Inverse identification of tensile and compressive damage properties of graphite material based on a single four-point bending test

Liu, Guangyan; Wang, Lu; Yi, Yanan; Sun, Libin; Shi, Li; Jiang, Han; Ma, Shuping

doi:10.1016/j.jnucmat.2018.07.022

Cited by 17 publications

(7 citation statements)

References 17 publications

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“…The results obtained in this work (e.g. Figure 16a) and by others [20][21][22]72,73 clearly show that this is not the case. It was observed by Awaji and Sato 49 that a correction factor was required to obtain the uniaxial tensile strength from the tensile stress calculated at failure under diametral compression, and that this factor was sensitive to the ratio of tensile to compressive strength of the material.…”

Section: Discussionsupporting

confidence: 39%

“…Valid measurements of the elastic modulus may be accomplished in this geometry by mapping the displacements on the surface with a higher precision than can be achieved by DIC, such as using ESPI (electronic speckle pattern interferometry) 52 . Recently, inverse modelling of DIC analysis of optical observations in flexure and disc compression (with a central hole) has been used to extract the engineering relationship between strain and stress in a fine grained isotropic graphite (IG11) 72,73 That work obtained a non-linear damage relation that was most significant in tension, with a decrease in elastic modulus with increasing strain that was also significantly greater in tension than in compression 72 . The behaviour under biaxial loading was similar to uniaxial loading, with the non-linear damage effect slightly increased 73 .…”

Section: Discussionmentioning

confidence: 99%

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In situ measurement of elastic and total strains during ambient and high temperature deformation of a polygranular graphite

Liu

Zillhardt

Earp

et al. 2020

Carbon

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In situ neutron diffraction and synchrotron X-ray diffraction, combined with image correlation analysis of 2D optical and 3D X-ray tomography datasets, have been used to investigate the relationship between elastic lattice strain and total strain during deformation of Gilsocarbon (IM1-24) polygranular nuclear grade graphite. The specimens were flat-end Brazilian discs under diametral loading, such that a compressive-tensile biaxial stress state was developed in the central region. The X-ray study was at ambient temperature, and the neutron diffraction was conducted at temperatures from ambient to 850°C. When under compression, there is a temperature-insensitive linear relationship between the total strain and the lattice strain that is measured perpendicular to the graphite basal planes. However, when under tensile stress, the total strain and elastic strain relationship is temperature sensitive: below 600°C, the lattice tensile strain saturates with increasing total tensile strain; above 600°C, significantly higher tensile lattice strains are sustained. The saturation in tensile lattice strain is attributed to microcracking in the graphite microstructure. Improved resistance to microcracking and damage tolerance at elevated temperature explains the increase in tensile strength of polygranular graphite.

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Section: Discussionsupporting

confidence: 39%

Section: Discussionmentioning

confidence: 99%

In situ measurement of elastic and total strains during ambient and high temperature deformation of a polygranular graphite

Liu

Zillhardt

Earp

et al. 2020

Carbon

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“…Based on the high-efficiency double iterative inversion method proposed by the authors’ previous work [ 24 ], this paper optimizes its objective function and iterative process. It puts forward the DF-PF inversion method, which can realize the synchronous inversion of rock Young’s modulus field and Poisson’s ratio field, as shown in Figure 1 .…”

Section: Df-pf Inversion Methodsmentioning

confidence: 99%

“…The above inversion methods can obtain the macro Young’s modulus and other material parameters under a certain stress state, which provide ideas for measuring microparameters. Liu et al [ 24 , 25 ] proposed a double iterative inversion method based on DIC and FEM. They obtained Young’s modulus field (i.e., elements micro Young’s modulus distribution on specimen surface) and damage variable field of graphite material.…”

Section: Introductionmentioning

confidence: 99%

Inversion Method of the Young’s Modulus Field and Poisson’s Ratio Field for Rock and Its Test Application

et al. 2022

Self Cite

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As one typical heterogeneous material, the heterogeneity of rock micro parameters has an important effect on its macro mechanical behavior. The study of the heterogeneity of micro parameters is more important to reveal the root cause of deformation and failure. However, as a typical heterogeneous material, the current testing and inversion method is not suitable for micro parameters measurement for the rock. Aiming at obtaining the distribution of micro Young’s modulus and micro Poisson’s ratio of the rock, based on the digital image correlation method (DIC) and finite element method (FEM), this paper proposed a parameter field inversion method, namely the DF-PF inversion method. Its inversion accuracy is verified using numerical simulation and laboratory uniaxial compression test. Considering the influences of heterogeneity, stress state and dimension difference, the average inversion error of Young’s modulus field and Poisson’s ratio field are below 10%, and the proportion of elements with an error of less than 15% accounts for more than 86% in the whole specimen model. Compared with the conventional measuring method, the error of macro Young’s modulus and macro Poisson’s ratio calculated by the DF-PF inversion method is less than 2.8% and 9.07%, respectively. Based on the statistical analysis of Young’s modulus field and Poisson’s ratio field, the parameter homogeneity and quantitative function relation between the micro parameter and the principal strain can also be obtained in laboratory tests. The DF-PF inversion method provides a new effective method of testing Young’s modulus field and Poisson’s ratio field of the rocks under complex stress states.

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“…Two-dimensional digital image correlation (2D DIC) technique has been utilized in many studies to obtain full-field strains of specimens using flexural loading. For example, Liu et al used 2D DIC to obtain strain maps of nuclear graphite specimens subjected to 4-point bending loads, whereas Planques et al observed 3-point bending of thermal barrier coatings using 2D DIC [12], [13]. Flexural modulus is a material property associated with bending that must be determined experimentally as it differs from elastic modulus under non-ideal conditions.…”

Section: Introductionmentioning

confidence: 99%

Flexural testing of cellulose fiber braided composites using three dimensional digital image correlation

Unlusoy

Melenka

2019

Composite Structures

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Inverse identification of tensile and compressive damage properties of graphite material based on a single four-point bending test

Cited by 17 publications

References 17 publications

In situ measurement of elastic and total strains during ambient and high temperature deformation of a polygranular graphite

In situ measurement of elastic and total strains during ambient and high temperature deformation of a polygranular graphite

Inversion Method of the Young’s Modulus Field and Poisson’s Ratio Field for Rock and Its Test Application

Flexural testing of cellulose fiber braided composites using three dimensional digital image correlation

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