• Journal of Ocean Engineering and Technology
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• v.2 no.1
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• pp.83-89
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• 1988

정지된 유동장에 놓인 반무한 평판이 횡방향으로 갑자기 출발하는 경우에 있어서 평판의 끝에서 발생하는 보텍스의 거동을 해석적 및 수치적 측면에서 검토하였다. 해석적 방법은 단일 보텍스 모델에 근거를 두었으며, 해석결과 순환량은 시간의 1/3승, 보텍스의 중심까지의 거리는 시간의 2/3승에 비례하여 증가함을 알 수 있었다. 룬게.쿠타(Runge-Kutta)방법을 써서 분리 보텍스 모델에 따른 비선형 운동방정식의 해를 수치적으로 구했다. 수치해는 시간의 경과에 따라 해석 해에 접근하였다. 보텍스의 형상에 있어서도 실험결과와 잘 맞았다.

• Journal of Ocean Engineering and Technology
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• v.4 no.1
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• pp.110-119
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• 1990

This study is concerned about the stress concentration factor measurement by photoelastic method, for the case of two circular holes arrangement in 3mm semi-infinite plate under tensile load, the ratio of those two circular holes diameter, the ratio of distance apart from circular holes to breadth and the two holes arrangement angle with loading direction were varied. Besides, the measured stress concentration by photoelastic method around one circular hole was compared with that by strain-gage method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.3
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• pp.433-440
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• 2002

A branched crack in a semi-infinite plate under uniform tension and bending moment is considered in this study By using the superposition, the stress and moment intensity factors for the branched crack subjected to uniform tension and bending moment we evaluated. The stress intensity factors we obtained by using the finite element method and the J-based mutual integral. The moment intensity factors are calculated by extrapolating the values of the moment new the crack tip. Numerical results lot the normalized stress and moment Intensity factors we shown as functions of the ratio of branched crack length to main crack length and the branching angle.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.2
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• pp.257-264
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• 1986

무한평판에 묻혀진 크랙에 대한 응력확대계수를 결정하는 전위분포법을 반무한 평판에서의 표면크랙에 확장 적용하였다. 이를 위해 반평면에서의 전위응력의 기본 해가 간단한 복소수 응력함수형태로 얻어졌다. 평형을 이루는 절편적인 분포로부터 응력확대의 계수를 계산하는 새로운 방식을 제안하였으며, 수직표면 크랙과 묻혀진 경사크랙에 대한 기존해와 이 방법의 결과가 상호 비교되었다. 경사진 표면크랙에 대한 계산결과는 유한평판에서의 기존하는 Mapping Collocation 해석과 비교되어 좋은 일치를 보여 주었다. 구부러진 크랙과 대칭으로 가지친 크랙에 대해서는 표면크랙과 묻혀진 크랙사이에 상당한 차이가 있음이 나타났다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.3
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• pp.61-70
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• 1985

In this paper, the analysis of plates resting on Winkler's springs and on an isotropic elastic half space is made by the finite element method using an isoparametric element. A new technique is introduced to calculate the numerical values of influence area for the soil element. A computer program NMAT has been developed and checked through demonstrating examples.

• Journal of Energy Engineering
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• v.8 no.1
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• pp.181-188
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• 1999

재료의 표면을 pulsed laser로 가열할 때, 유한한 두께를 가지는 반무한 평판의 온도분포를 해석하여 열확산계수, 재료의 두께, 열원의 주기, 그리고 열원의 반경이 온도분포에 미치는 영향을 알아보았다. Pulsed laser에 의하여 가열되는 불투명 고체의 시간에 따른 온도는 전체적으로 증가하지만 열원의 주기와 동일한 주기를 가지고 일정한 온도차를 가지는 전체온도와 평균온도의 차, Tac가 존재한다. 열확산계수가 증가하면 재료 내부로 에너지의 확산이 활발하기 때문에 Tac는 커진다. 재료의 두께가 열확산길이보다 얇은 경우에는 두께변화에 따라서 온도가 민감하게 변하지만, 열확산길이보다 재료의 두께가 두꺼울 때는 두께의 변화에 관계없이 거의 일정한 온도가 나타난다. 열원의 단속주파수가 증가하면 한 주기당 에너지가 작아지므로 Tac의 크기는 작아진다. 열원의 반경이 커지면 단위면적당 에너지가 감소하므로 Tac의 크기는 삼각파, 싸인파, 사각파 순으로 크게 나타난다. 따라서 열원의 파형을 측정하여 이를 적용하는 것이 바람직하다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.73-79
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• 1997

It is one of classical problems in the elastic theory to analyze contact stresses between elastic bodies. Concrete pavements under traffic wheel loads can be considered as one of these typical Problems. In the paper, Mindlin plate theory is used to consider the transverse shear effect, 8-node isoparametric plate bending element is adopted in this study, and an elastic plate resting on tensionless elastic half-space is analyzed by finite element method. The Boussineq's solution of elastic half-space is used to evaluate the flexibility of foundation. To obtain the boundary of contact area, the flexibility matrix of foundation is modified after each cycle of analysis iteratively. A Numerical example is presented by using these method.

• Journal of the Korean Society for Railway
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• v.18 no.1
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• pp.53-62
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• 2015

LWDT was developed for use as an alternative technique to measure the stiffness of trackbed soils. In this study, numerical and theoretical analyses of LWDT's acting mechanism were performed. The effectiveness of the adapted elastic formula used for calculation of the dynamic modulus, Evd, was investigated theoretically and also numerically by running ABAQUS analysis. The minimum thickness of the upper layer is proposed based on the analysis. Correction factors for the formula of elastic modulus are also proposed in this study. In the future, following field test results and laboratory mechanical tests such as the resonant column test, a guideline for the use of LWDT as a standard test protocol in track construction sites, as a measuring tool for the degree of compaction and/or stiffness and dynamic modulus, will be proposed based on this analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.1-8
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• 1992

A method analizing contact pressure between plate and elastic half space is presented by using F.E.M. With the method, the pressure intensities at surface nodes of half space cae be directly calculated by using flexibility matrix of half space. The method is originally presented by Y.K. Cheung et al.(3) Insted of Y.K. Cheung's method, which use a conception of equi-contact pressure area around each surface nodes of half space in the noded rectanqular element area. We use the equi-contact pressure area around the Gaussian integration points of half space surface in the noded isoparametric element area. Numarical examples are presented and compared with other's studies.

• Tribology and Lubricants
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• v.38 no.3
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• pp.73-83
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• 2022

This paper is concerned with an analysis of a surface edge crack emanated from a sharp contact edge. For a geometrical model, a square wedge is in contact with a half plane whose materials are identical, and a surface perpendicular crack initiated from the contact edge exists in the half plane. To analyze this crack problem, it is necessary to evaluate the stress field on the crack line which are induced by the contact tractions and pseudo-dislocations that simulate the crack, using the Bueckner principle. In this Part I, the stress filed in the half plane due to the contact is re-summarized using an asymptotic analysis method, which has been published before by the author. Further focus is given to the stress field in the half plane due to a pseudo-edge dislocation, which will provide a stress solution due to a crack (i.e. a continuous distribution of edge dislocations) later, using the Burgers vector. Essential result of the present work is the corrective functions which modify the stress field of an infinite domain to apply for the present one which has free surfaces, and thus the infiniteness is no longer preserved. Numerical methods and coordinate normalization are used, which was developed for an edge crack problem, using the Gauss-Jacobi integration formula. The convergence of the corrective functions are investigated here. Features of the corrective functions and their application to a crack problem will be given in Part II.