ENGINEERING NEWS IN BRIEF

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                  ENGINEERING NEWS IN BRIEF
                        E-Mail Newsletter

                               No.57
             Issued by the Asian TOP Panel, September 2006

           The Chinese Mechanical Engineering Society (CMES)
           The Institution of Engineers, Indonesia (PII)
           The Japan Society of Mechanical Engineers (JSME)
           The Korean Society of Mechanical Engineers (KSME)

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    According to the agreement made in the 2nd Asian TOP Panel Meeting,
the ENGINEERING NEWS IN BRIEF (E-mail newsletter) has now been edited
by the CMES for the year 2006.

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[Contents]

(1) Experimental Study on Chip Formation Mechanism Due to Shock of
     Ultra-High Speed Grinding (Source: CMES)
(2) Galvanneal Coating Exfoliating Analysis of Galvannealed Sheet Steel
     (Source: CMES)
(3) Three-Dimensional Optimization Design Of Hundred-Percent Reversible Subway Fan      (Source: CMES)
(4) Micro-siting Technique for Wind Turbine Generator by Using One PC
     (Source: JSME)
(5) Research on propulsion mechanism of a loach - PIV analysis of Anguilliform fish -      (Source: JSME)
(6) A framework for enhancing the machining skills (Source: JSME)
(7) A Study on Operation Characteristics of Planar-type SOFC System integrated with
     Fuel Processor (Source : KSME)
(8) Behavior of a Heavy Particle in the Shear Flow Near a Flat Wall (Source : KSME)
(9) Reference Stress Based Stress Analysis for Local Creep Rupture of T-pipe
     (Source : KSME)

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(1) Experimental Study on Chip Formation Mechanism Due to Shock of Ultra-High Speed      Grinding

   ZHAO Henghua GAO Xingjun Liaoning University of Petroleum & Chemical      Technology,
     CAI Guangqi School of Mechanical Engineering & Automation, Northeastern      University

According to the theory of ultra-high speed shock, the phenomenon of ultra-high speed grinding from the collision between grain and workpiece is researched. In order to study the chip formation mechanism in ultra-high speed grinding, the experimental study on ultra-high speed shock grinding about four kinds of the engineering material such as carbon steel, natural marble, spring steel and high speed tool steel are performed, which is used veritable amorphous carborundum and CBN grains that adhered to the head of bullet whose size is 7.62 mm as abrasive material, and used the 81 type rifle as accelerator and charger. Some valuable results in experiment of ultra-high speed grinding are acquired and the results are analyzed in detail. The experimental results indicate that in ultra high speed shock grinding the contact point is produced high temperature instantaneously which attached or exceeded its melting point, thereby, the material of the contact zone between the bullet and the steel plate becomes mobile phase and the flow material leaves the matrix and becomes abrasive dust under the action of the grain and shock wave. The phenomenon on chip formation due to shock of ultra-high speed grinding is found, so the chip formation mechanism due to shock of ultra-high speed grinding is studied and disclosed from the deeper level, and the accuracy of "the model of mechanism of chip-formation due to shock in quasi-fluid phase on super-high speed grinding" is verified.

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(2) Galvanneal Coating Exfoliating Analysis of Galvannealed Sheet Steel

     XU Chun LIN Zhongqin Automobile Manufacture Center, Shanghai Jiaotong      University

During double reverse olsen's forming, the galvanneal coating exfoliating is shot in multi burst mode by a camera, which shows that the exfoliating occurring time, location and amount are affected by the change of punch stroke distance. The self-developed auto rating system is used to evaluate the grades of coat exfoliating. It can be found that the compress strain of galvanneal coating has a relationship with punch stroke distance, and exfoliating behavior has a corresponding relationship with the compress strain. The exfoliating mainly occurs at the compress strain regions. The greater the strain is, the larger exfoliating amount is. The strains at different stages are stimulated by the means of FEM in order to compare actually exfoliating process. The results show the interesting relationship between exfoliating and strain, that is, the exfoliating occurs only when compress strain exceeds a certain limit. With the increasing of strain, the exfoliating amount becomes greater and greater. And when strain reaches its maximum and declines, the exfoliating would stop soon after.

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(3) Three-Dimensional Optimization Design Of Hundred-Percent Reversible Subway Fan

     TAN Chunqing CHEN Haisheng LIANG Xizhi
     Institute of Engineering Thermophysics, Chinese Academy of Sciences

Optimization design of a hundred-percent reversible axial fan is conducted by the method of three-dimensional optimization design based on design of experiment, flow analysis and blade profile modification. The results show that the performance of the fan is improved significantly without changes of diameter, rotation speed and tip clearance. At designed condition, the efficiency of positive rotating fan is 82.3% by 9.1% improved and the efficiency of negative rotating fan is 79.1% by 3.3% improved. The internal flow field of the fan is reasonable without obvious separations and back flows. The total pressure distribution at the fan outlet is improved as well. The performance of the fan at different flow rate is fine with the smooth performance curve. The three-dimensional optimization design of the axial fan is successfully validated by the experimental results.

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(4) Micro-siting Technique for Wind Turbine Generator by Using One PC

     Takanori UCHIDA, Kyushu University

A great reduction of CO2 becomes an urgent problem because it combats global warming now.The number of wind power generation facilities increases rapidly from several wind turbines to a large-scale wind farm in our country. The output of the wind turbine is proportional to the cube of the wind speed. Especially, the terrain in Japan is remarkably different from Europe and America. Therefore, it is highly important in Japan to choose a good site for wind turbines, because the spatial distribution of wind speed is quite complicated over steep complex terrain.
We are developing the unsteady numerical model called the RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, Computational Prediction of Airflow over Complex Terrain).The RIAM-COMPACT is based on the LES (Large-Eddy Simulation). The object domain of the RIAM-COMPACT is from several m to several km.
In the present paper, the feature and usage of the RIAM-COMPACT as a software package is described, and an actual application example is shown. Because the local change in the wind can be reproduced in animation in the RIAM-COMPACT, it is expected to use the RIAM-COMPACT as a preliminary investigation tool of the construction of the wind farm.

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(5) Research on Propulsion Mechanism of a Loach - PIV Analysis of Anguilliform Fish -

     Katsuya NAGAYAMA, Kyushu Institute of Technology

Loach has unique lifestyle, stays and swims at the bottom of water with locomotion, and can be a model of robot inspecting pipelines. Its propulsion mechanism was investigated by dynamic PIV (Particle Image Velocimetry). In case of 2 D flow field with shallow water, loach gains propulsion pushing water behind and leaving reverse Karman vortices. Improving PIV technique, interactions between body and water were also observed, and it was found that vortex shed from head side, is carried and grows along body, and finally is released smoothly by caudal fin. On the other hand, in case of 3 D flow in deep water, stereoscopic PIV results indicate tube type or a half ring vortex, which is quite different from 2 D vortex structure. Thus swimming mechanisms of a loach is becoming clear. Dynamic PIV is a strong tool for the research of Aqua-bio-mechanisms, and is expected to be applied to other aquatic lives to clarify their swimming mechanisms.

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(6) A Framework for Enhancing the Machining Skills

     Koji TERAMOTO, Osaka University

In this article, we propose a framework of support system based on the computational facility augmentation. A customizable and consistent task support environment is proposed to enhance the operational skills in machining. The environment has two features: one is a consistent scheme of information sharing in the task execution, the other is a systematic design of human customizable support environment. Human customization is expected to improve the operational skills effectively.
Based on this framework, the skills are stored not only in human brain, but also in customized environment configuration. We have developed several support software for milling operation, like an interactive operation planner, a machining simulator for preliminary machining evaluation and a machining state visualization system. These functional modules are organized to realize a consistent support of operators. A basic configuration of the software is defined by considering the human task execution. A thermal state visualization is also explained as an example of the machining state visualization.

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(7) A Study on Operation Characteristics of Planar-type SOFC System Integrated with      Fuel Processor

     Hyunjin Ji, Sungkwang Lim, Joongmyeon Bae KAIST
     Yungsung Yo KEPRI (Korea Electric Power Research Institute)

The solid oxide fuel cell (SOFC) is expected to be a candidate for distributed power sources in the next generation, due to its high efficiency and high-temperature waste heat utilization. In this study, the 5-cell SOFC stack was operated with pure hydrogen or reformed gas at anode side and air at cathode side. When stack was operated with diesel and methane ATR reformer, the influence of the H2O/C, O2/C and GHSV on performance of stacks have been investigated. The result shows that the cell voltage was decreased with the increase of H2O/C and O2/C due to the partial pressure of fuel and water, and cell voltage was more sensitive to O2/C than H2O/C. Next, the dynamic model of SOFC system included with ATR reformer was established and compared with experimental data. Based on dynamic model, the operation strategy to optimize SOFC-Reformer system was suggested and simulated.

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(8) Behavior of a Heavy Particle in the Shear Flow Near a Flat Wall

     Jaedal Jeong, Changhoon Lee Yonsei University

The motion of a small rigid particle in the shear flow near a stationary flat wall is investigated in the context of Stokes flow. The lift force proposed by Saffman and later modified by Mclaughlin and Mei is considered in the prediction of the particle motion far away from the wall. Later, the expression of the lift force is modified to take into account the effect of wall. In the analysis, gravity, lift and drag acting on a small rigid particle near the wall are taken into account. Both analytical and numerical results for the terminal velocities, distances from the wall and trajectories of the particle are presented. In addition, we extended the present analysis to turbulent near-wall flow in the vicinity of the wall.

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(9) Reference Stress Based Stress Analysis for Local Creep Rupture of a T-pipe

     Kyu In Shin, Kee Bong Yoon Chung Ang University
     Yun Jae Kim Korea University,

To investigate applicability of the reference stress approach as simplified inelastic stress analysis to estimate local creep rupture, detailed finite element stress analyses of a T-piece pipe with different inner pressure and system loading levels are performed. The reference stresses are obtained from the finite element (FE) limit analysis based on elastic-perfectly-plastic materials, from which the local reference stress for creep rupture is determined from R5. The resulting inelastic stresses are compared with elastic stresses resulting from linear elastic FE calculations. Furthermore they are also compared with the stresses from full elastic-creep FE analyses. It shows that the stresses estimated from the reference stress approach compare well with those from full elastic-creep FE analysis, which are significantly lower than the elastic stress results. Considering time and efforts for full inelastic creep analysis of structures, the reference stress approach is shown to be a powerful tool for creep rupture estimates and also to reduce conservatism of elastic stress analysis significantly.

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Editor : Tian Ruizhu
           The Dept. of Internationa Affairs
           Chinese Mechanical Engineering Society