Nastran: how to obtain 1-sigma stresses for SOL 111 1

[jo1234]

How can I obtain from a sol 111, random vibration analysis with input PSD curve, the 1-sigma, 2 sigma and 3-sigma stresses in MSC/Nastran?

Thank you

 

[mae1778]

If you have Patran, you can just use the MSC.Random tool. Run sol 111 with 1G and post process the PSD with MSC.Random.

 

[jo1234]

Thank you mae1778. That helps a bit, however, we dont use Patran, so is there any other way? arethe 1-sigma stresses contained in the fo6 or op2 output?

Thanks

 

[mae1778]

I've never done this myself, as I use the MSC.Random tool, but according to nas102_wk10.pdf (not sure about the copy-write rules, otherwise I would post it for you) on the MSC support page, you would add:

Random = n (same number as the RLOAD2 table ID)

to your subcase control and reference the PSD in your RLOAD2 card.

For RMS Values, you would add something like:
XYPLOT ACCEL PSDF / NodeID(direction)

Hope this helps. I might try it out myself.