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Proceedings ArticleDOI

Photoelastic analysis of stress frozen slices using five-step method

04 Dec 2009-Vol. 7522, pp 752209

TL;DR: In this paper, stress frozen 3D models are sliced mechanically and the whole field principal stress differences (Isochromatics) and principal stress directions (Isoclinics) are evaluated by capturing only five images using the standard optical arrangements of a conventional polariscope.

AbstractDigital photoelasticity is a whole field experimental technique which can analyze both 2-D and 3-D models. In this paper, stress frozen 3-D models are sliced mechanically and the whole field principal stress differences (Isochromatics) and principal stress directions (Isoclinics) are evaluated by capturing only five images using the standard optical arrangements of a conventional polariscope. The wrapped isoclinic values obtained by processing the first four colour polarization stepped images in the range -π/4 to +π/4 are unwrapped using adaptive quality guided phase unwrapping algorithm to get isoclinics in the range of -π/2 to +π/2. The total fringe order is evaluated by three fringe photoelasticity or RGB photoelasticity with its latest developments like colour adaptation combined with refined three fringe photoelasticity. The methodology is validated for two slices cut from aero-structural components.

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Citations
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Journal ArticleDOI
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.

66 citations


References
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Book
20 Oct 2008
TL;DR: The first € price and the £ and $ price are net prices, subject to local VAT as discussed by the authors, and they are subject to change without notice. All errors and omissions excepted.
Abstract: The first € price and the £ and $ price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for Germany, the €(A) includes 10% for Austria. Prices indicated with ** include VAT for electronic products; 19% for Germany, 20% for Austria. All prices exclusive of carriage charges. Prices and other details are subject to change without notice. All errors and omissions excepted.

559 citations


"Photoelastic analysis of stress fro..." refers methods in this paper

  • ...− ⎛ ⎞ − = ⎜ ⎟ − ⎝ ⎠ ⎛ ⎞ + + − + + = ⎜ ⎟ ⎜ ⎟ + + − + + ⎝ ⎠ (1)...

    [...]

  • ...(1), the subscript ‘c’ indicates that the principal value of the inverse trigonometric function is used and θc is evaluated by atan2 () function....

    [...]

Book
01 Jan 2000
TL;DR: In this article, phase shifting, Polarization Stepping and Fourier Transform Methods are used for phase unwrapping and Optically Enhanced Tiling in digital photoelasticity.
Abstract: Transmission Photoelasticity.- Reflection Photoelasticity.- Digital Image Processing.- Fringe Multiplication.- Fringe Thinning and Fringe Clustering.- Phase Shifting, Polarization Stepping and Fourier Transform Methods.- Phase Unwrapping and Optically Enhanced Tiling in Digital Photoelasticity.- Colour Image Processing Techniques.- Evaluation of Contact Stress Parameters and Fracture Parameters.- Stress Separation Techniques.- Fusion of Digital Photoelasticity, Rapid Prototyping and Rapid Tooling Technologies.- Recent Developments and Future Trends.

189 citations


"Photoelastic analysis of stress fro..." refers background in this paper

  • ...2 2 2 ( ) ( ) ( ) e c e c e c e R R G G B B = − + − + − (2) where, subscript ‘e’ refers to the experimentally measured values for the data point and ‘c’ denotes the values in the calibration table....

    [...]

Journal ArticleDOI
TL;DR: A new full-field method for the automatic analysis of isochromatic fringes in white light, named RGB photoelasticity, which makes it possible to determine retardations uniquely in the range of 0–3 fringe orders.
Abstract: In this paper a new full-field method for the automatic analysis of isochromatic fringes in white light is presented. The method, named RGB photoelasticity, eliminates the typical drawbacks of the classical approach to photoelasticity in white light which requires a subjective analysis of colors and an experienced analyst to acquire and interpret the results.

132 citations

Journal ArticleDOI
TL;DR: An overdeterministic least-squares phase-stepping method for automated photoelasticity and a three-wavelength approach to determination of the absolute value of the isochromatic parameter are shown to give reliable results.
Abstract: An overdeterministic least-squares phase-stepping method for automated photoelasticity is described. Problems associated with isochromatic–isoclinic interaction are solved by use of a three-wavelength method to calculate the value of the isochromatic parameter and the isoclinic angle. The ramped isoclinic phase map can now be unwrapped to give the orientation of the principal stresses with respect to a reference axis of the polariscope unambiguously. A three-wavelength approach to determination of the absolute value of the isochromatic parameter is shown to give reliable results also.

70 citations

Journal ArticleDOI
01 Aug 1996-Strain
TL;DR: A systematic study has been carried out on how to use the red green blue (RGB) value recorded using a colour image processing system for determining fringe orders up to 3 in a fringe field and it is revealed that instead of directly using RGB values corresponding to a dark field image, if the difference of RGB values between bright and darkfield images is used, the number of noise points is less.
Abstract: The early application of digital image processing (DIP) technique to automate photoelastic analysis is based on black and white (B & W ) image processing systems. The various methodologies reported can be traced to rely upon one or several features ofa B &W DIP system. With the advancements in computer technology, nowadays colour image processing systems are available at affordable prices. A systematic study has been carried out on how to use the red green blue (RGB) value recorded using a colour image processing system for determining fringe orders up to 3 in a fringe field. The study has revealed that instead of directly using RGB values corresponding to a dark field image, if the difference of RGB values between bright and darkfield images is used, the number of noise points is less. Experiments have been carried out for several arbitrary lines in a circular disk under diametral compression and the results are found to be good.

69 citations