Some Observations on the Difficulties in Model Updating - IMAC 11

P.Avitabile, P.Li

Finite element models are updated to better represent actual measured modal characteristics. In order to represent the system properly, the finite element model should be somewhat representative of the actual system. Using frequency sensitivity approaches (which are commercially available in software), models can be updated but the accuracy of the updated model is heavily dependent on the location and the type of discrepancy that exists and is stongly influenced by the analysts understanding of the model and selection of parameters that are used for the updating process.

Simulated modal data is used to show how the sensitivity approach will update the model. The models presented are not intended to credit or discredit the approach but rather to provide a very unbiased view of the capabilities of the approach with its strengths and limitations. Models are intentionally developed that will span the full range of acceptable updated models to unacceptable updated models so that an appreciation of the technique is obtained. Forced response of an incorrectly updated model is presented to show erroneous results that may be obtained!

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