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Heat treatment and granule medium internal highpressure forming of AA6061 tube

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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A novel architecture of electro-hydrostatic actuator with digital distribution

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Chinese Journal of Aeronautics 2021年第5期34卷 224-238页

作者： Jing YAO Pei WANG Zhaosheng DONG Dongting JIANG Tong SHA School of Mechanical Engineering Yanshan UniversityQinhuangdcio 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of Education of China Ycmshan UniversityQinhuangdao 066004China Hebei Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Ycmshan UniversityQinhuangdao 066004China

To address the flow imbalance rapidly of the asymmetric Electro-Hydrostatic Actuator(EHA),this paper presents a novel architecture of asymmetric EHA with the Digital Distribution(EHA-DD).It also improves the flow nonlinearity and control accuracy of the pump,especially in the low-speed *** digital distribution with two High-Speed on–off Valves(HSVs)not only balances flow instead of the check valves,but also replaces the pump at the low-speed to control output flow by adjusting the PWM *** pump and HSVs are the crucial components to control flow ***,the flow calculation models of the pump and the duty ratio inversed model of the HSV are obtained through experimental tests and the identification *** get the control input signal for the required flow,the pump speed and PWM duty ratio for the HSVs are inversed to compensate for flow ***,a multimode digital flow distribution control method based on pump speed,mainly including the pump-controlled mode for large flow demand and valve-controlled mode for little flow demand,is proposed to control the accurate flow output *** step extension experiments based on the flow calculation models are conducted on the EHA-DD prototype under elastic,opposite varying *** results demonstrate that the EHADD realizes little position error by accurate flow control,and it is also beneficial to improve the service life of the pump.

关键词： Asymmetrical flow Digital distribution EHA High-speed on–off valve Nonlinearity PWM control

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Theoretical Model of Dynamic Bulk Modulus for Aerated Hydraulic Fluid

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 183-193页

作者： Xiaoming Yuan Weiqi Wang Xuan Zhu Lijie Zhang Hebei Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan UniversityQinhuangdao 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science Ministry of Education of ChinaYanshan UniversityQinhuangdao 066000China State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China

Existing models of bulk modulus for aerated hydraulic fluids primarily focus on the effects of pressure and air fraction,whereas the effect of temperature on bulk modulus is *** on the lumped parameter method and the full cavitation model,combined with the improved Henry’s law and the air polytropic course equation,a theoretical model of dynamic bulk modulus for an aerated hydraulic fluid is *** effects of system pressure,air fraction,and temperature on bulk modulus are investigated using the controlled variable *** results show that the dynamic bulk modulus of the aerated hydraulic fluid is inconsistent during the compression *** the same pressure point,the dynamic bulk modulus during expansion is higher than that during *** the same initial air faction and pressure changing period,a higher temperature results in a lower dynamic bulk *** the pressure is lower,the dynamic bulk modulus of each temperature point is more similar to each *** comparing the theoretical results with the actual dynamic bulk modulus of the Shell Tellus S ISO32 standard air-containing oil,the goodness-of-fit between the theoretical model and experimental value at three temperatures is 0.9726,0.9732,and 0.9675,which validates the theoretical *** this study,a calculation model of dynamic bulk modulus that considers temperature factors is *** predicts the dynamic bulk modulus of aerated hydraulic fluids at different temperatures and provides a theoretical basis for improving the analytical model of bulk modulus.

关键词： Aerated hydraulic fluid Dynamic bulk modulus Theory model Air fraction Pressure

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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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Effect of axial preloading on mechanical behavior during the free-end torsion of an extruded AZ31 magnesium alloy

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International Journal of Minerals,Metallurgy and Materials 2022年第7期29卷 1351-1360页

作者： Qun Li Dan Meng Zhichang Fu Hui Zhao Chong Yang Yan Peng Baodong Shi Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of Education School of Mechanical EngineeringYanshan UniversityQinhuangdao 066004China National Engineering Research Center for Equipment and Technology of Cold Rolled Strip School of Mechanical EngineeringYanshan UniversityQinhuangdao 066004China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China

Large plastic deformation commonly occurs during the practical forming process in *** with uniaxial tension/compression,torsion is a more effective approach to investigate mechanical behavior under large *** response of the large strain torsion of magnesium alloy is sensitive to the initial texture and ***,an extruded AZ31 alloy was pre-stressed in tension and compression to introduce dislocations and twins in the current ***,torsion tests were conducted to clarify the effects of twinning and dislocation on subsequent deformation *** corresponding microstructure and deformation mechanisms were explored on the basis of viscoplastic self-consistent(VPSC)*** experimental observations on stress-strain responses and pole figures were captured by simulation *** was found that twins make less contribution to plastic deformation,which results in small change in texture direction under pure torsion and torsion after *** activity of the slip/twin system and the mechanical properties are affected by different initial textures and active conditions of the ***,the stress state during combined tension-torsion loading benefits the reduction of texture intensity.

关键词： magnesium alloy torsion twinning dislocation texture viscoplastic self-consistent

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Frictional characteristics of granular system under high pressure

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Journal of Central South University 2016年第5期23卷 1132-1141页

作者：曹秒艳彭雅新赵长财董国疆杜冰 national engineering research center for equipment and technology of cold strip rolling(yanshan university) Qinhuangdao 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of Education of China(Yanshan University) Qinhuangdao 066004China College of Vehicles and Energy Yanshan UniversityQinhuangdao 066004China

In order to reveal the force transmission features of the granules in the solid granule medium forming(SGMF) technology,the frictional characteristics of the non-metallic granule medium(NGM) under high pressure were investigated by tests and *** the relevant changing curves of the internal friction coefficient of the granular system under different normal pressures were obtained by self-designed shear *** the granule volume compression test,the accurate discrete element simulation parameters were obtained,based on this,the discrete element method(DEM) was adopted to reveal the evolution law of the NGM granules movement in the sample shear process from the microscopic *** on the DEM,the influence of granule diameter,surface friction coefficient,normal pressure and shear velocity on the internal friction coefficient of the granular system were *** the parameters were conducted to be dimensionless by introducing the inertia ***,the expression showing power-law relationship of inertia coefficient,surface friction coefficient and internal friction coefficient is obtained.

关键词： granule friction coefficient discrete element method inertia coefficient

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Innovative design and optimization of a two-dimensional deployable nine-grid planar antenna mechanism with a flat reflection surface

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Chinese Journal of Aeronautics 2023年第11期36卷 529-550页

作者： Bo CHEN Ze JIANG Xinlu WEI Luyao GUO Xin ZHOU Yundou XU Junjie QIAN 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 Space Structure and Mechanism Technology Laboratory of China Aerospace Science and Technology Group Co.Ltd Shanghai 201109China Aerospace System Engineering Shanghai Shanghai 201109China

With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical *** this paper,a planar deployable mechanism is proposed,which can form a flat reflection surface with a small gap between *** this end,a novel large-scale two-dimensional deployable nine-grid planar antenna mechanism is ***,two antenna folding schemes and four supporting mechanism schemes are *** comparison analysis,the antenna configuration scheme with the best comprehensive performance is selected.A kinematic model of the deployable mechanism is established,and its kinematic characteristics are ***,the correctness of the kinematic model is verified by comparing the analytical and simulation results of the kinematic ***,a finite element model of the antenna is *** on the response surface method,the structural parameters of the support rods of the antenna are optimized,and a set of optimized solutions with lightweight and high fundamental frequency characteristics are ***,a prototype of the proposed nine-grid planar antenna is *** feasibility of the deployment principle and the rationality of the designed mechanism are verified by deployment experiments.

关键词： Design optimization Kinematics Planar antenna Structural design Two-dimensional expansion

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Kinematic,Workspace and Force Analysis of A Five-DOF Hybrid Manipulator R(2RPR)R/SP+RR

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 232-243页

作者： Yundou Xu Fan Yang Youen Mei Dongsheng Zhang Yulin Zhou Yongsheng Zhao Laboratory of Parallel Robot and Mechatronic System of Hebei Province Yanshan UniversityQinhuangdao 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao 006004China School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China Tencent Robotics X Tencent HoldingsShenzhen 518057China

In the present study,the over-constrained hybrid manipulator R(2RPR)R/SP+RR is considered as the research *** this paper,kinematics of the hybrid manipulator,including the forward and inverse position,are ***,the workspace is checked based on the inverse position solution to evaluate whether the workspace of the hybrid manipulator meets the requirements,and the actual workspace of the hybrid robot is *** that,the force analysis of the over-constrained parallel mechanism is carried out,and an ADAMS-ANSYS rigid-flexible hybrid body model is established to verify the *** on the obtained results from the force analysis,the manipulator structure is ***,the structure optimization is carried out to improve the robot ***,calibration and workspace verification experiments are performed on the prototype,cutting experiment of an S-shaped aluminum alloy workpiece is completed,and the experiment verifies the machining ability of the *** work conducts kinematics,workspace,force analyses,structural optimization design and experiments on the over-constrained hybrid manipulator R(2RPR)R/SP+RR,providing design basis and technical support for the development of the novel hybrid manipulator in practical engineering.

关键词： Hybrid manipulator Over-constrained Kinematic analysis Stiffness analysis

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Hydraulic bulging process with axial feedings and strain field of U-shaped metal bellows

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Journal of Central South University 2018年第11期25卷 2712-2721页

作者： HAO Zeng-liang XI Chen-yang HUANG Zhi-heng ZHANG Chun-xiang LUO Jun-ting Education Ministry Key Laboratory of Advanced Forging&Stamping Technology and Science Yanshan UniversityQinhuangdao 066004China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China

Based on the traditional hydraulic bulging process,an improved hydraulic bulging process with axial feeding in the bulging process was *** finite element simulation and experiment of bellows formed by the traditional and improved hydraulic bulging processes were *** grid strain measurement system analysis results of strain and wall thickness distribution of the metal bellows,obtained from simulation and experiment,show that the maximum thinning rates of the wall thickness under the traditional and improved processes were 15%and 10%,*** the wall thickness distribution of the metal bellows formed with improved process was more *** strain values from the root to crown of the waveform increased ***,the strain values were smaller than those of traditional process due to the axial feeding of the improved process in bulging process.

关键词： hydraulic bulging process finite element simulation thinning rate of wall thickness grid strain measurement system

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A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

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Chinese Journal of Mechanical Engineering 2020年第6期33卷 134-157页

作者： Yongquan Li Yang Zhang Lijie Zhang Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao066004China Key Laboratory of Advanced Forging&Stamping Technology and Science Ministry of Education of ChinaYanshan UniversityQinhuangdao066004China School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen518052China Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan UniversityQinhuangdao066004China

The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms,or using screw theory to perform multiple getting intersection and union to complete type *** number of redundant parallel mechanisms obtained by these two methods is *** this paper,based on Grassmann line geometry and Atlas method,a novel and effective method for type synthesis of redundant actuated parallel mechanisms(PMs)with closed-loop units is ***,the degree of freedom(DOF)and constraint line graph of the moving platform are determined successively,and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph,and a branch constraint allocation scheme is formulated based on the allocation ***,a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop ***,the branch chains that meet the requirements of branch chains configuration criteria and F&C(degree of freedom&constraint)line graph are *** this paper,two types of 2 rotational and 1 translational(2R1T)redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational(2T1R)redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples,and 238,92 and 15 new configurations were *** the mechanisms contain closed-loop units,and the mechanisms and the actuators both have good ***,all the mechanisms have excellent comprehensive performance,in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently *** instantaneous analysis shows that all mechanisms are not instantaneous,which proves the feasibility and practicability of the method.

关键词： Redundant actuated Parallel mechanisms Type synthesis Atlas method Instantaneous analysis

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