Very long solution times for random vibration analysis

When trying to simplify your model, did you consider symmetry?  Even using 1/2 symmetry could cut your solution time in 1/4.

Also, if you have a lot of sheet metal, and it's all joined together, you can approximate several parts by one conglomerate part.  Sometimes this will reduce the number of DOF required because you can create simplified continuous geometry rather than have disjointed parts with small edges, faces, etc.

Sometimes you can justify creating a shell-type model where a solid model was used before, e.g. if you're not terribly concerned with the stresses in that part, but you want to capture the flavor of its interaction with the other parts, you can turn a lump-shaped part into a flat piece of thick sheet metal.  If it's sheet metal, SW treats it automatically as shell elements (as long as it is wider than it is thick, but you can force that if you have to) and that saves you a good amount of solution time.

Perhaps you could exclude many parts from the analysis completely.  Sometimes we think things really matter, when in the end, they just add complexity to the solver's calculations.

Best of luck (and skill),

David Fletcher

I run a good many random vibration problems here at work -- what all are you interested in?  For example, I may run a study with about 150k DOF, but I'm only interested in the stresses produced.  I can cut the solution time down from about 40 minutes to less than 5 if I make sure that only PSD stresses are selected under result options.  Also, even though I run studies from 5-500 Hz with 50 frequency points, I always modify the result options to only save data for Solution Steps - Set1: Start: 1, End: 1000, and Increment: 1000.  Even though my study may have 200 frequency steps for integration, I'm only recording the data required for the stress plot.

Hope this helps,

Bryson