Friday, August 17, 2012

Soft but hard armor

It seems the material turns hard in the instant it's struck, and distributes the force of the impact over a larger area. I've heard of such things for a while, and it was imagined in the famous SF book Ringworld from 1970, if I recall right.

This article says:
These materials, also know generically as “rate-dependent materials,” work by having their molecules freeze in place when struck hard, but are pliant when moved gently — just like water, which is a rate-dependent material of a sort. If you lower yourself into a bath there is little resistance. But slap the water hard with the flat of your hand and it will leave your palm stinging.

I think the latter is just platypus, though. With water it's just enertia, water is dense and can't get out of the way fast, so it feels hard to hit fast. (A speedboater said he'd rather fall of his motorcycle than his boat.)


Roger B. said...

I immediately thought of clothing for riding motorcycles, and it's already been done, aimed at scooter riders.

It would think that it would be especially good for gloves and boots, protecting lots of small fragile bones yet allowing movement.

I expect that it would need to be protected by another layer against gravel rash, but it sounds like just the stuff.

It would also be useful for a camera case that takes up little room yet will protect against impact; just the thing for a small camera that gets taken everywhere.

Dave said...

see this link

Its a non-Newtonian liquid that appears liquid when moved slowly but when struck it goes solid eg like a bowl of thick custard.

Eolake Stobblehouse said...

Yes, it's being used on cell phone cases already, apparently successfully. It surprises me a little, because while the corner might not be bent, the whole phone will still get an awful shock if dropped upon something hard. But I guess they don't really have much in the way of movable parts.

Roger B. said...

I suppose that what's needed is two things; something that spreads the impact over as wide an area as possible, and something that reduces the peak impact by deforming and transmitting it over a longer time.

An example would be a crash helmet.