鋼構造物を対象とした弾塑性解析への異種要素を接続したモデル化手法の適用  [in Japanese] APPLICATION OF NUMERICAL PROCEDURE FOR CONNECTING STRUCTURAL AND CONTINUUM ELEMENTS TO ELASTOPLASTIC ANALYSIS FOR STEEL STRUCTURES  [in Japanese]

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Abstract

部材の接合部分や角部近傍では応力集中が発生しやすいため,部材の降伏を評価する弾塑性解析が重要となる.そのような構造物の離散化に構造要素を適用すると,塑性域における金属材料の非圧縮状態が考慮されず,妥当な計算結果が得られるとは限らない.本研究では,Nitsche法に基づく異種要素の接続手法を鋼構造物のモデル化に適用する.本手法では,部材の接合部など角部を含む接続境界において,メッシュ分割を工夫することで妥当な計算結果が得られる.また,接続部分の界面に塑性域が進展するような状況では,シェル要素とソリッド要素で表現できる応力状態の相違から応力ベクトルが不連続となり,数値計算が不安定になる.そのため,異種要素を接続するモデル化手法は,各領域内に塑性域が留まる状況のもとで,弾塑性問題に適用すべきである.

In the finite element analysis, it is important to evaluate the local behavior at the portion where the thickness is discontinuous or near the corners. If such structure is discretized with structural elements, the numerical results are often unreliable, because the plane stress condition is assumed in the transverse direction and the incompressibility could not be considered appropriately. Thus, the authors proposed that the effective procedure of discretizing the model is to connect shell and solid elements properly by using Nitsche's method.<br>When the different types of elements are connected at the boundary including corners, the stiffness near such boundary may become larger than that of the model discretized with only one type of element. Thus, the authors propose the approach to avoid this problem by improving the mesh geometry near the boundary.<br>The proposed procedure can be applied to the elastoplastic problems, but it is necessary to divide the domain so that the plastic region does not progress on the connecting interface. This is because the numerical calculation becomes unstable due to the disorder of the stress state when discontinuous stress state is connected.<br>This paper presents a numerical procedure for connecting shell and solid elements in elastoplastic problems. In the proposed approach, shell and solid elements can be coupled with reasonable deformation near the connecting interface, only when the plastic range is not included on the connecting interface.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. A2 (Applied Mechanics (AM))

    Journal of Japan Society of Civil Engineers, Ser. A2 (Applied Mechanics (AM)) 74(2), I_147-I_158, 2018

    Japan Society of Civil Engineers

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