Comparison of FRF measurements and mode shapes determined using optically image based, laser, and accelerometer measurements

Warren, Christopher; Niezrecki, Christopher; Avitabile, Peter; Pingle, Pawan

doi:10.1016/j.ymssp.2011.01.018

Cited by 115 publications

(50 citation statements)

References 6 publications

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“…However, installing a number of them on to a structure becomes expensive, with associated cabling infrastructure for power and data and/or additional wireless equipment. Data from standard accelerometers may also not measure very low frequency vibrations [5].…”

Section: Structural Testingmentioning

confidence: 99%

See 1 more Smart Citation

Monitoring Dynamic Structural Tests Using Image Deblurring Techniques

McCarthy

Chandler

Palmeri

2013

KEM

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Photogrammetric techniques have demonstrated their suitability for monitoring static structural tests. Advantages include scalability, reduced cost, and three dimensional monitoring of very high numbers of points without direct contact with the test element. Commercial measuring instruments now exist which use this approach. Dynamic testing is becoming a convenient approach for long-term structural health monitoring. If image based methods could be applied to the dynamic case, then the above advantages could prove beneficial. Past work has been successful where the vibration has either large amplitude or low frequency, as even specialist imaging sensors are limited by an inherent compromise between image resolution and imaging frequency. Judgement in sensor selection is therefore critical. Monitoring of structures in real-time is possible only at a reduced resolution, and although imaging and computer processing hardware continuously improves, so the accuracy demands of researchers and engineers increase. A new approach to measuring vibration is introduced here, whereby a long-exposure photograph is used to capture a blurred image of the vibrating structure. The high resolution blurred image showing the whole vibration interval is measured with no need for high-speed imaging. Results are presented for a series of small-scale laboratory models, as well as a larger scale test, which demonstrate the flexibility of the proposed technique. Different image processing strategies are presented and compared, as well as the effects of exposure, aperture and sensitivity selection. Image processing time appears much faster, increasing suitability for real-time monitoring.

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Section: Structural Testingmentioning

confidence: 99%

“…Image-based monitoring has proven its application in the past to monitoring structural tests [5][6][7][8]. A structure is measured using photogrammetric techniques and data compared at different time intervals to calculate displacements.…”

Section: Imagery-based Monitoring Of Structuresmentioning

confidence: 99%

Monitoring Dynamic Structural Tests Using Image Deblurring Techniques

McCarthy

Chandler

Palmeri

2013

KEM

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“…The full assembly is very compact and much smaller than its predecessor. The solid metallic body (3) supports a small electric motor (1) and the scanning head (2). An alignment system (4) is connected to the solid body by a set of screws, which allows the alignment of the head of the fibre optic laser probe.…”

Section: Dof Scanning Devicementioning

confidence: 99%

“…Warren et al 2 produced a paper which compares vibration measurements obtained using conventional accelerometers, SLDV, and DIC methods. It is clear that the use of the latter one increases the number of measurement points very much and these being captured at the same time make the measurement very time efficient.…”

Section: Introductionmentioning

confidence: 99%

Experimental validation of a newly designed 6 degrees of freedom scanning laser head: Application to three-dimensional beam structure

Maio

Copertaro

2013

Review of Scientific Instruments

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A new scanning laser head is designed to use single Laser Doppler Vibrometer (LDV) for performing measurements up to 6 degrees of freedom (DOF) at a target. The scanning head is supported by a rotating hollow shaft, which allows the laser beam to travel up to the scanning head from an opposite direction where an LDV is set up. The scanning head is made of a set of two mirrors, which deflects the laser beam with an angle so that the rotation of the scanning head produces a conical scan. When measurements are performed at the focal point of the conical scan then three translational vibration components can be measured, otherwise the very small circle scan, before and after the focal point, can measure up to 6 degrees of freedom, including three translations and three rotations. This paper presents the 6DOF scanning head and the measurements of 3D operational deflection shapes of a test structure.

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“…Research into this subject is ongoing with several studies comparing the more traditional modal testing methods, such as roving hammer tests using accelerometers, with these non-contact optical approaches [31,36] as well as work being undertaken to develop the new data processing and correlation methods necessary to account for large amounts of data gathered from the full field of interest [37][38][39].…”

mentioning

confidence: 99%