Impact force from tipped cabinet

[junkforJG]

I'm trying to calculate an impact force from a tipped electronic cabinet.

I realize that are a lot of unknowns, but I'll replace those with some reasonable assumptions and see what my range of results will be.

My goal is to see the range of forces that PWB's inside the cabinet may have experienced.

Thanks,
JunkforJG

 

[junkforJG]

near enough

 

[3DDave]

One thing to note is that, in tipping, the corner of the base may have no impact while the top will have far greater impact.

 

[hydtools]

Maybe the corner will have higher velocity. Summing moments around the corner at the instant of impact would indicate lower force at the top.

Ted

 

[3DDave]

Does that include the rotational inertia? I mean, if I fell stiffly face down I would expect my face to hurt a lot more than my knees.

 

[LittleInch]

I realize that are a lot of unknowns

Well you're not wrong there - rather too many for any real figuring out I feel.

This cabinet of yours - did it tip over on one corner, fall from a height, fall on one corner, flat face
Did it fall onto a concrete surface? something else?
Did anything get deformed in the shell
Did anything get deformed inside the shell (seems like it)
What is the mounting of the bits inside, their mass, any attachment points?
Is the PWB fragile?

Far too many unknowns to get even close to a force and what then? How much force is OK and how much is in the grey zone?

Nope, just replace it all or test it all and visually inspect every last bit.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[zeusfaber]

Some of the attachment sheets of metal have bent as a result of the fall

but others didn't?

If you're trying to work out what this particular set of cards might have suffered with a view to working out whether they're fit for continued service, you might learn something useful by trying to work out what force it would have taken to mangle the weakest-looking bracket that actually survived.

A.

 

[itsmoked]

Rent a high speed camera and lay it on the floor (protected!) Put a ruler in view. Trip over the cabinet. The shutter timing against the ruler will tell you everything about the velocity and how fast it stops.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[chicopee]

To Hydetools "Is not F = m(v2-v1)/t sufficient to calculate impact force F? As IRSTUFF referenced, use t=.011secs" You are correct and as a matter US department of transportation back in the 70's?? did impact tests with vehicles against NJ barriers and this was the equation used, however, high speed cameras recorded the entire events and had come up with time for their calculations.