Abstract
When calculating the resonant response of bladed turbine disks, it has been convenient to assume that all blades on a given disk are identical. This leads to the prediction that all blades experience the same amplitude of displacement and stress when excited by forces harmonically related to the rotor speed. However, it has been shown experimentally that significant variations in these amplitudes occur for different blades on the same disk. These variations arise due to the effects of mistuning, which refers to small differences in characteristics between blades. In this paper, a reduced-order model is created with modal data from eigenvalue analysis in Nastran (RESVEC method). After creating a whole-blade model by component mode synthesis, eigenvalue analysis is carried out again and the modal data is sorted to pick out modal family data. This frequency analysis is faster than FEM because the final degree of freedom is equal to the number of blades. This method is verified for the 1st and 2nd mode family of a simple bladed disk with flat plate blades, and a Monte Carlo simulation is carried out. Finally, this method is applied to an actual bladed disk used in steam turbine.
