Whole field evaluation of stress components in digital photoelasticity—Issues, implementation and application

Ramji, M.; Ramesh, K.

doi:10.1016/j.optlaseng.2007.09.006

Cited by 86 publications

(45 citation statements)

References 39 publications

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“…(20). The isoclinic value is unwrapped in the range À π/2 to þπ/2 using the adaptive quality-guided phase unwrapping algorithm described in [88]. The retardation is determined by the RGB method using Eq.…”

Section: Birefringent Coatingsmentioning

confidence: 99%

“…(14), that includes the condition of continuity of the retardation, and a calibration procedure that considers the differences between the colours in the measure sample and the calibration sample [64]. The total fringe order obtained is smoothed using an algorithm described in [88] to improve results. The technique is applied to various cases of industrial interest.…”

Section: Birefringent Coatingsmentioning

confidence: 99%

See 1 more Smart Citation

Review of RGB photoelasticity

Ajovalasit

Petrucci

Scafidi

2015

Optics and Lasers in Engineering

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Section: Birefringent Coatingsmentioning

confidence: 99%

Section: Birefringent Coatingsmentioning

confidence: 99%

Review of RGB photoelasticity

Ajovalasit

Petrucci

Scafidi

2015

Optics and Lasers in Engineering

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“…Once obtained the value of  and  unwrapping, applies digital implementation of the shear difference technique for whole field stress separation of 2-D problems of any geometry shown in [15][16][17]. Thus, it calculates the values of the phase maps, principal tensions ( 1 ,  2 ) and normal ( x ,  y ) and shear ( xy ) stresses.…”

Section: Before Unwrapping Change To [- ]mentioning

confidence: 99%

Separation of Isochromatics and Isoclinics Phasemaps for the Photoelastic Technique with use Phase Shifting and a Large Number of High Precision Images

Magalhães¹,

Neto²,

Júnior³

et al. 2013

Metrology and Measurement Systems

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Digital photoelasticity is an important optical metrology follow-up for stress and strain analysis using full-field digital photographic images. Advances in digital image processing, data acquisition, procedures for pattern recognition and storage capacity enable the use of the computer-aided technique in automation and facilitate improvement of the digital photoelastic technique. The objective of this research is to find new equations for a novel phase-shifting method in digital photoelasticity. Some innovations are proposed. In terms of phaseshifting, only the analyzer is rotated, and the other equations are deduced by applying a new numerical technique instead of the usual algebraic techniques. This approach can be used to calculate a larger sequence of images. Each image represents a pattern and a measurement of the stresses present in the object. A decrease in the mean errors was obtained by increasing the number of observations. A reduction in the difference between the theoretical and experimental values of stresses was obtained by increasing the number of images in the equations for calculating phase. Every photographic image has errors and random noise, but the uncertainties due to these effects can be reduced with a larger number of observations. The proposed method with many images and high accuracy is a good alternative to the photoelastic techniques.

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“…In order to unwrap the isoclinic phase map, researchers [12][13][14][15][16] reported several methods to make the continuous isoclinic phase map in the true phase interval. Siegmann et al [12] proposed a robust unwrapping approach that was based on processing areas or regions rather than pixels, but the process for choosing the initial area for unwrapping was not clearly described.…”

Section: Introductionmentioning

confidence: 99%

“…Pinit and Umezaki [13] introduced an isoclinic phase unwrapping algorithm to account for isotropic points, the presence of isotropic points is initially detected by a cumbersome procedure and then unwrapping is done. Ramji and Ramesh [14] developed a quality guided approach for isoclinic unwrapping and by the phase map smoothing algorithm [8,15,16] phase map unwrapping method guided by morphological techniques is introduced. The motivation of this work is to produce an algorithm to resolve the ambiguity in isoclinic phase map that use a simple approach but retains the correctly demodulated regions of the isoclinic phase map.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Morphology Guided Automatic Unwrapping Isoclinic Phase Map in White Light Photoelasticity

Liu¹,

Dai²

2015

Journal of the Optical Society of Korea

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By comparing the results calculated by atan() and atan2() functions, the correctly estimated region of isoclinic phase map is determined using morphological techniques. The isoclinic phase map is automatically unwrapped in the true phase range -π /2 to π /2. Demonstrations of the method on a disc and a ring under diametral compression are performed. Test results compare well with the theoretical results. Furthermore, the influences of principal stress direction and the range of isoclinic phase upon stress separation are discussed.

show abstract

Whole field evaluation of stress components in digital photoelasticity—Issues, implementation and application

Cited by 86 publications

References 39 publications

Review of RGB photoelasticity

Review of RGB photoelasticity

Separation of Isochromatics and Isoclinics Phasemaps for the Photoelastic Technique with use Phase Shifting and a Large Number of High Precision Images

Mathematical Morphology Guided Automatic Unwrapping Isoclinic Phase Map in White Light Photoelasticity

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