Shock Pulse -Equivalent Static load for FEA

[DonkeyDude]

Hi,

Shock testing (such as MIL-STD-810)normally involves applying an acceleration over a short time interval (example: 40g over 10 ms or something like that).

If you have access to basic FEA software, this can be applied as an equivalent static G load but it doesn't consider the dynamics.

Does anyone know how to make use of the shock amplification factor (assuming I can find natural frequencies of the structure using the same FEA software)to arrive at a reasonable estimate for the G load for a static analysis ??

Any simple example would be highly appreciated.

thank you,

DonkeyDude

 

[ColonelSanders83]

If you are worried about the dynamics then the only solution is to perform a dynamic analysis using the specified dynamic shock data.

I am also pretty certain much of the details you will need are classified (you should be carfull about your examples). Although it has been a while since I left that world.

 

[GregLocock]

"I am also pretty certain much of the details you will need are classified (you should be carfull about your examples). Although it has been a while since I left that world. "

Oh really.

DonkeyDude-you'll find a lot of threads on this in the acoustics/vibration forum. Have a read of them. I am 99% sure that Harris Handbook of vibration includes the very graph you need.

Cheers

Greg Locock

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

 

[zekeman]

Shock and Vibration Handbook,Harris and Crede,volume 1,chapter 8, McGraw-Hill,1961
Has the most complete discussion of your problem I've seen, but keep in mind that it assumes a single degree of freedom system undamped.