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Kinematic characteristics analysis and assembly application of a spatial symmetric 7R mechanism

Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica 2019年第4期40卷 422536页

作者： Han, Bo Xu, Yundou Yao, Jiantao Zheng, Dong Zhang, Shuo Zhao, Yongsheng Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao066004 China Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Qinhuangdao066004 China

A spatial symmetric 7R mechanism is proposed in this paper, constructing space deployable mechanisms. Firstly, the overall degree of freedom (DOF) is analyzed based on the screw constraint topology diagram, obtaining the variation of DOFs of the whole mechanism when the orientation of the joint axes changes. Then, the number and nature of DOFs of the motion output component in different orientations of the joint axes are analyzed based on the inverse screw theory. and the transient nature of the DOFs are analyzed. It is found that passive DOF and instantaneous DOF occurred in the arrangement of different joint axes orientations. Furthermore, the singular characteristics of the mechanism in different driving conditions are analyzed, obtaining the geometric conditions of the mechanism in the singular configuration under different driving conditions. Finally, a class of single-DOF polygonal pyramid-shaped space deployable mechanism is constructed by combining spatial symmetric 7R mechanisms with DOF at one. By setting the joint axes orientations, the mechanism yields a large folding rate, and due to its singular properties, it has good mechanical properties. Through the combination of a plurality of pyramid-shaped space deployable mechanisms, new large-scale space deployable mechanisms can be constructed, showing good application prospects in the aerospace field. © 2019, Press of Chinese Journal of Aeronautics. All right reserved.

关键词： Mechanisms

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General Analytical Shakedown Analysis of a Structure Subjected to Combined Loading with Constant and Cyclic Loads

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Journal of Harbin Institute of technology(New Series) 2017年第3期24卷 67-75页

作者： Zongyuan Zou Baofeng Guo Miao Jin Key Laboratory of Advanced Forging & Stamping Technology and Science Ministry of Education of China Yanshan UniversityQinhuangdao 066004 China

The shakedown behavior of structures subjected to a combined loading of constant and cyclic loads has been well *** some specified problems,shakedown limit loads have been ***,the general effect of combined loading on the structural shakedown has not yet been *** general analytic solution of the elastic shakedown limit load is thus derived for a structure subjected to combined ***'s extended static shakedown theorem for combined loading is *** stress field in equilibrium with the external constant load required in Polizzotto's extended theorem is constructed by subtracting the reference elastic stress field of the peak cyclic load from the elastic-plastic stress field of the combined constant load and peak cyclic *** shakedown condition of the stress field is then derived according to the extended *** the analytical analysis of the shakedown condition,the structural shakedown behavior under combined loading is investigated.A general solution of the shakedown limit load is then derived,and the effects of the combined loading on the shakedown behavior are *** obtained general analytical result is applied to a hollow tension specimen under constant tension and alternating torsion and a plate with a central hole under constant and cyclic *** results are consistent with the solutions reported in the literature.

关键词： elastic-plastic shakedown limit load general analytical solution combined loading

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Effect of Rolling Reduction Rate on the Microstructure of Hot Rolling Stainless Steel Clad Plate 5

Effect of Rolling Reduction Rate on the Microstructure of Ho...

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2018 5th International Conference on advanced Composite Materials and Manufacturing Engineering, ACMME 2018

作者： Jin, Herong Zhang, Lei Yi, Yali Key Lab. of Advanced Forging and Stamping Technology and Science of Ministry of National Education Yanshan University Qinhuangdao066004 China Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao066004 China School of Mechanical Engineering Yanshan University Qinhuangdao066004 China

The macro-scale and meso-scale simulation models of stainless steel clad plate were established by DEFORM-3D. The multi-scale coupling simulations of clad plate with different rolling parameters were carried out. The seven pass hot rolling process of stainless steel clad plate was simulated by numerical simulation. By contrasting the vertical stress and the deformation resistance of cladding layer, the rolling reduction rate satisfying interface bonding was obtained. The grain distribution at the center of the substrate layer was analyzed and reasonable hot rolling reduction rates were selected considering their effects on the recrystallization volume percent and the grain size. The results show that the grain size decreases with the increase of reduction rate. However, too much reduction rate will decrease the rate of recrystallization volume percent and the refining effect of grain is not obvious. To ensure uniform grain size distribution, it is most reasonable to set the rolling temperature to 1150°C and the reduction rate to 50%. © Published under licence by IOP Publishing Ltd.

关键词： Stainless steel

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Kinematic and Dynamic Modeling of Parallel-serial Hybrid Stabilizing Crane Mechanism

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Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery 2018年第8期49卷 411-419and49页

作者： Li, Erwei Zhao, Tieshi Hu, Qiangqiang Wang, Chang Geng, Mingchao Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System Laboratory Yanshan University Qinhuangdao066004 China Key Laboratory of Advanced Forging and Stamping Technology and Science Ministry of Education Yanshan University Qinhuangdao066004 China College of Mechanical Engineering Hebei University of Architecture Zhangjiakou075000 China

Stabilizing crane plays an important role in the lifting of cargo between ships and offshore platforms, such as wind turbine and drilling platform under high sea conditions. According to the characteristics of motion compensation offshore, a parallel-serial hybrid stabilizing crane mechanism was proposed. The parallel part is a two degrees of freedom (DOF) rotational parallel mechanism (RPM), which has two continuously rotational DOF. The parallel part, with a virtual continuous axis, can isolate the impact of the rolling and pitching of the moored ship to provide a stable base for the serial part: PRRP kinematic chain. The serial part has the degree of heave, yaw, tilt and telescope. The whole stabilizing crane can keep the end point of the crane staying still relative to the earth. Firstly, the hybrid mechanism was described and the corresponding coordinate systems were established. Then, assuming the parallel part and the first P kinematic pair of the serial part compensated the motion of the moored ship, in the non-inertial system, combined the vector method and screw velocity and acceleration theories, the kinematic model of end of the stable gangway stabilizing at a fixed point was established in accordance with the sequence of the parallel part and the serial part. Based on Newton-Euler formulas in screw form and combined D'Alembert principle and virtual work principle, the dynamic model of the hybrid mechanism was established in accordance with the sequence of the serial part and the parallel part. Finally, the correctness of the models was verified by a numerical example. The work laid a theoretical foundation for the engineering application of the stabilizing crane. © 2018, Chinese Society of Agricultural Machinery. All right reserved.

关键词： Kinematics

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抛物线型零件固体颗粒介质成形变形理论研究(英文)

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Journal of Zhejiang University-science A(Applied Physics & Engineering) 2017年第3期18卷 194-211页

作者： Xiang-dong JIA Chang-cai ZHAO Jian-chao LI Liu-yang HE MOE Key Laboratory of Advanced Forging & Stamping Technology and Science Yanshan University Qinhuangdao 066004 China

目的:板材固体颗粒介质成形工艺作为一种新型的软模成形技术,是采用固体颗粒代替刚性凸模或凹模(或弹性体、液体)对板料进行成形加工的工艺。固体颗粒介质板材拉深成形工艺为拉深和胀形两种变形模式的复合成形,其变形过程与传统拉深成... 详细信息

目的:板材固体颗粒介质成形工艺作为一种新型的软模成形技术,是采用固体颗粒代替刚性凸模或凹模(或弹性体、液体)对板料进行成形加工的工艺。固体颗粒介质板材拉深成形工艺为拉深和胀形两种变形模式的复合成形,其变形过程与传统拉深成形工艺有很大的区别。以抛物线型零件为研究对象,对其成形过程进行研究,建立固体颗粒介质板材软凸模拉深成形的几何条件和应变计算公式。创新点:1.首次提出了描述固体颗粒介质板材拉深成形变形机理的拉深权和胀形权的概念,并建立了相应的计算公式;2.建立了固体颗粒介质抛物线型零件软凸模拉深成形的几何条件和应变计算公式。方法:1.通过对抛物线型零件固体颗粒介质拉深成形的变形过程分析(图1~3),将变形过程和成形工件的变形区进行划分;2.将数学中权函数的思想引入到对抛物线型零件固体颗粒介质拉深成形的分析中,提出拉深权和胀形权的定义及相应表达式(公式(1)和(2));3.通过理论推导,构建不同成形阶段抛物线型零件拉深成形过程中的应变计算式(公式(28)^(30)和公式(62a)^(62c))和壁厚计算公式(公式(31)和(63));4.利用MATLAB编制抛物线型零件拉深成形应变计算程序(图14);5.以某航空零件为目标零件,通过试验试制不同成形条件下不同阶段的抛物线型工件(表2和3),将理论计算壁厚与实测厚度进行对比(图19),将试验轮廓与理论计算轮廓进行对比(图21),验证分析过程中所提假设及理论计算的可行性和正确性;将试验获得成形工件的几何尺寸(表3)代入MATLAB计算程序中,对该航空零件的变形过程进行分析(图15、18、19、21和22)。结论:1.固体颗粒介质拉深成形过程是胀形和拉深的复合成形,通过对其变形过程分析,首次提出了拉深权和胀形权的概念,并且给出了其计算公式。成形过程中,拉深权越大,工件成形后的壁厚差越小;胀形权则正好相反。2.利用拉深权和胀形权,建立了固体颗粒介质软凸模拉深成形变形区应变计算公式,且可以计算出应变分界圆位置半径,为分析固体颗粒介质软凸模拉深成形工艺变形过程提供了新的理论依据。3.设置合理的成形条件、拉深权的提高和应变分界圆半径的缩小可以降低拉深成形过程中底部的过度减薄,进而提高极限成形高度。

关键词：固体颗粒介质软模成形拉深拉深权胀形权应变

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Mechanical properties in cyclic tension-compression loading process on sheet metal

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Procedia Manufacturing 2018年 15卷 1769-1776页

作者： Gaochao Yu Rui Ma Ruixue Zhai Jun Zhao Key Laboratory of Advanced Forging & Stamping Technology and Science (YanShan University) Ministry of Education of China Qinhuangdao 066004 P.R. China College of Mechanical Engineering Yanshan University Qinhuangdao 066004 P.R. China

In the process of reciprocating bending, any particle of the workpiece is subjected to cyclic tensile compression deformation. The workpiece undergoes a reciprocating bending deformation process, and each particle undergoes a cyclic tension-compression loading cycle. In this paper, cyclic tensile loading tests under different prestrains and strain amplitudes are carried out. The macroscopic behavior of 304 stainless steel and ST12 cold rolled plate under cyclic tension-compression loading and the effect of prestrain on the stable hysteresis loop of the two materials are studied. Thus, the evolution of macroscopic mechanical properties in the process of reciprocating bending deformation is deeply understood. The experimental results show that 304 stainless steel and ST12 cold rolled plate are characterized by cyclic softening; the prestrain has little effect on the stable hysteresis loop, the cyclic tension-compression loading eliminates the initial difference of the mechanical properties caused by the prestrain and makes the mechanical properties of materials tend to be uniform. It is also proved indirectly that the reciprocating bending has not only the effect of uniform curvature, but also makes the mechanical properties of the same layer of fibers be homogenized.

关键词： Cyclic tension-compression Prestrain Hysteresis loop Mechanical property Cyclic softening

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Frictional characteristics of sheet metals with superimposed ultrasonic vibrations

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Journal of Central South University 2018年第8期25卷 1879-1887页

作者： CAO Miao-yan LI Jian-chao LIU Yan-yang YUAN Ya-ning ZHAO Chang-cai DONG Guo-jiang National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao 066004China Chinese Academy of Agricultural Mechanization Sciences Beijing 100083China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of Education of China Yanshan UniversityQinhuangdao 066004China College of Vehicles and Energy Yanshan UniversityQinhuangdao 066004China

The forming performance of sheet metals in the deep-drawing process with ultrasonic vibrations can be improved by the surface effect between the sheet metal and the die.A sheet metal friction test with ultrasonic vibrations is performed to explore the cause of the surface *** frictional characteristics are investigated,and the corresponding friction expressions are established based on the contact mechanics and the elastic–plastic contact model for rough *** is caused by the elastic–plastic deformation of contacting asperities under normal *** actual contacting region between two surfaces increases with normal loads,whereas the normal distance *** normal distance between the contacting surfaces is changed,asperities generate a tangential deformation with ultrasonic vibrations,and the friction coefficient is eventually *** vibrations are applied on a 40Cr steel punch at the frequency of 20 kHz and the amplitude of 4.2μ*** the friction tests,the punch is perpendicular to the surface of the magnesium alloy AZ31B sheet metals and is sliding with a relative velocity of 1 mm/*** test results show that the friction coefficient is decreased by approximately 40%and the theoretical values are in accordance with the test values;Ultrasonic vibrations can clearly reduce wear and improve the surface quality of parts.

关键词： friction ultrasonic vibrations sheet metals contact model

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Tailored properties of a novelly-designed press-hardened 22MnMoB steel

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Journal of Iron and Steel Research International 2017年第5期24卷 508-512页

作者： Ming-bo Zhou Jing-lin Tang Jie Yang Cun-yu Wang Key Laboratory of Advanced Forging & Stamping Technology and Science (Yanshan University) Ministry of Education of China Qinhuangdao 066004 Hebei China Lightweight Research Department Society of Automotive Engineers of China Beijing 100055 China Central Iron & Steel Research Institute Beijing 100081 China

A novel 22MnMoB hot stamping steel was designed. The continuous cooling transformation （CCT） measurement of the 22MnMoB steel showed that the ferrite-bainite microstructure could be obtained at cooling rates lower than 25 ℃/s, and the complete martensite structure required the cooling rate higher than 30 ℃/s. The experiments with non-uniform die temperatures were carried out to obtain tailored properties. The results showed that strength of 1 411 MPa and elon- gation of 6% could be obtained in the hard zone, and strength of 916 MPa and elongation of 9% could be obtained in the soft zone, which can be realized by controlling the die temperature at 400 ℃. The transition zone was found smooth and could be beneficial to reduce the stress concen tration and therefore improve the performance of components.

关键词： Hot stamping Bainite Tailored property Mechanical property Microstructure

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Co-simulation technology of casting-forging combination forming process for grain distribution prediction

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Cailiao Daobao/Materials Review 2017年第1期31卷 150-154页

作者： Wang, Wei Ma, Rui Zhao, Jun Zhai, Ruixue Key Laboratory of Advanced Forging & Stamping Technology and Science Yanshan University Qinhuangdao066004 China

A co-simulation technology of casting-forging combination forming process was developed. Initial nonuniform cas-ting grain size was obtained from CAFE module of ProCAST software by casting simulation. A Fortran program was compiled as a function module of Deform-3D software to establish the coupling between the initial nonuniform casting grain size distribution and the Deform-3D forging model. The simulation of microstructure evolution during the forging process was realized though the secondary development of Deform-3D software. Finally, the distribution of dynamic recrystallized grain size and dynamic recrystallization vo-lume fraction could be predicted. The casting-forging combination forming of the cutting pick body was simulated by the developed co-simulation technology. The distribution of dynamic recrystallized grain size and dynamic recrystallization volume fraction of the two models, one model with initial uniform grain size, another with initial nonuniform grain size form the casting simulation, were acquired respectively. The feasibility of co-simulation technology of casting-forging combination forming process for grain distribution prediction was proved by the comparison result analysis. © 2017, Materials Review Magazine. All right reserved.

关键词： Forecasting

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General Analytical Shakedown Solution for Structures with Kinematic Hardening Materials

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Chinese Journal of Mechanical Engineering 2016年第5期29卷 944-953页

作者： GUO Baofeng ZOU Zongyuan JIN Miao Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University

The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems： a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

关键词： elastic-plastic elastic shakedown kinematic hardening shakedown limit load general analytical solution

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