Materials From Tough-as-Nails Crustacean Could Inspire Better Body Armor 144
carmendrahl writes "The peacock mantis shrimp, a crustacean which is neither a mantis nor a shrimp, has hammer-like clubs for smashing the shells of its prey. They're so strong that regular glass aquariums can't hold them. But what's interested researchers for some time is how the clubs stand up to all that stress. Now, a team has figured out why: the mantis shrimp club's molecular structure is set up to resist fractures. That discovery could lead to stronger and lighter car frames or body armor."
Stronger, lighter cars? (Score:5, Informative)
No. We have already passed the point on the strength axis at which the car survives but the occupants die of internal injuries. For cars, what you need is energy absorption to decelerate the car's contents gradually. That means a body that will crumple.
Body armor, perhaps. Here, the total energy of a typical round is not lethal if it can be spread over a large area of the body. This can be facilitated by stiff materials backed by some padding.
Comment removed (Score:5, Informative)
What we've got (Score:5, Informative)
Just to outline what the standard gear can do as of fairly recently; I'm out, but I wore it in 2010.
The kevlar lining in the vest, by itself, is rated to stop 9mm pistol rounds.
The main chest and back ESAPI plates are rated to stop a NATO 7.62x51 round. (The AK commonly fires the lighter 7.62x39 round.)
The armor is bulky as hell. The full assemblage, helmet, shoulder protectors, front and back plates, side plates, etc., is heavy and greatly restricts movement. I found it very difficult, with everything on, to man a gun and drop down to check radios. (I've also never found a decent pair of gloves.) I stopped wearing the neck protection and shoulder protection while driving because I couldn't easily turn my head.
The problem of being trapped is partially addressed through the quick-release mechanism; there is a strap you pull that will simply make your armor fall off. Of course, there's a fairly elaborate system of cables wound throughout the armor, and the armor itself is more annoying to put on.
My feelings are that we're well past the point where the increased likelihood of getting shot while stumbling around is worse than the benefits of not getting hurt by shrapnel. I'm considering a common combined IED and small arms attack in which the convoy is successfully stopped, and they have to kick out dismounts to respond. In that scenario, getting in and out of vehicles is very dangerous (especially some MRAPs where you have to basically go out ass-first) and performing tricky tasks like hooking up tow bars and tow cables.
The next biggest problem is it's hard to allow air flow. The armor tries, and they recently came out (thank god) with a lighter shirt to wear underneath it instead of the regular ACU top. That was a huge improvement, but it's fundamentally hard to put yourself inside a ceramic box and not cook.
Except for shoulders (and no one wants to wear the damned shoulder armor) it doesn't protect joints. The neck protection further restricts mobility.
Wearing it, overall, I felt like a damned turtle. Other people I saw didn't seem to be doing much better.
Re:Stronger, lighter cars? (Score:5, Informative)
Ok time for a mechanical engineer to step in here. There is some confusion between stiffness and strength. These are two different properties of the material.
Stiffness is the ability of the material to resist deflection. Think of identically shaped tube held fixed in one end made from different materials. Now put a force on the other end and assume it is small enough so you don't bend the tube permanently. All aluminum tubes will deflect about 3 times that of all steel tubes. It doesn't matter what kind of aluminum or steel. This is due to a property called Modulus of elasticity.
Now when we talk strength of metals we have two types. The first is yield strength. In the above example this would tell you what load the tube could take before it bends to the point when you remove the load it doesn't return to its original shape. The next is ultimate strength. This is the load when the tune actually breaks.
These strengths vary widely for metals with some aluminums stronger than steels and the other way around.
The next thing is density. Aluminum is 1/3 the density of steel. But you need more if it to make a stiff structure.
So what does this mean for impacts in cars? You want a material that is stiff for its weight so that it can absorb the energy as it deflects but also strong so that it doesn't break as it deflects. Ideally you would want your car to crush like modern cars do to absorb the impact then return to their original shape so there is no damage.