Shock Physics
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A Space Debris Impact Test

A Space Debris Impact Test | Shock Physics | Scoop.it

Kevlar can fend off bullets traveling at hundreds of meters per second no problem, but the supertough synthetic fiber is no match for debris hurtling through outer space at several kilometers per second. In June, engineers at the Fraunhofer Institute for High-Speed Dynamics in Germany ran a space-debris simulation to test the fiber. Small meteoroids and other space flotsam can hit resupply vessels to the International Space Station, so the vessels have shields. Those shields are made up of an aluminum wall covering a layer of Kevlar and Nextel, a ceramic fiber. In the simulated impact, the engineers fired a 7.5-millimeter-diameter aluminum bullet from a specialized gun at a model shield. Traveling at about seven kilometers per second, the bullet punched a fist-sized hole through the Kevlar-Nextel fabric. Despite the damage, this shield did its job: dissipating the energy of the bullet and so protecting the inner walls

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Collision of High Speed Projectiles

This image, taken with the HPV-X, shows the instant at which a resin pellet, fired from a two-stage light gas gun at about 3 km/s, collides with the target at high speed. It allows verifying...
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Researchers use scientific guns to induce shock waves into explosive materials to study their performance, properties

Researchers use scientific guns to induce shock waves into explosive materials to study their performance, properties | Shock Physics | Scoop.it
As the U.S. Nuclear Deterrent ages, one essential factor in making sure that the weapons will continue to perform as designed is understanding the fundamental properties of the high explosives that are part of a nuclear weapons system.
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Putting iron to the stress test

Putting iron to the stress test | Shock Physics | Scoop.it

Using an ultrafast laser system, a group in Physical and Life Sciences at Lawrence Livermore National Laboratory have subjected iron to extremely rapid dynamic compression and have shown that the transition from one crystal structure to another can take place in less than 100 trillionths of a second after the compression begins.

If a material is squeezed hard enough, the way in which its atoms are arranged is often severely altered. In solids, pressure or stress may drive what are known as polymorphic transitions in which the crystal structure of the material changes from one form to another.

One of the best known of all such transitions is in iron and occurs at a typical stress of around 13 GPa (about 130 000 atmospheres). This transition has been very well studied over at least half a century since it was first inferred from shock wave measurements. However, the detailed nature of how it occurs is still not well understood. For example, how does it depend on the rate at which the stress is applied? How quickly can it take place and what are the characteristics of the material before and during the transition?

The team shows, qualitatively consistent with other recent reports, the stress at which the transition occurs is substantially higher (up to twice) than reported for typical shock wave experiments where the compression occurs more slowly. Furthermore, they showed that the "deviatoric stress"—a measure of the strength of the iron—is comparatively very large (up to 3 GPa) shortly before the transition begins. Team members analyzed their experimental data with a state-of-the-art theoretical method recently developed at LLNL.

"We hope this work will substantially improve our understanding of how polymorphic phase transitions take place under dynamic compression and inspire further interesting experiments and theoretical treatments," research member Jonathan Crowhurst said. "In particular, the time scale of the experiment is short enough to permit close comparison with the results of molecular dynamics simulations, which are emerging as the theoretical tool of choice for modeling this class of phenomena." Co-author Michael Armstrong also points out that "these far from equilibrium compression studies can also inform kinetic models of phase transitions in the limit of very high strain rates."

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Developing a spent fuel cask for air transport - Nuclear Engineering International

Developing a spent fuel cask for air transport - Nuclear Engineering International | Shock Physics | Scoop.it
The main driver of the requirements for air shipments of radioactive materials was the necessity to ship plutonium either for military programmes or as MOX fuel in civil programmes. The early editions of the IAEA's Regulations for the Safe...
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The Dragon's Tales: Experimentally Testing Martian Pit Crater Formation

The Dragon's Tales: Experimentally Testing Martian Pit Crater Formation | Shock Physics | Scoop.it

High-resolution images reveal that numerous pit craters exist on the surface of Mars. For some pit craters, the depth-to-diameter ratios are much greater than for ordinary craters. Such deep pit craters are generally considered to be the results of material drainage into a subsurface void space, which might be formed by a lava tube, dike injection, extensional fracturing, and dilational normal faulting. Morphological studies indicate that the formation of a pit crater might be triggered by the impact event, and followed by collapse of the ceiling. To test this hypothesis, we carried out laboratory experiments of impact cratering into brittle targets with variable roof thickness. In particlular, the effect of the target thickness on the crater formation is studied to understand the penetration process by an impact. For this purpose, we produced mortar targets with roof thickness of 1–6 cm, and a bulk density of 1550 kg/m3 by using a mixture of cement, water and sand (0.2 mm) in the ratio of 1: 1: 10, by weight. The compressive strength of the resulting targets is 3.2±0.9 MPa. A spherical nylon projectile (diameter 7 mm) is shot perpendicularly into the target surface at the nominal velocity of 1.2 km/s, using a two-stage light-gas gun. Craters are formed on the opposite side of the impact even when no target penetration occurs. Penetration of the target is achieved when craters on the opposite sides of the target connect with each other. In this case, the cross section of crater somehow attains a flat hourglass-like shape. We also find that the crater diameter on the opposite side is larger than that on the impact side, and more fragments are ejected from the crater on the opposite side than from the crater on the impact side. This result gives a qualitative explanation for the observation that the Martian deep pit craters lack a raised rim and have the ejecta deposit on their floor instead.

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Repeated self-healing now possible in composite materials

Repeated self-healing now possible in composite materials | Shock Physics | Scoop.it
(Phys.org) —Internal damage in fiber-reinforced composites, materials used in structures of modern airplanes and automobiles, is difficult to detect and nearly impossible to repair by conventional methods.
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Why Diamonds Are Good For Making New Materials

Why Diamonds Are Good For Making New Materials | Shock Physics | Scoop.it

Today, the U.S. Army Research Laboratory uses diamonds as part of a 10-year effort to investigate innovative approaches that enable revolutionary advances for the protection of soldiers and their equipment, particularly in dynamic environments, where extremely high pressure and high temperatures commonly exist.


An ARL research team lead by Dr. Jennifer Ciezak-Jenkins uses the diamond anvil cell technique, an experimental method, to subject small amounts of material to very high pressures when squeezed between two diamonds. Ciezak-Jenkins, a research scientist, leads the Diamond Anvil Cell research laboratory.

“It’s a brave new world in materials science,” Ciezak-Jenkins said, “in which the material properties can be tailored to meet the specific needs of the Army system or soldier in the field.”

Dr. John Beatty agrees. He manages ARL’s Materials in Extreme Dynamic Environments Collaborative Research Alliance. Under his watch, this alliance will build the capability to design revolutionary materials for protecting soldiers.

“No longer will we take materials ‘off the shelf’ to put into armor systems. Instead materials will become an integral part of the design process itself.”

ARL is conducting experiments with the diamond anvil cell that exert pressure at 300 gigapascals and above, “. . . which is in the range of pressures seen when a high-explosive material detonates, or when an armor system gets hit in the field,” explained Beatty.


The interest in high-pressure science grew out of the laboratory’s mission to study material behavior at conditions similar to those experienced during detonations.

 Over the past few years, the research has broadened to include a wider variety of materials because under extreme conditions material behavior does not always follow the conventional chemistry and physics rules learned in high school.

For example, nitrogen gas, the primary component of the Earth’s atmosphere, transforms into a structure very similar to diamond at 140 GPa and 4220 °F and it has been proposed that hydrogen transforms into a metal at conditions still being explored.

“At the bottom of the Marianna’s trench, the deepest part of the ocean, the pressure is about 0.1 GPa so we’re 3,000 times more than that. But it’s not enough to just expose materials to the pressure, we also have to understand how the material properties are changing in response to the extreme conditions,” Beatty said.

He said because the diamond anvil is transparent, ARL researchers can use several methods to examine the material while it is subjected to high pressure and/or high temperature such as laser-based spectroscopies and various forms of x-ray spectroscopy.

“The analysis from these experiments allows us to understand the changes occurring at the atomic level in response to these conditions. Armed with this information, we can then explore routes to stabilize these materials at lower pressures as well as techniques to synthesize the material without the pressure or temperature as is needed for larger scale production,” said Ciezak-Jenkins.

From this technique, researchers can understand a great deal about the material and how it may be beneficial to Army systems.

“We can use this information to validate models that are built-up from quantum mechanics to describe these materials. It’s a very important step in our quest to design materials to perform well when subjected to these extreme environments in the field,” said Beatty.

Diamond anvils are diamonds that have been polished flat by a laser-guided process.


Besides withstanding high pressure, they’re strong and hard, and they’re good electrical insulators and heat conductors. Diamond anvil cells have been used to simulate the high pressure in a variety of extreme environments, like the high pressures at the Earth’s core, or even the pressures that exist at inception on a nuclear blast.

Although it has advanced and evolved since, this experimental technique became popular in the late 1950s with researchers at the National Standards Board, now known as NIST, theNational Institute of Standards and Technology. Also growing during that time was a new field of study slowly embraced by industry and academia that would become the seed for future Army materiel: Materials Science.

It’s the scientific study of the properties and applications of materials and how those properties are determined by the material’s composition and structure, both macroscopic and microscopic.

Besides the diamond anvil cell, ARL uses another experimental apparatus, the Kolsky bar, to understand the behavior of material under high pressure and strain, or impact.

“In armor systems, protection materials are struck with a lot on energy in a small spot. Our enemies hope that that energy can basically go right through the armor system and damage the innards, and yes, that also means wounding or killing our soldiers inside. So we need to be able to examine materials when we load them up with energy real fast!”

“In a Kolsky bar, we send a high-stress pulse down a solid metal bar, then smash a sample between that bar and another one, and then examine the stress pulses that result. And those stress pulses tell us a lot about what happened to the material we were smashing,” said Beatty.


To improve that insight, ARL has changed how the Kolsky bar is used.

“Until recently, the systems we used were kind of limited into how fast they could deform or smash the materials we were looking at.” He said an ARL team led by Dr. Dan Casem has worked to modify the instrumentation used on the bars, which are typically as big around as the handle on a baseball bat. With the new optical instrumentation from ARL, the bars can now be made as thin as some human hairs. By making the bars smaller, “we can actually smash them in a way to get even higher deformation rates, at orders of magnitude greater than before, making the extreme environment during the test much more realistic.”

ARL’s work with Johns Hopkins University and Argonne National Lab is also utilizing similar high strain-rate tests with even more advanced diagnostics. They’re using the Department of Energy’s beam line to produce short pulse, high energy x-rays during these experiments.

These x-rays will allow us to take snapshots of many things going on inside the materials we are testing, such as phase changes, defect changes, etc.,” Beatty said. These experiments are needed to peer inside these materials during the experiments to validate the multiscale models that the ARL team is building from the atomic level up.

“We need these advanced techniques to both discover what we need to model, as well as to validate those models, to make sure they are real. Experiments matter and are critical to expanding our abilities to design materials,” said Beatty, “and the experimental capabilities of the Army’s Rodman Materials Laboratory at Aberdeen Proving Ground will be critical in achieving our goals.”

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Response of clamped sandwich beams subjected to high-velocity impact by sand slugs

The dynamic response of end-clamped sandwich and monolithic beams of equal areal mass subjected to loading via high-velocity slugs of dry and water-saturated sand is measured using a novel laboratory-based method. The sandwich beams comprise aluminium face sheets and an aluminium honeycomb core: the effect of sandwich core strength and beam thickness on the dynamic beam deflection is investigated by varying the orientation and height of the anisotropic aluminium honeycomb core material. High-speed imaging is used to measure the transient transverse deflection of the beams and to record the dynamic modes of deformation. The measurements show that sandwich beams with thick, strong cores are optimal and that these beams significantly outperform monolithic beams of equal mass. The water-saturated sand slugs cause significantly higher deflections compared to the dry sand slugs having the same mean slug velocity and we demonstrate that this enhanced deflection is due to the larger mass of the water-saturated slugs. Finally, we show that the impact of sand slugs is equivalent to the impact of a crushable foam projectile. The experiments using foam projectiles are significantly simpler to perform and thus represent a more convenient laboratory technique.

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rail gun hypervelocity weapon system

rail gun hypervelocity weapon system | Shock Physics | Scoop.it

@spinekim23 tweeted at 11:38 PM on Wed, Mar 26, 2014:
rail gun hypervelocity weapon system system http://t.co/BHLBArVqJD

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The Smallest Shock Wave


Focus: The Smallest Shock Wave


Observation and Control of Shock Waves in Individual Nanoplasmas

Daniel D. Hickstein, Franklin Dollar, Jim A. Gaffney, Mark E. Foord, George M. Petrov, Brett B. Palm, K. Ellen Keister, Jennifer L. Ellis, Chengyuan Ding, Stephen B. Libby, Jose L. Jimenez, Henry C. Kapteyn, Margaret M. Murnane, and Wei Xiong

Published March 18, 2014
B. Baxley/JILA

Shocking in a small way. A mixture of nitrogen gas and 100-nanometer salt crystals (light blue dots) enters from the left. The first laser pulse transforms a nanoparticle into a plasma, and the second drives a shock wave through the expanding plasma. The ions are propelled toward the detector by the washer-shaped electrodes. The detector records the positions of the ions, which correspond to their energies.

Laser pulses can produce an expanding shock wave in a tiny plasma of high-energy ions and electrons, according to work reported in Physical Review Letters. The researchers used a sequence of two laser pulses—one to vaporize a nanoparticle into a plasma and a second to generate the shock wave. Such “nanoplasmas” have been seen before, but this is the first time that researchers have observed a shock wave as it propagates through a nanoplasma. The discovery might ultimately lead to methods for producing ion beams for biomedical uses and could provide insights into other shock phenomena such as shock waves in supernovae.

High-energy particles in the mega-electron-volt range have been produced recently using only moderately intense lasers to generate nanoplasmas—tiny clouds of energetic ions and electrons. Nanoplasmas might ultimately allow researchers to produce high-energy particles without a particle accelerator, says Daniel Hickstein of the University of Colorado in Boulder. And since particles in a nanoplasma shock wave would have a narrow range of energies—a requirement for medical diagnostics and irradiation—creating such shocks could be a first step toward these medical uses.

Hickstein and his colleagues produced nanoplasma shock waves using a system that allows an unprecedented view of the rapidly expanding plasma. The researchers sent a beam of nanoparticles made from sodium chloride, potassium chloride, and other salts, into a vacuum chamber where they were illuminated with tightly focused, 40-femtosecond pulses of violet laser light. About one pulse in every 40 hit a nanoparticle and transformed it into a plasma of ions and electrons. After the plasma had time to expand, the positive ions were drawn up through the centers of two washer-shaped electrodes above the beam and guided to a detector, which measured the particles’ energies.

The energies of the ions ejected from the plasma were not very high compared with other nanoplasma techniques that use smaller nanoparticles and more intense lasers. But the system allowed the team to record the complete energy spectrum of each nanoplasma individually, rather than averaging many together. These energy spectra showed that the intense laser pulses produced shock waves in some of the nanoplasmas, identified by ions clustered into a narrow energy band. The team found that by using a second laser pulse of near infrared light to heat the nanoplasma abruptly, they could create a much stronger shock wave.

But these strong shocks only appeared if the time delay between the first and second pulses was at least 7 picoseconds—long enough for the plasma to expand (increasing its ability to absorb laser light) before the second pulse arrived. According to the team’s calculations, the shock wave is formed as the second pulse is absorbed in a shell of the material, sending a pressure wave into the middle of the plasma that bounces back as an outward-moving shock composed of ions with essentially identical energies.

“Experimentalists have been looking for these shock waves for the past decade, but they have not found them,” says Hickstein. In 2003 a team proposed that nanoplasma shock waves could lead to many interesting effects, including a method to achieve nuclear fusion between ions in a nanoplasma [1]. Hickstein says his team succeeded because they used 100-nanometer-sized particles, 20 times larger than previous experiments. “The larger particle size lets us probe a single nanoparticle at a time,” which he says is crucial for observing the shock wave. With many nanoplasmas averaged together, as in other experiments, the shock would be blurred by the variability among different nanoplasmas.

“The control and imaging of the dynamics of a single nanoplasma is a critical experimental achievement,” says Luis Silva, a plasma physicist at the Instituto Superior Técnico in Lisbon, Portugal. “It opens several avenues for exploration—on the dynamics of these nanoplasmas themselves and on the dynamics of spherical shock waves present in many laboratory and astrophysical phenomena.”

Thomas Fennel of the University of Rostock in Germany cautions that a shock wave may not be the only explanation for the data. “Future theory studies that resolve the different atomic species will show if the interpretation is correct,” he says.

Hickstein stresses that the current results remain a long way from what is required for potential medical uses, and in any event, much fundamental work needs to be done first. “In the short term, we need to gain a better understanding of how exploding nanoplasmas behave and how we can control them,” Hickstein says.

esearchers create shock waves in a nanosized ball of plasma.

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WSTF Hypervelocity Gun Lab - YouTube

WSTF Hypervelocity Gun Lab (J'aime une vidéo @YouTube : "WSTF Hypervelocity Gun Lab" à l'adresse http://t.co/VHBgw1r2UF.)
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[1403.3230] Numerical solution of the Boltzmann equation for the shock wave in a gas mixture

Numerical solution of the Boltzmann equation for the shock wave in a gas mixture. (arXiv:1403.3230v1 ... http://t.co/NJIl6rF6jV #physics
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Determining structural evolution under pressure

Determining structural evolution under pressure | Shock Physics | Scoop.it
The study of material properties under the conditions of extreme high pressures and strain rates is very important for understanding meteor, asteroid or comet impacts, as well as in hyper velocity impact engineering and inertial confinement fusion capsules. In a recent study, a team scientists report an important finding that can be used to determine the evolution of structures under high pressure and strain rates.
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Joint Actinide Shock Physics Experimental Research - JASPER

Commonly known as JASPER the Joint Actinide Shock Physics Experimental Research facility is a two stage light gas gun used to study the behavior of plutonium and other materials under high...
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Laser-Induced Projectile Impact Test Uses Microbullets to Demonstrate the ... - Azom.com

Laser-Induced Projectile Impact Test Uses Microbullets to Demonstrate the ... - Azom.com | Shock Physics | Scoop.it
Scientists at Rice University have used microbullets to determine the strength of the material. The research team believe that this technique could be used to measure the strength of a wide range of materials.
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Laser researchers revolutionize aviation industry

Laser researchers revolutionize aviation industry | Shock Physics | Scoop.it
(Phys.org) —Most people don't realize it, but the airplane they are flying on may be stronger and safer thanks to a pair of former Lawrence Livermore National Laboratory researchers who developed and commercialized an innovative but relatively obscure technology.
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High-speed fiber grating sensors for measuring detonation - SPIE Newsroom

High-speed fiber grating sensors for measuring detonation - SPIE Newsroom | Shock Physics | Scoop.it
High-speed fiber grating sensors for measuring detonation SPIE Newsroom The ability to continuously identify the position, velocity, local pressure, and temperature of energetic materials during the early stages of detonation and the transition to...
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Physicists discover new type of particle using Large Hadron Collider

Physicists discover new type of particle using Large Hadron Collider | Shock Physics | Scoop.it
Syracuse, N.Y. (UPI) Apr 15, 2013
A new and exotic atomic particle - one that doesn't mesh with traditional particle physics models - has been discovered by researchers at Syracuse University.
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Navy Plans to Test Fire Railgun at Sea in 2016

Navy Plans to Test Fire Railgun at Sea in 2016 | Shock Physics | Scoop.it

The Navy will fire its electromagnetic railgun from a joint high speed vessel in 2016 as part of a broader effort to develop the long-range, high-energy weapon, service officials said.

The weapon will be placed on display this summer aboard the USNS Millinocket, a Navy JHSV which entered service in March. Following the display, the railgun will then be demonstrated on the same ship in 2016.

"We want to get this out on a ship and understand what lessons there are to learn," said Adm. Bryant Fuller, Chief Navy Engineer.

This move to test the weapon at sea, on a ship, marks the latest phase in the ongoing development of a new high-tech weapons system.

"We're talking about a projectile we're going to send well over 100 miles. We're talking about a projectile that can go over Mach 7. We're talking about a projectile that can go well into the atmosphere. We're talking about a gun that is going to shoot a projectile that is about one-one hundredth of the cost of an existing missile system today," said Adm. Matthew Klunder, Chief of Naval Research.

The railgun uses electrical energy to create a magnetic field and propel a 23-pound kinetic energy projectile at Mach 7.5 toward a wide range of targets, such as enemy vehicles, or cruise and ballistic missiles.

Due to its ability to reach speeds of up to 5,600 miles per hour, the hypervelocity projectile is engineered as a kinetic energy warhead, meaning no explosives are necessary, said Fuller and Klunder. 

"You have 23 pounds going Mach 7, you don't necessarily need an explosive detonation to create damage," Fuller said.

However, different combinations of high-tech materials called energetics could be used to increase lethality or impact.

"We've done a number of models, and [the HVP warhead] gives us the ability to knock anything out of the air. We did lethality models on every single mission we have in the Marine Corps and the Navy. This could damage and be lethal in every occasion," Klunder added.

Although it has the ability to intercept cruise missiles, the 23-pound hypervelocity projectile can be stored in large numbers on ships. Unlike other larger missile systems designed for similar missions, the hypervelocity projectile costs only $25,000 per round. 



The railgun can draw its power from an onboard electrical system or large battery, Fuller said. The system consists of five parts, including a launcher, energy storage system, a pulse-forming network, hypervelocity projectile and gun mount, he said.

"In 2016, we are going to bring all these pieces together on a ship and start learning what we can learn in a marine environment," said Fuller.

The gun is configured for single shots; however, officials hope the weapon will fire up to 10 rounds per minute, Fuller said. Firing multiple rounds per minute is part of the weapon system's ongoing phase two development.

BAE Systems was awarded a phase-two contract from the Navy last summer for the development of the railgun, but there are other vendors working on different aspects of the system.

Raytheon, General Atomics and BAE were all awarded development deals in 2012 from the Navy to develop a pulse-power system for launching projectiles in rapid succession -- to achieve a firing rate of six to 10 rounds per minute, said Peter Vietti, spokesman for the Office of Naval Research.

A number of different firing and guidance technologies are still being considered for the weapon, but Navy officials said the hyper-velocity projectile can use GPS guidance toward targets.

The electromagnetic railgun generates force equivalent to 32 megajoules. Fuller explained that one megajoule is equal to one ton traveling at 100 miles per hour.

"Like a freight train going through the wall at 100 miles per hour," Fuller added.

Fuller also said the software for the system is built with what he called open architecture, meaning the electromagnetic railgun could easily be configured for other ships in the future.

The upcoming demonstration on JHSV is the latest in a series of developmental initiatives with the railgun. The weapon has been tested and developed at the Naval Surface Warfare Center in Dahlgren, Va. Last December, the railgun fired eight shots at White Sands Missile Range, N.M., Klunder said.

Following these tests, Defense Department officials have considered additional applications for the railgun across the services.

In particular, if the high-speed kinetic energy interceptor can reach distances of 100 miles and succeed in destroying large missiles, then it could be used against missile threats outside or above the Earth's atmosphere. Therefore, it's possible the railgun could be useful for ballistic missile defense because experts explain the Earth's atmosphere extends roughly 60 miles above the surface.

Klunder said the weapon could have a huge effect as a deterrent.

"Now you've a hugely capable multi-mission gun that has a huge affordability component. I think it will give our adversaries a moment of pause to say ‘I do not even want to engage a Navy ship because I'm going to lose,' " Klunder said.

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CFD Predicting Impact Loading of a Hydrodynamic Wave on a Submarine

CFD Predicting Impact Loading of a Hydrodynamic Wave on a Submarine | Shock Physics | Scoop.it
CFD Predicting Impact Loading of a Hydrodynamic Wave on a Submarine
ENGINEERING.com
Within each computational cell the VOF, pressure, velocity and gravitational force acting on the fluid is calculated.
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New Super-Strong Ceramic Material Inspired By Mother-Of-Pearl Created

New Super-Strong Ceramic Material Inspired By Mother-Of-Pearl Created | Shock Physics | Scoop.it
A new super-strong ceramic material — inspired by the mother-of-pearl created by the single-shelled marine mollusks known as abalones — has been created by a team of researchers led by the Laboratoire de Synthèse et Fonctionnalisation des Céramiques.This new “artificial mother-of-pearl” is considerably less prone to fracture than conventional ceramics, as well as being nearly 10 times stronger. The material retains its properties even when exposed to rather high temperatures — up to at least 600°C.
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Spectacular detonation of recovered WWII sea mine | VIDEO

Sea mine was detonated by the Dutch EOD. The Explosive Ordnance Disposal detonated it on Wednesday leaving a big crater in the sand. (this is the sea mine i mistook for space junk. Of course, had I known it was a bomb, I wouldn't have hammered on...
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'Shrapnel' risk to Moon missions

'Shrapnel' risk to Moon missions | Shock Physics | Scoop.it

The "shrapnel" generated by small space rocks that periodically hit the Moon may pose a larger risk to lunar missions than was previously believed.

A number of countries and private consortia have stated their plans to send robotic and crewed missions to the lunar surface in the coming decades.

A relatively small impact on the Moon last year hurled hundreds of pieces of rocky debris out of the crater.

Many were travelling at the speed of a shotgun blast.

The meteoroid strike sprayed small rocks up to 30km from the initial impact site, said Professor Mark Robinson, from Arizona State University.

He presented his analysis at the 45th Lunar and Planetary Science Conference (LPSC) in The Woodlands, Texas.

Along with colleagues, he used the LROC imaging instrument aboard Nasa's Lunar Reconnaissance Orbiter spacecraft to follow up on observations from 17 March 2013 of an apparent collision on the Moon's surface.

The orbiter took pictures of the area that corresponded to co-ordinates for the impact flash.

Prof Robinson and his team found a fresh 18m-wide crater, punched by a 0.3-1.3m-wide space rock. The crater is surrounded by typical "ejecta" deposits - the continuous blanket of rock and soil heaved out when the meteoroid thumped into the lunar surface.

However, they also saw 248 small "splotches" extending up to 30km from the primary crater. This was further than the typical extent for continuous ejecta deposits from a lunar crater.

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Cask Crash Test - 1978 - YouTube

Test of shipping containers for spent nuclear fuel by Sandia Corp. Impact tests (trucks ram concrete wall at different speeds; diesel locomotive broadsides t... (Nuclear fuel cask impact tests, 1970s.
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