A criterion for mode shape tracking: application to Campbell diagrams

The correlation criterion proposed in this article and called nc 2 o (normalized cross complex orthogonality) is based on the bi-orthogonality properties between rotor mode shapes calculated at different speeds of rotation. This criterion is proved using an industrial laminated rotor composed of disks and two fluid film bearings, whose characteristics depend on the speed of rotation. The industrial finite element model shows that the nc 2 o criterion provides a more efficient mode pairing of rotor shapes than those obtained by using classical correlation criteria. Moreover this criterion makes it easier to plot Campbell diagrams for strongly speed-of-rotation-dependent structures.