ENGINEERING NEWS IN BRIEF
Issued by the Asian TOP Panel, November, 2009
The Chinese Mechanical Engineering Society (CMES)
The Japan Society of Mechanical Engineers (JSME)
The Korean Society of Mechanical Engineers (KSME)
The Institution of Engineers, Indonesia (PII)
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 JSME for the year 2009.
1) A new concept of electromagnetic rotating motor for future aero propulsion (Source: JSME)
2) Field experiments of Network Robot Platform (Source: JSME)
3) Control of PCCI Combustion Using Blended Fuel (Source: JSME)
4) A Liquid Micro Rate Gyroscope using an ECF-jet (Source: JSME)
5) Affection of Assembly Temperature on Thermal Fatigue Life (Source: CMES)
6) Experimental Research on Boundary Slip of Confined Ligquids at Micro/nano Scale and Effect of Shear Rate (Source: CMES)
7) Research on Environment Test Voltage Loading Method of Electrical Connector in Vacuum (Source: CMES)
8) Analysis of plating grain size effect on whisker (Source: KSME)
9) Large deformation and mechanics of flexible isotropic membrane ballooning in three dimensions by differential quadrature method (Source: KSME)
10) Effect of moisture absorption on damping and dynamic stiffness of carbon fiber/epoxy composites (Source: KSME)
1) A new concept of electromagnetic rotating motor for future aero propulsion
Keiichi Okai, Japan Aerospace Exploration Agency (JAXA)
To realize an aircraft propulsion system with much higher environmental compatibility than today, an electric fan system is favored. Presently, heavy weight of electric engines with fuel cells in relation to output has prevented fuel cells from being utilized for aircraft engines. In this article, a new concept of an electromagnetic rotating motor is introduced which has a potential for realizing electric fan aero propulsion system. The keys to developing the motor are "weight saving", "making torque (turning force) more efficient" and "improvement in energy efficiency". To satisfy these three conditions, we designed an outer linear driving type motor system in place of the conventional axial rotation fan. The mechanism of the concept is briefly explained and results of concept verification test are described. Possible configurations of aero propulsion system are schematically shown and a potential to utilize cryogenic status of the promising hydrogen fuel is described. In addition, other possible applications of the present concept are suggested.
2) Field experiments of Network Robot Platform
Shin-yo Muto, NTT Cyber Solutions Laboratories
In this topic, we introduce the basic framework of Network Robot Platform (NR-PF), assuming the guide service by robots in a shopping mall or an amusement park, as a target application. This platform has three layers, database, area management gateway and connection unit. Database system manages service, user and robot database. Area management gateway allocates the service to the robot, based on 4W information (Who/When/Where/What). In this platform does not treat signal information. This platform treats abstracted information, user and robot 4W information. Then, connection unit integrates protocols. FDML and CrosSML protocol are used for the communication between connection unit and area management gateway. Through these experiments, many deferent-style robots cooperated for each service, using NR-PF. And we verified the functions of the platform. Then the results of field experiments shows that visible, virtual, unconscious robots, ubiquitous devices and electronic tag-PF can be integrated by the NR-PF, and that four applications can be implemented on the NR-PF.
3) Control of PCCI Combustion Using Blended Fuel
Yoshimitsu Kobashi, Kanazawa Institute of Technology
The ignitability and volatility of hydrocarbons depend on their carbon number. By blending two components which have different carbon number, the mixture is able to have unique characteristics. Such a blended fuel is applied to premixed charge compression ignition engines in order to control the ignition and combustion processes. Concretely speaking, this study aims to mitigate the steep combustion and suppress the wall-wetting by the fuel due to the facts that blending high volatile fuel improves the evaporation of low volatile one and the batch-distillation of the blended fuel distributes the each component vapor in the different region of fuel spray.
This paper briefly introduces this approach. In addition, as a feasibility study, the numerical simulation of a blended fuel spray is carried out by using multicomponent fuel spray model. The result predictably shows that this approach is effective in the cases in which the blended fuel consists of components having different volatility and ignitability.
4) A Liquid Micro Rate Gyroscope using an ECF-jet
Shinichi Yokota, Tokyo Institute of Technology
A novel concept of a liquid rate gyroscope using electro-conjugate fluid (ECF) is proposed and the prototype is fabricated. The ECF is a dielectric fluid which works here as a functional/smart fluid generating a powerful jet flow (ECF-jet) under a high DC electric field. The ECF liquid rate gyroscope proposed senses the drift of the liquid flow due to Coriolis force when an angular rate is applied. Although the sensing principle for angular rate is based on that of a conventional gas rate sensor, the proposed gyroscope has a much higher sensitivity because the density of the liquid is generally higher than that of a gas. In addition, the gyroscope is small in size because the ECF jet is generated only with a pair of tiny electrodes. In other words, the pumping part of the proposed gyroscope does not need mechanical moving parts, resulting in an ECF gyroscope more suitable for micro-applications than a gas rate sensor, which requires a pumping mechanism inside. The results of experiments show the ECF micro liquid rate gyroscope could possibly be a next generation standard of micro gyroscope for consumer products
5) Affection of Assembly Temperature on Thermal Fatigue Life
Tian Fang, Yan Ming, Tao Ke, Jiang Zhanli
Shenyang University of Technology
Mechanics mechanism of thermal fatigue and the affection of assembly temperature on thermal fatigue life were studied by using finite element method in consideration of the multilinear kinematic hardening of a material. It is discovered that an appropriate assembly temperature of specimen (material is ZL702A) can make its thermal stress cycle in elastic range, which can prolong the thermal fatigue life. The appropriate assembly temperature is related to mechanics properties of material and operating temperature, so reiterative computations are necessary to find an appropriate assembly temperature by the method that makes the maximal tensile stress smallest under conditions that the maximal compressive stress is less than the compressive yield point of material.
Key words: thermal fatigue life; assembly temperature; ZL702A; multilinear kinematic hardening
6) Experimental Research on Boundary Slip of Confined Ligquids at Micro/nano Scale and Effect of Shear Rate
Wang Xin, Zhang Xiangjun, Meng Yonggang, Wen Shizhu
In order to research the flow property of liquids between solid and liquid at micro/nano scale, a commercial atomic force microscope was modified by attaching a glass ball to the end of cantilever at micro/nano scale, which was used to investigate influence of approach velocity on boundary slip. Solid surface specimen was Si (100) verse deionized water. Results indicate that, when the distance between the glass ball and solid surface is below critical value, boundary slip will not affect the hydrodynamic force. The critical distance will decrease with the reducing of the velocity and it means boundary slip is dependent with velocity. The relationship between shear and boundary slip was discussed. It shows that boundary slip will occur only when the shear rate reaches some value.
Key words: micro/nano meter clearance; confined liquid; slip length; shear rate
7) Research on Environment Test Voltage Loading Method of Electrical Connector in Vacuum
Chen Wenhua, Wu Youy, and Gao Liang, Chen Zezong, Pan Jun
Zhejiang Sci-Tech University
For problems that different voltage loading method of electrical connector produces different electric field, the calculation model and method of electric field are set up with the electrostatic field theory in view that the decrease or breakdown of insulation resistance and dielectric strength induced by surface flashover cause failure of electrical connector in vacuum. Then in order to quickly and accurately evaluate the insulation life of electrical connector in vacuum environment, the optimized mathematical model of electric field is established under the condition of rated voltage by regarding the largest electric field and the most uniform electric field as objectives. Through extracting comprehensive evaluation function from the objectives by using signal-to-noise ratio of electric field, genetic algorithm is used to optimize the voltage loading method by converting multi objective to single objective. The optimal results show that the electric field not only increases about 50%, but also is more uniform, which provides the reference for the reliability evaluation of electrical connector in vacuum.
Key words: electrical connector; space environment; reliability testing; voltage loading
8) Analysis of plating grain size effect on whisker
Seung-Jung Shin1)/ Jae-Jung Kim2)/ Young Kap Son3)
1) Hansei University/ 2) Hanyang University/ 3) Andong National University
Whisker is a single beard-shape crystal filament, and it would be a main cause of producing electrical short circuits. Re-crystallization of both plating grain and base metal grain caused by internal and external stresses affects whisker growth. In this paper, we analyzed effect of grain size and structure of plating on whisker growth through whisker acceleration tests of ICs used in the electronic products. Samples with different package types, base metal, and plating thickness were used in the tests, and both structure and size of plating, and whisker were examined using SEM. From the test results, internal and external stresses produce more grain boundaries of plating when the grain size is smaller. And based on t-test, we found that there is a significant negative correlation between grain size and whisker growth. Therefore, smaller grain size of plating produces higher possibility of whisker occurrence, and whiskers grow in the grain boundaries of plating.
9) Large deformation and mechanics of flexible isotropic membrane ballooning in three dimensions by differential quadrature method
M. Mozaffari/A. A. Atai/N. Mostafa
Islamic Azad University, Iran
This paper presents a computationally efficient and accurate new methodology in the differential quadrature analysis of structural mechanics for flexible membranes ballooning in three dimensions under a negative air pressure differential. The differential quadrature method is employed to discretize the resulting equations in the axial direction as well as for the solution procedure. The weighting coefficients employed are not exclusive, and any accurate and efficient method such as the generalized differential quadrature method may be used to produce the methods weighting coefficients. A second-order paraboloid of revolution is assumed to describe the ballooning shape. This study asserts the accuracy, convergency, and efficiency of the methodology by solving some typical stability, straining analysis membrane problems, and comparing the results with those of the exact solutions and/or those of physical tests.
10) Effect of moisture absorption on damping and dynamic stiffness of carbon fiber/epoxy composites
Behzad Ahmed Zai1)/ M. K. Park1)/ H. S. Choi2)/ Hassan Mehboob1)/ Rashid Ali1)
1) Myongji University / 2) Korean Air
In this paper, the damping and dynamic stiffness of UHN125C carbon fiber/epoxy composite beam was experimentally measured. The effect of fiber orientation angle and stacking sequences on damping, resonance frequency, and dynamic stiffness was discussed with a focus on the effect of moisture absorption. Dried specimens were immersed in distilled water for a certain period to absorb water for 8, 16, and 24 d, respectively, and the moisture content absorbed in the specimen was measured. Furthermore, using the impact hammer technique, the measurements of dynamic responses were conducted on a cantilever beam specimen with one end clamped by bolts and metal plates. The damping properties in terms of loss factor were approximated by half-power bandwidth technique. The dynamic stiffness was evaluated using resonance frequency as a function of moisture content. The damping increased with the increase of moisture content; however, the dynamic stiffness reduced with the reduction of resonance frequency. The results of the dynamic stiffness were aided by measuring the dynamic strain using DBU-120A strain-indicating software. The increment in the dynamic strain strengthened the results obtained for dynamic stiffness.
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