Abstract
The natural frequency calculated by a conventional beam theory technique of a stepped rotor whose diameter is not constant has a tendency to become high. For this subject, the shaft stiffness evaluation method which uses a stepped rotor shape was proposed. Concretely, after generating a solid model from the shape data of a stepped rotor, stiffness of the solid model is calculated, next, all degree of freedom of the solid model is reduced to the degree of freedom of the contact face, and high accuracy equivalent reduced model stiffness is introduced by the technique reducing the degree of freedom of the contact face to the degree of freedom of the beam model. After the verification result of a simple model by this method is described, the comparison of the numerical natural frequency and the measured result of a turbine rotor is reported.
