Complex mode indication function and its applications to spatial domain parameter estimation

✍ Scribed by C.Y. Shih; Y.G. Tsuei; R.J. Allemang; D.L. Brown

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 818 KB
• Volume: 2
• Category: Article
• ISSN: 0888-3270
• DOI: 10.1016/0888-3270(88)90060-x

✦ Synopsis

This paper introduces the concept of the Complex Mode Indication Function (CMIF) and its application in spatial domain parameter estimation. The concept of CMIF is developed by performing singular value decomposition (SVD) of the Frequency Response Function (FRF) matrix at each spectral line. The CMIF is defined as the eigenvalues, which are the square of the singular values, solved from the normal matrix formed from the FRF matrix, [H(jo)lH[ Z-Z&)], at each spectral line. The CMIF appears to be a simple and efficient method for identifying the modes of the complex system. The CMIF identifies modes by showing the physical magnitude of each mode and the damped natural frequency for each root. Since multiple reference data is applied in CMIF, repeated roots can be detected. The CMIF also gives global modal parameters, such as damped natural frequencies, mode shapes and modal participation vectors. Since CMIF works in the spatial domain, uneven frequency spacing data such as data from spatial sine testing can be used.

A second-stage procedure for accurate damped natural frequency and damping estimation as well as mode shape scaling is also discussed in this paper.