Prediction of Frequency Response of Fully-Assembled Rotor Based on Modal Testing Data on Partially-Assembled Rotor

Abstract

This paper explores a technique for obtaining a dynamic model that can predict a fully-assembled rotor's frequency response function. This technique just requires information on the frequency response function from a partially-assembled rotor. This research uses a rotor-like test piece as a dummy rotor for modal testing. Two methods are used to implement the technique. The first method is known as a finite element model updating method and the second one is a direct model estimation method. Both methods work in the same procedure. The first step is to get an appropriate mathematical model of the dummy rotor-only. The second step is to add a mass to the mathematical model to predict the frequency response function of the dummy rotor with additional mass. Validations show that both methods can predict the frequency response of the added-mass rotor up to the third flexible-body mode. Among these, the method of model updating shows a good agreement of resonance frequency and anti-resonance frequency between the predicted model and measured data, while the method of model estimation can match the predicted model and measured data very well in terms of resonance frequency and amplitude response.