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Effect of boundary conditions on shakedown analysis of heterogeneous materials

Applied Mathematics and mechanics(English Edition) 2024年第1期45卷 39-68页

作者： Xiuchen GONG Yinghao NIE Gengdong CHENG Kai LI State Key laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentInternational Research Center for Computational MechanicsDepartment of Engineering MechanicsDalian University of TechnologyDalian 116023Liaoning ProvinceChina

The determination of the ultimate load-bearing capacity of structures made of elastoplastic heterogeneous materials under varying loads is of great importance for engineering analysis and design. Therefore, it is necessary to accurately predict the shakedown domains of these materials. The static shakedown theorem, also known as Melan's theorem, is a fundamental method used to predict the shakedown domains of structures and materials. Within this method, a key aspect lies in the construction and application of an appropriate self-equilibrium stress field(SSF). In the structural shakedown analysis, the SSF is typically constructed by governing equations that satisfy no external force(NEF) boundary conditions. However, we discover that directly applying these governing equations is not suitable for the shakedown analysis of heterogeneous materials. Researchers must consider the requirements imposed by the Hill-Mandel condition for boundary conditions and the physical significance of representative volume elements(RVEs). This paper addresses this issue and demonstrates that the sizes of SSFs vary under different boundary conditions, such as uniform displacement boundary conditions(DBCs), uniform traction boundary conditions(TBCs), and periodic boundary conditions(PBCs). As a result, significant discrepancies arise in the predicted shakedown domain sizes of heterogeneous materials. Built on the demonstrated relationship between SSFs under different boundary conditions, this study explores the conservative relationships among different shakedown domains, and provides proof of the relationship between the elastic limit(EL) factors and the shakedown loading factors under the loading domain of two load vertices. By utilizing numerical examples, we highlight the conservatism present in certain results reported in the existing literature. Among the investigated boundary conditions, the obtained shakedown domain is the most conservative under ***, utilizing PBCs to

关键词： heterogeneous material self-equilibrium stress field(SSF) shakedown analysis effect of boundary conditions

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Manipulating fast Li_(2)S redox via carbon confinement and oxygen defect engineering of In_(2)O_(3)for lithium-sulfur batteries

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Nano Research 2024年第6期17卷 5179-5187页

作者： Jinlei Qin Rui Wang Zilong Yuan Pei Xiao Deli Wang Key laboratory of Material Chemistry for Energy Conversion and Storage Ministry of EducationHubei Key Laboratory of Material Chemistry and Service FailureSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Lithium-sulfur(Li-S)batteries have been considered as promising energy storage systems due to the merits of high energy density and low ***,the lithium polysulfides(LiPSs)diffusion and sluggish redox kinetics hamper t... 详细信息

关键词： Li-S batteries nitrogen-doped carbon confinement oxygen vacancies bidirectional Li_(2)S redox

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Dynamic analysis of a novel multilink-spring mechanism for vibration isolation and energy harvesting

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Chinese Physics B 2024年第5期33卷 366-379页

作者：谢佳衡杨涛唐介 Research & Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Department of Engineering mechanics Northwest Polytechnical UniversityXi'an 710072China Applied mechanics and Structure Safety Key laboratory of Sichuan Province School of Mechanics and AerospaceSouthwest Jiaotong UniversityChengdu 610031China

Due to technical limitations,existing vibration isolation and energy harvesting(VIEH)devices have poor performance at low *** paper proposes a new multilink-spring mechanism(MLSM)that can be used to solve this *** VIEH performance of the MLSM under harmonic excitation and Gaussian white noise was *** was found that the MLSM has good vibration isolation performance for low-frequency isolation and the frequency band can be widened by adjusting parameters to achieve a higher energy harvesting *** comparison with two special cases,the results show that the MLSM is basically the same as the other two oscillators in terms of vibration isolation but has better energy harvesting performance under multistable *** MLSM is expected to reduce the impact of vibration on high-precision sensitive equipment in some special sites such as subways and mines,and at the same time supply power to structural health monitoring devices.

关键词： multilink-spring mechanism nonlinear dynamics vibration isolation energy harvester

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Influence of Bottom Inclination on the Flow Structure in a Rotating Convective Layer

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Fluid Dynamics & Materials Processing 2024年第4期20卷 739-748页

作者： Andrei Vasiliev Andrei Sukhanovskii Elena Popova laboratory of Turbulence Institute of Continuous Media Mechanics UB RASPerm614013Russia

The formation of convective flows in a rotating cylindrical layer with an inclined bottom and free surface is *** is driven by localized cooling at the center of the upper free surface and by rim heating at the bottom near the *** horizontal temperature difference in a rotating layer leads to the formation of a convective flow with a complex *** mean meridional circulation,consisting of three cells,provides a strongly non-uniform differential *** a result of the instability of the main cyclonic zonal flow,the train of baroclinic waves appears in the upper *** baroclinic waves provide most of the heat transfer in the middle radii and are responsible for strong temperature and velocity *** is shown that the inclination of the bottom is a crucial factor for the structure of the convective cells and the dynamics of the baroclinic *** increase in the inclination angle leads to a significant increase in the energy of the *** obtained results may be important for heat and mass transfer in various geophysical and industrial systems,including transport of various additives and impurities in rotating crucibles,and crystallization processes.

关键词： laboratory modeling global atmospheric circulation baroclinic waves beta-effect

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The Disintegration of a Floating Ferrofluid Layer into an Ordered Drop System in a Vertical Magnetic Field

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Fluid Dynamics & Materials Processing 2024年第10期20卷 2205-2218页

作者： Christina Khokhryakova Konstantin Kostarev Irina Mizeva laboratory of Dispersed System Dynamics Institute of Continuous Media Mechanics UrB RASPerm614018Russia laboratory of Hydrodynamical Stability Institute of Continuous Media Mechanics UrB RASPerm614018Russia laboratory of Turbulence Institute of Continuous Media Mechanics UrB RASPerm614018Russia

Magnetic fluids,also known as ferrofluids,are versatile functional materials with a wide range of *** applications span from industrial uses such as vacuum seals,actuators,and acoustic devices to medical uses,including serving as contrast agents for magnetic resonance imaging(MRI),delivering medications to specific locations within the body,and magnetic hyperthermia for cancer *** use of a non-wettable immiscible liquid substrate to support a layer of magnetic fluid opens up new possibilities for studying various fluid flows and related instabilities in multi-phase systems with both a free surface and an *** presence of two deformable boundaries within a ferrofluid layer significantly reduces the critical magnetic field strength required to transform the layer into an organized system of drops or polygonal figures evolving according to the intensity,frequency and direction of the considered magnetic *** paper experimentally investigates this problem by assuming a uniform magnetic field perpendicular to the *** specific subject has not been previously explored *** critical magnetic field intensity required to destabilize the ferrofluid layer is determined based on the layer’s thickness and the fluid’s initial magnetic *** is demonstrated that the critical magnetic field strength needed to disrupt the initially continuous ferrofluid layer increases with the layer’s ***,an increase in the ferrofluid’s magnetic susceptibility results in a decrease in the critical magnetic field *** emerging droplet structures are analyzed in terms of the number of drops,their size,and the periodicity of their *** number of droplets formed depends on the initial thickness of the layer,the presence or absence of a stable rupture in the upper layer,and the rate at which the magnetic field strength is increased to the critical value.A characteristic viscous time is proposed

关键词： Ferrofluid liquid substrate normal field instability ordered droplet structure

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The influence of stress-dependent overpotential on dendrite growth in all-solid-state battery with cracks

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Science China(Technological Sciences) 2024年第8期67卷 2493-2504页

作者： ZHANG ZhenHua ZHANG Yong LIU Chang HOU Xu WANG Jie Department of Engineering mechanics School of Aeronautics and AstronauticsZhejiang UniversityHangzhou 310027China Zhejiang laboratory Hangzhou 311100China Key laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang UniversityHangzhou 310027China School of Aerospace Engineering and Applied mechanics Tongji UniversityShanghai 200092China Applied mechanics and Structure Safety Key laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

Dendrite growth is one of the main challenges in maintaining the service life of all-solid-state lithium-ion *** stress has been reported to significantly affect dendrite *** this study,to explain the effect of mechanical stress on electrochemical reactions in all-solid-state batteries,a modified phase-field model for dendrite growth is proposed by considering the stress-dependent *** growth under different mechanical loadings in an all-solid-state battery is investigated using the proposed *** with previous experimental results,the current result shows that compressive stress inhibits dendrite *** the stress concentration at the tips of processing-induced microcracks,the effects of the number and distribution of microcracks on dendrite growth are *** results show that the stress-concentration field induced at the tips of cracks or voids can change the morphology of dendrites and decrease their growth *** study provides a new perspective for explaining Li dendrite growth under mechanical stress and offers inspiration for prolonging the service life of all-solid-state batteries based on defect and stress regulation,which may be further realized in experiments by filling solid electrolytes with different types of nanofillers.

关键词： Butler–Volmer equation stress-dependent overpotential microcracks all-solid-state battery phase-field simulation

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Experimental Study on Mixed-Mode(Ⅰ–Ⅱ)Fracture Toughness of Freshwater Ice

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Acta Mechanica Solida Sinica 2024年第2期37卷 252-264页

作者： Yaozhong Xu Mao Zhou Xian Yi Wen Hua Jiuzhou Huang Wenyu Zhang Shiming Dong Key laboratory of Deep Underground Science and Engineering Ministry of EducationCollege of Architecture and EnvironmentSichuan UniversityChengdu610065China failure mechanics and Engineering Disaster Prevention Key laboratory of Sichuan Province Sichuan UniversityChengdu610065China China Aerodynamics Research and Development Center/Low Speed Aerodynamics Research Institute Mianyang621000China College of Mechanical and Electrical Engineering Xichang UniversityXichang615000China

In recent years,the issue of aircraft icing has gained widespread *** breaking and detachment of dynamic ice can pose a threat to flight ***,the shedding and fracture mechanisms of dynamic ice are unclear and cannot meet the engineering needs of ice-shedding hazard ***,studying the fracture toughness of ice bodies has extremely important practical *** address this issue,this article uses a centrally cracked Brazilian disk(CCBD)specimen to measure the pure modeⅠtoughness and pure modeⅡfracture toughness of freshwater ice at different loading *** mixed-mode(Ⅰ–Ⅱ)fracture characteristics of ice are discussed,and the experimental results are compared and analyzed with the theoretical values of the generalized maximum tangential stress(GMTS)criterion considering the influence of *** results indicated that as the loading rate increases,the pure modeⅠtoughness and pure modeⅡfracture toughness of freshwater ice decrease,and the fracture toughness of freshwater ice is more sensitive to the loading rate.Ⅰn terms of fracture criteria,the theoretical value of the ratio of pure modeⅡfracture toughness to pure modeⅠfracture toughness based on the GMTS criterion is in good agreement with the experimental value,while the theoretical value based on the maximum tangential stress(MTS)criterion deviates significantly from the experimental value,indicating that the GMTS criterion considering the influence of T-stress can better predict the experimental results.

关键词： Freshwater ice Fracture criteria Centrally cracked Brazilian disk(CCBD) Mixed-mode(Ⅰ-Ⅱ) Loading rate

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Elastic wave insulation and propagation control based on the programmable curved-beam periodic structure

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Applied Mathematics and mechanics(English Edition) 2024年第10期45卷 1791-1806页

作者： Jiajia MAO Hong CHENG Tianxue MA Beijing Key laboratory of Nonlinear Vibrations and Strength of Mechanical Structures Department of MechanicsSchool of MathematicsStatistics and MechanicsBeijing University of TechnologyBeijing 100124China Department of mechanics School of Physical Science and EngineeringBeijing Jiaotong UniversityBeijing 100044China

Curved-beams can be used to design modular multistable metamaterials(MMMs)with reprogrammable material properties,i.e.,programmable curved-beam periodic structure(PCBPS),which is promising for controlling the elastic wave *** PCBPS is theoretically equivalent to a spring-oscillator system to investigate the mechanism of bandgap,analyze the wave propagation mechanisms,and further form its geometrical and physical criteria for tuning the elastic wave *** the equivalent model,we calculate the analytical solutions of the dispersion relations to demonstrate its adjustability,and investigate the wave propagation characteristics through the *** validate the equivalent system,the finite element method(FEM)is *** is revealed that the bandgaps of the PCBPS can be turned on-and-off and shifted by varying its physical and geometrical *** findings are highly promising for advancing the practical application of periodic structures in wave insulation and propagation control.

关键词： curved-beam based periodic structure equivalent stiffness spring-oscillator system dispersion relation wave propagation

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Indentation behavior of a semi-infinite piezoelectric semiconductor under a rigid flat-ended cylindrical indenter

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Applied Mathematics and mechanics(English Edition) 2024年第4期45卷 649-662页

作者： Shijing GAO Lele ZHANG Jinxi LIU Guoquan NIE Weiqiu CHEN State Key laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China Hebei Key laboratory for mechanics of Intelligent Materials and Structures Department of Engineering MechanicsShijiazhuang Tiedao UniversityShijiazhuang 050043China State Key laboratory of Computer Aided Design and Computer Graphics Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering MechanicsZhejiang UniversityHangzhou 310027China

This paper theoretically studies the axisymmetric frictionless indentation of a transversely isotropic piezoelectric semiconductor(PSC)half-space subject to a rigid flatended cylindrical *** contact area and other surface of the PSC half-space are assumed to be electrically *** the Hankel integral transformation,the problem is reduced to the Fredholm integral equation of the second *** equation is solved numerically to obtain the indentation behaviors of the PSC half-space,mainly including the indentation force-depth relation and the electric potential-depth *** results show that the effect of the semiconductor property on the indentation responses is limited within a certain range of variation of the steady carrier *** dependence of indentation behavior on material properties is also analyzed by two different kinds of *** element simulations are conducted to verify the results calculated by the integral equation technique,and good agreement is demonstrated.

关键词： piezoelectric semiconductor(PSC) insulating indenter electromechanical response singular integral equation finite element simulation

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Theoretical and experimental study of a bi-stable piezoelectric energy harvester under hybrid galloping and band-limited random excitations

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Applied Mathematics and mechanics(English Edition) 2024年第3期45卷 461-478页

作者： Haitao LI Tianyu ZHENG Weiyang QIN Ruilan TIAN Hu DING J.C.JI Liqun CHEN Department of Engineering mechanics North University of ChinaTaiyuan 030051China Department of Engineering mechanics Northwestern Polytechnical UniversityXi'an 710072China Department of Engineering mechanics Shijiazhuang Tiedao UniversityShijiazhuang 050043China Shanghai Key laboratory of mechanics in Energy Engineering Shanghai Frontier Science Center of MechnoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China School of Mechanical and Mechatronic Engineering University of Technology SydneyNew South Wales 2007Australia

In the practical environment,it is very common for the simultaneous occurrence of base excitation and *** the combined energy of vibration and wind with a single energy harvesting structure is *** this purpose,the effects of the wind speed and random excitation level are investigated with the stochastic averaging method(SAM)based on the energy *** results of the analytical prediction are verified with the Monte-Carlo method(MCM).The numerical simulation shows that the introduction of wind can reduce the critical excitation level for triggering an inter-well jump and make a bi-stable energy harvester(BEH)realize the performance enhancement for a weak base ***,as the strength of the wind increases to a particular level,the influence of the random base excitation on the dynamic responses is weakened,and the system exhibits a periodic galloping response.A comparison between a BEH and a linear energy harvester(LEH)indicates that the BEH demonstrates inferior performance for high-speed *** experiments are conducted to investigate the validity of the theoretical prediction and numerical *** experimental findings also show that strong random excitation is favorable for the BEH in the range of low wind ***,as the speed of the incoming wind is up to a particular level,the disadvantage of the BEH becomes clear and evident.

关键词： bi-stability inter-well response galloping band-limited random

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