Random Vibration and Isolators

[cbra]

I am getting ready to perform a modal and a random vibration analysis on a chassis that has vibration mounts (Lord HT2 Series).



Here is my question... Do I model the isolators to get accurate modes from the modal analysis before performing the random analysis? Or perform a modal analysis on the chassis hard-mounted and input the transmissibility curve of the isolators into the damping section of the input form for the random analysis?



If modeling the isolators...How or what type of elements have you used to simulate the isolators (rubber mounts)?



I hope this is clear!



Thanks in advance for your help.



Brian