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力学学报 1993
A DIRECT EIGENSYSTEM REALIZATION ALGORITHM FOR MODAL PARAMETER IDENTIFICATION IN TIME DOMAIN
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Abstract:
A new method called direct eigensystem realization algorithm (DERA) is developed for structural modal parameter identification. A direct procedure is presented for obtaining the minimum realization of a multiple-input multiple output time-invariant discrete system from observations of the input and output in time domain, and then modal parameters are obtained from the eigenvalues and eigenvectors of the system transition matrix. Because of the use of direct input-output observations, some weaknesses of the ERA and the PRCE methods which use impulse response functions as initial data have been avoided. By using the singular-value decomposition technique, a more convenient procedure is derived to determine the minimum order and realization of the system. An example is shown to illustrate the algorithm, in which simulation data from a spring, mass and damping system of five degrees of freedom are utilized. Effectiveness of the algorithm is proved by good numerical results, and high accuracy is achieved for close-spaced frequency modes.