• Structural Engineering and Mechanics
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• 제15권1호
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• pp.83-114
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• 2003

A new simple 3-node triangular flat-shell element with standard nodal DOF (6 DOF per node) is proposed for the linear and geometrically nonlinear analysis of very thin to thick plate and shell structures. The formulation of element GT9 (Long and Xu 1994), a generalized conforming membrane element with rigid rotational freedoms, is employed as the membrane component of the new shell element. Both one-point reduced integration scheme and a corresponding stabilization matrix are adopted for avoiding membrane locking and hourglass phenomenon. The bending component of the new element comes from a new generalized conforming Kirchhoff-Mindlin plate element TSL-T9, which is derived in this paper based on semiLoof constrains and rational shear interpolation. Thus the convergence can be guaranteed and no shear locking will happen. Furthermore, a simple hybrid procedure is suggested to improve the stress solutions, and the Updated Lagrangian formulae are also established for the geometrically nonlinear problems. Numerical results with solutions, which are solved by some other recent element models and the models in the commercial finite element software ABAQUS, are presented. They show that the proposed element, denoted as GMST18, exhibits excellent and better performance for the analysis of thin-think plates and shells in both linear and geometrically nonlinear problems.

• 한국공간구조학회논문집
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• 제2권1호
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• pp.93-102
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• 2002

Pressure loads caused by gas, water and wind are the most important load cases in structural analysis. Often the pressure loads are approximated by constant directional loads since it is difficult to evaluate the exact value. However, the pressure load is defined as a displacement dependent one and it is necessary to consider the follower effects of the load in analysis procedure. In this study, the large deformation analysis considering geometrical nonlinearity for shell structures under pressure loads is presented. Finite element by using a three-node flat triangular shell element is formulated and the follower effects of the pressure load are included in the formulation. Some of results are presented for cantilevered beam under uniform external pressure and thin circular ring under non-uniform external pressure. The present results are in good agreement with the results available in existing literature and commercial software ABAQUS.

• Structural Engineering and Mechanics
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• 제68권4호
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• pp.385-398
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• 2018

In the present paper, we offer a new flat shell finite element. It is the result of the combination of a membrane element and a bending element, both based on the strain-based formulation. It is known that $C^{\circ}$ plane membrane elements provide poor deflection and stress for problems where bending is dominant. In addition, they encounter continuity and compliance problems when they connect to C1 class plate elements. The reach of the present work is to surmount these problems when a membrane element is coupled with a thin plate element in order to construct a shell element. The membrane element used is a triangular element with four nodes, three nodes at the vertices of the triangle and the fourth one at its barycenter. Each node has three degrees of freedom, two translations and one rotation around the normal. The coefficients related to the degrees of freedom at the internal node are subsequently removed from the element stiffness matrix by using the static condensation technique. The interpolation functions of strain, displacements and stresses fields are developed from equilibrium conditions. The plate element used for the construction of the present shell element is a triangular four-node thin plate element based on Kirchhoff plate theory, the strain approach, the four fictitious node, the static condensation and the analytic integration. The shell element result of this combination is robust, competitive and efficient.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.3-17
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• 2003

This paper deals with the problems and their possible solutions in the development of finite element for analysis of shell. Based on these solution schemes, a series of flat shell elements are established which show no signs of membrane locking and other defects even though the coarse meshes are used. In the element formulation, non-conforming displacement modes are extensively used for improvement of element behaviors. A number of numerical tests are performed to prove the validity of the solutions to the problems involved in establishing a series of high performance flat shell elements. The test results reveal among others that the high accuracy and fast convergence characteristics of the elements are obtainable by the use of various non-conforming modes and that the ‘Direct Modification Method’ is a very useful tool for non-conforming elements to pass the patch tests. Furthermore, hierarchical and higher order non-conforming modes are proved to be very efficient not only to make an element insensitive to the mesh distortion but also to remove the membrane locking. Some numerical examples are solved to demonstrate the validity and applicability of the presented elements to practical engineering shell problems.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2006년도 춘계 학술발표회 논문집 제3권1호(통권3호)
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• pp.256-264
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• 2006

This paper describes the formulation of rectangular flat shell element that is modeled with the six degree of freedoms including a rotational degree of freedom. The rectangular finite element matrix with a rotational degree of freedom is developed using a beam stiffness matrix and compared with other methods. The outputs of the quantity of vertical deflection of cantilever beam show us the improving evidence of the Frame-Shell finite element matrix in a calculation of vertical deflections of cantilever beam.

• 한국전산구조공학회논문집
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• 제23권4호
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• pp.409-415
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• 2010

본 논문에서는 플랫 플레이트 구조의 뚫림전단 거동을 평가할 수 있는 유한요소해석 모델을 제시하고 변수 해석을 통해 플랫 플레이트 구조의 뚫림전단 거동에 영향을 미치는 인자들을 파악함으로써 향후 현행 설계식 보정에 있어 기초자료를 제공함에 그 목적을 두었다. 전단변형을 고려하기 위해 Reissner-Mindlin 가정이 도입된 퇴화 쉘 요소를 선택하였으며, 철근콘크리트의 재료적 비선형 거동을 고려하기 위해 적층쉘 개념을 적용한 유한요소해석 모델을 제시하였다. 유한요소해석 모델의 신뢰성을 검증하기 위해 기존 실험결과와 비교하였으며, 그 결과 유한요소해석 모델이 실험결과를 비교적 잘 예측하는 것으로 나타났다. 제시한 유한요소해석 모델을 사용한 변수해석을 통해 휨 철근비와 슬래브의 두께가 증가할수록 플랫 플레이트의 전단강도 또한 증가하는 것을 알 수 있었다.

• 복합신소재구조학회 논문집
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• 제3권2호
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• pp.47-54
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• 2012

In this study, composite laminate cantilever type cylindrical shells with edge-stiffeners are analyzed. A versatile 4-node flat shell element which is useful for the analysis of shell structures is used. An improved flat shell element is established by the combined use of the addition of non-conforming displacement modes and the substitute shear strain fields. Two models by load conditions are considered. Load type A and B are loaded by point load at the free edge and line load respectively. A various parameter examples are presented to obtain proper stiffened length and stiffened thickness of edge-stiffeners. It is shown that the thickness of shell can be reduced minimum 30% by appropriate edge-stiffeners.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.27-34
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• 1998

A versatile flat shell element has been developed by combining a membrane element with drilling degree-of-freedom and a plate bending element. This element is formulated by the enhanced displacement field with the additional non-conforming displacement modes. Thus the element possesses six degrees-of-freedom (DOF) per node which permits an easy connection to other six DOF elements as well as the improvement of the element behavior. In plate bending part, this element is established by the combined use of the addition of non-conforming modes, the reduced (or selective) integration scheme, and the construction of the substitute shear strain fields. The achieved improvement may be attributable to the fact that the merits of these individual techniques are merged into the new element in a complementary manner. In membrane part, this element shows better membrane behavior as the nonconforming displacement mode is added to drilling mode.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.69-72
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• 2004

A new three-node triangular shell element based on higher order zig-zag theory is developed for laminated composite shells with multiple delaminations. The present higher order zig-zag shell theory is described in a general curvilinear coordinate system and in general tensor notation. All the complicated curvatures of surface including twisting curvatures can be described in an exact manner in the present shell element because this element is based on geometrically exact surface representation. The displacement field of the proposed finite element includes slope of deflection, which requires continuity between element interfaces. Thus the nonconforming shape function of Specht's three-node triangular plate bending element is employed to interpolate out-of-plane displacement. The present element passes the bending and twisting patch tests in flat surface configurations. The developed element is evaluated through the eigenvalue problems of composite cylindrical shells with multiple delaminations. Through the numerical examples it is demonstrated that the proposed shell element is efficient because it has minimal degrees of freedom per node. The present shell element should serve as a powerful tool in the prediction of natural frequency and modes of multi-layered thick laminated shell structures with arbitrary-shaped multiple delaminations.

• 한국강구조학회 논문집
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• 제23권4호
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• pp.455-464
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• 2011

본 논문에서는 곡선 보강 복부판의 좌굴해석을 대체전단변형률 장을 갖는 8, 9절점 평면 쉘요소를 이용한 유한요소해석을 통하여 수행하였다. 수평보강재 및 수직보강재를 갖는 경우의 수직면내 곡선 복부판의 좌굴거동을 조사하기 위해 면내 모멘트 하중을 받는 경우에 대해서 복부판의 폭(b)의 변화, 보강재와 복부판의 휨-강성비(${\gamma}=EI/bD$)의 변화에 대한 변수연구를 수행하였다. 보강재를 갖지 않는 경우의 수직면내 곡선 복부판의 정적거동에 대해서도 조사되었다. 또한 모멘트 하중을 받는 경우에서 수평 보강재 및 수직 보강재의 좌굴능력이 비교 되었다.