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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 1115-1125页

作者： Binghui Hu Yu Lei Hang Li Ziyi Wang Chao Yu Guozheng Kang Applied mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China

The nonproportional multiaxial ratchetting of cast AZ91 magnesium (Mg) alloy was examined by performing a sequence of axial-torsional cyclic tests controlled by stress with various loading paths at room temperature (RT).The evolutionary characteristics and path dependence of multiaxial ratchetting were *** illustrate that the cast AZ91 Mg alloy exhibits considerable nonproportional additional softening during cyclic loading with multiple nonproportional multiaxial loading paths;multiaxial ratchetting presents strong path dependence,and axial ratchetting strains are larger under nonproportional loading paths than under uniaxial and proportional45°linear loading paths;multiaxial ratchetting becomes increasingly pronounced as the applied stress amplitude and axial mean stress ***,stress-strain curves show a convex and symmetrical shape in axial/torsional *** ratchetting exhibits quasi-shakedown after certain loading *** abundant experimental data obtained in this work can be used to develop a cyclic plasticity model of cast Mg alloys.

关键词： cast magnesium alloy ratchetting multiaxial loading loading path stress level

Analysis of thermal management and anti-mechanical abuse of multi-functional battery modules based on magneto-sensitive shear thickening fluid

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Applied Mathematics and mechanics(English Edition) 2024年第3期45卷 529-542页

作者： Yang XIONG Bo LU Yicheng SONG Junqian ZHANG Shanghai Key Laboratory of mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China Zhejiang Laboratory Hangzhou 311100China

Electric vehicles(EVs)have garnered significant attention as a vital driver of economic growth and environmental ***,ensuring the safety of high-energy batteries is now a top priority that cannot be overlooked during large-scale *** paper proposes an innovative active protection and cooling integrated battery module using smart materials,magneto-sensitive shear thickening fluid(MSTF),which is specifically designed to address safety threats posed by lithium-ion batteries(LIBs)exposed to harsh mechanical and environmental *** theoretical framework introduces a novel approach for harnessing the smoothed-particle hydrodynamics(SPH)methodology that incorporates the intricate interplay of non-Newtonian fluid behavior,capturing the fluid-structure coupling inherent to the *** approach is further advanced by adopting an enhanced Herschel-Bulkley(H-B)model to encapsulate the intricate rheology of the MSTF under the influence of the magnetorheological effect(MRE)and shear thickening(ST)*** simulation results show that in the case of cooling,the MSTF is an effective cooling medium for rapidly reducing the *** terms of mechanical abuse,the MSTF solidifies through actively applying the magnetic field during mechanical compression and impact within the battery module,resulting in 66%and 61.7%reductions in the maximum stress within the battery jellyroll,and 31.1%and 23%reductions in the reaction force,*** mechanism effectively lowers the risk of short-circuit *** groundbreaking concepts unveiled in this paper for active protection battery modules are anticipated to be a valuable technological breakthrough in the areas of EV safety and lightweight/integrated design.

关键词： magneto-sensitive shear thickening fluid(MSTF) battery module impact protection temperature control integrated design

Molecular Dynamics Simulations of Displacement Cascade in Ni-Based Concentrated Solid Solution Alloys

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Acta Mechanica Solida Sinica 2024年第1期37卷 82-89页

作者： Chaoquan Zhao Rongxuan Xie Chuanlong Xu Xiaobao Tian Qingyuan Wang Wentao Jiang Haidong Fan Department of mechanics Sichuan UniversityChengdu 610065China

Single-phase concentrated solid solution alloys(SP-CSAs),including high-entropy alloys,have received extensive attention due to their excellent irradiation *** this work,displacement cascade simulations are conducted using the molecular dynamics method to study the evolution of defects in Ni-based *** with pure Ni,the NiCr,NiCo,and NiCu alloys exhibit a larger number of Frankel pairs(FPs)in the thermal peak stage,but a smaller number of surviving ***,the NiFe alloy displays the opposite *** explain these different observations for NiFe and other alloys,the formation energy and migration energy of interstitials/vacancies are *** the NiFe alloy,both the formation energy and migration energy barrier are *** the other hand,in NiCr and other alloys,the formation energy of interstitials/vacancies is lower,as is the migration energy barrier of *** energy analysis agrees well with previous *** present work provides new insights into the mechanism behind the irradiation resistance of binary Ni-based SP-CSAs.

关键词： Molecular dynamics simulation Displacement cascade Point defect Ni-based concentrated solid solution alloys

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

Convection and Stratification of Temperature and Concentration

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Fluid Dynamics & Materials Processing 2024年第6期20卷 1351-1364页

作者： Alexey Fedyushkin Laboratory of Complex Fluid mechanics Ishlinsky Institute for Problems in Mechanics RASMoscow119526Russia

This study is devoted to an analysis of natural convection and the emergence of delamination in an incompressible fluid encapsulated in a closed region heated from the ***,medium and intensive modes of stationary laminar thermal and thermo-concentration convection are *** is shown that nonlinear flow features can radically change the flow structure and characteristics of heat and mass ***,the temperature and concentration segregation in the center of the square region display a non-monotonic dependence on the Grashof number(flow intensity).The formation of a nonstationary periodic structure of thermal convection in boundary layers and in the core of a convective flow in the closed region is also *** of the formation of countercurrents inside the region with the direction opposite to the main convective flow are ***,the influence of vertical and horizontal vibrations on oscillatory convection is analyzed in detail.

关键词： Natural convection stratification segregation numerical simulation vibrations

A robust implicit high-order discontinuous Galerkin method for solving compressible Navier-Stokes equations on arbitrary grids

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Acta Mechanica Sinica 2024年第8期40卷 96-119页

作者： Jia Yan Xiaoquan Yang Peifen Weng Shanghai Institute of Applied Mathematics and mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China College of Energy and Mechanical Engineering Shanghai University of Electric PowerShanghai200090China

The primary impediments impeding the implementation of high-order methods in simulating viscous flow over complex configurations are robustness and *** challenges impose significant constraints on computational efficiency,particularly in the domain of engineering *** address these concerns,this paper proposes a robust implicit high-order discontinuous Galerkin(DG)method for solving compressible Navier-Stokes(NS)equations on arbitrary *** method achieves a favorable equilibrium between computational stability and *** solve the linear system,an exact Jacobian matrix solving strategy is employed for preconditioning and matrix-vector generation in the generalized minimal residual(GMRES)*** approach mitigates numerical errors in Jacobian solution during implicit calculations and facilitates the implementation of an adaptive Courant-Friedrichs-Lewy(CFL)number increasing strategy,with the aim of improving convergence and *** further enhance the applicability of the proposed method for intricate grid distortions,all simulations are performed in the reference *** practice significantly improves the reversibility of the mass matrix in implicit calculations.A comprehensive analysis of various parameters influencing computational stability and efficiency is conducted,including CFL number,Krylov subspace size,and GMRES convergence *** computed results from a series of numerical test cases demonstrate the promising results achieved by combining the DG method,GMRES solver,exact Jacobian matrix,adaptive CFL number,and reference domain calculations in terms of robustness,convergence,and *** analysis results can serve as a reference for implicit computation in high-order calculations.

关键词： Discontinuous Galerkin method Exact Jacobian matrix GMRES solver Adaptive CFL number Reference domain High-order

Alignment of inertialess spheroidal particles in flow-structure-dominated regions of turbulent channel flow:shape effect

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Acta Mechanica Sinica 2024年第8期40卷 45-66页

作者： Zhiwen Cui Lihao Zhao Applied mechanics Laboratory Department of Engineering MechanicsTsinghua UniversityBeijing100084China Laboratory of Flexible Electronics Technology Tsinghua UniversityBeijing100084China

The alignment of elongated fibers and thin disks is known to be significantly influenced by the presence of fluid coherent structures in near-wall turbulence(Cui et al.2021).However,this earlier study is confined to the spheroids with infinitely large or small aspect ratio,and the shape effect of finite aspect ratio on the alignment is not *** current study investigates the shape-dependent alignment of inertialess spheroids in structure-dominated regions of channel *** utilizing an ensemble-averaged approach for identifying the structure-dominated regions,we analyze the eigensystem of the linear term matrix in the Jeffery equation,which is governed by both particle shape and local fluid velocity *** contrast to earlier conventional analysis based on local vorticity and strain rate,our findings demonstrate that the eigensystem of the Jeffery equation offers a convenient,effective,and universal framework for predicting the alignment behavior of inertialess spheroids in turbulent *** leveraging the eigensystem of the Jeffery equation,we uncover a diverse effect of fluid coherent structures on spheroid alignment with different particle ***,we provide explanations for both shape-independent alignments observed in vortical-core regions and shape-dependent alignments around near-wall streamwise vortices.

关键词： Non-spherical particle Direct numerical simulation Wall turbulence Particle-laden flow

Subpicosecond laser ablation behavior of a magnesium target and crater evolution:Molecular dynamics study and experimental validation

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Chinese Physics B 2024年第7期33卷 613-622页

作者：江国龙周霞 State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsFaculty of Vehicle Engineering and MechanicsDalian University of TechnologyDalian 116024China

The micro-ablation processes and morphological evolution of ablative craters on single-crystal magnesium under subpicosecond laser irradiation are investigated using molecular dynamics(MD) simulations and *** simulation results exhibit that the main failure mode of single-crystal Mg film irradiated by a low fluence and long pulse width laser is the ejection of surface atoms,which has laser-induced high ***,under high fluence and short pulse width laser irradiation,the main damage mechanism is nucleation fracture caused by stress wave reflection and superposition at the bottom of the *** addition,Mg[0001] has higher pressure sensitivity and is more prone to ablation than Mg[0001].The evolution equation of crater depth is established using multi-pulse laser ablation simulation and verified by *** results show that,under multiple pulsed laser irradiation,not only does the crater depth increase linearly with the pulse number,but also the quadratic term and constant term of the fitted crater profile curve increase linearly.

关键词： laser-material interaction molecular dynamics(MD)simulation ablation crater morphology magnesium

Crack identification in concrete, using digital image correlation and neural network

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 536-550页

作者： Jingyi WANG Dong LEI Kaiyang ZHOU Jintao HE Feipeng ZHU Pengxiang BAI College of mechanics and Materials Hohai UniversityNanjing 211100China

In engineering applications,concrete crack monitoring is very *** methods are of low efficiency,low accuracy,have poor timeliness,and are applicable in only a limited number of ***,more comprehensive detection of concrete damage under different scenarios is of high value for practical engineering *** image correlation(DIC)technology can provide a large amount of experimental data,and neural network(NN)can process very rich ***,NN,including convolutional neural networks(CNN)and back propagation neural networks(BP),can be combined with DIC technology to analyze experimental data of three-point bending of plain concrete and four-point bending of reinforced *** addition,strain parameters can be used for training,and displacement parameters can be added for comprehensive *** data obtained by DIC technology are grouped for training,and the recognition results of NN show that the combination of strain and displacement parameters,i.e.,the response of specimen surface and whole body,can make results more objective and *** identification results obtained by CNN and BP show that these technologies can accurately identify *** identification results for reinforced concrete specimens are less affected by noise than those of plain concrete *** is more convenient because it can identify some features directly from images,recognizing the cracks formed by macro *** can issue early warning of the microscopic cracks,but it requires a large amount of data and *** can be seen that CNN is more intuitive and efficient in image processing,and is suitable when low accuracy is adequate,while BP is suitable for occasions with greater accuracy *** two tools have advantages in different situations,and together they can play an important role in engineering monitoring.

关键词： digital image correlation convolutional neural network back propagation neural neural network damage detection concrete

A viscoelastic metamaterial beam for integrated vibration isolation and energy harvesting

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Applied Mathematics and mechanics(English Edition) 2024年第7期45卷 1243-1260页

作者： Long ZHAO Zeqi LU Hu DING Liqun CHEN Shanghai Institute of Applied Mathematics and mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai Frontier Science Center of MechanoinformaticsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China School of Microelectronics Shanghai UniversityShanghai201800China

Locally resonant metamaterials have low-frequency band gaps and the capability of converging vibratory energy in the band gaps at resonant *** has been demonstrated by several researchers that the dissipatioin of vibratory energy within the band gap can be improved by using viscoelastic *** paper designs an integrated viscoelastic metamaterial for energy harvesting and vibration *** viscoelastic metamaterial is achieved by a viscoelastic beam periodically arrayed with spatial ball-pendulum nonlinear energy *** nonlinear resonator with an energy harvesting function is achieved by placing a free-rolling magnetic ball in a spherical cavity with an additional induction *** dynamic equations of viscoelastic metamaterials under transverse excitation are established,and the energy harvesting and vibration isolation characteristics within the dispersion relation of viscoelastic metamaterials are *** results show that the vibrations of the main body of the viscoelastic metamaterial beam are significantly suppressed in the frequency range of the local resonance band *** the same time,the elastic waves are limited in the nonlinear resonator with an energy harvesting function,which improves the energy ***,an experimental platform of viscoelastic metamaterial vibration is established for validation purposes.

关键词： viscoelastic metamaterial nonlinear vibration vibration isolation energy harvesting