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Force Analysis of the Overconstrained Mechanisms Based on Equivalent Stiffness Considering Limb Axial Deformation

Chinese Journal of Mechanical Engineering 2023年第1期36卷 292-304页

作者： Jinwei Guo Yongsheng Zhao Bo Chen Guoxing Zhang Yundou Xu Jiantao Yao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao066004China

Overconstrained mechanism has the advantages of large bearing capacity and high motion reliability,but its force analysis is complex and difficult because the mechanism system contains *** the limb axial deformation,taking typical 2SS+P and 7-SS passive overconstrained mechanisms,2SPS+P and 7-SPS active overconstrained mechanisms,and 2SPS+P and 7-SPS passive-input overconstrained mechanisms as examples,a new force analysis method based on the idea of equivalent stiffness is *** equivalent stiffness matrix of passive overconstrained mechanism is derived by combining the force balance and deformation compatibility equations with consideration of axial elastic limb *** relationship between the constraint wrench magnitudes and the external force,limb stiffness is *** equivalent stiffness matrix of active overconstrained mechanism is derived by combining the force balance and displacement compatibility ***,the relationship between the magnitudes of the actuated wrenches and the external force,limb stiffness is *** with the equivalent stiffness of the passive overconstrained mechanism,an analytical relationship between the actuated forces of passive-input overconstrained mechanism and the output displacement,limb stiffness is ***,adaptability of the equivalent stiffness to overconstrained mechanisms is discussed,and the effect of the limb stiffness on overconstrained mechanisms force distribution is *** research results provide a theoretical reference for the design,research and practical application of overconstrained mechanism.

关键词： Active overconstrained Passive overconstrained Passive-input overconstrained Equivalent stiffness Force distribution

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Heat treatment and granule medium internal highpressure forming of AA6061 tube

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Journal of Central South University 2017年第5期24卷 1040-1049页

作者： BI Jiang ZHAO Chang-cai BI Meng-meng DU Bing CHEN Xiao-hua DONG Guo-jiang Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of Education of China Yanshan UniversityQinhuangdao 066004China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China College of Vehicles and Energy Yanshan UniversityQinhuangdao 066004China

The new forming process of AA6061 alloy tube, including solution treatment, granule medium internal high-pressure forming and aging treatment, was developed. The AA6061 alloy tube via heat treatment satisfied the forming requirement, and the granule medium internal high pressure forming method for AA6061 alloy tube was also realized by using convenient implementation with low requirement of equipment and flexible design of product. At a solution temperature of 560℃ and time of 120 min, the elongation of the AA6061 extruded tube increases by 300% and the strength and the hardness dramatically decrease too. Therefore, the AA6061 alloy tube meets the requirement of internal high-pressure forming because of the improvement of formability. The experiments shows that the strength and hardness of AA6061 alloy workpiece recover to that of the as-received alloy at an aging temperature of 180℃ and time of 360 min, and the strength of AA6061 alloy workpiece is equal to the base alloy. The typical parts of convex ring tube, stepped shaft tube and hexagonal tube were successfully produced in lab by using the present forming method. The forming tests show that the maximum expansion ratio(MER) of the AA6061 extruded tube increases by 25.5% and the material properties of formed AA6061 alloy tube reached the performance of as-received alloy.

关键词： aluminum alloy tube solution treatment aging treatment granule medium internal high pressure forming

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Hot tensile deformation behavior and constitutive model of ZK61M high-strength magnesium alloy sheet

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Rare Metals 2021年第5期40卷 1182-1190页

作者： Liu Yang Yong-Chuan Duan Ying-Ping Guan Zhen-Hua Wang Key Laboratory of Advanced Forging&Stamping Technolnology and Science Ministry of Education of ChinaYanshan UniversityQinhuangdao 066004China School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China

Hot deformation behavior of the annealed ZK61 M magnesium alloy sheet was explored using tensile tests with strain rates varying from 0.001 to 0.030 s^(-1) in temperatures range of 423-513 *** obtained results indicate that the flow stress increased with deformation temperature decreasing and strain rate *** recrystallization(DRX)occurs when the temperature is higher than 423 K,and the recrystallization volume fraction increases with temperature *** a given temperature,the measured DRX volume fraction at a higher strain rate is smaller than that at a lower strain *** are observed throughout the tested temperature ***,they grow larger as temperature *** average absolute relative error(AARE)of 2.65%proves that the peak stress predicted by the constitutive model is in good agreement with the experimental *** correlation coefficient(R’)obtained for the predicted stress and the experimental value considering the strain on the material constant are between 0.9831 and *** addition,AARE and root mean square error(RMSE)are less than 6.5%and 8.5 MPa,*** indicates that the deviation of the predicted value from the experimental value is small and the predictions of the proposed model are reliable.

关键词： ZK61M magnesium alloy sheet Hot tensile deformation Microstructure Constitutive model

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Kinematics and Dynamics Hessian Matrices of Manipulators Based on Screw Theory

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Chinese Journal of Mechanical Engineering 2015年第2期28卷 226-235页

作者： ZHAO Tieshi GENG Mingchao CHEN Yuhang LI Erwei YANG Jiantao Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University

The complexity of the kinematics and dynamics of a manipulator makes it necessary to simplify the modeling ***,the traditional representations cannot achieve this because of the absence of coordinate ***,the coordinate invariant method is an important research ***,the rigid-body acceleration,the time derivative of the twist,is proved to be a screw,and its physical meaning is *** on the twist and the rigid-body acceleration,the acceleration of the end-effector is expressed as a linear-bilinear form,and the kinematics Hessian matrix of the manipulator（represented by Lie bracket）is ***,Newton-Euler＇s equation is rewritten as a linear-bilinear form,from which the dynamics Hessian matrix of a rigid body is *** formulae and the dynamics Hessian matrix are proved to be coordinate *** to the principle of virtual work,the dynamics Hessian matrix of the parallel manipulator is gotten and the detailed dynamic model is *** index of dynamical coupling based on dynamics Hessian matrix is *** the end,a foldable parallel manipulator is taken as an example to validate the deduced kinematics and dynamics *** screw theory based method can simplify the kinematics and dynamics of a manipulator,also the corresponding dynamics Hessian matrix can be used to evaluate the dynamical coupling of a manipulator.

关键词： kinematics dynamics Hessian matrix parallel manipulator screw theory

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Characteristics of Precipitation in an As-cast Nb-and V-containing High Nitrogen CrMn Austenitic Steel

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Journal of Iron and Steel Research International 2014年第10期21卷 945-950页

作者： Zhong-ping SHI Zhen-hua WANG Shu-hua SUN Ze-an ZHOU Ying-ping GUAN Wan-tang FU State Key Laboratory of Metastable Materials Science and Technology Yanshan University Key Laboratory of Advanced Forging and Stamping Technology and Science(Yanshan University) Ministry of Education of China

The phase diagram of an Nb- and V-containing 18Mnl8Cr0.5N steel was investigated using thermodynam ic calculation. The compositions and characteristics of precipitates were investigated by scanning electron microsco- py, energy dispersive spectrometry, X-ray diffraction, and differential scanning calorimetry. Under equilibrium con- ditions, MX precipitates at 1 350 ℃. MX is a substitutional solid solution of Nb4 N3.38, and its composition （at. %） is approximately.. Nb 40, N 40, V 8, and Fe, Cr, and Mn balance. The precipitates, with shapes including irregular bulk, rod, and ellipsoid, are primarily distributed at grain boundaries and triple junctions, and their size is approxi- mately 5 10 μm. Finally, the microalloying of high nitrogen CrMn austenite steels, control of precipitate size, and the effect of precipitate on hot formin~ were discussed.

关键词： high nitrogen steel microalloying precipitate

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Shakedown Criterion Employing Actual Residual Stress Field and Its Application in Numerical Shakedown Analysis

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 919-927页

作者： ZOU Zongyuan GUO Baofeng LI Yinxiao JIN Miao ZHAO Shiyan Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Chinese 91315 People's Liberation Army Troops

Construction of the static admissible residual stress field and searching the optimal field are key tasks in the shakedown analysis methods applying the static theorem. These methods always meet dimension obstacles when dealing with complex problems. In this paper, a novel shakedown criterion is proposed employing actual residual stress field based on the static shakedown theorem. The actual residual stress field used here is produced under a specified load path, which is a sequence of proportional loading and unloading from zero to all the vertices of the given load domain. This ensures that the shakedown behavior in the whole load domain can be determined based on the theorem proposed by K6nig. The shakedown criterion is then implemented in numerical shakedown analysis, The actual residual stress fields are calculated by incremental finite element elastic-plastic analysis technique for finite deformation under the specified load path with different load levels. The shakedown behavior and the shakedown limit load are determined according to the proposed criterion. The validation of the criterion is performed by a benchmark shakedown example, which is a square plate with a central hole under biaxial loading. The results are consistent with existing results in the literatures and are validated by full cyclic elastic-plastic finite element analysis. The numerical shakedown analysis applying the proposed criterion avoids processing dimension obstacles and performing full cyclic elastic-plastic analysis under arbitrary load paths which should be accounted for appearing. The effect of material model and geometric changes on shakedown behavior can he considered conveniently.

关键词： elastoplastic finite element shakedown criterion specified load path actual residual stress field

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Deep drawing of cup shell by powder cavity flexible forming technology

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Journal of Central South University 2017年第4期24卷 766-772页

作者： XUE Ya-hong CHEN Ke FAN Cun-jie LUO Jun-ting Education Ministry Key Laboratory of Advanced Forging and Stamping Technology and Science Yanshan UniversityQinhuangdao 066004China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China

A forming method named powder cavity flexible forming was proposed. It is a forming technology which uses powder medium instead of rigid punch or die to form sheet metals. Cup shells were successfully obtained by this technology. The theoretical calculation equation of forming load was obtained through mechanical analysis and the stress state in cup shells was analyzed by finite element simulation. The results show that powder cavity flexible forming technology can improve the forming limit of sheet metal. Compared with rigid die forming process, the thickness reduction in the punch fillet area significantly decreases and the drawing ratio increases from 1.8 to 2.2. The thinning compressive stress in the bottom of cup shell emerges, which makes the bottom of the cup shell in three-dimensional stress state and the stress in punch fillet region decrease due to powder reaction force, which can effectively inhibit the sever thinning of the sheet and prevent the generation of fracture defects.

关键词： cup shell powder cavity flexible forming drawing finite element simulation

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Kinetostatics Analysis of a Novel 6-DOF Parallel Manipulator with Three Planar Limbs and Equipped with Three Fingers

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Chinese Journal of Mechanical Engineering 2014年第5期27卷 919-927页

作者： LU Yi LI Xuepeng College of Mechanical Engineering Yanshan University Key Laboratory of Parallel Robot and Mechatronic System of Hebei Province Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education

It is significant to develop a robot hand with high rigidity by a 6-DOF parallel manipulator（PM）.However,the existing6-DOF PMs include spherical joint which has less capability of pulling force bearing,less rotation range and lower precision under alternately heavy loads.A novel 6-DOF PM with three planar limbs and equipped with three fingers is proposed and its kinematics and statics are analyzed systematically.A 3-dimension simulation mechanism of the proposed manipulator is constructed and its structure characteristics is *** kinematics formulae for solving the displacement,velocity,acceleration of the platform,the active legs and the fingers are *** statics formulae are derived for solving the active forces of PM and the finger *** analytic example is given for solving the kinematics and statics of proposed manipulator and the analytic solved results are verified by the simulation *** is proved from the error analysis of analytic solutions and simulation solutions that the derived analytic formulae are correct and provide the theoretical and technical foundations for its manufacturing,control and application.

关键词： parallel manipulator planar limbs finger kinematics statics

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Analysis and Optimization of a Spatial Parallel Mechanism for a New 5-DOF Hybrid Serial-Parallel Manipulator

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Chinese Journal of Mechanical Engineering 2018年第3期31卷 60-68页

作者： Dong-Sheng Zhang Yun-Dou Xu Jian-Tao Yao Yong-Sheng Zhao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education Yanshan University

Hybrid manipulators have potentially application in machining industries and attract extensive attention from many researchers on the basis of high sti ness and high dexterity. Therefore,in order to expand the application prospects of hybrid manipulator,a novel 5?degree?of?freedom(DOF) hybrid serial?parallel manipulator(HSPM) is proposed. Firstly,the design plan of this manipulator is introduced. Secondly,the analysis of this manipulator is carried out in detail,including kinematics analysis,statics analysis,and workspace analysis. Especially,an amplitude equivalent method of disposing the over?constrained force/couple to the non?overconstrained force/couple is used in the statics analysis. Then,three performance indices are used to optimize the PM. Two of them have been widely used,and the third one is a new index which considers the characteristics of the actuated force. Based on the performance indices,the performance atlas is drawn and the optimal design of the PM is investigated. In order to satisfy the anticipant kinetic characteristics of the PM,the verification of the optimized physical dimension is done and the workspace based on the optimized physical dimension is carried out. This paper will lay good theoretical foundations for application of this novel HSPM and also can be applied to other hybrid manipulators.

关键词： Parallel mechanism Performance indices Optimal design Performance atlas

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Design and analysis of a truss deployable antenna mechanism based on a 3UU-3URU unit

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Chinese Journal of Aeronautics 2019年第12期32卷 2743-2754页

作者： Yundou XU Jinwei GUO Luyao GUO Wenlan LIU Jiantao YAO Yongsheng ZHAO Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao 066004China College of Energy and Power Engineering Lanzhou University of TechnologyLanzhou 730050China

Space deployable structures with large calibers, high accuracy, and large folding ratios are indispensable equipment in the aerospace field. Given that the single-DOF 3 RR-3 RRR deployable unit cannot be fully folded, this study proposes a 3 UU-3 URU deployable unit with two kinds of DOF: folding movement and orientation adjustment. First, based on the G-K formula, the DOF of the 3 UU-3 URU unit is analyzed. Then, the 3 UU-3 URU unit is used to construct a deployable truss antenna with a curved surface, and the DOF of the whole deployable antenna containing multiple 3 UU-3 URU units is calculated. The structural design of a deployable antenna with two loops is carried out with specific parameters and geometric relations. Next, a DOF simulation of a basic combination unit composed of three 3 UU-3 URU units is performed. Finally, a prototype of the basic combination unit is manufactured, and the DOF of the mechanism is experimentally verified.

关键词： Basic combination unit Degree of freedom(DOF) Deployable truss antenna Simulation analysis Structural design

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