scholarly journals Experimental Investigation on Drying and Wetting of GMZ Bentonite Using X-Ray Tomography and Volumetric Digital Image Correlation Technique

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Liufeng Chen ◽  
Kang Li ◽  
Diansen Yang
Keyword(s):  
Image Correlation ◽  
Correlation Technique ◽  
Gmz Bentonite ◽  
Swelling Properties ◽  
Full Field ◽  
X Ray ◽  
The Matrix ◽  
Swelling Characteristics ◽  
Swelling Strain ◽  
High Level

To investigate the shrinking and swelling properties of Gao-Miao-Zi (GMZ) bentonite, which has been considered as engineering barriers for high-level radioactive nuclear waste disposal in China, drying and wetting tests were carried out. The microstructure of the material at each hydric state was recorded using X-ray tomography (X-CT). The 3D images of the material were analyzed using digital volume correlation (DVC) technique, and the full-field strains at mesoscale (i.e., in the order of clay aggregate) during drying and wetting were quantified. The results show that the GMZ bentonite exhibits notable swelling characteristics during wetting and the swelling strain of the material is up to 8% at mesoscale. The full-field strain in 3D of the material is heterogeneous, anisotropic, and irreversible during drying and wetting. The corresponding deformation mechanisms are discussed. Two different swelling mechanisms were also identified: traction occurs in the interface between the matrix and inclusions during swelling; pre-existing fissure closes during swelling.

scholarly journals Identification of the Mechanical Properties of Superconducting Windings Using the Virtual Fields Method

2010 ◽  
Vol 24-25 ◽  
pp. 379-384
Author(s):  
J.H. Kim ◽  
F. Nunio ◽  
Fabrice Pierron ◽  
P. Vedrine
Keyword(s):  
Least Square Method ◽  
Numerical Differentiation ◽  
Tensile Tests ◽  
Least Square ◽  
Image Correlation ◽  
Stereo Image ◽  
Correlation Technique ◽  
Virtual Fields Method ◽  
Displacement Fields ◽  
Full Field

Tensile tests were performed in order to identify the stiffness components of superconducting windings in the shape of rings (also called ‘double pancakes’). The stereo image correlation technique was used for full-field displacement measurements. The strain components were then obtained from the measured displacement fields by numerical differentiation. Because differentiation is very sensitive to spatial noise, the displacement maps were fitted by polynomials before differentiation using a linear least-square method. Then, in the orthotropy basis, the four in-plane stiffnesses of the double pancake were determined using the Virtual Fields Method.

Mineralogical, physical and chemical investigation of compacted Kunigel V1 bentonite in contact with a steel heater in the ABM test package 1 experiment, Äspö laboratory, Sweden

Clay Minerals ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 127-141 ◽  
Author(s):  
H. Sasamoto ◽  
T. Isogai ◽  
H. Kikuchi ◽  
H. Satoh ◽  
D. Svensson
Keyword(s):  
Exchange Capacity ◽  
Exchangeable Cations ◽  
Exchangeable Cation ◽  
Exchange Reactions ◽  
Swelling Properties ◽  
X Ray ◽  
Set Up ◽  
The Stability ◽  
High Level ◽  
Physical And Chemical

AbstractIn many countries, compacted bentonite is a candidate engineering barrier material for safe disposal of high-level radioactive waste. The Swedish Nuclear Fuel and Waste Management Company (SKB) set up an in situ experiment (the ABM project) to compare the stability of different bentonites under the conditions of exposure to an iron source and to elevated temperature (up to 130°C) at the Äspö Hard Rock Laboratory, Sweden. Results for the Japanese bentonite (Kunigel V1) are summarized in the present study.Mineralogical investigation using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) suggested no transformation of smectite or neoformed clay phases. However, a distinct change in exchangeable cations of smectite was indicated (i.e. from Na type to Fe type and/or Ca type) in the bentonite in the vicinity of the steel heater.Measurements of hydraulic conductivity and swelling properties suggest that no significant changes occurred in the bentonite even in the vicinity of the steel heater. This is attributed to the limited portion of the bentonite affected by the iron–bentonite interactions and the incomplete ion-exchange reactions. The methylene blue cation exchange capacity and the determination of the exchangeable cations showed that the lateral distribution for these parameters was constant. However, the total exchangeable cation population has changed significantly compared to the initial sample.

Characterization of LIGA Microsystems Using Digital Image Correlation Technique and SEM Imaging

Aerospace ◽  
2005 ◽  
Author(s):  
Helena (Huiqing) Jin ◽  
Wei-Yang Lu ◽  
Jeff Chames ◽  
Nancy Yang
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Speckle Pattern ◽  
Image Correlation ◽  
Specimen Surface ◽  
Correlation Technique ◽  
Sem Images ◽  
Full Field ◽  
Speckle Patterns ◽  
Dic Technique

A new experimental technique was developed to characterize the mechanical properties of LIGA (an acronym from German words for lithography, electroplating, and molding) materials. An advanced imaging capability, scanning electron microscopy (SEM), with an integrated loading stage allows the acquisition of in situ microstructural images at the micro scale during loading. The load is measured directly from a load cell, and the displacement field is calculated from the SEM images based on the digital image correlation (DIC) technique. The DIC technique is a full-field deformation measurement technique which obtains displacement fields by comparing random speckle patterns on the specimen surface before and after deformation. The random speckle patterns are typically generated by applying a thin layer of material with high contrast to a specimen surface. Alternatively, DIC can also be applied using the microstructural features of a surface as texture patterns for correlation. DIC technique is ideally suited to characterize the deformation field of MEMS structures without the need to generate a random speckle pattern, which can be very challenging on the micro and nanoscale. In this paper, the technique is experimentally demonstrated on a LIGA specimen. The digital images showing LIGA surface features acquired during the loading can serve as random patterns for the DIC method. Therefore, full-field displacement and strain can be obtained directly on the specimen and the errors incurred by the testing system can be eliminated.

scholarly journals Measurement of Complementary Strain Fields at the Grain Scale

2014 ◽  
Vol 996 ◽  
pp. 64-69 ◽  
Author(s):  
Wang Chow ◽  
Denis Solas ◽  
Guillaume Puel ◽  
Eric Perrin ◽  
Thierry Baudin ◽  
...  
Keyword(s):  
Mechanical Test ◽  
Image Correlation ◽  
Correlation Technique ◽  
Al Alloy ◽  
X Ray Diffraction ◽  
Digital Image Correlation Technique ◽  
Strain Fields ◽  
X Ray ◽  
Element Simulation ◽  
Complementary Strain

In this study, a monotonous mechanical test is performed on a sample in Al-alloy containing about twenty-five grains. During this test, both the total and elastic intragranular strain fields are measured at the same time. The former field is observed by digital image correlation technique while the latter one is measured by X-ray diffraction. The strain fields obtained are then dedicated to identify the parameters of a crystalline constitutive model, using finite element simulation.

scholarly journals Analysis of Nonlinear Shear Deformations in CFRP and GFRP Textile Laminates

2011 ◽  
Vol 70 ◽  
pp. 363-368 ◽  
Author(s):  
Himayat Ullah ◽  
Andy R. Harland ◽  
Robert Blenkinsopp ◽  
Tim Lucas ◽  
Dan Price ◽  
...  
Keyword(s):  
Deformation Behaviour ◽  
Production Costs ◽  
Image Correlation ◽  
Woven Composites ◽  
Correlation Technique ◽  
Shear Deformations ◽  
Full Field ◽  
Damage Initiation ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

Carbon fibre-reinforced polymer (CFRP) and glass fibre-reinforced polymer (GFRP) woven composites are widely used in aerospace, automotive and construction components and structures thanks to their lower production costs, higher delamination and impact strengths. They can also be used in various products in sports industry. These products are exposed to different in-service conditions such as large tensile and bending deformations. Composite materials, especially ±45° symmetric laminates subjected to tensile loads, exhibit significant material as well as geometric non-linearity before damage initiation, particularly with respect to shear deformations. Such a nonlinear response needs adequate means of analysis and investigation, the major tools being experimental tests and numerical simulations. This research deals with modelling the nonlinear deformation behaviour of CFRP and GFRP woven laminates subjected to in-plane tensile loads. The mechanical behaviour of woven laminates is modelled using nonlinear elasto-plastic as well as material models for fabrics in commercial finite-element code Abaqus. A series of tensile tests is carried out to obtain an in-plane full-field strain response of [+45/-45]2s CFRP and GFRP laminates using digital image correlation technique according to ASTM D3518/D3518M-94. The obtained results of simulations are in good agreement with experimental data.

Error Estimations in Digital Image Correlation Technique

2007 ◽  
Vol 7-8 ◽  
pp. 265-270 ◽  
Author(s):  
Thorsten Siebert ◽  
Thomas Becker ◽  
Karsten Spiltthof ◽  
Isabell Neumann ◽  
Rene Krupka
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Image Correlation ◽  
Field Analysis ◽  
Correlation Technique ◽  
Full Field ◽  
Wide Range ◽  
The Impact

The reliability for each measurement technique depends on the knowledge of it’s uncertainty and the sources of errors of the results. Among the different techniques for optical measurement techniques for full field analysis of displacements and strains, digital image correlation (DIC) has been proven to be very flexible, robust and easy to use, covering a wide range of different applications. Nevertheless the measurement results are influenced by statistical and systematical errors. We discuss a 3D digital image correlation system which provides online error information and the propagation of errors through the calculation chain to the resulting contours, displacement and strains. Performance tests for studying the impact of calibration errors on the resulting data are shown for static and dynamic applications.

Numerical and Experimental Analysis of Crack Closure

2008 ◽  
Vol 385-387 ◽  
pp. 369-372 ◽  
Author(s):  
Pablo Lopez-Crespo ◽  
Daniel Camas ◽  
Antonio González-Herrera ◽  
J.R. Yates ◽  
Eann A Patterson ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Closure ◽  
Plane Stress ◽  
Image Correlation ◽  
Correlation Technique ◽  
Metallic Materials ◽  
Full Field ◽  
Surface Level ◽  
Stress Models ◽  
Distribution Of Stresses

The fatigue life of metallic materials is strongly influenced by crack closure effects. Finite element (FE) methods allow the study of crack closure with great detail and can provide valuable information about phenomena occurring in the bulk of the material. In this work the distribution of stresses through the thickness of a cracked specimen has been studied using 3D FE simulations. It was found that the transition between the interior of the specimen (plane strain) and the surface (plane stress) differs from that predicted by 2D plane stress models. In addition, an attempt is presented to experimentally validate the results at the surface level. For this purpose full-field image correlation technique was utilized. This allowed direct comparison between the displacement field predicted by the numerical simulations and the experimental results measured by digital image correlation.

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