Micromechanical characterization of shales through nanoindentation and energy dispersive x-ray spectrometry

Veytskin, Yuriy; Tammina, Vamsi K.; Bobko, Christopher P.; Hartley, Patrick G.; Clennell, M.B.; Dewhurst, David N.; Dagastine, Raymond R.

doi:10.1016/j.gete.2016.10.004

Cited by 81 publications

(27 citation statements)

References 40 publications

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“…The experimental observations showed that the direction of stress-induced cracks which are generally perpendicular to the maximum principal stress changes toward the bedding orientations. These tests are crucial to understand the effect of material composition and local heterogeneities on the mechanical response of rocks, which, because of their natural genesis, significantly differ from one to another (Bobko and Ulm 2008;Veytskin et al 2017). Hou et al (2016) compared the behavior of shale, coal and sandstone specimens subjected to high-pressure fluid-driven 1 3 fracturing, and observed how different microscopic composition of these materials leads to important differences in the measured values of mechanical properties, strains and crack patterns.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

et al. 2018

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Reliable prediction of fracture process in shale-gas rocks remains one of the most significant challenges for establishing sustained economic oil and gas production. This paper presents a modeling framework for simulation of crack propagation in heterogeneous shale rocks. The framework is on the basis of a variational approach, consistent with Griffith's theory. The modeling framework is used to reproduce the fracture propagation process in shale rock samples under standard Brazilian disk test conditions. Data collected from the experiments are employed to determine the testing specimens' tensile strength and fracture toughness. To incorporate the effects of shale formation heterogeneity in the simulation of crack paths, fracture properties of the specimens are defined as spatially random fields. A computational strategy on the basis of stochastic finite element theory is developed that allows to incorporate the effects of heterogeneity of shale rocks on the fracture evolution. A parametric study has been carried out to better understand how anisotropy and heterogeneity of the mechanical properties affect both direction of cracks and rock strength.

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Section: Introductionmentioning

confidence: 99%

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

et al. 2018

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“…Field-emission scanning electron microscopy (FE-SEM, AURIGA, Zeiss, Germany) was used to observe the microstructure and morphology of samples. The chemical composition was measured by using an energy dispersive X-ray spectrometer (EDS) [12]. X-ray diffraction (XRD) spectra were used to identify the crystal structure through an XRD diffractometer (Bruker AXS Gmbh, Karlsruhe, Germany) operating at 40 kV and 40 mA (Cu Kα = 1.54184 Å as the radiation source).…”

Section: Methodsmentioning

confidence: 99%

In Vitro Properties for Bioceramics Composed of Silica and Titanium Oxide Composites

et al. 2018

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It is important for oral and maxillofacial surgeons to repair craniofacial defects on oral cancer patients or patients with congenital problems. Thus, it is a challenge to develop biomaterials that promote bone regeneration as potential materials for bone repair. This work is devoted to the fabrication of bioceramics composed of silica and titanium oxide with various concentrations of titanium oxide for developing bone repair materials for dentistry and tissue engineering. The silica-based bioceramics were synthesized using the sol–gel method, and titanium oxide was added from the hydrolysis of tetrabutyl titanate. The surface morphology was observed using scanning electron microscopy. The chemical composition was measured using an energy dispersive X-ray spectrometer, and the crystal structure was identified by using an X-ray diffraction diffractometer. The pH value and ion concentrations released in simulated body fluids after immersion with bioceramic samples were measured using a pH meter and inductively coupled plasma mass spectrometry, respectively. In the cell toxicity test, the human osteosarcoma cells (MG63) were used and quantitatively assessed using an MTT assay. The results showed that the proposed bioceramics can be controlled by tuning the Si/Ti ratio to modify the dissolution rate of samples and enhance the formation of apatite. Compared to Dulbecco’s modified Eagle’s medium (DMEM) groups, the cell number of the BG_Ti75 group can be increased to 120%. Furthermore, BG_Ti75 can promote MG63 cell growth with statistical significance and keep the pH value and the released calcium ion concentrations of the soaking environment stable. The proposed bioceramics show potential for bone-regenerating capability.

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“…Shales are one of the most prominently tested porous geological materials to explore their mechanical properties through nanoindentation tests [ 6 , 7 , 31 , 32 , 33 , 34 ]. A recent work based on nanoindentation by Wang et al [ 35 ], on gas-bearing shale rocks particularly highlighted the development of pop-ins.…”

Section: Indentation Load–displacement Curves: Theory and Formulationsmentioning

confidence: 99%

Application of Nanoindentation in the Characterization of a Porous Material with a Clastic Texture

Kasyap

Senetakis

2021

Materials

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In materials science and engineering, a significant amount of research has been carried out using indentation techniques in order to characterize the mechanical properties and microstructure of a broad range of natural and engineered materials. However, there are many unresearched or partly researched areas, such as, for example, the investigation of the shape of the indentation load–displacement curve, the associated mechanism in porous materials with clastic texture, and the influence of the texture on the constitutive behavior of the materials. In the present study, nanoindentation is employed in the analysis of the mechanical behavior of a benchmark material composed of plaster of Paris, which represents a brand of highly porous-clastic materials with a complex structure; such materials may find many applications in medicine, production industry, and energy sectors. The focus of the study is directed at the examination of the influence of the porous structure on the load–displacement response in loading and unloading phases based on nanoindentation experiments, as well as the variation with repeating the indentation in already indented locations. Events such as pop-in in the loading phase and bowing out and elbowing in the unloading phase of a given nanoindentation test are studied. Modulus, hardness, and the elastic stiffness values were additionally examined. The repeated indentation tests provided validations of various mechanisms in the loading and unloading phases of the indentation tests. The results from this study provide some fundamental insights into the interpretation of the nanoindentation behavior and the viscoelastic nature of porous-clastic materials. Some insights on the influence of indentation spacing to depth ratio were also obtained, providing scope for further studies.

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Micromechanical characterization of shales through nanoindentation and energy dispersive x-ray spectrometry

Cited by 81 publications

References 40 publications

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

In Vitro Properties for Bioceramics Composed of Silica and Titanium Oxide Composites

Application of Nanoindentation in the Characterization of a Porous Material with a Clastic Texture

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