• 대한기계학회논문집A
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• 제25권4호
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• pp.582-591
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• 2001

It is known that the reduced integration, modified shape function, anisoparametric and non-conforming element can reduce the error induced by stiffness locking phenomenon in the finite element analysis. In this study, we propose new anisoparametric curved beam element. The new element based on reduced minimization theory is composed of different shape functions in each displacement field. By the substitution of this modified shape function, the unmatched coefficient that cause stiffness locking in the constraint energy is eliminated. To confirm the availability of this new model, we performed numerical tests for a simple model. As a result of numerical test, the undulate stress patterns are disappeared in static analysis, and displacements and stresses are close to exact solution. Not only in the static analysis but also in the eigen analysis of free vibrated curved beam model, this element shows successful convergent results.

• 한국전산구조공학회논문집
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• 제14권3호
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• pp.349-359
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• 2001

본 논분은 평판구조물의 동적 시간이력해석을 수행하기 위하여 개발된 사절점 판요소에 대하여 기술하였다. 이 요소는 두꺼운 판에서 발생하는 횡전단 변형효과를 고려하기 위하여 Reissner-Mindlin(RM)가정을 도달하였다. 알려진 바와 같이 RM가정을 바탕으로 개발된 판요소가 얇은 판에 적용되면 전단강성 과대현상(,Shear Locking Phenomenon)을 일으키는데 이를 개선하기 위하여 본 연구에서는 가변형도법을 이용한 대체변형도를 자연좌표계에 준하여 명시적으로 유도하였다. 개발된 저차 판요소는 중앙 차분법을 이용한 명시적인 동적 해석 알고리즘에 적용되었으며 이때 판의 대각질량행렬은 특별집중질량법을 사용하여 형성하였다. 개발된 판의 성능은 수치예제를 통하여 평가하고 검증하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.367-371
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• 2001

In the shape optimization based on the finite element method, the accuracy of finite element analysis of a given structure is important to determine the final shape. In case of a bending dominant problem, finite element solutions by the full integration scheme are not reliable because of the locking phenomenon. Furthermore, in the process of shape optimization, the mesh distortion is large due to the change of the structure outline: therefore, we cannot guarantee the accurate result unless the finite element itself is accurate. We approach to more accurate shape optimization to diminish these inaccuracies by improving the existing finite element. The shape optimization using the modified finite element is applied to a two-dimensional simple beam. Results show that the modified finite element have improved the optimization results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.405-410
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• 2000

Generally, it is known that the reduced integration, modified shape function anisoparametric and non-conforming element can minimize the error induced by stiffness locking phenomenon in the finite element analysis. In this study, new anisoparametric curved beam elements are introduced by using different shape functions in each displacement field. When these shape functions are substitute for functional, we can expect that the undulate stress patterns are not appeared or minimized because there is no unmatched coefficient in the constrained energy equation. As a result of numerical test, the undulate stress patterns are disappeared, and displacement and stress are coincide with the exact solutions.

• 대한기계학회논문집
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• 제17권11호
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• pp.2694-2703
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• 1993

In the vibration analysis of Timoshenko beams by the finite element method, it is necessary to use a large number of elements or higher-order elements in modeling thin beams. This is because the overestimated stiffness matrix due to the shear locking phenomenon when lower-order displacement-based elements are used yields poor eigensolutions. As a result, the total number of degrees of freedom becomes critical in view of computational efficiency. In this paper, the curvature-based formulation is applied to the vibration problem. It is shown that the curvaturebased beam elements are free of shear locking and very efficient in the vibration analysis.

• Steel and Composite Structures
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• 제47권3호
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• pp.365-374
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• 2023

This paper presents a new scheme for constructing locking-free finite elements in thick and thin plates, called Discrete Shear Gap element (DSG), using multiphase material topology optimization for triangular elements of Reissner-Mindlin plates. Besides, common methods are also presented in this article, such as quadrilateral element (Q4) and reduced integration method. Moreover, when the plate gets too thin, the transverse shear-locking problem arises. To avoid that phenomenon, the stabilized discrete shear gap technique is utilized in the DSG3 system stiffness matrix formulation. The accuracy and efficiency of DSG are demonstrated by the numerical examples, and many superior properties are presented, such as being a strong competitor to the common kind of Q4 elements in the static topology optimization and its computed results are confirmed against those derived from the three-node triangular element, and other existing solutions.

• 한국컴퓨터정보학회지
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• 제1권2호
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• pp.95-107
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• 1995

동시성 제어 기업은 트랜잭션 처리 시스템의 성능에 중요한 영향을 미친다. 전통적인 록킹 기법은 대기 트랜잭션이 로크를 가지고 있으면서 진행중인 다른 트랜잭션을 블록시키는 블록킹 현상을 일으킨다. 제안된 방법은 트랜잭션 실행의 다음 단계에서 그들의 블록킹 형태를 지연함에 의해서 블록킹 확률을 감소시킨다. 트랜잭션 실행은 전통적인 록킹같은 블록킹 상태와 트랜잭션이 로크를 기다리지만 다른 트랜잭션은 블록화하지 않는 비블록킹 상태로 나누어 볼 수 있다. 그러나 비블록킹 상태 중에 처리된 데이터는 트랜잭션을 취소 시킬 수 있다. 블록킹과 취소 효과를 적절히 균형을 이루어서 제안된 방식은 모든 데이터 함유와 자원 함유 수준에서 전통적 록킹과 OCC방식보다 더 뛰어난 성능을 가지고 있다.

• Architectural research
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• 제18권3호
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• pp.113-120
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• 2016

The stability and resistance of the plates under in-plane loading is crucial in the design of structures. For the assessment of structural stability, it is necessarily required to have accurate finite element technologies. Therefore, the enhanced 9-node plate (Q9-ANS) element is introduced for the linear buckling analysis of plate where the critical buckling load has to be determined. The Q9-ANS is developed with the Reissner-Mindlin (RM) assumptions which consider transverse shear deformation of the plate. Assumed shear strain is used to alleviate the shear locking phenomenon. Numerical examples are carried out to verify the performance of the Q9-ANS element in calculation of critical buckling load of the plates.

• 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.

• Steel and Composite Structures
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• 제48권5호
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• pp.583-597
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• 2023

This paper introduces a novel approach to multi-material topology optimization (MTO) targeting in-plane bi-directional functionally graded (IBFG) non-uniform thickness Reissner-Mindlin plates, employing an alternative active phase approach. The mathematical formulation integrates a first shear deformation theory (FSDT) to address compliance minimization as the objective function. Through an alternating active-phase algorithm in conjunction with the block Gauss-Seidel method, the study transforms a multi-phase topology optimization challenge with multi-volume fraction constraints into multiple binary phase sub-problems, each with a single volume fraction constraint. The investigation focuses on IBFG materials that incorporate adequate local bulk and shear moduli to enhance the precision of material interactions. Furthermore, the well-established mixed interpolation of tensorial components 4-node elements (MITC4) is harnessed to tackle shear-locking issues inherent in thin plate models. The study meticulously presents detailed mathematical formulations for IBFG plates in the MTO framework, underscored by numerous numerical examples demonstrating the method's efficiency and reliability.