• 소음진동
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• 제6권4호
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• pp.457-467
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• 1996

The analytical solutions for the free vibration and buckling of cross -ply laminated composite cylindrical shell with the orthogonal stiffeners, i. e., axial stiffeners(stringers) and circumferential stiffeners(rings), are presented using the energy method. The stiffeners are assumed to be an integral part of the shell and have been directly included in analysis(it's called discrete stiffener theory). The effect of the parameters such as the stacking sequences, the shell thickness, the shell length-to-radius ratio are studied. By comparison with the previously published analytical results for the stiffened cylindrical shells, it is shown that natural frequencies can be determined with adequate accuracy.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.349-354
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• 1996

The analytical solutions for the free vibration and buckling of cross-ply laminated composite cylindrical shell with axial stiffeners(stringers) and circumferential stiffeners(rings), that is, orthogonally stiffened shells, are presented using the energy method. The stiffeners are assumed to be an integral part of the shell and have been directly included in analysis(it's called discrete stiffener theory). The effect of the parameters such as the stacking sequences, the shell thickness, the shell length-to-radius ratio are studied. By comparison with the previously published analytical results for the stiffened cylindrical shells, it is shown that natural frequencies can be determined with adequate accuracy.

• 한국산학기술학회논문지
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• 제20권10호
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• pp.7-17
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• 2019

대형 해상 구조물 시공이 증가됨에 따라 석션 가물막이 또한 대형화되고 있고, 이로 인해 가물막이 상판의 휨 변형을 효과적으로 억제하기 위한 상판 보강 설계가 가물막이 설계의 핵심적인 요소가 된다. 본 연구는 석션 가물막이 상판의 보강으로 인한 구조 거동 변화를 유한요소모델을 이용해 분석하고, 효과적인 상판 보강 배치 방안 도출을 위한 통찰을 제공하고자 한다. 기존 석션 앵커를 조사하여 각형 석션 가물막이 상판의 여러 보강 유형을 결정하였으며, 각 보강 상판을 분석하였다. 보강 상판의 응력과 변형을 비교하여 구조성능을 평가하였고, 추가로 상판 가장자리의 반력 분포를 분석함으로써 보강재 배치가 상판-케이슨 벽체 연결부에 미치는 영향을 함께 조사하였다. 유한요소해석 결과로부터, 방사방향 보강재가 상판의 처짐 및 응력 감소에 크게 기여한 반면, 상판-벽체 연결부의 수평 전단력을 집중 및 증가시켜 연결부 설계에 불리하게 작용함을 확인할 수 있었다. 또한, 내/외측 환형 보강재는 자체 보강 효과가 미미하나, 부분적으로 배치된 방사 보강재와 함께 연결해 배치되면 응력 및 처짐 개선에 기여함을 알 수 있었다.

• Steel and Composite Structures
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• 제19권1호
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• pp.75-92
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• 2015

In this paper, optimization of cylindrical shells under external pressure to minimize its weight has been studied. Buckling equations are based on standard of ABS underwater vehicles. Dimension and type of circumferential stiffeners, and its distance from each other are assumed as variables of optimization problem. Considering the extent of these variables, genetic algorithms have been used for optimization. To study the effect of hydrostatic pressure on the shell and its fabrication according to the existing standards, geometrical and construction as well as stress and buckling constraints have been used in optimization algorithm and also penalty functions are applied to eliminate weak model. Finally, the best model which has the minimum weight considering the applied pressure has been presented.

• 대한기계학회논문집A
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• 제20권9호
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• pp.2875-2886
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• 1996

This work present the experimental resutls for the free vibration of unstiffened, stiffened cylindrical shell filled with air, half water and full water. The natural frequencies and mode shapes of unstiffened, stiffened cylindrical shell are obtained experimentally also. The natural frequencies of stiffened cylindrical shell were generally highter than those of unstiffened cylindrical shell and natural requencies were decreased as cylindrical shell was filled with water. The effect of circumferential stiffener in the first mode was shown that natural frequency more increased 25% at air environment, 29% at half water environment and 37% at full water than those of unstiffened cylindrical shell, respectively. Also, the natural frequencies were decreased according to the added mass effect of fluid in the shell of unstiffened and stiffened cylindrical shell. The six mode shape results of all cases are simular and given. The natural frequencies are determined for a wide range of parameters : e.g. unstiffened shell, and filled with air, half and full water. The effects of varying the parameters on the free vibration frequencies and mode shapes are discussed.