Eigenvalue buckling stress stiffness matrix

[cgswai]

I have been asked to do an eigenvalue buckling analysis of an externally loaded pressure vessel (a submersible). The primary loading is obviously the hydrostatic pressure but there is also a number of other loads which do not vary with depth.
Can anyone tell me if there a way of using only the stress stiffness matrix accociated with the pressure loading without also scaling the other non-variable loads in the eigenvalue buckling problem?

Thanks in advance for any advice offered.

 

[jmg2004]

In the Ansys Help it is explained how to do that. There is shown the case of an aplied force and gravity (that is constant).
You must scale your forces until the buckling coeff. is 1. (you must iterate manually)

 

[cgswai]

Thanks for the reply.
I am aware of the iterative approach described in the manual, i was just hoping there was a more automated approach to the problem. I would ideally like to be able to extract the first fifty modes but given the size of the problem it would be a real pain to to this manually.