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.
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TL;DR: The existing scanning schemes are critically evaluated for their ability to scan the entire model domain, influence of seed point selection and noise propagate, which makes them suitable especially for problems where recording multiple images is difficult.
17 citations
TL;DR: In this article, the authors describe a CAE approach which combines finite element simulations and automatic photoelastic investigations for the stress analysis of face gear drives, made by stereolithography.
Abstract: The use of numerical and experimental methods to determine the stress field of mechanical components is well known. In particular, 3D photoelasticity can be considered the only experimental technique for the complete stress state evaluation of 3D components. The advent of rapid prototyping techniques has allowed the manufacturing of complex models in a matter of hours by using birifrangent materials. The present paper is focused on the description of a Computer Aided Engineering (CAE) approach which combines Finite Element (FE) simulations and automatic photoelastic investigations for the stress analysis of face gear drives, made by stereolithography. Computer Aided Design (CAD) geometries, used to manufacture the stereolithographic models, are directly used to perform FE analyses, thus allowing the stress analysis process to become simpler and easier. The substantial agreement observed between experimental and numerical results proved the potentialities of the adopted approach and the usefulness of FE simulations to optimize photoelastic analyses through cost- and time-effective experiments even for complex 3D shapes.
17 citations
Cites methods from "Digital photoelasticity – A compreh..."
...The advent of digital image processing techniques (digital photoelasticity) [2] has allowed photoelastic analyses to become faster and more accurate....
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...the various procedures proposed in literature in order to recover the isochromatic parameter [2], the...
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TL;DR: In this paper, the thermal boundary conditions (BCs) of a glass disk specimen for three different cooling rates are evaluated by measuring the residual birefringence of the glass disk with digital photoelasticity.
Abstract: Process parameters of Precision Glass Molding (PGM) are often sought by Finite Element (FE) simulation. Mechanical as well as thermal boundary conditions (BCs) are necessary for FE simulation in which mechanical BCs are usually known or easily determinable. However, most of the thermal BCs are generally assumed in the FE simulation as they cannot be measured directly. The focus of this article is to propose a novel method for evaluating the thermal BC of glass–N2 gas. FE simulations as well as thermal cycling experiments are carried out for a glass disk specimen for three different cooling rates. CFD analysis of N2 flow in the PGM machine is performed to understand the heat extraction mechanism. Based on this, adhoc values for equivalent heat transfer coefficient (heqv) are obtained by lumped system analysis. A novel methodology is then proposed for obtaining accurate heqv values by measurement of integrated residual birefringence in glass using digital photoelasticity. FE simulation is repeated for different values of heqv until the integrated birefringence based on simulation matches with that of the experiment. For the same cooling rates, two aspherical glass lenses are molded and their residual birefringence is measured and compared with the glass disk specimen.
15 citations
TL;DR: In this paper, a method to determine the stress distribution by means of phase shifting and a modified shear-difference is proposed, which is an effective method for evaluating the stress and its spatial variations within a stressed body.
Abstract: Photoelasticity is an effective method for evaluating the stress and its spatial variations within a stressed body. In the present study, a method to determine the stress distribution by means of phase shifting and a modified shear-difference is proposed. First, the orientation of the first principal stress and the retardation between the principal stresses are determined in the full-field through phase shifting. Then, through bicubic interpolation and derivation of a modified shear-difference method, the internal stress is calculated from the point with a free boundary along its normal direction. A method to reduce integration error in the shear difference scheme is proposed and compared to the existing methods; the integration error is reduced when using theoretical photoelastic parameters to calculate the stress component with the same points. Results show that when the value of Δx/Δy approaches one, the error is minimum, and although the interpolation error is inevitable, it has limited influence on the accuracy of the result. Finally, examples are presented for determining the stresses in a circular plate and ring subjected to diametric loading. Results show that the proposed approach provides a complete solution for determining the full-field stresses in photoelastic models.
14 citations
References
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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.
579 citations
TL;DR: A new phase unwrapping algorithm is described that uses local phase information to mask out those parts of the field that cause inconsistencies in the unwraps and can produce an approximately correct unwrapped.
Abstract: A new phase unwrapping algorithm is described that uses local phase information to mask out those parts of the field that cause inconsistencies in the unwrapping. Unlike earlier techniques, which produce only a consistent unwrapping of the phase in the presence of discontinuities, this technique can produce an approximately correct unwrapping. The technique is tolerant of discontinuities and noise in the phase and is fast, efficient, and simple to implement. In the absence of discontinuities an rms signal-to-noise ratio in the wrapped phase of <2:1 can be tolerated.
279 citations
TL;DR: The design of a automated system for photoelastic analysis of complex components and the potential of the system for providing detailed data over the full field of view is demonstrated by the analysis of a slice from a model of a bolt.
Abstract: The design of a automated system for photoelastic analysis of complex components is described, and an outline of the theory used in its operation is given. The potential of the system for providing detailed data over the full field of view is demonstrated by the analysis of a slice from a model of a bolt.
221 citations
TL;DR: A two-dimensional regularized phase-tracking technique that is capable of demodulating a single fringe pattern with either open or closed fringes and gives the detected phase continuously so that no further unwrapping is needed over the detectedphase.
Abstract: We present a two-dimensional regularized phase-tracking technique that is capable of demodulating a single fringe pattern with either open or closed fringes. The proposed regularized phase-tracking system gives the detected phase continuously so that no further unwrapping is needed over the detected phase.
207 citations
Book•
01 Jan 2000TL;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.
199 citations