I'm trying a random response analysis for the first time. (I'm familiar with harmonic response, modal analysis etc)
I have some measured acceleration PSD data in x/y/z directions, at one point on my structure so I want to apply a different PSD to each vibration direction and get the response to this combined excitation.
Could anyone provide a description the basic principles? Examples only seem to deal wiht the single-PSD case.
The area I am struggling with is the Correlation Table input page in Femap (11.4). The help says:
"you must decide whether you want to correlate the cases. If you don't enter any values for real and imaginary values, the cases will not be correlated. If you do want to correlate the cases, enter the real and imaginary factors and PSD functions"
Appreciate any insight you can offer! Whats the significance of correlating the cases?