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| 1.
論文（リポジトリ） |
論文（リポジトリ）
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仲村, 力也 ; 近藤, 了嗣 ; Nakamura, Rikiya ; Kondou, Ryouji
概要:
The thinning processing of crystal grain boundary lines and calculation of strain of crystal grains are programmed for e
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stimation of the non-uniform deformation behavior of crystal grains in polycrystalline material. The thinning processing of crystal grain boundary line is calculated by image processing based on Hilditch method. Logarithmic strains are calculated by measuring maximum distances of grain boundaries of respective grains at every degree interval from the loading direction. The strain distribution in all direction for a grain is approximated with an ellipse using the method of least squares and the principal strain are obtained as the long and the short axes of the ellipse. The calculation accuracy of these programs is examined in detailed.
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| 2.
論文（リポジトリ） |
論文（リポジトリ）
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末吉, 敏恭 ; 呉屋, 守章 ; 伊藤, 耿一 ; 宮城, 清宏 ; Sueyoshi, Toshiyasu ; Goya, Moriaki ; Ito, Koichi ; Miyagi, Kiyohiro
概要:
A plastic constitutive theory incorporating the directional dependence of the plastic strain increment dε^p on the stres
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s increment dσ' was proposed by Goya and Ito. The expression was given in terms of two transition parameters μ(α) and β(α) which denote the magnitude and the direction angle of the plastic increment, where α denotes the direction angle of the stress increment measured from a particular direction n_N, named "natural direction", in which the direction of the stress increment coincide with that of the plastic strain increment. In this report, a computer code for a finite element polycrystalline model is used for the numerical investigation of the variation of the two constitutive parameters μ(α) and β(α) of anisotropic plastic materials. The results show that the approximate functions for the two transition parameters are numerically determined and the direction dependence rule can be naturally extended for anisotropic plastic materials. It is also suggested that several quadratic functions used for classical plastic potential may be introduced for the natural direction potential whose normal is identical to the natural direction.
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| 3.
図書 |
図書
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Martin Fuchs, Gregory Seregin
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| 4.
論文（リポジトリ） |
論文（リポジトリ）
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佐々木, 知之 ; 呉屋, 守章 ; 宮城, 清宏 ; 糸村, 昌祐 ; 末吉, 敏恭 ; Sasaki, Tomoyuki ; Goya, Moriaki ; Miyagi, Kiyohiro ; Itomura, Shousuke ; Sueyoshi, Toshiyasu
概要:
Assuming a spherical void in an infinite rigid plastic material, Gurson proposed a yield function for isotropic porous s
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olids. It is, however, well known that the Gurson model gives harder response than those predicted by experimentation on actual porous solids. In numerical studies to check the validity of Gurson's model, most of the past researchers have introduced a cubic unit cell model, in which a spherical void is placed at the center of the cube. The cubic model can be a good approximation of a porous solid, if the void volume fraction is very small. The cubic model, however, may be not appropriate for the study of porous solids with high ratio of void volume fraction since the model automatically introduces an orthotropy effect due to the geometrically repetitive distribution of voids in three orthogonal axis directions. This research will propose a new unit cell model which is appropriate for the study of the yield functions for isotropic porous materials. The model is also favorable for the study of the anisotropic effect due to the void shape because the unit cell includes less of the anisotropy based on the distribution than the cubic model does.
論文 続きを見る |
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| 5.
論文（リポジトリ） |
論文（リポジトリ）
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呉屋, 守章 ; 伊藤, 耿一 ; 宮城, 清宏 ; 末吉, 敏恭 ; 糸村, 昌祐 ; Goya, Moriaki ; Ito, Koichi ; Miyagi, Kiyohiro ; Sueyoshi, Toshiyasu ; Itomura, Shosuke
概要:
A constitutive law of plastic deformation has been proposed by Goya and Ito, and can incorporate the stress increment di
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rectional dependence of plastic strain increment ε^p. The law is developed through the introduction of two transition parameters μ(α) and β(α), which denote the magnitude and the direction angle of the plastic strain increment, respectively, and are defined to be functions of the direction angle of the stress increment. In this report, the law is implemented in an F. E. M. code for deformation analysis. A plane strain tension problem is analyzed for investigation of the effect of these parameters on the occurrence of the shear band. The results show that the clear shear does not appear when the calculation is performed using B_
論文 |
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| 6.
図書 |
図書
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Wei Yang, W. B. Lee
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| 7.
図書 |
図書
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Y. Bai and B. Dodd
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| 8.
図書 |
図書
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K.S. Havner
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| 9.
図書 |
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W. Johnson and P.B. Mellor
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| 10.
図書 |
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by H.J. Frost and M.F. Ashby
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