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Designing for impact

Designing for impact

Designing for impact

(OP)
Trying to design a mechanism to stop a moving weighted box that is on a trailer. Box weighs 2000kg and trailer is moving at speeds upto 20mph and will stop suddenly. Problem is there is nothing to stop the box flying into the front of the truck.  Looking to design a couple of latches to stop the box from hitting the truck when suddenly stopping.

What do i need to take into consideration?  Obviously I can work out the force of the impact on the box. How do i go about designing a latch?

Thanks

RE: Designing for impact

Make sure the latch's VM sttress is not higher than the Sy.

Tobalcane
"If you avoid failure, you also avoid success."
"Luck is where preparation meets opportunity"  

RE: Designing for impact

I think the latches he refers to are what the tiedowns hook to.

There are a lot of commercial latches available that can handle loads well in excess of this. A google of tiedown latches will give you some ideas.

But why reinvent the wheel?

RE: Designing for impact

It sounds as if you are designing a pulling sled; the way I take the question the mechanism that pulls the weight box forward is single-ended, that is, it constrains the box from moving rearward, but does not constrain against forward movement.

Some sleds I've seen simply use sloped ramps; any forward movement when the entire rig stops allows the weight box to rise and then fall back to the rearward constraint.  The better designs I've seen positively constrain and control the box movement both fore and aft.  

Acceleration forces on the moveable box are likely to be larger in the rearward direction than in the forward direction; the sled is pulled hard at the start but tends to be slowed by increasing friction rather than active braking, so a mechanism strong enough to accelerate the box forward should be adequately strong to also control the movement of the box during the stopping phase if the postioning mechanism wraps around the sled and constrains movement in both directions.

If this is indeed what you are trying to accomplish, post a sketch and we'll comment from there.

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