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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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Advancing electrochemical drilling process via coupling of flow field and electric field in pulsating state generated by a novel tube tool

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Chinese Journal of Aeronautics 2024年第4期37卷 542-555页

作者： Liang CHENG Xiaolei CHEN Zhisen YE Yongjun ZHANG State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment Guangdong University of TechnologyGuangzhou 510006China Guangdong Key Laboratory of Advanced Manufacturing Technology of Marine Energy Equipment Guangdong University of TechnologyGuangzhou 510006China Guangzhou Key Laboratory of Nontraditional Machining and Equipment Guangdong University of TechnologyGuangzhou 510006China

This paper introduces an improvement to electrochemical drilling process by coupling flow field and electric field in pulsating state. A novel tube with half-wedged shape at the end(HW-tube) is prepared, with both sidewall and wedged part of the HW-tube insulated. Only the flat part is utilized to provide electric field for electrochemical drilling. By rotating the HW-tube, both flow field and electric field in pulsating state are generated, alternating in different positions within the inter-electrode gap(IEG). The pulsating flow field enhances the mass transfer process, while pulsating electric field disperses material dissolution process and distribution of electrolytic byproducts. Both pulsating fields are coupled at the same frequency, further enhancing the electrochemical drilling process. Simulation results indicate that both flow field and electric field in pulsating state are generated. Compared to the traditional tube, the HW-tube significantly reduces the number of residual particles in IEG, and this number is further reduced by increasing the rotation speed. Experimental results reveal that the surface quality and dimensional uniformity of small hole are improved with HW-tube. With feed rate of 2.22 mm/min, a small hole with diameter of 1.52± 0.017 mm is drilled, resulting in a surface roughness of 0.331 μm.

关键词： Small holes Electrochemical drilling Tools Pulsating flow field Pulsating electric field

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Effect of heating temperature on microstructure and properties of Ti/steel clad plates with corrugated interfaces

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Journal of Iron and Steel Research International 2024年第12期31卷 2997-3006页

作者： Ping-ju Hao Yuan-ming Liu Yi-yang Zhang Tao Wang Qing-xue Huang Zhen-guo Wang College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan030024ShanxiChina Engineering Research Center of Advanced Metal Clads Forming Technology and Equipment Ministry of EducationTaiyuan030024ShanxiChina National Key Laboratory of Metal Forming Technology and Heavy Equipment Taiyuan030024ShanxiChina

To solve the problems of severe interface oxidation at high temperature,low interface bonding strength at low temperature,and severe plate shape warping in the traditional flat rolling process for preparing Ti/steel clad plates,a new corrugated-flat rolling(CFR)process is adopted to prepare Ti/steel clad plates with corrugated *** study investiagtes the effects of different heating temperatures on the interface morphology,mechanical properties and corrosion ***/steel clad plates prepared by CFR process have a distinct corrugated three-dimensional *** diffusion range of interface elements and the thickness of solid solution diffusion layer change with different heating *** tensile-shear strength of the clad plate increases first and then decreases with the increase in heating temperature,peaking at 327 MPa at 900℃.The tensile strength is less affected by heating temperature,and the maximum tensile strength is achieved at a heating temperature of 800℃,with a value of 766 *** the fracture process of the clad plates,the steel exhibits plastic fracture characteristics,while Ti exhibits a mixture of plastic and brittle fracture *** overall corrosion resistance of Ti surface in the clad plate is *** the heating temperature increases,the polarization resistance of Ti surface decreases,the current density in the passivation zone increases,and the active sites and energy required for the formation of the passivation film decrease.

关键词： Corrugated-flat rolling Ti/steel clad plate Heating temperature Interface morphology Mechanical property Corrosion resistance

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Progress on mechanical and tribological characterization of 2D materials by AFM force spectroscopy

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Friction 2024年第12期12卷 2627-2656页

作者： Shuai WU Jie GU Ruiteng LI Yuening TANG Lingxiao GAO Cuihua AN Qibo DENG Libin ZHAO Ning HU Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology School of Mechanical EngineeringHebei University of TechnologyTianjin 300401China Advanced Equipment Research Institute Co. Ltd.of Hebei University of TechnologyTianjin 300401China Key Laboratory of Advanced Intelligent Protective Equipment Technology Ministry of EducationTianjin 300401China State Key Laboratory of Reliability and Intelligence Electrical Equipment Hebei University of TechnologyTianjin 300130China

Two-dimensional(2D)materials are potential candidates for electronic devices due to their unique structures and exceptional physical properties,making them a focal point in nanotechnology *** assessment of the mechanical and tribological properties of 2D materials is imperative to fully exploit their potential across diverse ***,their nanoscale thickness and planar nature pose significant challenges in testing and characterizing their mechanical *** the in situ characterization techniques,atomic force microscopy(AFM)has gained widespread applications in exploring the mechanical behaviour of nanomaterials,because of the easy measurement capability of nano force and displacement from the AFM ***,AFM-based force spectroscopy is a common approach for studying the mechanical and tribological properties of 2D *** review comprehensively details the methods based on normal force spectroscopy,which are utilized to test and characterize the elastic and fracture properties,adhesion,and fatigue of 2D ***,the methods using lateral force spectroscopy can characterize the interfacial properties of 2D materials,including surface friction of 2D materials,shear behaviour of interlayers as well as nanoflake-substrate *** influence of various factors,such as testing methods,external environments,and the properties of test samples,on the measured mechanical properties is also *** the end,the current challenges and issues in AFM-based measurements of mechanical and tribological properties of 2D materials are discussed,which identifies the trend in the combination of multiple methods concerning the future development of the in situ testing techniques.

关键词： two-dimensional(2D)materials atomic force microscopy(AFM) mechanical properties nanomechanical testing nanotribology

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Effect of ceramic work rolls on surface roughness of rolled SUS304 ultra-thin strips

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Journal of Iron and Steel Research International 2024年第7期31卷 1704-1718页

作者： Peng-cheng Li Tao Wang Chen-chen Zhao Qi Liu Qing-xue Huang College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024ShanxiChina Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment of Ministry of Education Taiyuan University of TechnologyTaiyuan 030024ShanxiChina National Key Laboratory of Metal Forming Technology and Heavy Equipment Taiyuan University of TechnologyTaiyuan 030024ShanxiChina

Surface morphology and roughness are important parameters of surface quality of cold-rolled ultra-thin strip *** order to study the effect of Si_(3)N_(4) ceramic work rolls on the surface roughness of SUS304 ultra-thin strip,ABAQUS finite element model calculation,3D laser profilometry,and other methods were adopted based on the physical characteristics of Si_(3)N_(4) ceramic roll and 9Cr2MoV steel roll,like anti-flattening performance and oil *** surface morphology and roughness of SUS304 ultra-thin strip rolled by different material work rolls under oil lubrication conditions were *** results showed that under the rolling force of 10 kN,the maximum flattening amount of Si_(3)N_(4) ceramic roll was reduced by 35.14%compared to that of 9Cr2MoV steel *** reduction rate of SUS304 ultra-thin strip rolled by ceramic roll was 34.19%,while that rolled by steel roll was only 22%;Si_(3)N_(4) ceramic roll can further increase the number of alternating convex peaks and concave valleys in the rolled thin strip,reduce the profile steepness,reduce surface roughness,and enhance the planarization effect of surface micro-convex bodies,with improving surface quality and surface ***,the mechanism of Si_(3)N_(4) ceramic roll significantly improving the surface roughness of rolled SUS304 ultra-thin strip was proposed.

关键词： Ceramic work roll-Steel roll SUS304 ultra-thin strip Reduction Surface roughness

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Dynamics of electron transfer and coupling between charging and discharging in triboelectrification between insulators

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Friction 2025年第2期13卷 63-71页

作者： Wei Li Lei Zhu Liran Ma Xuefeng Xu School of Technology Beijing Forestry UniversityBeijing 100083China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

Although triboelectrification(TE)is essential in many industrial and scientific fields,its charge transfer mechanisms are still not fully *** this paper,the charging-induced electric potential on the friction surface and the discharging-induced light emission from the contact region during sliding frictions between insulators have been observed *** results show that,in the absence of discharging,the temporal variations of surface potential at all the contact points are almost the same,experiencing a rapid growth in the initial stage,followed by a slow growth,and eventually reaching a stable *** explain such a dynamics of electron transfer,a theoretical expression for the temporal evolution of the surface potential during TE process is proposed by considering the electron transfer as the charging process of a capacitor formed by contacting surfaces,and is found consistent with the experimental *** experiments further indicate that,when discharging occurs,it has no influence on the charging process of the initially negatively charged surface,but can greatly change the charging of the initially positively charged surface,on which the potential will increase initially,soon begin to decrease,and eventually reach a stable *** a significant difference in the potential variation when discharging occurs can be attributed to the huge difference in mass between electrons and positive ions produced in the discharging *** present work may offer a new perspective for understanding the electron transfer dynamics in TE and may provide potential applications in numerous fields involving TE.

关键词： triboelectrification(TE) electron transfer dynamics discharging capacitor model

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Design and Control of a Musculoskeletal Bionic Leg With Optimized and Sensorized Soft Artificial Muscles

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IEEE Transactions on Robotics 2025年 41卷 3402-3422页

作者： Dong, Xuguang Wang, Yixin Zhou, Jingyi An, Xin Zhu, Yinglei Xie, Fugui Liu, Xin-Jun Zhao, Huichan Tsinghua University Department of Mechanical Engineering State Key Laboratory of Tribology in Advanced Equipment Beijing Key Laboratory of Transformative High-end Manufacturing Equipment and Technology Beijing100084 China

The development of high-performance bionic legged robots can benefit from the continued advancements in various actuation methods, such as artificial muscles. This work presents a musculoskeletal bionic leg driven by fluidic elastomer actuators (FEAs), showcasing their potential as artificial muscles for legged robots. Our approach integrates three key innovations: First, we established a mechanics model using thin plate theory to optimize the bellows shell structure of the FEAs, achieving high force output while maintaining inherent compliance. Second, we developed a lightweight embedded optoelectronic sensing system that enables closed-loop control without significantly increasing mass. Third, we designed a two-joint leg in the sagittal plane that utilizes a bionic configuration incorporating both monoarticular and biarticular FEAs. The leg demonstrated robust performance across various tasks including extreme positional movements, load-bearing squats supporting up to 2.45 times its body weight, vertical jumping with 147 mm ground clearance, and stable walking. Notably, our embedded sensing system successfully detected ground contact states without additional foot sensors, enabling reliable gait control while minimizing complexity and weight. The experimental results validate both the mechanical capabilities of the optimized FEAs and their controllability through embedded sensing, laying a foundation for developing full legged robots with muscle-like actuation. © 2004-2012 IEEE.

关键词： Joints (anatomy)

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In vivo whole brain photoacoustic microscopy through a transparent ultrasound transducer

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Chinese Optics Letters 2025年第2期23卷 38-43页

作者： Chen Liang Junwei Wu Hangbing Peng Ljun Deng Yiqin Lin Zhongwen Cheng Luming Zeng Xuanrong Ji Jiangxi Provincial Key Laboratory of Advanced Electronic Materials and Devices Jiangxi Science and Technology Normal University Nanchang 33038China State Key Laboratory of Precision Electronics Manufacturing Technology and Equipment Guangdong University of TechnologyGuangzhou 510006China

Brain imaging techniques provide in vivo insight into structural and functional phenotypes that are physiologically and clinically ***,most existing brain imaging techniques suffer from balancing trade-offs among the temporal and spatial resolutions as well as the field of view(FOV).Here,we proposed a high-resolution photoacoustic microscopy(PAM)system based on a transparent ultrasound transducer(TUT).The system not only retains the advantage of the fast imaging speed of pure optical scanning but also has an imaging FOV of up to 20 mm×20 mm,which can easily enable rapid imaging of the whole mouse brain in *** on experimental validation of brain injury,glioma,and cerebral hemorrhage in mice,the system has the capability to visualize the vascular structure and hemodynamic changes in the cerebral ***-based PAM provides an important research tool for rapid multi-parametric brain imaging in small animals,providing a solid foundation for the study of brain diseases.

关键词： photoacoustic microscopy transparent ultrasound transducer whole brain imaging.

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Low friction under ultrahigh contact pressure enabled by self-assembled fluorinated azobenzene layers

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Friction 2024年第7期12卷 1434-1448页

作者： Dandan XUE Zhi XU Linyuan GUO Wendi LUO Liran MA Yu TIAN Ming MA Qingdao ZENG Ke DENG Wenjing ZHANG Yichun XIA Shizhu WEN Jianbin LUO State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China National Center for Nanoscience and Technology Beijing 100190China

Extensive efforts have been made to pursue a low-friction state with promising applications in many fields,such as mechanical and biomedical *** which,the load capacity of the low-friction state has been considered to be crucial for industrial ***,we report a low friction under ultrahigh contact pressure by building a novel self-assembled fluorinated azobenzene layer on an atomically smooth highly-oriented pyrolytic graphite(HOPG)*** friction coefficients could be as low as 0.0005 or even lower under a contact pressure of up to 4 *** demonstrates that the low friction under ultrahigh contact pressure is attributed to molecular *** fluorination leads to effective and robust lubrication between the tip and the self-assembled layer and enhances tighter rigidity which can reduce the stress concentration in the substrate,which was verified by density functional theory(DFT)and molecular dynamics(MD)*** work provides a new approach to avoid the failure of ultralow friction coefficient under relatively high contact pressure,which has promising potential application value in the future.

关键词： ultrahigh contact pressure self-assembled layer fluorination robust lubrication

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An Iterative Tuning Method for Feedforward Control of Parallel Manipulators Considering Nonlinear Dynamics

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Chinese Journal of Mechanical Engineering 2025年第1期38卷 295-305页

作者： Xiaojian Wang Jun Wu Beijing Key Laboratory of Transformative High-end Manufacturing Equipment and Technology Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology in Advanced Equipment and Institute of Manufacturing Engineering Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

Feedforward control is one of the most effective control techniques to increase the robot’s tracking ***,most of the dynamic models used in the feedforward controllers are linearly simplified such that the nonlinear and time-varying characteristics of dynamics in the workspace are *** this paper,an iterative tuning method for feedforward control of parallel manipulators by taking nonlinear dynamics into account is *** on the robot rigid-body dynamic model,a feedforward controller considering the dynamic nonlinearity is *** iterative tuning method is given to iteratively update the feedforward controller by minimizing the root mean square(RMS)of the joint errors at each *** effectiveness and extrapolation capability of the proposed method are validated through the experiments on a 2-DOF parallel *** research proposes an iterative tuning method for feedforward control of parallel manipulators considering nonlinear dynamics,which has better extrapolation capability in the whole workspace of manipulators.

关键词： Parallel manipulator Dynamic model Feedforward control Iterative learning control Parameter design

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