Hello,
i am studying how an hyperelastic material (siliconic rubber) affects the frequency response of a prestressed structure.
The system is composed of three aluminium plates and two rubber o-ring seals between the plates.
I am using MSC Patran/Nastran and Marc/Mentat to extract the normal modes of the prestressed structure, but i can't achieve the random solution.
The aim of my job is to obtain the RMS acceleration at the top plate, known the PSD input at the base.

Nastran SOL 111 can't handle (if i'm not wrong) hyperelastic material with ogden formulation (the one i HAVE to use), and i am not able to find a right way to perform the random analysis in marc/mentat.
I've already worked with random analysis in patran/nastran for linear jobs but, as you can see, i'm still a novice.

Can anyone address me towards useful guides or solving procedures using this programs?

Thanks