Continuous scanning laser Doppler vibrometer for mode shape analysis

La, Jongpil; Choi, Jieun; Wang, Semyung; Kim, Kyoungsuk; Park, Kyihwan

doi:10.1117/1.1533794

Cited by 28 publications

(5 citation statements)

References 7 publications

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“…Most of the vibrometric systems offer point-wise measurement. And in order to measure vibrations at different points, a scanning system is used to move the measurement point rapidly and precisely on the testing surface [ 18 ]. This technique works only when the measurement conditions remain invariant during the sequential detection.…”

Section: Detector-based Idmmentioning

confidence: 99%

“…In order to measure the vibration at different points, laser Doppler vibrometers are equipped with a video camera and a scanning system. These scanning laser Doppler vibrometers (SLDV) give the possibility of moving the measurement point rapidly and precisely on the testing surface, allowing the analysis of large surface with high spatial resolution [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

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Interferometric Dynamic Measurement: Techniques Based on High-Speed Imaging or a Single Photodetector

Pedrini

2014

The Scientific World Journal

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In recent years, optical interferometry-based techniques have been widely used to perform noncontact measurement of dynamic deformation in different industrial areas. In these applications, various physical quantities need to be measured in any instant and the Nyquist sampling theorem has to be satisfied along the time axis on each measurement point. Two types of techniques were developed for such measurements: one is based on high-speed cameras and the other uses a single photodetector. The limitation of the measurement range along the time axis in camera-based technology is mainly due to the low capturing rate, while the photodetector-based technology can only do the measurement on a single point. In this paper, several aspects of these two technologies are discussed. For the camera-based interferometry, the discussion includes the introduction of the carrier, the processing of the recorded images, the phase extraction algorithms in various domains, and how to increase the temporal measurement range by using multiwavelength techniques. For the detector-based interferometry, the discussion mainly focuses on the single-point and multipoint laser Doppler vibrometers and their applications for measurement under extreme conditions. The results show the effort done by researchers for the improvement of the measurement capabilities using interferometry-based techniques to cover the requirements needed for the industrial applications.

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Section: Detector-based Idmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Interferometric Dynamic Measurement: Techniques Based on High-Speed Imaging or a Single Photodetector

Pedrini

2014

The Scientific World Journal

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“…Continuous scanning laser Doppler vibrometry (CSLDV) [3] is a spatial field measurement technique [4] that controls the laser spot to move continuously on the surface of the structure according to a predetermined scanning trajectory, while collecting all velocity responses [5]. The collected data can be processed to obtain the ODS and mode shapes of the vibrating structure [6]. As a non-contact vibration testing technique, CSLDV has been widely applied to structures with complete surfaces and regular shapes [7], such as beams [8][9][10][11] and plates [12].…”

Section: Introductionmentioning

confidence: 99%

An adaptive continuous scanning laser Doppler vibrometry technique for measuring vibrational mode shapes of structures with holes

Zhang,

Zang,

Jing

2024

Meas. Sci. Technol.

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Continuous Scanning Laser Doppler Vibrometry (CSLDV) enables fast and full-field vibration measurement in an intact area of a structure. This paper further proposes a novel adaptive CSLDV method that can obtain the Operational Deflection Shapes (ODS) and mode shape of structures with holes. Firstly, an adaptive path planning method is applied to the surface of the tested structure, which can automatically adapt to the size and position of round and square holes, as well as the resolution requirements for the measurement. Secondly, based on the symmetry and other characteristics of the planned path, the time domain signal is processed by delay optimization and demodulation to obtain the ODS of each vibration mode. Finally, a modal test is conducted on a flat structure with a square and circle holes as an example. A validation experiment is also performed using SLDV. The results show that the mode shapes obtained from both methods are consistent and the Modal Assurance Criterion (MAC) between them are all above 0.96. The method can realize CSLDV of flat plate structures with arbitrary square and round holes, and has the advantages of high efficiency and dense measurement points, which enhances its engineering applicability.

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“…This can greatly accelerate modal testing but requires specialised processing algorithms because the measurement point is constantly moving. The first measurements were from a line scan on a cantilever beam [27] (using a cross-beam LDV partly because of a mistaken view about the unsuitability of a single beam LDV), while both line and area scanning methods have since been developed using sinusoidal [23,28,29], impact [30], and pseudo-random excitation [31]. Figure 3 shows an area scan on a vehicle panel with single frequency excitation.…”

Section: Scanning Laser Doppler Vibrometry (Sldv) and Experimental Momentioning

confidence: 99%

An international review of laser Doppler vibrometry: Making light work of vibration measurement

Rothberg

Allen

Castellini

et al. 2017

Optics and Lasers in Engineering

339

153

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In 1964, just a few years after the invention of the laser, a fluid velocity measurement based on the frequency shift of scattered light was made and the laser Doppler technique was born. This comprehensive review paper charts advances in the development and applications of laser Doppler vibrometry (LDV) since those first pioneering experiments. Consideration is first given to the challenges that continue to be posed by laser speckle. Scanning LDV is introduced and its significant influence in the field of experimental modal analysis described. Applications in structural health

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Continuous scanning laser Doppler vibrometer for mode shape analysis

Cited by 28 publications

References 7 publications

Interferometric Dynamic Measurement: Techniques Based on High-Speed Imaging or a Single Photodetector

Interferometric Dynamic Measurement: Techniques Based on High-Speed Imaging or a Single Photodetector

An adaptive continuous scanning laser Doppler vibrometry technique for measuring vibrational mode shapes of structures with holes

An international review of laser Doppler vibrometry: Making light work of vibration measurement

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