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A study led by Assistant Professor Darren Chian Siau Chen from the Department of Civil and Environmental Engineering at the National University of Singapore's Faculty of Engineering has found that when a projectile is fired at a sand block at high speed, it absorbs more than 85 per cent of the energy exerted against it. This ability to resist the impact increases with the speed of the projectile, even at high velocities.
While sand has been used traditionally for military fortification, very little is known about the unique energy absorption capability of the material. In a recent study, a team of researchers from the National University of Singapore's (NUS) Faculty of Engineering found that sand can absorb more than 85 per cent of the energy exerted against it, and its ability to resist the impact increases with the speed of the projectile, even at high velocities. In contrast, steel plates have poorer energy absorption capacity against high speed projectiles. This novel finding suggests that sand can potentially be used as a cheaper, lighter and more environmentally friendly alternative to enhance protection of critical infrastructure as well as armour systems.
[Editor's note: We've previously discussed an impending shortage of sand..]
(Score: 2) by Runaway1956 on Tuesday December 13 2016, @03:06AM
"Absorbing" energy? I think they're looking at this whole thing from the wrong angle. Energy from a bullet isn't exactly "absorbed" by either a body, or by sand. Instead, the energy is dissipated - redistributed into many different directions. Sand, like a meat body, has give to it, allowing that energy to be redirected in many different directions. Unlike a meat bag, sand isn't composed of cells full of water that rupture during the process.
There are some fascinating videos on Youtube, of slow motion impacts of bullets. You can see the energy spread from a point, out into a cone. Depending on whether the bullet fragments, there may be multiple paths, with multiple cones.
(Score: 2) by Scruffy Beard 2 on Tuesday December 13 2016, @05:34AM
Could be bad translation.
(Score: 1) by Tara Li on Tuesday December 13 2016, @03:58PM
You've also got fracturing of sand grains against each other soaking up a lot of the energy. Even just the fact that it can re-arrange itself absorbs a lot of the energy. I'm not sure sand is the absolute best at this kind of thing - maybe something more elastic?
(Score: 2) by Taibhsear on Tuesday December 13 2016, @04:41PM
Exactly. I'm curious how the sand's absorption compares to non-newtonian fluids that they are testing for new body armors.