The Direct Updating of Damping and Stiffness Matrices

MI Friswell (University of Wales Swansea), DJ Inman & DF Pilkey (Virginia Tech)

AIAA Journal, Vol. 36, No. 3, March 1998, pp. 491-493


This note gives an extension to the standard direct methods of model updating, which estimate complete structural matrices that reproduce the measured modal data. Previous methods have not updated the damping matrix. The proposed algorithm simultaneously updates the damping and stiffness matrices of a structure, by minimising the change in these matrices, with the constraint that the measured modal data is reproduced. This approach is demonstrated using a simulated example of a cantilever beam. Three potential problems are described; positive definite updated matrices are not guaranteed, the connectivity of the original finite element model is not necessarily preserved, and extra modes may be introduced in the frequency range of interest.

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