When a modern car gets into a collision, the vehicle's crumple zone does it's job of absorbing energy and protecting the passengers, and then looks like a mess. Bent parts need to be removed and either repaired or replaced.

If major parts of the car were assembled using rare earth element magnets, instead of welds, rivets, or bolts, the energy of the collision could go into the act of pulling these magnets apart, and into flinging bits and pieces away from the passenger cabin.

After the collision, the bits and pieces (which would mostly be intact, just not attached to the car or one another) could then be reassembled.

Obviously, due caution should be observed during reassembly, since magnets this strong could easily do some damage when being put together -- to themselves, to the components they're being stuck to, and to the people assembling them.
-- goldbb, Aug 11 2010

'clumping structural models' Clumping_20structural_20models
Same notion, but suggested for virtual assembly rather than assembly in meatspace. [LoriZ, Aug 17 2010]

Magnificently impractical and costly. [+]
-- gisho, Aug 11 2010


There was some talk of "smart fasteners" a few years ago. They looked like normal fastener, but had electronics that controlled magnet-actuated latches inside. Those would be much stronger than magnets, as they have solid fastenings, not just magnets. In an emergency, they could be told to turn loose.

I'd want to see some serious design of the parts this idea describes. Flat mating surfaces would slide around, but poorly-designed notches would prevent free separation in a collision.

Assembly would require laying the parts on some plastic shims that could all be pulled out together. Disassembly would require shims that could be hammered in between the parts--magnets hold tightest whilst closest together, so getting a shim started would be a bugger.
-- baconbrain, Aug 12 2010


No magnet would be strong enough to do the job.
-- RayfordSteele, Aug 12 2010


//After the collision, the bits and pieces ...could then be reassembled.//

With magnets they would do this on their own, assembling into a pile of debris ready for removal.
-- ldischler, Aug 12 2010


Vehicle crumple zones are designed to absorb energy when the metal yields as they crumple. Ideally, the energy is absorbed at a constant rate with yield, or at an increasing rate (like a spring, but with no, or minimal recoil). These magnets would absorb a small ammount of energy as they were pulled apart, but the effective "stroke" length is small. Once the magnets are outside the attraction zone, there is no resistance and, well, you're f^cked.
-- Custardguts, Aug 12 2010


Brilliant! Some might not have heard of a Demolition Derby; but in some parts of the country they are quite popular. The premise is that a lot of cars are in a coliseum sized arena, and they try hard to bash all of their competitors to itsy bits. The winner is the last one who can still drive around under his own power. Using [goldbb]'s marvelous invention, you could crash your Chrysler into a Fiat, and once the parts from both cars begin to coalesce again, you could well be driving a Cry-a-Lot. Then this car you could crash into a Volvo and end up with a... hey, wait a minute, get that Volvo out of the Demolition Derby before somebody doesn't get hurt!

Bun [+].
-- Grogster, Aug 12 2010


make it pretty easy to get parts for your car: just visit the nearest parking lot with an electromagnet to temporarily depolarise the permanent magnets. [+] yeah I could use that.

As a bonus your car would pick up spare change as it rolled along.
-- FlyingToaster, Aug 12 2010


//the collision would not be between two huge heavy vehicles full of people, but between thousands of small low-mass discrete components//

That would pass through each other harmlessly and reassemble on the other side. Good as new, except maybe the engines. And the drivers.
-- ldischler, Aug 12 2010


Custardguts, if the magnets are strong enough to hold the car together for normal use, it would take a lot of energy to separate them.

I will admit that the energy is absorbed at a decreasing rate, not constant or increasing, but how much of a problem is that?
-- goldbb, Aug 15 2010


I would personally prefer that my automobile convert a maximal quantity of momentum into other forms of energy over a maximal amount of time thus minimizing the extent to which my tissues need to do so. For this purpose the structural components of the car mus remain attached to each other in an accident. They also need to remain structurally attached to my seat belt, seat, and airbags and prevent intrusion into the space containing my organs.
-- WcW, Aug 17 2010



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