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Interplay between Micro-Anisotropy and Macro-isotropy on Evolution of Non-Equilibrium Morphology

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Journal of Rare Earths 2006年第Z1期24卷 208-212页

作者： Zhao Shanrong Liu Rong Liu Huifang Wang Jiyang China University of Geosciences Wuhan 430074 China China University of Geosciences Wuhan 430074 China China University of Geosciences Wuhan 430074 China State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

Non-equilibrium morphology has received much attention from both scientific and engineering points of view for its intricate pattern selection mechanisms and useful industrial application. Most study of non-equilibrium is about the metal, alloy and other simple system. The complex silicate system is rarely involved. However, silicate is very important in geosciences and ceramic industry. In this paper, two kinds of non-equilibrium crystal morphologies of silicate: dendrite of diopside and spherulite of plagioclase, were introduced. Combining with the other kinds of non-equilibrium morphologies, the characteristics of micro-macro and anisotropy-isotropy of the non-equilibrium morphologies were discussed. Dendrite of diopside is micro- and macro-anisotropic, spherulite of plagioclase is micro-anisotropic, but macro-isotropic, fractal of NH4Cl is also micro-anisotropic, but macro-isotropic, dense-branching morphology (DBM) formed in non-crystalline system is micro-and macro-isotropic. Based on the micro-macro interplay on the pattern formation, it is proposed that the interplay between micro-anisotropy of crystal structure vs macro-isotropy of undercooling in crystal growth system will control the morphological evolution. The nucleation rate related to the anisotropy for the morphological evolution was also discussed. The fact that diopside develops dendrite and plagioclase develop spherulite in our experiment is due to their structural anisotropy difference.

关键词： crystal morphology silicate non-equilibrium anisotropy and isotropy

Force/Moment isotropy of 8/4-4 Parallel Six-Axis Force Sensor Based on Performance Atlases

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第6期35卷 1018-1026页

作者： Song Weishan Li Chenggang Wang Chunming Song Yong Wu Zefeng Rajnathsing Hemant College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics

A six-axis force sensor with parallel 8/4-4 structure is introduced and its measurement principle is analyzed.Based on condition numbers of Jacobian matrix spectral norm of the sensor,the relationship between the force and moment isotropy and some structural parameters is deduced.Orthogonal test methods are used to determine the degree of primary and secondary factors that have significant effect on sensor characteristics.Furthermore,the relationship between each performance index and the structural parameters of the sensor is analyzed by the method of the atlas,which lays a foundation for structural optimization design of the force sensor.

关键词： six-axis force sensor Jacobian matrix condition number isotropy orthogonal test indices atlases

Interaction between transverse isotropy rock slope and supporting structure

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Journal of Central South University 2008年第S1期15卷 415-423页

作者：段靓靓方理刚 College of Civil Engineering Architecture and MechanicsCentral South University of Forestry and Technology School of Architectural and Civil Engineering Central South University

In order to study the interaction between transverse isotropy rock mass and supporting structure,the laboratory tests for rock sampled from the slope at expressway project were carried out,and the parameters of elasticity for transverse isotropic rock were determined by the uniaxial compression tests for rock sample with different strike of stratification plane.Then,based on the relationship of stress-stain for transverse isotropic rock mass,the analytical model was established for the interaction between transverse isotropic rock mass and frame beam with pre-stressed anchor cable.Furthermore,the conception of the best anchorage-angle in pre-stressed anchor cable was proposed.At last,the parameters of the interaction between transverse isotropy rock mass and frame beam with pre-stressed anchor cable were investigated by finite element method,and the best anchorage-angle in pre-stressed anchor cable was obtained.The rules of the influence of the directivity of stratification plane on supporting structure were determined.The results show that the analytical model and numerical method on the design of pre-stressed anchor cable with frame beam supporting for transverse isotropy rock slope are reasonable and reliable in practical engineering design.

关键词： rock mechanics transverse isotropy pre-stressed anchor cable frame beam finite element analysis anchorage angle

Amorphous alloys for electrocatalysis:The significant role of the amorphous alloy structure

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Nano Research 2023年第4期16卷 4277-4288页

作者： Xingyun Li Weizheng Cai Dong-Sheng Li Jun Xu Huabing Tao Bin Liu School of Chemical and Biomedical Engineering Nanyang Technological University62 Nanyang DriveSingapore 637459Singapore Department of Biomaterials College of MaterialsXiamen UniversityXiamen 361005China Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials College of Materials and Chemical EngineeringChina Three Gorges UniversityYichang 443002China Fujian Provincial Key Laboratory for Soft Functional Materials Department of PhysicsResearch Institute for Biomimetics and Soft MatterXiamen UniversityXiamen 361005China State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials(iChEM)College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Division of Chemical and Biological Chemistry School of Physical and Mathematical SciencesNanyang Technological University21 Nanyang LinkSingapore 637371Singapore

Amorphous alloys,also known as metallic glasses,are solid metallic materials having long-range disordered atomic structures.Compared to crystalline alloys,amorphous alloys not only have metallic characters,but also possess several distinct properties associated to the amorphous structure,such as isotropy,composition flexibility,unsaturated surface,etc.As a result,amorphous alloys offer a class of highly promising materials for catalyzing electrochemical reactions.In this minireview,the preparation,characterization and electrocatalytic performances of a variety of metallic amorphous alloy materials are summarized.The influences of the amorphous alloy structure on different electrochemical reactions are discussed.Finally,a summary on the advantages and challenges of amorphous alloys in electrocatalysis is provided,along with some perspectives about the future research directions.

关键词： amorphous alloys electrocatalysis nonperiodic atomic structure isotropy metastability

Bending Resistance and Anisotropy of Basalt Fibers Laminate Composite with Bionic Helical Structure

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Journal of Bionic Engineering 2022年第3期19卷 799-815页

作者： Binjie Zhang Qigang Han Hanlin Qin Junqiu Zhang Shichao Niu Zhiwu Han Luquan Ren Key Laboratory of Bionic Engineering(Ministry of Education China)Jilin UniversityChangchun130022China College of Materials Science and Engineering Jilin UniversityChangchun130022China Weihai Institute for Bionic Jilin UniversityWeihai264200China

The appendages of mantis shrimp often bear bending loads from different directions during the in the process of preying on prey with its grazing limb.Hence,it has excellent bending resistance and isotropy to confront complex and changeable external load.The outstanding performance owes to the helical Bouligand structure with a certain interlayer corner,which is also widely found in other natural materials.Hence,the bio-inspired materials with basalt fiber are fabricated with outstanding bending resistance,isotropy and toughness.The research shows laminates with 18°interlayer corners exhibit relatively excellent bending resistance and isotropy,and the laminate with 11.25°interlayer corner has best toughness.Compared with traditional composites,average bending strength along different loading direction of bio-inspired materials increased by 28%,and anisotropy decreased by 86%.Besides,the maximum toughness of laminates can increase to 1.7 times of the original.Following the introduction of interlayer corners,the bio-inspired composite tends to be isotropic.To explore the reason for the change of the isotropic performance caused by diverse interlayer corners,the Finite Element Analysis based on classical laminate theory and Tsai–Wu and Tsai–Hill failure criterion.Besides,further experiments and observations are conducted to explore possible reasons.In conclusion,following the introduction of interlayer corners,the bio-inspired composites tend to be isotropic.This bio-inspired composites are expected to be applied to various complex modern engineering fields,such as vehicle,rail transit and aerospace.

关键词： Helical Bouligand structure Bio-inspired composites Bending resistance isotropy

Anisotropic alumina ceramics with isotropic optical properties

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Journal of Advanced Ceramics 2023年第1期12卷 72-81页

作者： Akio IKESUE Yan Lin AUNG World Lab.Co. Ltd.Nagoya 456-8587Japan

Excellent mechanical and isotropic optical properties are achieved simultaneously from fully dense polycrystalline advanced alumina ceramics with a hexagonal crystal structure,which are optically anisotropic.A small amount(240 ppm)of ZrO_(2) additive is used to synthesize the transparent alumina ceramics with an average grain size of 0.7µm,and locally detected optical distortion(birefringence)is extremely minimized,less than 20 nm/pass.Total transmittance(86%)of the alumina ceramics(thickness=0.3 mm)in ultraviolet(UV)to infrared(IR)regions is similar to that of commercial c-axis sapphire single crystals produced by Czochralski(CZ)method,while the extinction ratio in the visible wavelength area is over 25 dB.Like glass and the c-axis sapphire single crystals,the alumina ceramics can clearly display texts and images on liquid crystal display(LCD)screens.A grain boundary phase of nano-sized Al_(2)O_(3)-ZrO_(2) composition(amorphous)is formed at the grain boundary of the advanced alumina ceramics,which enhances four-point bending strength and fracture toughness(KIC)simultaneously to 921 MPa and 6.8 MPa·m^(0.5),respectively,and hence the mechanical properties are superior to those of the sapphire single crystals.

关键词： alumina anisotropy isotropy fracture toughness(KIC) optical ceramics grain boundary phase

Inhomogeneous material property assignment and orientation definition of transverse isotropy of femur

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Journal of Biomedical Science and Engineering 2009年第6期2卷 419-424页

作者： Hai-Sheng Yang Tong-Tong Guo Jian-Huang Wu Xin Ma 不详

The finite element method has been increasingly adopted to study the biomechanical behavior of biologic structures. Once the finite element mesh has been generated from CT data set, the assignment of bone tissue’s material properties to each element is a fundamental step in the generation of individualized or subject-specific finite element models. The aim of this work is to simulate the inhomogeneous and anisotropic material properties of femur using the finite element method. A program is developed to read a CT data set as well as the finite element mesh generated from it, and to assign to each element of the mesh the material properties derived from the bone tissue density at the element location. Moreover, for cancellous bone in femoral neck and cortical bone in femoral stem, the principal orientations of transverse isotropy were defined based on the tra-becular structures and the haversian system respectively.

关键词： Finite Element Material Property Inhomogeneous Transverse isotropy Femur

Mechanical properties of copper nanocube under three-axial tensile loadings

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Chinese Physics B 2015年第6期24卷 470-475页

作者：杨在林张国伟罗刚 College of Aerospace and Civil Engineering Harbin Engineering University

The mechanical properties of copper nanocubes by molecular dynamics are investigated in this paper. The [100], [110], [111] nanocubes are created, and their energies, yield stresses, hydrostatic stresses, Mises stresses, and the relation- ships between them and strain are analyzed. Some concepts of the microscopic damage mechanics are introduced, which are the basis of studying the damage mechanical properties by molecular dynamics. The [100] nanocube exhibits homo- geneity and isotropy and achieves a balance easily. The [110] nanocube presents transverse isotropy. The [111] nanocube shows the complexity and anisotropy because the orientation sizes in three directions are different. The broken point occurs on a surface, but the other two do not. The [100] orientation model will be an ideal model for studying the microscopic damage theory.

关键词： molecular dynamics damage three-axial tensile loading isotropy

Experimental characterization of anisotropic tensile mechanical behavior of pure titanium tube

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Journal of Iron and Steel Research(International) 2019年第1期26卷 91-101页

作者： Jin-biao Zhou Peng-yan Sun Chang-yu Zhou Xiao-hua He School of Mechanical and Power Engineering Nanjing Technology UniversityNanjing 211816JiangsuChina

The anisotropic tensile mechanical properties of pure titanium(TA2)tubes were studied by means of theoretical analysis,finite element simulation and tensile tests.Based on the stress analysis of circumferential tensile of TA2 tube,an equation for calculating the tangential force of circumferential tensile specimen was established,and the relationship among tangential force,friction and position of ring specimen was analyzed.The finite element simulation analysis of circumferential tensile process of TA2 ring specimen was carried out,which verified the tangential force equation derived from theoretical analysis.The effect of gauge length and friction on necking and tensile load was analyzed,and the optimal gauge length was selected for the ring hoop tensile test.Finally,the axial and circumferential tensile digital image correlation experiments were carried out to verify the theoretical and finite element simulation results.The friction coefficient between TA2 tube and D-blocks(using Teflon lubricant)was determined by the inverse finite element method and the friction experiment,and the true stress-strain curve of TA2 tube was obtained.The results show that the axial and circumfere ntial mechanical behaviors of TA2 tubes are significantly different and an isotropic.

关键词： Pure titanium(TA2)tube Ring hoop tensile test Digital image correlation An isotropy Strain rate