Digital photoelasticity – A comprehensive review
10 Jun 2011-Journal of Strain Analysis for Engineering Design (SAGE Publications)-Vol. 46, Iss: 4, pp 245-266
TL;DR: This review thematically classifies all the developments in digital photoelasticity and highlights the relative merits and drawbacks of the various techniques to allow an end-user to make an informed choice on the type of technique to be used in a particular situation.
Abstract: Digital photoelasticity has rapidly progressed in the last few years and has matured into an industry-friendly technique. This review thematically classifies all the developments in digital photoelasticity and highlights the relative merits and drawbacks of the various techniques. The overall objective is to provide enough information and guidance to allow an end-user to make an informed choice on the type of technique to be used in a particular situation.
Citations
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TL;DR: The article presents an overview of the main characteristics of RGB photoelasticity that is influence of the quarter-wave plate error, number of acquisitions, type of light source, determination of low and high fringe orders, methods for searching the retardation, scanning procedures, calibration on a material different from that under test, combined use of the RGB and phase shifting methods.
66 citations
TL;DR: In the last three decades of developments, the technique of Digital Photoelasticity (DP) has been stabilized and the methodology has successfully applied to a wide range of problems in Engineering and science as discussed by the authors.
56 citations
TL;DR: In this article, the authors used 3D printed models based on X-ray microfocus computed tomography (CT) imaging of a concrete sample to replicate its complex aggregate structure in a transparent matrix, and the associated three-dimensional stress field is visually characterized at mesoscale through uniaxial compression tests and photoelastic techniques that incorporate a threedimensional frozen-stress test to analyse the effects of randomly distributed aggregates.
53 citations
TL;DR: The recent advances in digital photoelasticity have made it possible to use it conveniently for the stress analysis of articles and components made of glass as discussed by the authors, which necessitates different techniques and associated equipments.
51 citations
TL;DR: This work presents a new digital photoelasticity Reference EPFL-ARTICLE-222716 that combines holographic interferometry and digital image correlation for Fringe projection profilometry with real-time information about the response of the human eye to light.
38 citations
References
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TL;DR: A new phase-shifting method that can be applied under these constraints is proposed and it is shown that four phase steps are sufficient to determine both the isoclinic and the isochromatic parameters.
Abstract: In many laboratories of universities and industrial organizations, commercial polariscopes have the feature that the relative position of the two quarter-wave plates is fixed. This is due to the requirement of transforming a plane polariscope to a circular polariscope with greater precision and ease. Unfortunately, these polariscopes cannot implement Patterson and Wang's [Strain 27, 49-56 (1991)] phase-shifting algorithm because this algorithm requires that the second quarter-wave plate and the analyzer of the circular polariscope be capable of independent rotation. A new phase-shifting method that can be applied under these constraints is proposed. A comparative study with Patterson and Wang's [Strain 27, 49-56 (1991)] algorithm shows very good agreement. Furthermore, it is shown that four phase steps are sufficient to determine both the isoclinic and the isochromatic parameters.
42 citations
TL;DR: This work has improved the standard demodulation algorithm used in RGB calibration by changing the Euclidean cost function to a regularized one in which the fidelity term corresponds to the Euclidan distance between RGB triplets; the regularizing term forces piecewise continuity for the isochromatic retardation.
Abstract: The red-blue-green (RGB) calibration technique consists in constructing an a priori calibration table of the isochromatic retardation versus the triplet of RGB values obtained with a RGB CCD camera. In this way a lookup table (LUT) is built in which the entry is the corresponding RGB triplet and the output is the given retardation. This calibration (a radiometric quantity) depends on the geometric and chromatic parameters of the setup. Once the calibration is performed, the isochromatic retardation at a given point of the sample is computed as the one that minimizes the Euclidean distance between the measured RGB triplet and the triplets stored in the LUT. We present an enhanced RGB calibration algorithm for isochromatic fringe pattern demodulation. We have improved the standard demodulation algorithm used in RGB calibration by changing the Euclidean cost function to a regularized one in which the fidelity term corresponds to the Euclidean distance between RGB triplets; the regularizing term forces piecewise continuity for the isochromatic retardation. Additionally we have implemented a selective search in the RGB calibration LUT. We have tested the algorithm with simulated as well as real photoelastic data with good results.
42 citations
TL;DR: In this article, the general characteristics of phase shifting photoelasticity in the colour domain were investigated, focusing on the influence of spectral content of the light source, the spectral response of the colour camera filters, the dispersion of the birefringence and the error of quarter wave plates.
42 citations
TL;DR: In this paper, a phase-measuring method is proposed for stress separation in two-dimensional interferometric photoelasticity, where a Mach-Zehnder-type interferometer combined with a circular polariscope is used for the observation of isochromatics and isoclinics.
Abstract: A phase-measuring method is proposed for stress separation in two-dimensional interferometric photoelasticity. A Mach–Zehnder-type interferometer combined with a circular polariscope is used for the observation of isochromatics and isoclinics as well as isopachics. Phase-stepping is performed for the determination of the phase values of isochromatics and isoclinics by rotating both a quarter-wave plate and an analyser. On the other hand, the phase of the isopachics is analysed from images obtained by shifting a mirror in the interferometer. Then, the phases of isochromatics and isoclinics without ambiguity are obtained by introducing a load-stepping technique. The phases obtained by the load-stepping are also used for unwrapping the phases of isochromatics and isopachics. In the present paper, light intensity equations for the proposed optical set-up are derived using Jones calculus. Then, the effectiveness is demonstrated by applying the proposed method to a simple problem.
39 citations
TL;DR: In this paper, the effect of using white light has been investigated both by experiment and by a simulation of a polariscope, and the simulation has been validated and used to explore the use of bandwidth filters to control the errors caused by white light.
Abstract: In automated photoelasticity, there are some advantages in using white light; however, the theory underlying many such systems, namely phase stepping, is based on monochromatic light The effect of using white light has been investigated both by experiment and by a simulation of a polariscope The simulation has been validated and used to explore the use of bandwidth filters to control the errors caused by using white light These errors were found to be dependent on the form of the spectrum of the light and to be large for high fringe orders
39 citations