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A novel architecture of electro-hydrostatic actuator with digital distribution

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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Type Synthesis of Two-Degrees-of-Freedom Rotational Parallel Mechanism with Two Continuous Rotational Axes

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Chinese Journal of Mechanical Engineering 2016年第4期29卷 694-702页

作者： XU Yundou ZHANG Dongsheng WANG Min YAO Jiantao ZHAO Yongsheng Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Key Laboratory of Advanced Forging and Stamping Technology and Science of Ministry of National Education Yanshan University Library Yanshan University

The two-rotational-degrees-of-freedom（2R） parallel mechanism（PM） with two continuous rotational axes（CRAs） has a simple kinematic *** is therefore easy to implement trajectory planning,parameter calibration,and motion control,which allows for a variety of application ***,no systematic analysis on structural constraints of the 2R-PM with two CRAs has been performed,and there are only a few types of 2R-PM with two ***,a theory regarding the type synthesis of the 2R-PM with two CRAs is systematically ***,combining the theories of reciprocal screw and space geometry,the spatial arrangement relationships of the constraint forces applied to the moving platform by the branches are explored,which give the 2R-PM two *** different distributions of the constraint forces in each branch are also *** the basis of the obtained structural constraints of branches,and considering the geometric relationships of constraint forces in each branch,the appropriate kinematic chains are *** the reasonable configuration of branch kinematic chains corresponding to every structural constraint,a series of new 2R-PMs with two CRAs are finally obtained.

关键词： type synthesis continuous rotational axes two rotational degrees of freedom parallel mechanism constraint force

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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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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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Application of Parallel Mechanism in Varistructured Quadruped/Biped Human-carrying Walking Chair Robot

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International Journal of Automation and computing 2013年第5期10卷 447-454页

作者： Ling-Feng Sang Hong-Bo Wang Dian-Fan Zhang Zhen-Hua Tian Fu-Hai Deng De-Lei Fang Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Science and Technology Research Institute Yanshan University

For the existing problems of walking chair robot such as simple function,lower bearing capacity and not walking in complex environment,a novel varistructured quadruped / biped human-carrying walking chair robot is *** proposed robot could be used as biped and quadruped walking chair *** the conversion of the walking chair robot from the quadruped to the biped or vice versa,6-UPS and 2-UPS＋UP（U,P and S are universal joint,the prismatic pair,and sphere joint,respectively） parallel mechanisms are selected as the leg mechanism of the biped walking robot and quadruped walking robot,*** the screw theory and theory of mechanism,the degrees of freedom of the leg mechanism and the body mechanism in diferent motion states are computed so as to meet the requirements of mechanism *** motion characteristics of the 2-UPS＋UP parallel mechanism which is the key part of the walking chair robot are ***,the workspace of the moving platform is drawn and the efect of the structural parameters on the workspace volume is ***,it is found that the volume of the workspace of the moving platform is bigger when the side length ratio and the vertex angle ratio of the fxed platform and the moving platform which are isosceles triangles are close to *** study provides a theoretical foundation for the prototype development.

关键词： Human-carrying walking chair robot parallel leg mechanism degree of freedom varistructure workspace kinematics

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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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Finite element simulation and experimental test of the wear behavior for self-lubricating spherical plain bearings

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Friction 2018年第3期6卷 297-306页

作者： Yahong XUE Jigang CHEN Sumin GUO Qingliang MENG Junting LUO School of Mechanical Engineering Yanshan University Aviation Key Laboratory of Science and Technology on Generic Technology of Self-Lubricating Spherical Plain Bearing Yanshan University Education Ministry Key Laboratory of Advanced Forging and Stamping Technology and Science Yanshan University

In this study, based on the classical Archard adhesion wear theory, a three-dimensional finite element model was established, with the aim of simulating the failure process of self-lubricating spherical plain bearings in the swinging wear condition. The results show that the self-lubricating spherical plain bearings go through two different stages during the wear process, namely, initial wear stage and stable wear stage. Because the large contact points wear out during the initial wear stage, the maximum contact pressure decreases as the test period increases. The relatively larger wear depth region shows elliptical distribution, and the maximum distribution appears in the central contact area. The wear depth reaches 0.974 mm after swinging 25,000 times. PTFE fibers, which possess a good friction performance but poor abrasion resistance, abundantly exist on the friction surfaces of the fabric liner. Consequently, the friction torque during the initial wear stage is slightly smaller than the friction torque during the stable wear stage; however, the wear rate during the initial wear stage is high. The reliability and effectiveness of the finite element model are verified by experiment. The developed finite element model can be used for the analysis of the wear mechanisms of bearings and the prediction of the service life of bearings.

关键词： spherical plain bearing wear mechanisms wear depth contact pressure simulation

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Operation and Force Analysis of the Guide Wire in a Minimally Invasive Vascular Interventional Surgery Robot System

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Chinese Journal of Mechanical Engineering 2015年第2期28卷 249-257页

作者： YANG Xue WANG Hongbo SUN Li YU Hongnian Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University School of Mechanical Engineering University of Jinan Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Faculty of Science and Technology Bournemouth University

To develop a robot system for minimally invasive surgery is significant,however the existing minimally invasive surgery robots are not applicable in practical operations,due to their limited functioning and weaker perception.A novel wire feeder is proposed for minimally invasive vascular interventional *** is used for assisting surgeons in delivering a guide wire,balloon and stenting into a specific lesion *** contrasting those existing wire feeders,the motion methods for delivering and rotating the guide wire in blood vessel are described,and their mechanical realization is presented.A new resistant force detecting method is given in *** change of the resistance force can help the operator feel the block or embolism existing in front of the guide *** driving torque for rotating the guide wire is developed at different *** the CT reconstruction image and extracted vessel paths,the path equation of the blood vessel is *** the shapes of the guide wire outside the blood vessel,the whole bending equation of the guide wire is *** is a risk criterion in the delivering *** process can make operations safer and man-machine interaction more reliable.A novel surgery robot for feeding guide wire is designed,and a risk criterion for the system is given.

关键词： minimally invasive wire feeder force analysis moment of inertia risk criterion

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An Iterative Compensation Algorithm for Springback Control in Plane Deformation and Its Application

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Chinese Journal of Mechanical Engineering 2019年第2期32卷 212-223页

作者： Rui Ma Chunge Wang Ruixue Zhai Jun Zhao Key Laboratory of Advanced Forging & Stamping Technology and ScienceMinistry of Education of China Yanshan University College of Mechanical Engineering Yanshan University College of Mechanical and Energy Engineering Ningbo Institute of Technology Zhejiang University Key Laboratory of Roll Forming Technology Research

In order to solve the springback problem in sheet metal forming, the trial and error method is a widely used method in the factory, which is time-consuming and costly for its non-direction and non-quantitative. Finite element simulation is an e ective method to predict the springback of complex shape parts, but its precision is sensitive to the simulation model, particularly material model and boundary conditions. In this paper, the simple iterative method is introduced to establish the iterative compensation algorithm, and the convergence criterion of iterative parameters is put forward. In addition, the new algorithm is applied to the V-free bending and stretch-bending processes, and the convergence of curvature and bending angle is proved theoretically and verified experimentally. At the same time,the iterative compensation experiments for plane bending show that, the new method can predict the next compensaantido tnh ev atlaureg ebta cseurdv oatnu trhe ew sitphri tnhgeb earcrko ro fo fe laecshs ttehsat,n s0 o. 5 th%a ta rteh eo btatraigneet db aefntedri n2 g-3 a nitgelrea tiwoitnhs.t Thhei se rrreosre aorf clhe sps rtohpaons e±s 0 a.1%new iterative compensation algorithm to predict springback in sheet metal forming process, where each compensation value depends only on the iteration parameter di erence before and after springback for the same forming process of same material.

关键词： Springback control Iterative compensation algorithm Convergence criterion V-free bending Stretchbending

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Global Dynamic Modeling of Electro-Hydraulic 3-UPS/S Parallel Stabilized Platform by Bond Graph

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Chinese Journal of Mechanical Engineering 2016年第6期29卷 1176-1185页

作者： ZHANG Lijie GUO Fei LI Yongquan LU Wenjuan Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University

Dynamic modeling of a parallel manipulator（PM） is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the global dynamic model of the PM system becomes increasingly prominent. Currently there lacks further research in global dynamic modeling. A unified modeling approach for the multi-energy domains PM system is proposed based on bond graph and a global dynamic model of the 3-UPS/S parallel stabilized platform involving mechanical and electrical-hydraulic elements is built. Firstly, the screw bond graph theory is improved based on the screw theory, the modular joint model is modeled and the normalized dynamic model of the mechanism is established. Secondly, combined with the electro-hydraulic servo system model built by traditional bond graph, the global dynamic model of the system is obtained, and then the motion, force and power of any element can be obtained directly. Lastly, the experiments and simulations of the driving forces, pressure and flow are performed, and the results show that, the theoretical calculation results of the driving forces are in accord with the experimental ones, and the pressure and flow of the first limb and the third limb are symmetry with each other. The results are reasonable and verify the correctness and effectiveness of the model and the method. The proposed dynamic modeling method provides a reference for modeling of other multi-energy domains system which contains complex PM.

关键词： screw bond graph multi-energy domains 3-UPS/S parallel mechanism electro-hydraulic servo system

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