Shock Analysis using cosmosworks 1

[dimmane]

Hi, I´m trying to analize a 20g (where g is accleration due to gravity) 15ms (where ms is microseconds) shock with Cosmosworks 2006. Does anybody knows how to do it?.

thanks in advance,
Dinesh

 

[GBor]

I haven't used CosmosWorks, but I have used several comparable products. That is a pretty short shock. If you have non-linear materials, I'm not certain that the response you will get for strain-rate affects will be proper. You may need to go to Abaqus, LS-Dyna, or AMPS.

Otherwise, you need to run a dynamic analysis using acceleration vs. time as your input.

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group

 

[GregLocock]

I rather wonder if ms is milliseconds

Cheers

Greg Locock

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

 

[drbooshkit]

COSMOSWorks 2008 introduces linear and non-linear dynamic analysis. 2006/7 won't be able to model this behaviour ideally.

Brian

 

[mechengdude]

COSMOS works has a "gravity load" feature. I'm guessing since you are asking about COSMOS, thats the tool you have and using some other program may not be an option.

I would restrain the model and apply the appropriate gravity load. Posts relative to strain rate might be a concern as others have posted. You could add a factor of safety for conservatism to overcome that.

I asked a similar question in the past which was not specific to COSMOS but more if there is a standard design philosphy for calculating the shock loads per MIL-STD-810. I was suprised but it seemed that no one had a standard reference like used for dynamic testing (ie) the Miles equation, 3 sigma, cumlative damage etc.

 

[GBor]

mechengdude,

Must have missed the shock question. In the ship world, we used Mil-S-901D for shock guidance. There are some classified documents for specific coefficients, but a couple of packages offer Dynamic Design Analysis Method (DDAM) processors that are designed for surface and sub-surface ship shock. They have some built-in coefficients based on a declassified 1968 document.

I thought Mil-S-810 was more for vibration?

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
Magnitude The Finite Element Analysis Magazine for the Engineering Community

 

[mechengdude]

Yeah - there was nothing specific in the original post regarding shock although thats where MY mind headed when I read it. sorry for the confusion.

Regarding MIL-STD-810, it has quite a bit more than vibration. Of the top of my head it has shock, vibration, temperature, salt fog, dust, rain, etc. It or some derivation is used quite extensively in my experience for aircraft and mil vehicles.