检索结果-南通市图书馆

Edge effect and interface confinement modulated strain distribution and interface adhesion energy in graphene/Si system

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2021年第1期73卷 122-127页

作者： Ying-Di Huang Jia-Ting Xie Su-Mei Hu Yan He Guangdong University of Petrochemical Technology Maoming 525000China

In order to clarify the edge and interface effect on the adhesion energy between graphene(Gr)and its substrate,a theoretical model is proposed to study the interaction and strain distribution of Gr/Si system in terms of continuum medium mechanics and nanothermodynamics.We find that the interface separation and adhesion energy are determined by the thickness of Gr and substrate.The disturbed interaction and redistributed strain in the Gr/Si system induced by the effect of surface and interface can make the interface adhesion energy decrease with increasing thickness of Gr and diminishing thickness of Si.Moreover,our results show that the smaller area of Gr is more likely to adhere to the substrate since the edge effect improves the active energy and strain energy.Our predictions can be expected to be a guide for designing high performance of Grbased electronic devices.

关键词： graphene edge effect and interface confinement strain distribution adhesion energy

Designing of ECAP parameters based on strain distribution uniformity

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2012年第5期22卷 452-460页

作者： F.Djavanroodi B.Omranpour M.Ebrahimi M.Sedighi Department of Mechanical Engineering Iran University of Science and TechnologyTehranIran

Equal Channel Angular Pressing(ECAP) is currently one of the most popular methods for fabricating Ultra-Fine Grained(UFG) materials.In this work,ECAP process has been performed on commercial pure aluminum up to 8 passes by route A.After verification of FEM work,the influences of four die channel angles,three outer corner angles and pass number up to 8 have been analyzed to investigate strain distribution behavior of ECAPed material.Two methods for quantifying the strain homogeneity namely inhomogeneity index(Ci) and standard deviation(S.D.) are compared.It is shown that Ci is not a good candidate for examining the strain distribution uniformity.Moreover,it is suggested that designing of ECAP die geometry to achieve optimum strain distribution homogeneity is more suitable than the optimum effective strain magnitude.The best strain distribution uniformity in the transverse plane is obtained with Ф=60° and Ψ=15° and for the bulk of the sample,Ф=120° and Ψ=15° or 60°,gives the highest strain dispersal uniformity.

关键词： ECAP FEM Die design strain distribution

Stability Analysis of Landfills Contained by Retaining Walls Using Continuous Stress Method

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2023年第1期134卷 357-381页

作者： Yufang Zhang Yingfa Lu Yao Zhong Jian Li Dongze Liu China Academy of Railway Sciences Corporation Limited Beijing100081China School of Civil Architecture and EnvironmentHubei University of TechnologyWuhan430068China

An analytical method for determining the stresses and deformations of landfills contained by retaining walls is proposed in this paper.In the proposedmethod,the sliding resisting normal and tangential stresses of the retaining wall and the stress field of the sliding body are obtained considering the differential stress equilibrium equations,boundary conditions,and macroscopic forces and moments applied to the system,assuming continuous stresses at the interface between the sliding body and the retaining wall.The solutions to determine stresses and deformations of landfills contained by retaining walls are obtained using the Duncan-Chang and Hooke constitutive models.A case study of a landfill in the Hubei Province in China is used to validate the proposed method.The theoretical stress results for a slope with a retaining wall are compared with FEMresults,and the proposed theoreticalmethod is found appropriate for calculating the stress field of a slope with a retaining wall.

关键词： Stress distribution strain distribution landfill retaining wall numerical analysis

Evolution mechanism of optical fiber strain induced by multi-fracture growth during fracturing in horizontal wells

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Exploration and Development 2022年第1期49卷 211-222页

作者： CHEN Ming GUO Tiankui XU Yun QU Zhanqing ZHANG Shicheng ZHOU Tong WANG Yunpeng College of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China PetroChina Research Institute of Petroleum Exploration&Development Beijing 100083China College of Petroleum Engineering China University of PetroleumBeijing 102249China Research Institute of Petroleum Exploration&Development SinopecBeijing 100083China

A forward model for optical fiber strain was established based on a planar 3D multi-fracture model. Then the forward method calculating distributed fiber strain induced by multi-fracture growth was proposed. Based on this method, fiber strain evolution during fracturing of the horizontal well was numerically simulated. Fiber strain evolution induced by fracture growth can be divided into three stages: strain increasing, shrinkage convergence, and straight-line convergence, whereas the evolution of fiber strain rate has four stages: strain rate increasing, shrinkage convergence, straight-line convergence, and strain rate reversal after pumping stops. Fiber strain does not flip after pumping stop, while the strain rate flips after pumping stop so that strain rate can reflect injection dynamics. The time when the fracture extends to the fiber and inter-well pressure channeling can be identified by the straight-line convergence band of distributed fiber strain or strain rate, and the non-uniform growth of multiple fractures can be evaluated by using the instants of fractures reaching the fiber monitoring well.When the horizontal section of the fiber monitoring well is within the height range of a hydraulic fracture, the instant of the fracture reaching the fiber can be identified;otherwise, the converging band is not apparent. In multi-stage fracturing, under the influence of stress shadow from previous fracturing stages, the tensile region of fiber strain may not appear, but the fiber strain rate can effectively show the fracture growth behavior in each stage. The evolution law of fiber strain rate in single-stage fracturing can be applied to multi-stage fracturing.

关键词： horizontal well multi-stage fracturing optical fiber strain strain distribution forward model identification of multi-fracture growth

Sampling Moiré method for full-field deformation measurement: A brief review

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2022年第1期12卷 42-48页

作者： Qinghua Wang Shien Ri Research Institute for Measurement and Analytical Instrumentation National Metrology Institute of Japan(NMIJ)National Institute of Advanced Industrial Science and Technology(AIST)1-1-1 UmezonoTsukuba 305-8568Japan

The sampling Moiré(SM) method is one of the vision-based non-contact deformation measurement methods, which is a powerful tool for structural health monitoring and elucidation of damage mechanisms of materials. In this review, the basic principle of the SM method for measuring the twodimensional displacement and strain distributions is introduced. When the grid is not a standard orthogonal grating and cracks exist on the specimen surface, the measurement methods are also stated. Two of the most typical application examples are described in detail. One is the dynamic deflection measurement of a large-scale concrete bridge, and the other is the residual thermal strain measurement of small-scale flip chip packages. Several further development points of this method are pointed out. The SM method is expected to be used for deformation measurement of various structures and materials for residual stress evaluation, crack location prediction, and crack growth evaluation on broad scales.

关键词： Displacement measurement strain distribution Bridge Flip chip package

strain distributions and electronic structure of three-dimensional InAs/GaAs quantum rings

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2009年第11期18卷 4667-4675页

作者：刘玉敏俞重远贾博雍徐子欢姚文杰陈智辉芦鹏飞韩利红 Institute of Optical Communication and Optoelectronics Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications) Ministry of Education

This paper presents a finite element calculation for the electronic structure and strain distribution of self-organized InAs/GaAs quantum rings. The strain distribution calculations are based on the continuum elastic theory. An ideal three-dimensional circular quantum ring model is adopted in this work. The electron and heavy-hole energy levels of the InAs/GaAs quantum rings are calculated by solving the three-dimensional effective mass SchrSdinger equation including the deformation potential and piezoelectric potential up to the second order induced by the strain. The calculated results show the importance of strain and piezoelectric effects, and these effects should be taken into consideration in analysis of the optoelectronic characteristics of strain quantum rings.

关键词： quantum ring strain distribution electronic structure

Understanding the role of interface in advanced semiconductor nanostructure and its interplay with wave function overlap

在线全文

学校读者我要写书评

暂无评论

Nano Research 2020年第6期13卷 1536-1543页

作者： Chenyuan Cai Yunhao Zhao Faran Chang Xuebing Zhao Liting Yang Chongyun Liang Guowei Wang Zhichuan Niu Yi Shi Xianhu Liu Yuesheng Li Renchao Che Laboratory of Advanced Materials Department of Materials ScienceCollaborative Innovation Center of Chemistry for Energy MaterialsFudan UniversityShanghai200438China State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing100083China National Laboratory of Solid-State Microstructures School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210093China Key Laboratory of Materials Processing and Mold(Zhengzhou University) Ministry of EducationZhengzhou UniversityZhengzhou450002China

As the proportion of interfaces increases rapidly in nanomaterials,properties and quality of interfaces hugely impact the performance of advanced semiconductors.Here,the effect of interfaces is explored by comparatively studying two InAs/AlSb superlattices with and without the thin InAsSb layers inserted inside each InAs layers.Through strain mapping,it indicates that the addition of interfaces leads to an increase of local strain both near interfaces and inside layers.Meantime,owing to the creation of hole potential wells within the original electron wells,the charge distribution undergoes an extra electron-hole alternating arrangement in the structure with inserted layers than the uninserted counterpart.Such a feature is verified to enhance electron-hole wave function overlap by theoretical simulations,which is a must for better optical performance.Furthermore,with an elaborate design of the inserted layers,the wave function overlap could be boosted without sacrificing other key device performances.

关键词： interface engineering energy band alignment charge distribution strain distribution semiconductor multilayer nanostructures

Damage prediction of 7025 aluminum alloy during equal-channel angular pressing

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2014年第10期21卷 990-998页

作者： M.Ebrahimi Sh.Attarilar C.Gode F.Djavanroodi Department of Mechanical Engineering Iran University of Science and Technology Department of Materials Engineering Sahand University of Technology School of Denizli Vocational Technology Program of Machine Pamukkale University Department of Mechanical Engineering Imperial College

Equal-channel angular pressing （ECAP） is a prominent technique that imposes severe plastic deformation into materials to en- hance their mechanical properties. In this research, experimental and numerical approaches were utilized to investigate the mechanical prop- erties, strain behavior, and damage prediction of ECAPed 7025 aluminum alloy in various conditions, such as die channel angle, outer comer angle, and friction coefficient. Experimental results indicate that, after the first pass, the yield strength, ultimate tensile strength, and hardness magnitude are improved by approximately 95%, 28%, and 48.5%, respectively, compared with the annealed state, mainly due to grain re- finement during the deformation. Finite element analysis shows that the influence of die channel angle is more important than that of outer comer angle or friction coefficient on both the strain behavior and the damage prediction. Also, surface cracks are the main cause of damage during the ECAP process for every die channel angle except for 90°; however, the cracks initiated from the neighborhood of the central re- gions are the possible cause of damage in the ECAPed sample with the die channel angle of 90°.

关键词： aluminum alloys equal-channel angular pressing materials damage strain distribution mechanical properties

Deformation mechanism of bimodal microstructure in Ti-6Al-4V alloy:The effects of intercritical annealing temperature and constituent hardness

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第12期71卷 138-151页

作者： Yan Chong Tilak Bhattacharjee Yanzhong Tian Akinobu Shibata Nobuhiro Tsuji Department of Materials Science and Engineering Kyoto UniversityKyotoJapan Department of Materials Science and Engineering University of CaliforniaBerkeleyCAUSA Elements Strategy Initiative for Structural Materials(ESISM) Kyoto UniversityKyotoJapan Key Laboratory for Anisotropy and Texture of Materials School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Research Center for Metallic Wires Northeastern UniversityShenyang 110819China

The so-called bimodal microstructure of Ti-6 Al-4 V alloy,composed of primaryαgrains(α_(p))and transformed β areas(β_(trans)),can be regarded as a"dual-phase"structure to some extent,the mechanical properties of which are closely related to the sizes,volume fractions,distributions as well as nanohardness of the two constituents.In this study,the volume fractions of primaryαgrains(vol.%(α_(p)))were systematically modified in three series of bimodal microstructures with fixed primaryαgrain sizes(0.8μm,2.4μm and 5.0μm),by changing the intercritical annealing temperature(T_(int)).By evaluating the tensile properties at room temperature,it was found that with increasing T_(int)(decreasing vol.%(α_(p))),the yield strength of bimodal microstructures monotonically increased,while the uniform elongation firstly increased with T_(int)until 910°C and then drastically decreased afterwards,thereby dividing the T_(int)into two regions,namely region I(830-910°C)and region II(910-970℃).The detailed deformation behaviors within the two regions were studied and compared,from the perspectives of strain distribution analysis,slip system analysis as well as dislocation analysis.For bimodal microstructures in region I,due to the much lower nano-hardness ofβ_(trans)thanα_(p),there was a clear strain partitioning between the two constituents as well as a strain gradient from theα_(p)/β_(trans)interface to the grain interior ofα_(p).This activated a large number of geometrically necessary dislocations(GNDs)near the interface,mostly with components,which contributed greatly to the extraordinary work-hardening abilities of bimodal microstructures in region I.With increasing T_(int),theα_(p)/β_(trans)interface length density gradually increased and so was the density of GNDs with components,which explained the continuous increase of uniform elongation with T_(int)in this region.For bimodal microstructures in region II,where the nano-hardness ofβ_(trans)andα_(p)were comparable,neither a clear strain-partitioning tendency nor a strain gradien

关键词： Ti-6Al-4V Bimodal microstructure Intercritical annealing temperature strain distribution dislocation