• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.187-194
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• 2012

The strength of particle-reinforced metal matrix composites is, in general, known to be increased by the geometrically necessary dislocations punched around a particle that form during cooling after consolidation because of coefficient of thermal expansion (CTE) mismatch between the particle and the matrix. An additional strength increase may also be observed, since another type of geometrically necessary dislocation can be formed during extensive deformation as a result of the strain gradient plasticity due to the elastic-plastic mismatch between the particle and the matrix. In this paper, the magnitudes of these two types of dislocations are calculated based on the dislocation plasticity. The dislocations are then converted to the respective strengths and allocated hierarchically to the matrix around the particle in the axisymmetric finite-element unit cell model. The proposed method is shown to be very effective by performing finite-element strength analysis of $SiC_p$/Al2124-T4 composites that included ductile failure in the matrix and particlematrix decohesion. The predicted results for different particle sizes and volume fractions show that the length scale effect of the particle size obviously affects the strength and failure behavior of the particle-reinforced metal matrix composites.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.1-10
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• 2004

Adaptive finite element analysis, in which its solution error meets with the user defined allowable error, is recently used to improve the reliability of finite element analysis results. This adaptive analysis is composed of two procedures; one is the error estimation of an analysis result and the other is the reconstruction of finite elements. In the (p-method, an element size is controlled by relocating of nodal positions (r-method) and the order of an element shape function is determined by the hierarchical polynomial (p-method) corresponding to the clement solution error by the enhanced SPR. In order to show the effectiveness and the accuracy of the suggested rp-method, various numerical examples were analyzed and these analysis results were examined by comparing with those obtained by the existed methods.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.123-130
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• 1996

탄소성파괴역학의 발달과 함께 원자력 발전소의 설계시 고려해야 하는 고에너지 배관의 양단파단사고와 같은 극한 가정 대신 파단전누설(LBB : Leak Before Break)개념을 배관설계시 고려할 수 있도록 관련 규제 요건이 완화되어 원자력 발전소 고에너지 계통 설계에 새로운 설계 개념으로 적용할 수 있게 되었다. 파단전누설개념 적용시 균열 안정성 평가에 가장 널리 사용되는 방법은 J-T 방법이다. 본 연구에서는 유한요소법 사용시 균열 선단에서 요소의 크기 및 경계 조건 (Boundary Condition)이 변화할 때 Applied J 적분값에 미치는 영향을 ABAQUS 전산 프로그램을 이용하여 조사하였다.

• IE interfaces
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• v.8 no.3
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• pp.171-185
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• 1995

유한 요소 시스템 행렬의 프로파일을 줄일 수 있는 새로운 절점 번호 자동부여 알고리즘을 개발하였다. 이 알고리즘은 절점 연결 행렬 압축 기법과 웨이브 프론팅 개념에 의한 번호 부여 기법을 복합한 방법으로 알고리즘이 간단, 명료하다. 대표적인 유한 요소 모델을 선정하여 본 알고리즘과 기존 알고리즘을 비교하였다. 새로운 알고리즘의 번호 부여 시간은 기존의 우수한 알고리즘과 비슷하였으나 프로파일 크기는 작았다.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.1
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• pp.1-7
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• 2012

This study investigates free vibration characteristics of laminated composite structures with different embedded delamination sizes and locations using the solid element. The three-dimensional finite element (FE) delamination model described in this paper, in comparison with the conventional approaches, is more attractive not only because it shows better accuracy but also it shows the entire mode shape. The FE model using ABAQUS is used for studying free vibrations of laminates containing an various embedded delamination. The numerical results obtained are in good agreement with those reported by other investigators. In particular, new results reported in this paper are focused on the significant effects of the local vibration mode for various parameters, such as size of delamination, aspect ratio, and location of delamination.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.58-58
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• 2004

현재 금속 성형공정에 대한 해석법으로 강소성 유한요소법이 널리 이용되고 있다. 강소성 유한요소법에서는 주어진 시간에서 속도장을 얻고 가공물 형상을 시간증분 만큼 갱신하는 과정을 반복하여 비정상상태 금속성형공정의 해석한다. 일반적인 강소성 유한요소법은 형상갱신(Geometry update) 과정에서 오일러법(Euler method)을 이용한다. 오일러법에서는 시간증분의 크기가 해의 정밀도에 중요한 인자이다. 충분히 정밀한 해를 얻기 위해, 작은 시간증분을 이용하여 비정상상태 금속성형공정을 해석함으로써 해석시간이 많이 걸리는 단점이 있으며 형상갱신에 따른 가공물 체적손실(Volume loss)이 발생한다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.19-19
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• 2003

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2002.08a
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• pp.298-301
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• 2002

경계요소법은 Laplace 방정식을 지배방정식으로 하는 지하수 흐름이나 해안공학 문제의 해석에 있어 매우 정확한 해를 제공하는 수치 기법이다. 특히, 경계요소법은 유한차분법이나 유한요소법과 같은 다른 수치기법과 달리 계산시간이나 기억용량의 절감 등에서 매우 효율적이다. 또한, 임의의 형태를 갖는 지형에도 큰 문제없이 쉽게 적용할 수 있고 요소의 크기를 자유롭게 조절할 수 있는 장점이 있다. (중략)

• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.343-349
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• 2014

The dental osseointegration implant should be enough to endure occlusion load and it's required to have efficient design and use of implant to disperse the stress into bones properly. Solidworks as a finite element analysis program for modeling and analysis of stress distribution was used for the research. The simple crown model was designed on applying conjoined condition with tightening torque of 20 Ncm of a abutment screw between a cement retained implant abutment and a fixture. A $45^{\circ}$ oblique loading from lingual to buccal side on buccal cusps of crown and performed finite element analysis by 100 N of external load. The results by a analysis for stress distribution of supporting bones of fixture were as below. The von Mises stress was concentrated on the upper side of supporting compact bone regardless of the diameters and lengths of fixture, and the efficiency result of stress reduction was increase of fixture's diameter than it's length. Therefore, it's effective to use wider fixture as possible to the conditions of supporting jaw bone.

• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.159-165
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• 2003

A tubular member with through-gusset plate is often used to transmit axial compression in an electric transmission towers. In current code, the strength of tubular member is evaluated with an effective length factor k=0.9 without considering the deformation of boundary element. A buckling strength of member with end gusset plate is affected by stiffness ratio($\beta$) and the length ratio(G) between main tubular member and end gusset plate. In this study theoretical mechanism based on the elastic buckling behavior was investigated, and finite element analysis was performed to propose a formula for the buckling strength and effective length factor of tubular member in elsatic and inelastic ranges.