A FINITE ELEMENT UPDATING PROCEDURE USING FREQUENCY RESPONSE FUNCTIONS. APPLICATIONS TO THE MlT/SERC INTERFEROMETER TESTBED

The objectives and steps implied in a FE model updating procedure are described, with a new emphasis on the analytical frequency limits of elements. Error norms allowing the comparison of measured and predicted FP.Fs are compared, and the log-least-squares norm is shown to be particularly appropriate for FE update problems. The definition a general form of parameter uncertainty is discussed, and reanalysis is analyzed as an efficient way to evaluate the response of the updated system, particularly for structures with high modal densities. The FE model stages of the MITISERC interferometer testbed, are discussed. Component test and global dynamic updates are made for the naked supporting truss. The proposed parameter update methodology is applied for the completed testbed and gives good results. However, the limitations in the model of mission subcomponents is seen to greatly influence model error, so that the update of their properties only leads to a significant improvement in the low frequencies.