A Mass and Stiffness Matrix Identification Technique from Incomplete Models

The paper deals with the problem of identifying the mass and stiffness matrices by an incomplete set of estimated eigenvectors. By using the pseudo-inverse of the rectangular eigenvector matrix it is possible to achieve maw and stiffness matrices with the same order of the degrees of freedom, but with the rank equal to the number of the considered modes. On the contrary, this method allows one to identify, at least for some models, the actual mass and stiffness matrices. Some numerical examples, carried out on lumped parameter system and on a cantilever beam, are presented.