研究者詳細 - 奥村　大

論文 - 奥村　大

分割表示 177 件中 101 - 120 件目／全件表示 >>

The large scale finite element analysis of a charge air cooler using a homogenization method 査読有り

K. Iwahori, N. Ohno, D. Okumura, T. Muraki, S. Miyakawa

SAE Technical Paper 2013 巻 ( 01 ) 頁： 1212 2013年8月

チューブ-フィン構造体におけるフィン層の均質化弾性剛性（評価と検証）査読有り

岩堀恵介, 大野信忠, 村木友也, 奥村大, 宮川進

日本機械学会論文集Ａ編 79 巻頁： 89-99 2013年

Implicit iterative finite element scheme for a strain gradient crystal plasticity model based on self-energy of geometrically necessary dislocations 査読有り

R. Kametani, K. Kodera, D. Okumura, N. Ohno

Computational Materials Science 53 巻頁： 53-59 2012年

Homogenizaed elastic-viscoplastic behavior of anisotropic open-porous bodies with pore pressure 査読有り

N. Ohno, K. Ikenoya, D. Okumura, T. Matsuda

International Journal of Solids and Structures 49 巻頁： 2799-2806 2012年

弾性積層ダンボールの圧縮強度に微視構造の及ぼす影響の均質化解析査読有り

奥村　大，大野信忠，小野田孝行，曽我将孝

計算数理工学論文集 12 巻頁： 103-108 2012年

Plastic size effect analysis of lamellar composites using a discrete dislocation plasticity approach 査読有り

D. Okumura, N. Ohno, K. Yamaguchi

27 巻頁： 2040-2055 2011年12月

Influence of closed faces on compressive strength of open cell metallic foams 査読有り

Dai Okumura, Yuji Takahashi, Nobutada Ohno

Materials Research Innovations 15 巻頁： S61-S64 2011年

離散転位塑性法を用いたラメラ複合材料の均質化解析招待有り

奥村　大，大野　信忠

計算数理工学レビュー 2011-1 巻頁： 13-19 2011年

離散転位動力学解析のための均質化理論の定式化査読有り

奥村　大，大野信忠，片桐慶大

材料 59 巻 ( 2 ) 頁： 149-156 2010年2月

Yield and buckling behavior of Kelvin open-cell foams subjected to uniaxial compression 査読有り

Yuji Takahashi, Dai Okumura, Nobutada Ohno

International Journal of Mechanical Sciences 52 巻 ( 2 ) 頁： 377-385 2010年

幾何学的に必要な転位の自己エネルギーを考慮したひずみこう配結晶組成理論のための陰的有限要素方程式査読有り

小寺一輝，亀谷隆真，奥村　大，大野信忠

計算数理工学論文集 9 巻頁： 43-48 2009年

単軸圧縮を受けるケルビンオープンセルフォームの微視的座屈挙動査読有り

奥村　大，岡田篤志，大野信忠

材料 57 巻 ( 2 ) 頁： 126-133 2008年2月

Buckling behavior of Kelvin open-cell foams under [0 0 1], [0 1 1] and [1 1 1] compressive loads 査読有り

Dai Okumura, Atsushi Okada, Nobutada Ohno

International Journal of Solids and Structures 45 巻 ( 13 ) 頁： 3807-3820 2008年

Grain-size dependent yield behavior under loading, unloading, and reverse loading 査読有り

N. Ohno, D. Okumura, T. Shibata

International Journal of Modern Physics B 22 巻頁： 5937-5942 2008年

Higher-Order Stress Due to Self Energy of Geometrically Necessary Dislocations 査読有り

N. Ohno, D. Okumura

Key Engineering Materials 340-341 巻頁： 173-178 2007年

Three-dimensional microscopic interlaminar analysis of cross-ply laminates based on a homogenization theory 査読有り

Tetsuya Matsuda, Dai Okumura, Nobutada Ohno, Masamichi Kawai

International Journal of Solids and Structures 44 巻 ( 25-26 ) 頁： 8274-8284 2007年

* A homogenization theory of strain gradient single-crystal plasticity and its finite element discretization 査読有り

D. Okumura, Y. Higashi, K. Sumida, N. Ohno

International Journal of Plasticity 23 巻頁： 1148-1166 2007年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

In this study, a homogenization theory based on the Gurtin strain gradient formulation and its finite element discretization are developed for investigating the size effects on macroscopic responses of periodic materials. To derive the homogenization equations consisting of the relation of macroscopic stress, the weak form of stress balance, and the weak form of microforce balance, the Y-periodicity is used as additional, as well as standard, boundary conditions at the boundary of a unit cell. Then, by applying a tangent modulus method, a set of finite element equations is obtained from the homogenization equations. The computational stability and efficiency of this finite element discretization are verified by analyzing a model composite. Furthermore, a model polycrystal is analyzed for investigating the grain size dependence of polycrystal plasticity. In this analysis, the micro-clamped, micro-free, and defect-free conditions are considered as the additional boundary conditions at grain boundaries, and their effects are discussed.

* Higher-order stress and grain size effects due to self-energy of geometrically necessary dislocations 査読有り

N. Ohno, D. Okumura

Journal of the Mechanics and Physics of Solids 55 巻頁： 1879-1898 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

The self energy of geometrically necessary dislocations (GNDs) is considered to inevitably introduce the higher-order stress work-conjugate to slip gradient in single crystals at small strains. It is pointed out that this higher-order stress changes stepwise in response to the in-plane gradient of slip, and thus significantly influences the onset of initial yielding in polycrystals. The self energy of GNDs is then incorporated into the strain gradient plasticity theory of Gurtin (J. Mech. Phys. Solids 50 (2002) 5). The resulting theory is applied to 2D and 3D model crystal grains of size D, leading to the D-1-dependent term of grain yielding with a coefficient determined by grain shape and orientation. This size effect term, which is also derived from a simple energy equation, is discussed using published experimental data of several polycrystalline metals. It is thus shown that the self energy of GNDs quantitatively accounts for not only the grain size dependence of initial yield stress but also the dislocation cell size dependence of flow stress in the submicron to several-micron range of grain and cell sizes.

Long wave-length buckling of periodic open-cell foams subjected to uniaxial compression 査読有り

D. Okumura, A. Okada, N. Ohno

Key Engineering Materials 345-346 巻頁： 81-84 2007年

Microscopic interlaminar stress analysis of CFRP cross-ply laminate using a homogenization theory 査読有り

T. Matsuda, D. Okumura, N. Ohno, M. Kawai

Key Engineering Materials 340-341 巻頁： 1043-1048 2007年

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