Photogrammetry and optical methods in structural dynamics – A review

Baqersad, Javad; Poozesh, Peyman; Niezrecki, Christopher; Avitabile, Peter

doi:10.1016/j.ymssp.2016.02.011

Cited by 415 publications

(172 citation statements)

References 76 publications

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“…More in details, photogrammetry is a contact-less measurement approach that uses a series of recorded images to identify coordinates of points, patterns, and features in the images or to detect the boundaries of objects [17]. A series of images enables the operation of tracking the motion of a given measurand, hence vibration monitoring can be carried out by means of vision based techniques.…”

Section: Camera Based Measurement Operating Principlementioning

confidence: 99%

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Uncertainty in vision based modal analysis: probabilistic studies and experimental validation

Lavatelli

Zappa

2016

ACTA IMEKO

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This paper analyses the issues related with the application of photogrammetric methods in the context of modal analysis. In this field of mechanical testing, the vibrations of the measurand are monitored. The possibility to measure displacement of several monitored points without directly instrumenting those, pushes the interest toward the application of an image based measurement system. However, the process of acquiring a moving target with a camera is complex due to the motion blur phenomenon. The effects of this particular phenomenon on uncertainty generation and propagation are discussed in parallel with Monte Carlo simulation and experimental approach. The case study here proposed focuses on the estimation of the main modal parameters (first two resonant frequencies and amplitudes) of a structure with the help of 2D Blob Analysis, with particular focus in comparing the performances of photogrammetry with the ones of classic motion transducers. The results of both the approaches confirm that the choice of using photogrammetry as an input for modal analysis should be made carefully, since the actual behavior of a structure can be distorted. Nonetheless, the results show that particular care should be made in the choice of structural excitation when using vision based techniques.

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Section: Camera Based Measurement Operating Principlementioning

confidence: 99%

“…The fore mentioned sources do not appear on calibration only, since they appear also on the generic image of the measurand. When recording moving objects other problems gather with the fore mentioned ones, in particular camera synchronization and motion blur [17].…”

Section: Camera Based Measurement Operating Principlementioning

confidence: 99%

Uncertainty in vision based modal analysis: probabilistic studies and experimental validation

Lavatelli

Zappa

2016

ACTA IMEKO

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“…This paper aims to present a summary of key work in the field of vision-based systems for structural displacement monitoring while highlighting the principles, advantages and shortcomings of these systems. Although previous reviews of vision-based structural monitoring exist [27][28][29], the contribution of this work is to provide an overview of system classifications, methodologies and applications in field monitoring.…”

Section: Introductionmentioning

confidence: 99%

Review of machine-vision based methodologies for displacement measurement in civil structures

Brownjohn

2017

J Civil Struct Health Monit

254

125

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Vision-based systems are promising tools for displacement measurement in civil structures, possessing advantages over traditional displacement sensors in instrumentation cost, installation efforts and measurement capacity in terms of frequency range and spatial resolution. Approximately one hundred papers to date have appeared on this subject, investigating topics like system development and improvement, the viability on field applications and the potential for structural condition assessment. The main contribution of this paper is to present a literature review of vision-based displacement measurement, from the perspectives of methodologies and applications. Video-processing procedures in this paper are summarised as a three-component framework: camera calibration, target tracking and structural displacement calculation. Methods for each component are presented in principle, with discussions about the relative advantages and limitations. Applications in the two most active fields, bridge deformation and cable vibration measurement, are examined followed by a summary of field challenges observed in monitoring tests. Important gaps requiring further investigation are presented, e.g. robust tracking methods, non-contact sensing and measurement accuracy evaluation in field conditions.

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“…Digital Image Correlation (DIC) as a non-contact measurement technique is recently emerging and has been used for structural health monitoring of wind turbine blades [1][2][3][4], helicopter rotors [5][6][7][8], aircraft fuselages, and bridges [9,10]. However, for a DIC measurement, a pattern needs to be created on the entire surface of the structure.…”

Section: Introductionmentioning

confidence: 99%

Modal Expansion using Strain Mode Shapes

Baqersad

Bharadwaj

Poozesh

2017

Shock &Amp; Vibration, Aircraft/Aerospace, Energy Harvesting, Acoustics &Amp; Optics, Volume 9

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Reduction/expansion approaches have been conventionally used in correlation and validation studies. Recently, these approaches have also been used to extract full-filed results on structures using limited set of data measured. The expansion techniques are used to expand real-time data measured on components of vehicle chassis, utility scale wind turbines, and helicopter rotors. The resulted full-field data is used to monitor structures and determine their durability. With the advances in Digital Image Correlation (DIC), researchers are able to readily extract strain mode shapes of structures. However, the conventional reduction/expansion techniques are usually limited to displacement, velocity, or acceleration data. This can hinder correlation studies that compare the strain data between two models. Furthermore, this limitation does not allow researchers to expand strain-gage measured data for full-field structural monitoring and durability analysis.In the current paper, a reduction/expansion technique has been developed to reduce/expand strain data. In this technique, measured strain at limited locations is expanded using strain mode shapes to extract full-field results on the entire surface and within the structure. This technique can also be used to reduce data for correlation studies. In order to demonstrate the merit of the approach, the proposed strain expansion approach was applied to the finite element model of a cantilever beam subjected to sinusoidal and impact excitations. The results show that the proposed approach can effectively expand the strain measured at limited locations. The approach could accurately predict the strain at locations where no sensors were placed. Keywords Modal expansion • Strain mode shapes • Structural health monitoring • Modal analysis • Expansion methodology Nomenclature S nFull-space strain vector RTOS a Real-time operating strain in reduced-space V n Full-space strain mode shape matrix U n Full-space displacement mode shape matrix T Transformation matrix X n Full-space displacement vector RTOS en Real-time operating strain in full-space V a Reduced-space strain mode shape matrix P Mode contribution vector V g a

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Photogrammetry and optical methods in structural dynamics – A review

Cited by 415 publications

References 76 publications

Uncertainty in vision based modal analysis: probabilistic studies and experimental validation

Uncertainty in vision based modal analysis: probabilistic studies and experimental validation

Review of machine-vision based methodologies for displacement measurement in civil structures

Modal Expansion using Strain Mode Shapes

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