Laser-light speckle formation for deflection-shape identification using digital image correlation

Zaletelj, Klemen (author), Agrež, Vid (author), Slavič, Janko (author), Petkovšek, Rok (author), Boltežar, Miha (author)

The application of a speckle pattern to the surface of a structure is usually required for Digital Image Correlation (DIC)-based displacement identification. A speckle pattern generally requires the modification (e.g., painting) of the structure's surface. An improved method of laser-light speckle formation for DIC measurement of relatively large structures is proposed, where the speckle pattern is formed by laser-light interference as a consequence of the surface roughness and the laser illumination, leaving the surface of the object untouched. The interference phenomena caused by the light reflecting from the rough surface create bright spots that move with the observed structure. The size of the speckles depends on the surface roughness, the experimental setup and the optical system. The proposed method is researched using three experimental cases: two rigid-body motion measurements and a full-field operating-deflection-shape measurement. The experiments show that motion can be identified even when the amplitudes of the oscillation are as low as 0.1 m (on a scale of 1/1000 of a pixel). While the laser speckle accuracy is promising, it was found to be less accurate than painted speckle-pattern measurements, but with further development it could become a viable alternative.

• Language: English
• Keywords: laser speckle, paint speckle, digital image correlation (DIC), full-field vibration identification
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Author Accepted Manuscript
• Article acceptance date: 21.03.2021
• Publication date: 01.12.2021
• Year: 2021
• Number of pages: Str. 1-15
• Numbering: Vol. 161, art. 107899
• PID: 20.500.12556/RUL-126912
• UDC: 535:004.932(045)
• ISSN on article: 0888-3270
• DOI: 10.1016/j.ymssp.2021.107899
• COBISS.SI-ID: 61853187
• Publication date in RUL: 10.05.2021

Record is a part of a journal

• Title: Mechanical systems and signal processing
• Shortened title: Mech. syst. signal process.
• Publisher: Elsevier
• ISSN: 0888-3270
• COBISS.SI-ID: 169243

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
• Licensing start date: 01.12.2021

Secondary language

• Language: Slovenian
• Keywords: lasersko formiran pikčast vzorec, nanešen pikčast vzorec, visokoločljivostna identifikacija vibracijskih oblik

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: J2-1730
• Name: Polno zaznavanje prostorskih vibracij s hitro kamero z aplikacijami v digitalnih dvojčkih in oddaljenem zaznavanju

• Funder: ARRS - Slovenian Research Agency
• Project number: N2-0144
• Name: Optična metoda za obratovalno identifikacijo reduciranega nelinearnega modela