Computational reduction of the image sets required in conventional phase shifting methods applied to digital photoelasticity

2017 ◽  
Author(s):  
Juan Carlos Briñez de León ◽  
Alejandro Restrepo Martínez ◽  
John W. Branch Bedoya
Keyword(s):  
Phase Shifting ◽  
Digital Photoelasticity ◽  
Computational Reduction

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

2013 ◽  
Vol 20 (1) ◽  
pp. 127-138 ◽  
Author(s):  
Cristina Almeida Magalhães ◽  
Perrin Smith Neto ◽  
Pedro Américo Almeida Magalhães Júnior ◽  
Clovis Sperb de Barcellos
Keyword(s):  
Numerical Technique ◽  
Random Noise ◽  
Strain Analysis ◽  
Good Alternative ◽  
Phase Shifting ◽  
Full Field ◽  
Object A ◽  
Digital Photoelasticity ◽  
The Difference ◽  
Experimental Values

Abstract 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.

A New Six-Step Phase Shifting Technique Using Mixed-Polariscope in Digital Photoelasticity

2006 ◽  
Vol 326-328 ◽  
pp. 35-38 ◽  
Author(s):  
Manoharan Ramji ◽  
K. Ramesh
Keyword(s):  
Low Cost ◽  
Monochromatic Light ◽  
Strain Analysis ◽  
Phase Shifting ◽  
Stress And Strain ◽  
Photoelastic Method ◽  
Full Field ◽  
Separate Branch ◽  
Quarter Wave ◽  
Digital Photoelasticity

Photoelasticity is one of the most widely used techniques for experimental stress and strain analysis. With the availability of low cost digital image processing systems, a separate branch of photoelasticity known as digital photoelasticity came into existence providing whole-field values of the isoclinics (θ) and isochromatics (N) in a true sense. Among the several methods available for data acquisition, phase shifting / polarization stepping techniques are most widely used for their simplicity and accuracy. In this paper a new digital photoelastic method based on phase shifting using monochromatic light source is presented. It provides full field values of θ and N. The arrangement is carefully chosen with the intention of reducing the influence of quarter wave mismatch error in the evaluation of θ and N. The methodology is validated for the benchmark problem of a disk under diametral compression.

Computational hybrid phase shifting technique applied to digital photoelasticity

Optik ◽  
2018 ◽  
Vol 157 ◽  
pp. 287-297 ◽  
Author(s):  
Juan Carlos Briñez ◽  
Alejandro Restrepo Martínez ◽  
John W. Branch
Keyword(s):  
Phase Shifting ◽  
Phase Shifting Technique ◽  
Digital Photoelasticity

scholarly journals Effect of the Reinforce Process on the Fatigue Fracture Properties of Aeronautical Polymethyl Methacrylate

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Wei Shang ◽  
Xiao-jing Yang ◽  
Xin-hua Ji ◽  
Zhong-xian Liu
Keyword(s):  
Mechanical Properties ◽  
Polymethyl Methacrylate ◽  
Fatigue Fracture ◽  
Fatigue Cracks ◽  
Experimental Results ◽  
Phase Shifting ◽  
Fracture Properties ◽  
Phase Shifting Technique ◽  
Digital Photoelasticity

The main purpose of the present work is to investigate fatigue fracture mechanical properties of aeronautical directional polymethyl methacrylate (PMMA) which has been treated by the directional tensile technology. Firstly, the fatigue cracks growth has been tracked in directional PMMA using the stroboscopic method. Then, the digital photoelasticity with a phase-shifting technique was used to measure the uniformity of the interlaminar stretching. Based on obtained experimental results, the effect of the directional stretching on fatigue fracture properties of PMMA was analyzed. Finally, fatigue fracture properties of laminated directional PMMA were discussed and compared with those of monolayer directional PMMA. Results of this work show that the lamination technology can strengthen the interlayer of directional PMMA and enhance its fatigue fracture properties.

Numerical methods of phase shifting to stress measurement with digital photoelasticity using plane polariscope

2017 ◽  
Author(s):  
Filipe Gomes Vieira ◽  
Jordana Simões Ribeiro Martins ◽  
João Marcos Simões Ribeiro ◽  
Marcos Vinícius dos Santos Rocha ◽  
Pedro Américo Almeida Magalhães Júnior ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Stress Measurement ◽  
Phase Shifting ◽  
Digital Photoelasticity

Numerical Methods for the Photoelastic Technique using Phase Shifting

2015 ◽  
Vol 31 (4) ◽  
pp. 355-367
Author(s):  
C. A. Magalhaes ◽  
P. S. Neto ◽  
P. A. A. Magalhaes ◽  
C. S. de Barcellos
Keyword(s):  
Numerical Methods ◽  
Numerical Technique ◽  
Random Noise ◽  
Phase Shifting ◽  
The Other ◽  
Object A ◽  
Digital Photoelasticity ◽  
Phase Shifting Method ◽  
The Difference ◽  
Experimental Values

AbstractThe 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 phase-shifting, 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 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.

Sign in / Sign up

Export Citation Format

Share Document