Ahmet Cevahir Çınar · 2019
Analysis that requires human judgement can add bias which may, as a result, increase uncertainty. Accurate detection of a crack and segmentation of the crack geometry is beneficial to any fracture experiment. Studies of crack behaviour, such as the effect of closure, residual stress in fatigue or elastic-plastic fracture mechanics, require data on crack opening displacement. Furthermore, the crack path can give critical information of how the crack interacts with the microstructure and stress fields. Digital Image Correlation (DIC) and Digital Volume Correlation (DVC) have been widely accepted and routinely used to measure full-field displacements in many areas of solid mechanics, including fracture mechanics. However, current practise for the extraction of crack parameters from displacement fields usually requires manual methods and are quite onerous, particularly for large amounts of data.
This thesis introduces the novel application of Phase Congruency-based Crack Detection (PC-CD) to automatically detect and characterise cracks from displacement fields.
Phase congruency is a powerful mathematical tool that highlights a discontinuity more efficiently than gradient based methods. Phase congruency’s invariance to the magnitude of the discontinuity and its state-of-the-art de-noising method, make it ideal for the application to crack tip displacement fields. PC-CD’s accuracy is quantified and benchmarked using both theoretical and virtual displacement fields. The accuracy of PC-CD is evaluated and compared with conventional, manual computation methods such as Heaviside function fitting and gradient based methods. It is demonstrated how PC-CD can be coupled with a new method that is based on the conjoint use of displacement fields and finite element analysis to extract the strain energy release rate of cracks automatically. The PC-CD method is extended to volume displacement fields (VPC-CD) and semi-autonomously extracts crack surface, crack front and opening displacement through the thickness. As a proof of concept, PC-CD and VPC-CD are applied to a range of fracture experiments varying in material and fracture behaviour: two ductile and one quasi-brittle for surface displacement measurements; and two quasi-brittle and one ductile for volume measurements. Using the novel PC-CD and VPC-CD analyses, the crack geometry is obtained fully automatically and without any user judgement or intervention. The geometrical parameters extracted by PC-CD and VPC-CD are validated experimentally through other tools such as: optical microscope measurements, high resolution fractography and visual inspection.
Cited by 0
Magued Iskander · Springer series in geomechanics and geoengineering · 2010
Cited by 38
Chao Li · DR-NTU (Nanyang Technological University) · 2010
In this work, software is designed to realize several commonly used algorithms in Two-dimensional digital image correlation (2D DIC). \nMethodologies of 2D DIC technique for displacement measurement and strain field estimation are provide with lot of details and the student’s understanding. \nSoftware design procedures and details are provided from user interface set up to each 2D DIC method with measurement results, problem analyzes and discussions. \nThis software is written in JAVA with Net beans. The simulation results have shown that the designed has fulfilled the requirement.
Cited by 0
Paul W. Wiseman · Methods in enzymology on CD-ROM/Methods in enzymology · 2012
Cited by 35
Shih‐Yen Lin · DR-NTU (Nanyang Technological University) · 2014
As a new and low-cost optical measurement technique to study the displacement and strain distribution on the surface of a planner specimen with high precision, twodimension digital image correlation (2D DIC) is now widely accepted and applied in many areas of picture or image processing. This process, also known as template matching, is used to locate an object in a picture or match pieces of two images to one another in image registration. The 2D DIC technique is an optical method that uses a mathematical correlation analysis to examine digital image data taken. This technique consists of two main steps: consecutive images capturing during the deformation period and analyse the behaviour of the specimen while is subject to incremental loads. In this report, the methodology of implementing the 2D DIC that used in the project is reviewed and discussed. Detailed accuracy measurement and results analysis are provided. Proposals and suggestions for achieving a better accuracy measurement and further improvement are also recommended. The results of this project show a great application potential of the 2D DIC technique for various situations. Based on the simple surface preparation and the ability to acquire displacement/strain measurements over a large range of deformation, 2D DIC should serve as a valuable tool for varieties of researches and applications.
Cited by 0
Bing Pang · 2022
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Eric Badiqué, Yasuhiro Komiya, Nagaaki Ohyama et al. · Optics Communications · 1987
Cited by 34
Ivan Jandejsek · Digital Repository (National Repository of Grey Literature) · 2007
This paper presents the optical Digital Image Correlation method for in plane displacement field measurements. This method is based on tracing random structures, which are defined either by a sprayed pattern or by its own specimen surface structure. The displacements fields are obtained by measuring the mutual displacements of structure traced templates. The methodology for sub-pixel displacement measurements is presented.
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Tokumaru, P. T., Dimotakis, P. E. · Caltech Library · 1993
This paper focuses on the correlation of two successive scalar images for the purpose of measuring imaged fluid motions. A method is presented for deforming, or transforming, one image to another. Taylor series expansions of the Lagrangian displacement field are used, in conjunction with an integral form of the equations of motion, to approximate this transformation. The proposed method locally correlates images for displacements, rotations, deformations, and higher order displacement gradient fields, and applies a global minimization procedure to insure a global consistency in the results. An integral form of the equations of motion is employed and, as a consequence, no explicit spatial or temporal differentiation of the image data is required in estimating the displacement field. As a consequence, this method is appropriate for both continuous scalar as well as discrete particle image data. Successive two-dimensional digital CCD images of fluid motion marked with dye, are used to verify the capabilities of the method. The utility of the method is also illustrated using a pair of Voyager 2 images of Jupiter.
Cited by 0Open access
?????????, ?????????, ????????? · Scholarworks@UNIST (Ulsan National Institute of Science and Technology) · 2018
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Nicholas McCormick, Jerry Lord · Materials Today · 2010
Strain and displacement are critical parameters within engineering and construction projects. However, measuring these parameters outside of the lab requires a difficult choice between conventional techniques, as accuracy, simplicity and cost must all be balanced. Digital Imaging Correlation (DIC) is a technique which may prove to be ideally suited for the study of crack propagation and material deformation in real-world applications, as it has the potential to become a cheap, simple yet accurate solution. This is the motivation for perfecting the technique for researchers based at the UK's National Physical Laboratory (NPL). NPL is also expanding its use into challenging areas, such as enabling DIC to be used over a period of time without the need for a permanent set up, or in hard-to-reach areas via small unmanned helicopters carrying camera and relocation equipment.
Cited by 417Open access
Marko Šitum · University of Split Repository · 2023
Analiziranjem programa MATLAB bilo je potrebno prikazati njegovu primjenu kod polja deformacija i polja pomaka koristeći MATLAB-ov alat zvan Ncorr. S obziron na mogućnost snimanja modela i brađivanja videozapisa kroz programe za uređivanje videozapisa, uspješni su izlazni rezultati završnog rada. Radi odličnih uvjeta rada u laboratoriju smo dobili vrlo precizne rezultate bez velikih greški.
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Goh, Si Yi. · DR-NTU (Nanyang Technological University) · 2013
Two-dimensional Digital Image Correlation (2D DIC) is a practical and effective tool for qualitative in-plane deformation measurement of a planar surface object. It is widely accepted in the field of experimental mechanics. In this project, software is designed to realize commonly used algorithms in Two-dimensional digital image correlation (2D DIC). \n \n \n \n \n \n \n \nThe purpose of this project is to investigate the commonly used methods in 2D DIC. Hence, methodologies of 2D DIC techniques for displacement measurement are provided in detail and to the scope of the author’s understanding. The techniques include the usage of normalized cross correlation to find the pixel level displacement and the use of bi-cubic interpolation to find the sub-pixel displacement of the pixels. \n \n \n \n \n \n \n \nThis report will also cover the software design procedure and details from the user interface and the 2D DIC methods implemented with the results, analysis and discussions. The backbone of this project is built based on several mathematical equations which will be shared in chapter 2 and 3. The final product of this project is made into an executable program which can be executed in DOS environment. \n \n \n \n \n \n \n \nThe results of this project can be seen from the screenshots posted in the report as well. \n \n \n \n \n \n \n \nFor future work, the author suggests that different programming languages can be used in the making of 2D DIC software as MATLAB® is limited in the user interface as compared to other languages, such as Java™. However, MATLAB® is very useful in the development of the backend of this 2D DIC software. \n \n \n \n \n \n \n \nThe final product of this project is created as a standalone application which can be run on UNIX systems and Microsoft Windows. The application includes the pixel and sub-pixel analysis which will be discussed in detail in the report.
Cited by 0
Ho, Yenn Jie. · DR-NTU (Nanyang Technological University) · 2013
Digital Image Correlation (DIC) is an optical method that utilizes tracking and image registration techniques for accurate measurement of changes in digital images. Over the last two decades, developments in DIC have enabled it to become a practical and effective tool for in-plane deformation and strain measurements of a planar object surface. \n \nBy comparing images of a test object surface acquired before and after deformation, DIC provides the full-field displacement of the surface. Through various sub-pixel displacement registration algorithms such as the Newton-Raphson method, DIC can measure displacement up to sub-pixel accuracy. \n \nThis report investigates and gives comparison on the integer pixel and some of the sub-pixel displacement registration techniques commonly used in DIC.
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Wahono, Natalinus Albion · DR-NTU (Nanyang Technological University) · 2012
In the process of finding similarities between one images and other image, template matching algorithms which give good precision result has been researched largely. Various template matching algorithms have been researched and available to be used for the digital image correlation processing and DIC (digital image processing) is an advance process in this area. Here, high performance software is developed which can be used to find displacement between surfaces before and after deformation as one application of DIC. In this project high performance software is developed which is used to find displacement between surfaces before and after deformation as one application of DIC. To achieve this objective, the author used some literatures on DIC to modify a DIC algorithms and techniques comparison software implemented by Anjar in [1]. This modification is done in the three aspects: user interface, software design, and algorithm. The resulted software called "Image Analyzer" showed that improvement on those aspects can improve performance in term of calculation cost and other software qualitative parameters such as maintainability, adaptability, and ease of use. The advancement of "Image Analyzer could be improved by integrating many other applications and features in
Cited by 0
Anthony Wilson, Bianca C. Chin, Vivian Hsu et al. · Plastic & Reconstructive Surgery · 2015
Diagnostic, II.
Cited by 24
Michel Bornert, François Hild, Jean‐José Orteu et al. · 2012
Chapter 6
Cited by 118
Tokumaru, P. T., Dimotakis, P. E. · Caltech Library · 1992
This paper focuses on the correlation of two successive scalar images for the purpose of measuring imaged fluid motions. A method is presented for deforming, or transforming, one image to another. Taylor series expansions of the Lagrangian displacement field are used, in conjunction with an integral form of the equations of motion, to approximate this transformation. The proposed method locally correlates images for displacements, rotations, deformations, and higher order displacement gradient fields, and applies a global minimization procedure to insure a global consistency in the results. An integral form of the equations of motion is employed and, as a consequence, no spatial or temporal differentiation of the image data is required in estimating the displacement field. Successive two-dimensional digital CCD images of fluid motion marked with dye, are used to verify the capabilities of the method. The utility of the method is also illustrated using a pair of Voyager 2 images of Jupiter.
Cited by 0Open access
Chambers, David · CERN Document Server (European Organization for Nuclear Research) · 2017
Cited by 0
Paul W. Wiseman, Jeffrey A. Squier, Mark H. Ellisman et al. · Journal of Microscopy · 2000
We introduce two-photon image correlation spectroscopy (ICS) using a video rate capable multiphoton microscope. We demonstrate how video rate two-photon microscopic imaging and image correlation analysis may be combined to measure molecular transport properties over ranges typical of biomolecules in membrane environments. Using two-photon ICS, we measured diffusion coefficients as large as 10(-8) cm2 s(-1) that matched theoretical predictions for samples of fluorescent microspheres suspended in aqueous sucrose solutions. We also show the sensitivity of the method for measuring microscopic flow using analogous test samples. We demonstrate explicitly the advantages of the image correlation approach for measurement of correlation functions with high signal-to-noise in relatively short time periods and discuss situations when these methods represent improvements over non-imaging fluorescence correlation spectroscopy. We present the first demonstration of two-photon image cross-correlation spectroscopy where we simultaneously excite (via two-photon absorption) non-identical fluorophores with a single pulsed laser. We also demonstrate cellular application of two-photon ICS for measurements of slow diffusion of green fluorescent protein/adhesion receptor constructs within the basal membrane of live CHO fibroblast cells.
Cited by 174Open access