rotor stiffness modeling

[chjura]

Hello
I'm looking for information about stiffness modeling of the rotor in the area of large diameter changes.

The rotor model I am using is diveded in elements and every element is defined with its iner/outer mass and stiffness diameters. The mass diameters follow the contour of the rotor and for the stiffness diameter we are using "45 degree rule", i.e. if there is a step change of the rotor diameter we approximate the stiffness diameter by increasing it gradually.

This approach however is not applicable for every rotor geometry (the angle could vary between 30 and 60 degree).
I have proposed to run FE analysis and get a bending line of the rotor. Then adjust the stiffness of the rotor-dynamic model to match the bending line of the dynamic model to the FE model. But I was told that this is "to complicated".

So my question is:
Is there any book, paper or standard about estimating the rotor stiffness in the area of large diameter changes?

 

[magicme]

hi there
if you have finite element capability, why not simply model the rotor and do a modal analysis? but, if the real intent is to correlate your analysis practice with FEA results.....that could go on forever and still never meet everyone's satisfaction....so in that regard i would agree that's "too complicated".
but doing modal analysis or rotors by FEA is not outrageously complicated.....though there can be death in the details (bearing and support stiffness ? ..... is a forced response analysis called for?...are there forces other than unbalance at work?....etc etc)

daveleo