检索结果-内蒙古大学图书馆

Hot Granules Medium Pressure Forming Process of AA7075 Conical Parts

Chinese Journal of Mechanical Engineering 2015年第3期28卷 580-591页

作者： DONG Guojiang ZHAO Changcai PENG Yaxin LI Ying College of Vehicles and Energy Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University

High strength aluminum alloy plate has a low elongation at room temperature, which leads to the forming of its components need a high temperature. Liquid or gas is used as the pressure-transfer medium in the existing flexible mould forming process, the heat resistance of the medium and pressurizing device makes the application of aluminum alloy plate thermoforming restricted. To solve this problem, the existing medium is replaced by the heat-resisting solid granules and the general pressure equipments are applied. Based on the pressure-transfer performance test of the solid granules medium, the feasibility that the assumption of the extended Drucker-Prager linear model can be used in the finite element analysis is proved. The constitutive equation, the yield function and the theoretical forming limit diagram（FLD） of AA7075 sheet are established. Through the finite element numerical simulation of hot granules medium pressure forming（HGMF） process, not only the influence laws of the process parameters, such as forming temperature, the blank-holder gap and the diameter of the slab, on sheet metal forming performance are discussed, but also the broken area of the forming process is analyzed and predicted, which are coincided with the technological test. The conical part whose half cone angle is 15° and relative height H/d0 is 0.57, is formed in one process at 250℃. The HGMF process solves the problems of loading and seal in the existing flexible mould forming process and provides a novel technology for thermoforming of light alloy plate, such as magnesium alloy, aluminium alloy and titanium alloy.

关键词： granules medium aluminum alloy sheet drawing hot forming forming limit diagram

来源：评论

学校读者我要写书评

暂无评论

Deployable unit 3R-3URU and its application in deployable truss antenna

引用

Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica 2017年第11期38卷 421285页

作者： Liu, Wenlan Xu, Yundou Yao, Jiantao Chen, Liangliang Wang, Hui 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 Xi'an710100 China

A spatial deployable unit 3R-3URU with one Degree of Freedom (DoF) is proposed. The DoF of the single closed-loop mechanism RURUR is analyzed, based on the screw theory and the modified G-K formula. The analytical expression for the velocities of active joints and passive joints of the mechanism RURUR are then established. According to the velocity expression and the structural characteristic that three RURUR mechanisms share their first and last revolute joints, the DoF of the 3R-3URU mechanism is derived. The geometrical relationship among the positions and directions of all joints is also obtained when the 3R-3URU mechanism has one DoF. Novel deployable mechanisms are obtained by applying the 3R-3URU mechanism to the 3RR-3RRR tetrahedral unit and a deployable truss antenna composed of the tetrahedral units, and the novel mechanisms have two types of DoFs: movement and orientation adjustment. DoF analysis and application of the 3R-3URU deployable unit are verified by the Adams software. The proposed deployable unit 3R-3URU has the advantages of one DoF, simple structure, and single type of joints, and can be applied to the supporting mechanism of deployable truss antennas with a curved surface to achieve a large folding ratio. © 2017, Press of Chinese Journal of Aeronautics. All right reserved.

关键词： Degrees of freedom (mechanics)

来源：评论

学校读者我要写书评

暂无评论

Kinematics and Dynamics Hessian Matrices of Manipulators Based on Screw Theory

引用

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

来源：评论

学校读者我要写书评

暂无评论

Mobility analysis of a deployable truss-antenna mechanism-Method based on link-demolishing and equivalent idea

引用

Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica 2017年第9期38卷 421188页

作者： Xu, Yundou Liu, Wenlan Chen, Liangliang Yao, Jiantao Zhao, Yongsheng Zhu, Jialong 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 National Education Yanshan University Qinhuangdao066004 China Xi'an710100 China

A method for Degree Of Freedom (DOF) analysis of spatial mechanisms with multiple coupled-loops is proposed based on the link-demolishing and equivalent idea, in view of the multi-loop coupling characteristic of a deployable truss antenna assembled by tetrahedral elements. The coupling constraint chain of the deployable tetrahedral element is removed, and the remainder is regarded as a parallel mechanism. The number and characteristic of the DOF of each output node are then analyzed using the screw theory, and the equivalent serial kinematic chain between the output nodes and the fixed node are then established. The equivalent mechanism of the deployable tetrahedral element is obtained by reconstructing the coupling constrained chain. The number and characteristic of the DOF of the equivalent mechanism are got using the modified G-K formula and the reciprocal screw theory, respectively. As a result, the kinematic characteristics of the tetrahedral element are known. The structure of the minimum composite unit and the large-scale truss deployable antenna are simplified, according to the equivalent mechanism and the combination of the tetrahedral elements. The numbers of the DOF of the minimum composite unit and the large-scale truss deployable antenna are derived on the basis of the geometric constraint equations. The simulation model for a deployable truss antenna assembled by 27 tetrahedral elements is built, and its DOF is verified. The result shows that the DOF of the antenna analyzed by the proposed method is correct. The method lays a foundation for further analysis of the kinematics and dynamics of similar type of antennas, providing a new idea for DOF analysis of other multi-loop coupling mechanisms. © 2017, Press of Chinese Journal of Aeronautics. All right reserved.

关键词： Antennas

来源：评论

学校读者我要写书评

暂无评论

Instability analysis of free deformation zone of cylindrical parts based on hot-granule medium-pressure forming technology

引用

Transactions of Nonferrous Metals Society of China 2016年第8期26卷 2188-2196页

作者： Miao-yan CAO Chang-cai ZHAO Guo-jiang DONG Sheng-fu YANG College of Mechanical Engineering Yanshan University Qinhuangdao 066004 China Key Laboratory of Advanced Forging & Stamping Technology and Science Ministry of Education Yanshan University Qinhuangdao 066004 China College of Vehicles and Energy Yanshan University Qinhuangdao 066004 China

The cylindrical part of sheet metal based on hot-granule medium-pressure forming (HGMF) technology was *** stress functions of the free deformation zone and the fracture instability theory were combined to establish the analytical expression of the critical pressure of punch. The results show that the active friction between the granule medium and the sheet metal, as well as the non-uniform internal pressure presented by the solid granule medium, can obviously improve the forming performance of the sheet metal. The critical pressure of punch increases with the increment of the friction coefficient between the granule medium and sheet metal, as well as the plastic strain ratio, whereas it decreases with the increase of the material-hardening exponent. Furthermore, the impact on the critical pressure from high to low order is the plastic strain ratio, the friction coefficient,and material-hardening exponent. The deep-drawing experiment with HGMF technology on AZ31B magnesium alloy sheet verified the instability *** words: hot-granule

关键词： hot-granule medium-pressure forming deep-drawing instability cylindrical part

来源：评论

学校读者我要写书评

暂无评论

Multi-PID controller parameters optimization of fast forging hydraulic press based on GA

引用

Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (science and technology) 2016年第8期47卷 2650-2660页

作者： Zhao, Jinsong Zhang, Yang Cao, Xiaoming Yao, Jing Key Laboratory of Advanced Forging & Stamping Technology and Science Ministry of Education of China Yanshan University Qinhuangdao066004 China Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Qinhuangdao066004 China

Parameters optimization method of multi-PID controller based on improved genetic algorithm was presented in response to the mismatch problems between PID parameters and working conditions and the improvement in forging precision. The expert database of parameter adjustment was established for different working conditions to optimize speed forging hydraulic press control characteristics. Firstly, the mathematical model of electro-hydraulic servo system controlled independently by Four-channel-load ports was founded based on the mechanism modeling method. On this basis, the identification experiment based on 0.6 MN fast forging hydraulic press electro-hydraulic servo system experimental platform was completed. Secondly, the parameters of PID controller were optimized by improved genetic algorithm under different working conditions, and the effectiveness of the genetic algorithm was analyzed via simulation. Finally, the control effect of optimized PID was verified on 0.6 MN fast forging hydraulic press electro-hydraulic servo system experimental platform. The results show that multi-PID controller optimized by genetic algorithm makes forging precision of fast forging hydraulic press system improved to ±1 mm, which can widely improve the adaptability in different work conditions. © 2016, Central South University Press. All right reserved.

关键词： Controllers

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

Effects of heat treatment on microstructure and properties of stainless clad plate

Effects of heat treatment on microstructure and properties o...

引用

International Conference on advanced Materials and Engineering Materials, ICAMEM 2016

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

ISBN: (纸本)9783038357018

The effect of heat treatment on microstructure and properties of Q345R/304 clad plate was studied. The microstructure of the base layer was analyzed by metallographic microscope and scanning electron microscope, and mechanical properties such as tensile, shear and impact were investigated after heat treatment. The chromium content in the compound interface was analyzed after heat treatment through spectrum analysis technology. The results show that heat treatment affects the mechanical properties and corrosion resistance of stainless clad plate significantly. After air cooling, the microstructure of the base layer consi+sts of ferrite and pearlite, the strength of clad plate is low, and the corrosion resistance is poor. After oil cooling to 450°C and air cooling, the microstructure of the base layer consists of bainite, ferrite and a small amount of pearlite. The strength and plasticity of clad plate can meet the application requirements and the corrosion resistance is excellent as well. © 2016 Trans Tech Publications, Switzerland.

关键词： Microstructure

来源：评论

学校读者我要写书评

暂无评论

Isomap and intrinsic mode function feature energy-based multi-fault recognition method of rolling bearing

引用

ICIC Express Letters 2016年第2期10卷 279-285页

作者： Jiang, Wanlu Wang, Zhenwei Zhu, Yong Hu, Haosong Zhang, Bang Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Qinhuangdao China Key Laboratory of Advanced Forging & Stamping Technology and Science Ministry of Education Yanshan University No. 438 Hebei Street Qinhuangdao China

Aiming at the nonlinear and non-stationary characteristics of vibrations from faulty parts, an approach was proposed to solve the problem by means of Isomap and intrinsic mode function (IMF) energy. The approach firstly conducts empirical mode decomposition to the vibration signals and calculates the energy of each IMF component to form feature vectors. Then Isomap reduces the vector dimensionality, by which bearing conditions can be visually diagnosed. And BP neural network is used to classify fault types. The approach was applied to measured vibration signals from normal condition and outer race, inner race and ball defects of rolling bearing. The results demonstrate that the approach can recognize fault type with high accuracy and high clustering. © 2016, ICIC Express Letters ICIC International.

关键词： Intrinsic mode functions

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：