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Title: Eulerian frequency analysis of structural vibrations from high-speed video

Abstract

An approach for the analysis of the frequency content of structural vibrations from high-speed video recordings is proposed. The techniques and tools proposed rely on an Eulerian approach, that is, using the time history of pixels independently to analyse structural motion, as opposed to Lagrangian approaches, where the motion of the structure is tracked in time. The starting point is an existing Eulerian motion magnification method, which consists in decomposing the video frames into a set of spatial scales through a so-called Laplacian pyramid [1]. Each scale — or level — can be amplified independently to reconstruct a magnified motion of the observed structure. The approach proposed here provides two analysis tools or pre-amplification steps. The first tool provides a representation of the global frequency content of a video per pyramid level. This may be further enhanced by applying an angular filter in the spatial frequency domain to each frame of the video before the Laplacian pyramid decomposition, which allows for the identification of the frequency content of the structural vibrations in a particular direction of space. This proposed tool complements the existing Eulerian magnification method by amplifying selectively the levels containing relevant motion information with respect to their frequencymore » content. This magnifies the displacement while limiting the noise contribution. The second tool is a holographic representation of the frequency content of a vibrating structure, yielding a map of the predominant frequency components across the structure. In contrast to the global frequency content representation of the video, this tool provides a local analysis of the periodic gray scale intensity changes of the frame in order to identify the vibrating parts of the structure and their main frequencies. Validation cases are provided and the advantages and limits of the approaches are discussed. The first validation case consists of the frequency content retrieval of the tip of a shaker, excited at selected fixed frequencies. The goal of this setup is to retrieve the frequencies at which the tip is excited. The second validation case consists of two thin metal beams connected to a randomly excited bar. It is shown that the holographic representation visually highlights the predominant frequency content of each pixel and locates the global frequencies of the motion, thus retrieving the natural frequencies for each beam.« less

Authors:
 [1];  [2]; ;  [3]
  1. Università Politecnica delle Marche, Piazza Roma 22, Ancona (Italy)
  2. (Belgium)
  3. Siemens Industry Software NV, Interleuvenlaan 68, B-3001 Leuven (Belgium)
Publication Date:
OSTI Identifier:
22608639
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1740; Journal Issue: 1; Conference: 12. international A.I.VE.LA. Conference on vibration measurements by laser and noncontact techniques: Advances and applications, Ancona (Italy), 29 Jun - 1 Jul 2016; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AMPLIFICATION; BEAMS; DECOMPOSITION; FILTERS; FREQUENCY ANALYSIS; HOLOGRAPHY; LAGRANGIAN FUNCTION; LAPLACIAN; METALS; NOISE; PERIODICITY; RANDOMNESS; VALIDATION

Citation Formats

Venanzoni, Andrea, Siemens Industry Software NV, Interleuvenlaan 68, B-3001 Leuven, De Ryck, Laurent, and Cuenca, Jacques. Eulerian frequency analysis of structural vibrations from high-speed video. United States: N. p., 2016. Web. doi:10.1063/1.4952662.
Venanzoni, Andrea, Siemens Industry Software NV, Interleuvenlaan 68, B-3001 Leuven, De Ryck, Laurent, & Cuenca, Jacques. Eulerian frequency analysis of structural vibrations from high-speed video. United States. doi:10.1063/1.4952662.
Venanzoni, Andrea, Siemens Industry Software NV, Interleuvenlaan 68, B-3001 Leuven, De Ryck, Laurent, and Cuenca, Jacques. Tue . "Eulerian frequency analysis of structural vibrations from high-speed video". United States. doi:10.1063/1.4952662.
@article{osti_22608639,
title = {Eulerian frequency analysis of structural vibrations from high-speed video},
author = {Venanzoni, Andrea and Siemens Industry Software NV, Interleuvenlaan 68, B-3001 Leuven and De Ryck, Laurent and Cuenca, Jacques},
abstractNote = {An approach for the analysis of the frequency content of structural vibrations from high-speed video recordings is proposed. The techniques and tools proposed rely on an Eulerian approach, that is, using the time history of pixels independently to analyse structural motion, as opposed to Lagrangian approaches, where the motion of the structure is tracked in time. The starting point is an existing Eulerian motion magnification method, which consists in decomposing the video frames into a set of spatial scales through a so-called Laplacian pyramid [1]. Each scale — or level — can be amplified independently to reconstruct a magnified motion of the observed structure. The approach proposed here provides two analysis tools or pre-amplification steps. The first tool provides a representation of the global frequency content of a video per pyramid level. This may be further enhanced by applying an angular filter in the spatial frequency domain to each frame of the video before the Laplacian pyramid decomposition, which allows for the identification of the frequency content of the structural vibrations in a particular direction of space. This proposed tool complements the existing Eulerian magnification method by amplifying selectively the levels containing relevant motion information with respect to their frequency content. This magnifies the displacement while limiting the noise contribution. The second tool is a holographic representation of the frequency content of a vibrating structure, yielding a map of the predominant frequency components across the structure. In contrast to the global frequency content representation of the video, this tool provides a local analysis of the periodic gray scale intensity changes of the frame in order to identify the vibrating parts of the structure and their main frequencies. Validation cases are provided and the advantages and limits of the approaches are discussed. The first validation case consists of the frequency content retrieval of the tip of a shaker, excited at selected fixed frequencies. The goal of this setup is to retrieve the frequencies at which the tip is excited. The second validation case consists of two thin metal beams connected to a randomly excited bar. It is shown that the holographic representation visually highlights the predominant frequency content of each pixel and locates the global frequencies of the motion, thus retrieving the natural frequencies for each beam.},
doi = {10.1063/1.4952662},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1740,
place = {United States},
year = {Tue Jun 28 00:00:00 EDT 2016},
month = {Tue Jun 28 00:00:00 EDT 2016}
}