TABLE OF CONTENTS Once the modal parameters are determined, there are several procedures that allow the modal model to be validated. Some of the procedures that are used are
Measurement synthesis
Visual verification (animation)
Finite element analysis
Modal vector orthogonality
Modal vector consistency (modal assurance criterion)
Modal modification prediction
Modal complexity
Modal phase colinearity and mean phase deviation
All of these methods depend upon the evaluation of an assumption concerning the modal model. Unfortunately, the success of the validation method defines only the validity of the assumption; the failure of the modal validation does not generally define what the cause of the problem is.
The most common validation procedure is to compare the data synthesized from the modal model with the measured data. This is particularly effective if the measured data are not part of the data used to estimate the modal parameters. This serves as an independent check of the modal parameter estimation process. The visual match can be given a numerical value if a correlation coefficient, similar to coherence, is estimated. The basic assumption is that the measured frequency response function and the synthesized frequency response function should be linearly related (unity) at all frequencies.
Synthesis correlation coefficient (SCC):.
where
| H pq( ?) | = measured frequency response function |
| ? pq( ?) | = synthesized frequency response function |
Another common method of modal model validation is to evaluate the modal vectors visually. While this can be accomplished from plotted modal vectors...
