著者
井上 智嗣 田中 満 萩原 良道
出版者
一般社団法人日本機械学会
雑誌
計算力学講演会講演論文集 (ISSN:1348026X)
巻号頁・発行日
vol.2006, no.19, pp.729-730, 2006-11-02

Direct numerical simulations (DNS) have been conducted for the heat transfer in pseudo-turbulence induced by small contaminated bubbles. The void fraction ranges from 1.5% to 9.0%. Air bubbles with a diameter of 500μm, are considered. We imposed a constant temperature gradient in the vertical or horizontal directions. Computational results show that the heat transfer in the case of vertical temperature gradient is highly enhanced by a bubble in pseudo-turbulence. With the increase in void fraction, the heat transfer is attenuated in the case of vertical gradient while the heat transfer is enhanced in the case of horizontal gradient.
著者
下田 昌利 塚田 聡
出版者
一般社団法人日本機械学会
雑誌
計算力学講演会講演論文集 (ISSN:1348026X)
巻号頁・発行日
vol.2010, no.23, pp.368-370, 2010-09-23

In this paper, we present a free-form optimization method for designing shell's form in order to control the vibration mode at a prescribed frequency to a target mode. With the free-form optimization method, an optimum shell with smooth free-form surface can be obtained without any shape parameterization. We introduce a squared displacements error norm at the prescribed surface as the objective functional to control the vibration mode to a desired one in a frequency response problem. It is assumed that the shell was varied in the normal direction to the surface and the thickness is constant. A non-parametric shape optimization problem is formulated, and the shape gradient function is theoretically derived using the material derivative method. The shape gradient function is applied to the shell surface as the pseudo traction force to vary the form. The calculated results show the effectiveness of the proposed method for the optimal free-form design of shell structures aiming at mode control.
著者
池川 正人
出版者
一般社団法人日本機械学会
雑誌
計算力学講演会講演論文集 (ISSN:1348026X)
巻号頁・発行日
vol.2010, no.23, pp."F-28"-"F-29", 2010-09-23

磁気ディスク装置(以下HDD)の内部では,ディスクが高速(例えば7,200min^<-1>)に回転するため,ディスク周りの空気が摩擦で引き摺られることにより台風並みの高速流(20-40m/s)が生じる。この高速流はアームやディスクに衝突して振動(FIV : Flow Induced Vibration)させ,アーム先端のへッドの位置決め精度を悪化させる大きな要因となっている。そこで,現在のHDDの開発では,この気流制御が重要な課題となっており,CFD(Computational Fluid Dynamics)を用いたCAEが活躍している。
著者
ナウィ アブ ハニパー 渡辺 一実
出版者
一般社団法人日本機械学会
雑誌
計算力学講演会講演論文集 (ISSN:1348026X)
巻号頁・発行日
vol.2000, no.13, pp.247-248, 2000-11-27

A cylindrically or radially fiber reinforced material is considered as a cylindrically anisotropic body. The stress solution for a cylindrically anisotropic body under a point force is obtained. This solution is a Green function for a cylindrically anisotropic body. An example of numerical calculation for stress distribution are illustrated.
著者
中曽根 祐司 松尾 唯史
出版者
一般社団法人日本機械学会
雑誌
計算力学講演会講演論文集 (ISSN:1348026X)
巻号頁・発行日
vol.2005, no.18, pp.275-276, 2005-11-17

The present study has applied Hori and Kameda's stress inversion method to the estimation of elasto-plastic stress distributions in Al-Mg polycrystalline materials. The method can estimate 2D elasto-plastic stress distributions from deformation distributions measured in a structure by using only the elastic moduli of the material of the structure. First, computer codes have been developed based on the present stress inversion method. Then, elasto-plastic 2D FEM analyses of stress concentration problems caused by elliptic holes and rectangular inclusions were made. Comparison of the results obtained by the FEM analyses and the stress inversion method showed that the stress inversion method can estimate elastic and elasto-plastic stress distributions from deformation/strain distributions with reasonable accuracy. Finally, the elasto-plastic stress distributions in Al-Mg were estimated by using deformation distributions measured by the digital image correlation method and it was found that stress concentration occurred near triple junctions of grain boundaries.