On the treatment of uncertainty in experimentally measured frequency response functions

Meggitt, JWR

Abstract

Frequency response functions (FRFs) are routinely used within experimental structural dynamics, among other fields. The uncertainty associated with their measurement is typically modelled on the simplified assumption that additive uncorrelated noise is present. This treatment of FRF uncertainty is questioned here by demonstrating that the notion of operator uncertainty (i.e. the uncertainty due to inconsistent force excitation) introduces a correlation between measured FRFs which is not accounted for under
the assumption of additive noise. The origin of this correlation is illustrated and its experimental presence verified. The importance of this correlation on the propagation of uncertainty is subsequently investigated as part of a numerical and experimental case study,
where its influence on the inversion of an uncertain FRF matrix is considered. It is shown that the neglect of such correlations can lead to large errors in uncertainty estimates, for example in dynamic sub-structuring and the solution of inverse problems.
Keywords: Frequency response function, structural dynamics, experimental, measurement, operator uncertainty

Citation

Meggitt, J. (2018). On the treatment of uncertainty in experimentally measured frequency response functions. Metrologia, 55(6), 806. https://doi.org/10.1088/1681-7575/aadeeb

• Journal Article Type: Article
• Acceptance Date: Sep 5, 2018
• Online Publication Date: Oct 19, 2018
• Publication Date: Oct 19, 2018
• Deposit Date: Feb 8, 2019
• Publicly Available Date: Oct 19, 2019
• Journal: Metrologia
• Print ISSN: 0026-1394
• Electronic ISSN: 1681-7575
• Publisher: IOP Publishing
• Volume: 55
• Issue: 6
• Pages: 806
• DOI: https://doi.org/10.1088/1681-7575/aadeeb
• Publisher URL: https://doi.org/10.1088/1681-7575/aadeeb
• Related Public URLs: https://iopscience.iop.org/journal/0026-1394
• Additional Information: Funders : Engineering and Physical Sciences Research Council (EPSRC); Projects : EMBED; Grant Number: EP/P005489/1