• 한국공간구조학회지
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• 제3권4호
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• pp.11-17
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• 2003

• Structural Engineering and Mechanics
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• 제73권1호
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• pp.1-16
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• 2020

Finite elements based on the partition of unity (PU) approximation have powerful capabilities for p-adaptivity and solutions with high smoothness without remeshing of the domain. Recently, the PU approximation was successfully applied to the three-node shell finite element, properly eliminating transverse shear locking and showing excellent convergence properties and solution accuracy. However, the enrichment with the PU approximation results in a significant increase in the number of degrees of freedom; therefore, it requires greater computational cost, thus making it less suitable for practical engineering. To circumvent this disadvantage, we propose a new strategy to decrease the total number of degrees of freedom in the existing PU-based shell element, without loss of optimal convergence and accuracy. To alleviate the locking phenomenon, we use the method of mixed interpolation of tensorial components and perform convergence studies to show the accuracy and capability of the proposed shell element. The excellent performances of the new shell elements are illustrated in three benchmark problems.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.55-61
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• 2002

In the present study, a first order shear deformable Loop-subdivision triangular element which can handle transverse shear deformation of moderately thick shell and composite laminated or sandwich shells are developed. The developed element is more general than the previous one based on classical shell theory, since it includes the effect of transverse shell deformation and has standard five degrees of freedom per node. The quartic box spline function is employed as the interpolation basis function. Numerical examples for the benchmark static shell problems are analyzed to assess the performance of the developed subdivision shell element and locking trouble.

• Steel and Composite Structures
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• 제28권3호
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• pp.389-401
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• 2018

An isoparametric six-node triangular element is utilized for geometrically nonlinear analysis of functionally graded (FG) shells. To overcome the shear and membrane locking, the element is improved by using strain interpolation functions. The Total Lagrangian formulation is employed to include the large displacements and rotations. Finding the nonlinear behavior of FG shells via laminated modeling is also the goal. A power function is employed to formulate the variation of elastic modulus through the thickness of shells. The results are presented in two ways, including the general FGM formulation and the laminated modeling. The equilibrium path is obtained by using the Generalized Displacement Control Method. Some popular benchmarks, including hyperbolical shell structures are solved to declare the correctness and accuracy of proposed formulations.

• 한국전산구조공학회논문집
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• 제17권2호
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• pp.151-160
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• 2004

본 연구에서는 서브디비전 방법 중 루프 서브디비전 방법을 이용하여 초기의 데이터 값으로부터 몇 번의 서브디비전 과정을 거쳤을 때, 초기 데이터 점이 극한곡면 위에 있도록 곡면 재생성 방법을 구현하였으며, n번 서브디비전을 수행한 곡면의 정확도를 곡률과 좌표값의 상대오차로 평가하였다. 또한 절의 전반변형을 표현할 수 있는 일차 전단변형 루프 서브디비전 유한요소를 개발하였다. 새롭게 개발된 요소는 한 개의 절점에서 6개의 자유도를 가지고 전반 변형효과를 포함하는 일반화된 요소인데, 기저함수로 4차 박스-스플라인함수가 사용되었다. 평가 수치예제를 통해 서브디비전 꿸 요소의 성능을 평가/검증하였다. 본 연구에서 개발된 서브디비전 요소는 다중해상도 해석과 기하학적 모델링에 널리 사용될 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.745-750
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• 2000

A warpage analysis program has been developed for fiber-reinforced injection molded parts. The warpage is Predicted from the residual stress and anisotropic thermo-mechanical properties coupled with fiber orientation in the integrated injection molding simulation. A simple elastic model is used for the calculation of thermally and pressure-induced residual stresses which are employed as the initial conditions in the structural analysis. To improve the reliability of warpage analysis, a new triangular flat shell element superimposing well-known efficient plate bending and membrane element is presented. The numerical examples address the neccesity to use anisotropic models for fiber-reinforced materials and show that predicted warpage is in good agreement with experimentally measured one.

• 한국공간구조학회지
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• 제2권1호
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• pp.1-7
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• 2002

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.402-407
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• 2008

We suggest a linear elastic flat shell element based on the HT(hybrid Trefftz) method. We formulate the membrane part of the proposed element as an HT plane element with the drilling DOF. For the bending part, we developed a thick HT plate element that can represent transverse shear deformations accurately. Because we derive both the membrane and the bending parts consistently using the HT functional, we can easily construct the triangular and the quadrilateral elements in a unified way. In addition, warping of quadrilateral element is compensated by force and moment equilibrium equations. We evaluate the performance of the new element in terms of accuracy and convergence.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.865-870
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• 2004

This paper describes the generation of chordal surface for various shell structures, such as automobile bodies, plastic injection mold components and shell metal parts. After one-layered tetrahedral mesh is generated by an advancing front algorithm, the chordal surface is generated by cutting a tetrahedral element. It is generated one or two elements at a tetrahedral element and the chordal surface is composed with triangular or quadrilateral elements. This algorithm has been tested on several models with rib structure.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권2호
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• pp.144-149
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• 2006

This paper describes a novel automated analysis system for bellows of piping system. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy theory and computational geometry technique, is incorporated into the system, together with one of commercial FE analysis codes and one of commercial solid modelers. In this system, a geometric model, i.e. an analysis model, is first defined using a commercial solid modelers for 3-D shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay triangulation technique is introduced as a basic tool for element generation. The triangular elements are converted to quadrilateral elements. Practical performances of the present system are demonstrated through several analysis for bellows of piping system.