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Super Strong Metal Foam Discovered
MikeChino writes to tell us that a North Carolina State University researcher has discovered what appears to be the strongest metal foam yet, capable of compressing up to 80% of its original size under load and still retain the original shape. The hope is that this amazing material could be used in cars, body armor, or even buildings to absorb the shock from earthquakes. "Metal foam is exactly what you might think – a cellular structure made from metal with tiny pockets of space inside. What makes Rabiei’s metal foam better than others is that she’s been able to make the tiny pockets of space more uniform. And that apparently is what gives it the strength as well as elasticity it needs in order to compress as much as it does without deformation. Many tests are being performed in the laboratory to determine its strength, but so far Rabiei says that the spongy material has 'a much higher strength-to-density ratio than any metal foam that has ever been reported.' Calculations also predict that in car accidents, when two pieces of her composite metal foam are inserted 'behind the bumper of a car traveling at 28 mph, the impact would feel the same to passengers as an impact traveling at only 5 mph.'"
Maybe, maybe not. Elasticity is not the same thing as softness... steel is pretty elastic, but you don't necessarily want a face full of it in a car wreck. OTOH, landing in a bed of inelastic potato chips wouldn't be particularly painful (though it would be itchy).
Airbags and bumpers serve two entirely different purposes.
If this material lives up to the hype (unlikely), your next car will feature both items.
I'm curious to know more about the 28mph -> 5mph assertion. That stat was given to the media because it sounds impressive (grant guff), but how does it compare to the deceleration of a traditional auto bumper.
It sounds like a cool material, but the last thing we need is for something to make the idiot behind the wheel feel SAFER.
Oddly, the vehicles that make you FEEL safest are the most dangerous on the road -- SUVs. More people die in SUVs per passenger mile than any other kind of vehicle, and the reasons are simple. Their weight makes braking and handling problematic, their height makes handling problematic and rollovers easier, and they have no crumple zones. This stuff wouldn't make you feel safer, but it would make you BE safer.
George Carlin first talked about the metal spike, but he was joking. You're not supposed to take a comedian seriously, you know.
If I have a choice between hitting a pedestrian or a utility pole, I'll hit the pole. With the spike, one might not make that choice. You have to be crazy to think dangerous cars are safer; cars used to be a lot less safe then they are now; metal dashes, no ABS, no airbags. And then as now it was said "the most dangerous part of the car is the nut behind the wheel", and the people who said that were the ones who were against seat belts. With today's safer cars the death rate per passenger mile has plummeted.
Free Martian Whores!
This material reminds me of the lunar module's landing gear, made out of collapsible aluminum honeycomb. Look here for the word aluminum. Highly interesting.
The total impact energy (and momentum) of the bullet is constant regardless of vest type.
Lighter vests may not be able to spread the force of the impact over as large an area, so may be more likely to cause bruising.
In any case, the person firing the gun (assuming they're hand-holding the gun rather than having it fastened to something rigid) will need to absorb more energy/momentum when firing the gun than the target will when hit by the bullet. (Because the bullet is slowed slightly by air resistance.)
Thus, while you can knock someone down by shooting them (since as mentioned above the shooter can brace against the recoil) it's impossible to shoot someone with a standard slug from a hand-held weapon and make them fly through the air from the impact.
In 1976 I was driving a 1974 Gremlin at 50 mph, and had a head on collision with a quarter ton pickup truck that was doing 70. Back then they didn't even have padded dashes, let alone airbags; it was naked steel. I wasn't wearing a seat belt. I bent the steering wheel, and bent the dash where my shoulder hit it. The shoulder was permanently dislocated, but I had no organ damage (well, I may have suffered a concussion) or broken bones.
After the wreck you couldn't even tell what kind of car it was. I'll tell you though, it hurt like hell! My then-fiancee didn't fare nearly as well, her pelvis was broken in six places and she was in the hospital for a long time.
I've worn my seat belt ever since. You're in the most danger in the city at 30 mph where these new bumpers wouldn't help -- the deaths come from being t-boned.
Free Martian Whores!
You know what’s ignored and missing in this discussion?
The question of what the spheres are filled with!
Because they are certainly not “filled” with a vacuum.
But I think there got to be cool properties and applications, when you fill them with something else than air.
Any sufficiently advanced intelligence is indistinguishable from stupidity.
More like as a replacement for the ceramic ballistic inserts needed to obtain class iv ratings for body armor. This might be very useful for the military as the ceramic tiles generally only provide single shot protection as they shatter with the first round. That's where price comes in, the Dragon Skin body armor is already available for ~$5,000 for class iv rating.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
The problem is the use of the word 'absorb'.
You aren't going to absorb it in any useful amount, you have to spread it. The energy HAS to go somewhere.
People aren't really thrown back, they are knocked off balance because they weren't prepared for the energy imparted on them. If getting shot actually 'knocked you back' it would do the same to the person firing.
Body armor just helps spread the force across a larger area. Your body is pretty damn resilient, but when you rich the breaking point it just falls apart. Body armor tries to prevent it from reaching that breaking point by taking say (totally making numbers up here, I have no idea what the real values are) 2500 pounds of force in a 1/4" area and spreading it across say 10 inches of surface area, NOW you've got something that while it'll hurt like hell, won't actually kill you.
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Surely I'm not the only one that finds this statement,
"capable of compressing up to 80% of it's original size under load and still retain the original shape",
to be conflicted. Or this one,
"in order to compress as much as it does without deformation".
Come on, compression is a form of deformation.
So you're that asshole who stops a car length in front of the white line and doesn't trigger the pressure plate half the time. Thanks asshole.
But moderation will not do the job. If you want me to stop telling the truth even over the objections of liars, you're going to have to ban me from slashdot.
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