ENGINEERING NEWS IN BRIEF
Issued by the Asian TOP Panel, October, 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) Development of nano manipulator based on an atomic force microscope for SEM operation (Source: JSME)
2) Development of New Securing method with use of a Taper Tack (Source: JSME)
3) Combustion and Turbulence database (Source: JSME)
4) Effect of input variability on the quality of laser shock processing (Source: KSME)
5) Development of frequency weighting function for Asian (Korean) people in vertical whole-body vibration; in comparison with ISO 2631-1 (Source: KSME)
6) Comparative analysis of the influence of labyrinth seal configuration on leakage behavior (Source: KSME)
1) Development of nano manipulator based on an atomic force microscope for SEM operation
Futoshi Iwata, Shizuoka University
We developed a novel nano manipulator based on an atomic force microscope (AFM) capable to be operated inside the sample chamber of scanning electron microscope (SEM). It is possible to observe the manipulation scene in the real time observation by using the SEM. Furthermore, the AFM manipulator was coupled with a haptic device for human interface. Thus, the operator can move the AFM probe at any position on the surface with feeling the interaction force detected by the cantilever on the sample surface according to the cantilever deflection. This system would be very applicable in various micro and nanometer-scale technology.
2) Development of New Securing method with use of a Taper Tack
Tetsu Kawashima, Shimokawa co.,ltd
Taper Tack method, which has been developed for assembling a printed circuit board, offers New Securing method that takes the place of a conventional coil screw focused on reinforcement of a screw.
The Taper Tack method is to embed a precisely machined top, which has 1/20 taper and flange, into a tapered hole as the same shaped as the top by force fitting, forming the hole with a forming tool.
Thus it holds tightly between a lower surface of the flange of the top and an outside periphery of taper by contact, preventing the top from turning together with the screw due to friction force. It is dual-surface hold type securing method.
As features of the Taper Tack, comparing with conventional coil screw, even a not-skilled person can perform precise work in a short time for an insertion work using an exclusive tool, and also for the size of the applicable screw, a fine screw with less than 1 mm in diameter is applicable.
Furthermore this is a product considering environment because detaching is easy so that disassembly and reuse is possible, when different kinds of materials are used, the material can be easily separated.
For examples of application are stud bolt, standard pin, spring post, and bearing post and for materials such as stainless, aluminum and brass can be also used.
About member to be inserted, nonmetal material like resin is also available. In addition this is also available substitute for thin plate burring machining.
In near future, this Taper Tack application may be expected to use in wide range areas such as auto industries and aircraft industries as an auxiliary part of securing parts.
3) Combustion and Turbulence database
Yasuhiro Mizobuchi, Hiroyuki Abe, Japan Aerospace Exploration Agency (JAXA)
Large-scale and detailed numerical simulations of combustion and turbulence have been conducted at Japan Aerospace Exploration Agency (JAXA) using its supercomputer systems. The obtained numerical data are released on the public HP of JAXA.
The combustion database is the result of a highly resolved simulation of a lifted flame formed around a subsonic hydrogen jet injected into atmosphere from a round nozzle. The computation was carried out in 2004 using JAXA's former supercomputer system. The simulation with detailed chemistry and transport properties using 200million grid points revealed the flame structure. The database includes various combustion phenomena to be investigated and utilized for combustion modeling.
The turbulence database has been obtained from DNS (Direct Numerical Simulation) of fully developed turbulent channel flows at Reynolds numbers up to Re=41,400. The DNS for Re=41,400 required about 1.4 billion grid points, which was the largest-scale high Reynolds-number simulation in 2003 in this configuration. The latter simulation exhibits typical features of high Reynolds-number wall-bounded turbulent flows (e.g. large-scale structures of high- and low-speed regions and hairpin-like vortices). The database is expected to be utilized for the development of turbulence models and for the calibration of turbulence measurement techniques.
4) Effect of input variability on the quality of laser shock processing
Abul Fazal M.
Arif King Fahd University of Petroleum & Minerals
Laser shock processing (LSP) involves high-energy laser radiation combined with suitable overlays to generate high-pressure pulses on the surface of the metal. The stress wave generated due to high pressure pulses propagates into the material causing the surface layer to yield and plastically deform, and thereby, develop a significant residual compressive stress in the surface region of the substrate material. The developed compressive stress field is beneficial to improve surface properties such as fatigue, wear, and corrosion. To improve the understanding of the shock hardening process, investigation into the physical processes involved is necessary. In the first part of this paper, the temporal variation in the pressure intensity and spot size is calculated by using a two-dimensional recoil pressure prediction model. Using an explicit non-linear FEA code, ANSYS LS-DYNA, the deformation behavior and residual stresses in the substrate material are predicted. In the second part, a probabilistic approach to the modeling and analysis of LSP is presented in this paper. Various factors that affect the probabilistic performance of the LSP are grouped into categories and a select number of factors known to be significant, for which the variability could be assessed, are modeled as random variables (such as recoil pressure, laser beam spot size, substrate material properties and others). The potential of the probabilistic approach in predicting the structural integrity of the laser-shocked components is addressed.
5) Development of frequency weighting function for Asian (Korean) people in vertical whole-body vibration; in comparison with ISO 2631-1
Kun-Woo Kim, Min-Seok Kim and Wan-Suk Yoo
Pusan National University
In the field of 'human vibration', until now most frequency weighting functions have been derived from particular experiments whose subjects were only Western people. However, because of inherent differences (e.g., characteristic and shape of body parts, muscular and cellular tissue) between Western people and Asian people, frequency weighting function based on Asian people is required. An experiment was carried out to develop a frequency weighting function for the Korean people in vertical whole-body vibration, and to verify whether this weighting is acceptable in practical applications in comparison with ISO 2631-1. Ten male subjects of mean weight and height were tested for a posture similar to sitting in a passenger seat (footrest, upright and placement of the palms of hands on thighs, etc.) of a car. This experiment was performed using sinusoidal excitation in the range from 2 to 250 Hz, which was a combination of one-half and one-third octave bands at eight determined amplitudes. To guarantee the reliability and accuracy of the test, non-parametric statistics was adopted to resolve the fact that there was not enough of the sample. Furthermore, two methods were considered to make the frequency weighting function and equal sensation curves. The first method changes the amplitude at every fixed frequency, and the other assigns weighting values. Korean people showed the most sensitivity to vertical whole-body vibration at 6.3 Hz excitation, so much higher weighting factors than weighting factors of other frequencies must be assigned near that frequency.
6) Comparative analysis of the influence of labyrinth seal configuration on leakage behavior
Tong Seop Kim and Kyu Sang Cha
This study analyzed the influence of configuration and clearance on the leakage behavior of labyrinth seals. Both computational fluid dynamics (CFD) and an analytical tool were used to predict the leakage flow of two different (straight and stepped) seal configurations with various clearances. The predicted results were compared with experimental data. The CFD gives a better agreement with the experimental result than the analytical model on average. In the straight seal, the dependence of the discharge coefficient on the clearance is considerable, while it is much smaller in the stepped seal. The CFD captures the entire behavior sufficiently well, but the analytical model overpredicts the clearance dependence in the stepped seal. The CFD also predicts well the influence of the flow direction on the leakage flow. The advantage of the stepped seal over the straight seal becomes more evident as the clearance gets larger. As the clearance becomes sufficiently small, the advantage of the stepped seal reduces.
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