Abstract:

It is necessary for some large scale structures to extract modal parameters using only ambient responses. A poly reference difference model with a cross correlation function is derived from the classical difference model in this paper. The augmented matrix method and polynomial eigenvalue method are used to get modal parameters respectively. Then an experiment on an aircraft model is done to verify the validity of the proposed method. And the results from both the augmented matrix and polynomial eigenvalue are compared. It shows that the presented method can be used to identify modal parameters effectively under ambient excitation and that the polynomial eigenvalue method is superior to the augmented matrix method.

Key words: modal ident ification, ambient excitation, cr oss-cor relation function, differ ence model, unknownexcitation, oper ating conditions