SUBMATRIX APPROACH TO STIFFNESS MATRIX CORRECTION USING MODAL TEST DATA

An efficient method for stiffness matrix correction to match modal testing data is presented. The correction is performed while preserving the connectivity of the stiffness matrix and the consistency between the stiffness matrix and the corresponding physical configuration of the structure. Significant reduction of unknown parameters is achieved by grouping the elements of the same stiffness characteristics and representing them as a multiplication of a scaling factor and a submatrix. The correction of the stiffness matrix is performed by adjusting the scaling factors. A concise formulation to identify the scaling factors is found by utilizing a least squares solution that is computationally efficient. The formulation also incorporates a capability of reducing finite element mass and stiffness matrices to test degrees-of-freedom for a direct analysis/experiment correlation. The stiffness matrix identified by this formulation produces the measured mode data accurately. The theoretical development along with a numerical example is presented to illustrate the general procedure and to demonstrate the capability of the method. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.