Ma ZhaoyangMonash University (Australia) · Department of Civil Engineering, Clayton
https://www.youtube.com/watch?v=Ofjj0KWQsnk King Abdullah University of Science and Technology
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Citations since 2017
21 Research Items
I am currently trying to simulate the fluid flow in the enhanced-geothermal system from a nanoscale perspective by using the molecular dynamics simulation method. The first step is to obtain the mechanical properties of rock minerals. Nanoindentation tests have been carried out to obtain Young's modulus, hardness, time-dependent creep and fracture toughness of rock-forming minerals of granite, namely, quartz, feldspar and mica.
October 2016 - May 2017
Shenzhen, Tsinghua University
- Visiting researcher
- Natural gas hydrate; GROMACS; micromechanical apparatus
Mine dust is one of the main hazards in underground longwall mines worldwide. In order to solve the mine dust problem, a significant number of studies have been carried out regarding longwall mine dust control, both in China and Australia. This paper presents a comparative study of dust control practices in Chinese and Australian longwall mines, wi...
Micro-proppants with stronger portability have more potential to migrate to the massive micro-sized secondary fractures (SFs) or natural fractures activated by supercritical CO2 (Sc-CO2) fracturing in shale gas reservoirs. However, the transportation behaviour of micro-proppants in massive SFs has been scarcely studied to date. In this study, we re...
The poor proppant-carrying capacity of SC-CO2 fracturing (SCF) negates its potential advantages for the exploitation of deep unconventional gas reservoirs over traditional water-based fracturing (WBF). The low proppant concentration in SCF-created fractures leads to accelerated proppant damage behaviours under high in-situ stress, such as proppant...
Supercritical CO2 (ScCO2) fracturing is a preferred alternative to water-based fracturing for stimulation of the shale gas reservoirs, and also promotes CO2 geological sequestration. The injected ScCO2 will interact with shale minerals and then induce changes in rock matrix micromechanics. In this study, a series of nanoindentation tests was conduc...
The creep phenomenon of rocks is quite complex and the creep mechanisms are far from being well understood. Although laboratory creep tests have been carried out to determine the creep deformation of various rocks, these tests are expensive and time-consuming. Nanoindentation creep tests, as an alternative method, can be performed to investigate th...
Micro-mechanics of granite is of vital importance because it will contribute to the understanding of the deformation and failure mechanism of granite from a micro-scale perspective. The deformation and fracture properties of rocks are closely related to the mechanical properties of its basic constituents. Nanoindentation tests can be carried out to...
Understanding the mechanical properties of α-quartz is of vital importance to rock engineering because α-quartz is the main component of igneous, metamorphic and sedimentary rocks. Molecular dynamics simulations (MDs) of nanoindentation tests on α-quartz were performed to investigate the effects of indenter tip radius and penetration depth on the m...
Structural integrity and mechanical stability of coal are important regarding the long-term safety of CO2 sequestration in coal. To date, little understanding exists on long-term effects of CO2 injection at presence of water on structural and mechanical properties of coal. In this study, bituminous coal samples were saturated with CO2 at pressures...
CO2-based fracturing (CBF) has been regarded as the most promising alternative to water-based fracturing (WBF) in water-sensitive unconventional gas reservoirs, and the fracture initiation and propagation at different in-site stresses created by CBF is crucial to the flow conductivity of fracture network. The main aim of this study is to compare th...
Nanoindentation has become an increasingly popular method to determine the mechanical properties of both homogeneous and heterogeneous materials. Rocks are inherently heterogeneous and understanding their mechanical properties is of vital importance for relevant engineering applications. Due to its high precision and resolution in both force and di...
In this article, a series of molecular dynamics (MD) simulations were performed to investigate the impacts of indentation size, grain size and temperature on the mechanical properties of polycrystalline α-quartz under quasi-static nanoindentation with conical indenter. Results from MD simulations show that the hardness and Young’s modulus are more...
CO2 fracturing can perform better in enhancing the unconventional gas production than water-based fracturing by avoiding serious reservoir permeability damage. The evolution of the fracture permeability of created and natural fractures during exposure to different fracturing fluids is critical to the effectiveness of CO2 fracturing. Therefore, a co...
This work presents results on grain scale cracking behaviors, inhomogeneous deformation and fracture process zone of Harcourt granite under tensile conditions. Brazilian test was performed with cracking initiation and propagation being monitored by a high speed camera (2×10^5 frames/s). Digital image correlation (DIC) was utilized to obtain full-fi...
This review summarizes current progress in molecular dynamic (MD) simulation in the context of geological high-level radioactive waste disposal (HLRW). Geological HLRW disposal is a long-term thermal-hydraulic-mechanical-chemical (THMC) coupling process; hence, it is difficult to model actual geological HLRW disposal conditions experimentally. MD s...
In underground coal mining systems, the subsidence of unstable overlying strata (UOS) has a key effect on the deformation of narrow coal pillars that are contiguous to the caved zone. This paper investigated the failure mechanism of coal pillars by combining the in situ testing and numerical modeling methods. Several striking findings can be drawn....
Mechanical behaviors of geomaterials under plane-strain biaxial stress state (PSBSS, a special case 9 of biaxial stress state) are often considered in geotechnical structures such as highwall and longwall coal 10 pillars. In this study, a new statistical damage constitutive model based on Weibull distribution was 11 established to explain the mecha...
A mathematical model of heat conduction in surrounding rocks of the high geothermal roadway with thermal insulation layer was established in this paper, and its finite difference scheme was also proposed. On this basis, thermal insulation mechanism of thermal insulation layer was investigated. Results show that distinct regional temperature distrib...
In order to understand the deformation mechanism of the narrow coal pillar in gob-side entry employing TCC under unstable overlying strata, borehole inspection camera has been utilized to observe the boreholes in the narrow coal pillar. Evaluation method of broken level based on the basic measuring scale has been proposed to undertake the statistic...
I am currently studying the nanoindentation of solids; currently I can obtain the Young's modulus and hardness of the solid material. However, I wanna observer the deformation process (especially the plastic deformation processing) during the simulation process. How can I achieve this aim?
I have alpha-quartz powders and I did 3 hours XRD scan for these powders both at 30 degrees Celsius and 450 degrees Celsius (there exists no phase transformation at this temperature). After refining by TOPAS-5, I wonder why my Rwp is 14% for 30 degrees and 19% for 450 degrees. Would you please check to see if the steps mentioned below are correct and Is the attached Rietveld refinement for silica done by TOPAS publishable?
I want to use TOPAS to find out the effects of temperatures on unit cell parameters (trying to calculate the thermal expansion coefficient). I calculated the thermal expansion coefficient of alpha-quartz powders according to the change of the variation in unit cell parameters, as shown in the following table and this result is in accordance with other researcher's value.
First for 30 degrees:
1- I loaded the scan file (30 degrees). 2- load the emission file.
3- set the background order to 4
4- loaded instrument details
5- chose the correction (zero error, sample displacement, LP factor)
6- start X from 22.5 because there exists a large disagreement between the actual scan pattern and fitted scan pattern before 22.5 degree
6- load the quartz.str file (PDF Card - 00-046-1045)
7- I changed all the occ and beg from fix to refine.
8- Run and check the Rwp value
9-Save structure in str format for 450 degrees (named as fitted-30degree.str)
Then for 450 degrees:
1- I loaded the scan file (450 degrees). 2- load the emission file. 3- set the background order to 4 4- loaded instrument details 5- chose the correction (zero error, sample displacement, LP factor) 6- start X from 22.5 6- load the fitted-30degree.str file 7- I changed all the occ and beg from fix to refine. 8- Run and check the Rwp value
I want to get the thermal expansion coefficient of each mineral in a rock using high-tempearture X-ray diffraction (XRD); how can we achieve that using TOPAS software, since there will be peak overlapping during the scan analysis.
What does “lennard-jones fluids” mean? It is a particular fluid type (e.g., water) or a collection of conceptual model for the fluids that satisfies the L-J potential?
I am a novice to LAMMPS and currently, I am reading a thesis named "2008 A molecular dynamics study of void initiation and growth in monocrystalline and nanocrystalline copper". In its appendix, the authors gave out the input script for the simulation, as shown follows:
units metal boundary p p p atom_style atomic lattice fcc 3.6150 origin 0 0 0 orient x 1 0 0 orient y 0 1 0 orient z 0 0 1 region box block -14 14 -14 14 -14 14 region void sphere 0 0 0 10 units box create_box 1 box create_atoms 1 region box group bulk region box group void region void delete_atoms group void pair_style eam/alloy pair_coeff * * cuMishinAlloy Cu neighbor 2.0 bin neigh_modify every 1 delay 5 check yes compute new3d all temp velocity all create 300 14285736 temp new3d thermo 1 thermo_style custom step temp pe ke etotal press vol lx ly lz pxx pyy pzz pxy pxz pyz thermo_modify temp new3d norm yes timestep 0.001 fix 1 all nve dump 1 all custom 5 dump.relax1.* x y z centro vx vy vz sxx syy szz sxy sxz syz tag epair ke restart 10 restart.relax1.* run 10
However, when I tried to run the script, it reminds me
"ERROR on proc 0: Cannot open EAM potential file cuMishinAlloy (../pair_eam_alloy.cpp:131)
Last command: pair_coeff * * cuMishinAlloy Cu"'
Hence, my question is where can I found the potential cuMishinAlloy? Thanks in advance.
In rock engineering, what's the definition of void and what's the relationship between void and fracture? For example, if I adopt molecular dynamics simulation to simulate the void in rocks (mineral), does this have any implication? Does the void evolution represents the variation of permeability value? Also, as shown in the thesis <a molecular dynamics study of void initiaton and growth in monocrystalline and nanocrystalline copper>, it refers to "fracture of ductile metals occurs by nucleation, growth and coalescence of void", what about rocks? Does the "fracture of "rock (mineral)" occurs by nucleation, growth and coalescence of void"?
How to generate animation movies using OVITO (scientific data visualization and analysis software for atomistic simulation models)? I already performed the molecular dynamics simulation of uni-axial tension of aluminium and I can get the figure or each frame of the simulation, as shown in the attached figure, however, how can I get the animation movies (say .avi) using OVITO?
In order to gain the thermodynamics, elasticity, phase transitions properties, the molecular dynamics simulation of rock minerals (say crystalline mineral) can be performed and in this process, what's the relationship between molecular dynamics and lattice dynamics?
Is granite granular material? If not, what about other types of rock? say sandstone or diorite?
As a new beginner, how to learn the software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) faster?
In clay minerals, what does 001, 100 means, do the external basal surface and interlayer basal surface have the same code (number, say 001)?
How can I draw the basic crystal of SiO4 and AlO6 using VESTA, can anybody give a hint?
Nanoindentation tests and simulations will be carried out to investigate the mechanical properties of rock minerals. Inverse analysis methods will be adopted to obtain the constitutive model of these minerals of polycrystalline rocks. In addition, multi-scale analysis and asymptotic expansion homogenization (AEH) will be carried out to obtain the macro-scale properties of polycrystalline rocks using the nanoindentation results as well as the results from XRD qualification, EBSD and thin-section tests.