• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.491-498
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• 2016

Stress on plates may increase in the neighborhood the edges or the holes for rivets or bolts. Excessive stress concentration may lead to severe breakage of the plates. Thus, it is important to conduct optimization of arrangement of holes at the design stage. In this paper, accuracy of FEM analysis was examined for such stress concentration. By changing the hole size on a narrow plate, change of the stress concentration factor(K) was investigated. Additionally, the same experiment was conducted about series of multiple holes on plate to investigate interaction between the adjacent holes. Then, the FEM results were compared to the reference predictions respectively. Finally, a method by which simple stress concentrating situations can be optimized, will be suggested. This method was examined by FEM, and showed similar tendency with the expectation. Therefore, this method can be valuable when arranging the holes on a plate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.2
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• pp.92-100
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• 2016

Reliability analysis of tripod support structure for offshore wind turbine was performed. Extreme distribution function of peak response due to wind and wave loads was estimated by applying peak over threshold(POT) method. Then, stress based limit state function was defined by using maximum stress of support structure which was obtained by multiplying beam stress and concentration factor. The reliability analysis result was compared when maximum stress was calculated from shell element. Reliability index was evaluated using first order reliability method(FORM).

• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.59-72
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• 1990

본 논문은 해양 구조물에 대한 확률적 기법을 이용한 스펙트럴 피로해석 방법에 대하여 기술하고 있다. 환경조건 특히 파도 및 관련된 해상상태, 파도 스펙트럼에 대하여 조사하였다. 각종 공식을 이용한 응력 집중계수와 유한요소법을 이용한 응력 집중계수 산출 방법 및 피로수명에 대한 그 영향에 대하여 연구하고, S-N선도의 선택과 해상상태의 간략화 문제등에 관해서도 다루었다. 마지막으로 스펙트럴 피로해석 기법을 응용한 실제 피로해석 사례 연구를 통하여 본 방법의 유용성을 입증하였다.

• Computational Structural Engineering
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• v.10 no.3
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• pp.7-14
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• 1997

본 고에서는 설계자가 초기 설계시 적용할 수 있는 간이피로해석방법에 대하여 기술하였으며, 특히 선체의 각 구조상세에 대하여 산정된 응력집중계수를 이용하여 피로수명을 쉽게 평가할 수 있는 집중응력방법을 정립하였다. 이 집중응력방법을 사용하면 모든 구조상세에 대하여 한개의 S-N 선도를 적용하게 되므로 일관성 있는 피로상도해석을 수행할 수 있다. 또한 피로수명에 큰 영향을 미치는 파랑하중은 설계조건에 주어진 선급규칙에 따라 계산되어진다. 선체구조의 피로강도평가 기술은 계측, 실험, 해석 및 경험을 포함하는 광범위하고 포괄적이면서 정밀함을 요구하는 종합기술이지만 여기에는 많은 불확실성이 내포되어 있다. 따라서 이를 구명하고 모든 선체구조에 적용할 수 있는 신뢰성 있는 피로강도 평가기술을 개발하기 위하여는 실선계측을 통한 피로하중규명 선체구조에 적용할 수 있는 피로강도 Data base개발, 균열진전해석 등 많은 과제에 대한 집중적인 연구가 계속 수행되어야 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1163-1169
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• 2014

In this study, a fatigue assessment method for vehicle suspension systems having welded geometries was established under a bending loading condition. For the fatigue life estimation of the actual product's welded joints made of different steels, bending fatigue tests were performed on welded specimens with a simplified shape for obtaining the moment-fatigue-life plot. Further, geometry modeling of the simplified welded specimens was conducted. Results of finite element analysis were used to obtain the stress-fatigue-life plot. The analysis results were also used to calculate the stress concentration factors for notch-factor-based fatigue life estimation. The test results were compared with results of the general notch-factor-based fatigue life estimation for improving fatigue assessment. As a result, it was concluded that both the welded fatigue tests and the notch-factor-based fatigue life estimation are necessary for accurate fatigue assessment.

• Computational Structural Engineering
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• v.4 no.2
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• pp.77-85
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• 1991

A new finite element technology based on the p-version of E.F.M. is discussed with reference to its potential for application to stress intensity factor computations in linear elastic fracture mechanics, especially cracked cylindrical shells. It is shown that the p-version model is far better suited for computing the stress intensity factors than the conventional h-version models with the help of three test problems. The main advantage of this technology is that the accuracy of approximation can be established without mesh refinement or the use of special procedures such as crack-tip element and mixed variational approach.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.1
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• pp.27-32
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• 1987

제2장에서 선형타성체에 대한 파괴역학의 일반적인 개념을 약술하였다. 즉 응력확대계수(K) 와 응력집중계수($1_{4}$)의 차이, 에너지 해방율(1$\sub$y)및 $_{4}$와 K의 관계를 이론적으로 살펴보았다. 물론 식(2-35) 및 (2-36) 등은 균열전파 경로가 직선이 아닌 경우에 적용한다는 것은 무리가 있으나 전체적인 이해를 돕기위해서 앞에서와 같이 기술하였다. 세가지 경우의 응력확대 계수 $_{4}$, $_{4}$및 $_{4}$는 하중과 균열의 크기 및 시편의 크기 또는 균열이나 결함을 포함 하고 있는 기계요소 및 구조물의 기하학적인 형상에 관련이 되어져서 결정이 된다.

• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.209-209
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• 1990

• Proceedings of the KWS Conference
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• 1990.11a
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• pp.124-127
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• 1990

• Journal of the Korea Convergence Society
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• v.5 no.1
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• pp.23-27
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• 2014

In case eccentric load is applied at compact tension specimen, the propagation behavior due to existence or nonexistence of hole, numbers and positions of holes near crack is investigated in this study. Strain energy, displacement and stress happened in specimen are examined through simulation analysis. And stress intensity factor is obtained by the basis of strain energy and deformation. When defect or hole exists in structure, the possibility of fracture can be thought to be verified by using the study result.