J-017

System Identification Using IDFT for Structural Dynamic Models

Authors: Hyeung Yun Kim
Affiliation: Senior Researcher, Changwon Proving Ground, Agency for Defense Development, Republic of Korea

Abstract
The structural vibration systems expressed with the partial differential equations are considered as the infinite-dimensional dynamic system. In multi-variate control systems, it is necessary to derive the state-space reduced order model. The subspace system can be derived by eigensystem realization algorithms (ERA) methods with the inverse discrete Fourier transformation (IDFT) of the measured frequency functions. The modal coordinate transformation is applied to the realization system in order to determine the natural frequencies and modal damping ratios of the subapce system. We discuss the necessary conditions of the convergence in H_infty for the approximated transfer function of the IDFT-realization system. The error bounds of the transfer function approximation are also represented in terms of the singular values of the impulse response matricies. The structural vibration test for a smart structure and the finite element model (FEM) simulation are performed to provide the records of frequency response functions.

Hyeung Y. Kim
hyukim@postech.ac.kr