Model correlation for special types of rotor systems

The correlation between theoretical and experimental modal models can be quantified by the Modal Assurance Criterion, which has also been used for rotor systems. However, the conclusions drawn from the Modal Assurance Criterion may not be valid for non-symmetric systems since the underlying orthogonality relations are violated. Therefore, a Rotor Correlation Criterion is proposed, which incorporates right and left eigenvectors, eigenvalues, and mass and stiffness matrices. Applications of model correlation for test data assessment, sensor placement, mode pairing, and model updating are discussed in the context of rotors. For two numerical examples, the modified correlation approach is compared to the Modal Assurance Criterion. Considering the availability of experimentally determined left eigenvectors, these examples deal with a damped rotor under special support conditions and a purely gyroscopic rotor under more general conditions.