Model Updating

The term “model updating” describes the process of adjusting the parameters of a finite element model in order that its predictions, in terms of eigenvalues and eigenvectors, are in agreement with measurements obtained by modal testing. The sensitivity method described in this chapter has been implemented numerous times in commercial codes and applied successfully in industry. It has become a mature technology in regular use in the automotive and aerospace industries worldwide. However, there are various subtleties surrounding the application of model updating that are discussed here for the benefit of potential users. Firstly there must be an awareness of the frequency range in which the updated model is to be applied. The available data is generally insufficient to define the system parameters without the use of additional information provided by regularization. And the choice of parameters is of critical importance: it is not only a matter of choosing sensitive parameters; they should also be chosen as part of an engineering understanding of the dynamics of the system. Careful choice of parameters, together with regularization, will lead to validated models that predict the behavior of the system beyond the scope of the original test data