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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

Transition from grain boundary migration to grain boundary sliding in magnesium bicrystals

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Acta Mechanica Sinica 2024年第8期40卷 17-31页

作者： Zheyuan Xing Haidong Fan Chuanlong Xu Guozheng Kang School of mechanics and Aerospace engineering Southwest Jiaotong UniversityChengdu610031China department of mechanics Sichuan UniversityChengdu610065China

In polycrystalline magnesium(Mg)and Mg alloys,as the grain size decreases,the grain boundary(GB)mediated plasticity including GB sliding and GB migration becomes the dominant deformation *** this study,the motion of[1100]symmetric tilt GBs in Mg bicrystals is investigated using molecular dynamics(MD)*** effects of GB misorientation angle and temperature are *** low/room temperatures and varied GB misorientation angles in the range ofθ≥58.36°,the GB migration occurs via the shear coupling with the invariant plane of{0001};At 35.80°<θ<58.36°,both the GB migration and GB sliding happen and the invariant plane changes from{0001}plane to[1122]plane;At 26.54°≤θ≤35.80°,the GB migrates with the invariant plane of[1122];Finally,atθ<26.54°,the GB sliding becomes the main deformation *** 700 K,the GB sliding occurs at the misorientation angles in the range ofθ<58.36θ;while the GB migration occurs at the misorientation angles ofθ≥58.36°.By comparing the energy barriers of GB migration and GB sliding,it yields that the deformation mode with a low energy barrier always happens,which leads to the transition of deformation modes and agrees well with the MD simulation results.

关键词： Molecular dynamics simulations Magnesium Grain boundary migration Grain boundary sliding Temperature

Size-dependent thermomechanical vibration characteristics of rotating pre-twisted functionally graded shear deformable microbeams

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applied Mathematics and mechanics(English Edition) 2024年第6期45卷 1015-1032页

作者： Songye JIN Bo ZHANG Wuyuan ZHANG Yuxing WANG Huoming SHEN Jing WANG Juan LIU School of mechanics and Aerospace engineering Southwest Jiaotong UniversityChengdu 610031China School of Mechanical engineering Southwest Jiaotong UniversityChengdu 610031China School of Mechanical and Electrical engineering Southwest Petroleum UniversityChengdu 610500China

A three-dimensional(3D)thermomechanical vibration model is developed for rotating pre-twisted functionally graded(FG)microbeams according to the refined shear deformation theory(RSDT)and the modified couple stress theory(MCST).The material properties are assumed to follow a power-law distribution along the chordwise *** model introduces one axial stretching variable and four transverse deflection variables including two pure bending components and two pure shear *** complex modal analysis and assumed mode methods are used to solve the governing equations of motion under different boundary conditions(BCs).Several examples are presented to verify the effectiveness of the developed *** coupling the slenderness ratio,gradient index,rotation speed,and size effect with the pre-twisted angle,the effects of these factors on the thermomechanical vibration of the microbeam with different BCs are *** is found that with the increase in the pre-twisted angle,the critical slenderness ratio and gradient index corresponding to the thermal instability of the microbeam increase,while the critical material length scale parameter(MLSP)and rotation speed *** sensitivity of the fundamental frequency to temperature increases with the increasing slenderness ratio and gradient index,and decreases with the other increasing ***,the size effect can suppress the dynamic stiffening effect and enhance the Coriolis ***,the mode transition is quantitatively demonstrated by a modal assurance criterion(MAC).

关键词： thermomechanical vibration rotating pre-twisted functionally graded(FG)microbeam refined shear deformation theory(RSDT) modified couple stress theory(MCST) modal assurance criterion(MAC)

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

Novel method for measuring surface residual stress using flat-ended cylindrical indentation

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Chinese Journal of Aeronautics 2024年第8期37卷 486-495页

作者： Guangzhao HAN Lixun CAI Xiaokun LIU applied mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China Zhengzhou Machinery Research Institute Transmission Technology Co. LtdZhengzhou 518115China

Instrumented indentation is a promising technique for estimating surface residual stresses and mechanical properties in engineering *** relative difference between the indentation loads for unstressed and stressed specimens was selected as the key parameter for measuring surface residual stresses in flat-ended cylindrical *** on the equivalent material method and finite element simulations,a dimensionless mapping model with six constants was established between the relative load difference,constitutive model parameters,and normalized residual stress.A novel method for measuring the surface residual stress and constitutive model parameters of metallic material through flat-ended cylindrical indentations was proposed using this model and a mechanical properties determination *** simulations were conducted using numerous elastoplastic materials with different residual stresses to verify the proposed model;good agreements were observed between the predicted residual stresses and those previously applied in finite element ***-ended cylindrical indentation tests were performed on four metallic materials using cruciform specimens subjected to various equibiaxial *** results exhibited good conformance between the stress–strain curves obtained using the proposed method and those from traditional tensile tests,and the absolute differences between the predicted residual stresses and applied stresses were within 40 MPa in most cases.

关键词： Instrumented indentation Residual stress Finite element simulation Equivalent material method Mechanical property

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

Micropillar compression using discrete dislocation dynamics and machine learning

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Theoretical & applied mechanics Letters 2024年第1期14卷 39-47页

作者： Jin Tao Dean Wei Junshi Yu Qianhua Kan Guozheng Kang Xu Zhang School of mechanics and Aerospace engineering Southwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Nonlinear mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

Discrete dislocation dynamics(DDD)simulations reveal the evolution of dislocation structures and the interaction of *** study investigated the compression behavior of single-crystal copper micropillars using fewshot machine learning with data provided by DDD *** types of features are considered:external features comprising specimen size and loading orientation and internal features involving dislocation source length,Schmid factor,the orientation of the most easily activated dislocations and their distance from the free *** yielding stress and stress-strain curves of single-crystal copper micropillar are predicted well by incorporating both external and internal features of the sample as separate or combined *** is found that the machine learning accuracy predictions for single-crystal micropillar compression can be improved by incorporating easily activated dislocation features with external ***,the effect of easily activated dislocation on yielding is less important compared to the effects of specimen size and Schmid factor which includes information of orientation but becomes more evident in small-sized ***,incorporating internal features,especially the information of most easily activated dislocations,improves predictive capabilities across diverse sample sizes and orientations.

关键词： Discrete dislocation dynamics simulations Machine learning Size effects Orientation effects Microstructural features

Prediction of high-embankment settlement combining joint denoising technique and enhanced GWO-v-SVR method

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Journal of Rock mechanics and Geotechnical engineering 2024年第1期16卷 317-332页

作者： Qi Zhang Qian Su Zongyu Zhang Zhixing Deng De Chen School of Civil engineering Southwest Jiaotong UniversityChengduChina MOE Key Laboratory of High Speed Railway engineering Southwest Jiaotong UniversityChengduChina

Reliable long-term settlement prediction of a high embankment relates to mountain infrastructure *** study developed a novel hybrid model(NHM)that combines a joint denoising technique with an enhanced gray wolf optimizer(EGWO)-n-support vector regression(n-SVR)***-embankment field measurements were preprocessed using the joint denoising technique,which in-cludes complete ensemble empirical mode decomposition,singular value decomposition,and wavelet packet ***,high-embankment settlements were predicted using the EGWO-n-SVR *** this method,the standard gray wolf optimizer(GWO)was improved to obtain the EGWO to better tune the n-SVR model *** proposed NHM was then tested in two case ***,the influences of the data division ratio and kernel function on the EGWO-n-SVR forecasting performance and prediction efficiency were *** results indicate that the NHM suppresses noise and restores details in high-embankment field ***,the NHM out-performs other alternative prediction methods in prediction accuracy and *** demonstrates that the proposed NHM is effective in predicting high-embankment settlements with noisy field ***,the appropriate data division ratio and kernel function for EGWO-n-SVR are 7:3 and radial basis function,respectively.

关键词： High embankment Settlement prediction Joint denoising technique Enhanced gray wolf optimizer Support vector regression

Fourth-order phase-field modeling for brittle fracture in piezoelectric materials

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applied Mathematics and mechanics(English Edition) 2024年第5期45卷 837-856页

作者： Yu TAN Fan PENG Chang LIU Daiming PENG Xiangyu LI State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Science Chang'an UniversityXi'an 710064China applied mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Failure analyses of piezoelectric structures and devices are of engineering and scientific *** this paper,a fourth-order phase-field fracture model for piezoelectric solids is developed based on the Hamilton *** typical electric boundary conditions are involved in the present model to characterize the fracture behaviors in various physical situations.A staggered algorithm is used to simulate the crack *** polynomial splines over hierarchical T-meshes(PHT-splines)are adopted as the basis function,which owns the *** numerical simulations are performed to study the influence of the electric boundary conditions and the applied electric field on the fracture behaviors of piezoelectric *** electric boundary conditions may influence crack paths and fracture loads *** present research may be helpful for the reliability evaluation of the piezoelectric structure in the future applications.

关键词： isogeometric analysis(IGA) brittle fracture fourth-order phase-field model piezoelectric solid

Analytical Expression for the Atomic Friction of a Single Asperity Based on the Prandtl-Tomlinson Model

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Acta Mechanica Solida Sinica 2024年第3期37卷 416-422页

作者： Weike Yuan Yue Ding Gangfeng Wang Xinrui Niu department of engineering mechanics SVLMMLXi’an Jiaotong UniversityXi’an710049China department of Mechanical engineering City University of Hong KongHong Kong SAR999077China

The Prandtl-Tomlinson(PT)model has been widely applied to interpret the atomic friction mechanism of a single *** this study,we present an approximate explicit expression for the friction force in the one-dimensional PT model under quasi-static ***‘stick-slip’friction curves are first approximated properly by sawtooth-like lines,where the critical points before and after the‘slip’motion are described analytically in terms of a dimensionless parameterη.Following this,the average friction force is expressed in a closed form that remains continuous and valid forη>***,an analytical expression for the load dependence of atomic friction of a single asperity is derived by connecting the parameterηwith the normal *** the parameters reported in experiments,our prediction shows good agreement with relevant experimental results.

关键词： Atomic friction Stick-slip friction Prandtl-Tomlinson model Friction force microscope