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Parameter identification theory of a complex model based on global optimization method

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Science china(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2 & XU BingYe3 1 College of Automotive Engineering, South china University of technology, Guangzhou 510640, china 2 beijing research institute of mechanical and electrical technology, beijing 100083, china 3 Department of Engineering Mechanics, Tsinghua University, beijing 100084, china College of Automotive Engineering South China University of Technology Guangzhou China beijing research institute of mechanical and electrical technology Beijing China Department of Engineering Mechanics Tsinghua University Beijing China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 927°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization

APPLICATION OF GLEEBLE 1500 ON SUPERPLASTICITY

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Acta Metallurgica Sinica(English Letters) 2000年第2期13卷 514-520页

作者： B. Z. Bai X.J.Sun and L.Y.Yang 1) Department of Materials Science and Engineering, Tsinghua University, beijing 100084, china 2) beijing research institute of mechanical and electrical technology, beijing 100083, china

Gleeble1500 thermo-mechanical simulation machine is considered to be the first grade equipment in materials' research. However, it is seldom used in superplastic research. Perhaps this is because its specimen's heating method is not suitable to get large elongation. Elongation is an important parameter to evaluate superplasticity, but some other parameters such as the relationship between stress and strain rate are more important than elongation-it is an essential property to superplasticity. The stress-strain rate relationship can be very easily and very accu- rately got with Gleeble machine than with some other simlar equipment, and the relationship between microstructure and superplastic deformation is more easily examined with Gleeble. Present authors have got some new achievement in anisotropy, heterogeneity of superplastic deformation, and first put forward the regulation of dynamic equilibrium in microstructural evolution during superplastic deformation. All of these have been concluded from the experimental results mainly through Gleeble as well as the microstructural *** research work has got the support of National Natural Science Foundation and some international cooperation. Some theoretic and experimental results have been used in the practice of superplastic forming. Obvious effect of reducing cost and improving quality of formed parts has been achieved.

关键词： thermo-mechanical simulation superplasticity

Extrusion Upsetting Multiple Processing in Sandglass Die

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Rare Metals 2001年第1期20卷 62-65页

作者： Wenlin Lu, Yong Wang, Zezhou Feng, Jintao Hai (beijing research institute of mechanical & electrical technology, beijing 100083, china Academy of Machinery Science and technology, beijing 100044, china) 机械部北京机械所北京 100083 机械部机械科学研究院北京 100044

A new method of getting ultrafine grain size has been investigated, which is called 'Extrusion Upsetting Multiple Processing in Sandglass Die' or 'Sandglass Extrusion' (SE). Since the shape of tested billet can remain unchanged after SE, the billet can be extruded repeatedly in order to get large plastic strain. The ultrafine grain size can be obtained in the billet material due to the large plastic strain and the dynamic recrystallization during SE. The experiments on SE of Zn-5% Al alloy have been done. The SE technology, microstructures, microhardness and superplasticity of tested material after SE have been studied. The experimental results show that the equal-axial ultrafine microstructures can be introduced to the bulk test material during sandglass extrusion. The high strain rate superplasticity can be realized.

关键词： sandglass extrusion ultrafine grain large plastic strain superplasticity Zn-Al alloy

The precipitation and effect of nano nitrides in HSLC steel

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Science china(Technological Sciences) 2008年第7期51卷 989-998页

作者： FU Jie1, LIU YangChun1,2 & WU HuaJie1,3 1 School of Metallurgical and Ecological Engineering, University of Science and technology beijing, beijing 100083, china 2 Shougang technology research institute, Shougang (Group) Corporation, beijing 100041, china 3 Metallurgical Engineering research institute, University of Science and technology beijing, beijing 100083, china School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing China Shougang technology research institute Shougang (Group) Corporation Beijing China Metallurgical Engineering research institute University of Science and Technology Beijing Beijing China

The existing forms of N and Al in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process), the precipitation thermodynamics and kinetics of AlN, and its effects on structure and mechanical property are studied. The experimental results show that only a small quantity of nitrogen is com- bined into AlN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen. Aluminum-nitride is mainly precipitated during the period of slow air cooling after coiling, but not during rolling and water cooling. The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%―0.043%. The precipitation of AlN is not the main cause of grain refinement of HSLC steel produced by TSCR, nor is AlN the dominating precipitate that has precipitation strengthening effect. The nano nitrides are not pure AlN, but have complex compositions.

关键词： thin slab casting and rolling high strength low carbon steel AlN nano nitride precipitation strengthening

Mathematical Model for the Drying Process of Granular Materials in a Fluidized Bed

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 296-300页

作者： Xiulan Huai, Li Wang, Zhiyun Qu ( mechanical Engineering School, University of Science and technology beijing, beijing 100083, china Chemical Industry research institute of Shanxi, Taiyuan 030031, china) mechanical Engineering School University of Science and Technology Beijing Beijing 100083 China Chemical Industry research institute of Shanxi Taiyuan 030031 China

The experiment of granular materials, barley, drying in a fluidized bed was carried out to investigate the influence of the factors, inlet air temperature, air moisture, bed height and original moisture content of the dried materials on drying process. Based on the experimental data, a corresponding mathematical model is presented. As a conclusion, a higher inlet air temperature and a reasonable bed height should be used so as to increase the dring rate and to improve the product quality.

关键词： fluidization granular materials drying, experimental investigation mathematical model Information

Cutting Performance and Mechanism of RE Carbide Tools

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Rare Metals 2001年第3期20卷 197-201页

作者： Jianbing Cheng, Yufang Wu, Qixun Yu 1) Department of mechanical Engineering, beijing technology and Business University, beijing 100037, china 2) College of mechanical Engineering and Automation, beijing institute of technology beijing 100081, china 北京工商大学北京 100037 北京理工大学北京 100081

The research of rare earth elements (RE), added into cemented carbide tools, is one of the recent developments of new types of tool materials in china. Systematic experiments about RE carbides YG8R. (K30), YT14R (P20) and, YW1R (M10) were made to study on the cutting performance in comparison with non-RE carbides YG8, YT14 and YW1. The cutting experiments were as follows: tool life, cutting force, tool-chip friction coefficient and interrupted machining. The action of RE on the carbide materials and the cutting mechanism of the RE carbide tools in the cutting process were verified with the aid of SEM and energy spectrum analysis. Experimental results show that the RE carbide tools have a good overall performance.

关键词： rare earth elements cemented carbide tool cutting performance cutting mechanism

Effects of Cobalt on the Sintering Behavior of mechanically Activated Tungsten Powder

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Rare Metals 2001年第3期20卷 183-186页

作者： Chengchang Jia, Xiaoyang Liu, Xiuhu Guan, Xuekuan Su, Jun Zhao, Zizhang Xie 1) Materials Science and Engineering School, University of Science and technology beijing, beijing 100083, china 2) beijing research institute of Powder Metallutrgy, beijing 10005 北京科技大学北京 100083 北京科技大学北京 100083. 北京市粉末冶金所北京 100053 北京理工大学北京 100022.

Tungsten alloys were prepared with mechanically activated powder added microelement cobalt in order to improve the process and properties of alloys. Properties of alloys such as density, hardness and bending strength were measured. The results show that through mechanical activation, cobalt can accelerate the sintering process of these alloys By the combination of mechanical activation and adding microelement cobalt, tungsten alloys with higher density and better properties can be obtained.

关键词： powder metallurgy tungsten alloys cobalt mechanical activation sintering behavior

Influence of Hydrogen on the Microstructures and Superplasticity of a Ti_3Al-Nb Alloy

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Rare Metals 2001年第2期20卷 87-90页

作者： Hua Ding, Bingzhe Bai, Dingliang Wang, Dan Song, Caipei Zhang, Jianzhong Cui,Luyi Yang (Northeastern University, Shellyang 110006, china Tsinghua University, beijing 100084, china beijing research institute of mechanical and electrical technology, Be 东北大学辽宁沈阳 110006 清华大学北京 110006 机械部北京机电所北京 110006

The effect of hydrogen on the microstructures and superplasticity of a Ti3Al-Nb alloy was studied. The results showed that hydrogenation made the volume fraction of B2 phase increase and facilitated the dynamic recrystallization of the lath-like phase. The addition of hydrogen. reduced the flow stresses and made the maximum m value move to a lower temperature during the superplastic deformation. The superplastic deformation temperature of the alloy can be lowered by about 60 degreesC.

关键词： Ti,Al-Nb alloy thermohydrogen processing (THP) microstructure superplasiticity

THE METHOD OF PHOTOPLASTIC SIMULATION AND ITS APPLICATION ON COMPLICATED DEFORMATION

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Acta Metallurgica Sinica(English Letters) 2000年第1期13卷 411-420页

作者： G. S. Ren and C. C. Xu (beijing research institute of mechanical & electrical technology, beijing 100083, china)

The paper concisely introduced the hoopment of photoplastic simulation and the principle of its appli- *** of combine extrusion and strain distributin in the process of upsetting the cylinder with void were studied by this physical photoplasic simulation method. Some important informations obtained from the simulation experiment are helpful to understand the deformation law and the charac- teristics of material *** validity of the physical simulation method and the importance of com- bining the physical simulation method with numerical simulation method together were proposed in the paper.

关键词： photoplastic simulation,combine extrusion upsetting,deformation law