Updating of Finite Element Models Based on a Double Condensation Procedure Using Frequency Response Functions Data

In order to take into account information from test data, not only at the resonances, but also in the other parts of the measured frequency spectrum, it is of interest to use directly measured Frequency Response Functions (FRF) instead of modal data. We also avoid by this way an experimental modal analysis. In return we have to introduce damping terms into the analytical model, we have to weight the FRF data in a systematic manner and to compute simultaneously a large amount of data. The presented procedure analyses overall these three aspects: definition of modal damping parameters, definition of weighted FRF data and condensation of the problem. This last notion is particularly pointed out. The condensation is performed in two steps : a static condensation of the model on the degrees of freedom corresponding to the location of the sensors, and a simultaneous condensation of experimental and analytical FRF data by a common transformation matrix. The first applications are performed on a simulated test case with large stiffness, mass and modal damping perturbations introduced in the initial model as well as strong noise pollution of measured responses and applied forces.