Accuracy of the Sampling Moiré Method and its Application to Deflection Measurements of Large-Scale Structures

Ri, Shien; Muramatsu, Takashi; Saka, Masumi; Nanbara, Kenichi; Kobayashi, Daisuke

doi:10.1007/s11340-011-9491-2

Cited by 68 publications

(30 citation statements)

References 23 publications

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“…As already mentioned in the case of decal paper, such a solution is, however, not adapted in case of cracks. In large‐scale structures, grids can be painted directly onto the surface, as in where pitches equal to 38.5 mm were obtained with this simple technique.…”

Section: Marking Surfaces With Gridsmentioning

confidence: 99%

“…In this case, d 1 = 0.5 in Equation . In this example, with the values of the parameters given earlier, we have K = 2 13 . For d 1 ε , the synthetic phase distribution is a sine wave whose period

\frac{1}{f^{'}}

lies between twice the grid pitch and 15 times the grid pitch (with values that are multiples of the pitch), thus

\frac{1}{f^{'}} \in

pixels. This pitch can be considered as a parameter, and we can observe its influence on the bias. For d 2 ε , the bias evolves stepwise from 0.1 to 0.2 (we chose small values because users generally want a low bias in their measurements), so we have two parameters influencing the response, σ which lies between 5 and 10 pixels, and λ between 0.1 to 0.2. This value for the standard deviation in the image is similar to that observed on average with the 16‐bit image shot with the CCD camera used in Ref.…”

Section: Metrological Performancementioning

confidence: 99%

“…This issue is discussed also in Refs. concerning the sampling moiré. We propose here an in‐depth discussion on this point.…”

Section: Introductionmentioning

confidence: 99%

“…The idea here is to give some examples of use of the grid method in experimental mechanics, in situations for which it is relevant to measure displacement and strain fields to characterise the mechanical properties of materials and structures. Even though grids are reported to be used as local displacement transducers, see, for instance, in the case of large structures such as pipes of power plants or for ceiling travelling cranes, fields of measurements are generally obtained and analyzed with this technique.…”

Section: Introductionmentioning

confidence: 99%

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The Grid Method for In‐plane Displacement and Strain Measurement: A Review and Analysis

Grédiac

Sur

Blaysat

2016

Strain

139

162

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The grid method is a technique suitable for the measurement of in-plane displacement and strain components on specimens undergoing a small deformation. It relies on a regular marking of the surfaces under investigation. Various techniques are proposed in the literature to retrieve these sought quantities from images of regular markings, but recent advances show that techniques developed initially to process fringe patterns lead to the best results. The grid method features a good compromise between measurement resolution and spatial resolution, thus making it an efficient tool to characterise strain gradients. Another advantage of this technique is the ability to establish closed-form expressions between its main metrological characteristics, thus enabling to predict them within certain limits. In this context, the objective of this paper is to give the state of the art in the grid method, the information being currently spread out in the literature. We propose first to recall various techniques that were used in the past to process grid images, to focus progressively on the one that is the most used in recent examples: the windowed Fourier transform. From a practical point of view, surfaces under investigation must be marked with grids, so the techniques available to mark specimens with grids are presented. Then we gather the information available in the recent literature to synthesise the connection between three important characteristics of full-field measurement techniques: the spatial resolution, the measurement resolution and the measurement bias. Some practical information is then offered to help the readers who discover this technique to start using it. In particular, programmes used here to process the grid images are offered to the readers on a dedicated website. We finally present some recent examples available in the literature to highlight the effectiveness of the grid method for in-plane displacement and strain measurement in real situations.

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Section: Marking Surfaces With Gridsmentioning

confidence: 99%

\frac{1}{f^{'}}

lies between twice the grid pitch and 15 times the grid pitch (with values that are multiples of the pitch), thus

\frac{1}{f^{'}} \in

Section: Metrological Performancementioning

confidence: 99%

“…This issue is discussed also in Refs. concerning the sampling moiré. We propose here an in‐depth discussion on this point.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Grid Method for In‐plane Displacement and Strain Measurement: A Review and Analysis

Grédiac

Sur

Blaysat

2016

Strain

139

162

View full text Add to dashboard Cite

show abstract

“…These techniques are the Geometric Phase Analysis (GPA) [12], the windowed version of GPA (WGPA) [13] and the Localized Spectrum Analysis (LSA) [10]. A fourth technique named sampling moiré has been proposed to process grid images in the recent past [14,15,16]. Employing it for checkerboard images seems however not possible.…”

Section: Introductionmentioning

confidence: 99%

Comparing several spectral methods used to extract displacement fields from checkerboard images

Grédiac

Blaysat

Sur

2020

Optics and Lasers in Engineering

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Checkerboard represents the best pattern for in-plane displacement measurement in terms of sensor noise propagation because this pattern maximizes image gradient. It also exhibits other interesting properties in terms of pattern-induced bias for instance. Digital Image Correlation (DIC) is not the best option to extract displacement fields from such periodic patterns, and spectral methods should be used instead. In this paper, it is shown that three different spectral techniques initially developed for classic bidimensional grids can be adapted to process checkerboard images. These three techniques are the Geometric Phase Analysis (GPA), the windowed version of the Geometric Phase Analysis (WGPA), and the Localized Spectrum Analysis (LSA), which can be regarded as the ultimate version of WGPA. The main features of these three techniques as well as the link between them are given in this paper. Their metrological performance are compared in terms of displacement resolution, spatial resolution and bias. Synthetic checkerboard images deformed with a suitable reference displacement field are considered for this purpose. It is shown that GPA is the fastest method. According to the metric used in this paper, the best metrological performance is obtained with WGPA with suitable settings. LSA followed by a deconvolution algorithm is just behind, but the calculation time is approximately 10 times lower than that of WGPA for the examples considered in this paper, which makes it a reasonable choice for the determination of in-plane displacement fields from checkerboard images.

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Dynamic Thermal Deformation Measurement Technique for Large-Scale High Temperature Piping

Saka

Nanbara

et al. 2012

Conference Proceedings of the Society for Experimental Mechanics Series

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Accuracy of the Sampling Moiré Method and its Application to Deflection Measurements of Large-Scale Structures

Cited by 68 publications

References 23 publications

The Grid Method for In‐plane Displacement and Strain Measurement: A Review and Analysis

The Grid Method for In‐plane Displacement and Strain Measurement: A Review and Analysis

Comparing several spectral methods used to extract displacement fields from checkerboard images

Dynamic Thermal Deformation Measurement Technique for Large-Scale High Temperature Piping

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