Inference of Random Excitations from Contactless Vibration Measurements on a Panel or Membrane Using the Virtual Fields Method

O'Donoughue, Patrick; Robin, Olivier; Berry, Alain

doi:10.1007/978-3-319-76780-2_22

Cited by 3 publications

(2 citation statements)

References 14 publications

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“…Known loads were reconstructed in [22] with good accuracy for certain reconstruction window sizes which were found empirically. Deflectometry and the VFM were also used to identify pressure auto-spectra of spatially averaged random excitations in [27]. The results agreed well with microphone array measurements, except at the structural resonance frequencies and for poor signal-to-noise-ratios.…”

Section: Introductionsupporting

confidence: 52%

Full-Field Surface Pressure Reconstruction Using the Virtual Fields Method

2019

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This work presents a methodology for reconstructing full-field surface pressure information from deflectometry measurements on a thin plate using the Virtual Fields Method (VFM). Low-amplitude mean pressure distributions of the order of few O(100)Pa from an impinging air jet are investigated. These are commonly measured point-wise using arrays of pressure transducers, which require drilling holes into the specimen. In contrast, the approach presented here allows obtaining a large number of data points on the investigated specimen without impact on surface properties and flow. Deflectometry provides full-field deformation data on the specimen surface with remarkably high sensitivity. The VFM allows extracting information from the full-field data using the principle of virtual work. A finite element model is employed in combination with artificial grid deformation to assess the uncertainty of the pressure reconstructions. Both experimental and model data are presented and compared to show capabilities and restrictions of this method.

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Section: Introductionsupporting

confidence: 52%

Full-Field Surface Pressure Reconstruction Using the Virtual Fields Method

2019

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“…Transversal displacements can be then obtained by performing an inverse gradient on the slope (a spatial integration since α i (x, y) ∂w ∂i (x, y), with i = x, y). It is underlined that in the presented deflectometry measurements and other works (O'Donoughue et al, 2019a), local spatial phase variations Φ are evaluated using a phase-stepping approach with a windowed discrete Fourier transform (WDFT) algorithm (Sur and Grédiac, 2016). Other approaches could be used.…”

Section: Deflectometry Techniquementioning

confidence: 99%

Space-time reconstruction of a moving acoustic loading on a membrane by coupling the force analysis technique and full-field non-contact vibration measurements

Mougey,

Robin,

Melon

2024

Front. Acoust.

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Identifying acoustical and mechanical loadings on structures is a common problem in acoustics and vibration analysis and stationary loadings are mostly considered on plate-like structures. This work describes a proof of concept for reconstructing the trajectory of an acoustic source moving in front of a membrane. Compared with works focusing on precisely identifying a loading’s amplitude at a given location, the objective is to reconstruct the loading’s trajectory–Qualitative loading identification is sought rather than quantitative. The force analysis technique is used to recover a space-time varying loading on a structure, starting from time-resolved full-field non-contact vibration measurements conducted on a circular membrane. At the same time, a compact and tonal sound source is used to draw freehand shapes in front of the membrane. The loading trajectory, therefore, contains information that was “acoustically written”. Simple hand gestures that correspond to the drawing of a Greek letter (Σ), a capital letter (P), two shapes (♡, ⋆), and a 3-letter word (net) are recovered using the proposed procedure. The effect of various parameters on the reconstructed information is studied. Perspectives in terms of possible research areas and applications are finally discussed. These perspectives include, for example, the use of membranes to help reconstruct complex and space-time-varying loadings or even applications in musical acoustics on membranophones.

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Reconstruction of surface-pressure fluctuations using deflectometry and the virtual fields method

2020

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This study presents an approach for obtaining full-field dynamic surface-pressure reconstructions with low differential amplitudes. The method is demonstrated in a setup where an air jet is impinging on a flat plate. Deformations of the flat plate under dynamic loading of the impinging jet were obtained using a deflectometry setup that allows measurement of surface slopes with high accuracy and sensitivity. The measured slope information was then used as input for the virtual fields method to reconstruct pressure. Pressure fluctuations with amplitudes of down to O(1) Pa were extracted from timeresolved deflectometry data using temporal band-pass filters. Pressure transducer measurements allowed comparisons of the results with an established measurement technique. Even though the identified uncertainties in fluctuations were found to be as large as 50%, the spatial distributions of dynamic pressure events were captured well. Dynamic mode decomposition was used to identify relevant spatial information that correspond to specific frequencies. These dynamically important spatio-temporal events could be observed despite their low differential amplitudes. Finally, the limitations of the proposed pressure determination method and strategies for future improvements are discussed.

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Inference of Random Excitations from Contactless Vibration Measurements on a Panel or Membrane Using the Virtual Fields Method

Cited by 3 publications

References 14 publications

Full-Field Surface Pressure Reconstruction Using the Virtual Fields Method

Full-Field Surface Pressure Reconstruction Using the Virtual Fields Method

Space-time reconstruction of a moving acoustic loading on a membrane by coupling the force analysis technique and full-field non-contact vibration measurements

Reconstruction of surface-pressure fluctuations using deflectometry and the virtual fields method

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