SYSTEM MODAL IDENTIFICATION USING FREE VIBRATION DATA

System modal identification for structures is a fundamental problem in structural dynamics. The identified natural frequencies, damping ratios and mode shapes can be used to better understand the behaviour of structures, modify structures, design control system for structures, and can also be used in direct analysis of structures. A time domain method for identification of modal parameters for a test structure using free vibration responses is presented in this paper. The method in based on the multidimensional autoregressive model of a vibrating structure. The method is efficient with computing time and has the advantage of being able to identify very close natural frequencies and highly coupled modes. A numerical example and a test case are used to illustrate the usefulness and results of the method.