Achievable precision of close modes in operational modal analysis: Wide band theory

Au, Siu-Kui ORCID: 0000-0002-0228-1796, Li, Binbin and Brownjohn, James MW
(2021) Achievable precision of close modes in operational modal analysis: Wide band theory. MECHANICAL SYSTEMS AND SIGNAL PROCESSING, 147. p. 107016.

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This work takes up the challenge of deriving the ‘uncertainty law’ for close modes, i.e., closed form analytical expressions for the remaining uncertainty of modal parameters identified using (output-only) ambient vibration data. In principle the uncertainty law can be obtained from the inverse of the Fisher information matrix of modal parameters. The key mathematical challenges stem from analytical treatment of entangled stochastic dynamics with a large number of modal parameters of different nature and the quest for closed form expressions for identification uncertainty, whose possibility is questionable. Fortunately the problem still admits insightful closed form solution under long data, high signal-to-noise ratio and wide resonance band for identification. Up to modelling assumptions and the use of probability, the uncertainty law dictates the achievable precision of modal properties regardless of the identification algorithm used. A companion paper discusses the insights, verification, scientific implications and recommendation for ambient test planning.

Item Type: Article
Uncontrolled Keywords: Ambient modal identification, BAYOMA, Close modes, Fisher information matrix, Operational modal analysis, Uncertainty law
Depositing User: Symplectic Admin
Date Deposited: 17 Aug 2020 08:00
Last Modified: 18 Jan 2023 23:37
DOI: 10.1016/j.ymssp.2020.107016
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