Direct Versus Iterative Model Updating Methods for Mass and Stiffness Matrices

A comparative study is performed for the direct and iterative methods for updating the structural matrices based on measured data. The former was derived from the orthogonality constraints by replacing the modal vector of concern by the modal matrix in computing the correction matrices.¹The iterative method used is the improved inverse eigensenstivity method. ² Through the numerical studies, it was demonstrated that both methods yield good results. However, the direct updating method is found to be more suitable for engineering applications due to its ease in treating multi-modes and higher efficiency, especially for complicated structures.