MIL-STD Test Method 516.6 – Shock

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Video Transcript: Episode 84 – “MIL-STD Test Method 516.6 Shock”

Hi, Jim Shaw here from Crystal Group. Today we’re diving down a little bit deeper into MIL-STD-810 and we’re talking about method 516 which is shock. And shock, this is kind of an interesting procedure inside method 810 because there are eight different shock test that you can actually specify in this particular method. So what are you actually testing for? When you see a shock pulse being applied to a piece of equipment you’re looking for distortion, you’re looking for damage to solder joints, electrical circuits. You’re looking for material to be fractured or damaged in some way, connector failures, things like that.

So there’s a lot of different things that you’re looking for. In the vetronics and avionics area that we work in really we’re most interested in procedure one which is operational shock and procedure five which is crash safety. So of those eight different procedures, you can have catapult arrest, you can have transit drop, there’s a bunch of different tests that you can go through. But of those eight we’re mostly concerned with those two, procedure one and procedure five.

And these shock values are anywhere from 20G’s to say 40G’s. They can go as high as 75. But normally we see them in a 20-40G range. And the duration for those shock pulses are generally in the 10-23 millisecond response for the shock pulse. So the thing about shock is, the longer the duration and higher the pulse, the more damage that you can do. So a 40G shock pulse that’s 20 milliseconds is more damaging than say a 20G shock pulse for 10 milliseconds. So that’s kind of just a little bit of background for you.

What we normally do in this industry is a half-sine or a sawtooth shock pulse wave. And so those are generally the two that we see most frequently as specified by our customers. These are pulses that are applied two times per axis and then in each direction. So that’s eighteen different shock pulses that you would test your unit for while it’s sitting on the vibration table. And these are generally done on a vibration table. You can get some testing where you do hammer blow or even barge test.

That’s actually a different spec though that’s not MIL-STD-810 that’s MIL-S-901. So generally for MIL-STD-810 you’ll see this kind of testing done on a vibration table that has the shock test capabilities. And so again, it’s a fairly quick test to do. We generally do a vibration test and then before we move the axis we’ll actually hit the unit with the 40G shock pulse which is generally crash safety and then operational testing is usually the 20G test.

At Crystal Group we’ll do kind of a worst case here we’ll actually run the operational shock test at 40G’s so we try to do that little extra bit there to make sure that we’ve got a robust product by giving it a little extra testing. So that’s essentially how we do it here at Crystal Group. I hope that was useful, have a good day.

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