DIC Challenge: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses

Reu, Phillip L.; Toussaint, Evelyne; Jones, Elizabeth M. C.; Bruck, Hugh A.; Iadicola, Mark A.; Balcaen, Ruben; Turner, David A.; Siebert, Thorsten; Lava, Pascal; Simonsen, Micah

doi:10.1007/s11340-017-0349-0

Cited by 122 publications

(79 citation statements)

References 30 publications

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“…Thus the method may be used for assessment of improvements in a DIC measurement when looking for optimum test conditions and parameters, or for comparing DIC measurements with other full-field measurement methods. Comparison to the spatial resolution metric of the DIC Challenge paper [79] shows a good agreement of attenuation of known imposed displacements by the DIC measurement and by convolution with a Gaussian point spread function with kernel size corresponding to the autocorrelation length.…”

Section: Discussionmentioning

confidence: 82%

“…Since the metric of spatial resolution in the DIC Challenge paper [79] is different than the metric proposed in this study, a direct comparison of the obtained spatial resolution values is not generally valid. In addition, the images provided in the DIC Challenge did not include strain variations with sufficiently short wavelengths to really challenge the DIC codes with respect to the detectability of the commanded strain variations.…”

Section: Comparison To Sample 14 Of the Dic Challenge [Paper Iii]mentioning

confidence: 89%

“…The DIC Challenge [79] provides test images for comparing the spatial resolution of different DIC codes. In particular, for Sample 14, sinusoidally varying wavelength in horizontal direction (which results in increasing strain as the wavelength decreases) are imposed on the images.…”

Section: Comparison To Sample 14 Of the Dic Challenge [Paper Iii]mentioning

confidence: 99%

“…It is well established that in a DIC measurement there is a trade-off between the spatial resolution and precision of the measurement, and that the trade-off governs the choice of subset sizes in relation to quality of the pattern when analyzing the DIC measurements. Methods for determining the spatial resolution with the aid of an imposed displacement field with known variations in displacement have been proposed [79]. However, in the absence of an imposed displacement field, quantifying the spatial resolution of a specific measurement, including the combined effects of subset size, calculation methods, aspects of the pattern, and of imaging conditions, is not that straightforward.…”

Section: Dic Noise Level and Spatial Resolution [Paper Iii]mentioning

confidence: 99%

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Hydrogen effects on mechanical performance of nodular cast iron

2019

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The KBS-3 method for long-term disposal of spent nuclear fuel is designed with an external self-standing copper shell, which provides the most important barrier against corrosion and escape of radionuclides, and an internal nodular cast iron insert, which provides the load-bearing structure against external loads. The material intended for the load-bearing insert is ferritic nodular cast iron EN 1563 grade EN-GJS-400-15U. In this paper, hydrogen uptake and sensitivity to hydrogen-induced cracking of the cast iron were studied using tensile testing under continuous electrochemical charging in 1 N H2SO4 solution. Hydrogen uptake was measured by using the thermal desorption method. It was found that the hydrogen desorption profile manifests three distinct peaks at initial locations of 400, 500, and 700 K with a heating rate of 6 K/min. Plastic deformation results in a remarkable increase of the 400 K peak, which indicates hydrogen uptake during deformation. In the constant extension rate tests (CERT) and the constant load tests (CLT), electrochemical hydrogen charging reduced markedly the elongation to fracture and time to fracture, respectively. In CLT, hydrogen charging increased dramatically the creep rate at the applied load of about 0.7 yield stress. Ligaments between the graphite nodules exhibit brittle cleavage facets in the presence of hydrogen, while the ligaments show a characteristic ductile appearance of shear and small dimples when testing in air or distilled water. The obtained results are discussed in terms of the known mechanisms of hydrogen-induced cracking and the role of the graphite nodules in the embrittlement of ductile cast iron.

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Section: Discussionmentioning

confidence: 82%

Section: Comparison To Sample 14 Of the Dic Challenge [Paper Iii]mentioning

confidence: 89%

Section: Comparison To Sample 14 Of the Dic Challenge [Paper Iii]mentioning

confidence: 99%

Section: Dic Noise Level and Spatial Resolution [Paper Iii]mentioning

confidence: 99%

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Hydrogen effects on mechanical performance of nodular cast iron

2019

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“…Recent progress in DIC for surface deformation measurements is comprehensively discussed by Pan et al Special emphasis on the advances in DIC (from the year 2010) on topics such as speckle pattern fabrication and quality assessment, 2D‐DIC imaging system, subset‐based correlation algorithm, and FE‐based correlation algorithm are summarized in detail. To verify and validate 2D‐DIC codes (commercial as well as academic), description of sample images available as part of 2D‐DIC challenge are discussed elaborately by Reu et al…”

Section: Introductionmentioning

confidence: 99%

High‐speed, two‐dimensional digital image correlation algorithm using heterogeneous (CPU‐GPU) framework

Thiagu

Subramanian²,

Nasre

2020

Strain

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Two-dimensional digital image correlation (2D-DIC) is an experimental technique used to measure in-plane displacement of a test specimen. Real-time measurement of full-field displacement data is challenging due to enormous computational load of the algorithm. In order to improve the computational speed, the focus of recent research works has been on the approach of parallelization across subsets within image pairs using graphics processing unit (GPU). But alternate GPU-based parallelization approaches to improve the performance of this algorithm as per the order of data processing have not been explored.To address this research gap, our method utilizes parallelism within a subset as well as across subsets for each computation step in an iteration cycle. A heterogeneous (CPU-GPU) framework in combination with a pyramid-based initial values estimation for subsets (in parallel) is proposed in this work. The precompute steps of the proposed framework are implemented using CPU, whereas the main iterative steps are realized using GPU. It is demonstrated that the overall computational speed of the proposed heterogeneous framework improves by ≈ 9× compared to a sequential CPU-based implementation for a pair of gray-scale images with a resolution of 588 × 2, 048 pixels. As an important milestone, feasibility to measure deformations in real time (≤1 s) is manifested in this study.

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Physical simulation of upper protective coal layer mining with different coal seam inclinations

Fang

Shu

Wang

2020

Energy Science & Engineering

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Protective coal layer (PCL) mining is a preferred regional method for preventing coal and gas outbursts; stress‐relief of PCL mining is the prerequisite of pressure‐relief gas drainage. In order to study the stress‐relief effect of PCL mining on protected coal seams and determine the protection scope of PCL mining under different inclinations, this paper uses physical simulations to study the stress‐relief law and deformation characteristics of the strata during upper PCL mining with a gentle inclination (25°), an intermediate inclination (45°), and a steep inclination (65°). The results show that as the coal seam dip increases, the degree of deformation and failure of the overburden strata gradually decreases, the severe subsidence and expansion area of the overburden strata tends to gradually develop in the uphill direction of the working face, and the floor strata underlying the protective seam significantly expand toward the goaf. However, the absolute value of the upward movement of the floor strata is much smaller than that of the roof strata; and the greater the dip angle, the greater the ratio of floor displacement to roof subsidence. The stress‐relief curve of the protected layer is approximately U‐shaped. As the inclination of the coal seam increases, the stress‐relief range decreases gradually. The maximum relief‐stress and the stress release coefficient of the protected layer initially increase and then decrease. The stress concentration coefficient of the protected coal seam initially increases first and then decreases in both uphill and downhill of the working face in the PCL. As the inclination increases, the stress‐relief angle of the downhill boundary initially increases and then decreases, while the stress‐relief angle of the uphill boundary decreases gradually. Our research results provide guidance for the delimitation of the protected scope of PCLs with different dip angles.

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DIC Challenge: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses

Cited by 122 publications

References 30 publications

Hydrogen effects on mechanical performance of nodular cast iron

Hydrogen effects on mechanical performance of nodular cast iron

High‐speed, two‐dimensional digital image correlation algorithm using heterogeneous (CPU‐GPU) framework

Physical simulation of upper protective coal layer mining with different coal seam inclinations

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