Re-sampling of continuous scanning LDV data for ODS extraction

Castellini, Paolo; Sopranzetti, Francesca; Martarelli, Milena

doi:10.1016/j.ymssp.2015.10.035

Cited by 8 publications

(4 citation statements)

References 18 publications

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“…Now consider the situation when k s = 5, the time lag Δt = k s Δt s = 0.05 s, exceeding half of the period (or Nyquist/minimum sampling step) of the fifth and sixth modes Δt Nyq 5 ¼ 1=2f 5 ¼ 0:0458 s, Δt Nyq 6 ¼ 1=2f 6 ¼ 0:0418 s. Under this circumstance, the mode aliasing effect is induced for all three approaches so that the fifth and sixth frequencies to be identified become the aliased frequencies f aliased 5 ¼ 1=Δt À f 5 ¼ 9:0840 Hz and f aliased 6 ¼ 1=Δt À f 6 ¼ 8:0301 Hz. For more details on mode aliasing, refer to Castellini et al (2016), Yang et al (2017). Consequently, aliased frequencies f aliased 5 ,f aliased 6 rather than original frequencies f 5 and f 6 are identified, as is well verified in the diagrams of Figure 4.…”

Section: Abbreviation Descriptionsupporting

confidence: 64%

“…Under this circumstance, the mode aliasing effect is induced for all three approaches so that the fifth and sixth frequencies to be identified become the aliased frequencies f5aliased=1/Δt−f5=9.0840 Hz and f6aliased=1/Δt−f6=8.0301 Hz. For more details on mode aliasing, refer to Castellini et al (2016), Yang et al (2017). Consequently, aliased frequencies f5aliased,f6aliased rather than original frequencies f 5 and f 6 are identified, as is well verified in the diagrams of Figure 4.…”

Section: Verificationssupporting

confidence: 57%

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Covariance regression for operational modal analysis

Yang

Huang

et al. 2021

Journal of Vibration and Control

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This article proposes a covariance regression procedure for operational modal analysis. The whole work is mainly twofold. On the one hand, two identities on the covariance are presented and they reveal that the covariance at different times is linearly dependent through both scalar and matrix coefficients. On the other hand, based on the two identities, the scalar covariance regression approach and the matrix covariance regression approach are naturally invoked. In proceeding so, the scalar or matrix coefficients are first acquired through covariance regression, and then, the modal parameters are simply extracted from the coefficients. Numerical examples and a field test case are studied to see the effectiveness of the proposed covariance regression procedure, and the ability to deal with harmonic load, large damping, and closely spaced modes is clearly verified.

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Section: Abbreviation Descriptionsupporting

confidence: 64%

Section: Verificationssupporting

confidence: 57%

Covariance regression for operational modal analysis

Yang

Huang

et al. 2021

Journal of Vibration and Control

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“…The continuous scanning technology for intact areas is increasingly insufficient to meet the needs. To deal with the problem of high cyclic fatigue, it is necessary to obtain the operating deformation shape [1] (ODS) of the stress concentration area represented by the perimeter of the hole through testing. The actual dynamic deformation of a structure under forced excitation is called its ODS [2], which is also the superposition of multiple excited mode shapes of the structure.…”

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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“…However, the installation and maintenance of contact-type sensors for a large structure are complicated and expensive. Therefore, many non-contact vibration measurement techniques have been developed, for example laser-Doppler vibrometer [6], laser displacement sensor and holographic interferometry [7], etc. Although these techniques can provide non-contact and full-field measurement, they are hard to apply to large structures due to the limitations of experimental environment.…”

Section: Introductionmentioning

confidence: 99%

Output-only modal analysis of the Humen Bridge from video measurement

Lin

Wang

2022

J. Phys.: Conf. Ser.

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Video-based vibration testing is a promising non-contact method for structural health monitoring. This article develops an innovative methodology for estimating the structural modal parameters from videos without recovering the responses of structures. Firstly, an image processing (i.e., Gaussian smoothing) are adopted to smooth frames and alleviate the noises. Secondly, several regions of interest (ROIs) contained the projection area of structure are selected, and edge detection is performed to that to reduce the size of vision data. Then under some assumptions, the reduced vision data can be subjected to the frequency domain decomposition (FDD) similar to the structural modal analysis to identify the modal parameters of structure. Moreover, the structural mode shapes are recovering from such decomposition. The feasibility and accuracy of the proposed method were validated by a field experiment on the Humen Bridge in Guangzhou, China.

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Re-sampling of continuous scanning LDV data for ODS extraction

Cited by 8 publications

References 18 publications

Covariance regression for operational modal analysis

Covariance regression for operational modal analysis

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

Output-only modal analysis of the Humen Bridge from video measurement

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