2022 Volume 43 Issue 5 Pages 260-268
The integrity evaluation of the rotor wedges of turbine generators is discussed by observing the mechanical resonant frequency shift originating from cracks. We propose a simple method of obtaining the frequency response of the inspection target using point contact piezoelectric sensors and a network analyzer. Eigenmodes are identified in both experiments and finite element analysis, and frequency responses are compared. Several resonant frequencies shift to the lower side owing to the stiffness decrease caused by the crack, and the validity and effectiveness of the method are discussed. From both measurements and finite element analysis (FEA), the modes where the crack is located in the high-stress region have a more significant shift than the mode that does not. The shift was correlated between the FEA and measurement throughout most of the modes.
