• 한국강구조학회 논문집
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• 제30권1호
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• pp.25-35
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• 2018

균일 외압을 받는 링 보강 원형단면 강재 쉘에 대하여 재료 및 기하학적 비선형 유한요소법(GMNIA)을 적용하여 외압강도를 평가하였다. 링 보강 쉘의 기하학적 초기결함의 진폭, 반경 대 두께 비, 링 보강재 간격 대 반경비 등이 외압강도에 미치는 영향을 분석하였으며, Eurocode 3과 DNV 설계기준에 의한 설계 외압 강도와 유한 요소해석으로 구한 외압강도를 비교 평가하였다. 기하학적 초기결함의 형상은 선형탄성 좌굴해석에 의한 좌굴모드를 적용하였으며 보강 쉘의 반경 대 두께 비는 250~500범위를 고려하였다.

• 한국소음진동공학회논문집
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• 제25권1호
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• pp.33-39
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• 2015

This paper investigates the underwater acoustic radiation from a periodically stiffened cylindrical shell excited resiliently mounted machinery. Underwater acoustic radiation is important to a submarine. Generally, submarine structure can be modeled as stiffened cylindrical shell immersed in water. Analytical model is derived for the far-field acoustic radiation from machinery installed inside cylindrical shell. The analytical model includes the effect of fluid loading and interactions between periodic ring stiffeners. Transmitted force from machine to a shell through isolator can be different by the impedance of shell. In this paper the effect of a shell impedance for acoustic radiation is investigated. Impedance of a shell should be considered if thickness of a shell is thin.

• 대한기계학회논문집A
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• 제23권11호
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• pp.2040-2049
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• 1999

The Rayleigh-Ritz method is used to investigate the natural frequencies and mode shapes of the ring stiffened cylindrical shells with a rectangular cutout. The cutout is located on the center of the shell. The Love's thin shell theory combined with the discrete stiffener theory is adopted to formulate the analytical model of the shell. The effect of stiffener eccentricity, number, and position on vibration characteristics of the shell is examined. Also the effect of cutout size is examined. By comparison with previously published analytical and new FEM results, it is shown that natural frequencies and mode shapes can be determined with adequate accuracy.

• Smart Structures and Systems
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• 제25권6호
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• pp.643-655
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• 2020

Active control of nonlinear vibration of stiffened functionally graded (SFG) cylindrical shell is studied in this paper. The system is subjected to axial and transverse periodic loads in the presence of thermal uncertainty. The material composition is considered to be continuously graded in the thickness direction, also these properties depend on temperature. The relations of strain-displacement are derived based on the classical shell theory and the von Kármán equations. For modeling the stiffeners on the cylindrical shell surface, the smeared stiffener technique is used. The Galerkin method is used to discretize the partial differential equations of motion. Some comparisons are made to validate the SFG model. For suppression of the nonlinear vibration, the linear and nonlinear control strategies are applied. For control objectives, the piezoelectric actuator is attached to the external surface of the shell and the thin ring piezoelectric sensor is attached to the middle internal surface of shell. The effect of PID, feedback linearization and sliding mode control on the suppression of vibration for SFG cylindrical shell is presented.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.631-636
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• 2008

The cylindrical shells are mainly used in the nuclear energy structure, pressure vessel, boiler and so on. When designing of shell structures, predicting the structure change under variety boundary conditions are necessary for estimating the safety. Design variables for the design engineer include multiple material systems and boundary conditions, in addition to overall structural design parameters. Since the vibration of stiffened cylindrical shell is an important consideration for structures design, the reliable prediction method and design methodology should be required. In this study, the optimum design of stiffened cylindrical shell for maximum natural frequency was studied by analytic and numerical method.

• 대한기계학회논문집A
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• 제36권3호
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• pp.305-311
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• 2012

보강 원통셸의 기본 고유 진동수를 최적화하기 위해서, 보강재의 개수를 1 개에서 5 개까지 보강된 원통셸에 대한 시뮬레이션을 수행하였다. 고유 진동수에 대한 최적화를 시뮬레이션하기 위해서 ANSYS 11.0 을 사용하였다. 최적화 방법으로 Subproblem Approximation Method 를 이용하였다. 최적화의 설계 함수로는 T-형 링 보강재의 기하형상이며, 제한 함수로는 보강에 따른 추가 부피가 10 % 이내로 제한하였다. 목적함수는 기본 고유진동수를 최대화하는 것이다. 최적 설계에 대한 성능 지표는 비보강 원통셸과 보강원통셸의 고유진동수와 부피의 비로서 정의하였다. 최적 성능 지수는 3 개의 보강재를 사용한 원통셸에서 나타났다.

• 소음진동
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• 제9권3호
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• pp.485-492
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• 1999

The effects of boundary conditions on vibration characteristics for the ring stiffered composite cylindrical shells are investigated by theoretical and experimental method. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect are adopted to derive the frequency equation. In experiment, the impact exciting method is used to obtain the vibraton results. Five different boundary conditions: clamped-clamped, simply supported-simply supported, free-free, clamped-free, clamped-simply supported are considered in this study.

• 한국강구조학회 논문집
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• 제26권3호
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• pp.219-229
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• 2014

원형 강관으로 보강된 GFRP 재질의 원통형 쉘구조에 대한 극한 휨 실험 및 범용 유한요소해석 프로그램인 ABAQUS를 사용한 전산해석을 수행하였다. 개인하수처리 시설의 설계 기준에서 제시된 직사각형 단면형상의 GFRP 재질의 보강링이 적용된 설계기준을 바탕으로 원형 강관 보강링에 대한 단면 재료 특성이 반영된 식을 검토하여 설계하였다. 보강링의 단면, GFRP 본체의 직경과 두께에 의한 극한 거동 특성을 분석하기 위하여 총 4개의 시험체를 설계 제작하여 집중하중 정적재하 시험을 수행하였다. 실험결과 강관 보강링이 사용된 GFRP 쉘구조는 휨파괴가 발생할 때까지 충분한 연성도를 가지고 있으며, 강관 보강링의 휨강성 증가에 따른 전체 구조물의 강도증진이 효과적임을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.359-364
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• 1998

The effects of boundary conditions on natural frequencies for the ring stiffened composite cylindrical shells are investigated by theoretical method. The Love's thin shell theory and the discrete stiffener theory with beam functions in the Ritz procedure are used to derive the frequency equation. Five different boundary conditions such as clamped-clamped, simply supported-simply supported, free-free, clamped-free, clamped-simply supported are considered in this study. Also, the experimental investigation is presented to validate the theoretical results.

• 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.