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Acta Mechanica Sinica 2013年第1期29卷 62-72页

作者： Jian-Lin Liu re xia School of Pipeline and Civil Engineering China University of Petroleum School of Power and Mechanical Engineering Wuhan University

In this study, we developed a general method to analytically tackle a kind of movable boundary problem from the viewpoint of energy variation. Having grouped the adhesion of a micro-beam, droplet and carbon nanotube （CNT） ring on a substrate into one framework, we used the developed line of reasoning to investigate the adhesion behaviors of these systems. Based upon the derived governing equations and transversality conditions, explicit solutions involving the critical parameters and morphologies for the three systems are successfully obtained, and then the parameter analogies and common characteristics of them are thor- oughly investigated. The presented method has been verified via the concept of energy release rate in fracture mechanics. Our analyses provide a new approach for exploring the mechanism of different systems with similarities as well as for understanding the unity of nature. The analysis results may be beneficial for the design of nano-structured materi- als, and hold potential for enhancing their mechanical, chemical, optical and electronic properties.

关键词： Variational theory - Transversality condition Beam adhesion Droplet adhesion Carbon nanotube ring adhesion

A new look on wetting models:continuum analysis

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Science China(Physics,Mechanics & Astronomy) 2012年第11期55卷 2158-2166页

作者： LIU JianLin xia re ZHOU xiaoHua School of Pipeline and Civil Engineering China University of PetroleumQingdao 266555China School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China Department of Mathematics and Physics Fourth Military Medical UniversityXi’an 710032China

In this study,we considered the wetting phenomenon on a general substrate from a new viewpoint of continuum *** analyses first show how the Wenzel and the Cassie models deviate the practical results in some special substrates,and then elucidate the mechanism of the triple contact line(TCL) *** upon variational theory of the total free functional dealing with the movable boundary condition,we show that the macroscopic contact angle(MCA) expression is the corresponding transversality *** manifests that the MCA depends only on the chemical and geometric property at the TCL,and is not affected by the gravity of the droplet and the contact area beneath the *** continuum model also shows the exploration of the pinning effect on a sharp wedge or the interface between two different *** investigation will help designing super-hydrophobic materials for novel micro-fluidic devices.

关键词： continuum field energy functional transversality condition mechanism-based model triple line moving

Bionic surface design of cemented carbide drill bit

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Science China(Technological Sciences) 2016年第1期59卷 175-182页

作者： YANG xiaoFeng xia re ZHOU HongWei GUO Lu ZHANG LiJun School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China Suzhou Institute of Wuhan University Suzhou 215123China School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China State Key Laboratory of Shield Machine and Boring Technology Zhengzhou 450001China

The development of a high-performance cemented carbide drill bit is of great significance to the reduction of rock drilling-cost. The non-smooth features of a biological surface provide an insight into how they can obtain low friction and good wear resistance with evolving surface morphology. By analyzing the mechanism of the surface of a dung beetle for reducing soil wear and adherence, we design a cemented carbide drill bit with a bionic surface, which is expected to have superior anti-wearing and anti-sticking properties for drilling the soft coal seam. Inspired from the characteristics of the head and pronotum surface of the dung beetle, optimized non-smooth surface of the drill bit was constructed. The working performance of this innovative drill was experimentally tested. With comparative experiments under the identical drilling conditions, the wear rates, drilling times of conventional drills and bionic drills were measured. Compared with the conventional counterpart, the drill designed exhibits better performance in reducing wear and sticking drilling-breaks, therefore achieving higher levels of efficiency. The diameter of the dome and pit on the bit surface is in the range of 0.8–1.2 mm, and the bionic drill bits could get better performance with preferable drilling speeds and wear rates.

关键词： cemented carbide drill bit surface bionic design dung beetle friction

Mechanical properties of nanocrystalline nanoporous gold complicated by variation of grain and ligament: A molecular dynamics simulation

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Science China(Technological Sciences) 2018年第9期61卷 1353-1363页

作者： LI JieJie xiaN YueHui ZHOU HongJian WU RunNi HU GuoMing xia re Key Laboratory of Hydraulic Machinery Transients Ministry of Education Wuhan University Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan University

A series of large-scale molecular dynamics(MD) simulations has been performed to study the effects of grain size and ligament diameter on the mechanical properties of nanocrystalline nanoporous gold. Such simulations indicate that the principal deformation mechanism is a combination of grain boundary sliding, grain rotation and dislocation movement. The results of uniaxial tensile tests reveal the presence of a reverse Hall-Petch relation between strength and nominal grain size, rather than the conventional Hall-Petch relationship in the present range of nominal grain size(7.9–52.7 nm). An increase of flow stress may possibly attribute to the lower total proportion of grain boundary sliding and grain rotation in the deformation of samples with larger grain size. The Young's modulus shows a linear relation with the reciprocal of nominal grain size, which depends largely on the volume fraction of grain boundaries and thus decreasing grain size leads to relatively lower Young's modulus. MD simulations on samples with ligament diameter ranging from 4.07 to 8.10 nm are also carried out and results show that the increasing ligament diameter resulted in decreased flow stress and increased Young's modulus.

关键词： nanocrystalline nanoporous gold grain-size effect ligament-size effect mechanical properties molecular dynamics

Stiction of a Nano-Beam with Surface Effect

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Chinese Physics Letters 2011年第11期28卷 186-189页

作者： LIU Jian-Lin xia re ZHOU Yue-Ting Department of Engineering Mechanics China University of PetroleumQingdao 266555 Key Laboratory of Transients in Hydraulic Machinery Ministry of EducationWuhan 430072 School of Mechanical Engineering Yonsei UniversitySeoul 120-749Republic of Korea

Nanowire stiction is a crucial bottleneck for the development of M/NEMS *** present a model of a nano-beam stuck to the substrate in consideration of both surface elasticity and residual surface *** critical detachment length can be derived from the transversality condition using the variational *** effects of the surface parameters on the adhesion of the nano-beam are discussed in *** analyses provide some suggestions for engineers in the design and fabrication of more accurate M/NEMS instruments.

关键词： elasticity beam surface

Fracture toughness and destructive mechanism of ductile nanoporous metallic glass and its crystal-impregnated nanocomposite

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Science China(Technological Sciences) 2023年第11期66卷 3328-3342页

作者： ZHANG YuHang XU JianFei HU YiQun SU Lei DING SuHang WU WenWang xia re Key Laboratory of Hydraulic Machinery Transients(Wuhan University) Ministry of EducationWuhan 430072China Department of Engineering Mechanics School of Naval ArchitectureOcean&Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Nanoporous metallic glasses(NPMGs)and crystalline/amorphous nanocomposites exhibit superior ductility over bulk macroscopic metallic glasses(MGs).Their fracture behaviors remain a mystery due to experimental technical *** this work,the fracture behaviors of pre-cracked NPMGs and crystal-impregnated nanoporous metallic glasses(CINPMGs)are investigated through large-scale molecular dynamics simulations,and the MG and crystal phases are amorphous Cu_(50)Zr_(50)and crystalline B2CuZr,*** toughness is determined by simultaneously considering the surface energy and plastic dissipated *** results confirm the excellent plasticity of both the pre-cracked NPMGs and *** progressive necking and ductile rupture of ligaments are responsible for generating NPMGs with prominent ductility and fracture ***,secondary cracking is also triggered,which can consume energy without extending the major crack,thus further improving fracture *** is also found that the fracture toughness of NPMGs can be improved by increasing the solid fraction of MG,and linear relation between fracture toughness and solid fraction can be *** impregnation effectively inhibits global failure as the crystal phase shields the individual amorphous *** plastic flow characterized by shear bands is observed in CINPMGs,and this homogeneous global deformation is facilitated by the crystalline/amorphous ***,the fracture toughness of CINPMGs is higher than that of the constituent single phases,regardless of the volume fraction of each *** material charts manifest that these two types of materials demonstrate promising potential in the material selection library for advanced structural design.

关键词： nanoporous metals crack fracture toughness nanocomposites metallic glasses

Mechanics and Wave Propagation Characterization of Chiral S-Shaped Auxetic Metastructure

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Acta Mechanica Solida Sinica 2022年第4期35卷 571-586页

作者： Qingsong Zhang Wenjie Hong Jianfei Xu Yuhang Zhang Suhang Ding Wenwang Wu re xia Key Laboratory of Hydraulic Machinery Transients(Wuhan University) Ministry of EducationWuhan430072China School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing100081China Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan UniversityWuhan430072China

Auxetic metastructures have attracted tremendous attention because of their robust multifunctional properties and promising potential industrial *** paper studies the in-plane mechanical behaviors of a chiral S-shaped metastructure subjected to tensile loading in both X-direction and Y-direction and wave propagation properties using the finite element(FE)*** relationships between structural parameters and elastic behaviors are also *** results indicate that the orientation of chiral S-shaped metastructure under tensile loading in the X-direction exhibits higher auxeticity and ***,the band structures and the edge modes of each band gap of the chiral S-shaped metastructure are explored,and the relations between band gap properties and structural parameters are also systematically ***,we explore the wave mitigation of the chiral S-shaped metastructures by regulating the structural ***,the transmission properties of the finite chiral S-shaped periodic metastructures are studied to confirm the results of band gap *** study promotes the engineering application of vibration isolation of chiral structures based on the band gap theory.

关键词： Auxetic metastructures Mechanical properties Band gaps Wave mitigation

Effect of radial heat conduction on effective thermal conductivity of carbon nanotube bundles

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Science China(Technological Sciences) 2018年第12期61卷 1959-1966页

作者： WANG JianLi SONG YaMei ZHANG YuFeng HU YuHan YIN Hang GU YunFeng xia re CHEN YunFei Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments Southeast University College of Electronic and Mechanical Engineering Nanjing Forestry University Key Laboratory of Hydraulic Machinery Transients (Wuhan University) Ministry of Education

The effect of the radial heat conduction on the effective thermal conductivity of carbon nanotube(CNT) bundles is studied by the nonequilibrium molecular dynamics(NEMD) method. The hexagonal CNT bundle consists of seven(10, 10) single-walled carbon nanotubes(SWCNTs). The radial heat conduction is induced by creating the vacancy defects in some segments of the constituent CNTs. Combined with the temperature differences and the inter-tube thermal resistances at the different segments,the radial heat flow in the CNT bundle is calculated. The maximum percentage of the radial heat flow is less than 7% with the presence of four defective CNTs, while the resultant decrement of the effective thermal conductivity of the bundle is about 18%.The present results indicate that the radial heat flow can significantly diminish the axial heat conduction in the CNT bundles,which probably explains the smaller effective thermal conductivity in the CNT assemblies compared to that of the individual CNTs.

关键词： axial thermal conductivity carbon nanotube bundle inter-tube thermal resistance radial heat flow

轻质点阵超结构设计及多功能力学性能调控方法

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力学进展 2022年第3期52卷 673-718页

作者：吴文旺夏热上海交通大学海洋工程国家重点实验室上海200240 上海交通大学船舶海洋与建筑工程学院工程力学系上海200240 武汉大学水力机械过渡过程教育部重点实验室武汉430072

随着先进制造技术、多学科交叉和人工智能科技的飞速发展,高端装备呈现出轻量化、集成化、复合化、功能化、智能化、柔性化和仿生化等发展趋势.传统结构研究存在结构设计和制造相互分离,复杂结构制造效率低、实际制造结构的性能指标和... 详细信息

随着先进制造技术、多学科交叉和人工智能科技的飞速发展,高端装备呈现出轻量化、集成化、复合化、功能化、智能化、柔性化和仿生化等发展趋势.传统结构研究存在结构设计和制造相互分离,复杂结构制造效率低、实际制造结构的性能指标和使用可靠性大幅低于设计理论预测、结构多功能一体化程度不足、经济成本过高等问题.此外,先进工业装备对材料、结构的使用性能、使用环境要求越来越高,亟需开展结构的设计、制造、功能、应用一体化研究,为解决我国先进制造“卡脖子”技术难题提供理论依据和技术支持.轻量化多功能点阵超结构具有轻质高强、抗冲击吸能、减振降噪等性能优势,在航空航天、交通运输、国防、生物医疗、能源、机械等工业领域具有巨大的应用潜力.有鉴于此,受多晶体微结构的多尺度力学设计启发,以“点阵超结构力学设计”为主题,开展点阵超结构的节点、杆件组元,胞元类型、双相结构、梯度结构、多层级结构等典型点阵超结构的几何构筑和力学设计,并阐明多晶体多尺度微观结构启发的点阵超结构力学设计基本原理、多功能力学性能调控方法,以及点阵超结构在不同类型载荷下的结构变形和失效物理机理.

关键词：多功能一体化点阵超结构力学性能多晶体微结构

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Large-area, kirigami topology structure-induced highly stretchable and flexible interconnects: Directly printing preparation and mechanic mechanism

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Science China Materials 2019年第10期62卷 1412-1422页

作者： Xuan Li xiaoli Ruan Weijing Yao Li Liu Bin Tian Huanjun Wang Yu Feng re xia Wei Wu Laboratory of Printable Functional Nanomaterials and Printed Electronics School of Printing and PackagingWuhan UniversityWuhan 430072China Key Laboratory of Hydraulic Machinery Transients School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China Shenzhen research Institute of Wuhan University Shenzhen 518057China

Integrating the topology design and printing method offers a promising methodology to realize large stretchability for ***,eco-friendly and waterbased Ag nanowires(NWs)inks were formulated and used for screen-printing highly stretchable and flexible interconnects on a large area(more than 335 mm x 175 mm).The stretchability of the interconnects was realized by introducing kirigami topology *** topology designed models were established to simulate the influence of kirigami patterns on wire compliance and to estimate the maximum stretchability via finite element analysis(FEA).The mechanic mechanism results demonstrate that an increase of the wave numbers results in larger stretchability,and the rectangular type of wave shows better stretchability than the zigzag and sine ***,the electrical and mechanical properties of the interconnects were measured and analyzed,and the experimental results were consistent with *** electric conductivity of the interconnects is stable at^10,427 S cm-1 even after 1000 cycles of 15.83 mm radius bending,280%stretching and 200%twisting-stretching deformation,demonstrating outstanding mechanical reliability of the *** topology designed interconnects have been applied in stretchable flexible light-emitting diode,indicating their broad application prospects in next-generation stretchable electronics.

关键词： screen printing stretchable and flexible conductors finite element analysis printed electronics