Numerical-experimental hybrid method for stress separation in digital gradient sensing method

Zhang, Rui; Guo, Ran; Hu, Cheng

doi:10.1016/j.optlaseng.2014.08.017

Cited by 5 publications

(3 citation statements)

References 22 publications

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“…In our previous study, we found that the angular deflection associated with the rigid body motion is much larger than that caused by stress concentration. To remove the influence of the rigid body translation and rotation in that special problem in [2,3], we impose the boundary conditions of the problem to quantify the contour levels of the analysis. That is, in this problem, the boundary conditions such as asymmetric stress gradients (ϕ y ) in the y direction about the x axis, symmetric stress gradients (ϕ x ) in the x direction about the x axis, and vanishing stress gradients far away from the loading point are all utilized.…”

Section: Measurement Science and Technologymentioning

confidence: 99%

“…The method can link angular deflections of light rays quantified using DIC to two orthogonal stress gradients under plane stress, so DGS. In recent years, this noncontact, DICbased optical technique has undergone significant improvements in technique [2][3][4] as well as a number of engineering applications [5][6][7]. A numerical-experimental approach was proposed for stress separation in the digital gradient sensing (DGS) method [2,3].…”

Section: Introductionmentioning

confidence: 99%

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Evaluating angular deflections from the digital gradient sensing method with rigid-motion deleted

Zhang

2016

Meas. Sci. Technol.

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The digital gradient sensing method is used for measuring small angular deflections of light rays due to local stresses in transparent planar solids. The method is based on two-dimensional (2D) digital image correlation (DIC) to measure the angular deflection of light rays; however, when a specimen is subjected to loading, deformation measurement from DIC is not perfect because of the existence of small in-plane and out-of-plane motions of the test sample surface that occurred after loading. These disadvantages will lead to errors in the measured angular deflections. The influence of unavoidable in-plane and out-of-plane motions was discussed, and a method to eliminate the influence to show the pure stress gradient of polymethy methacrylate is demonstrated.

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Section: Measurement Science and Technologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluating angular deflections from the digital gradient sensing method with rigid-motion deleted

Zhang

2016

Meas. Sci. Technol.

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“…DGS can be classified as transmission-mode DGS (t-DGS) and reflection-mode DGS (r-DGS), where the former one measures non-uniform stress distribution induced angular deflections to characterize stress gradient fields of transparent materials, while the later one measures angular deflections reflected off an optically reflective surface to estimate the surface slopes of specular structures [ 1 , 2 ]. Due to its advantages of simple implementation, high accuracy, and high computational efficiency [ 3 , 4 , 5 ], DGS has been successfully applied in many fields—e.g., material testing, fracture mechanics, impact dynamics, and high-temperature characterizations—showing great potential in recent studies [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Digital Gradient Sensing Using Backlight Digital Speckle Target

Dong

et al. 2020

Sensors

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Digital gradient sensing (DGS) is a non-contact and full-field optical measurement technique, which assesses mechanical behaviors of transparent materials or specular structures by measuring angular deflections of light rays. However, owing to the poor light-gathering capability of its imaging system, the dynamic performance of DGS is heavily restricted. Here, a method of enhancing the dynamic performance of DGS by improving its speckle target is proposed. The method employs the technique of backlight illumination, which significantly increases the utilization efficiency of light, shortens the exposure time, and enhances the dynamic performance of DGS. Additionally, it also uses the optimized digital speckle pattern to improve the measurement precision and accuracy. For validation, a comparison experiment was conducted, proving that the proposed method can improve the utilization efficiency of light by about 80 times and improve the quality of the speckle images by about 40%. Real tests, including a uniaxial tension test using transmission-mode DGS (t-DGS) and a three-point bending test using reflection-mode DGS (r-DGS), were also carried out, showing the efficacy and high compatibility of the proposed backlight digital speckle target. In summary, this simple method greatly improves the performance of DGS, which can be used as a standard method in both t-DGS and r-DGS.

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A generalized DGS method for studying the deformation field around a crack tip

Zhang

Guo

2016

Optics and Lasers in Engineering

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Numerical-experimental hybrid method for stress separation in digital gradient sensing method

Cited by 5 publications

References 22 publications

Evaluating angular deflections from the digital gradient sensing method with rigid-motion deleted

Evaluating angular deflections from the digital gradient sensing method with rigid-motion deleted

Enhanced Digital Gradient Sensing Using Backlight Digital Speckle Target

A generalized DGS method for studying the deformation field around a crack tip

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