Laboratory for Dynamics of Machines and Structures 
Morlet-wave-based modal identification in the time domain
 I. Tomac and J. Slavič
Mechanical Systems and Signal Processing, Volume 192, June 2023, 110243

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More research on: advanced signal processing,
This research focuses on the time-domain identification of modal parameters using impact response excitation from signals with a relatively small dynamic range and high noise contamination (e.g., from high-speed cameras). The information required to identify the modal parameters is limited and is contained mostly at the beginning of the signal. In order to perform an identification from such a response, the following challenges have to be overcome: a good frequency-domain separation (for close modes), a good localisation in the time domain and an over-determination (to reduce uncertainty). To overcome these challenges this research introduces the Morlet-wave modal identification method as an extension of the Morlet-wave damping identification method, which has already proven capable of identifying the damping of short signals. Here, the method is extended to the modal parameters and an over-determination approach is proposed to reduce the uncertainty. The method identifies each mode shape separately from 10 to a maximum of 400 oscillations and at damping levels from 0.02% to 2% with a strong presence of noise in the signal. The method is tested on an experimental example and the results are compared to the classical modal identification methodology.

MSCA IF Fellow (Assoc. Prof.)

Ivan Tomac, PhD

  Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture - University of Split - Croatia
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Janko Slavič, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  +386 1 4771 226
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