand Roselle and sisal (hybrid composite at dry and wet conditions were studied. Impact test were conducted izod impact testing machine. In this work micro structure of the specimens are scanned by the Scanning Electron Microscope.

SRL canister impact tests

International Nuclear Information System (INIS)

Kelker, J.W. Jr.

1986-05-01

The Defense Waste Processing Facility (DWPF) is being constructed at the SRP for the containerization of high-level nuclear waste as a waste form for eventual permanent disposal. The waste will be incorporated in molten glass and solidified in Type 304L stainless steel canisters 2 feet in diameter x 9 feet 10 inches long. The canisters have a minimum wall thickness of 3/8 inch. Over a three-year period, nineteen drop-tests of nine canisters, filled with simulated waste glass, were made in support of the DWPF containerization program. Eight of the canister evaluation tests were of Type 304L stainless steel material and one was of commercially pure titanium. Three different length (9.44, 5.06, and 7.88 inch) nozzle configurations containing final closure upset welds were evaluated for the stainless steel canisters. All impact tests of the stainless steel canisters, which included bottom-, side-, and top-drops, were acceptable. The bottom-drop test of the titanium canister, which contained a final closure upset weld, was acceptable; however, the top-drop resulted in a breaching of the top head where it joins the nozzle. The final closure titanium upset weld was acceptable. The titanium canister wall thickness was 1/4 inch

Impact Strength of Natural Fibre Composites Measured by Different Test Methods: A Review

Directory of Open Access Journals (Sweden)

Navaranjan Namasivayam

2017-01-01

Full Text Available Different types of impact test methods have been used in recent years to measure the impact resistance of natural fibre composites (NFCs. After reviewing the literature, the impact resistance of flax, hemp, sisal, wood and jute fibre composites that were measured using different test methods have been compared and discussed. It has been learned that the test methods were selected for research interest, industry requirement or availability of test equipment. Each method had its own advantages and limitations. The result from a particular test could be compared but not with the result from other test methods. Most impact test methods were developed for testing ductile-brittle transition of metals. However, each NFC has a different morphology and cannot be comparable to metals in failure mode and energy absorption characteristic during an impact test. A post evaluation of morphology of an NFC sample after an impact test is important to characterise the material.

Impact effects in thin-walled structures

International Nuclear Information System (INIS)

Zukas, J.A.; Gaskill, B.

1996-01-01

A key parameter in the design of protective structures is the critical impact velocity, also known as the ballistic limit. This is the velocity below which a striker will fail to penetrate a barrier or some protective device. For strikers with regular shapes, such as cylinders (long and short), spheres and cones, analytical and empirical formulations for the determination of a ballistic limit exist at impact velocities ranging from 250 m/s to 6 km/s or higher. For non-standard shapes, two- and three-dimensional wave propagation codes (hydrocodes) can be valuable adjuncts to experiments in ballistic limit determinations. This is illustrated with the help of the ZeuS code in determining the ballistic limit of a short, tubular projectile striking a thin aluminum barrier and contrasting it to the value of the ballistic limit of a spherical projectile of equal mass against the same target. Several interesting features of the debris cloud generated by a tubular projectile striking a Whipple shield at hypervelocity are also pointed out. The paper concludes with a consideration of hydrodynamic ram effects in fluid-filled thin-walled structures. Where possible, comparisons are made of computed results with experimental data

Hybrid III anthropomorphic test device (ATD) response to head impacts and potential implications for athletic headgear testing.

Science.gov (United States)

Bartsch, Adam; Benzel, Edward; Miele, Vincent; Morr, Douglas; Prakash, Vikas

2012-09-01

The Hybrid III 50th percentile male anthropomorphic test device (ATD) is the most widely used human impact testing surrogate and has historically been used in automotive or military testing. More recently, this ATD is finding use in applications evaluating athletic helmet protectivity, quantifying head impact dosage and estimating injury risk. But ATD head-neck response has not been quantified in omnidirectional athletic-type head impacts absent axial preload. It is probable that headgear injury reduction that can be quantified in a laboratory, including in American football, boxing, hockey, lacrosse and soccer, is related to a number of interrelated kinetic and kinematic factors, such as head center of gravity linear acceleration, head angular acceleration, head angular velocity, occipito-cervical mechanics and neck stiffness. Therefore, we characterized ATD head-neck dynamic response to direct head impacts in a series of front, oblique front and lateral head impacts. Key findings were: (1) impacts producing highest ATD resultant center of gravity linear acceleration resulted in the lowest resultant occipito-cervical spine bending moment/force. (2) Resultant ATD head angular velocity and angular acceleration did not appear coupled to impact direction at lower impact energy levels; these parameters were coupled at higher energy levels. (3) The ATD had progressively increasing occipito-cervical stiffness in extension, torsion and lateral bending, respectively. Because the ATD neck influenced head and neck impact dosage parameters, testing agencies, manufacturers and researchers should consider using the Hybrid III head form attached to a neck as a means to quantify head and neck injury risks as opposed to systems that do not utilize a neck. This heightened understanding of Hybrid III ATD head-neck response, and consideration of order of stiffest axes in the lateral, oblique and extension directions, respectively, should aid in the development of head and neck injury

The use of scale models in impact testing

International Nuclear Information System (INIS)

Donelan, P.J.; Dowling, A.R.

1985-01-01

Theoretical analysis, component testing and model flask testing are employed to investigate the validity of scale models for demonstrating the behaviour of Magnox flasks under impact conditions. Model testing is shown to be a powerful and convenient tool provided adequate care is taken with detail design and manufacture of models and with experimental control. (author)

Scaling of heat transfer augmentation due to mechanical distortions in hypervelocity boundary layers

Science.gov (United States)

Flaherty, W.; Austin, J. M.

2013-10-01

We examine the response of hypervelocity boundary layers to global mechanical distortions due to concave surface curvature. Surface heat transfer and visual boundary layer thickness data are obtained for a suite of models with different concave surface geometries. Results are compared to predictions using existing approximate methods. Near the leading edge, good agreement is observed, but at larger pressure gradients, predictions diverge significantly from the experimental data. Up to a factor of five underprediction is reported in regions with greatest distortion. Curve fits to the experimental data are compared with surface equations. We demonstrate that reasonable estimates of the laminar heat flux augmentation may be obtained as a function of the local turning angle for all model geometries, even at the conditions of greatest distortion. This scaling may be explained by the application of Lees similarity. As a means of introducing additional local distortions, vortex generators are used to impose streamwise structures into the boundary layer. The response of the large scale vortices to an adverse pressure gradient is investigated. Surface streak evolution is visualized over the different surface geometries using fast response pressure sensitive paint. For a flat plate baseline case, heat transfer augmentation at similar levels to turbulent flow is measured. For the concave geometries, increases in heat transfer by factors up to 2.6 are measured over the laminar values. The scaling of heat transfer with turning angle that is identified for the laminar boundary layer response is found to be robust even in the presence of the imposed vortex structures.

Geological remote sensing signatures of terrestrial impact craters

International Nuclear Information System (INIS)

Garvin, J.B.; Schnetzler, C.; Grieve, R.A.F.

1988-01-01

Geological remote sensing techniques can be used to investigate structural, depositional, and shock metamorphic effects associated with hypervelocity impact structures, some of which may be linked to global Earth system catastrophies. Although detailed laboratory and field investigations are necessary to establish conclusive evidence of an impact origin for suspected crater landforms, the synoptic perspective provided by various remote sensing systems can often serve as a pathfinder to key deposits which can then be targetted for intensive field study. In addition, remote sensing imagery can be used as a tool in the search for impact and other catastrophic explosion landforms on the basis of localized disruption and anomaly patterns. In order to reconstruct original dimensions of large, complex impact features in isolated, inaccessible regions, remote sensing imagery can be used to make preliminary estimates in the absence of field geophysical surveys. The experienced gained from two decades of planetary remote sensing of impact craters on the terrestrial planets, as well as the techniques developed for recognizing stages of degradation and initial crater morphology, can now be applied to the problem of discovering and studying eroded impact landforms on Earth. Preliminary results of remote sensing analyses of a set of terrestrial impact features in various states of degradation, geologic settings, and for a broad range of diameters and hence energies of formation are summarized. The intention is to develop a database of remote sensing signatures for catastrophic impact landforms which can then be used in EOS-era global surveys as the basis for locating the possibly hundreds of missing impact structures

Developing the impact testing module with labVIEW

International Nuclear Information System (INIS)

Choi, Ki Soo; Jeon, Soo Hong; Jeong, Weui Bong

2007-01-01

Fast Fourier Transformation (FFT) is one of the most useful way to analyze response signal for the purpose of grasping the dynamic characteristics of system. Vibration test using impact hammer is typical and simple experimental method widely used for catching hold of dynamic peculiar characters and modal behaviors of system. In this thesis, impact testing module for NI-PXI equipment is developed. The analyzing and visualizing module are developed with labVIEW tool. A user can see quickly and easily modal shape of system after analyzing acquired data. This developed module will be expected to build up more convenient and serviceable measurement system

Impact of presymptomatic genetic testing for hereditary ataxia and neuromuscular disorders.

Science.gov (United States)

Smith, Corrine O; Lipe, Hillary P; Bird, Thomas D

2004-06-01

With the exception of Huntington disease, the psychological and psychosocial impact of DNA testing for neurogenetic disorders has not been well studied. To evaluate the psychosocial impact of genetic testing for autosomal dominant forms of hereditary ataxia and neuromuscular disorders. Patients Fifty subjects at risk for autosomal dominant forms of spinocerebellar ataxia (n = 11), muscular dystrophy (n = 28), and hereditary neuropathy (n = 12). A prospective, descriptive, observational study in a university setting of individuals who underwent genetic counseling and DNA testing. Participants completed 3 questionnaires before testing and at regular intervals after testing. The questionnaire set included the Revised Impact of Event Scale, the Hospital Anxiety and Depression Scale, demographic information, and an assessment of attitudes and feelings about genetic testing. Thirty-nine subjects (78%) completed 6 months to 5 years of posttest follow-up. Common reasons for pursuing genetic testing were to provide an explanation for symptoms, emotional relief, and information for future planning. Thirty-four (68%) had positive and 16 (32%) had negative genetic results. In those with a positive result, 26 (76%) had nonspecific signs or symptoms of the relevant disorder. Forty-two participants (84%) felt genetic testing was beneficial. Groups with positive and negative test results coped well with results. However, 13 subjects (10 with positive and 3 with negative results) reported elevated anxiety levels, and 3 (1 with positive and 2 with negative results) expressed feelings of depression during the follow-up period. The test result was not predictive of anxiety or depression. Most individuals find neurogenetic testing to be beneficial, regardless of the result. Anxiety or depression may persist in some persons with positive or negative test results. Testing can have a demonstrable impact on family planning and interpersonal relationships. Further studies are needed to

Microstructural characterization of Charpy-impact-tested nanostructured bainite

Energy Technology Data Exchange (ETDEWEB)

Tsai, Y.T.; Chang, H.T.; Huang, B.M. [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC (China); Huang, C.Y. [Iron and Steel R& D Department, China Steel Corporation, Kaohsiung, Taiwan, ROC (China); Yang, J.R., E-mail: jryang@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC (China)

2015-09-15

In this work, a possible cause of the extraordinary low impact toughness of nanostructured bainite has been investigated. The microstructure of nanostructured bainite consisted chiefly of carbide-free bainitic ferrite with retained austenite films. X-ray diffractometry (XRD) measurement indicated that no retained austenite existed in the fractured surface of the Charpy-impact-tested specimens. Fractographs showed that cracks propagated mainly along bainitic ferrite platelet boundaries. The change in microstructure after impact loading was verified by transmission electron microscopy (TEM) observations, confirming that retained austenite was completely transformed to strain-induced martensite during the Charpy impact test. However, the zone affected by strained-induced martensite was found to be extremely shallow, only to a depth of several micrometers from the fracture surface. It is appropriately concluded that upon impact, as the crack forms and propagates, strain-induced martensitic transformation immediately occurs ahead of the advancing crack tip. The successive martensitic transformation profoundly facilitates the crack propagation, resulting in the extremely low impact toughness of nanostructured bainite. Retained austenite, in contrast to its well-known beneficial role, has a deteriorating effect on toughness during the course of Charpy impact. - Highlights: • The microstructure of nanostructured bainite consisted of nano-sized bainitic ferrite subunits with retained austenite films. • Special sample preparations for SEM, XRD and TEM were made, and the strain-affected structures have been explored. • Retained austenite films were found to transform into martensite after impact loading, as evidenced by XRD and TEM results. • The zone of strain-induced martensite was found to extend to only several micrometers from the fracture surface. • The poor Charpy impact toughness is associated with the fracture of martensite at a high strain rate during

The Impact of IPv6 on Penetration Testing

NARCIS (Netherlands)

Ottow, Christiaan; van Vliet, Frank; de Boer, Pieter-Tjerk; Pras, Aiko

In this paper we discuss the impact the use of IPv6 has on remote penetration testing of servers and web applications. Several modifications to the penetration testing process are proposed to accommodate IPv6. Among these modifications are ways of performing fragmentation attacks, host discovery and

Finite element analysis of car hood for impact test by using ...

African Journals Online (AJOL)

Finite element analysis of car hood for impact test by using solidworks software ... high safety and at the same time can be built according to market demands. ... Keywords: finite element analysis; impact test; Solidworks; automation, car hood.

Is the psychological impact of genetic testing moderated by support and sharing of test results to family and friends?

Science.gov (United States)

Lapointe, Julie; Dorval, Michel; Noguès, Catherine; Fabre, Roxane; Julian-Reynier, Claire

2013-12-01

Receiving the results of genetic tests for a breast and ovarian cancer susceptibility can be a stressful experience. Here we studied the effects of social support (SS) and the sharing of test results on the psychological impact of BRCA1/2 test result disclosure. We also compared carriers and non-carriers on sharing, SS and psychological impact. Five-hundred and twenty-two unaffected women were followed prospectively for 2 years after receiving their test results. Psychological impact was measured on the impact of event scale. Multivariate multi-level models were used, and all the analyses were stratified depending on mutation status (carriers vs non-carriers). Two weeks after receiving their BRCA1/2 results, carriers had shared their test results less frequently than non-carriers (p test results was not significantly associated with psychological impact. Availability of SS was significantly associated with better psychological adjustment across time among carriers (p importance of SS should be stressed, and possible ways of enlisting people in their entourage for this purpose should be discussed in the context of clinical encounters.

Risk Assessment of Cassini Sun Sensor Integrity Due to Hypervelocity Impact of Saturn Dust Particles

Science.gov (United States)

Lee, Allan Y.

2016-01-01

A sophisticated interplanetary spacecraft, Cassini is one of the heaviest and most sophisticated interplanetary spacecraft humans have ever built and launched. Since achieving orbit at Saturn in 2004, Cassini has collected science data throughout its four-year prime mission (2004-08), and has since been approved for first and second extended missions through September 2017. In late 2016, the Cassini spacecraft will begin a daring set of ballistic orbits that will hop the rings and dive between the upper atmosphere of Saturn and its innermost D-ring twenty-two times. The "dusty" environment of the inner D-ring region the spacecraft must fly through is hazardous because of the possible damage that dust particles, travelling at speeds as high as 31.4 km/s, can do to spacecraft hardware. During hazardous proximal ring-plane crossings, the Cassini mission operation team plans to point the high-gain antenna to the RAM vector in order to protect most of spacecraft instruments from the incoming energetic ring dust particles. However, this particular spacecraft attitude will expose two Sun sensors (that are mounted on the antenna dish) to the incoming dust particles. High-velocity impacts on the Sun sensor cover glass might penetrate the 2.54-mm glass cover of the Sun sensor. Even without penetration damage, craters created by these impacts on the surface of the cover glass will degrade the transmissibility of light through it. Apart from being directly impacted by the dust particles, the Sun sensors are also threatened by some fraction of ricochet ejecta that are produced by dust particle impacts on the large antenna dish (made of graphite fiber epoxy composite material). Finally, the spacecraft attitude control system must cope with disturbances due to both the translational and angular impulses imparted on the large antenna dish and the long magnetometer boom by the incoming high-velocity projectiles. Analyses performed to quantify the risks the Sun sensors must contend

Materials Characterization Center meeting on impact testing of waste forms. Summary report

International Nuclear Information System (INIS)

Merz, M.D.; Atteridge, D.; Dudder, G.

1981-10-01

A meeting was held on March 25-26, 1981 to discuss impact test methods for waste form materials to be used in nuclear waste repositories. The purpose of the meeting was to obtain guidance for the Materials Characterization Center (MCC) in preparing the MCC-10 Impact Test Method to be approved by the Materials Review Board. The meeting focused on two essential aspects of the test method, namely the mechanical process, or impact, used to effect rapid fracture of a waste form and the analysis technique(s) used to characterize particulates generated by the impact

A new tensile impact test for the toughness characterization of sheet material

Science.gov (United States)

Könemann, Markus; Lenz, David; Brinnel, Victoria; Münstermann, Sebastian

2018-05-01

In the past, the selection of suitable steels has been carried out primarily based on the mechanical properties of different steels. One of these properties is the resistance against crack propagation. For many constructions, this value plays an important role, because it can compare the impact toughness of different steel grades easily and gives information about the loading capacity of the specific materials. For thin sheets, impact toughness properties were usually not considered. One of the reasons for this is that the Charpy-impact test is not applicable for sheets with thicknesses below 2 mm. For a long time, this was not relevant because conventional steels had a sufficient impact toughness in a wide temperature range. However, since new multiphase steel grades with improved mechanical property exploitations are available, it turned out that impact toughness properties need to be considered during the component design phase, as the activation of the cleavage fracture mechanism is observed under challenging loading conditions. Therefore, this work aims to provide a new and practical testing procedure for sheet material or thin walled structures. The new testing procedure is based on tensile tests conducted in an impact pendulum similar to the Charpy impact hammer. A new standard geometry is provided, which enables a comparison between different steels or steel grades. A connection to the conventional Charpy test is presented using a damage mechanics model, which predicts material failure with consideration of to the stress state at various temperatures. Different specimen geometries are analysed to cover manifold stress states. A special advantage of the damage mechanics model is also the possibility to predict the materials behaviour in the transition area. To verify the method a conventional steel was tested in Charpy tests as well as in the new tensile impact test.

Radioisotope thermoelectric generator/thin fragment impact test

International Nuclear Information System (INIS)

Reimus, M.A.H.; Hinckley, J.E.

1998-01-01

The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of 238 Pu decay to an array of thermoelectric elements in a radioisotope thermoelectric generator (RTG). Because the potential for a launch abort or return from orbit exists for any space mission, the heat source response to credible accident scenarios is being evaluated. This test was designed to provide information on the response of a loaded RTG to impact by a fragment similar to the type of fragment produced by breakup of the spacecraft propulsion module system (PMS). The results of this test indicated that impact of the RTG by a thin aluminum fragment traveling at 306 m/s may result in significant damage to the convertor housing, failure of one fueled clad, and release of a small quantity of fuel

Impact Tensile Testing of Stainless Steels at Various Temperatures

Energy Technology Data Exchange (ETDEWEB)

D. K. Morton

2008-03-01

Stainless steels are used for the construction of numerous spent nuclear fuel or radioactive material containers that may be subjected to high strains and moderate strain rates during accidental drop events. Mechanical characteristics of these base materials and their welds under dynamic loads in the strain rate range of concern (1 to 300 per second) are not well documented. However, research is being performed at the Idaho National Laboratory to quantify these characteristics. The work presented herein discusses tensile impact testing of dual-marked 304/304L and 316/316L stainless steel material specimens. Both base material and welded material specimens were tested at -20 oF, room temperature, 300 oF, and 600 oF conditions. Utilizing a drop weight impact test machine and 1/4-inch and 1/2-inch thick dog bone-shaped test specimens, a strain rate range of approximately 4 to 40 per second (depending on initial temperature conditions) was achieved. Factors were determined that reflect the amount of increased strain energy the material can absorb due to strain rate effects. Using the factors, elevated true stress-strain curves for these materials at various strain rates and temperatures were generated. By incorporating the strain rate elevated true stress-strain material curves into an inelastic finite element computer program as the defined material input, significant improvement in the accuracy of the computer analyses was attained. However, additional impact testing is necessary to achieve higher strain rates (up to 300 per second) before complete definition of strain rate effects can be made for accidental drop events and other similar energy-limited impulsive loads. This research approach, using impact testing and a total energy analysis methodology to quantify strain rate effects, can be applied to many other materials used in government and industry.

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

Impacts on the Hubble Space Telescope Wide Field and Planetary Camera 2: Microanalysis and Recognition of Micrometeoroid Compositions

Science.gov (United States)

Kearsley, A. T.; Ross, D. K.; Anz-Meador, P.; Liou, J. C.; Opiela, J.; Grime, G. W.; Webb, R. P.; Jeynes, C.; Palitsin, V. V.; Colaux, J. L.;

Large Field Photogrammetry Techniques in Aircraft and Spacecraft Impact Testing

Science.gov (United States)

Littell, Justin D.

2010-01-01

The Landing and Impact Research Facility (LandIR) at NASA Langley Research Center is a 240 ft. high A-frame structure which is used for full-scale crash testing of aircraft and rotorcraft vehicles. Because the LandIR provides a unique capability to introduce impact velocities in the forward and vertical directions, it is also serving as the facility for landing tests on full-scale and sub-scale Orion spacecraft mass simulators. Recently, a three-dimensional photogrammetry system was acquired to assist with the gathering of vehicle flight data before, throughout and after the impact. This data provides the basis for the post-test analysis and data reduction. Experimental setups for pendulum swing tests on vehicles having both forward and vertical velocities can extend to 50 x 50 x 50 foot cubes, while weather, vehicle geometry, and other constraints make each experimental setup unique to each test. This paper will discuss the specific calibration techniques for large fields of views, camera and lens selection, data processing, as well as best practice techniques learned from using the large field of view photogrammetry on a multitude of crash and landing test scenarios unique to the LandIR.

Simulated hail impact testing of photovoltaic solar panels

Science.gov (United States)

Moore, D.; Wilson, A.; Ross, R.

1978-01-01

Techniques used to simulate and study the effect of hail on photovoltaic solar panels are described. Simulated hail stones (frozen ice spheres projected at terminal velocity) or steel balls were applied by air guns, gravity drop, or static loading. Tests with simulated hail and steel balls yielded different results. The impact strength of 10 commercially available flat-plate photovoltaic modules was tested. It was found that none of the six panel designs incorporating clear potting silicone material as the outermost layer remained undamaged by 1-in. simulated hailstones, while a photovoltaic module equipped with a 0.188-in.-thick acrylic cover sheet would be able to withstand the impact of a 2-in.-diameter hailstone.

Elemental Water Impact Test: Phase 2 36-Inch Aluminum Tank Head

Science.gov (United States)

Vassilakos, Gregory J.

2014-01-01

Spacecraft are being designed based on LS-DYNA simulations of water landing impacts. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. EWIT Phase 2 featured a 36-inch aluminum tank head. The tank head was outfitted with one accelerometer, twelve pressure transducers, three string potentiometers, and four strain gages. The tank head was dropped from heights of 1 foot and 2 feet. The focus of this report is the correlation of analytical models against test data. As a measure of prediction accuracy, peak responses from the baseline LS-DYNA model were compared to peak responses from the tests.

Optimal design and dynamic impact tests of removable bollards

Science.gov (United States)

Chen, Suwen; Liu, Tianyi; Li, Guoqiang; Liu, Qing; Sun, Jianyun

2017-10-01

Anti-ram bollard systems, which are installed around buildings and infrastructure, can prevent unauthorized vehicles from entering, maintain distance from vehicle-borne improvised explosive devices (VBIED) and reduce the corresponding damage. Compared with a fixed bollard system, a removable bollard system provides more flexibility as it can be removed when needed. This paper first proposes a new type of K4-rated removable anti-ram bollard system. To simulate the collision of a vehicle hitting the bollard system, a finite element model was then built and verified through comparison of numerical simulation results and existing experimental results. Based on the orthogonal design method, the factors influencing the safety and economy of this proposed system were examined and sorted according to their importance. An optimal design scheme was then produced. Finally, to validate the effectiveness of the proposed design scheme, four dynamic impact tests, including two front impact tests and two side impact tests, have been conducted according to BSI Specifications. The residual rotation angles of the specimen are smaller than 30º and satisfy the requirements of the BSI Specification.

Development of estimation algorithm of loose parts and analysis of impact test data

International Nuclear Information System (INIS)

Kim, Jung Soo; Ham, Chang Sik; Jung, Chul Hwan; Hwang, In Koo; Kim, Tak Hwane; Kim, Tae Hwane; Park, Jin Ho

1999-11-01

Loose parts are produced by being parted from the structure of the reactor coolant system or by coming into RCS from the outside during test operation, refueling, and overhaul time. These loose parts are mixed with reactor coolant fluid and collide with RCS components. When loose parts are occurred within RCS, it is necessary to estimate the impact point and the mass of loose parts. In this report an analysis algorithm for the estimation of the impact point and mass of loose part is developed. The developed algorithm was tested with the impact test data of Yonggwang-3. The estimated impact point using the proposed algorithm in this report had 5 percent error to the real test data. The estimated mass was analyzed within 28 percent error bound using the same unit's data. We analyzed the characteristic frequency of each sensor because this frequency effected the estimation of impact point and mass. The characteristic frequency of the background noise during normal operation was compared with that of the impact test data. The result of the comparison illustrated that the characteristic frequency bandwidth of the impact test data was lower than that of the background noise during normal operation. by the comparison, the integrity of sensor and monitoring system could be checked, too. (author)

Human-Robot Collaboration Dynamic Impact Testing and Calibration Instrument for Disposable Robot Safety Artifacts.

Science.gov (United States)

Dagalakis, Nicholas G; Yoo, Jae Myung; Oeste, Thomas

2016-01-01

The Dynamic Impact Testing and Calibration Instrument (DITCI) is a simple instrument with a significant data collection and analysis capability that is used for the testing and calibration of biosimulant human tissue artifacts. These artifacts may be used to measure the severity of injuries caused in the case of a robot impact with a human. In this paper we describe the DITCI adjustable impact and flexible foundation mechanism, which allows the selection of a variety of impact force levels and foundation stiffness. The instrument can accommodate arrays of a variety of sensors and impact tools, simulating both real manufacturing tools and the testing requirements of standards setting organizations. A computer data acquisition system may collect a variety of impact motion, force, and torque data, which are used to develop a variety of mathematical model representations of the artifacts. Finally, we describe the fabrication and testing of human abdomen soft tissue artifacts, used to display the magnitude of impact tissue deformation. Impact tests were performed at various maximum impact force and average pressure levels.

Soft impact testing of a wall-floor-wall reinforced concrete structure

Energy Technology Data Exchange (ETDEWEB)

Vepsä, Ari, E-mail: ari.vepsa@vtt.fi; Calonius, Kim; Saarenheimo, Arja; Aatola, Seppo; Halonen, Matti

2017-01-15

Highlights: • A wall-floor-wall reinforced concrete structure was built. • The structure was subjected to three almost identical soft impact tests. • Response was measured with accelerometers, displacement sensors and strain gauges. • Modal tests was also carried out with the same structure in different conditions. • The results are meant to be used for validation of computational methods and models. - Abstract: Assessing the safety of the reactor building of a nuclear power plant against the crash of an airplane calls for valid computational tools such as finite element models and material constitutive models. Validation of such tools and models in turn calls for reliable and relevant experimental data. The problem is that such data is scarcely available. One of the aspects of such a crash is vibrations that are generated by the impact. These vibrations tend to propagate from the impact point to the internal parts of the building. If strong enough, these vibrations may cause malfunction of the safety-critical equipment inside the building. To enable validation of computational models for this type of behaviour, we have conducted a series of three tests with a wall-floor-wall reinforced concrete structure under soft impact loading. The response of the structure was measured with accelerometers, displacement sensors and strain gauges. In addition to impact tests, the structure was subjected to modal tests under different conditions. The tests yielded a wealth of useful data for validation of computational models and better understanding about shock induced vibration physics especially in reinforced concrete structures.

Full-scale impact test data for tornado-missile design of nuclear plants

International Nuclear Information System (INIS)

Stephenson, A.E.; Sliter, G.E.

1977-01-01

It is standard practice to consider the effects of low-probability impacts of tornado-borne debris (''tornado missiles'' such as utility poles and steel pipes) in the structural design of nuclear power plants in the United States. To provide data that can be used directly in the design procedure, a series of full-scale tornado-missile impact tests was performed. This paper is a brief summary of the results and conclusions from these tests. The tests consisted of reinforced concrete panels impacted by poles, pipes, and rods propelled by a rocket sled. The panels were constructed to current minimum standards and had thicknesses typical of auxiliary buildings of nuclear power plants. A specific objective was the determination of the impact velocities below which the panels do not experience backface scabbing. Another objective was to assess the adequacy of (1) conventional design formulae for penetration and scabbing and (2) conventional design methods for overall structural response. Test missiles and velocities represented those in current design standards. Missiles included utility poles, steel pipes, and steel bars. It is important to interpret the data in this paper in recognition that the test conditions represent conservative assumptions regarding maximum wind speeds, injection of the missile into the wind stream, aerodynamic trajectory, and orientation of missile at impact. Even with the severe assumptions made, the full-scale tests described demonstrate the ability of prototypical nuclear plant walls and roofs to provide adequate protection against postulated tornado-missile impact

Investigation on impact resistance of steel plate reinforced concrete barriers against aircraft impact. Pt.2: Simulation analysis of scale model impact tests

International Nuclear Information System (INIS)

Jun Mizuno; Norihide Koshika; Hiroshi Morikawa; Kentaro Wakimoto; Ryusuke Fukuda

2005-01-01

Steel plate reinforced concrete (SC) structure is one in which the rebars of conventional reinforced concrete (RC) structures are replaced with external steel plates attached to inner concrete with headed studs. SC structures are considered to be more effective than RC structures against aircraft impact, so their application to outer walls and roofs of risk-sensitive structures such as nuclear-related structures is expected to mitigate damage to critical components. The objective of this study was to investigate the fracture behavior and perforation thickness of SC panels against aircraft impact through impact tests and simulation analyses. Objectives of this paper are to analytically investigate the protection performance of SC panels against aircraft model impact through simulation analyses of 1/7.5 scale aircraft model impact tests presented in Part 1 of this study using a discrete element method (DEM), and to examine the applicability and validity of the DEM. Simulation analyses by a finite element method (FEM) were also performed to evaluate its applicability. The fracture process and damage to the SC test panels as well as the aircraft models are closely simulated by the discrete element analyses. The various impact responses and failure mechanisms, such as deceleration curves of projectile, velocity of debris from rear face and deformation mode of SC panels, are also simulated closely by the DEM analyses. The results of analyses confirm the shock-proof performance of SC panels against aircraft impact, and the applicability and validity of DEM for evaluating the complex phenomena of an aircraft impact against an SC panel. The finite element analysis closely simulates the deformation of the SC test panel and strains of rear steel plate where the global bending deformation mode is dominant. (authors)

Impact test characterization of carbon-carbon composites for the thermoelectric space power system

International Nuclear Information System (INIS)

Romanoski, G.R.; Pih, Hui.

1995-01-01

Thirty-eight unique carbon-carbon composite materials of cylindrical architecture were fabricated by commercial vendors for evaluation as alternative impact shell materials for the modular heat source of the thermoelectric space power system. Characterization of these materials included gas gun impact tests where cylindrical specimens containing a mass simulant were fired at 55 m/s to impact a target instrumented to measure force. The force versus time output was analyzed to determine: peak force, acceleration, velocity, and displacement. All impact tests exhibited an equivalence between preimpact momentum and measured impulse. In addition, energy was conserved based on a comparison of preimpact kinetic energy and measured work. Impact test results showed that the currently specified material provided impact energy absorption comparable to the best alternatives considered to date

Full-scale tornado-missile impact tests. Interim report

International Nuclear Information System (INIS)

Stephenson, A.E.

1976-04-01

Seven completed initial tests are described with 4 types of hypothetical tornado-borne missiles (impacting reinforced concrete panels that are typical of walls in nuclear power facilities). The missiles were rocket propelled to velocities currently postulated as being attainable by debris in tornadoes. (1500-pound 35-foot long utility pole; 8-pound 1-inch Grade 60 reinforcing bar; 78-pound 3-inch Schedule 40 pipe; and 743-pound 12-inch Schedule 40 pipe;) The results show that a minimum thickness of 24 inches is sufficient to prevent backface scabbing from normal impacts of currently postulated tornado missiles and that existing power plant walls are adequate for the most severe conditions currently postulated by regulatory agencies. This report gives selected detailed data on the tests completed thus far, including strain, panel velocity, and reaction histories

Procedure on the Impact Characteristic Test for the One-sided and Thru-grid Spacer Grid

International Nuclear Information System (INIS)

Yoon, Kyung Ho; Kim, Jae Yong; Lee, Kang Hee; Song, Kee Nam

2006-09-01

In order to perform the one-sided and the through-grid impact tests for a new developed spacer grid, the drop type impact test machines were established. The dynamic impact test is to get some basic data for accident analysis such as impact strength, stiffness, and coefficient of the restitution. Furthermore, these developed test methods and procedures will be qualified standard for increasing the reliability of the test results. Chapter 2 provides an introduction to the test facilities and instrumentations. Chapter 3 describes on how spacer grid and the single span fuel assembly specimen will be prepared. In addition to this, how to set up these testing machines. Chapter 4 illustrates detail test procedure on how to acquire impact signal of the two kinds of the specimen. Chapter 5 deals with signal processing and analysis for the test data. Finally, chapter 6 summarise the overall test procedure and the test method

Impact Foam Testing for Multi-Mission Earth Entry Vehicle Applications

Science.gov (United States)

Glaab, Louis J.; Agrawal, Paul; Hawbaker, James

2013-01-01

Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes and retro-rockets, instead using built-in impact attenuators to absorb energy remaining at impact to meet landing loads requirements. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs and develop the trade space. Testing was conducted to characterize the material properties of several candidate impact foam attenuators to enhance M-SAPE analysis. In the current effort, two different Rohacell foams were tested to determine their thermal conductivity in support of MMEEV design applications. These applications include thermal insulation during atmospheric entry, impact attenuation, and post-impact thermal insulation in support of thermal soak analysis. Results indicate that for these closed-cell foams, the effect of impact is limited on thermal conductivity due to the venting of the virgin material gas and subsequent ambient air replacement. Results also indicate that the effect of foam temperature is significant compared to data suggested by manufacturer's specifications.

Dynamic Open-Rotor Composite Shield Impact Test Report

Science.gov (United States)

Seng, Silvia; Frankenberger, Charles; Ruggeri, Charles R.; Revilock, Duane M.; Pereira, J. Michael; Carney, Kelly S.; Emmerling, William C.

2015-01-01

The Federal Aviation Administration (FAA) is working with the European Aviation Safety Agency to determine the certification base for proposed new engines that would not have a containment structure on large commercial aircraft. Equivalent safety to the current fleet is desired by the regulators, which means that loss of a single fan blade will not cause hazard to the aircraft. NASA Glenn and Naval Air Warfare Center (NAWC) China Lake collaborated with the FAA Aircraft Catastrophic Failure Prevention Program to design and test a shield that would protect the aircraft passengers and critical systems from a released blade that could impact the fuselage. This report documents the live-fire test from a full-scale rig at NAWC China Lake. NASA provided manpower and photogrammetry expertise to document the impact and damage to the shields. The test was successful: the blade was stopped from penetrating the shield, which validates the design analysis method and the parameters used in the analysis. Additional work is required to implement the shielding into the aircraft.

Structural identification of short/middle span bridges by rapid impact testing: theory and verification

Science.gov (United States)

Zhang, Jian; Zhang, Q. Q.; Guo, S. L.; Xu, D. W.; Wu, Z. S.

2015-06-01

A structural strain flexibility identification method by processing the multiple-reference impact testing data is proposed. First, a kind of novel long-gauge fiber optic sensor is developed for structural macro-strain monitoring. Second, the multiple-reference impact testing technology is employed, during which both the impacting force and structural strain responses are measured. The impact testing technology has unique merit because it is able to extract exact structural frequency response functions (FRFs), while other test methods, for instance ambient tests, can only output the FRFs with scaled magnitudes. Most importantly, the originality of the article is that a method of identifying the structural strain flexibility characteristic from the impact test data has been proposed, which is useful for structural static strain prediction and capacity evaluation. Examples of a six meter simple supported beam and a multiple-span continuous beam bridge have successfully verified the effectiveness of the proposed method.

Structural identification of short/middle span bridges by rapid impact testing: theory and verification

International Nuclear Information System (INIS)

Zhang, Jian; Wu, Z S; Zhang, Q Q; Guo, S L; Xu, D W

2015-01-01

A structural strain flexibility identification method by processing the multiple-reference impact testing data is proposed. First, a kind of novel long-gauge fiber optic sensor is developed for structural macro-strain monitoring. Second, the multiple-reference impact testing technology is employed, during which both the impacting force and structural strain responses are measured. The impact testing technology has unique merit because it is able to extract exact structural frequency response functions (FRFs), while other test methods, for instance ambient tests, can only output the FRFs with scaled magnitudes. Most importantly, the originality of the article is that a method of identifying the structural strain flexibility characteristic from the impact test data has been proposed, which is useful for structural static strain prediction and capacity evaluation. Examples of a six meter simple supported beam and a multiple-span continuous beam bridge have successfully verified the effectiveness of the proposed method. (paper)

Low velocity instrumented impact testing of four new damage tolerant carbon/epoxy composite systems

Science.gov (United States)

Lance, D. G.; Nettles, A. T.

1990-01-01

Low velocity drop weight instrumented impact testing was utilized to examine the damage resistance of four recently developed carbon fiber/epoxy resin systems. A fifth material, T300/934, for which a large data base exists, was also tested for comparison purposes. A 16-ply quasi-isotropic lay-up configuration was used for all the specimens. Force/absorbed energy-time plots were generated for each impact test. The specimens were cross-sectionally analyzed to record the damage corresponding to each impact energy level. Maximum force of impact versus impact energy plots were constructed to compare the various systems for impact damage resistance. Results show that the four new damage tolerant fiber/resin systems far outclassed the T300/934 material. The most damage tolerant material tested was the IM7/1962 fiber/resin system.

Investigation of electromagnetic launcher behavior for impact fusion. Annual report, July 1, 1983-May 1, 1984

International Nuclear Information System (INIS)

Thio, Y.C.

1984-06-01

A program to develop an ultrahigh velocity accelerator (SUVAC), based on the electromagnetic railgun accelerator concept and sponsored by the US Department of Energy, has been initiated at Westinghouse R and D Center. The program involves the construction over a 4-year period (July 1983 to June 1987) of a multi-stage railgun accelerator which has the potential of accelerating a 1-g projectile to about 30 km/s (Mach 100). The scientific objective of the program is to use the accelerator so built as the experimental apparatus to investigate the potential technical problems of accelerating macroparticles to velocity presently thought to be required to produce impact fusion. The program is part of a joint program with the University of Washington to develop the scientific and technological basis to achieve controlled thermonuclear fusion by hypervelocity impact. This report summarizes the progress made in the first year of the program. It covers work done for the period July 1, 1983 to May 1, 1984

Impact testing of polymer-filled auxetics using Split Hopkinson Pressure Bar

Czech Academy of Sciences Publication Activity Database

Fíla, T.; Zlámal, P.; Jiroušek, O.; Falta, J.; Koudelka_ml., P.; Kytýř, D.; Doktor, T.; Valach, Jaroslav

2017-01-01

Roč. 19, č. 10 (2017), č. článku 1700076. ISSN 1438-1656 R&D Projects: GA MŠk(CZ) LO1219 Keywords : bridge decks * filled polymers * filling * honeycomb structures * impact testing * mechanical testing * Poisson ratio * polyurethanes Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 2.319, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/adem.201700076/abstract

Computer-based tests: The impact of test design and problem of equivalency

Czech Academy of Sciences Publication Activity Database

Květon, Petr; Jelínek, Martin; Vobořil, Dalibor; Klimusová, H.

-, č. 23 (2007), s. 32-51 ISSN 0747-5632 R&D Projects: GA ČR(CZ) GA406/99/1052; GA AV ČR(CZ) KSK9058117 Institutional research plan: CEZ:AV0Z7025918 Keywords : Computer-based assessment * speeded test * equivalency Subject RIV: AN - Psychology Impact factor: 1.344, year: 2007

Evaluation of the Impact Resistance of Various Composite Sandwich Beams by Vibration Tests

Directory of Open Access Journals (Sweden)

Amir Shahdin

2011-01-01

Full Text Available Impact resistance of different types of composite sandwich beams is evaluated by studying vibration response changes (natural frequency and damping ratio. This experimental works will help aerospace structural engineer in assess structural integrity using classification of impact resistance of various composite sandwich beams (entangled carbon and glass fibers, honeycomb and foam cores. Low velocity impacts are done below the barely visible impact damage (BVID limit in order to detect damage by vibration testing that is hardly visible on the surface. Experimental tests are done using both burst random and sine dwell testing in order to have a better confidence level on the extracted modal parameters. Results show that the entangled sandwich beams have a better resistance against impact as compared to classical core materials.

Guidelines for conducting impact tests on shipping packages for radioactive material

International Nuclear Information System (INIS)

Mok, G.C.; Carlson, R.W.; Lu, S.C.; Fischer, L.E.

1995-09-01

Federal regulation (10 CFR Part 71) specifies a number of impact conditions (free-drop, penetration, and puncture), under which a package for the transport of radioactive materials must be tested or evaluated to demonstrate compliance with the regulation. This report is a comprehensive guide to the planning and execution of these impact tests. The report identifies the required considerations for both the design, pre-, and post-test inspections of the test model and the measurement, recording, analysis, and reporting of the test data. The report also presents reasons for the requirements, identifies the major difficulties in meeting these requirements, and suggests possible methods to overcome the difficulties. Discussed in substantial detail is the use of scale models and instrumented measurements

Personal Narratives of Genetic Testing: Expectations, Emotions, and Impact on Self and Family.

Science.gov (United States)

Anderson, Emily E; Wasson, Katherine

2015-01-01

The stories in this volume shed light on the potential of narrative inquiry to fill gaps in knowledge, particularly given the mixed results of quantitative research on patient views of and experiences with genetic and genomic testing. Published studies investigate predictors of testing (particularly risk perceptions and worry); psychological and behavioral responses to testing; and potential impact on the health care system (e.g., when patients bring DTC genetic test results to their primary care provider). Interestingly, these themes did not dominate the narratives published in this issue. Rather, these narratives included consistent themes of expectations and looking for answers; complex emotions; areas of contradiction and conflict; and family impact. More narrative research on patient experiences with genetic testing may fill gaps in knowledge regarding how patients define the benefits of testing, changes in psychological and emotional reactions to test results over time, and the impact of testing on families.

Acoustic emission measurements during impacts tests for determining ductile fracture data

International Nuclear Information System (INIS)

Richter, H.

2000-09-01

The document reports work for further development of methods and tests to obtain better information on the crack initiation toughness (J id ) under impact loading conditions, by acoustic emission measurements. The applicability of the acoustic emission tests for the given purpose was proven by instrumented Charpy tests using modified ISO-V specimens. The physical crack initiation toughness served as the reference value for reliable evaluation of the characteristic data obtained. This reference value is derived from the crack resistance curve determined by the multi-specimen cleavage fracture method combined with data from measurements of the stretching zone width. Verification of the acoustic emission-defined initiation value included a variety of tests, as e.g. additional dynamic single-specimen methods (L-COD, magnetic emission), and supplementary tests (D3PB, pendulum impact testing machine). The test materials are various steels with different strength/toughness properties. (orig./CB) [de

Test Directions as a Critical Component of Test Design: Best Practices and the Impact of Examinee Characteristics

Science.gov (United States)

Lakin, Joni M.

2014-01-01

The purpose of test directions is to familiarize examinees with a test so that they respond to items in the manner intended. However, changes in educational measurement as well as the U.S. student population present new challenges to test directions and increase the impact that differential familiarity could have on the validity of test score…

Impact ionisation mass spectrometry of polypyrrole-coated pyrrhotite microparticles

Science.gov (United States)

Hillier, Jon K.; Sternovsky, Zoltan; Armes, Steven P.; Fielding, Lee A.; Postberg, Frank; Bugiel, Sebastian; Drake, Keith; Srama, Ralf; Kearsley, Anton T.; Trieloff, Mario

2014-07-01

Cation and anion impact ionization mass spectra of polypyrrole-coated pyrrhotite cosmic dust analogue particles are analysed over a range of cosmically relevant impact speeds. Spectra with mass resolutions of 150-300 were generated by hypervelocity impacts of charged particles, accelerated to up to 37 km s-1 in a Van de Graaff electrostatic accelerator, onto a silver target plate in the Large Area Mass Analyzer (LAMA) spectrometer. Ions clearly indicative of the polypyrrole overlayer are identified at masses of 93, 105, 117, 128 and 141 u. Organic species, predominantly derived from the thin (20 nm) polypyrrole layer on the surface of the particles, dominate the anion spectra even at high (>20 km s-1) impact velocities and contribute significantly to the cation spectra at velocities lower than this. Atomic species from the pyrrhotite core (Fe and S) are visible in all spectra at impact velocities above 6 km s-1 for 56Fe+, 9 km s-1 for 32S+ and 16 km s-1 for 32S- ions. Species from the pyrrhotite core are also frequently visible in cation spectra at impact speeds at which surface ionisation is believed to dominate (Silver was confirmed as an excellent choice for the target plate of an impact ionization mass spectrometer, as it provided a unique isotope signature for many target-projectile cluster peaks at masses above 107-109 u. The affinity of Ag towards a dominant organic fragment ion (CN-) derived from fragmentation of the polypyrrole component led to molecular cluster formation. This resulted in an enhanced sensitivity to a particular particle component, which may be of great use when investigating astrobiologically relevant chemicals, such as amino acids.

Cycom 977-2 Composite Material: Impact Test Results (workshop presentation)

Science.gov (United States)

Engle, Carl; Herald, Stephen; Watkins, Casey

2005-01-01

Contents include the following: Ambient (13A) tests of Cycom 977-2 impact characteristics by the Brucenton and statistical method at MSFC and WSTF. Repeat (13A) tests of tested Cycom from phase I at MSFC to expended testing statistical database. Conduct high-pressure tests (13B) in liquid oxygen (LOX) and GOX at MSFC and WSTF to determine Cycom reaction characteristics and batch effect. Conduct expended ambient (13A) LOX test at MSFC and high-pressure (13B) testing to determine pressure effects in LOX. Expend 13B GOX database.

Acoustic emission measurement during instrumented impact tests

International Nuclear Information System (INIS)

Crostack, H.A.; Engelhardt, A.H.

1983-01-01

Results of instrumented impact tests are discussed. On the one hand the development of the loading process at the hammer tup was recorded by means of a piezoelectric transducer. This instrumentation supplied a better representation of the load versus time than the conventional strain gauges. On the other hand the different types of acoustic emission occurring during a test could be separated. The acoustic emission released at the impact of the hammer onto the specimen is of lower frequency and its spectrum is strongly decreasing with increasing frequency. Plastic deformation also emits signals of lower frequency that are of quasi-continuous character. Both signal types can be discriminated by filtering. As a consequence typical burst signal were received afterwards that can be correlated with crack propagation. Their spectra exhibit considerable portions up to about 1.9 MHz. The development in time of the burst signals points to the kind of crack propagation resp. its sequence of appearance. However, definitive comparison between load and acoustic emission should become possible, only when the disadvantages of the common load measurement can be reduced, e.g. by determining the load directly at the specimen instead of the hammer tup

Ground Testing for Hypervelocity Flow, Capabilities and Limitations

Science.gov (United States)

2010-03-29

Brisbane (T4) in Australia, see http://www.uq.edu.au/~e4dmee/t4.html, and larger ones at Göttingen in Germany (HEG), see e. g., Hannemann (2002), and...Fluids, 11:4026–4039. Hannemann , K. (2002). High-enthalpy flows in the HEG shock tunnel: Experiment and numerical rebuilding. 22nd AIAA Aerodynamic

Pendulum impact tests of wooden and steel highway guardrail posts

Science.gov (United States)

Charles J. Gatchell; Jarvis D. Michie

1974-01-01

Impact strength characteristics of southern pine, red oak, and steel highway guardrail posts were evaluated in destructive impact testing with a 4,000-pound pendulum at the Southwest Research Institute. Effects were recorded with high-speed motion-picture equipment. Comparisons were based on reactions to the point of major post failure. Major comparisons of 6x6-inch...

Results of a conventional fuel tank blunt impact test

Science.gov (United States)

2015-03-23

The Federal Railroad Administrations Office of Research : and Development is conducting research into passenger : locomotive fuel tank crashworthiness. A series of impact tests is : being conducted to measure fuel tank deformation under two : type...

Review of Evidence of Environmental Impacts of Animal Research and Testing

Directory of Open Access Journals (Sweden)

Katherine Groff

2014-06-01

Full Text Available Millions of animals are used in research and toxicity testing, including in drug, medical device, chemical, cosmetic, personal care, household, and other product sectors, but the environmental consequences are yet to be adequately addressed. Evidence suggests that their use and disposal, and the associated use of chemicals and supplies, contribute to pollution as well as adverse impacts on biodiversity and public health. The objective of this review is to examine such evidence. The review includes examinations of (1 resources used in animal research; (2 waste production in laboratories; (3 sources of pollution; (4 impacts on laboratory workers’ health; and (5 biodiversity impacts. The clear conclusion from the review is that the environmental implications of animal testing must be acknowledged, reported, and taken into account as another factor in addition to ethical and scientific reasons weighing heavily in favor of moving away from allowing and requiring animal use in research and testing.

Quantitative studies on impact resistance of reinforced concrete panels with steel liners under impact loading. Part 1: Scaled model impact tests

International Nuclear Information System (INIS)

Tsubota, H.; Kasai, Y.; Koshika, N.; Morikawa, H.; Uchida, T.; Ohno, T.; Kogure, K.

1993-01-01

In recent years, extensive analytical and experimental studies have been carried out to establish a rational structural design method for nuclear power plants against local damage caused by various external missiles. Through these studies, several techniques for improving die impact resistance of reinforced concrete slabs have been proposed. Of these techniques, attaching a thin steel liner onto the impacted and/or rear face of the slab is considered to be one of the most effective methods. Muto et. al. carried out full-scale impact tests using actual aircraft engines and reported that a thin corrugated steel liner attached to the rear face of a concrete panel has a significant effect in preventing scattering of scabbed concrete debris from the rear face of the target. Based on many experimental and analytical studies, UKAEA reported that a steel liner attached to a reinforced concrete slab improves its perforation and scabbing resistance, and Walter et. al. proposed a formula for predicting the equivalent thickness of a slab with a steel liner attached. The object of this study was to evaluate quantitatively the effect of a steel liner attached to a reinforced concrete slab in preventing local damage caused by rigid missiles. To achieve the object, extensive impact tests were carried out. This paper summarizes the results of these tests

Pedestrian headform testing: inferring performance at impact speeds and for headform masses not tested, and estimating average performance in a range of real-world conditions.

Science.gov (United States)

Hutchinson, T Paul; Anderson, Robert W G; Searson, Daniel J

2012-01-01

Tests are routinely conducted where instrumented headforms are projected at the fronts of cars to assess pedestrian safety. Better information would be obtained by accounting for performance over the range of expected impact conditions in the field. Moreover, methods will be required to integrate the assessment of secondary safety performance with primary safety systems that reduce the speeds of impacts. Thus, we discuss how to estimate performance over a range of impact conditions from performance in one test and how this information can be combined with information on the probability of different impact speeds to provide a balanced assessment of pedestrian safety. Theoretical consideration is given to 2 distinct aspects to impact safety performance: the test impact severity (measured by the head injury criterion, HIC) at a speed at which a structure does not bottom out and the speed at which bottoming out occurs. Further considerations are given to an injury risk function, the distribution of impact speeds likely in the field, and the effect of primary safety systems on impact speeds. These are used to calculate curves that estimate injuriousness for combinations of test HIC, bottoming out speed, and alternative distributions of impact speeds. The injuriousness of a structure that may be struck by the head of a pedestrian depends not only on the result of the impact test but also the bottoming out speed and the distribution of impact speeds. Example calculations indicate that the relationship between the test HIC and injuriousness extends over a larger range than is presently used by the European New Car Assessment Programme (Euro NCAP), that bottoming out at speeds only slightly higher than the test speed can significantly increase the injuriousness of an impact location and that effective primary safety systems that reduce impact speeds significantly modify the relationship between the test HIC and injuriousness. Present testing regimes do not take fully into

Permeability Testing of Impacted Composite Laminates for Use on Reusable Launch Vehicles

Science.gov (United States)

Nettles, A. T.

2001-01-01

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite, and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented, and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a nonlinear fashion for almost all the specimens tested.

Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development

Science.gov (United States)

Pereira, J. Michael; Revilock, Duane M.; Lerch, Bradley A.; Ruggeri, Charles R.

2013-01-01

One of the difficulties with developing and verifying accurate impact models is that parameters such as high strain rate material properties, failure modes, static properties, and impact test measurements are often obtained from a variety of different sources using different materials, with little control over consistency among the different sources. In addition there is often a lack of quantitative measurements in impact tests to which the models can be compared. To alleviate some of these problems, a project is underway to develop a consistent set of material property, impact test data and failure analysis for a variety of aircraft materials that can be used to develop improved impact failure and deformation models. This project is jointly funded by the NASA Glenn Research Center and the FAA William J. Hughes Technical Center. Unique features of this set of data are that all material property data and impact test data are obtained using identical material, the test methods and procedures are extensively documented and all of the raw data is available. Four parallel efforts are currently underway: Measurement of material deformation and failure response over a wide range of strain rates and temperatures and failure analysis of material property specimens and impact test articles conducted by The Ohio State University; development of improved numerical modeling techniques for deformation and failure conducted by The George Washington University; impact testing of flat panels and substructures conducted by NASA Glenn Research Center. This report describes impact testing which has been done on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade. Data from this testing will be used in validating material models developed under this program. The material

Final report on special impact tests of plutonium shipping containers description of test results

International Nuclear Information System (INIS)

Bonzon, L.L.

1977-02-01

The results from tests conducted to determine the structural response of the LLD-1, Model 1518-6M, and FL-10 plutonium shipping packages when subjected to high-speed impacts (170 to 760 ft/sec) onto unyielding, concrete, and soil targets are presented

Blunt impact tests of retired passenger locomotive fuel tanks

Science.gov (United States)

2017-08-01

The Transportation Technology Center, Inc. conducted impact tests on three locomotive fuel tanks as part of the Federal Railroad Administrations locomotive fuel tank crashworthiness improvement program. Three fuel tanks, two from EMD F40PH locomot...

Use of a 33 MJ high-energy rotary impact testing machine for investigations into material behaviour under impact loads

International Nuclear Information System (INIS)

Issler, W.

1989-01-01

To investigate material behaviour under impact loads, previously very different testing machines have been developed. One of these concepts is the rotary impact testing machine which stores rotational energy and on which a tension impact test can be performed with almost unchanged trigger speed. With this device maximum trigger speeds can be achieved by using mechanical, elastically stored or hydraulic energy. Usable sample geometries include in particular smooth or notched round or flat tensile specimen up to 30 mm in diameter and CT10 or CT15 mechanical strength test specimen, permitting a direct comparison with results from quasi-static tests. For present speeds of load application the elastic modulus of steel can be considered as being constant. For Poisson's ratio, measurements indicated changes by approximately -8% to +20%. Early tests to investigate the strain rate showed that the strain rate under purely elastic loads applied to smooth round tensile specimen is approximately 3-10 times slower than the strain rate under plastic deformation, while this ratio may have an order of magnitude of 1:100 for notched tensile specimen. Therefore it is unreasonable to indicate only one value for the strain rate as a test characterising parameter. (orig./MM) [de

Developing of impact and fatigue property test database system

International Nuclear Information System (INIS)

Park, S. J.; Jun, I.; Kim, D. H.; Ryu, W. S.

2003-01-01

The impact and fatigue characteristics database systems were constructed using the data produced from impact and fatigue test and designed to hold in common the data and programs of tensile characteristics database that was constructed on 2001 and others characteristics databases that will be constructed in future. We can easily get the basic data from the impact and fatigue characteristics database systems when we prepare the new experiment and can produce high quality result by compare the previous data. The development part must be analysis and design more specific to construct the database and after that, we can offer the best quality to customers various requirements. In this thesis, we describe the procedure about analysis, design and development of the impact and fatigue characteristics database systems developed by internet method using jsp(Java Server pages) tool

Single specimen fracture toughness determination procedure using instrumented impact test

International Nuclear Information System (INIS)

Rintamaa, R.

1993-04-01

In the study a new single specimen test method and testing facility for evaluating dynamic fracture toughness has been developed. The method is based on the application of a new pendulum type instrumented impact tester equipped with and optical crack mouth opening displacement (COD) extensometer. The fracture toughness measurement technique uses the Double Displacement Ratio (DDR) method, which is based on the assumption that the specimen is deformed as two rigid arms that rotate around an apparent centre of rotation. This apparent moves as the crack grows, and the ratio of COD versus specimen displacement changes. As a consequence the onset ductile crack initiation can be detected on the load-displacement curve. Thus, an energy-based fracture toughness can be calculated. In addition the testing apparatus can use specimens with the Double ligament size as compared with the standard Charpy specimen which makes the impact testing more appropriate from the fracture mechanics point of view. The novel features of the testing facility and the feasibility of the new DDR method has been verified by performing an extensive experimental and analytical study. (99 refs., 91 figs., 27 tabs.)

A New Energy Source for Organic Synthesis in Europa's Surface Ice

Science.gov (United States)

Borucki, Jerome G.; Khare, Bishun; Cruikshank, Dale P.; DeVincenzi, D. (Technical Monitor)

2002-01-01

Colored regions on Jupiter's satellite Europa and other icy bodies in the outer Solar System may be contaminated by organic macromolecular solid material that is produced when surface ices are exposed to electrical energy. Hypervelocity meteorite impacts and fracture release tidal and tectonic stresses in icy crusts in the form of electrical discharges, which provide the energy for in situ synthesis of the organic solids. We report measurements of electrical discharge, light emission, and magnetic phenomena in hypervelocity impacts into ice with projectiles with V approx. 5 km/s. Part of the projectile's kinetic energy is converted into electrical potential, while the mechanical disruption of the impact also releases stress energy as light, heat, electrical, and magnetic fields as secondary emissions. These newly recognized energy sources suggest that the dark material in the area of impact craters are tholins generated from the energy of the impacts and that well up from the fracture zone. Large pools of liquid water would persist under the meteorite crater for thousands of years, with the potential for prebiotic chemistry to take place at an accelerated rate due to energy pumped in from the secondary emissions.

Machine for development impact tests in sports seats and similar

International Nuclear Information System (INIS)

Gonçalves, R M

2015-01-01

This paper describes the stages of development of a machine to perform impact tests in sport seats, seats for spectators and multiple seats. This includes reviews and recommendations for testing laboratories that have needs similar to the laboratory where unfolded this process.The machine was originally developed seeking to meet certain impact tests in accordance with the NBR15925 standards; 15878 and 16031. The process initially included the study of the rules and the election of the tests for which the machine could be developed and yet all reports and outcome of interaction with service providers and raw materials.For operating facility, it was necessary to set entirely the machine control, which included the concept of dialogue with operator, the design of the menu screens and the procedures for submission and registration of results. To ensure reliability in the process, the machine has been successfully calibrated according to the requirements of the Brazilian network of calibration.The criticism to this enterprise covers the technical and economic aspects involved and points out the main obstacles that were needed to overcome. (paper)

An assessment of testing requirement impacts on nuclear thermal propulsion ground test facility design

International Nuclear Information System (INIS)

Shipers, L.R.; Ottinger, C.A.; Sanchez, L.C.

1993-01-01

Programs to develop solid core nuclear thermal propulsion (NTP) systems have been under way at the Department of Defense (DoD), the National Aeronautics and Space Administration (NASA), and the Department of Energy (DOE). These programs have recognized the need for a new ground test facility to support development of NTP systems. However, the different military and civilian applications have led to different ground test facility requirements. The Department of Energy (DOE) in its role as landlord and operator of the proposed research reactor test facilities has initiated an effort to explore opportunities for a common ground test facility to meet both DoD and NASA needs. The baseline design and operating limits of the proposed DoD NTP ground test facility are described. The NASA ground test facility requirements are reviewed and their potential impact on the DoD facility baseline is discussed

Tests for determining impact resistance and strength of glass used for nuclear waste disposal

International Nuclear Information System (INIS)

Bunnell, L.R.

1979-05-01

Tests are described for determining the impact resistance (Section A) and static tensile strength (Section B) of glasses containing simulated or actual nuclear wastes. This report describes the development and use of these tests to rank different glasses, to assess effects of devitrification, and to examine the effect of impact energy on resulting surface area. For clarity this report is divided into two sections, Impact Resistance and Tensile Strength

HVI Ballistic Limit Charaterization of Fused Silica Thermal Pane

Science.gov (United States)

Bohl, William E.; Miller, Joshua E.; Christiansen, Eric L.; Deighton, Kevin.; Davis, Bruce

2015-01-01

The Orion spacecraft's windows are exposed to the micrometeroid and orbital debris (MMOD) space environments while in space as well as the Earth entry environment at the mission's conclusion. The need for a low-mass spacecraft window design drives the need to reduce conservatism when assessing the design for loss of crew due to MMOD impact and subsequent Earth entry. Therefore, work is underway at NASA and Lockheed Martin to improve characterization of the complete penetration ballistic limit of an outer fused silica thermal pane. Hypervelocity impact tests of the window configuration at up to 10 km/s and hydrocode modeling have been performed with a variety of projectile materials to enable refinement of the fused silica ballistic limit equation.

Measuring High Speed Deformation for Space Applications

Science.gov (United States)

Wentzel, Daniel

2014-01-01

PDV (Photonic Doppler Velocimetry) has proven to be a reliable and versatile technique to observe rapid deformation of frangible joints. It will be a valuable technique in order to understand the physics of two-stage light gas guns and the material response to hypervelocity impact.

Comparative Testing for Corporate Impact Assessment Tools

DEFF Research Database (Denmark)

Farsang, Andrea; Reisch, Lucia A.

of our study are: poverty, water and sanitation, education, food and agriculture, climate change, and human rights in three industries, namely: footwear, coffee, and paper and pulp. The paper develops a protocol for the selection and quantification of indicators that can be used in selecting...... the appropriate tools for measuring impacts in the selected sectors on SDGs. Background: In the Global Value Project, a long list of indicators was compiled covering the main thematic areas and challenges of sustainability. In a second step, this long list was reduced using predefined criteria as well as other...... criteria, such as the feasibility and scalability of different tools. As a result, a protocol was developed to help compare the different tools that measure corporate impact and to interpret the results in relation to the SDGs. The protocol was pre-tested with a limited number of tools in two case studies...

Mesoscopic analyses of porous concrete under static compression and drop weight impact tests

DEFF Research Database (Denmark)

Agar Ozbek, A.S.; Pedersen, R.R.; Weerheijm, J.

2008-01-01

was considered as a four-phase material incorporating aggregates, bulk cement paste, interfacial transition zones and meso-size air pores. The stress-displacement relations obtained from static compression tests, the stress values, and the corresponding damage levels provided by the drop weight impact tests were......The failure process in highly porous concrete was analyzed experimentally and numerically. A triaxial visco-plastic damage model and a mesoscale representation of the material composition were considered to reproduce static compression and drop weight impact tests. In the mesoscopic model, concrete...

Neurocognitive performance and symptom profiles of Spanish-speaking Hispanic athletes on the ImPACT test.

Science.gov (United States)

Ott, Summer; Schatz, Philip; Solomon, Gary; Ryan, Joseph J

2014-03-01

This study documented baseline neurocognitive performance of 23,815 athletes on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test. Specifically, 9,733 Hispanic, Spanish-speaking athletes who completed the ImPACT test in English and 2,087 Hispanic, Spanish-speaking athletes who completed the test in Spanish were compared with 11,955 English-speaking athletes who completed the test in English. Athletes were assigned to age groups (13-15, 16-18). Results revealed a significant effect of language group (p Spanish-speaking athletes completing the test in Spanish scored more poorly than Spanish-speaking and English-speaking athletes completing the test in English, on all Composite scores and Total Symptom scores. Spanish-speaking athletes completing the test in English also performed more poorly than English-speaking athletes completing the test in English on three Composite scores. These differences in performance and reported symptoms highlight the need for caution in interpreting ImPACT test data for Hispanic Americans.

Dynamic impact testing of hedgehog spines using a dual-arm crash pendulum.

Science.gov (United States)

Swift, Nathan B; Hsiung, Bor-Kai; Kennedy, Emily B; Tan, Kwek-Tze

2016-08-01

Hedgehog spines are a potential model for impact resistant structures and material. While previous studies have examined static mechanical properties of individual spines, actual collision tests on spines analogous to those observed in the wild have not previously been investigated. In this study, samples of roughly 130 keratin spines were mounted vertically in thin substrates to mimic the natural spine layout on hedgehogs. A weighted crash pendulum was employed to induce and measure the effects of repeated collisions against samples, with the aim to evaluate the influence of various parameters including humidity effect, impact energy, and substrate hardness. Results reveal that softer samples-due to humidity conditioning and/or substrate material used-exhibit greater durability over multiple impacts, while the more rigid samples exhibit greater energy absorption performance at the expense of durability. This trend is exaggerated during high-energy collisions. Comparison of the results to baseline tests with industry standard impact absorbing foam, wherein the spines exhibit similar energy absorption, verifies the dynamic impact absorption capabilities of hedgehog spines and their candidacy as a structural model for engineered impact technology. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Physical Understanding of the Use of Coatings to Mitigate Hypervelocity Gouging Considering Real Test Sled Dimensions

National Research Council Canada - National Science Library

Szmerekovsky, Andrew

2004-01-01

A dimensional analysis with accompanying numerical investigation is conducted. A simplified model of the real test sled is created that allows test sled dimensions to be converted to a numerical model for analysis...

Budget impact analysis of chronic kidney disease mass screening test in Japan.

Science.gov (United States)

Kondo, Masahide; Yamagata, Kunihiro; Hoshi, Shu-Ling; Saito, Chie; Asahi, Koichi; Moriyama, Toshiki; Tsuruya, Kazuhiko; Konta, Tsuneo; Fujimoto, Shouichi; Narita, Ichiei; Kimura, Kenjiro; Iseki, Kunitoshi; Watanabe, Tsuyoshi

2014-12-01

Our recently published cost-effectiveness study on chronic kidney disease mass screening test in Japan evaluated the use of dipstick test, serum creatinine (Cr) assay or both in specific health checkup (SHC). Mandating the use of serum Cr assay additionally, or the continuation of current policy mandating dipstick test only was found cost-effective. This study aims to examine the affordability of previously suggested reforms. Budget impact analysis was conducted assuming the economic model would be good for 15 years and applying a population projection. Costs expended by social insurers without discounting were counted as budgets. Annual budget impacts of mass screening compared with do-nothing scenario were calculated as ¥79-¥-1,067 million for dipstick test only, ¥2,505-¥9,235 million for serum Cr assay only and ¥2,517-¥9,251 million for the use of both during a 15-year period. Annual budget impacts associated with the reforms were calculated as ¥975-¥4,129 million for mandating serum Cr assay in addition to the currently used mandatory dipstick test, and ¥963-¥4,113 million for mandating serum Cr assay only and abandoning dipstick test. Estimated values associated with the reform from ¥963-¥4,129 million per year over 15 years are considerable amounts of money under limited resources. The most impressive finding of this study is the decreasing additional expenditures in dipstick test only scenario. This suggests that current policy which mandates dipstick test only would contain medical care expenditure.

Testing and injury potential analysis of rollovers with narrow object impacts.

Science.gov (United States)

Meyer, Steven E; Forrest, Stephen; Herbst, Brian; Hayden, Joshua; Orton, Tia; Sances, Anthony; Kumaresan, Srirangam

2004-01-01

Recent statistics highlight the significant risk of serious and fatal injuries to occupants involved in rollover collisions due to excessive roof crush. The government has reported that in 2002. Sports Utility Vehicle rollover related fatalities increased by 14% to more than 2400 annually. 61% of all SUV fatalities included rollovers [1]. Rollover crashes rely primarily upon the roof structures to maintain occupant survival space. Frequently these crashes occur off the travel lanes of the roadway and, therefore, can include impacts with various types of narrow objects such as light poles, utility poles and/or trees. A test device and methodology is presented which facilitates dynamic, repeatable rollover impact evaluation of complete vehicle roof structures with such narrow objects. These tests allow for the incorporation of Anthropomorphic Test Dummies (ATDs) which can be instrumented to measure accelerations, forces and moments to evaluate injury potential. High-speed video permits for detailed analysis of occupant kinematics and evaluation of injury causation. Criteria such as restraint performance, injury potential, survival space and the effect of roof crush associated with various types of design alternatives, countermeasures and impact circumstances can also be evaluated. In addition to presentation of the methodology, two representative vehicle crash tests are also reported. Results indicated that the reinforced roof structure significantly reduced the roof deformation compared to the production roof structure.

High-silicon 238PuO2 fuel characterization study: Half module impact tests

International Nuclear Information System (INIS)

Reimus, M.A.H.

1997-01-01

The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of [sup 238]Pu decay to an array of thermoelectric elements. The modular GPHS design was developed to address both survivability during launch abort and return from orbit. Previous testing conducted in support of the Galileo and Ulysses missions documented the response of GPHSs to a variety of fragment- impact, aging, atmospheric reentry, and Earth-impact conditions. The evaluations documented in this report are part of an ongoing program to determine the effect of fuel impurities on the response of the heat source to conditions baselined during the Galileo/Ulysses test program. In the first two tests in this series, encapsulated GPHS fuel pellets containing high levels of silicon were aged, loaded into GPHS module halves, and impacted against steel plates. The results show no significant differences between the response of these capsules and the behavior of relatively low-silicon fuel pellets tested previously

The psychological impact of genetic testing on parents.

Science.gov (United States)

Dinc, Leyla; Terzioglu, Fusun

2006-01-01

The aim of this descriptive study was to explore the psychological impact of genetic testing on parents whose children have been referred for genetic testing. Genetic tests enable individuals to be informed about their health status and to have the opportunity of early diagnosis and treatment of their diseases. However undergoing genetic testing and receiving a positive test result may also cause stress and anxiety. This descriptive study was carried out at the genetic departments of two university hospitals in Ankara. The sample of this study consisted of 128 individuals whose children have been referred for chromosomal analysis. Data were collected through using a semi-structured interview method with a data collection form and the anxiety inventory and analysed using the percentages and independent samples t-test. The majority of our participants experienced distress before genetic testing. Their general trait anxiety score before receiving the test results was 47.38, and following the test results the state anxiety score was 50.65. Having a previous child with an abnormality, a positive test result, and being a mother elevated the anxiety of individuals. This paper supports the findings of previous studies, which indicated that genetic test results might lead to anxiety in individuals and reveals the importance of genetic counselling. As the results of this study indicated, genetic testing causes distress and anxiety in individuals. Nurses can play an important role in minimizing anxiety of parents whose children undergo genetic testing by providing information about genetic testing and by taking part in the counselling process.

A 900 electrostatic prism for microparticle beam steering on a 2 MV van der Graaff dust accelerator

International Nuclear Information System (INIS)

Dixon, D.G.; Clarke, C.D.; McDonnell, J.A.M.; Dickason, R.E.; Flavill, R.P.

1984-01-01

The design and construction of a 90 0 electrostatic prism is described. The device is used to deflect hypervelocity dust particles produced in a horizontal van der Graaff accelerator to simulate micrometeoroid impacts on dusty lunar and asteroidal surfaces where vertical incidence must be provided. (author)

LDEF- 69 Months in Space. Second Post-Retrieval Symposium, Part 2

Science.gov (United States)

1992-06-01

for Craters Formed by High-Velocity Projectiles." Hypervelocity Impact, 3rd Symposium, Armour Research Foundation of Illinois Inst. of Technology...The crater visible in Figure 1 c is substantially smoother than either of the previous features and is draped with a thin melt layer containing

Free Flight Ground Testing of ADEPT in Advance of the Sounding Rocket One Flight Experiment

Science.gov (United States)

Smith, B. P.; Dutta, S.

2017-01-01

The Adaptable Deployable Entry and Placement Technology (ADEPT) project will be conducting the first flight test of ADEPT, titled Sounding Rocket One (SR-1), in just two months. The need for this flight test stems from the fact that ADEPT's supersonic dynamic stability has not yet been characterized. The SR-1 flight test will provide critical data describing the flight mechanics of ADEPT in ballistic flight. These data will feed decision making on future ADEPT mission designs. This presentation will describe the SR-1 scientific data products, possible flight test outcomes, and the implications of those outcomes on future ADEPT development. In addition, this presentation will describe free-flight ground testing performed in advance of the flight test. A subsonic flight dynamics test conducted at the Vertical Spin Tunnel located at NASA Langley Research Center provided subsonic flight dynamics data at high and low altitudes for multiple center of mass (CoM) locations. A ballistic range test at the Hypervelocity Free Flight Aerodynamics Facility (HFFAF) located at NASA Ames Research Center provided supersonic flight dynamics data at low supersonic Mach numbers. Execution and outcomes of these tests will be discussed. Finally, a hypothesized trajectory estimate for the SR-1 flight will be presented.

Rapid impact testing for quantitative assessment of large populations of bridges

Science.gov (United States)

Zhou, Yun; Prader, John; DeVitis, John; Deal, Adrienne; Zhang, Jian; Moon, Franklin; Aktan, A. Emin

2011-04-01

Although the widely acknowledged shortcomings of visual inspection have fueled significant advances in the areas of non-destructive evaluation and structural health monitoring (SHM) over the last several decades, the actual practice of bridge assessment has remained largely unchanged. The authors believe the lack of adoption, especially of SHM technologies, is related to the 'single structure' scenarios that drive most research. To overcome this, the authors have developed a concept for a rapid single-input, multiple-output (SIMO) impact testing device that will be capable of capturing modal parameters and estimating flexibility/deflection basins of common highway bridges during routine inspections. The device is composed of a trailer-mounted impact source (capable of delivering a 50 kip impact) and retractable sensor arms, and will be controlled by an automated data acquisition, processing and modal parameter estimation software. The research presented in this paper covers (a) the theoretical basis for SISO, SIMO and MIMO impact testing to estimate flexibility, (b) proof of concept numerical studies using a finite element model, and (c) a pilot implementation on an operating highway bridge. Results indicate that the proposed approach can estimate modal flexibility within a few percent of static flexibility; however, the estimated modal flexibility matrix is only reliable for the substructures associated with the various SIMO tests. To overcome this shortcoming, a modal 'stitching' approach for substructure integration to estimate the full Eigen vector matrix is developed, and preliminary results of these methods are also presented.

Advances in impact resistance testing for explosion-proof electrical equipment

Directory of Open Access Journals (Sweden)

Pasculescu Vlad Mihai

2017-01-01

Full Text Available The design, construction and exploitation of electrical equipment intended to be used in potentially explosive atmospheres presents a series of difficulties. Therefore, the approach of these phases requires special attention concerning technical, financial and occupational health and safety aspects. In order for them not to generate an ignition source for the explosive atmosphere, such equipment have to be subjected to a series of type tests aiming to decrease the explosion risk in technological installations which operate in potentially explosive atmospheres. Explosion protection being a concern of researchers and authorities worldwide, testing and certification of explosion-proof electrical equipment, required for their conformity assessment, are extremely important, taking into account the unexpected explosion hazard due to potentially explosive atmospheres, risk which has to be minimized in order to ensure the occupational health and safety of workers, for preventing material losses and for decreasing the environmental pollution. Besides others, one of the type tests, which shall be applied, for explosion-proof electrical equipment is the impact resistance test, described in detail in EN 60079 which specifies the general requirements for construction, testing and marking of electrical equipment and Ex components intended for use in explosive atmospheres. This paper presents an analysis on the requirements of the impact resistance test for explosion-proof electrical equipment and on the possibilities to improve this type of test, by making use of modern computer simulation tools based on finite element analysis, techniques which are widely used nowadays in the industry and for research purposes.

Utility of the ImPACT test with deaf adolescents.

Science.gov (United States)

Reesman, Jennifer; Pineda, Jill; Carver, Jenny; Brice, Patrick J; Zabel, T Andrew; Schatz, Philip

2016-02-01

The goals of the study included empirical examination of the utility of the Immediate and Post-Concussion Assessment and Cognitive Testing (ImPACT) test with adolescents who are deaf or hard-of-hearing and to investigate patterns of performance at baseline that may arise in the assessment of this population. Baseline assessment of student-athletes has been conducted on a widespread scale with focus on performance of typically developing student-athletes and some clinical groups, though to date no studies have examined adolescents who are deaf or hard-of-hearing. Retrospective and de-identified ImPACT baseline test used with deaf and hard-of-hearing high-school student-athletes (N = 143; 66% male, mean age = 16.11) was examined. Review indicated significant differences in some composite scores between the deaf and hard-of-hearing group and hearing normative comparisons. A possible marker of task misunderstanding was identified to occur more frequently within the deaf and hard-of-hearing sample (13% in deaf sample vs. .31% in hearing sample). Results may provide support for the consideration and use of additional measures to ensure comprehension of task demands when considering this tool for use with deaf and hard-of-hearing adolescents.

The WRAIR projectile concussive impact model of mild traumatic brain injury: re-design, testing and preclinical validation.

Science.gov (United States)

Leung, Lai Yee; Larimore, Zachary; Holmes, Larry; Cartagena, Casandra; Mountney, Andrea; Deng-Bryant, Ying; Schmid, Kara; Shear, Deborah; Tortella, Frank

2014-08-01

The WRAIR projectile concussive impact (PCI) model was developed for preclinical study of concussion. It represents a truly non-invasive closed-head injury caused by a blunt impact. The original design, however, has several drawbacks that limit the manipulation of injury parameters. The present study describes engineering advancements made to the PCI injury model including helmet material testing, projectile impact energy/head kinematics and impact location. Material testing indicated that among the tested materials, 'fiber-glass/carbon' had the lowest elastic modulus and yield stress for providing an relative high percentage of load transfer from the projectile impact, resulting in significant hippocampal astrocyte activation. Impact energy testing of small projectiles, ranging in shape and size, showed the steel sphere produced the highest impact energy and the most consistent impact characteristics. Additional tests confirmed the steel sphere produced linear and rotational motions on the rat's head while remaining within a range that meets the criteria for mTBI. Finally, impact location testing results showed that PCI targeted at the temporoparietal surface of the rat head produced the most prominent gait abnormalities. Using the parameters defined above, pilot studies were conducted to provide initial validation of the PCI model demonstrating quantifiable and significant increases in righting reflex recovery time, axonal damage and astrocyte activation following single and multiple concussions.

Horizontal impact testing of quarter scale flasks using masonry targets

International Nuclear Information System (INIS)

Tufton, E.P.S.

1985-01-01

The programme leading up to the Train Crash Demonstration included investigation of flask impacts, in horizontal motion, against masonry targets representing abutment structures. An outline is given of a series of eight tests, of which five are described in detail. All the tests used quarter-scale flasks, and the design and construction of the appropriate brick and stone masonry targets is described. A summary of results is given in terms of damage to the model flask compared with the more severe damage seen in regulatory drop tests. (author)

Numerical simulation of impact tests on reinforced concrete beams

International Nuclear Information System (INIS)

Jiang, Hua; Wang, Xiaowo; He, Shuanhai

2012-01-01

Highlights: ► Predictions using advanced concrete model compare well with the impact test results. ► Several important behavior of concrete is discussed. ► Two mesh ways incorporating rebar into concrete mesh is also discussed. ► Gives a example of using EPDC model and references to develop new constitutive models. -- Abstract: This paper focuses on numerical simulation of impact tests of reinforced concrete (RC) beams by the LS-DYNA finite element (FE) code. In the FE model, the elasto-plastic damage cap (EPDC) model, which is based on continuum damage mechanics in combination with plasticity theory, is used for concrete, and the reinforcement is assumed to be elasto-plastic. The numerical results compares well with the experimental values reported in the literature, in terms of impact force history, mid-span deflection history and crack patterns of RC beams. By comparing the numerical and experimental results, several important behavior of concrete material is investigated, which includes: damage variable to describe the strain softening section of stress–strain curve; the cap surface to describe the plastic volume change; the shape of the meridian and deviatoric plane to describe the yield surface as well as two methods of incorporating rebar into concrete mesh. This study gives a good example of using EPDC model and can be utilized for the development new constitutive models for concrete in future.

On protection of freedom's solar dynamic radiator from the orbital debris environment. Part 2

International Nuclear Information System (INIS)

Rhatigan, J.L.

1992-01-01

In this paper, recent progress to better understand the environmental threat of micrometeoroid and space debris to the solar dynamic radiator for the Space Station Freedom power system is reported. The objective was to define a design which would perform to survivability requirements over the expected lifetime of the radiator. A previous paper described the approach developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeoroid and space debris impacts. Preliminary analyses were presented to quantify the solar dynamic radiator survivability. These included the type of particle and particle population expected to defeat the radiator bumpering. Results of preliminary hypervelocity impact (HVI) testing performed on radiator panel samples were also presented. This paper presents results of a more extensive test program undertaken to further define the response of the solar dynamic radiator to HVI. Tests were conducted on representative radiator panels (under ambient, nonoperating conditions) over a range of particle size, particle density, impact angle, and impact velocity. Target parameters were also varied. Data indicate that analytical penetration predictions are conservative (i.e., pessimistic) for the specific configuration of the solar dynamic radiator. Test results are used to define more rigorously the solar dynamic radiator reliability with respect to HVI. Test data, analyses, and survivability results are presented

Soft projectile impacts analysis on thin reinforced concrete slabs: Tests, modelling and simulations

International Nuclear Information System (INIS)

Pontiroli, C.; Rouquand, A.; Daudeville, L.; Baroth, J.

2012-01-01

Numerical simulations of reinforced concrete structures subjected to high velocity impacts and explosions remain a difficult task today. For 10 years and more now, the CEA-Gramat has maintained a continuous research effort with the help of different French universities in order to overcome encountered difficulties in modelling the behaviour of concrete structures under severe loading. To get more data on aircraft impact problems and then validate numerical models, soft projectile impacts tests at small scale on thin reinforced concrete slabs has been carried out at CEA-Gramat. Numerical simulations of these tests have been carried out and compared with experimental results to validate our numerical approach. (authors)

Target Soil Impact Verification: Experimental Testing and Kayenta Constitutive Modeling.

Energy Technology Data Exchange (ETDEWEB)

Broome, Scott Thomas [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Flint, Gregory Mark [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Dewers, Thomas [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Newell, Pania [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-11-01

This report details experimental testing and constitutive modeling of sandy soil deformation under quasi - static conditions. This is driven by the need to understand constitutive response of soil to target/component behavior upon impact . An experimental and constitutive modeling program was followed to determine elastic - plastic properties and a compressional failure envelope of dry soil . One hydrostatic, one unconfined compressive stress (UCS), nine axisymmetric compression (ACS) , and one uniaxial strain (US) test were conducted at room temperature . Elastic moduli, assuming isotropy, are determined from unload/reload loops and final unloading for all tests pre - failure and increase monotonically with mean stress. Very little modulus degradation was discernable from elastic results even when exposed to mean stresses above 200 MPa . The failure envelope and initial yield surface were determined from peak stresses and observed onset of plastic yielding from all test results. Soil elasto - plastic behavior is described using the Brannon et al. (2009) Kayenta constitutive model. As a validation exercise, the ACS - parameterized Kayenta model is used to predict response of the soil material under uniaxial strain loading. The resulting parameterized and validated Kayenta model is of high quality and suitable for modeling sandy soil deformation under a range of conditions, including that for impact prediction.

Crash test rating and likelihood of major thoracoabdominal injury in motor vehicle crashes: the new car assessment program side-impact crash test, 1998-2010.

Science.gov (United States)

Figler, Bradley D; Mack, Christopher D; Kaufman, Robert; Wessells, Hunter; Bulger, Eileen; Smith, Thomas G; Voelzke, Bryan

2014-03-01

The National Highway Traffic Safety Administration's New Car Assessment Program (NCAP) implemented side-impact crash testing on all new vehicles since 1998 to assess the likelihood of major thoracoabdominal injuries during a side-impact crash. Higher crash test rating is intended to indicate a safer car, but the real-world applicability of these ratings is unknown. Our objective was to determine the relationship between a vehicle's NCAP side-impact crash test rating and the risk of major thoracoabdominal injury among the vehicle's occupants in real-world side-impact motor vehicle crashes. The National Automotive Sampling System Crashworthiness Data System contains detailed crash and injury data in a sample of major crashes in the United States. For model years 1998 to 2010 and crash years 1999 to 2010, 68,124 occupants were identified in the Crashworthiness Data System database. Because 47% of cases were missing crash severity (ΔV), multiple imputation was used to estimate the missing values. The primary predictor of interest was the occupant vehicle's NCAP side-impact crash test rating, and the outcome of interest was the presence of major (Abbreviated Injury Scale [AIS] score ≥ 3) thoracoabdominal injury. In multivariate analysis, increasing NCAP crash test rating was associated with lower likelihood of major thoracoabdominal injury at high (odds ratio [OR], 0.8; 95% confidence interval [CI], 0.7-0.9; p NCAP side-impact crash test rating is associated with a lower likelihood of major thoracoabdominal trauma. Epidemiologic study, level III.

Hybrid composite laminates reinforced with Kevlar/carbon/glass woven fabrics for ballistic impact testing.

Science.gov (United States)

Randjbaran, Elias; Zahari, Rizal; Jalil, Nawal Aswan Abdul; Majid, Dayang Laila Abang Abdul

2014-01-01

Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

Hybrid Composite Laminates Reinforced with Kevlar/Carbon/Glass Woven Fabrics for Ballistic Impact Testing

Directory of Open Access Journals (Sweden)

Elias Randjbaran

2014-01-01

Full Text Available Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

Standard Test Method for Determining Resistance of Photovoltaic Modules to Hail by Impact with Propelled Ice Balls

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This test method provides a procedure for determining the ability of photovoltaic modules to withstand impact forces of falling hail. Propelled ice balls are used to simulate falling hailstones. 1.2 This test method defines test specimens and methods for mounting specimens, specifies impact locations on each test specimen, provides an equation for determining the velocity of any size ice ball, provides a method for impacting the test specimens with ice balls, provides a method for determining changes in electrical performance, and specifies parameters that must be recorded and reported. 1.3 This test method does not establish pass or fail levels. The determination of acceptable or unacceptable levels of ice ball impact resistance is beyond the scope of this test method. 1.4 The size of the ice ball to be used in conducting this test is not specified. This test method can be used with various sizes of ice balls. 1.5 This test method may be applied to concentrator and nonconcentrator modules. 1.6 The v...

Ballistic Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development

Science.gov (United States)

Pereira, J. Michael; Revilock, Duane M.; Ruggeri, Charles R.; Emmerling, William C.; Altobelli, Donald J.

2012-01-01

An experimental program is underway to develop a consistent set of material property and impact test data, and failure analysis, for a variety of materials that can be used to develop improved impact failure and deformation models. Unique features of this set of data are that all material property information and impact test results are obtained using identical materials, the test methods and procedures are extensively documented and all of the raw data is available. This report describes ballistic impact testing which has been conducted on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade.

A semiautomated computer-interactive dynamic impact testing system

International Nuclear Information System (INIS)

Alexander, D.J.; Nanstad, R.K.; Corwin, W.R.; Hutton, J.T.

1989-01-01

A computer-assisted semiautomated system has been developed for testing a variety of specimen types under dynamic impact conditions. The primary use of this system is for the testing of Charpy specimens. Full-, half-, and third-size specimens have been tested, both in the lab and remotely in a hot cell for irradiated specimens. Specimens are loaded into a transfer device which moves the specimen into a chamber, where a hot air gun is used to heat the specimen, or cold nitrogen gas is used for cooling, as required. The specimen is then quickly transferred from the furnace to the anvils and then broken. This system incorporates an instrumented tup to determine the change in voltage during the fracture process. These data are analyzed by the computer system after the test is complete. The voltage-time trace is recorded with a digital oscilloscope, transferred to the computer, and analyzed. The analysis program incorporates several unique features. It interacts with the operator and identifies the maximum voltage during the test, the amount of rapid fracture during the test (if any), and the end of the fracture process. The program then calculates the area to maximum voltage and the total area under the voltage-time curve. The data acquisition and analysis part of the system can also be used to conduct other dynamic testing. Dynamic tear and precracked specimens can be tested with an instrumented tup and analyzed in a similar manner. 3 refs., 7 figs

Comparison of Space Debris Environment Models: ORDEM2000, MASTER-2001, MASTER-2005 and MASTER-2009

OpenAIRE

Kanemitsu, Yuki; 赤星, 保浩; Akahoshi, Yasuhiro; 鳴海, 智博; Narumi, Tomohiro; Faure, Pauline; 松本, 晴久; Matsumoto, Haruhisa; 北澤, 幸人; Kitazawa, Yukihito

2012-01-01

Hypervelocity impact by space debris on spacecraft is one of the most important issues for space development and operation, especially considering the growing amount of space debris in recent years. It is therefore important for spacecraft design to evaluate the impact risk by using environment models. In this paper, the authors compared the results of the debris impact flux in low Earth orbit, as calculated by four debris environment engineering models -NASA's ORDEM2000 and ESA's MASTER-2001...

Lost Impacts (Invited)

Science.gov (United States)

Schultz, P. H.; Stickle, A. M.

2009-12-01

The absence of a clearly identified crater (or craters) for the proposed YDB impact has raised questions concerning the reality of such an event. Geologic studies have identified impact deposits well before recognizing a causative crater (e.g., Chicxulub and Chesapeake Bay); some have yet to be discovered (e.g., Australasian tektite strewnfields). The absence of a crater, therefore, cannot be used as an argument against the reality of the YDB impact (and its possible consequences). The study here addresses how a large on-land impact during the late Pleistocene or early Holocene could avoid easy detection today. It does not argue the case for a YDB impact, since such evidence must come from the rock record. During the late Pleistocene, the receding Laurentide ice sheet still covered a significant portion of Canada. While a large (1km) body impacting vertically (90°) would penetrate such a low-impedance ice layer and excavate the substrate, an oblique impact couples more of its energy into the surface layer, thereby partially shielding the substrate. Three approaches address the effectiveness of this flak-jacket effect. First, hypervelocity impact experiments at the NASA Ames Vertical Gun Range investigated the effectiveness of low-impedance layers of different thicknesses for mitigating substrate damage. Second, selected experiments were compared with hydrocode models (see Stickle and Schultz, this volume) and extended to large scales. Third, comparisons were made with relict craters found in eroding sediment and ice covers on Mars. Oblique impacts (30 degrees) into soft particulates (no. 24 sand) covering a solid substrate (aluminum) have no effect on the final crater diameter for layer thicknesses exceeding a projectile diameter and result in only plastic deformation in the substrate. In contrast, a vertical impact requires a surface layer at least 3 times the projectile diameter to achieve the same diameter (with significant substrate damage). Oblique impacts

An unusual white dwarf star may be a surviving remnant of a subluminous Type Ia supernova

Czech Academy of Sciences Publication Activity Database

Vennes, Stephane; Nemeth, P.; Kawka, Adela; Thorstensen, J.R.; Khalack, V.; Ferrario, L.; Alper, E.H.

2017-01-01

Roč. 357, č. 6352 (2017), s. 680-683 ISSN 0036-8075 R&D Projects: GA ČR GA15-15943S Institutional support: RVO:67985815 Keywords : evolution * model * hypervelocity Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 37.205, year: 2016

Experimental impact testing and analysis of composite fan cases

Science.gov (United States)

Vander Klok, Andrew Joe

For aircraft engine certification, one of the requirements is to demonstrate the ability of the engine to withstand a fan blade-out (FBO) event. A FBO event may be caused by fatigue failure of the fan blade itself or by impact damage of foreign objects such as bird strike. An un-contained blade can damage flight critical engine components or even the fuselage. The design of a containment structure is related to numerous parameters such as the blade tip speed; blade material, size and shape; hub/tip diameter; fan case material, configuration, rigidity, etc. To investigate all parameters by spin experiments with a full size rotor assembly can be prohibitively expensive. Gas gun experiments can generate useful data for the design of engine containment cases at much lower costs. To replicate the damage modes similar to that on a fan case in FBO testing, the gas gun experiment has to be carefully designed. To investigate the experimental procedure and data acquisition techniques for FBO test, a low cost, small spin rig was first constructed. FBO tests were carried out with the small rig. The observed blade-to-fan case interactions were similar to those reported using larger spin rigs. The small rig has the potential in a variety of applications from investigating FBO events, verifying concept designs of rotors, to developing spin testing techniques. This rig was used in the developments of the notched blade releasing mechanism, a wire trigger method for synchronized data acquisition, high speed video imaging and etc. A relationship between the notch depth and the release speed was developed and verified. Next, an original custom designed spin testing facility was constructed. Driven by a 40HP, 40,000rpm air turbine, the spin rig is housed in a vacuum chamber of phi72inx40in (1829mmx1016mm). The heavily armored chamber is furnished with 9 viewports. This facility enables unprecedented investigations of FBO events. In parallel, a 15.4ft (4.7m) long phi4.1inch (105mm

The impact of cognitive testing on the welfare of group housed primates.

Directory of Open Access Journals (Sweden)

Jamie Whitehouse

Full Text Available Providing cognitive challenges to zoo-housed animals may provide enriching effects and subsequently enhance their welfare. Primates may benefit most from such challenges as they often face complex problems in their natural environment and can be observed to seek problem solving opportunities in captivity. However, the extent to which welfare benefits can be achieved through programmes developed primarily for cognitive research is unknown. We tested the impact of voluntary participation cognitive testing on the welfare of a socially housed group of crested macaques (Macaca nigra at the Macaque Study Centre (Marwell Zoo. First, we compared the rate of self-directed and social behaviours on testing and non-testing days, and between conditions within testing days. Minimal differences in behaviour were found when comparing testing and non-testing days, suggesting that there was no negative impact on welfare as a result of cognitive testing. Lipsmacking behaviours were found to increase and aggressive interaction was found to decrease in the group as a result of testing. Second, social network analysis was used to assess the effect of testing on associations and interactions between individuals. The social networks showed that testing subjects increased their association with others during testing days. One interpretation of this finding could be that providing socially housed primates with an opportunity for individuals to separate from the group for short periods could help mimic natural patterns of sub-group formation and reunion in captivity. The findings suggest, therefore, that the welfare of captive primates can be improved through the use of cognitive testing in zoo environments.

Stopping of hypervelocity clusters in solids

International Nuclear Information System (INIS)

Anders, Christian; Ziegenhain, Gerolf; Urbassek, Herbert M; Bringa, Eduardo M

2011-01-01

Using molecular-dynamics simulations, we study the processes underlying the stopping of energetic clusters upon impact in matter. We investigate self-bombardment of both a metallic (Cu) and a van-der-Waals bonded (frozen Ar) target. Clusters with sizes up to N = 10 4 atoms and with energies per atom of E/N = 0.1-1600 eV atom -1 were studied. We find that the stopping force exerted on a cluster follows an N 2/3 -dependence with cluster size N; thus large clusters experience less stopping than equi-velocity atoms. In the course of being stopped, the cluster is strongly deformed and attains a roughly pancake shape. Due to the cluster inertia, maximum deformation occurs later than the maximum stopping force. The time scale of projectile stopping is set by t 0 , the time the cluster needs to cover its own diameter before impacting the target; it thus depends on both cluster size and velocity. The time when the cluster experiences its maximum stopping force is around (0.7-0.8)t 0 . We find that the cluster is deformed with huge strain rates of around 1/2t 0 ; this amounts to 10 11 -10 13 s -1 for the cases studied here. (paper)

DebrisLV Hypervelocity Impact Post-Shot Physical Results Summary

Science.gov (United States)

2015-02-27

simulaFng  a  solar-­‐panel   •  15  MJoules  energy   •  6061-T6 Frame •  Nylon Body •  Hollow Center for Electronics BODY...model  results  to  predict   plasm  jet  formaOon  in  relaOvely  simple  structures.    More  modeling  needs  to...Post-­‐Shot  Materials  Physics  Results,”   TOR-­‐2014-­‐03192   Approved Electronically by: Technical Peer Review Performed by

High strain rate deformation of layered nanocomposites

Science.gov (United States)

Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

2012-11-01

Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

High strain rate deformation of layered nanocomposites.

Science.gov (United States)

Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A; Thomas, Edwin L

2012-01-01

Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

Generation of sub-gigabar-pressure shocks by a hyper-velocity impact in the collider driven by laser-induced cavity pressure

Science.gov (United States)

Badziak, J.; Kucharik, M.; Liska, R.

2018-02-01

The generation of high-pressure shocks in the newly proposed collider in which the projectile impacting a solid target is driven by the laser-induced cavity pressure acceleration (LICPA) mechanism is investigated using two-dimensional hydrodynamic simulations. The dependence of parameters of the shock generated in the target by the impact of a gold projectile on the impacted target material and the laser driver energy is examined. It is found that both in case of low-density (CH, Al) and high-density (Au, Cu) solid targets the shock pressures in the sub-Gbar range can be produced in the LICPA-driven collider with the laser energy of only a few hundreds of joules, and the laser-to-shock energy conversion efficiency can reach values of 10 - 20 %, by an order of magnitude higher than the conversion efficiencies achieved with other laser-based methods used so far.

Results of a diesel multiple unit fuel tank blunt impact test

Science.gov (United States)

2017-04-04

The Federal Railroad Administrations Office of Research and Development is conducting research into passenger locomotive fuel tank crashworthiness. A series of impact tests is being conducted to measure fuel tank deformation under two types of dyn...

A Comparative Analysis of the Magnetic Field Signals over Impact Structures on the Earth, Mars and the Moon

Science.gov (United States)

Isac, Anca; Mandea, Mioara; Purucker, Michael; Langlais, Benoit

2015-01-01

An improved description of magnetic fields of terrestrial bodies has been obtained from recent space missions, leading to a better characterization of the internal fields including those of crustal origin. One of the striking differences in their crustal magnetic field is the signature of large impact craters. A comparative analysis of the magnetic characteristics of these structures can shed light on the history of their respective planetary-scale magnetic dynamos. This has motivated us to identify impact craters and basins, first by their quasi-circular features from the most recent and detailed topographic maps and then from available global magnetic field maps. We have examined the magnetic field observed above 27 complex craters on the Earth, 34 impact basins on Mars and 37 impact basins on the Moon. For the first time, systematic trends in the amplitude and frequency of the magnetic patterns, inside and outside of these structures are observed for all three bodies. The demagnetization effects due to the impact shock wave and excavation processes have been evaluated applying the Equivalent Source Dipole forward modeling approach. The main characteristics of the selected impact craters are shown. The trends in their magnetic signatures are indicated, which are related to the presence or absence of a planetary-scale dynamo at the time of their formation and to impact processes. The low magnetic field intensity at center can be accepted as the prime characteristic of a hypervelocity impact and strongly associated with the mechanics of impact crater formation. In the presence of an active internal field, the process of demagnetization due to the shock impact is associated with post-impact remagnetization processes, generating a more complex magnetic signature.

Full scale test results for ship ice impact forces and pressures

International Nuclear Information System (INIS)

Ghoneim, G.A.

1993-01-01

A set of full scale impact tests were carried out for the icebreakers Canmar Kigoriak and Robert LeMeur in first and multi-year ice conditions in the southern Beaufort Sea. Preliminary results of the testing program were published in Ghoneim et al. (1984). This paper presents some salient results of further analysis of the data. This includes a description of the different types of ice ramming mechanisms and the corresponding ice force time histories and ship response. A comparison between the bow force peak values for the kigoriak and the Robert LeMeur is made and the reasons for the difference are evaluated. The question of dynamic magnification of the response is investigated. The relationship between the peak impact force and the ramming velocity is evaluated for both ships and compared with theoretical and empirical formulations. Other parametric relationships are presented, including such parameters as force duration and relative magnitude of the impact and beaching bow forces. The added mass is evaluated from measured accelerations and calculated bow forces and are shown to be time dependent. The relationship between ice pressure and corresponding contact area is discussed. Finally, conclusions and recommendations are presented

Quantitative impact characterization of aeronautical CFRP materials with non-destructive testing methods

Energy Technology Data Exchange (ETDEWEB)

Kiefel, Denis, E-mail: Denis.Kiefel@airbus.com, E-mail: Rainer.Stoessel@airbus.com; Stoessel, Rainer, E-mail: Denis.Kiefel@airbus.com, E-mail: Rainer.Stoessel@airbus.com [Airbus Group Innovations, Munich (Germany); Grosse, Christian, E-mail: Grosse@tum.de [Technical University Munich (Germany)

2015-03-31

In recent years, an increasing number of safety-relevant structures are designed and manufactured from carbon fiber reinforced polymers (CFRP) in order to reduce weight of airplanes by taking the advantage of their specific strength into account. Non-destructive testing (NDT) methods for quantitative defect analysis of damages are liquid- or air-coupled ultrasonic testing (UT), phased array ultrasonic techniques, and active thermography (IR). The advantage of these testing methods is the applicability on large areas. However, their quantitative information is often limited on impact localization and size. In addition to these techniques, Airbus Group Innovations operates a micro x-ray computed tomography (μ-XCT) system, which was developed for CFRP characterization. It is an open system which allows different kinds of acquisition, reconstruction, and data evaluation. One main advantage of this μ-XCT system is its high resolution with 3-dimensional analysis and visualization opportunities, which enables to gain important quantitative information for composite part design and stress analysis. Within this study, different NDT methods will be compared at CFRP samples with specified artificial impact damages. The results can be used to select the most suitable NDT-method for specific application cases. Furthermore, novel evaluation and visualization methods for impact analyzes are developed and will be presented.

Quantitative impact characterization of aeronautical CFRP materials with non-destructive testing methods

International Nuclear Information System (INIS)

Kiefel, Denis; Stoessel, Rainer; Grosse, Christian

2015-01-01

In recent years, an increasing number of safety-relevant structures are designed and manufactured from carbon fiber reinforced polymers (CFRP) in order to reduce weight of airplanes by taking the advantage of their specific strength into account. Non-destructive testing (NDT) methods for quantitative defect analysis of damages are liquid- or air-coupled ultrasonic testing (UT), phased array ultrasonic techniques, and active thermography (IR). The advantage of these testing methods is the applicability on large areas. However, their quantitative information is often limited on impact localization and size. In addition to these techniques, Airbus Group Innovations operates a micro x-ray computed tomography (μ-XCT) system, which was developed for CFRP characterization. It is an open system which allows different kinds of acquisition, reconstruction, and data evaluation. One main advantage of this μ-XCT system is its high resolution with 3-dimensional analysis and visualization opportunities, which enables to gain important quantitative information for composite part design and stress analysis. Within this study, different NDT methods will be compared at CFRP samples with specified artificial impact damages. The results can be used to select the most suitable NDT-method for specific application cases. Furthermore, novel evaluation and visualization methods for impact analyzes are developed and will be presented

Uniform Foam Crush Testing for Multi-Mission Earth Entry Vehicle Impact Attenuation

Science.gov (United States)

Patterson, Byron W.; Glaab, Louis J.

2012-01-01

Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes and retro-rockets, instead using built-in impact attenuators to absorb energy remaining at impact to meet landing loads requirements. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs and develop the trade space. Testing was conducted to characterize the material properties of several candidate impact foam attenuators to enhance M-SAPE analysis. In the current effort, four different Rohacell foams are tested at three different, uniform, strain rates (approximately 0.17, approximately 100, approximately 13,600%/s). The primary data analysis method uses a global data smoothing technique in the frequency domain to remove noise and system natural frequencies. The results from the data indicate that the filter and smoothing technique are successful in identifying the foam crush event and removing aberrations. The effect of strain rate increases with increasing foam density. The 71-WF-HT foam may support Mars Sample Return requirements. Several recommendations to improve the drop tower test technique are identified.

Influence of fall height on high impact polystyrene deformation and characteristics of drop weight test

Directory of Open Access Journals (Sweden)

Mizera Ales

2017-01-01

Full Text Available This study deals with high impact polystyrene (HIPS which was subjected the drop-weight test. HIPS is a polymer produced by the reaction between butadiene synthetic elastomer and styrene (5–14 % which contains the crystal polymer in certain amounts and is commonly used in mechanical engineering applications where machine parts are exposed to impact loading. The injection moulded HIPS samples were subjected the penetration test at different fall heights and the results were subsequently evaluated and discussed. It was found out that all fall heights are suitable for HIPS penetration, but the optimal one is 50 J because of the smallest variation range. Higher heights are not needed because of increasing power consumption of the test device. From the results, it is clear, that HIPS is not so highly impact resistant material as for example HDPE, because of that is this material suitable for applications where is not often exposed to too big impacts at high velocities.

Lightweight Ablative and Ceramic Thermal Protection System Materials for NASA Exploration Systems Vehicles

Science.gov (United States)

Valentine, Peter G.; Lawrence, Timothy W.; Gubert, Michael K.; Milos, Frank S.; Kiser, James D.; Ohlhorst, Craig W.; Koenig, John R.

2006-01-01

As a collaborative effort among NASA Centers, the "Lightweight Nonmetallic Thermal Protection Materials Technology" Project was set up to assist mission/vehicle design trade studies, to support risk reduction in thermal protection system (TPS) material selections, to facilitate vehicle mass optimization, and to aid development of human-rated TPS qualification and certification plans. Missions performing aerocapture, aerobraking, or direct aeroentry rely on advanced heatshields that allow reductions in spacecraft mass by minimizing propellant requirements. Information will be presented on candidate materials for such reentry approaches and on screening tests conducted (material property and space environmental effects tests) to evaluate viable candidates. Seventeen materials, in three classes (ablatives, tiles, and ceramic matrix composites), were studied. In additional to physical, mechanical, and thermal property tests, high heat flux laser tests and simulated-reentry oxidation tests were performed. Space environmental effects testing, which included exposures to electrons, atomic oxygen, and hypervelocity impacts, was also conducted.

A framework for testing the ability of models to project climate change and its impacts

DEFF Research Database (Denmark)

Refsgaard, J. C.; Madsen, H.; Andréassian, V.

2014-01-01

Models used for climate change impact projections are typically not tested for simulation beyond current climate conditions. Since we have no data truly reflecting future conditions, a key challenge in this respect is to rigorously test models using proxies of future conditions. This paper presents...... a validation framework and guiding principles applicable across earth science disciplines for testing the capability of models to project future climate change and its impacts. Model test schemes comprising split-sample tests, differential split-sample tests and proxy site tests are discussed in relation...... to their application for projections by use of single models, ensemble modelling and space-time-substitution and in relation to use of different data from historical time series, paleo data and controlled experiments. We recommend that differential-split sample tests should be performed with best available proxy data...

SIMS chemical analysis of extended impacts on the leading and trailing edges of LDEF experiment AO187-2

Science.gov (United States)

Amari, S.; Foote, J.; Swan, P.; Walker, R. M.; Zinner, E.; Lange, G.

1993-01-01

Numerous 'extended impacts' found in both leading and trailing edge capture cells were successfully analyzed for the chemical composition of projectile residues by secondary ion mass spectrometry (SIMS). Most data were obtained from the trailing edge cells where 45 of 58 impacts were classified as 'probably natural' and the remainder as 'possibly man-made debris.' This is in striking contrast to leading edge cells where 9 of 11 impacts so far measured are definitely classified as orbital debris. Although all the leading edge cells had lost their plastic entrance foils during flight, the rate of foil failure was similar to that of the trailing edge cells, 10 percent of which were recovered intact. Ultraviolet embrittlement is suspected as the major cause of failure on both leading and trailing edges. The major impediment to the accurate determination of projectile chemistry is the fractionation of volatile and refractory elements in the hypervelocity impact and redeposition processes. This effect had been noted in a simulation experiment but is more pronounced in the LDEF capture cells, probably due to the higher average velocities of the space impacts. Surface contamination of the pure Ge surfaces with a substance rich in Si, but also containing Mg and Al, provides an additional problem for the accurate determination of impactor chemistry. The effect is variable, being much larger on surfaces that were exposed to space than in those cells that remained intact. Future work will concentrate on the analyses of more leading edge impacts and the development of new SIMS techniques for the measurement of elemental abundances in extended impacts.

Prediction of fracture toughness K/sub Ic/ of steel from Charpy impact test results

Energy Technology Data Exchange (ETDEWEB)

Iwadate, Tadao; Tanaka, Yasuhiko; Takemata, Hiroyuki; Terashima, Shuhei

1986-08-01

This paper presents a method to predict the fracture toughness K/sub Ic/ and/or K/sub Id/ of steels using their Charpy impact test results and tensile properties. The fracture toughness, Charpy impact and tensile properties of 2 1/4 Cr-1Mo, ASTM A508 Cl.1, A508 Cl.2 A508 Cl.3 and A533 Gr.B Cl.1 steels were measured and analysed on the basis of the excess temperature (test temperature minus FATT) and Rolfe-Novak correlation. The relationship between K/sub Ic//K/sub Ic-us/ and the excess temperature, where K/sub Ic-us/ is the upper-shelf fracture toughness K/sub Ic/ predicted by Rolfe-Novak correlation, discloses that the K/sub Ic/ transition curves of several steels are representable by only one trend curve of K/sub Ic//K/sub Ic-us/ or K/sub Id//K/sub Id-us/ versus excess temperature relation. This curve is denoted as a ''master curve''. By using this curve, the fracture toughness of steel can be predicted using Charpy impact and tensile test results. By taking account of the scattering of both the fracture toughness and Charpy impact test results, the confidence limits of the master curve were also determined. Another approach to develop more general procedure of predicting the fracture toughness K/sub Ic/ is also discussed.

Impact of changed legislation on skin tests: the present and future

NARCIS (Netherlands)

Klimek, Ludger; Hoffmann, Hans Jürgen; Kugler, Alexa; Muraro, Antonella; Hellings, Peter W.

2016-01-01

To discuss the impact of current European Union regulations on the availability of commercially available skin test allergens in European member states. European Union legislations now define diagnostic allergens to be medicine requiring market authorization of every individual diagnostic allergen

Elemental Water Impact Test: Phase 3 Plunge Depth of a 36-Inch Aluminum Tank Head

Science.gov (United States)

Vassilakos, Gregory J.

2014-01-01

Spacecraft are being designed based on LS-DYNA water landing simulations. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. Phase 3 featured a composite tank head that was tested at a range of heights to verify the ability to predict structural failure of composites. To support planning for Phase 3, a test series was conducted with an aluminum tank head dropped from heights of 2, 6, 10, and 12 feet to verify that the test article would not impact the bottom of the test pool. This report focuses on the comparisons of the measured plunge depths to LS-DYNA predictions. The results for the tank head model demonstrated the following. 1. LS-DYNA provides accurate predictions for peak accelerations. 2. LS-DYNA consistently under-predicts plunge depth. An allowance of at least 20% should be added to the LS-DYNA predictions. 3. The LS-DYNA predictions for plunge depth are relatively insensitive to the fluid-structure coupling stiffness.

Application of computer techniques to charpy impact testing of irradiated pressure vessel steels

International Nuclear Information System (INIS)

Landow, M.P.; Fromm, E.O.; Perrin, J.S.

1982-01-01

A Rockwell AIM 65 microcomputer has been modified to control a remote Charpy V-notch impact test machine. It controls not only handling and testing of the specimen but also transference and storage of instrumented Charpy test data. A system of electrical solenoid activated pneumatic cylinders and switches provides the interface between the computer and the test apparatus. A command language has been designated that allows the operator to command checkout, test procedure, and data storage via the computer. Automatic compliance with ASTM test procedures is built into the program

Instrumented Impact Testing: Influence of Machine Variables and Specimen Position

International Nuclear Information System (INIS)

Lucon, E.; McCowan, C. N.; Santoyo, R. A.

2008-01-01

An investigation has been conducted on the influence of impact machine variables and specimen positioning on characteristic forces and absorbed energies from instrumented Charpy tests. Brittle and ductile fracture behavior has been investigated by testing NIST reference samples of low, high and super-high energy levels. Test machine variables included tightness of foundation, anvil and striker bolts, and the position of the center of percussion with respect to the center of strike. For specimen positioning, we tested samples which had been moved away or sideways with respect to the anvils. In order to assess the influence of the various factors, we compared mean values in the reference (unaltered) and altered conditions; for machine variables, t-test analyses were also performed in order to evaluate the statistical significance of the observed differences. Our results indicate that the only circumstance which resulted in variations larger than 5 percent for both brittle and ductile specimens is when the sample is not in contact with the anvils. These findings should be taken into account in future revisions of instrumented Charpy test standards.

Instrumented Impact Testing: Influence of Machine Variables and Specimen Position

Energy Technology Data Exchange (ETDEWEB)

Lucon, E.; McCowan, C. N.; Santoyo, R. A.

2008-09-15

An investigation has been conducted on the influence of impact machine variables and specimen positioning on characteristic forces and absorbed energies from instrumented Charpy tests. Brittle and ductile fracture behavior has been investigated by testing NIST reference samples of low, high and super-high energy levels. Test machine variables included tightness of foundation, anvil and striker bolts, and the position of the center of percussion with respect to the center of strike. For specimen positioning, we tested samples which had been moved away or sideways with respect to the anvils. In order to assess the influence of the various factors, we compared mean values in the reference (unaltered) and altered conditions; for machine variables, t-test analyses were also performed in order to evaluate the statistical significance of the observed differences. Our results indicate that the only circumstance which resulted in variations larger than 5 percent for both brittle and ductile specimens is when the sample is not in contact with the anvils. These findings should be taken into account in future revisions of instrumented Charpy test standards.

Mega-impacts and mantle-melting episodes: tests of possible correlations

International Nuclear Information System (INIS)

Glikson, A.Y.

1996-01-01

The criteria for recognising the effects of impacts by large-diameter extraterrestrial projectiles (D p >>10 km) on thin, geothermally active crust must vary fundamentally from those pertaining to impacts on thick, cooler continental crust. Although the bulk of the terrestrial cratering records has been destroyed by both erosion of elevated terrains and plate subduction, or obscured by burial, a search for Precambrian mega-impacts is facilitated by the preservation of their likely secondary effects: mega-earthquake-triggered faults; ensuing diamictites, and the deposits of turbidity currents; microtektites; spherulitic condensates of vaporised asteroid and target materials; and distal tectonic and igeneous effects. Clues to the origin of thermal events are provided by peaks on isotopic-age histograms of precise U-Pb, Ar-Ar, amd Sm-Nd mineral-whole-rock ages. These peaks, spatially corroborated by detailed mapping of Precambrian terrains, support an episodic nature of at least certain major Precambrian events and some correlations with impact events. Preliminary time-series analyses of Precambrian events yield values consistent with the Phanerozoic galactic rotation period (250 ± 50 Ma), and the solar system's cross-galactic-plane oscillation period (33 ± 3 Ma). It has been demonstrated that possible correlations between mega-impacts and tectonic/thermal events are capable of being tested through isotopic-age studies of diamictites and spherule units of impact origin and of rifting and mafic igneous events. 123 refs., 2 tabs., 7 figs

Modeling and simulation of Charpy impact test of maraging steel 300 using Abaqus

Science.gov (United States)

Madhusudhan, D.; Chand, Suresh; Ganesh, S.; Saibhargavi, U.

2018-03-01

This work emphasizes the modeling and simulation of Charpy impact test to evaluate fracture energy at different pendulum velocities of armor maraging steel 300 using ABAQUS. To evaluate the fracture energy, V-notch specimen is fractured using the Johnson and Cook Damage model. The Charpy impact tests are of great importance related to fracture properties of steels. The objective of this work is to present absorbed energy variation at pendulum velocities of 5 m/sec, 6 m/sec, 7 m/sec and 9 m/sec in addition to stress distribution at v-notch. Finite Element Method of modeling for three dimensional specimens is used for simulation in commercial software of ABAQUS.

The DT-19 container design, impact testing and analysis

International Nuclear Information System (INIS)

Aramayo, G.A.; Goins, M.L.

1995-01-01

Containers used by the Department of Energy (DOE) for the transport of radioactive material components, including components and special assemblies, are required to meet certain impact and thermal requirements that are demonstrated by performance or compliance testing, analytical procedures or a combination of both. The Code of Federal Regulations (CFR) Part 49, Section 173.7(d) stipulates that, 'Packages (containers) made by or under direction of the US DOE may be used for the transportation of radioactive materials when evaluated, approved, and certified by the DOE against packaging standards equivalent to those specified in 10 CFR Part 71. This paper describes the details of the design, analysis and testing efforts undertaken to improve the overall structural and thermal integrity of the DC-19 shipping container

On the validity of Ksub(Id)-measurements in instrumented impact tests

International Nuclear Information System (INIS)

Kalthoff, J.F.; Winkler, S.; Klemm, W.; Beinert, J.

1979-01-01

The influence of inertia effects in determining the dynamic fracture toughness Ksub(Id) by instrumented impact testing is investigated. Model experiments in the brittle fracture regime are carried out with precracked bend specimens machined from the epoxy resin Araldite B. As is usual in these tests, the loads at the tup of the impinging striker are recorded as a function of time during the impact process. For reference purposes, the dynamic fracture toughness value Ksub(Id)sup(m1) is derived from the measured maximum load utilizing static stress intensity factor formulas. In addition to this conventional procedure, the actual stress intensity factors are measured directly at the tip of the crack by means of the shadow optical method of caustics applied in combination with high speed photography. The critical value of these optically measured stress intensity factors (for onset of crack propagation), Ksub(Id)sup(opt), is the true dynamic fracture toughness. In the experiments, the specimen size and the impact velocity were varied. In accordance with expectations, it is found that the hammer load signal is not correlated with the actual crack tip stress intensity factor values by a simple proportionality. The conventionally determined Ksub(Id)sup(m1)-value overestimates the true dynamic fracture toughness Ksub(Id)sup(opt). This overestimation becomes larger for larger specimen sizes and larger impact velocities. The results demonstrate the dominating influence inertia effects can have on hammer load measurements and emphasize the importance of eliminating these effects in order to determine non-erroneous dynamic fracture toughness values. (orig.)

Nano-impact testing of TiFeN and TiFeMoN films for dynamic toughness evaluation

Energy Technology Data Exchange (ETDEWEB)

Beake, B D [Micro Materials Ltd, Willow House, Ellice Way, Yale Business Village, Wrexham LL13 7YL (United Kingdom); Vishnyakov, V M; Colligon, J S, E-mail: ben@micromaterials.co.uk [Dalton Research Institute, Manchester Metropolitan University, Manchester M1 5GD (United Kingdom)

2011-03-02

TiFeN and TiFeMoN films were deposited on silicon wafers by ion-beam-assisted deposition. Their mechanical properties were measured by nanoindentation (quasi-static) and nano-impact (dynamic) techniques. Nano-impact testing enabled assessment of their toughness and resistance to fatigue fracture under repetitive loading. At low impact forces, films with a higher resistance to plastic deformation (H{sup 3}/E{sup 2}) were much more resistant to the formation of cracks throughout the test. At higher impact forces, these films initially show impact resistance but with continued impacts they are unable to protect the Si substrate, performing as poorly as films with lower H{sup 3}/E{sup 2} and suffer delamination from the Si substrate over a large area.

Low amplitude impact of PBX 9501: Modified Steven spigot gun tests

Energy Technology Data Exchange (ETDEWEB)

Idar, D.J.; Lucht, R.A.; Straight, J.W. [and others

1998-12-01

Low-velocity mechanical impact and subsequent high explosive (HE) reaction are of concern in credible accident scenarios involving the handling, transport, and storage of nuclear weapons. Using modified Steven spigot gun tests, the authors have investigated the high-explosive violent-reaction (HEVR) potential of PBX 9501 to low-amplitude insult. Reliable modeling predictions require that one identify the relevant parameters and behavioral responses that are key to the reaction mechanism(s) in PBX 9501. Additional efforts have been targeted at identifying relevant differences in the response between baseline and stockpile-aged PBX 9501 to low-velocity impacts.

A Blind Test of the Younger Dryas Impact Hypothesis.

Directory of Open Access Journals (Sweden)

Vance Holliday

Full Text Available The Younger Dryas Impact Hypothesis (YDIH states that North America was devastated by some sort of extraterrestrial event ~12,800 calendar years before present. Two fundamental questions persist in the debate over the YDIH: Can the results of analyses for purported impact indicators be reproduced? And are the indicators unique to the lower YD boundary (YDB, i.e., ~12.8k cal yrs BP? A test reported here presents the results of analyses that address these questions. Two different labs analyzed identical splits of samples collected at, above, and below the ~12.8ka zone at the Lubbock Lake archaeological site (LL in northwest Texas. Both labs reported similar variation in levels of magnetic micrograins (>300 mg/kg >12.8ka and <11.5ka, but <150 mg/kg 12.8ka to 11.5ka. Analysis for magnetic microspheres in one split, reported elsewhere, produced very low to nonexistent levels throughout the section. In the other split, reported here, the levels of magnetic microspherules and nanodiamonds are low or nonexistent at, below, and above the YDB with the notable exception of a sample <11,500 cal years old. In that sample the claimed impact proxies were recovered at abundances two to four orders of magnitude above that from the other samples. Reproducibility of at least some analyses are problematic. In particular, no standard criteria exist for identification of magnetic spheres. Moreover, the purported impact proxies are not unique to the YDB.

A simulation test of the impact on soil moisture by agricultural ...

African Journals Online (AJOL)

To study the impact by agricultural machinery on changes in soil moisture, we used a simulated test method employing round iron plate based on the ground pressure ratio between the front and rear wheels of wheeled tractors and crawler tractors. We conducted soil compactions with five pressure loads (35, 98, 118, 196 ...

Advanced SEM/EDS Analysis using Stage Control and an annular Silicon Drift Detector: Applications in Impact Studies from Centimetre below Micrometre Scale

Science.gov (United States)

Salge, Tobias; Berlin, Jana; Terborg, Ralf; Howard, Kieren; Newsom, Horton; Wozniakiewicz, Penny; Price, Mark; Burchell, Mark; Cole, Mike; Kearsley, Anton

2013-04-01

Introduction: Imaging of ever smaller structures, in situ within large samples, requires low electron beam energy (HV300°C) hydrothermal event [2]. (C) In experimental hypervelocity impact craters, spectrum images readily find locations of projectile residue throughout all the complex topography. The very high count rate at even low beam energy and current reveals inhomogeneous compositions and textures below micrometre scale [3]. These results help us understand preservation and modification of structure and composition in the fine-grained cometary dust aggregates which made aluminium foil craters on the Stardust spacecraft during its encounter with comet Wild 2. Acknowledgements: International Continental Scientific Drilling Program and the Museum of Natural History Berlin for providing samples. References: [1] K.T. Howard 2011. Geological Society of London: 573-591. [2] M. Nelson et al. 2012. GCA 86: 1-20. [3] A. T. Kearsley et al. 2013. Submitted to LPSC #1910.

Dynamic Impact Analyses and Tests of Concrete Overpacks - 13638

Energy Technology Data Exchange (ETDEWEB)

Lee, Sanghoon; Cho, Sang-Soon; Kim, Ki-Young; Jeon, Je-Eon; Seo, Ki-Seog [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-07-01

Concrete cask is an option for spent nuclear fuel interim storage which is prevailingly used in US. A concrete cask usually consists of metallic canister which confines the spent nuclear fuel and concrete overpack. When the overpack undergoes a severe missile impact which might be caused by a tornado or an aircraft crash, it should sustain acceptable level of structural integrity so that its radiation shielding capability and the retrievability of canister are maintained. Missile impact against a concrete overpack involves two damage modes, local damage and global damage. Local damage of concrete is usually evaluated by empirical formulas while the global damage is evaluated by finite element analysis. In many cases, those two damage modes are evaluated separately. In this research, a series of numerical simulations are performed using finite element analysis to evaluate the global damage of concrete overpack as well as its local damage under high speed missile impact. We consider two types of concrete overpack, one with steel in-cased concrete without reinforcement and the other with partially-confined reinforced concrete. The numerical simulation results are compared with test results and it is shown that appropriate modeling of material failure is crucial in this analysis and the results are highly dependent on the choice of failure parameters. (authors)

Dynamic Impact Analyses and Tests of Concrete Overpacks - 13638

International Nuclear Information System (INIS)

Lee, Sanghoon; Cho, Sang-Soon; Kim, Ki-Young; Jeon, Je-Eon; Seo, Ki-Seog

2013-01-01

Concrete cask is an option for spent nuclear fuel interim storage which is prevailingly used in US. A concrete cask usually consists of metallic canister which confines the spent nuclear fuel and concrete overpack. When the overpack undergoes a severe missile impact which might be caused by a tornado or an aircraft crash, it should sustain acceptable level of structural integrity so that its radiation shielding capability and the retrievability of canister are maintained. Missile impact against a concrete overpack involves two damage modes, local damage and global damage. Local damage of concrete is usually evaluated by empirical formulas while the global damage is evaluated by finite element analysis. In many cases, those two damage modes are evaluated separately. In this research, a series of numerical simulations are performed using finite element analysis to evaluate the global damage of concrete overpack as well as its local damage under high speed missile impact. We consider two types of concrete overpack, one with steel in-cased concrete without reinforcement and the other with partially-confined reinforced concrete. The numerical simulation results are compared with test results and it is shown that appropriate modeling of material failure is crucial in this analysis and the results are highly dependent on the choice of failure parameters. (authors)

Compressed gas combined single- and two-stage light-gas gun

Science.gov (United States)

Lamberson, L. E.; Boettcher, P. A.

2018-02-01

With more than 1 trillion artificial objects smaller than 1 μm in low and geostationary Earth orbit, space assets are subject to the constant threat of space debris impact. These collisions occur at hypervelocity or speeds greater than 3 km/s. In order to characterize material behavior under this extreme event as well as study next-generation materials for space exploration, this paper presents a unique two-stage light-gas gun capable of replicating hypervelocity impacts. While a limited number of these types of facilities exist, they typically are extremely large and can be costly and dangerous to operate. The design presented in this paper is novel in two distinct ways. First, it does not use a form of combustion in the first stage. The projectile is accelerated from a pressure differential using air and inert gases (or purely inert gases), firing a projectile in a nominal range of 1-4 km/s. Second, the design is modular in that the first stage sits on a track sled and can be pulled back and used in itself to study lower speed impacts without any further modifications, with the first stage piston as the impactor. The modularity of the instrument allows the ability to investigate three orders of magnitude of impact velocities or between 101 and 103 m/s in a single, relatively small, cost effective instrument.

40th Annual Armament Systems: Guns-Ammunition-Rockets-Missiles Conference and Exhibition

Science.gov (United States)

2005-04-28

PM] Abraham Overview, Mr. Robert Daunfeldt, Bofors Defence Summary Overview of an Advanced 2.75 Hypervelocity Weapon, Mr. Larry Bradford , CAT Flight...Substantially Improves 2.75 Rocket Lethality, Safety, Survivability Mr. Larry Bradford , CAT Flight Services, Inc. APKWS Flight Test Results Mr. Larry S

2005 40th Annual Armament Systems Guns - Ammunition - Rockets - Missiles Conference and Exhibition. Volume 1: Tuesday

Science.gov (United States)

2005-04-28

PM] Abraham Overview, Mr. Robert Daunfeldt, Bofors Defence Summary Overview of an Advanced 2.75 Hypervelocity Weapon, Mr. Larry Bradford , CAT Flight...Substantially Improves 2.75 Rocket Lethality, Safety, Survivability Mr. Larry Bradford , CAT Flight Services, Inc. APKWS Flight Test Results Mr. Larry S

2005 40th Annual Armament Systems: Guns - Ammunition - Rockets - Missiles Conference and Exhibition. Volume 3: Wednesday

Science.gov (United States)

2005-04-28

PM] Abraham Overview, Mr. Robert Daunfeldt, Bofors Defence Summary Overview of an Advanced 2.75 Hypervelocity Weapon, Mr. Larry Bradford , CAT Flight...Substantially Improves 2.75 Rocket Lethality, Safety, Survivability Mr. Larry Bradford , CAT Flight Services, Inc. APKWS Flight Test Results Mr. Larry S

Estimation of integrity of cast-iron cask against impact due to free drop test, (1)

International Nuclear Information System (INIS)

Itoh, Chihiro

1988-01-01

Ductile cast iron is examined to use for shipping and storage cask from a economic point of view. However, ductile cast iron is considered to be a brittle material in general. Therefore, it is very important to estimate the integrity of cast iron cask against brittle failure due to impact load at 9 m drop test and 1 m derop test on to pin. So, the F.E.M. analysis which takes nonlinearity of materials into account and the estimation against brittle failure by the method which is proposed in this report were carried out. From the analysis, it is made clear that critical flaw depth (the minimum depth to initiate the brittle failure) is 21.1 mm and 13.1 mm in the case of 9 m drop test and 1 m drop test on to pin respectively. These flaw depth can be detected by ultrasonic test. Then, the cask is assured against brittle failure due to impact load at 9 m drop test and 1 m drop test on to pin. (author)

Topics in the Analysis of Shear-Wave Propagation in Oblique-Plate Impact Tests

National Research Council Canada - National Science Library

Scheidler, Mike

2007-01-01

This report addresses several topics in the theoretical analysis of shock waves, acceleration waves, and centered simple waves, with emphasis on the propagation of shear waves generated in oblique-plate impact tests...

The impact of usability reports and user test observations on developers understanding of usability data

DEFF Research Database (Denmark)

Høegh, Rune Thaarup; Nielsen, Christian Monrad; Pedersen, Michael Bach

2006-01-01

of the system. This article presents results from an exploratory study of 2 ways of providing feedback from a usability evaluation: observation of user tests and reading usability reports. A case study and a field experiment were used to explore how observation and usability reports impact developers......' understanding of usability data. The results indicate that observation of user tests facilitated a rich understanding of usability problems and created empathy with the users and their work. The usability report had a strong impact on the developers' understanding of specific usability problems and supported...

Assessing the Impact of Testing Aids on Post-Secondary Student Performance: A Meta-Analytic Investigation

Science.gov (United States)

Larwin, Karen H.; Gorman, Jennifer; Larwin, David A.

2013-01-01

Testing aids, including student-prepared testing aids (a.k.a., cheat sheets or crib notes) and open-textbook exams, are common practice in post-secondary assessment. There is a considerable amount of published research that discusses and investigates the impact of these testing aids. However, the findings of this research are contradictory and…

Including test errors in evaluating surveillance test intervals

International Nuclear Information System (INIS)

Kim, I.S.; Samanta, P.K.; Martorell, S.; Vesely, W.E.

1991-01-01

Technical Specifications require surveillance testing to assure that the standby systems important to safety will start and perform their intended functions in the event of plant abnormality. However, as evidenced by operating experience, the surveillance tests may be adversely impact safety because of their undesirable side effects, such as initiation of plant transients during testing or wearing-out of safety systems due to testing. This paper first defines the concerns, i.e., the potential adverse effects of surveillance testing, from a risk perspective. Then, we present a methodology to evaluate the risk impact of those adverse effects, focusing on two important kinds of adverse impacts of surveillance testing: (1) risk impact of test-caused trips and (2) risk impact of test-caused equipment wear. The quantitative risk methodology is demonstrated with several surveillance tests conducted at boiling water reactors, such as the tests of the main steam isolation valves, the turbine overspeed protection system, and the emergency diesel generators. We present the results of the risk-effectiveness evaluation of surveillance test intervals, which compares the adverse risk impact with the beneficial risk impact of testing from potential failure detection, along with insights from sensitivity studies

LX-04 VIOLENCE MEASUREMENTS- STEVEN TESTS IMPACTED BY PROJECTILES SHOT FROM A HOWITZER GUN

International Nuclear Information System (INIS)

Chidester, S K; Vandersall, K S; Switzer, L L; Tarver, C M

2005-01-01

Characterization of the reaction violence of LX-04 explosive (85% HMX and 15% Viton A by weight) was obtained from Steven Impact Tests performed above the reaction initiation threshold. A 155 mm Howitzer propellant driven gas gun was used to accelerate the Steven Test projectiles in the range of approximately 170-300 m/s to react (ignite) the LX-04 explosive. Blast overpressure gauges, acoustic microphones, and high-speed photography characterized the level of high explosive reaction violence. A detonation in this velocity range was not observed and when comparing these results (and the Susan test results) with that of other HMX based explosives, LX-04 has a more gradual reaction violence slope as the impact velocity increases. The high binder content (15%) of the LX-04 explosive is believed to be the key factor to the lower level of violence

Integrated assessment of pedestrian head impact protection in testing secondary safety and autonomous emergency braking.

Science.gov (United States)

Searson, D J; Anderson, R W G; Hutchinson, T P

2014-02-01

Pedestrian impact testing is used to provide information to the public about the relative level of protection provided by different vehicles to a struck pedestrian. Autonomous Emergency Braking (AEB) is a relatively new technology that aims to reduce the impact speed of such crashes. It is expected that vehicles with AEB will pose less harm to pedestrians, and that the benefit will come about through reductions in the number of collisions and a change in the severity of impacts that will still occur. In this paper, an integration of the assessment of AEB performance and impact performance is proposed based on average injury risk. Average injury risk is calculated using the result of an impact test and a previously published distribution of real world crash speeds. A second published speed distribution is used that accounts for the effects of AEB, and reduced average risks are implied. This principle allows the effects of AEB systems and secondary safety performance to be integrated into a single measure of safety. The results are used to examine the effect of AEB on Euro NCAP and ANCAP assessments using previously published results on the likely effect of AEB. The results show that, given certain assumptions about AEB performance, the addition of AEB is approximately the equivalent of increasing Euro NCAP test performance by one band, which corresponds to an increase in the score of 25% of the maximum. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fast-ignition heavy-ion fusion target by jet impact

International Nuclear Information System (INIS)

Velarde, P.; Ogando, F.; Eliezer, S.; Martinez-Val, J.M.

2005-01-01

A new target design for HIF, based on the fast-ignition principles, is proposed. Unlike the previous designs proposed so far, in this case just one energy source is needed to drive the whole process to ignition. The ultra-fast deposition of energy onto the compressed core is produced in this case by hypervelocity jets generated during the process. The collision of jets converts their kinetic energy into thermal energy of the nuclear fuel, which is expected to produce ignition under proper design. The process is studied in this paper, describing its most relevant features like jet production and later collision

Structural evaluation of spent nuclear fuel storage facilities under aircraft crash impact (2). Horizontal impact test onto reduced scale metal cask due to aircraft engine missile

International Nuclear Information System (INIS)

Namba, Kosuke; Shirai, Koji; Saegusa, Toshiari

2009-01-01

In this study, to confirm the sealing performance of a metal cask subjected to impact force due to possible commercial aircraft crash against a spent fuel storage facility, the horizontal impact test was carried out. In the test, an aircraft engine missile with a speed of 57.3 m/s attacked the reduced scale metal cask containing helium gas, which stands vertically. Then the leak rate and sliding displacement of the lid were measured. The leak rate increased rapidly and reached to 4.0 x 10 -6 Pa·m 3 /sec. After that, the leak rate decreased slowly and converged to 1.0x10 -6 Pa·m 3 /sec after 20 hours from the impact test. The leak rate of a full scale cask was evaluated using that of reduced scale cask obtained by the test. Then the leak rate of the full scale cask was 3.5x10 -5 Pa·m 3 /sec. This result showed that the sealing performance of the full scale metal cask would not be affected immediately by the horizontal impact of the aircraft engine with a speed of 57.3 m/s. (author)

Instrumented impact testing as a way to obtain further information on the behaviour of steel in welded constructions

International Nuclear Information System (INIS)

Nielsen, A.

1976-05-01

Based on experience gained from instrumented impact testing of ten different mild steels using test pieces of different geometrical shape (Charpy V-notch, Charpy knife-notch, DVM, Schnadt K 0 , Ksub(0.5), K 1 and K 2 ), some general features of the fracture process during impact testing are discussed. Steels can be divided into two main groups that are significantly different with respect to the behaviour during Charpy V-notch testing. The difference vanishes when a crack-like notch is used, and other properties of steel are revealed. It is evident that, even when modified impact testing bears little resemblance to what is happening in an actual steel construction. For the purpose of investigating the fracture conditions in welds, it seems more significant to relate the dynamic aspects to the speed of propagation of the crack when it starts to penetrate the volume considered at a certain stress level. (author)

How Well Does the Latest Anthropomorphic Test Device Mimic Human Impact Responses?

Science.gov (United States)

Newby, Nate; Somers, Jeff; Caldewll, Erin; Gernhardt, Michael

2014-01-01

One of the goals of the NASA Occupant Protection Group is to understand the human tolerance to dynamic loading. This knowledge has to come through indirect approaches such as existing human response databases, anthropometric test devices (ATD), animal testing, post-­-mortem human subjects, and models. This study investigated the biofidelity of the National Highway Traffic Safety Administration's ATD named the THOR (test device for human occupant restraint). If THOR responds comparably to humans, then it could potentially be used as a human surrogate to help validate space vehicle requirements for occupant protection. The THOR responses to frontal and spinal impacts (ranging from 8 to 12 G with rise times of 40, 70, and 100 ms) were measured and compared to human volunteer responses (95 trials in frontal and 58 in spinal) previously collected by the U. S. Air Force on the same horizontal impact accelerator. The impact acceleration profiles tested are within the expected range of multi-­-purpose crew vehicle (MPCV) landing dynamics. A correlation score was calculated for each THOR to human comparison using CORA (CORrelation and Analysis) software. A two-­-parameter beta distribution model fit was obtained for each dependent variable using maximum likelihood estimation. For frontal impacts, the THOR head x-­-acceleration peak response correlated with the human response at 8 and 10-­-G 100 ms but not 10-­-G 70 ms. The phase lagged the human response. Head z-­-acceleration was not correlated. Chest x-­-acceleration was in phase, had a higher peak response, and was well correlated with lighter subjects (Cora = 0.8 for 46 kg vs. Cora = 0.4 for 126 kg). Head x-­-displacement had a leading phase. Several subjects responded with the same peak displacement but the mean of the group was lower. The shoulder x-­-displacement was in phase but had higher peaks than the human response. For spinal impacts, the THOR head x-­-acceleration was not well correlated. Head and

Fluid-structure interaction analysis of the drop impact test for helicopter fuel tank.

Science.gov (United States)

Yang, Xianfeng; Zhang, Zhiqiang; Yang, Jialing; Sun, Yuxin

2016-01-01

The crashworthiness of helicopter fuel tank is vital to the survivability of the passengers and structures. In order to understand and improve the crashworthiness of the soft fuel tank of helicopter during the crash, this paper investigated the dynamic behavior of the nylon woven fabric composite fuel tank striking on the ground. A fluid-structure interaction finite element model of the fuel tank based on the arbitrary Lagrangian-Eulerian method was constructed to elucidate the dynamic failure behavior. The drop impact tests were conducted to validate the accuracy of the numerical simulation. Good agreement was achieved between the experimental and numerical results of the impact force with the ground. The influences of the impact velocity, the impact angle, the thickness of the fuel tank wall and the volume fraction of water on the dynamic responses of the dropped fuel tank were studied. The results indicated that the corner of the fuel tank is the most vulnerable location during the impact with ground.

Impact of Laboratory Test Use Strategies in a Turkish Hospital.

Directory of Open Access Journals (Sweden)

Fatma Meriç Yılmaz

Full Text Available Eliminating unnecessary laboratory tests is a good way to reduce costs while maintain patient safety. The aim of this study was to define and process strategies to rationalize laboratory use in Ankara Numune Training and Research Hospital (ANH and calculate potential savings in costs.A collaborative plan was defined by hospital managers; joint meetings with ANHTA and laboratory professors were set; the joint committee invited relevant staff for input, and a laboratory efficiency committee was created. Literature was reviewed systematically to identify strategies used to improve laboratory efficiency. Strategies that would be applicable in local settings were identified for implementation, processed, and the impact on clinical use and costs assessed for 12 months.Laboratory use in ANH differed enormously among clinics. Major use was identified in internal medicine. The mean number of tests per patient was 15.8. Unnecessary testing for chloride, folic acid, free prostate specific antigen, hepatitis and HIV testing were observed. Test panel use was pinpointed as the main cause of overuse of the laboratory and the Hospital Information System test ordering page was reorganized. A significant decrease (between 12.6-85.0% was observed for the tests that were taken to an alternative page on the computer screen. The one year study saving was equivalent to 371,183 US dollars.Hospital-based committees including laboratory professionals and clinicians can define hospital based problems and led to a standardized approach to test use that can help clinicians reduce laboratory costs through appropriate use of laboratory tests.

2005 40th Annual Armament Systems: Guns - Ammunition - Rockets - Missiles Conference and Exhibition. Volume 2: Wednesday

Science.gov (United States)

2005-04-28

PM] Abraham Overview, Mr. Robert Daunfeldt, Bofors Defence Summary Overview of an Advanced 2.75 Hypervelocity Weapon, Mr. Larry Bradford , CAT Flight...Substantially Improves 2.75 Rocket Lethality, Safety, Survivability Mr. Larry Bradford , CAT Flight Services, Inc. APKWS Flight Test Results Mr. Larry S...Company Lead: Larry Bradford Atlantic Research Propellant Mixing/Loading, Nozzle Manufacturing, Corporation Motor Static Testing Company Lead: Steve

Testing the impact on natural risks' awareness of visual communication through an exhibition

Science.gov (United States)

Charrière, Marie; Bogaard, Thom; Junier, Sandra; Malet, Jean-Philippe; Mostert, Erik

2014-05-01

The need to communicate about natural disasters in order to improve the awareness of communities at risk is not a matter for debate anymore. However, communication can be implemented using different media and tools, and their effectiveness may be difficult to grasp. Current research on the topic is usually focused on assessing whether communication practices meet users' needs, whereas impact assessment is mostly left out. It can be explained by difficulties arising from (1) the definition of the impact to measure, i.e. awareness, and the appropriate indicators to measure it and its variations, and (2) the implementation of a research design that allows assessing these impacts without bias. This research aims at both developing a methodology to measure risk awareness and to use it for testing the effectiveness of visual communication. The testing was conducted in the Ubaye Valley in France, an alpine area affected by multiple hazards, from December 2013 to mid-February 2014. The setting consisted of an exhibition in the public library of the main town, Barcelonnette. The main natural hazards of the study case (i.e. landslides, avalanches, flooding, debris flows and earthquakes), as well as structural and non-structural measures were presented to the general public using local examples of hazards events and mitigation. Various visualization tools were used: videos, Google earth map, interactive timeline, objects, mock-ups, technical devices as well as posters with pictures, drawings and graphs. In order to assess the effects of the exhibition on risk awareness, several groups of children and adults were submitted to a research design, consisting of 1) a pre-test, 2) the visit of the exhibition and 3) a post-test similar to the pre-test. Close-ended questions addressed the awareness indicators according to the literature, i.e. worry level, previous experiences with natural hazards events, exposure to awareness raising, ability to mitigate/respond/prepare, attitude to

Tensile and impact testing of an HFBR [High Flux Beam Reactor] control rod follower

International Nuclear Information System (INIS)

Czajkowski, C.J.; Schuster, M.H.; Roberts, T.C.; Milian, L.W.

1989-08-01

The Materials Technology Group of the Department of Nuclear Energy (DNE) at Brookhaven National Laboratory (BNL) undertook a program to machine and test specimens from a control rod follower from the High Flux Beam Reactor (HFBR). Tensile and Charpy impact specimens were machined and tested from non-irradiated aluminum alloys in addition to irradiated 6061-T6 from the HFBR. The tensile test results on irradiated material showed a two-fold increase in tensile strength to a maximum of 100.6 ksi. The impact resistance of the irradiated material showed a six-fold decrease in values (3 in-lb average) compared to similar non-irradiated material. Fracture toughness (K I ) specimens were tested on an unirradiated compositionally and dimensionally similar (to HFBR follower) 6061 T-6 material with K max values of 24.8 ± 1.0 Ksi√in (average) being obtained. The report concludes that the specimens produced during the program yielded reproducible and believable results and that proper quality assurance was provided throughout the program. 9 figs., 6 tabs

A 640 foot per second impact test of a two foot diameter model nuclear reactor containment system without fracture

Science.gov (United States)

Puthoff, R. L.

1971-01-01

An impact test was conducted on an 1142 pound 2 foot diameter sphere model. The purpose of this test was to determine the feasibility of containing the fission products of a mobile reactor in an impact. The model simulated the reactor core, energy absorbing gamma shielding, neutron shielding and the containment vessel. It was impacted against an 18,000 pound reinforced concrete block. The model was significantly deformed and the concrete block demolished. No leaks were detected nor cracks observed in the model after impact.

Held Back: The Impact of Curricular and Pedagogical Factors on Tested Achievement in High School Mathematics

Science.gov (United States)

Agvanian, Zara

2013-01-01

This study examined the impact of curricular factors and teaching practices on students' tested achievement in mathematics, explored the best predictors of the tested achievement, and examined differences in the tested achievement among student subgroups. The study utilized qualitative and quantitative methods and triangulated findings from…

An Exploration of the Impact of Accountability Testing on Teaching in Urban Elementary Classrooms

Science.gov (United States)

Bisland, Beverly Milner

2015-01-01

This study explores accountability testing in the elementary schools of New York City with particular emphasis on the impact of a statewide social studies test on the value given to social studies instruction in comparison to other subjects. The attitudes of a group of elementary teachers are examined. Some of the teachers taught all subjects in…

Low temperature impact testing of welded structural wrought iron

Science.gov (United States)

Rogers, Zachary

During the second half of the 19th century, structural wrought iron was commonly used in construction of bridges and other structures. Today, these remaining structures are still actively in use and may fall under the protection of historic preservation agencies. Continued use and protection leads to the need for inspection, maintenance, and repair of the wrought iron within these structures. Welding can be useful to achieve the appropriate repair, rehabilitation, or replacement of wrought iron members. There is currently very little published on modern welding techniques for historic wrought iron. There is also no pre-qualified method for this welding. The demand for welding in the repair of historic structural wrought iron has led to a line of research investigating shielded metal arc welding (SMAW) of historic wrought iron at the University of Colorado Denver. This prior research selected the weld type and other weld specifications to try and achieve a recognized specific welding procedure using modern SMAW technology and techniques. This thesis continues investigating SMAW of historic wrought iron. Specifically, this thesis addresses the toughness of these welds from analysis of the data collected from performing Charpy V-Notch (CVN) Impact Tests. Temperature was varied to observe the material response of the welds at low temperature. The wrought iron used in testing was from a historic vehicle bridge in Minnesota, USA. This area, and many other areas with wrought iron structures, can experience sustained or fluctuating temperatures far below freezing. Investigating the toughness of welds in historic wrought iron at these temperatures is necessary to fully understand material responses of the existing structures in need of maintenance and repair. It was shown that welded wrought iron is tougher and more ductile than non-welded wrought iron. In regards to toughness, welding is an acceptable repair method. Information on wrought iron, low temperature failure

Mechanical resistance of UO{sub 2} pellet by means of free-fall-impact testing

Energy Technology Data Exchange (ETDEWEB)

Jung, Tae-sik; Lee, Seung-jae; Kim, Jae-ik; Jo, Young-ho; Park, Bo-yong; Ko, Sang-ern [KEPCO NF, Daejeon (Korea, Republic of)

2014-10-15

A fuel rod failed during a power transient can be seen in Fig 1. and conjunction of a chipped pellet with a cladding crack has been observed in commercial reactors through the post-irradiation examinations. It revealed that missing-pellet-surface(MPS) was one of the reasons of the fuel failure. The mechanism of this failure mode that MPS induces the asymmetry of the pellet-cladding mechanical system mainly comprises a stress concentration at the inner surface resulting in non-classical PCI. The fracture toughness is largely close to material property. It is assumed that by optimizing surface design of UO{sub 2} pellet, the strength arises because theoretical strength is considerably affected by geometry as one of a parameter of factor 'f'. Pellet research for design optimization to achieve better resistance to external load should be accompanied with volumetric approach to the improvement of mechanical behavior of pellet being still ongoing. At this work, the resistance to external load is analyzed varying with the geometry of pellets and angles of impact on UO{sub 2} pellet surface by the free-fall-impact test method. The tested specimens were equivalently produced and sintered for having the same volumetric property such as sinter density and grain size expect the surface with different geometry design at the end face and shoulder which includes dish, chamfer and land in dimension and angle. Missing-pellet-surface(MPS) on UO{sub 2} pellet is inevitable behavior during manufacturing, handling and burning in reactor and brings about non-classical PCI behavior that could damage fuel rod integrity. For this reason, the free-fall-drop tester was developed by KEPCO NF Material Development laboratory in Daejeon for quantitatively investigating the mechanical behavior of UO{sub 2}. The free-fall-impact test is performed by dropping hammer on pellet shoulder with certain impact energy and at various angles. The result is quantitatively measured with weighing

The impacts of computer adaptive testing from a variety of perspectives

Directory of Open Access Journals (Sweden)

Tetsuo Kimura

2017-05-01

Full Text Available Computer adaptive testing (CAT is a kind of tailored testing, in that it is a form of computer-based testing that is adaptive to each test-taker’s ability level. In this review, the impacts of CAT are discussed from different perspectives in order to illustrate crucial points to keep in mind during the development and implementation of CAT. Test developers and psychometricians often emphasize the efficiency and accuracy of CAT in comparison to traditional linear tests. However, many test-takers report feeling discouraged after taking CATs, and this feeling can reduce learning self-efficacy and motivation. A trade-off must be made between the psychological experiences of test-takers and measurement efficiency. From the perspective of educators and subject matter experts, nonstatistical specifications, such as content coverage, content balance, and form length are major concerns. Thus, accreditation bodies may be faced with a discrepancy between the perspectives of psychometricians and those of subject matter experts. In order to improve test-takers’ impressions of CAT, the author proposes increasing the target probability of answering correctly in the item selection algorithm even if doing so consequently decreases measurement efficiency. Two different methods, CAT with a shadow test approach and computerized multistage testing, have been developed in order to ensure the satisfaction of subject matter experts. In the shadow test approach, a full-length test is assembled that meets the constraints and provides maximum information at the current ability estimate, while computerized multistage testing gives subject matter experts an opportunity to review all test forms prior to administration.

Test Report for MSFC Test No. 83-2: Pressure scaled water impact test of a 12.5 inch diameter model of the Space Shuttle solid rocket booster filament wound case and external TVC PCD

Science.gov (United States)

1983-01-01

Water impact tests using a 12.5 inch diameter model representing a 8.56 percent scale of the Space Shuttle Solid Rocket Booster configuration were conducted. The two primary objectives of this SRB scale model water impact test program were: 1. Obtain cavity collapse applied pressure distributions for the 8.56 percent rigid body scale model FWC pressure magnitudes as a function of full-scale initial impact conditions at vertical velocities from 65 to 85 ft/sec, horizontal velocities from 0 to 45 ft/sec, and angles from -10 to +10 degrees. 2. Obtain rigid body applied pressures on the TVC pod and aft skirt internal stiffener rings at initial impact and cavity collapse loading events. In addition, nozzle loads were measured. Full scale vertical velocities of 65 to 85 ft/sec, horizontal velocities of 0 to 45 ft/sec, and impact angles from -10 to +10 degrees simulated.

Shock Induced Melting in Aluminum: Wave Profile Measurements

Energy Technology Data Exchange (ETDEWEB)

Chhabildas, Lalit C.; Furnish, Michael D.; Reinhart, William D.

1999-06-23

We have developed launch capabilities that can propel macroscopic plates to hypervelocities (8 to 16 km/s). This capability has been used to determine the first time-resolved wave profile measurements using velocity interferometry techniques at impact velocities of 10 km/s. These measurements show that alu- minum continues to exhibit normal release behavior to 161 GPa with complete loss of strength in the shocked state. Results of these experiments are discussed and compared with the results of lower pressure experi- ments conducted at lower impact velocities.

Understanding the impact of genetic testing for inherited retinal dystrophy.

Science.gov (United States)

Combs, Ryan; McAllister, Marion; Payne, Katherine; Lowndes, Jo; Devery, Sophie; Webster, Andrew R; Downes, Susan M; Moore, Anthony T; Ramsden, Simon; Black, Graeme; Hall, Georgina

2013-11-01

The capability of genetic technologies is expanding rapidly in the field of inherited eye disease. New genetic testing approaches will deliver a step change in the ability to diagnose and extend the possibility of targeted treatments. However, evidence is lacking about the benefits of genetic testing to support service planning. Here, we report qualitative data about retinal dystrophy families' experiences of genetic testing in United Kingdom. The data were part of a wider study examining genetic eye service provision. Twenty interviewees from families in which a causative mutation had been identified by a genetic eye clinic were recruited to the study. Fourteen interviewees had chosen to have a genetic test and five had not; one was uncertain. In-depth telephone interviews were conducted allowing a thorough exploration of interviewees' views and experiences of the benefits of genetic counselling and testing. Transcripts were analysed using thematic analysis. Both affected and unaffected interviewees expressed mainly positive views about genetic testing, highlighting benefits such as diagnostic confirmation, risk information, and better preparation for the future. Negative consequences included the burden of knowledge, moral dilemmas around reproduction, and potential impact on insurance. The offer of genetic testing was often taken up, but was felt unnecessary in some cases. Interviewees in the study reported many benefits, suggesting genetic testing should be available to this patient group. The benefits and risks identified will inform future evaluation of models of service delivery. This research was part of a wider study exploring experiences of families with retinal dystrophy.

Impact of family language and testing language on reading performance in a bilingual educational context.

Science.gov (United States)

Elosua Oliden, Paula; Mujika Lizaso, Josu

2014-01-01

When different languages co-exist in one area, or when one person speaks more than one language, the impact of language on psychological and educational assessment processes can be considerable. The aim of this work was to study the impact of testing language in a community with two official languages: Spanish and Basque. By taking the PISA 2009 Reading Comprehension Test as a basis for analysis, four linguistic groups were defined according to the language spoken at home and the test language. Psychometric equivalence between test forms and differences in results among the four language groups were analyzed. The comparison of competence means took into account the effects of the index of socioeconomic and cultural status (ISEC) and gender. One reading unit with differential item functioning was detected. The reading competence means were considerably higher in the monolingual Spanish-Spanish group. No differences were found between the language groups based on family language when the test was conducted in Basque. The study illustrates the importance of taking into account psychometric, linguistic and sociolinguistic factors in linguistically diverse assessment contexts.

Testing of the Impact Load and Tribological Behaviour of W-C:H Hard Composite Coatings

Czech Academy of Sciences Publication Activity Database

Fořt, Tomáš; Vítů, T.; Novák, R.; Grossman, Jan; Sobota, Jaroslav; Vyskočil, J.

2011-01-01

Roč. 105, č. 14 (2011), s102-s104 ISSN 0009-2770 R&D Projects: GA MPO 2A-1TP1/031 Institutional research plan: CEZ:AV0Z20650511 Keywords : PVD * DLC * impact test * pin-on-disc * friction coefficient Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 0.529, year: 2011

A Ballistic Limit Analysis Program for Shielding Against Micrometeoroids and Orbital Debris

Science.gov (United States)

Ryan, Shannon; Christiansen, Erie

2010-01-01

A software program has been developed that enables the user to quickly and simply perform ballistic limit calculations for common spacecraft structures that are subject to hypervelocity impact of micrometeoroid and orbital debris (MMOD) projectiles. This analysis program consists of two core modules: design, and; performance. The design module enables a user to calculate preliminary dimensions of a shield configuration (e.g., thicknesses/areal densities, spacing, etc.) for a ?design? particle (diameter, density, impact velocity, incidence). The performance module enables a more detailed shielding analysis, providing the performance of a user-defined shielding configuration over the range of relevant in-orbit impact conditions.

An 810 ft/sec soil impact test of a 2-foot diameter model nuclear reactor containment system

Science.gov (United States)

Puthoff, R. L.

1972-01-01

A soil impact test was conducted on a 880-pound 2-foot diameter sphere model. The impact area consisted of back filled desert earth and rock. The impact generated a crater 5 feet in diameter by 5 feet deep. It buried itself a total of 15 feet - as measured to the bottom of the model. After impact the containment vessel was pressure checked. No leaks were detected nor cracks observed.

IMPACT_S: integrated multiprogram platform to analyze and combine tests of selection.

Directory of Open Access Journals (Sweden)

Emanuel Maldonado

Full Text Available Among the major goals of research in evolutionary biology are the identification of genes targeted by natural selection and understanding how various regimes of evolution affect the fitness of an organism. In particular, adaptive evolution enables organisms to adapt to changing ecological factors such as diet, temperature, habitat, predatory pressures and prey abundance. An integrative approach is crucial for the identification of non-synonymous mutations that introduce radical changes in protein biochemistry and thus in turn influence the structure and function of proteins. Performing such analyses manually is often a time-consuming process, due to the large number of statistical files generated from multiple approaches, especially when assessing numerous taxa and/or large datasets. We present IMPACT_S, an easy-to-use Graphical User Interface (GUI software, which rapidly and effectively integrates, filters and combines results from three widely used programs for assessing the influence of selection: Codeml (PAML package, Datamonkey and TreeSAAP. It enables the identification and tabulation of sites detected by these programs as evolving under the influence of positive, neutral and/or negative selection in protein-coding genes. IMPACT_S further facilitates the automatic mapping of these sites onto the three-dimensional structures of proteins. Other useful tools incorporated in IMPACT_S include Jmol, Archaeopteryx, Gnuplot, PhyML, a built-in Swiss-Model interface and a PDB downloader. The relevance and functionality of IMPACT_S is shown through a case study on the toxicoferan-reptilian Cysteine-rich Secretory Proteins (CRiSPs. IMPACT_S is a platform-independent software released under GPLv3 license, freely available online from http://impact-s.sourceforge.net.

IMPACT_S: integrated multiprogram platform to analyze and combine tests of selection.

Science.gov (United States)

Maldonado, Emanuel; Sunagar, Kartik; Almeida, Daniela; Vasconcelos, Vitor; Antunes, Agostinho

2014-01-01

Among the major goals of research in evolutionary biology are the identification of genes targeted by natural selection and understanding how various regimes of evolution affect the fitness of an organism. In particular, adaptive evolution enables organisms to adapt to changing ecological factors such as diet, temperature, habitat, predatory pressures and prey abundance. An integrative approach is crucial for the identification of non-synonymous mutations that introduce radical changes in protein biochemistry and thus in turn influence the structure and function of proteins. Performing such analyses manually is often a time-consuming process, due to the large number of statistical files generated from multiple approaches, especially when assessing numerous taxa and/or large datasets. We present IMPACT_S, an easy-to-use Graphical User Interface (GUI) software, which rapidly and effectively integrates, filters and combines results from three widely used programs for assessing the influence of selection: Codeml (PAML package), Datamonkey and TreeSAAP. It enables the identification and tabulation of sites detected by these programs as evolving under the influence of positive, neutral and/or negative selection in protein-coding genes. IMPACT_S further facilitates the automatic mapping of these sites onto the three-dimensional structures of proteins. Other useful tools incorporated in IMPACT_S include Jmol, Archaeopteryx, Gnuplot, PhyML, a built-in Swiss-Model interface and a PDB downloader. The relevance and functionality of IMPACT_S is shown through a case study on the toxicoferan-reptilian Cysteine-rich Secretory Proteins (CRiSPs). IMPACT_S is a platform-independent software released under GPLv3 license, freely available online from http://impact-s.sourceforge.net.

HIV Testing Among Young People Aged 16-24 in South Africa: Impact of Mass Media Communication Programs.

Science.gov (United States)

Do, Mai; Figueroa, Maria Elena; Lawrence Kincaid, D

2016-09-01

Knowing one's serostatus is critical in the HIV prevention, care and treatment continuum. This study examines the impact of communication programs on HIV testing in South Africa. Data came from 2204 young men and women aged 16-24 who reported to be sexually active in a population based survey. Structural equation modeling was used to test the directions and causal pathways between communication program exposure, HIV testing discussion, and having a test in the last 12 months. Bivariate and multivariate probit regressions provided evidence of exogeneity of communication exposure and the two HIV-related outcomes. One in three sampled individuals had been tested in the last 12 months. Communication program exposure only had an indirect effect on getting tested by encouraging young people to talk about testing. The study suggests that communication programs may create an environment that supports open HIV-related discussions and may have a long-term impact on behavior change.

Dynamic Impact Analysis and Test of Concrete Overpack Segment Models

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang Hoon; Kim, Ki Young; Jeon, Je Eon; Seo, Ki Seog [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-10-15

Concrete cask is an option for spent nuclear fuel interim storage which is used mainly in US. The concrete overpack of the cask provides radiation shielding as well as physical protection for inner canister against external mechanical shock. When the overpack undergoes a severe missile impact which might be caused by tornado or aircraft crash, it should sustain minimal level of structural integrity so that the radiation shielding and the retrievability of canister are maintained. Empirical formulas have been developed for the evaluation of concrete damage but those formulas can be used only for local damage evaluation and not for global damage evaluation. In this research, a series of numerical simulations and tests have been performed to evaluate the damage of two types of concrete overpack segment models under high speed missile impact. It is shown that appropriate modeling of material failure is crucial in this kind of analyses and finding the correct failure parameters may not be straightforward

Impacts Analyses Supporting the National Environmental Policy Act Environmental Assessment for the Resumption of Transient Testing Program

Energy Technology Data Exchange (ETDEWEB)

Schafer, Annette L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Brown, LLoyd C. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Carathers, David C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Christensen, Boyd D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Dahl, James J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Miller, Mark L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Farnum, Cathy Ottinger [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Peterson, Steven [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sondrup, A. Jeffrey [Idaho National Lab. (INL), Idaho Falls, ID (United States); Subaiya, Peter V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wachs, Daniel M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Weiner, Ruth F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2014-02-01

This document contains the analysis details and summary of analyses conducted to evaluate the environmental impacts for the Resumption of Transient Fuel and Materials Testing Program. It provides an assessment of the impacts for the two action alternatives being evaluated in the environmental assessment. These alternatives are (1) resumption of transient testing using the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory (INL) and (2) conducting transient testing using the Annular Core Research Reactor (ACRR) at Sandia National Laboratory in New Mexico (SNL/NM). Analyses are provided for radiologic emissions, other air emissions, soil contamination, and groundwater contamination that could occur (1) during normal operations, (2) as a result of accidents in one of the facilities, and (3) during transport. It does not include an assessment of the biotic, cultural resources, waste generation, or other impacts that could result from the resumption of transient testing. Analyses were conducted by technical professionals at INL and SNL/NM as noted throughout this report. The analyses are based on bounding radionuclide inventories, with the same inventories used for test materials by both alternatives and different inventories for the TREAT Reactor and ACRR. An upper value on the number of tests was assumed, with a test frequency determined by the realistic turn-around times required between experiments. The estimates provided for impacts during normal operations are based on historical emission rates and projected usage rates; therefore, they are bounding. Estimated doses for members of the public, collocated workers, and facility workers that could be incurred as a result of an accident are very conservative. They do not credit safety systems or administrative procedures (such as evacuation plans or use of personal protective equipment) that could be used to limit worker doses. Doses estimated for transportation are conservative and are based on

Putting social impact assessment to the test as a method for implementing responsible tourism practice

International Nuclear Information System (INIS)

McCombes, Lucy; Vanclay, Frank; Evers, Yvette

2015-01-01

The discourse on the social impacts of tourism needs to shift from the current descriptive critique of tourism to considering what can be done in actual practice to embed the management of tourism's social impacts into the existing planning, product development and operational processes of tourism businesses. A pragmatic approach for designing research methodologies, social management systems and initial actions, which is shaped by the real world operational constraints and existing systems used in the tourism industry, is needed. Our pilot study with a small Bulgarian travel company put social impact assessment (SIA) to the test to see if it could provide this desired approach and assist in implementing responsible tourism development practice, especially in small tourism businesses. Our findings showed that our adapted SIA method has value as a practical method for embedding a responsible tourism approach. While there were some challenges, SIA proved to be effective in assisting the staff of our test case tourism business to better understand their social impacts on their local communities and to identify actions to take. - Highlights: • Pragmatic approach is needed for the responsible management of social impacts of tourism. • Our adapted Social impact Assessment (SIA) method has value as a practical method. • SIA can be embedded into tourism businesses existing ‘ways of doing things’. • We identified challenges and ways to improve our method to better suit small tourism business context

Putting social impact assessment to the test as a method for implementing responsible tourism practice

Energy Technology Data Exchange (ETDEWEB)

McCombes, Lucy, E-mail: l.mccombes@leedsbeckett.ac.uk [International Centre for Research in Events, Tourism and Hospitality (ICRETH), Leeds Beckett University, Headingley Campus, Macaulay Hall 103, Leeds LS6 3QS (United Kingdom); Vanclay, Frank, E-mail: frank.vanclay@rug.nl [Professor of Cultural Geography, Faculty of Spatial Sciences, University of Groningen, PO Box 800, 9700AV Groningen (Netherlands); Evers, Yvette, E-mail: y.evers@tft-earth.org [The Forest Trust, Chemin de Chantavril 2, 1260 Nyon (Switzerland)

2015-11-15

The discourse on the social impacts of tourism needs to shift from the current descriptive critique of tourism to considering what can be done in actual practice to embed the management of tourism's social impacts into the existing planning, product development and operational processes of tourism businesses. A pragmatic approach for designing research methodologies, social management systems and initial actions, which is shaped by the real world operational constraints and existing systems used in the tourism industry, is needed. Our pilot study with a small Bulgarian travel company put social impact assessment (SIA) to the test to see if it could provide this desired approach and assist in implementing responsible tourism development practice, especially in small tourism businesses. Our findings showed that our adapted SIA method has value as a practical method for embedding a responsible tourism approach. While there were some challenges, SIA proved to be effective in assisting the staff of our test case tourism business to better understand their social impacts on their local communities and to identify actions to take. - Highlights: • Pragmatic approach is needed for the responsible management of social impacts of tourism. • Our adapted Social impact Assessment (SIA) method has value as a practical method. • SIA can be embedded into tourism businesses existing ‘ways of doing things’. • We identified challenges and ways to improve our method to better suit small tourism business context.

Evaluation of impact limiter performance during end-on and slapdown drop tests of a one-third scale model storage/transport cask system

International Nuclear Information System (INIS)

Yoshimura, H.R.; Bronowski, D.R.; Uncapher, W.L.; Attaway, S.W.; Bateman, V.I.; Carne, T.G.; Gregory, D.L.; Huerta, M.

1990-12-01

This report describes drop testing of a one-third scale model shipping cask system. Two casks were designed and fabricated by Transnuclear, Inc., to ship spent fuel from the former Nuclear Fuel Services West Valley reprocessing facility in New York to the Idaho National Engineering Laboratory for a long-term spent fuel dry storage demonstration project. As part of the NRC's regulatory certification process, one-third scale model tests were performed to obtain experimental data on impact limiter performance during impact testing. The objectives of the testing program were to (1) obtain deceleration and displacement information for the cask and impact limiter system, (2) obtain dynamic force-displacement data for the impact limiters, (3) verify the integrity of the impact limiter retention system, and (4) examine the crush behavior of the limiters. Two 30-ft (9-m) drop tests were conducted on a mass model of the cask body and scaled balsa and redwood-filled impact limiters. This report describes the results of both tests in terms of measured decelerations, posttest deformation measurements, and the general structural response of the system. 3 refs., 32 figs

Impact of Vaccination History on Serological Testing in Pregnant Women.

Science.gov (United States)

Desjardins, Michaël; Boucoiran, Isabelle; Paquet, Caroline; Laferrière, Céline; Gosselin-Brisson, Anne; Labbé, Annie-Claude; Martel-Laferrière, Valérie

2018-04-01

Serological testing guidelines for vaccine-preventable infectious diseases in pregnant women are heterogeneous. It is unclear how vaccination history influences health care workers' (HCWs) attitudes about testing. The aim of this study was to describe current practices in screening for rubella, hepatitis B, and varicella-zoster virus (VZV) in pregnant women in the province of Québec. In 2015, an electronic survey was distributed to HCWs who followed the case of at least one pregnant woman in the previous year and who could be contacted by email by their professional association. A total of 363 of 1084 (33%) participants were included in the analysis: general practitioners (57%), obstetrician-gynaecologists (20%), midwives (41%), and nurse practitioners (31%). For rubella, 48% of participants inquired about vaccination status, and of these, 98% offered serological testing for unvaccinated women versus 44% for vaccinated women. Similarly, of the 48% of participants who asked about hepatitis B vaccination status before offering testing, 96% ordered testing for hepatitis B surface antigen, 28% ordered testing for hepatitis B surface antibody, and 1% ordered no serological testing to unvaccinated women versus 72%, 46%, and 8%, respectively, for vaccinated women. Among the 81% of respondents who discussed VZV during prenatal care, 13% ordered serological testing if patients had a history of VZV infection, 87% if the VZV history was uncertain, and 19% if patients had a positive history of vaccination. Asking about vaccination status influences HCWs' attitudes about serological testing for rubella, hepatitis B, and VZV. In the context of increasing vaccination coverage in women of child-bearing age, it is important to clarify the impact of vaccination status in serological screening guidelines in pregnant women. Copyright © 2018 Society of Obstetricians and Gynaecologists of Canada. Published by Elsevier Inc. All rights reserved.

Acoustic Emission Monitoring of Lightning-Damaged CFRP Laminates during Compression-after-Impact Test

Energy Technology Data Exchange (ETDEWEB)

Kwon, Oh Yang; Shin, Jae Ha [Department of Mechanical Engineering, Inha University, Incheon (Korea, Republic of)

2012-06-15

Carbon-fiber reinforced plastic(CFRP) laminates made of nano-particle-coated carbon fibers and damaged by a simulated lightning strike were tested under compression-after-impact(CAI) mode, during which the damage progress due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. Conductive nano-particles were coated directly on the fibers, from which CFRP coupons were made. The coupon were subjected to the strikes with a high voltage/current impulse of 10-40 kA within a few . The effects of nano-particle coating and the degree of damage induced by the simulated lightning strikes on AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terms of damage area by using ultrasonic C-scan images. The assessment during the CAI tests of damaged CFRP showed that AE monitoring appeared to be useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes.

The Impact of Time-Series Diagnostic Tests on the Writing Ability of Iranian EFL Learners

Science.gov (United States)

Atashgahi, Bahareh Molazem

2014-01-01

This study aimed to show whether administering a battery of time-series diagnostic tests (screening) has any impact on Iranian EFL learners' writing ability. The study was conducted on the intermediate EFL learners at Islamic Azad University North Tehran branch. The researcher administered a homogenizing test in order to exclude the exceptional…

Simulation analysis of impact tests of steel plate reinforced concrete and reinforced concrete slabs against aircraft impact and its validation with experimental results

International Nuclear Information System (INIS)

Sadiq, Muhammad; Xiu Yun, Zhu; Rong, Pan

2014-01-01

Highlights: • Simulation analysis is carried out with two constitutive concrete models. • Winfrith model can better simulate nonlinear response of concrete than CSCM model. • Performance of steel plate concrete is better than reinforced concrete. • Thickness of safety related structures can be reduced by adopting steel plates. • Analysis results, mainly concrete material models should be validated. - Abstract: The steel plate reinforced concrete and reinforced concrete structures are used in nuclear power plants for protection against impact of an aircraft. In order to compare the impact resistance performance of steel plate reinforced concrete and reinforced concrete slabs panels, simulation analysis of 1/7.5 scale model impact tests is carried out by using finite element code ANSYS/LS-DYNA. The damage modes of all finite element models, velocity time history curves of the aircraft engine and damage to aircraft model are compared with the impact test results of steel plate reinforced concrete and reinforced concrete slab panels. The results indicate that finite element simulation results correlate well with the experimental results especially for constitutive winfrith concrete model. Also, the impact resistance performance of steel plate reinforced concrete slab panels is better than reinforced concrete slab panels, particularly the rear face steel plate is very effective in preventing the perforation and scabbing of concrete than conventional reinforced concrete structures. In this way, the thickness of steel plate reinforced concrete structures can be reduced in important structures like nuclear power plants against impact of aircraft. It also demonstrates the methodology to validate the analysis procedure with experimental and analytical studies. It may be effectively employed to predict the precise response of safety related structures against aircraft impact

Prediction of psychological functioning one year after the predictive test for Huntington's disease and impact of the test result on reproductive decision making.

Science.gov (United States)

Decruyenaere, M; Evers-Kiebooms, G; Boogaerts, A; Cassiman, J J; Cloostermans, T; Demyttenaere, K; Dom, R; Fryns, J P; Van den Berghe, H

1996-01-01

For people at risk for Huntington's disease, the anxiety and uncertainty about the future may be very burdensome and may be an obstacle to personal decision making about important life issues, for example, procreation. For some at risk persons, this situation is the reason for requesting predictive DNA testing. The aim of this paper is two-fold. First, we want to evaluate whether knowing one's carrier status reduces anxiety and uncertainty and whether it facilitates decision making about procreation. Second, we endeavour to identify pretest predictors of psychological adaptation one year after the predictive test (psychometric evaluation of general anxiety, depression level, and ego strength). The impact of the predictive test result was assessed in 53 subjects tested, using pre- and post-test psychometric measurement and self-report data of follow up interviews. Mean anxiety and depression levels were significantly decreased one year after a good test result; there was no significant change in the case of a bad test result. The mean personality profile, including ego strength, remained unchanged one year after the test. The study further shows that the test result had a definite impact on reproductive decision making. Stepwise multiple regression analyses were used to select the best predictors of the subject's post-test reactions. The results indicate that a careful evaluation of pretest ego strength, depression level, and coping strategies may be helpful in predicting post-test reactions, independently of the carrier status. Test result (carrier/ non-carrier), gender, and age did not significantly contribute to the prediction. About one third of the variance of post-test anxiety and depression level and more than half of the variance of ego strength was explained, implying that other psychological or social aspects should also be taken into account when predicting individual post-test reactions. PMID:8880572

Galileo battery testing and the impact of test automation

Science.gov (United States)

Pertuch, W. T.; Dils, C. T.

1985-01-01

Test complexity, changes of test specifications, and the demand for tight control of tests led to the development of automated testing used for Galileo and other projects. The use of standardized interfacing, i.e., IEEE-488, with desktop computers and test instruments, resulted in greater reliability, repeatability, and accuracy of both control and data reporting. Increased flexibility of test programming has reduced costs by permitting a wide spectrum of test requirements at one station rather than many stations.

Review of Evidence of Environmental Impacts of Animal Research and Testing

OpenAIRE

Katherine Groff; Eric Bachli; Molly Lansdowne; Theodora Capaldo

2014-01-01

Millions of animals are used in research and toxicity testing, including in drug, medical device, chemical, cosmetic, personal care, household, and other product sectors, but the environmental consequences are yet to be adequately addressed. Evidence suggests that their use and disposal, and the associated use of chemicals and supplies, contribute to pollution as well as adverse impacts on biodiversity and public health. The objective of this review is to examine such evidence. The review in...

Development of a tornado safe room door from wood Products: door design and impact testing

Science.gov (United States)

Robert H. Falk; James J. Bridwell

2016-01-01

In this study, a tornado safe room door built from wood products and steel sheeting was developed and impact-tested according to tornado safe room standards. Results indicate that an door constructed from as few as two sheets of 23/32-in. (18.26-mm) construction-grade plywood and overlaid with 18-gauge (0.05-in.- (1.27- mm-) thick) steel can pass the required impact...

Dynamic Impact Testing and Model Development in Support of NASA's Advanced Composites Program

Science.gov (United States)

Melis, Matthew E.; Pereira, J. Michael; Goldberg, Robert; Rassaian, Mostafa

2018-01-01

The purpose of this paper is to provide an executive overview of the HEDI effort for NASA's Advanced Composites Program and establish the foundation for the remaining papers to follow in the 2018 SciTech special session NASA ACC High Energy Dynamic Impact. The paper summarizes the work done for the Advanced Composites Program to advance our understanding of the behavior of composite materials during high energy impact events and to advance the ability of analytical tools to provide predictive simulations. The experimental program carried out at GRC is summarized and a status on the current development state for MAT213 will be provided. Future work will be discussed as the HEDI effort transitions from fundamental analysis and testing to investigating sub-component structural concept response to impact events.

Lab-scale impact test to investigate the pipe-soil interaction and comparative study to evaluate structural responses

Directory of Open Access Journals (Sweden)

Dong-Man Ryu

2015-07-01

Full Text Available This study examined the dynamic response of a subsea pipeline under an impact load to determine the effect of the seabed soil. A laboratory-scale soil-based pipeline impact test was carried out to investigate the pipeline deformation/strain as well as the interaction with the soil-pipeline. In addition, an impact test was simulated using the finite element technique, and the calculated strain was compared with the experimental results. During the simulation, the pipeline was described based on an elasto-plastic analysis, and the soil was modeled using the Mohr-Coulomb fail-ure criterion. The results obtained were compared with ASME D31.8, and the differences between the analysis results and the rules were specifically investigated. Modified ASME formulae were proposed to calculate the precise structural behavior of a subsea pipeline under an impact load when considering sand- and clay-based seabed soils.

Normalization of Impact Energy by Laminate Thickness for Compression After Impact Testing

Science.gov (United States)

Nettles, A. T.; Hromisin, S. M.

2013-01-01

The amount of impact energy used to damage a composite laminate is a critical parameter when assessing residual strength properties. The compression after impact (CAI) strength of impacted laminates is dependent upon how thick the laminate is and this has traditionally been accounted for by normalizing (dividing) the impact energy by the laminate's thickness. However, when comparing CAI strength values for a given lay-up sequence and fiber/resin system, dividing the impact energy by the specimen thickness has been noted by the author to give higher CAI strength values for thicker laminates. A study was thus undertaken to assess the comparability of CAI strength data by normalizing the impact energy by the specimen thickness raised to a power to account for the higher strength of thicker laminates. One set of data from the literature and two generated in this study were analyzed by dividing the impact energy by the specimen thickness to the 1, 1.5, 2, and 2.5 powers. Results show that as laminate thickness and damage severity decreased, the value which the laminate thickness needs to be raised to in order to yield more comparable CAI data increases.

Testing the Impact of a Pre-Instructional Digital Game on Middle-Grade Students' Understanding of Photosynthesis

Science.gov (United States)

Culp, Katherine McMillan; Martin, Wendy; Clements, Margaret; Lewis Presser, Ashley

2015-01-01

Rigorous studies of the impact of digital games on student learning remain relatively rare, as do studies of games as supports for learning difficult, core curricular concepts in the context of normal classroom practices. This study uses a blocked, cluster randomized controlled trial design to test the impact of a digital game, played as homework…

Evaluating the test-retest reliability of symptom indices associated with the ImPACT post-concussion symptom scale (PCSS).

Science.gov (United States)

Merritt, Victoria C; Bradson, Megan L; Meyer, Jessica E; Arnett, Peter A

2018-05-01

The Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) is a commonly used tool in sports concussion assessment. While test-retest reliabilities have been established for the ImPACT cognitive composites, few studies have evaluated the psychometric properties of the ImPACT's Post-Concussion Symptom Scale (PCSS). The purpose of this study was to establish the test-retest reliability of symptom indices associated with the PCSS. Participants included 38 undergraduate students (50.0% male) who underwent neuropsychological testing as part of their participation in their psychology department's research subject pool. The majority of the participants were Caucasian (94.7%) and had no history of concussion (73.7%). All participants completed the ImPACT at two time points, approximately 6 weeks apart. The PCSS was the main outcome measure, and eight symptom indices were calculated (a total symptom score, three symptom summary indices, and four symptom clusters). Pearson correlations (r) and intraclass correlation coefficients (ICCs) were computed as measures of test-retest reliability. Overall, reliabilities ranged from low to high (r = .44 to .80; ICC = .44 to .77). The cognitive symptom cluster exhibited the highest test-retest reliability (r = .80, ICC = .77), followed by the positive symptom total (PST) index, an indicator of the total number of symptoms endorsed (r = .71, ICC = .69). In contrast, the commonly used total symptom score showed lower test-retest reliability (r = .67, ICC = .62). Paired-samples t tests revealed no significant differences between test and retest for any of the symptom variables (all p > .01). Finally, reliable change indices (RCI) were computed to determine whether differences observed between test and retest represented clinically significant change. RCI values were provided for each symptom index at the 80%, 90%, and 95% confidence intervals. These results suggest that evaluating additional symptom

An investigation on impacts of scheduling configurations on Mississippi biology subject area testing

Science.gov (United States)

Marchette, Frances Lenora

The purpose of this mixed modal study was to compare the results of Biology Subject Area mean scores of students on a 4 x 4 block schedule, A/B block schedule, and traditional year-long schedule for 1A to 5A size schools. This study also reviewed the data to determine if minority or gender issues might influence the test results. Interviews with administrators and teachers were conducted about the type of schedule configuration they use and the influence that the schedule has on student academic performance on the Biology Subject Area Test. Additionally, this research further explored whether schedule configurations allow sufficient time for students to construct knowledge. This study is important to schools, teachers, and administrators because it can assist them in considering the impacts that different types of class schedules have on student performance and if ethnic or gender issues are influencing testing results. This study used the causal-comparative method for the quantitative portion of the study and constant comparative method for the qualitative portion to explore the relationship of school schedules on student academic achievement on the Mississippi Biology Subject Area Test. The aggregate means of selected student scores indicate that the Mississippi Biology Subject Area Test as a measure of student performance reveals no significant difference on student achievement for the three school schedule configurations. The data were adjusted for initial differences of gender, minority, and school size on the three schedule configurations. The results suggest that schools may employ various schedule configurations and expect student performance on the Mississippi Biology Subject Area Test to be unaffected. However, many areas of concern were identified in the interviews that might impact on school learning environments. These concerns relate to effective classroom management, the active involvement of students in learning, the adequacy of teacher education

Study of austenitic stainless steel welded with low alloy steel filler metal. [tensile and impact strength tests

Science.gov (United States)

Burns, F. A.; Dyke, R. A., Jr.

1979-01-01

The tensile and impact strength properties of 316L stainless steel plate welded with low alloy steel filler metal were determined. Tests were conducted at room temperature and -100 F on standard test specimens machined from as-welded panels of various chemical compositions. No significant differences were found as the result of variations in percentage chemical composition on the impact and tensile test results. The weldments containing lower chromium and nickel as the result of dilution of parent metal from the use of the low alloy steel filler metal corroded more severely in a marine environment. The use of a protective finish, i.e., a nitrile-based paint containing aluminum powder, prevented the corrosive attack.

Change of notch impact strength depending on radiation dose and test temperature

Directory of Open Access Journals (Sweden)

Martin Bednarik

2017-01-01

Full Text Available The main purpose of this paper has been determine the effect of radiation crosslinking on the notch impact strength of polyamides filled with fiberglass. These properties were examined in dependence on the dosage of the ionizing beta radiation (non-irradiated samples and those irradiated by dosage 66 and 132 kGy were compared and on the test temperature (23–150 °C.

A prospective study of the psychosocial impact of a positive Chlamydia trachomatis laboratory test.

Science.gov (United States)

Gottlieb, Sami L; Stoner, Bradley P; Zaidi, Akbar A; Buckel, Christina; Tran, Molly; Leichliter, Jami S; Berman, Stuart M; Markowitz, Lauri E

2011-11-01

Few data exist on potential harms of chlamydia screening. We assessed the psychosocial impact of receiving a positive Chlamydia trachomatis test result. We prospectively studied women ≥16 years of age undergoing chlamydia testing in 2 Midwestern family planning clinics. We surveyed women at baseline and about 1 month after receiving test results, using 9 validated psychosocial scales/subscales and chlamydia-specific questions. Changes in scale scores were calculated for each woman. Mean percent changes in scores for chlamydia-positive and -negative women were compared using a t test. We enrolled 1807 women (response rate, 84%). Of the 1688 women with test results, 149 (8.8%) tested positive. At follow-up, chlamydia-positive women (n = 71) had a 75% increase in anxiety about sexual aspects of their life on the Multidimensional Sexual Self-Concept Questionnaire (P < 0.001), significantly greater than the 26% increase among 280 randomly selected chlamydia-negative women (P = 0.02). There were no differences for the other 8 scales/subscales, including general measures of anxiety, depression, and self-esteem. Chlamydia-positive women were more likely than chlamydia-negative women to be "concerned about chlamydia" (80% vs. 40%, P < 0.001) and to report breaking up with a main partner (33% vs. 11%, P < 0.001) at follow-up. Women testing positive reported a range of chlamydia-specific concerns. Chlamydia-positive women had significant increases in anxiety about sex and concern about chlamydia, but did not have marked changes in more general measures of psychosocial well-being about 1 month after diagnosis. Chlamydia diagnoses were associated with some disruption of relationships with main partners. Chlamydia-specific concerns may guide counseling messages to minimize psychosocial impact.

Evaluation of Dynamic Deformation Behaviors in Metallic Materials under High Strain-Rates Using Taylor Bar Impact Test

Energy Technology Data Exchange (ETDEWEB)

Bae, Kyung Oh; Shin, Hyung Seop [Andong National Univ., Andong (Korea, Republic of)

2016-09-15

To ensure the reliability and safety of various mechanical systems in accordance with their high-speed usage, it is necessary to evaluate the dynamic deformation behavior of structural materials under impact load. However, it is not easy to understand the dynamic deformation behavior of the structural materials using experimental methods in the high strain-rate range exceeding 10{sup 4} s{sup -1}. In this study, the Taylor bar impact test was conducted to investigate the dynamic deformation behavior of metallic materials in the high strain-rate region, using a high-speed photography system. Numerical analysis of the Taylor bar impact test was performed using AUTODYN S/W. The results of the analysis were compared with the experimental results, and the material behavior in the high strain-rate region was discussed.

Explaining the black-white gap in cognitive test scores: Toward a theory of adverse impact.

Science.gov (United States)

Cottrell, Jonathan M; Newman, Daniel A; Roisman, Glenn I

2015-11-01

In understanding the causes of adverse impact, a key parameter is the Black-White difference in cognitive test scores. To advance theory on why Black-White cognitive ability/knowledge test score gaps exist, and on how these gaps develop over time, the current article proposes an inductive explanatory model derived from past empirical findings. According to this theoretical model, Black-White group mean differences in cognitive test scores arise from the following racially disparate conditions: family income, maternal education, maternal verbal ability/knowledge, learning materials in the home, parenting factors (maternal sensitivity, maternal warmth and acceptance, and safe physical environment), child birth order, and child birth weight. Results from a 5-wave longitudinal growth model estimated on children in the NICHD Study of Early Child Care and Youth Development from ages 4 through 15 years show significant Black-White cognitive test score gaps throughout early development that did not grow significantly over time (i.e., significant intercept differences, but not slope differences). Importantly, the racially disparate conditions listed above can account for the relation between race and cognitive test scores. We propose a parsimonious 3-Step Model that explains how cognitive test score gaps arise, in which race relates to maternal disadvantage, which in turn relates to parenting factors, which in turn relate to cognitive test scores. This model and results offer to fill a need for theory on the etiology of the Black-White ethnic group gap in cognitive test scores, and attempt to address a missing link in the theory of adverse impact. (c) 2015 APA, all rights reserved).

Spacecraft charging and related effects during Halley encounter

International Nuclear Information System (INIS)

Young, D.T.

1983-01-01

Hypervelocity (69 km/s) impact of cometary material with surfaces of the GIOTTO spacecraft will induce a number of spurious and possibly harmful phenomena. The most serious of these is likely to be spacecraft charging that results from impact-produced plasma distributions surrounding GIOTTO. The ESA Plasma Environment Working Group, whose studies are the basis for this report, finds that charging may become significant within approx. 10 5 km of the nucleus where potentials of approx. = +20 V are to be expected. In addition to spacecraft charging, impact produced plasma may interfere with in situ plasma measurements, particularly those of ion plasma analyzers and mass spectrometers

Impact of a personal CYP2D6 testing workshop on physician assistant student attitudes toward pharmacogenetics.

Science.gov (United States)

O'Brien, Travis J; LeLacheur, Susan; Ward, Caitlin; Lee, Norman H; Callier, Shawneequa; Harralson, Arthur F

2016-03-01

We assessed the impact of personal CYP2D6 testing on physician assistant student competency in, and attitudes toward, pharmacogenetics (PGx). Buccal samples were genotyped for CYP2D6 polymorphisms. Results were discussed during a 3-h PGx workshop. PGx knowledge was assessed by pre- and post-tests. Focus groups assessed the impact of the workshop on attitudes toward the clinical utility of PGx. Both student knowledge of PGx, and its perceived clinical utility, increased immediately following the workshop. However, exposure to PGx on clinical rotations following the workshop seemed to influence student attitudes toward PGx utility. Personal CYP2D6 testing improves both knowledge and comfort with PGx. Continued exposure to PGx concepts is important for transfer of learning.

Quasi-static characterisation and impact testing of auxetic foam for sports safety applications

International Nuclear Information System (INIS)

Duncan, Olly; Alderson, Andrew; Foster, Leon; Senior, Terry; Allen, Tom

2016-01-01

This study compared low strain rate material properties and impact force attenuation of auxetic foam and the conventional open-cell polyurethane counterpart. This furthers our knowledge with regards to how best to apply these highly conformable and breathable auxetic foams to protective sports equipment. Cubes of auxetic foam measuring 150 × 150 × 150 mm were fabricated using a thermo–mechanical conversion process. Quasi-static compression confirmed the converted foam to be auxetic, prior to being sliced into 20 mm thick cuboid samples for further testing. Density, Poisson’s ratio and the stress–strain curve were all found to be dependent on the position of each cuboid from within the cube. Impact tests with a hemispherical drop hammer were performed for energies up to 6 J, on foams covered with a polypropylene sheet between 1 and 2 mm thick. Auxetic samples reduced peak force by ∼10 times in comparison to the conventional foam. This work has shown further potential for auxetic foam to be applied to protective equipment, while identifying that improved fabrication methods are required. (paper)

The Impact of Linking Distinct Achievement Test Scores on the Interpretation of Student Growth in Achievement

Science.gov (United States)

Airola, Denise Tobin

2011-01-01

Changes to state tests impact the ability of State Education Agencies (SEAs) to monitor change in performance over time. The purpose of this study was to evaluate the Standardized Performance Growth Index (PGIz), a proposed statistical model for measuring change in student and school performance, across transitions in tests. The PGIz is a…

Impacts Analyses Supporting the National Environmental Policy Act Environmental Assessment for the Resumption of Transient Testing Program

Energy Technology Data Exchange (ETDEWEB)

Annette L. Schafer; Lloyd C. Brown; David C. Carathers; Boyd D. Christensen; James J. Dahl; Mark L. Miller; Cathy Ottinger Farnum; Steven Peterson; A. Jeffrey Sondrup; Peter V. Subaiya; Daniel M. Wachs; Ruth F. Weiner

2013-11-01

Environmental and health impacts are presented for activities associated with transient testing of nuclear fuel and material using two candidate test reactors. Transient testing involves irradiation of nuclear fuel or materials for short time-periods under high neutron flux rates. The transient testing process includes transportation of nuclear fuel or materials inside a robust shipping cask to a hot cell, removal from the shipping cask, pre-irradiation examination of the nuclear materials, assembly of an experiment assembly, transportation of the experiment assembly to the test reactor, irradiation in the test reactor, transport back to the hot cell, and post-irradiation examination of the nuclear fuel or material. The potential for environmental or health consequences during the transportation, examination, and irradiation actions are assessed for normal operations, off-normal (accident) scenarios, and transportation. Impacts to the environment (air, soil, and groundwater), are assessed during each phase of the transient testing process. This report documents the evaluation of potential consequences to the general public. This document supports the Environmental Assessment (EA) required by the U.S. National Environmental Policy Act (NEPA) (42 USC Subsection 4321 et seq.).

General-purpose heat source: Research and development program, radioisotope thermoelectric generator/thin fragment impact test

International Nuclear Information System (INIS)

Reimus, M.A.H.; Hinckley, J.E.

1996-11-01

The general-purpose heat source provides power for space missions by transmitting the heat of 238 Pu decay to an array of thermoelectric elements in a radioisotope thermoelectric generator (RTG). Because the potential for a launch abort or return from orbit exists for any space mission, the heat source response to credible accident scenarios is being evaluated. This test was designed to provide information on the response of a loaded RTG to impact by a fragment similar to the type of fragment produced by breakup of the spacecraft propulsion module system. The results of this test indicated that impact by a thin aluminum fragment traveling at 306 m/s may result in significant damage to the converter housing, failure of one fueled clad, and release of a small quantity of fuel

The interpretation of Charpy impact test data using hyper-logistic fitting functions

International Nuclear Information System (INIS)

Helm, J.L.

1996-01-01

The hyperbolic tangent function is used almost exclusively for computer assisted curve fitting of Charpy impact test data. Unfortunately, there is no physical basis to justify the use of this function and it cannot be generalized to test data that exhibits asymmetry. Using simple physical arguments, a semi-empirical model is derived and identified as a special case of the so called hyper-logistic equation. Although one solution of this equation is the hyperbolic tangent, other more physically interpretable solutions are provided. From the mathematics of the family of functions derived from the hyper-logistic equation, several useful generalizations are made such that asymmetric and wavy Charpy data can be physically interpreted

Compaction comparison testing using a modified impact soil tester and nuclear density gauge

Energy Technology Data Exchange (ETDEWEB)

Erchul, R.A.

1999-07-01

The purpose of this paper is to compare test results of a modified Impact Soil Tester (IST) on compacted soil with data obtained from the same soil using a nuclear density gauge at the US Army Corp of Engineer's Buena Vista Flood Wall project in Buena Vista, Virginia. The tests were run during construction of the earth flood wall during the summer of 1996. This comparison testing demonstrated the credibility of the procedure developed for the IST as a compacting testing device. The comparison data was obtained on a variety of soils ranging from silty sands to clays. The Flood Wall comparison compaction data for 90% Standard Proctor shows that the results of the IST as modified are consistent with the nuclear density gauge 89% of the time for all types of soil tested. However, if the soils are more cohesive than the results are consistent with the nuclear density gauge 97% of the time. In addition these comparison tests are in general agreement with comparison compaction testing using the same testing techniques and methods of compacted backfill in utility trenches conducted earlier for the Public Works Department, Chesterfield County, Virginia.

Compaction comparison testing using a modified impact soil tester and nuclear density gauge

International Nuclear Information System (INIS)

Erchul, R.A.

1999-01-01

The purpose of this paper is to compare test results of a modified Impact Soil Tester (IST) on compacted soil with data obtained from the same soil using a nuclear density gauge at the US Army Corp of Engineer's Buena Vista Flood Wall project in Buena Vista, Virginia. The tests were run during construction of the earth flood wall during the summer of 1996. This comparison testing demonstrated the credibility of the procedure developed for the IST as a compacting testing device. The comparison data was obtained on a variety of soils ranging from silty sands to clays. The Flood Wall comparison compaction data for 90% Standard Proctor shows that the results of the IST as modified are consistent with the nuclear density gauge 89% of the time for all types of soil tested. However, if the soils are more cohesive than the results are consistent with the nuclear density gauge 97% of the time. In addition these comparison tests are in general agreement with comparison compaction testing using the same testing techniques and methods of compacted backfill in utility trenches conducted earlier for the Public Works Department, Chesterfield County, Virginia

Budget impact analysis of gene expression tests to aid therapy decisions for breast cancer patients in Germany.

Science.gov (United States)

Lux, M P; Nabieva, N; Hildebrandt, T; Rebscher, H; Kümmel, S; Blohmer, J-U; Schrauder, M G

2018-02-01

Many women with early-stage, hormone receptor-positive breast cancer may not benefit from adjuvant chemotherapy. Gene expression tests can reduce chemotherapy over- and undertreatment by providing prognostic information on the likelihood of recurrence and, with Oncotype DX, predictive information on chemotherapy benefit. These tests are currently not reimbursed by German healthcare payers. An analysis was conducted to evaluate the budget impact of gene expression tests in Germany. Costs of gene expression tests and medical and non-medical costs associated with treatment were assessed from healthcare payer and societal perspectives. Costs were estimated from data collected at a university hospital and were combined with decision impact data for Oncotype DX, MammaPrint, Prosigna and EndoPredict (EPclin). Changes in chemotherapy use and budget impact were evaluated over 1 year for 20,000 women. Chemotherapy was associated with substantial annual costs of EUR 19,003 and EUR 84,412 per therapy from the healthcare payer and societal perspective, respectively. Compared with standard care, only Oncotype DX was associated with cost savings to healthcare payers and society (EUR 5.9 million and EUR 253 million, respectively). Scenario analysis showed that both women at high clinical but low genomic risk and low clinical but high genomic risk were important contributors to costs. Oncotype DX was the only gene expression test that was estimated to reduce costs versus standard care in Germany. The reimbursement of Oncotype DX testing in standard clinical practice in Germany should be considered. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance of Waterless Concrete

Science.gov (United States)

Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

2010-01-01

The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.