scholarly journals Applications of Micro-Indentation Technology to Estimate Fracture Toughness of Shale

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4208
Author(s):  
Qiang Han ◽  
Zhan Qu ◽  
Ping Wang ◽  
Gang Bi ◽  
Guanzheng Qu
Keyword(s):  
Fracture Toughness ◽  
Indentation Test ◽  
Indentation Load ◽  
Wellbore Stability ◽  
X Ray Diffraction ◽  
Theoretical Support ◽  
Macroscopic Fracture ◽  
Magnetic Resonance Scanning ◽  
Micro Indentation ◽  
Selection Of

The fracture toughness of shale is a basic parameter that can provide effective theoretical support for wellbore stability and hydraulic fracturing of a shale reservoir. Due to the composition and microstructure, there are many problems in evaluating the mechanical properties of shale in a macroscopic test. In this paper, the composition and pore distribution of shale were studied by X-ray diffraction and nuclear magnetic resonance. Scanning electron microscopy was used to characterize the pore structure. The setting of experimental parameters and the selection of the indenter were discussed. Micro-indentation technique was proposed and applied to fracture toughness analysis of shale. The results show that Berkovich indenter is more suitable for shale indentation test than Vickers indenter. Fracture toughness of shale indentation is obviously affected by surface roughness and indentation position. Fracture toughness of shale decreases slightly with the increase of the indentation load. The energy analysis result presents that the effect of cracking on the ratio of total/unloading work is minimal when there is no significant stripping on the shale surface. Compared with the experimental method, energy methods can obtain all the analysis parameters from a single indentation test. The results of comparative analysis with macroscopic experiments display that micro-indentation test can effectively predict the macroscopic fracture toughness of shale.

Fracture Characteristic of Single Crystalline Silicon Using Nano-Indentation and Finite Element Analysis

2006 ◽  
Vol 306-308 ◽  
pp. 601-606
Author(s):  
Seung Baek ◽  
Jae Mean Koo ◽  
Chang Sung Seok
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Phase Transformation ◽  
Crystalline Silicon ◽  
Indentation Test ◽  
Indentation Load ◽  
Single Crystalline Silicon ◽  
Element Analysis ◽  
Single Crystalline ◽  
Nano Indentation

Nano-indentation test is used widely to determine the fracture toughness of brittle materials and to provide information on important material properties such as the Young’s modulus and hardness. In this study, using nano-indentation testing, atomic force microscope (AFM), and finite element method (FEM), we performed the indentation fracture toughness and fracture strength measurement for a (100) single crystalline silicon at different load states. In addition, the loads of the phase transformation events during unloading were estimated by the load-depth curves. The phase transformation load and micro-crack propagation events at pop-out during the unloading process depended on the maximum applied indentation load.

The Behaviour of Cross-Linking Filled PP to Micro-Indentation Test

2016 ◽  
Vol 368 ◽  
pp. 138-141
Author(s):  
Martin Ovsík ◽  
Vojtech Šenkeřík ◽  
David Manas ◽  
Miroslav Maňas ◽  
Michal Stanek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Indentation Test ◽  
Polymer Chains ◽  
Beta Radiation ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
Depth Sensing ◽  
Surface Layers ◽  
Micro Indentation ◽  
Different Doses

Cross-linking is a process in which polymer chains are associated through chemical bonds. Radiation, which penetrated through specimens and reacted with the cross-linking agent, gradually formed cross-linking (3D net), first in the surface layer and then in the total volume, which resulted in considerable changes in specimen behaviour. The aim of the experiments was to study the influence of different doses of Beta radiation to the structure and micro-mechanical properties of polypropylene filled by 30% glass fiber (PP+GF). Hard surface layers of PP+GF can be formed by radiation cross-linking by β – radiation with doses of 33, 66 and 99 kGy. Material properties created by β – radiation are measured by micro-indentation test using the DSI method (Depth Sensing Indentation). Individual radiation doses caused structural and micro-mechanical changes which have a significant effect on the final properties of the PP+GF tested. Micro-mechanical properties increased with increasing value of the dose of irradiation material (increase about 49%). The changes were examined and confirmed by X-ray diffraction.

Micro-Indentation Test and Morphology of Electron Beam Irradiated HDPE

2015 ◽  
Vol 662 ◽  
pp. 189-192
Author(s):  
Martin Ovsik ◽  
Petr Kratky ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Indentation Test ◽  
Polymer Chains ◽  
Cross Linking ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
Irradiation Dosage ◽  
The Cross ◽  
Micro Indentation ◽  
Different Doses

Cross-linking is a process in which polymer chains are associated through chemical bonds. The cross-linking level can be adjusted by the irradiation dosage and often by means of a cross-linking booster. The polymer additional cross-linking influences the surface nanoand micro layers in the way comparable to metals during the thermal and chemical-thermal treatments. The aim of this paper is to study the effect of ionizing radiation with different doses (33, 66 and 99 kGy), on micro-mechanical properties of polyethylene (HDPE) and compare these results with those of non-irradiated samples. Influence of the cross-linking by β – radiation of the tested HDPE on micro-indentation test and morphology was investigated. Micro-mechanical properties increased with increasing value of the dose of irradiation material. The changes were examined and confirmed by X-ray diffraction.

Numerical Analysis of Three-Dimensional Semi-Elliptical Interfacial Cracks Subjected to Indentation Load

2014 ◽  
Vol 627 ◽  
pp. 289-292 ◽  
Author(s):  
N. Kurihara ◽  
Masayuki Arai
Keyword(s):  
Fracture Toughness ◽  
Three Dimensional ◽  
Analytical Formula ◽  
Interfacial Crack ◽  
Indentation Test ◽  
Interfacial Fracture ◽  
Indentation Load ◽  
J Integral ◽  
Interfacial Fracture Toughness ◽  
Interfacial Cracks

The aim of this study is to show elastic J-integral needed to evaluate the interfacial fracture toughness of bi-material in indentation test. Three dimensional J-integrals along the crack front tip in semi-elliptical crack lying on the interface were analyzed using domain integral technique installed in commercialized finite element code MARC. The J-integral was calculated under several kind of aspect ratio of semi-elliptical cracks. In order to have to evaluate the interfacial fracture toughness from interfacial crack length and indentation load obtained in indentation tests, the analytical formula for two dimensional interfacial crack J-integral under plane stress, which had been introduced by J. R. Rice and G. C. Sih, was modified in reflecting upon the three dimensional effect. Finally, the indentation test was conducted for Aluminum alloy/ PMMA combination sample, and the associated fracture toughness was evaluated.Fig.1 Schematic illustration of indentation testFig.2 Schematic illustration of analysis mode

scholarly journals A predictable smoothing evolution model for computer-controlled polishing

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Jing Hou ◽  
Pengli Lei ◽  
Shiwei Liu ◽  
Xianhua Chen ◽  
Jian Wang ◽  
...  
Keyword(s):  
Evolution Model ◽  
Quantitative Prediction ◽  
Theoretical Support ◽  
Model Combining ◽  
Process Guidance ◽  
Dependent Model ◽  
Computer Controlled Optical Surfacing ◽  
Computer Controlled ◽  
Time Dependent Model ◽  
Selection Of

AbstractQuantitative prediction of the smoothing of mid-spatial frequency errors (MSFE) is urgently needed to realize process guidance for computer controlled optical surfacing (CCOS) rather than a qualitative analysis of the processing results. Consequently, a predictable time-dependent model combining process parameters and an error decreasing factor (EDF) were presented in this paper. The basic smoothing theory, solution method and modification of this model were expounded separately and verified by experiments. The experimental results show that the theoretical predicted curve agrees well with the actual smoothing effect. The smoothing evolution model provides certain theoretical support and guidance for the quantitative prediction and parameter selection of the smoothing of MSFE.

scholarly journals The therapeutic mechanism of epilepsy seizures in different target areas: Research on a theoretical model

2021 ◽  
Vol 29 ◽  
pp. 455-461
Author(s):  
Bing Hu ◽  
Zhizhi Wang ◽  
Minbo Xu ◽  
Luyao Zhu ◽  
Dingjiang Wang
Keyword(s):  
Pyramidal Neurons ◽  
Control Mechanism ◽  
Difficult Problem ◽  
Calculation Model ◽  
Thalamic Reticular Nucleus ◽  
Reticular Nucleus ◽  
Theoretical Support ◽  
Therapeutic Mechanism ◽  
Optimal Target ◽  
Selection Of

BACKGROUND: The selection of optimal target areas in the surgical treatment of epilepsy is always a difficult problem in medicine. OBJECTIVE: We employed a theoretical calculation model to explore the control mechanism of seizures by an external voltage stimulus acting in different nerve nuclei. METHODS: Theoretical analysis and numerical simulation were combined. RESULTS: The globus pallidus, excitatory pyramidal neurons, striatal D1 neurons, thalamic reticular nucleus and specific relay nuclei were selected, we analyzed that the electrical stimulation has different effects in these target areas. CONCLUSIONS: The data selected were reasonable in study, the results may give a theoretical support for similar studies in clinical.

Organoclay-reinforced polyethersulfone-modified epoxy-based hybrid nanocomposites

2011 ◽  
Vol 23 (7) ◽  
pp. 526-534 ◽  
Author(s):  
Yang Wang ◽  
Boming Zhang ◽  
Jinrui Ye
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Electron Microscope ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Hybrid Nanocomposites ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Modified Epoxy ◽  
Scanning Electron

Hybrid nanocomposites were successfully prepared by the incorporation of polyethersulfone (PES) and organoclay into epoxy resin. They had higher fracture toughness than the prepared PES/epoxy blend and organoclay/epoxy nanocomposites. The microstructures of the hybrid nanocomposites were studied. They were comprised of homogeneous PES/epoxy semi-interpenetrating network (semi-IPN) matrices and organoclay micro-agglomerates made up of tactoid-like regions composed of ordered exfoliated organoclay with various orientations. The former was confirmed with dynamic mechanical analysis, scanning electron microscopy and transmission electron microscopy, while the latter was successfully observed with X-ray diffraction measurements, optical microscope, scanning electron microscope and transmission electron microscope. The improvement of their fracture toughness was due to the synergistic toughening effect of the PES and the organoclay and related to their microstructures.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of Al2O3-TiC-ZrO2 Ceramic Composites

2012 ◽  
Vol 476-478 ◽  
pp. 1031-1035
Author(s):  
Wei Min Liu ◽  
Xing Ai ◽  
Jun Zhao ◽  
Yong Hui Zhou
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Temperature ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Al2O3-TiC-ZrO2ceramic composites (ATZ) were fabricated by hot-pressed sintering. The phases and microstructure of the composites were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The relative density and mechanical properties (flexural strength, fracture toughness and Vicker’s hardness) of the composites were tested. The results show that the microstructure of the composites was the gray core-white rim. With the increase of sintering temperature, the relative density and mechanical properties of the composites increased first and then decreased. The composite sintered at 1705°C has the highest synthetical properties, and its relative density, flexural strength, fracture toughness and Vickers hardness are 98.3%,970MPa,6.0 MPa•m1/2and 20.5GPa, respectively.

Macroscopic Fracture Behaviour of CrN Hard Coatings Evaluated by X-Ray Diffraction Coupled with Four-Point Bending

2013 ◽  
Vol 768-769 ◽  
pp. 272-279
Author(s):  
Mario Stefenelli ◽  
Angelika Riedl ◽  
Juraj Todt ◽  
Matthias Bartosik ◽  
Rostislav Daniel ◽  
...  
Keyword(s):  
Fracture Stress ◽  
Fracture Behavior ◽  
Fracture Behaviour ◽  
Hard Coatings ◽  
Relevant Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Four Point Bending ◽  
Macroscopic Fracture ◽  
Crn Coatings

Fracture behavior of hard nanocrystalline coatings decisively influences the lifetime and performance of coated tools. In this work, residual stresses in as-deposited and annealed CrN coatings deposited at 350 °C using bias voltages of −40 V and −120 V were evaluated using synchrotron X-ray diffraction coupled with four-point bending. The stress development during the bending experiments was used to analyse fracture properties of the coatings. The results indicate that an annealing at 550 °C does not deteriorate the fracture behavior of the coatings prepared using −40 V bias. In the case of −120 V bias coatings, the residual stress relaxation after the thermal treatment is accompanied by a fracture strain decrease and a fracture stress increase. The as-deposited and annealed CrN coatings deposited using −120 V bias exhibit significantly large fracture strains in comparison with −40 V samples. Finally the results document that the fracture stress may not be the only relevant parameter when comparing different coating systems. Also the strain at fracture can be considered as significant indicator of the coating fracture response. Methodologically, the results indicate that in-situ X-ray diffraction coupled with four point bending can be effectively used to evaluate macroscopic fracture behaviour of hard coatings.

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