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Mechanism and Inhibition of Grain Coarsening of Al-Mg-Si Alloy in Hot Forming

Journal of Harbin Institute of technology(New Series) 2013年第3期20卷 67-74页

作者： Ying-Ping Guan Zhen-Hua Wang Bin Wu Wei-Xin Wang Wan-Tang Fu Key Laboratory of Advanced Forging & Stamping Technology and Science(Yanshan University) Ministry of Education of China College of Mechanical Engineering and Applied Electronic Technology Beijing University of Technology CITIC Dicastal Wheel Manufacturing Co. Ltd. State Key Laboratory of Metastable Materials Science and Technology Yanshan University

A high-Ti 6061 alloy was rolled with strains up to 0. 8 - 2. 0 and at 350 - 550 ℃ . Microstructures that developed during deformation and subsequent solution heat treatment (SHT) were observed by using optical and transmission electron microscopy. Microstructure evolution during SHT depends mainly on the initial rolling temperature,and it was found that the higher this temperature is,the coarser the grains are. After rolling at 400 ℃ ,well-defined cells and subgrains were formed, which induced further sites for recrystallization nucleation during subsequent SHT. The recrystallization mechanism was found to be subgrain rotation,with a final grain size smaller than 200 μm. Increasing the rolling temperature to 500 ℃ results in a low density of dislocations distributed uniformly in the deformed matrix and fewer nucleation sites during subsequent SHT. The recrystallization mechanism is grain boundary bulging,while the final grain size approaches several millimeters. Finally,a hot forming process of high-Ti 6061 alloy for inhibiting grain coarsening was proposed,and verified by experiments.

关键词： aluminum alloy grain size recrystallization nucleation mechanism

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Forced responses of field modulated magnetic gear system

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ICIC Express Letters 2014年第7期8卷 2025-2030页

作者： Yuan, Xiaoming Zhang, Lijie Du, Bing Hao, Xiuhong Key Laboratory of Advanced Forging and Stamping Technology and Science Ministry of Education of China Yanshan University No. 438 Hebei Ave. Qinhuangdao 066004 China Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University No. 438 Hebei Ave. Qinhuangdao 066004 China School of Mechanical Engineering Yanshan University No. 438 Hebei Ave. Qinhuangdao 066004 China

Considering the torque ripples on the rotors, the dynamic model and the dynamic differential equations of field modulated magnetic gear (FMMG) system are founded. When the excitation frequency is close to a certain natural frequency of FMMG system, the expressions of the forced responses are deduced and the laws of the resonance responses are discussed. Results show that the amplitude of only a certain degree of freedom is always much bigger than others, because the electromagnetic coupling stiffnesses are weaker than the supporting stiffnesses. Forced responses of FMMG system can provide the theoretical basis for the parameter optimization during designing. © 2014 ISSN 1881-803X.

关键词： Dynamic models

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Design of a new solution for the wheeled hopping robot

Design of a new solution for the wheeled hopping robot

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UKACC International Conference on Control (CONTROL)

作者： Jingjing Liu Hongbo Wang Hongnian Yu Lili Zhang Luige Vladareanu Adrian Bruja Gal I. Alexandru Parallel Robot and Mechatronic System Laboratory of Hebei Province Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Qinhuangdao China College of Electrical Engineering Yanshan University Qinhuangdao China School of Design Engineering and Computing Bournemouth University Poole UK Robotics and Mechatronic Department Institute of Solid Mechanics Bucharest Romania

In recent years many researchers are trying to combine wheeled movement with legged movement or hopping movement to strengthen the robots adaptability to environment. Hybrid robots are playing a more and more important role in our modern life. However, their controls are mostly complicated. So in this paper we present a new solution for the wheeled hopping robot. Based on the mechanical design, this robot has two movement modes: wheeled and hopping movement mode. While the center of gravity of the mechanism is under the wheels center, the wheeled hopping robot which is like a tumbler can keep its stability even when the wheels' velocity is zero. In this paper, we firstly introduce the description and design of the wheeled hopping robot. Then we explain how to choose the robot parameters and lastly we describe, how the robot through hopping, successfully traverses obstacles and ditches.

关键词： Mobile robots Shafts Wheels Springs Robot kinematics Force

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Investigation on the microstructures and tensile properties of TA15 titanium alloy thick-wall parts formed by laser rapid forming process

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2012 International Conference on Advances in Materials science and Engineering, AMSE 2012

作者： Xi, Mingzhe Key Laboratory of Advanced Forging and Stamping Technology and Science Yanshan University Ministry of Education of China Qinhuangdao City 066004 Hebei Province China

ISBN: (纸本)9783037855997

TA15 titanium alloy thick-wall parts have been deposited by Laser rapid forming (LRF) process. In this paper, a new overlap method between two adjacent laser tracks has been used to deposit the thick-wall titanium part. Results showed that the LRFed thick-wall titanium part was good in shape by using the new overlap method. The microstructure of the LRFed titanium alloy primarily consists of columnar prior-beta grain, which is perpendicular to the substrate resulting from directionally solidification. It also could be observed that the size of alpha phase increased with increasing laser power and decreasing scanning velocity. Tensile properties of LRFed titanium was slightly lower than that of the wrought annealed TA15 titanium alloy, after the heat-treatment of 940°C/1h/AC, the heat-treated titanium alloy showed good tensile properties which were equivalent to that of the wrought annealed TA15 titanium alloy. © (2013) Trans Tech Publications, Switzerland.

关键词： Microstructure

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Simulation on the transient thermal stress field of the wall-shaped part deposited by laser direct metal powder deposition

Simulation on the transient thermal stress field of the wall...

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2012 International Conference on Biomaterial and Bioengineering, ICBB 2012

作者： Xi, Mingzhe Key Laboratory of Advanced Forging and Stamping Technology and Science Yanshan University Ministry of Education of China Qinhuangdao City 066004 Hebei Province China

ISBN: (纸本)9783037855973

A thermo-kinetic model for the transient thermal stress field of the wall-shaped part produced using laser direct powder deposition process is developed. In case of numerical modeling, the capabilities of ANSYS parametric design language and the the 'birth and death' element technique were employed. The distribution of the thermal stress of the wall-shaped part at different time was calculated by the model. Results show that during process, the X-direction thermal stress within top layer of the wall-shape part and that within the interior deposited layers of the wall-shape part was tensile stress and compressive stress, respectively. The deformation of the wall-shaped part and base plate was also calculated. © (2013) Trans Tech Publications, Switzerland.

关键词： Finite element method

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Kinematics and statics analysis of a novel 4-dof parallel manipulator with two SPS legs and a PUP composite leg

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ICIC Express Letters 2014年第12期8卷 3445-3451页

作者： Lu, Yi Zhang, Xiuli Hu, Bo College of Mechanical Engineering No. 438 West Hebei Street Qinhuangdao China Hebei Vocational and Technical College of Building Materials Qinhuangdao China Parallel Robot and Mechatronic System Laboratory of Hebei Province No. 438 West Hebei Street Qinhuangdao China Key Laboratory of Advanced Forging and Stamping Technology and Science Ministry of Education Yanshan University No. 438 West Hebei Street Qinhuangdao China

A novel 4-degree of freedom parallel manipulator with two spherical joint-prismatic joint-spherical joint (SPS) active legs and a prismatic joint-universal joint-prismatic joint (PUP) composite leg is proposed and its kinematics and statics are studied. 1. Its structure constraint is analyzed, and formulae for solving the inverse displacement are derived. 2. The formulae for solving velocity, acceleration and active/constrained forces are established. 3. A workspace is constructed. 4. The analytic results are verified by its simulation mechanism. © 2014.

关键词： Kinematics

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Research on the Relationship between Classic Denavit-Hartenberg and Modified Denavit-Hartenberg

Research on the Relationship between Classic Denavit-Hartenb...

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International Symposium on Computational Intelligence and Design, ISCID

作者： Hang Wang Hanghang Qi Minghui Xu Yanhua Tang Jiantao Yao Xuedong Yan Ming Li Shanghai University Haitian Plastics Machinery Ltd. Ningbo HAITIAN Drive Systems Co. Ltd. Yanshan University Parallel Robot and Mechatronic System Laboratory of Hebei Province Key Laboratory of Advanced Forging & Stamping Technology and Science Yanshan University Department of Chemistry Northeast Normal University NINGBO VEKEN BATTERY CO. LTD

ISBN: (纸本)9781479970063

Currently, homogeneous transformation method has been widely used for its advantages in robot. Its more commonly used modeling methods are classic Denavit-Hartenberg method and modified Denavit-Hartenberg method, but the relationship between the two is very few devoted. Then, the use area is limited. Therefore, the relationship between classic Denavit-Hartenberg method and modified Denavit-Hartenberg method for robotics research has important practical significance. Based on this, the geometric representations of classic Denavit-Hartenberg method and modified Denavit-Hartenberg method are described respectively, the models of link parameters are built by the two, and the corresponding transformation matrix is deduced. The relationship between classic Denavit-Hartenberg method and modified Denavit-Hartenberg method is researched deeply, and the relational expression of classic Denavit-Hartenberg method and modified Denavit-Hartenberg method is obtained. The research results of this paper are useful for the robot kinematics, dynamics and control algorithms.

关键词： Joints Kinematics Heuristic algorithms Service robots Robot kinematics Mechatronics

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Numerical Simulation and Analysis to the behavior of Inner Hole Defect of Integral Top Cover for Pressure Vessel

Numerical Simulation and Analysis to the behavior of Inner H...

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2013 2nd International Conference on Manufacture Engineering,Quality and Production System(ICMEQP 2013)

作者： Zhaoqing Yu Shaomin Nie Shaoyin Qi Rongsheng Qi Xingang Liu Miao Jin Key Laboratory of Advanced Forging & Stamping Technology and Science (Yanshan University) Ministry of Education of China

The integral top cover for nuclear reactor pressure vessel is an important force component in the pressure vessel. It works under the HPHT and radiation long time, which increases forging difficultly and needs extremely high quality. Due to the effect of bi-directional tensile stress in spherical part during the shape forming stage of the integral top cover, it is easy to make holes and other defects of the blank extend. Then, it is necessary to study the behavior of the inner hole defect of integral top cover. This paper, by numerical simulation technology, concrete analyses the volume of the hole defect, the size of the hole defect and variation of the hole edges in the stress-strain fields during the shape forming stage of the integral top cover. It researches the control scope of the original size of blank holes when the integral top cover forging meet the requirements of the flaw detection. Research results show that, according to the requirements of volume and maximum size permissible value, the diameter of holes in the integral top cover blank should be respectively less than 1.8 mm, 1.5 mm.

关键词： Integral top cover Hole defect Numerical simulation analysis Permissible value

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Reliability prediction method of hydraulic system by fuzzy theory

Reliability prediction method of hydraulic system by fuzzy t...

引用

6th IFAC Symposium on Mechatronic Systems, MECH 2013

作者： Chen, Dongning Yao, Chengyu Feng, Zhongkui Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Qinhuangdao China Key Laboratory of Advanced Forging and Stamping Technology and Science Yanshan University Ministry of Education of China Qinhuangdao China Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University Qinhuangdao China

ISBN: (纸本)9783902823311

The hydraulic system's reliability is a key factor to ensure the reliable operation of equipment and it is very important to evaluate reliability of hydraulic system. The paper describes a reliability prediction method that may be used to evaluate the reliability of hydraulic systems for industrial applications. The proposed method takes advantage of fuzzy set theory. The aim of this method is to minimize the deficiencies of the traditional reliability prediction methods treating a failure rate as fixed value due to insufficiency practice data. Triangular fuzzy number and Gaussian fuzzy number are used in the application of this prediction method, where environmental factor, derating factor, and other factors are considered. Finally, an example of type crane's hydraulic system is given to verify the feasibility and practicability of the method. © 2013 IFAC.

关键词： Fuzzy set theory

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Reliability optimization of multi-state hydraulic system based on T-S fault tree and extended PSO algorithm

Reliability optimization of multi-state hydraulic system bas...

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6th IFAC Symposium on Mechatronic Systems, MECH 2013

作者： Yao, Chengyu Wang, Bin Chen, Dongning Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University Qinhuangdao China Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Qinhuangdao China Key Laboratory of Advanced Forging and Stamping Technology and Science Yanshan University Ministry of Education of China Qinhuangdao China

ISBN: (纸本)9783902823311

In order to overcome the difficulty of constructing the multi-state system's reliability optimization model, and the shortage of premature convergence of PSO (Particle Swarm Optimization) algorithm, a new reliability optimization method based on T-S fault tree and EPSO (Extended PSO) algorithm is proposed. According to the T-S fault tree and T-S rules of the events, the multi-state system reliability optimization model is constructed, at the same time, given constraint conditions on the system cost, weight and volume, and combined with the death penalty to construct the fitness function. Furthermore, EPSO algorithm based on the attraction and repulsion forces in the artificial physics is applied to the reliability optimization of multi-state hydraulic system. Comparing with PSO algorithm, the results of EPSO algorithm are in a better performance in obtaining global optimal solution. © 2013 IFAC.

关键词： Trees (mathematics)

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