Tom,
Thanks for your reply. I'm also using NE/Nastran and use the large mass method of random response which includes a unit frequency response calculation which later gets used to do the random. I was hoping that the "simple" method of not integrating the at or near zero hertz modes associated...
I need to get random psd and rms displacements relative to the base motion of my model. The MSC/Nastran Dynamics Users Manual suggests running the random analysis at some frequency above the zero hertz mode associated with the enforced motion of the large mass. Others have used mpc equations...
