Dynamic Modeling of Rotors: A Modal Approach
Dynamic modeling of rotors is usually performed under the assumption that the rotating parts of the machine are axially symmetrical, while the non-rotating ones may have no particular symmetry properties. The rotor model, based on the FEM, can be reduced in modal form and then assembled in the FEM model of the stator of the machine. Different rotors, rotating at different speeds, can be assembled on the same stator, even if the rotors are not coaxial. The rotor need not to be axially symmetrical, a cyclic symmetry of order 3 or higher being required. Modal modeling of rotors is dealt with in detail, and an example shows the effects of modal truncation on the precision of the results for a rotor with substantial gyroscopic and non-rotating damping effects. The algorithms are here developed for 1-D and 11/2-D beamlike rotors models but generalization to full 3-D modeling is possible.
KeywordsRotordynamics FEM modeling Modal component synthesis
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