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Molecular dynamics simulations of microstructure and dislocation evolution of single-crystal Ni-based superalloys under femtosecond laser loading

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Progress in Natural Science:Materials International 2024年第5期34卷 942-954页

作者： Peng Shen Xuesong Mei Tao Sun Xueshi Zhuo Xiaomao Sun Wenjun Wang Jianlei Cui Zhengjie Fan School of Mechanical Engineering Xi'an Jiaotong University State Key Laboratory for Manufacturing System Engineering Xi'an Jiaotong University Shaanxi Key Laboratory of Intelligent Robots Xi'an Jiaotong University

In this paper, molecular dynamics simulations are employed to investigate the temperature, stress distribution, microstructure and evolution of dislocations in singlecrystal Ni-based superalloys during femtosecond laser drilling of micro-holes. The results indicate that the temperature and stress variations in the model system increase with the increment of laser energy density. The pulse width has a relatively low effect on temperature and stress variations. At the same time, an increase in dislocations is primarily related to energy density and stress distribution. The number of dislocations increases with the energy density, with the 1/6<112> dislocation showing the highest increase ratio. The densest concentration of dislocations occurs at the hole walls. Dislocations and stacking faults gradually penetrate the precipitate phase under the influence of temperature and reach a stable state as the relaxation time increases. The above research findings provide important theoretical guidance for understanding the microstructure evolution and changes in the mechanical properties of single-crystal Ni-based superalloys during femtosecond laser processing of micro-holes.

关键词： Molecular dynamics

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Transfer film effects induced by 3D-printed polyether-ether-ketone with excellent tribological properties for joint prosthesis

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Bio-Design and manufacturing 2024年第1期7卷 43-56页

作者： Yang Li Jibao Zheng Changning Sun Dichen Li State Key Laboratory for Manufacturing System Engineering School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710054China National Medical Products Administration(NMPA)Key Laboratory for Research and Evaluation of Additive Manufacturing Medical Devices Xi’an Jiaotong UniversityXi’an 710054China

Based on the building principle of additive manufacturing,printing orientation mainly determines the tribological properties of joint *** this study,we created a polyether-ether-ketone(PEEK)joint prosthesis using fused filament fabrication and investigated the effects of printing orientation on its tribological properties using a pin-on-plate tribometer in 25% newborn calf *** ultrahigh molecular weight polyethylene transfer film is formed on the surface of PEEK due to the mechanical capture of wear debris by the 3D-printed groove morphology,which is significantly impacted by the printing orientation of *** the printing orientation was parallel to the sliding direction of friction,the number and size of the transfer film increased due to higher steady *** transfer film protected the matrix and reduced the friction coefficient and wear rate of friction pairs by 39.13%and 74.33%,***,our findings provide a novel perspective regarding the role of printing orientation in designing knee prostheses,facilitating its practical applications.

关键词： 3D printing orientation Transfer film Tribological properties Polyether-ether-ketone Knee prosthesis

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Microscale stray grains formation in single-crystal turbine blades of Ni-based superalloys

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Journal of Materials Science & Technology 2024年第24期191卷 134-145页

作者： Fu Wang Yang Liu Qiang Yang Dexin Ma Dichen Li State Key Laboratory for Manufacturing System Engineering School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China Foundry Institute RWTH UniversityAachen 52072Germany

Microscale stray grains(MSGs),which are composed of misoriented and fragmented high-ordered dendrite arms,small-sized equiaxed grains,and columnar grains,are a novel grain defect that occurs within the shrouds of single-crystal(SC)blades made from Ni-based ***-of-the-art non-destructive testing methods are incapable of detecting this defect,resulting in a high-risk application of SC *** study aims to control this defect by systematically investigating directional solidification processing parameters,shroud dimensions,and rhenium(Re)content in the formation of MSG *** results reveal that the defect forms exclusively at the overhanging extremities of the upper shrouds on the back side of the blades that face the *** the withdrawal rate reduces the occurrence of MSG *** the shroud dimensions increase,MSG defects appear in the transition area between the downward suspended extremity of the blade shroud and the side of the blade body,as well as near the corner of the downward suspended extremity of the *** occurrence of MSG defects increases with increasing shroud *** Re content sharply decreases the formation of MSG defects.A concentration-attached Rayleigh-Taylor instability(RTI)superheating(CARTISH)model,considering solidification shrinkage,was proposed to comprehend the formation of MSG *** results based on this model are consistent with the experimentally observed distribution and degree of MSG defects under different *** control of the CARTISH is critical to managing MSG defects.

关键词： Ni-based superalloy Single-crystal blade Microscale stray grains Mechanism Numerical simulation

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DCM-based dynamic stable walking under terrain-induced time-varying disturbances for humanoid robots

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Science China(Technological Sciences) 2025年第4期68卷 105-117页

作者： Yan LUO Chao LIU Jianhua WU Zhenhua XIONG Han DING State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240China State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China

When humanoid robots attempt to walk on terrain such as shaking platforms,time-varying disturbances are introduced to the support *** abrupt changes of inclination angle can cause the robot to lose balance upon landing,presenting significant challenges for balance control *** address this issue,we propose a novel divergent component of motion(DCM)-based time-varying disturbance walking(DCM-TVDW)*** method allows the robot to walk on rugged surfaces and helps to maintain dynamic balance when subjected to large time-varying *** the DCM-TVDW control method,we first adjust the robot's center of mass and stride height to adapt to transitions between different terrain types via a variable height stabilization method,and hold these quantities constant as base *** then combine DCM with the N-step capturability *** combination allows for dynamic balance through multi-step adjustments from the initially unstable region,thereby extending the robots stability *** and experimental results demonstrate that the DCM-TVDW method enables the SJ-Bruce robot to traverse a dynamically shaking platform with an inclination angle of approximately 22°.

关键词： humanoid robot dynamic balance control capturability time-varying disturbance

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Oxidation behavior of 4774DD1 Ni-based single-crystal superalloy at 980℃ in air

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China Foundry 2024年第2期21卷 116-124页

作者： Yu Fang Ya-zhou Li Qiang Yang Qun-gong He Xiu-fang Gong Qian Duan Hai-yang Song Fu Wang Qiong-yuan Zhang Hong Zeng State Key Laboratory of Long-Life High Temperature Materials Dongfang Turbine Co.Ltd.Deyang 618000SichuanChina State Key Laboratory for Manufacturing System Engineering School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China

The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain *** phase constitution and morphology of surface oxides and the characteristics of the crosssection oxide film were analyzed by XRD,SEM and *** show that the oxidation kinetics of the 4774DD1 superalloy follows the cubic law,indicating its weak oxidation resistance at this *** the oxidation time increases,the composition of the oxide film evolves as following:One layer consisting of a bottom Al_(2)O_(3)sublayer and an upper(Al_(2)O_(3)+NiO)mixture sublayer after oxidized for 25 ***,two layers composed of an outermost small NiO discontinuous grain layer and an internal layer for 75 *** internal layer is consisted of the bottom Al_(2)O_(3)sublayer,an intermediate narrow CrTaO_(4)sublayer,and an upper(Al_(2)O_(3)+NiO)mixture *** two layers comprising an outermost relative continuous NiO layer with large grain size and an internal layer as the oxidation time increases to 125 *** internal layer is composed of the upper(Al_(2)O_(3)+NiO)mixture sublayer,an intermediate continuous(CrTaO_(4)+NiWO_(4))mixture sublayer,and a bottom Al_(2)O_(3)***,three layers consisting of an outermost(NiAl2O_(4)+NiCr2O_(4))mixture layer,an intermediate(CrTaO_(4)+NiWO_(4))mixture layer,and a bottom Al_(2)O_(3)layer for 200 h.

关键词： nickel-base single crystal superalloy oxidation kinetics oxide film microstructure mechanism

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A novel method of suppressing machining vibration in robotic milling using magneto-rheological foam damper

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Chinese Journal of Aeronautics 2024年第12期37卷 522-543页

作者： Bo LI Chenxin SU Wei ZHAO Shengli SONG Wei TIAN Wenhe LIAO College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Intelligent Manufacturing System Technology Beijing 100854China

Owing to their remarkable flexibility and favorable cost-effectiveness,industrial robots have found extensive applications to cutting of materials across sophisticated manufacturing ***,the structurally low rigidity of these robots renders the tool tip prone to substantial oscillations during machining processes,significantly impacting product fabrication *** objective of this study is to present a novel methodology employing magnetorheological dampers for mitigating vibrations during robotic milling ***,a new type of ring nested Magneto-Rheological Foam Damper(MRFD)working in the squeeze mode is ***,the MRFD’s structure is designed considering the vibrational characteristics of robotic ***,a damping force model of the MRFD is *** feasibility of the MRFD’s structural design is validated by the finite element analyses,which is instrumental in comprehending the influence of structural parameters on the electromagnetic characteristics of the ***,a prototype of the MRFD is fabricated selecting appropriate ***,a series of excitation and milling experiments are conducted on a KUKA KR500 *** outcomes demonstrate a substantial reduction(37%-69%)in radial vibration amplitude at the tool tip during robotic milling,highlighting the effectiveness of the developed *** research endeavor has introduced a pioneering avenue and framework for vibration control in robotic milling,offering a novel paradigm for enhancing the precision of robotic machining.

关键词： Industrial robots Machining vibration Magneto-rheological dampers Robotic milling Vibration suppression

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Robotic mobile and mirror milling of large-scale complex structures

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National Science Review 2023年第5期10卷 10-13页

作者： Zenghui Xie Fugui Xie Limin Zhu Xin-Jun Liu State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical Engineering(DME) Tsinghua University Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua University State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong University

Large-scale complex structures,such as spacecraft cabins,aircraft composite skins and launch vehicle fuel tanks,are the core components of the equipment in aerospace,energy,shipbuilding and other *** milling quality and efficiency are factors directly affecting the performance and productivity of spacecraft,aircraft and other key *** kind of structure generally features large dimension,high accuracy,

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Nonlinear impedance control with trajectory adaptation for collaborative robotic grinding

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Science China(Technological Sciences) 2023年第7期66卷 1928-1936页

作者： HAN FengTao TAM SikYuen CAO ZhiHong ZHAO XingWei TAO Bo DING Han State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Intelligent Manufacturing System Technology for Complex Products Beijing Institute of Electronic System EngineeringBeijing 100854China ROKAE(Beijing)Technology Co. Ltd.Beijing 100193China

Stiffness adjustment is an important feature of human arm *** adaptive variable impedance control can adapt to the robotic stiffness,but may result in a large *** this paper,nonlinear impedance control is proposed for collaborative robotic grinding,where nonlinear force feedback is designed to compensate for the nonlinear stiffness of the ***,the interaction system can be linearization to ensure the system ***,a target trajectory adaptation strategy is studied to ensure the force tracking ***,switching law between trajectory tracking and force tracking is proposed when the robot performs a complex grinding *** stability of the switch control as well as the trajectory adaptation law is *** are conducted in a robotic grinding test rig,where the robot is used to grind a turbine *** results show that the nonlinear impedance control can obtain stable grinding force,and have better grinding quality than the linear impedance control.

关键词： impedance control robotic grinding trajectory adaptation force tracking

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Femtosecond laser fabrication of 3D vertically aligned micro-pore network on thick-film Li_(4)Ti_(5)O_(12)electrode for high-performance lithium storage

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Journal of Energy Chemistry 2024年第8期95卷 250-262,I0006页

作者： Quansheng Li Xiaofei Sun Xuesong Mei Lingzhi Wang Minxing Yang Jianlei Cui Wenjun Wang State Key Laboratory for Manufacturing System Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina Shaanxi Key Laboratory of Intelligent Robots Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina

The development of energy storage devices with high energy density relies heavily on thick film electrodes,but it is challenging due to the limited ion transport kinetics inherent in thick ***,we report on the preparation of a directional vertical array of micro-porous transport networks on LTO electrodes using a femtosecond laser processing strategy,enabling directional ion rapid transport and achieving good electrochemical performance in thick film *** three-dimensional(3D)vertically aligned micro-pore networks are innovatively designed,and the structure,kinetics characteristics,and electrochemical performance of the prepared ion transport channels are analyzed and discussed by multiple characterization and testing ***,the rational mechanisms of electrode performance improvement are studied experimentally and simulated from two aspects of structural mechanics and transmission *** ion diffusion coefficient,rate performance at 60 C,and electrode interface area of the laser-optimized 60-15%micro-porous transport network electrodes increase by 25.2 times,2.2 times,and 2.15 times,respectively than those of untreated ***,the preparation of 3D micro-porous transport networks by femtosecond laser on ultra-thick electrodes is a feasible way to develop high-energy *** addition,the unique micro-porous transport network structure can be widely extended to design and explore other high-performance energy materials.

关键词： Femtosecond laser Micro-porous transport networks Laser processing Thick film electrodes Ion transport kinetics

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A Cyclic Constitutive Model Based on Crystal Plasticity for Body-Centered Cubic Cyclic Softening Metals

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Acta Mechanica Solida Sinica 2024年第1期37卷 33-42页

作者： Xuehong Ren Wenjie Zhao Shaopu Yang Guilin Wen State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China School of Mechanical Engineering Tianjin Sino-German University of Applied SciencesTianjin 300350China State Key Laboratory of Mechanical Behavior in Traffic Engineering Structure and System Safety Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Under the framework of the small deformation crystal plasticity theory,a crystal plastic cyclic constitutive model for body-centered cubic(BCC)cyclic softening polycrystalline metals is *** constitutive model introduces the isotropic softening rule that includes two different mechanisms:namely softening under monotonic deformation and softening under cyclic deformation on each slip ***,a modified Armstrong-Frederick nonlinear kinematic hardening rule is *** appropriate explicit scale transition rule is selected to extend the single crystal constitutive model to the polycrystalline constitutive *** the model is used to predict the uniaxial and multiaxial ratcheting deformation of BCC axle steel EA4T to verify the rationality of the proposed *** simulation results indicate that the newly established crystal plasticity model can not only describe the cyclic softening characteristics of BCC axle steel EA4T well,but also reasonably describe the evolution laws of uniaxial ratcheting and nonproportional multiaxial ratcheting ***,the established crystal plastic cyclic constitutive model can reasonably predict the ratcheting behavior of BCC single crystal as well.

关键词： Crystal plasticity Constitutive model Softening Ratcheting

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