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Uncovering the creep deformation mechanism of rock-forming minerals using nanoindentation

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International Journal of Mining Science and Technology 2022年第2期32卷 283-294页

作者： Zhaoyang Ma Chengpeng zhang Ranjith Pathegama Gamage guanglei zhang Deep Earth Energy Laboratory Building 60Monash UniversityMelbourneVictoria 3800Australia State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China Department of Earth Science and Engineering Imperial College LondonLondon SW72BPUK

The creep phenomenon of rocks is quite complex and the creep mechanisms are far from being well *** laboratory creep tests have been carried out to determine the creep deformation of various rocks,these tests are expensive and *** creep tests,as an alternative method,can be performed to investigate the mechanical and viscoelastic properties of granite *** this study,the reduced Young’s modulus,hardness,fracture toughness,creep strain rate,stress exponent,activation volume and maximum creep displacement of common rock-forming minerals of granite were calculated from nanoindentation *** was found that the hardness decreases with the increase of holding time and the initial decrease in hardness was swift,and then it decreased *** stress exponent values obtained were in the range from 4.5 to 22.9,which indicates that dislocation climb is the creep deformation *** addition,fracture toughness of granite’s rock-forming minerals was calculated using energy-based method and homogenization method was adopted to upscale the micro-scale mechanical properties to macro-scale mechanical *** but not least,both three-element Voigt model and Burgers model fit the nanoindentation creep curves *** study is beneficial to the understanding of the long-term mechanical properties of rock samples from a microscale perspective,which is of great significance to the understanding of localized deformation processes of rocks.

关键词： Nanoindentation Granite Time-dependent creep Stress exponent Strain rate sensitivity Fracture toughness

Mechanical response and microscopic damage mechanism of pre-flawed sandstone subjected to monotonic and multilevel cyclic loading:A laboratory-scale investigation

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International Journal of Mining Science and Technology 2023年第12期33卷 1487-1510页

作者： Kesheng Li Shengqi Yang Chuanxiao Liu Yun Chen guanglei zhang Qing Ma State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 221116China College of Water Conservancy and Civil Engineering Shandong Agricultural UniversityTai’an 271018China School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

This study aims to investigate the mechanical response and acoustic emission(AE)characteristic of pre-flawed sandstone under both monotonic and multilevel constant-amplitude cyclic ***,we explored how coplanar flaw angle and load type impact the strength and deformation behavior and microscopic damage *** indicated that being fluctuated before rising with increasing fissure angle under monotonic loading,the peak strength of the specimen first increased slowly and then steeply under cyclic *** effect of multilevel cyclic loading on the mechanical parameters was more *** a single fatigue stage,the specimen underwent greater deformation in early cycles,which subsequently *** variation pattern was also reflected by AE count/energy/*** behaviors were dominated by the fissure angle and load type and medium-scale crack accounted for 74.83%–86.44%of total *** with monotonic loading,crack distribution of specimen under cyclic loading was more ***,a simple model was proposed to describe the damage evolution of sandstone under cyclic ***,SEM images revealed that the microstructures at the fracture were mainly composed of intergranular fracture,and percentage of transgranular fracture jumped under cyclic loading due to the rapid release of elastic energy caused by high loading rate.

关键词： Sandstone Pre-existing coplanar flaws Multilevel constant-amplitude cyclic loading Mechanical behavior Microscopic damage mechanism

Dynamic crushing behavior and energy absorption of hybrid auxetic metamaterial inspired by Islamic motif art

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Applied Mathematics and Mechanics(English Edition) 2023年第3期44卷 345-362页

作者： Ruilan TIAN Huaitong GUAN Xuhao LU Xiaolong zhang Huanan HAO Wenjie FENG guanglei zhang Department of Engineering Mechanics Hebei Key Laboratory of Mechanics of Intelligent Materials and StructuresShijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Materials Science and Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Auxetic honeycomb structures are promising metamaterials with outstanding mechanical properties,and can be potentially used in energy absorption *** this study,a novel modified re-entrant hybrid auxetic metamaterial inspired by Islamic motif art is designed by integrating four-pointed double re-entrant motifs with symmetric semi-hexagonal unit cells to achieve a high energy absorption capacity(EAC).Theoretical analyses and numerical simulations are performed to examine the dynamic crushing behavior of the four-pointed double re-entrant combined structure(FDRCS).The developed finite element models(FEMs)are validated by the experiments under quasi-static *** deformation mode and stress-strain curves are further studied under low,medium,and high crushing *** theoretically predicted plateau stress of the FDRCS under different crushing velocities is consistent with the numerical simulation *** crushing stress and the EAC of the FDRCS are influenced by the geometric parameters and crushing *** FDRCS exhibits a negative Poisson's ratio(NPR),owing to the four-point re-entrant structure(RES).Moreover,the specific energy absorption(SEA)of these structures is higher than that of nonauxetic hexagonal and auxetic re-entrant structures,owing to the generation of more plastic hinges that dissipate more energy during dynamic crushing.

关键词： re-entrant honeycomb auxetic hybrid metamaterial energy-absorption dynamic crushing

Direct Evidence of Coal Swelling and Shrinkage with Injecting CO_(2) and N_(2) Using in-situ Synchrotron X-ray Microtomography

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Engineering 2022年第11期18卷 88-95页

作者： guanglei zhang P.G.Ranjith Herbert E.Huppert Department of Earth Science and Engineering Imperial College LondonLondon SW72BPUK Deep Earth Energy Laboratory Department of Civil EngineeringMonash UniversityMelbourneVIC3800Australia Institute of Theoretical Geophysics King’s CollegeCambridge CB21STUK

Deep coal seams are one of the world’s most widespread deposits for carbon dioxide(C02)disposal and are generally located near large point sources of CO_(2)*** injection of CO_(2)into coal seams has great potential to sequester CO_(2)while simultaneously enhancing coalbed methane(CO_(2)-ECBM)*** tests of CO_(2)-ECBM have been conducted in coal seams worldwide with favorable early ***,one of the main technical barriers in coal seams needs to be resolved:Injecting CO_(2)reduces coal permeability and well ***,using in situ synchrotron X-ray microtomography,we provide the first observational evidence that injecting nitrogen(N_(2))can reverse much of this lost permeability by reopening fractures that have closed due to coal swelling induced by CO_(2)*** findings support the notion that injecting minimally treated flue gas-a mixture of mainly N_(2) and CO_(2)-is an attractive alternative for ECBM recovery instead of pure CO_(2)injection in deep coal ***,flue gas produced by power plants could be directly injected after particulate removal,thus avoiding high CO_(2)-separation ***,the presence of N_(2)makes it possible to maintain a sufficiently high level of coal *** results suggest that flue-gas ECBM for deep coal seams may provide a promising path toward net-zero emissions from coal mines.

关键词： CCS CO_(2)-ECBM Carbon neutrality X-ray imaging Coal permeability

How Do Mind-Body Practices Benefit Employees? A Daily Diary Study of Mind–Body Practices after Work and Employees’ Next-Day Proactive Behavior

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International Journal of Mental Health Promotion 2023年第1期25卷 45-62页

作者： Puwen Shang Jinfan Zhou guanglei zhang School of Management Wuhan University of TechnologyWuhan430070China Department of Human Resource Management School of BusinessNanjing UniversityNanjing210093China

Although it is becoming increasingly popular for organizations to offer programs of mind–body practices to their employees to improve their physical and mental health,the effects that after-work sessions of mind–body prac-tices have on employees’work behavior remain *** the model of proactive motivation and experience sampling,this study explored the relationship between employees’mind–body practices after work and their proactive behavior in the workplace on the following day.A multilevel path analysis of data from 82 employees over seven consecutive workdays showed that employees’mind–body practices after work had a positive effect on their proactive behavior in the workplace on the following *** relationship was mediated by next-day high-activated positive affect and problem-solving conﬁ***,job control positively moderated the rela-tionship between high-activated positive affect and proactive behavior but not that between problem-solving con-ﬁdence and proactive *** discuss the theoretical and practical implications of theseﬁndings,and propose future research directions.

关键词： Mind-body practices proactive motivation proactive behavior non-work experiences

Electronic Band Gap of ZnO under Triaxial Strain

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Journal of Wuhan University of Technology(Materials Science) 2013年第1期28卷 48-51页

作者：秦国强 zhang guanglei YANG Jinhui YU Gang FU Hua JI Fengqiu School of Materials Science and Engineering Shijiazhuang Tiedao University State Key Laboratory of Metastable Materials Science and Technology (Yanshan University)

The effect of triaxial strains on the band gap of wurtzite ZnO has been investigated by the first principles calculations. The results indicate that, after application of triaxial strain, the wurtzite ZnO is still a direct band gap semiconductor with conduction- and valence-band minima remains at the F point. Comparing with the unstrained ZnO, the Eg at F point increases under compressive strain but decreases under tensile strain. This triaxial strain model is in better agreement with the experimental results than the widely-employed in-plane biaxial strain model, thus providing a more accurate explanation on the behaviors of ZnO thin film under threedimensional strain.

关键词： first principles calculations ZnO strain band gap

Adsorption Properties of Calcined Modified Sepiolite on SO4^2- and Cl^-

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Journal of Wuhan University of Technology(Materials Science) 2020年第1期35卷 32-41页

作者：孙凯利王彩辉 zhang guanglei NIU Han FU Shifeng WU Yueze YANG Jinhui State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China Hebei Institute of Technology Co. Ltd.ShiJiaZhuang 050021China

Three different kinds of sepiolite(Type A, Type B and Sepiolite fiber) were processed by calcination and analyzed by thermogravimetric analysis(TG), X-ray diffraction diffractometer(XRD), scanning electron microscopy(SEM), BET(specific surface area from N2 adsorption isotherms), mercury intrusion porosimetry(MIP), and infrared spectroscopic analysis(IR), respectively. The results show that the adsorption performance of sepiolite can be changed by calcination and environment temperatures, especially for calcination. The adsorption capacity of sepiolite fiber is bigger than that of Type A and B, and adsorption capacity of each sepiolite to sulfate is smaller than that of the chloride ions. Especially, the maximum value for adsorption of the sepiolite fibers, calcined at 600 ℃ and water bath at 60 ℃, to chlorine ion and sulfate are 5.95 and 5.71 mg/g, respectively(mg/g : the ions quantity adsorbed by a unit of sepiolite weight). The minimum adsorption of calcined sepiolite fiber to sulfate ions increased from 5.02 to 5.55 mg/g. While microstructure analysis of sepiolite by TG indicated that its structure was, for temperature not exceeding 700 ℃, was not changed significantly. Sepiolite has a porous structure, especially for sepiolite fiber, which can be observed by SEM. BET indicates that sepiolite fiber has a larger pore volume than others and this can be increased by calcination. IR shows that the adsorption of sepiolite to Cl-and SO42- belongs to physical absorption, instead of chemisorption.

关键词： adsorption chloridion sepiolite sulfate ion temperature

Effects of Internal Relaxation under Inplane Strain on the Structural,Electronic and Optical Properties of Perovskite BaZrO3

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Journal of Wuhan University of Technology(Materials Science) 2017年第2期32卷 397-402页

作者：秦国强 PENG Xiaojun zhang guanglei WU Hongya WANG Caihui YU Gang FU Hua Hebei Provincial Key Laboratory of Traffic Engineering Materials Shijiazhuang Tiedao University Shijiazhuang 050043 China School of Materials Science and Engineering Shijiazhuang Tiedao University Shijiazhuang 050043 China

We present the specific ab-initio calculations that detail the variations of perovskite BaZrO3 caused by in-plane strain. Specifically, the internal relaxation, which was not captured in the widely used biaxial strain model, was included in a complementary manner to lattice relaxation. Density functional theory as well as a hybrid functional method based on a plane wave basis set was employed to calculate the lattice structure, elastic constants, electronic properties and optical properties of perovskite BaZrO3. The lattice parameter c exhibited a clear linear dependence on the imposed in-plane strain, but the Poisson＇s ratio caused by internal relaxation was smaller than the elastic deformation, indicating an ＂inelastic＂ or ＂plastic＂ relaxation manner caused by the introduction of internal relaxation. As a result, the related electronic and optical properties of perovskite BaZrO3 were also strongly affected by the in-plane strain, which revealed an effective way to adjust the properties of perovskite BaZrO3 via internal relaxation.

关键词： thin films internal relaxation in-plane strain perovskite electronic band structure computer simulations optical properties

The model of electrified cell clusters in biological tissues basing on the resting potential difference

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Medicine in Novel Technology and Devices 2023年第2期18卷 74-80页

作者： Yufang He Peiguo Xu Huijie Wu Yong Chu guanglei zhang Beijing Advanced Innovation Center for Biomedical Engineering School of Biological Science and Medical EngineeringBeihang UniversityBeijing100191China Yantai Yuhuangding Hospital YantaiShandong Province264000China Institute of Animal Husbandry and Veterinary Medicine Beijing Academy of Agriculture and Forestry SciencesBeijing100097China

The resting potential is the potential difference that exists between the inner and outer sides of the cell membrane when the cell is not *** resting membrane potential is a key regulator of phenomena such as cell proliferation,morphogenesis,migration and *** this paper,we proposed a model of electrified cell clusters that considers the resting potential of cell clusters in the resting *** measuring the potential difference between the inner and outer sides of biological tissues,it is verified that the cell cluster has a negative potential difference when taking the outer potential as the *** the absence of external conductors,the tissue is electrically neutral;while in the presence of external conductors,the positive net charges escape freely under repulsive forces and the biological tissues form a negative electrical equilibrium *** model proposed in this study explored the potential situation above the cellular level in the resting state,providing a new perspective for the research on resting potential.

关键词： Electrified cell clusters Negative electrical equilibrium system Resting potential Biological tissues