Identification of a non-proportional damping matrix-sensitivity analysis

Abstract

-1 130-CP IDENTIFICATION OF A NON-PROPORTIONAL DAMPING MATRIX-SENSITIVITY ANALYSIS Constantinos Minas* GE Corporate Research and Development Schenectady, New York 12301 Abstract A method was previously presented where a non-proportional damping matrix of a structure was uniquely identified from incomplete modal information. The approach taken was to use the reduced mass and stiffness matrices and the experimentally obtained eigenvalues and eigenvectors in a weighted least squares or a pseudo-inverse scheme (depending on the number of the equations that are available) to solve for the elements of the real, symmetric damping matrix. This method is now applied to inexact incomplete modal information. A fictitious example where the damping matrix is originally known is considered, where the elements of the exact incomplete eigenvector matrix are perturbed by a small amount up to 0.5% around the true value, to simulate noisy experimental data. The proposed method develops a non-proportional damping matrix that is a good approximation of the true viscous damping matrix, by only using a partial set of the system's perturbed eigenvalues and eigenvectors. The stability of the resulting damped model is examined.