Shock limits for electronic components

[alamzeb]

hi,

Just had a small question, I am hoping that someone here has come across this. Is there some kind of a shock / vibration frequency limit for electronics? Can we find a value like that in a spec for a device/component? And also if its a generic kind of value for all electronics (e.g. above 20g's and 1000Hz vibration frequency component x will fail) or a place where we can find such numbers?

I am actually looking at putting togather a spec for RFID tags on drill pipes which would withstand high freq. shocks. If anyone has any ideas on how to test this scenario it would be great.

Thanks,

 

[IRstuff]

You need to talk to your mechanical engineers. Electronics can and are being fired in cannons, so inherently the limits are quite high. However, I was told that someone's first attempt at a cannon-fired guidance system wound up with a small pile of rubble from the first shot, so your mechanical designers do need to do serious design work if the shock levels are truly high.

But first, you need to determine the level of shock you need to survive, then design around that. Most military electronics can easily survive 20 g and operate afterwards (MIL-STD-810F). Critical electronics on military ships are designed to survive, and possible operate through, shocks above 300 g's (MIL-S-901D)

TTFN

FAQ731-376

 

[alamzeb]

Thanks for the info. So from what I gather it seems 300g's is a big number (possibly like a high end limit) but for something designed to survive 300g's, do you know what kinda of a duration of shock do they expect.

After a little more discussion with our engineers I found that definition of a shock can also be taken different ways for calculating a damage curve of a component. number cylces, g's, duration all matter. Do you know if the MIL-S-901D accounts for the other variables also?

Thanks,

 

[IRstuff]

Again, the shock environment is something that you need to get from your customer(s), as with the shock durations. These are all extremely application specific. What is correct and applicable for a military system may have zero bearing on your application.

MIL-S-901D is intended for a single shock, or a few shocks, environment. It's not expected that a ship will be under continual attack for very long, without either winning or getting sunk.

TTFN

FAQ731-376

 

[GregLocock]

As an example the radar proximity sensor in an AA shell was designed for several thousand g, from memory, and given that this was in WW2 that would have been with thermionic valves.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[IRstuff]

Probably so, but it was also probably a specially constructed tube, one with strengthened structures.

TTFN

FAQ731-376

 

[tomirvine]

Refer to:

Dave S. Steinberg, Vibration Analysis for Electronic Equipment

Tom Irvine

http://www.vibrationdata.com

 

[spongebob007]

Generally speaking, commercial off the shelf (COTS) electronics components are able to survive shocks of 20Gs or less. But you really need to refer to manufacturers data if it exists.