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Microscopic strengthening and failure mechanisms of graphene/Al composite: A molecular dynamics study

Progress in Natural Science:Materials International 2024年第4期34卷 720-730页

作者： Huijuan Guo Xiaoyan Sun Liang Chen Yuhui Zhao Kaiqiang Shen Xiangshan Kong State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education) Shandong University Intelligent Manufacturing Department Yantai Engineering and Technology College

This study focused on the microscopic strengthening and failure mechanisms of the Al matrix reinforced by graphene(Gr), and the effects of number of layers, chirality, and arrangement of Gr were calculated based on the molecular dynamics simulation. The results revealed that the Young's modulus and yield strength were significantly enhanced by the addition of Gr. In Gr/Al composites with monolayer Gr, the zigzag Gr exhibited a better ultimate strain than the armchair Gr, indicating that the plastic deformation was affected by the chirality, and the dislocation hindrance and load transfer were the dominated strengthening mechanisms. The crack in the armchair Gr was limited to follow straight paths, while that in zigzag Gr extended in a petal-like manner across multiple directions. In Gr/Al composite with multilayer Gr, the dispersing Gr showed a stronger strengthening effect than the stacking Gr, and the strengthening effect increased with increasing the volume fraction of Gr. The dispersing Gr strongly hindered the movement of dislocations, while the Al matrix in the composite with stacking Gr could retard the folding of Gr. Moreover, Gr nanosheets fractured layer by layer rather than simultaneously fractured in the Gr/Al composites with multilayer Gr.

关键词： Molecular dynamics Gr/Al composites Strengthening Failure

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Performance Analysis of a Hexagon Rolling Mechanism with Single Degree of Freedom

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Journal of Mechanisms and Robotics 2025年第8期17卷 081001页

作者： Zhang, Qianqian Li, Yezhuo Yan, Shaoze Yao, Yan-An Department of Mechanical Engineering Tsinghua University Beijing100084 China School of Mechanical Electronic and Control Engineering Key Laboratory of Vehicle Advanced Manufacturing Measuring and Control Technology Beijing Jiaotong University Beijing100044 China

This article presents a comprehensive performance analysis of the step-climbing and passive rolling modes of a hexagon rolling mechanism with single-degree-of-freedom, based on its structural characteristics and the constraints of centroid stability. First, a step-climbing model, incorporating motion parameters and support distance parameters, is established by leveraging the symmetrical posture movement characteristics of the hexagon rolling mechanism. Building on this foundation, the impact of each parameter on the mechanism's step-climbing ability is thoroughly analyzed, and the maximum height achievable during step climbing is also examined. Subsequently, the existence and sufficient conditions for the hexagon rolling mechanism to achieve passive rolling are analyzed using the centroid fluctuation curve and its slope curves. The analysis results indicate that, due to its unique coupling structure design, the hexagon rolling mechanism possesses a passive rolling capability that is not available in conventional planar linkage mechanisms. Finally, the correctness of the theoretical model is validated through both simulation and prototype experiments. Copyright © 2025 by ASME.

关键词： Degrees of freedom (mechanics)

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Vibration control of the Rail Grinding Vehicle with Abrasive Belt Based on Structural Optimization and Lightweight Design

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 311-337页

作者： Wengang Fan Shuai Zhang Zhiwei Wu Yi Liu Jiangnan Yu School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Key Laboratory of Vehicle Advanced Manufacturing Measuring and Control TechnologyMinistry of EducationBeijing 100044China China Railway Materials Operation and Maintenance Technology Co. LtdBeijing 100036China

As a new grinding and maintenance technology,rail belt grinding shows significant advantages in many applications The dynamic characteristics of the rail belt grinding vehicle largely determines its grinding performance and service *** order to explore the vibration control method of the rail grinding vehicle with abrasive belt,the vibration response changes in structural optimization and lightweight design are respectively analyzed through transient response and random vibration simulations in this ***,the transient response simulation analysis of the rail grinding vehicle with abrasive belt is carried out under operating conditions and non-operating ***,the vibration control of the grinding vehicle is implemented by setting vibration isolation elements,optimizing the structure,and increasing ***,in order to further explore the dynamic characteristics of the rail grinding vehicle,the random vibration simulation analysis of the grinding vehicle is carried out under the condition of the horizontal irregularity of the American AAR6 ***,by replacing the Q235 steel frame material with 7075 aluminum alloy and LA43M magnesium alloy,both vibration control and lightweight design can be achieved *** results of transient dynamic response analysis show that the acceleration of most positions in the two working conditions exceeds the standard value in GB/T 17426-1998 *** optimizing the structure of the grinding vehicle in three ways,the average vibration acceleration of the whole car is reduced by about 55.1%from 15.6 m/s^(2) to 7.0 m/s^(2).The results of random vibration analysis show that the grinding vehicle with Q235 steel frame does not meet the safety conditions of 3σ.By changing frame material,the maximum vibration stress of the vehicle can be reduced from 240.7 MPa to 160.0 MPa and the weight of the grinding vehicle is reduced by about 21.7%from 1500 kg to 1175 *** modal analysis results indic

关键词： Vibration control Dynamic characteristics Structural optimization Lightweight design Modal analysis

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A regeneration strategy based on synchronous utilization in surface impurities of degradation nickel-rich material

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Progress in Natural Science:Materials International 2024年第4期34卷 710-719页

作者： Junfeng He Shijie Wang Peng Wei Jian Liu Yurong Ren School of Materials Science and Engineering Jiangsu Province Engineering Research Center of Intelligent Manufacturing Technology for the New Energy Vehicle Power Battery Changzhou Key Laboratory of Intelligent Manufacturing and Advanced Technology for Power Battery Changzhou University

The LiNi0.83Co0.12Mn0.05O2（Ni-rich NCM） cathode materials have been widely studied owing to their high energy density and excellent rate capability. However, Ni-rich NCM is prone to form large amounts of lithium impurities and causes structural decline, resulting in inconvenient material storage. To this end, Li4SiO4/SiO2was used as a structural regulator to eliminate the residual lithium and convert the irreversible phase. The Li4SiO4/SiO2protective coating effectively suppresses the corrosion of the electrolyte by blocking the direct contact between the electrode and the electrolyte, while having a high air stability under the hydrophobic action. In addition, SiO2has excellent corrosion resistance, which further enhances the cyclic stability of the material. The obtained regenerated NCM material displayed a great capacity of 198.6 mAh g-1at 0.3 C and long cycling stability（capacity retention of 82.2 % after 250 cycles）. This simple repair strategy significantly reduces the loss rate in industrial production and enhances the electrochemical performance while achieving material reuse.

关键词： LiNi0.83Co0.12Mn0.05O2 Structural repair Li4SiO4 SiO2 Surface coating

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Trajectory tracking control of autonomous heavy-duty mining dump trucks with uncertain dynamic characteristics

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Science China(Information Sciences) 2023年第10期66卷 246-262页

作者： Liang CHEN Zhaobo QIN Manjiang HU Hongbo GAO Yougang BIAN Biao XU Xiaoyan PENG State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Wuxi Intelligent Control Research Institute of Hunan University Department of Automation University of Science and Technology of China

The proportion of mines using autonomous mining trucks is still very low at present. To promote the development of intelligent mining, it is urgent to proceed with the drive-by-wire modification to common mining trucks and design a motion control algorithm considering uncertain dynamic *** paper proposes a trajectory tracking control method for autonomous heavy-duty mining dump trucks(AHMDTs) with uncertain dynamic characteristics. In this method, a driving/braking force compensation algorithm based on an inverse dynamic model is designed to guarantee accurate longitudinal control with less control gain tuning. Using road curvatures, a modified rear-wheel position feedback control method is proposed to deal with reverse-path tracking, which can simultaneously reduce the lateral error and yaw angle error. A modified Stanley controller considering the collaborative preview based on speed and curvature is constructed to achieve accurate path tracking in the forward gear. Moreover, the proposed method focuses on the practice of trajectory tracking control in an open-pit mine condition with the adverse effects caused by uncertain vehicle dynamics, huge variable load, and large actuator lag. Real vehicle tests show that the proposed methodology can control AHMDTs with a low tracking error.

关键词： vehicle control trajectory tracking control driving/braking force compensation rear-wheel position feedback

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Review of key technologies of climbing robots

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Frontiers of Mechanical Engineering 2023年第4期18卷 79-96页

作者： Ye DAI Shikun LI Xukun RUI Chaofang XIANG Xinlei NIE Key Laboratory of Advanced Manufacturing Intelligent Technology of Ministry of Education Harbin University of Science and TechnologyHarbin 150080China

In recent years,the robot industry has developed rapidly,and researchers and enterprises have begun to pay more attention to this *** are barely familiar with climbing robots,a kind of special ***,from their practical value and scientific research value,climbing robots should studied *** paper analyzes and summarizes the key technologies of climbing robots,introduces various kinds of climbing robots,and examines their advantages and disadvantages to provide a reference for future *** countries have studied climbing robots and made some ***,due to the complexity of climbing robots,their climbing efficiency and accuracy need to be further *** new structure can improve the climbing *** paper analyzes climbing robots such as mechanical arms,magnetic attraction,and *** methods and path planning can improve the accuracy of *** paper involves some control methods,including complex intelligent control methods such as behavior-based robot *** paper also investigates various kinematic planning methods and expounds and summarizes various path planning algorithms,including machine learning and reinforcement learning of artificial intelligence,ant colony algorithm,and other ***,by analyzing the research status of climbing robots at home and abroad,this paper summarizes three important aspects of climbing robots,namely,structural design,control methods,and climbing strategies,elaborates on the achievements and existing problems of these key technologies,and looks forward to the future development trend and research direction of climbing robots.

关键词： climbing robot mechanical structure design control system kinematics planning path planning

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Synergistic strategy of surface-induced spinel structure and F doping to improve the electrochemical performance of Li-rich cathodes

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Progress in Natural Science:Materials International 2024年第3期34卷 524-531页

作者： Yuezhen Wang Ningbo Qin Xun Yuan Shiming Qiu Fangli Ji Ruirui Tuo Tingfeng Guan Cheng Yang Jiang Zhu Miao Ge Hui Wang Yan Cheng Zhaozhe Yu Guangxi Key Laboratory of Manufacturing Systems and Advanced Manufacturing Technology Guilin University of Electronic Technology Guangxi Institute of Science and Technology Development Co. Ltd. Guangxi CNGR New Energy Science & Technology Co. Ltd. Guangxi Key Laboratory for High-value Utilization of Manganese Resources Guangxi Minzu Normal University

Li-rich Mn-based materials provide higher capacity than commercial NCM layered materials due to the synergistic redox effect of cations and anions. However, lattice straining and structural collapse caused by the irreversible oxygen release at high voltage range during cycling, which results in severe capacity and voltage decay. Herein, a synergistic strategy of surface-induced spinel structure and F doping is provided to improve the structural stability. The surface spinel structure helps to reduce the structural collapse caused by electrolyte corrosion on the cathode and effectively inhibits voltage decay resulted from structural evolution. The stronger Mn-F bonds are formed by F doping to inhibit migration of transition metal(TM) and induce the uniform deposition of Li F to form the thinner and more stable CEI on the cathode. Accordingly, the designed cathode(LMNO-NF) shows remarkable cycling performance with the capacity retention of 86.68 % and voltage retention of 96.6 % for 200 cycles at 1C,higher than pristine material(68.76 % and 85.75 %). Therefore, this simple dual-modification strategy of one-step synthesis is promising for solving the structural evolution and voltage decay of Li-rich Mn-based cathode materials effectively, achieving further commercialization.

关键词： Synergistic strategy Surface-induced spinel structure F doping High cycling stability Li-rich Mn-Based cathode

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Machinability of elliptical ultrasonic vibration millingγ-TiAl:Chip formation,edge breakage,and subsurface layer deformation

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Chinese Journal of Aeronautics 2025年第3期38卷 624-644页

作者： Ziwen XIA Chenwei SHAN Menghua ZHANG Wengang LIU Minchao CUI Ming LUO Key Laboratory of High Performance Manufacturing for Aero Engine Ministry of Industry and Information TechnologyNorthwestern Polytechnical UniversityXi’an 710072China Engineering Research Center of Advanced Manufacturing Technology for Aero Engine Ministry of EducationNorthwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Cemented Carbide Zhuzhou 412000China

Superior strength and high-temperature performance make γ-TiAl vital for lightweight aero-engines. However, its inherent brittleness poses machining problems. This study employed Elliptical Ultrasonic Vibration Milling (EUVM) to address these problems. Considering the influence of machining parameters on vibration patterns of EUVM, a separation time model was established to analyze the vibration evolutionary process, thereby instructing the cutting mechanism. On this basis, deep discussions regarding chip formation, cutting force, edge breakage, and subsurface layer deformation were conducted for EUVM and Conventional Milling (CM). Chip morphology showed the chip formation was rooted in the periodic brittle fracture. Local dimples proved that the thermal effect of high-speed cutting improved the plasticity of γ-TiAl. EUVM achieved a maximum 18.17% reduction in cutting force compared with CM. The force variation mechanism differed with changes in the cutting speed or the vibration amplitude, and its correlation with thermal softening, strain hardening, and vibratory cutting effects was analyzed. EUVM attained desirable edge breakage by achieving smaller fracture lengths. The fracture mechanisms of different phases were distinct, causing a surge in edge fracture size of γ-TiAl under microstructural differences. In terms of subsurface deformation, EUVM also showed strengthening effects. Noteworthy, the lamellar deformation patterns under the cutting removal state differed from the quasi-static, which was categorized by the orientation angles. Additionally, the electron backscattering diffraction provided details of the influence of microstructural difference on the orientation and the deformation of grains in the subsurface layer. The results demonstrate that EUVM is a promising machining method for γ-TiAl and guide further research and development of EUVM γ-TiAl.

关键词： γ-TiAl Elliptical ultrasonic vibration millingi Chip formation Edge breakage Microstructure

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Double effects of recrystallization behavior on grain morphology evolution and mechanical properties of Al/Mg/Al composite plate by hard plate rolling

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Progress in Natural Science:Materials International 2024年第5期34卷 1029-1038页

作者： Jia Yang Zhang Feng Li Fu Wei Kang Zi Yi Wang Lu Sun School of Materials Science and Chemical Engineering Harbin University of Science and Technology Key Laboratory of Advanced Manufacturing and Intelligent Technology Ministry of Education Harbin University of Science and Technology Heilongjiang Provincial Key Laboratory of Light Metal Materials Modification & Green Forming Technology Harbin University of Science and Technology

Enhancing the bonding strength, optimizing the microstructure and refining the properties represent effective strategies for the fabrication of heterogeneous composite plates. In this study, composite plates of Al/Mg/Al were fabricated through hard plate rolling(HPR) with a reduction in rolling ranging from 40 % to 80 %. The research primarily concentrates on the substrate in the influence of rolling dynamic recrystallization(DRX) behavior on the grain morphology evolution and mechanical properties of AZ31 magnesium alloy sheets during the process. The findings indicate that at a compression amount of 60 %, the composite plate exhibits an ultimate tensile strength(UTS), a maximum elongation(EL) of 12.5 %, and improved interface bonding. Comparative analysis reveals the occurrence of DRX on the Mg side, resulting in the formation of small DRXed grains being generated. With an increase in reduction, DRX is facilitated, leading to an initial rise and subsequent decline in the proportion of DRXed grains. The proliferation of fine grains hinder dislocation movement, thereby reinforcing composite ***, an elevation in the degree of recrystallization enhances the initiation of non-basal slip and enhances the plasticity of sheet metal. This study offers valuable scientific guidance and technical assistance for the production of forming high-quality Mg–Al composite plates.

关键词： Hard plate rolling Al/Mg/Al Composite plate Dynamic recrystallization Mechanical properties

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Micromagnetic study of magnetization reversal in inhomogeneous permanent magnets

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Chinese Physics B 2023年第4期32卷 646-651页

作者：杨质陈源源刘卫强李玉卿丛利颖吴琼张红国路清梅张东涛岳明 Faculty of Materials and Manufacturing Key Laboratory of Advanced Functional Materials(Ministry of Education)Beijing University of TechnologyBeijing 100124China

Macroscopic magnetic properties of magnets strongly depend on the magnetization process and the microstructure of the *** materials such as hard-soft exchange-coupled magnets or just real technical materials with impurities and inhomogeneities exhibit complex magnetization *** we investigate the effects of size,volume fraction,and surroundings of inhomogeneities on the magnetic properties of an inhomogeneous magnetic material via micromagnetic *** underlying magnetization reversal and coercivity mechanisms are *** different demagnetization characteristics corresponding to the exchange coupling phase,semi-coupled phase,and decoupled phase are found,depending on the size of *** addition,the increase in the size of inhomogeneities leads to a transition of the coercivity mechanism from nucleation to *** work could be useful for optimizing the magnetic properties of both exchange-coupled nanomagnets and inhomogeneous single-phase magnets.

关键词： permanent magnets micromagnetic simulation exchange-coupling multilayers

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