• Journal of Korean Society of Steel Construction
• /
• v.16 no.4 s.71
• /
• pp.493-500
• /
• 2004

In this study, the effects of ring stiffeners for buckling of cylindrical shells with composite materials were analyzed. The finite element method was used: 3-D beam elements were used for stiffeners and flat shell elements were used for cylindrical shells and were improved by introducing a substitute shear strain. The ring stiffeners were of the transverse rib type. The buckling behaviors of the cylindrical shells were analyzed based on various parameters, such as locations and sizes of stiffeners, diameter/length ratios and boundary conditions of shells, and fiber-reinforced angles. Effective reinforcement was examined by understanding the exact behaviors for buckling. The results of the analysis may serve as references for designs and future investigations.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.10
• /
• pp.1807-1815
• /
• 1992

The vibration characteristic of thin laminated orthotropic cylindrical shell is investigated based on the Donnell theory. The Rayleigh-Ritz variational procedure is employed. For the variety of shell end conditions, the beam characteristic function is used for the axial mode function. The result of the present analysis is in good agreement with some available analytical results and NASTRAN and BOSOR4 calculations. In the present study, the relation between natural frequencies and orthotropic parameter k is investigated. Introducing the frequency parameter, this study shows that the frequency parameter increases as the orthotropic parameter k approaches to one.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.5 no.3
• /
• pp.178-182
• /
• 1981

쉘이 복합재로 제작되었거나 보강재를 사용하였을때에는 쉘요소의 역학적 특성은 방향성을 가지게 된다. 이 논문에서는 선형관계식을 사용하여 동적 표면가동을 받는 이방성원통쉘의 안정성을 고려하여 다루었다. 재료의 이방성을 고려하여 3방향 즉, 축방향, 둘레방향 및 반경향의 실성항이 포함된 운동방장실을 유도하였다. 동적 안전성의 해석은 Bolotin 의 방법을 따랐으며 근사해를 행렬식행으로 제시하였다. 수직열로 외압을 받는 원통쉘의 좌단을 다루었으며 본 이론과 고전이론 사이의 차이점을 검토하였다.

• Composites Research
• /
• v.30 no.6
• /
• pp.338-342
• /
• 2017

In this paper, evaluation method of structural integrity of cylindrical composite lattice structures was conducted. A finite element analysis was used to evaluate the structural integrity of composite lattice structures. In order to verify the optimal finite element in the evaluation of the structural integrity, finite element models for cylindrical composite lattice structure were generated using beam, shell and solid elements. The results of the finite element analyses with the shell and solid element models showed a good agreement. However, considerable differences were found between the beam element model and the shell and solid models. This occurred because the beam element does not take into account the degradation of the mechanical properties of the non-intersection parts of cylindrical composite lattice structures. It was found that the finite element analysis of evaluation of structural integrity for cylindrical composite lattice structures have to use solid element.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.49 no.3
• /
• pp.19-24
• /
• 2012

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.3
• /
• pp.514-526
• /
• 1992

본 연구에서는 Taguchi 방법에 사용된 직교배열 이용 실험 계획법에 의한 최 적화 방법으로 보강된 복합재 쉘 구조의 좌굴강도 최적화를 수행하고 타당성을 고찰하 였다.한 방향의 압축하중을 받는 단순 지지된 복합재 평판과 Cut-out을 가진 원통 형 판넬의 보강재 및 섬유방향 최적 설계에 본 방법을 적용시켜 본 결과, 현저한 설계 개선과 아울러 각 설계 변수가 좌굴강도에 미치는 영향을 파악할 수 있었다. 특히 이 방법은 함수의 미분값을 이용한 민감도 해석대신에 함수값의 평균치 분석(ANOM)및 분산 분석(ANOVA)을 사용하기 때문에 설계변수의 변화에 덜 민감한 설계를 얻을 수 있 다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.5
• /
• pp.1436-1444
• /
• 1996

The problem ofinstability of laminated circular cylindrical shell under the action of torsio or lateral pressure is investigated. The analysis is based on the Sander's theory for finite deformations of thin shell. The buckling is elastic for thin compoisite shell nad the geometry is assumed to be free of initial imperfections. The equilibrium equations are obrained by usitn the p[erturbation technique. Solution procedure is based on the Galerkin mehtod. The computer program for numerical results is made for several stacking sequence, length-to-radius ratio, and radius-to-thickness ratio. The numerical results of buckling load are present.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.11a
• /
• pp.9-12
• /
• 2000

This paper deals with the torsional buckling behavior of plain weave GFRP composite cylindrical shells having comparatively small length-to-diameter ratio. Boundary conditions corresponding to clamped ends and simply supported ends are considered. Torsional buckling loads and circumferential mode numbers according to the variation of shell length-to-radius ratio are conformed. To verify the availability of the theoretical results, comparison with the theoretical and experimental results are made.

• Journal of the korean Society of Automotive Engineers
• /
• v.18 no.4
• /
• pp.1-17
• /
• 1996

자동차의 안전에 대한 연구는 객실의 변형제한과 승객의 감속도 축소를 위한 여러가지 구조부재의 에너지 흡수능력 및 흡수 메카니즘을 연구하는데 초점이 맞추어져 왔다. 그 이유는 충돌사고시에 인명을 보호하기 위해서는 차제변형에 의한 물리적 접촉의 회피 뿐 아니라 충돌에너지를 적절히 흡수조절하여 충돌력을 감소시키도록 구조부재를 설계함으로써 충돌안전성이 확보되기 때문이다. 충돌에너지 흡수 특성은 구조부재의 단면 형상과 재질에 따라 달라지며 압괴모드도 구분되어진다. 즉, 복합재료의 압축붕괴특성은 금속이나 플라스틱 재질과는 다르다. 일반적으로 복합재는 재질의 파손으로 에너지가 흡수되지만 금속재는 소성변형으로 에너지를 흡수한다. 이때의 붕괴양상은 작용하중에 따라 축방향 붕괴, 굽힘붕괴, 측면붕괴의 경우는 정규압괴모드(compact mode) 및 불규칙압괴모드(noncompact mode)로 나뉘고, 원통쉘의 경우는 축대칭모드 및 다이아몬드형 모드 등으로 나뉠수 있다. 원형 및 사각 튜브는 광범위한 형상비와 후폭비를 가지도록 제작할 수 있으며 산업전반에 걸쳐 널리 쓰이므로 충돌특성 연구의 대상으로 많은 연구들이 진행되어 왔다. 또한, 충돌특성의 해석을 위한 이론적 모델이 제시되었으며 계속적인 보완이 이루어져 오고 있다.

• Composites Research
• /
• v.15 no.3
• /
• pp.52-61
• /
• 2002

For the aerothermoelastic analysis of cylindrical piezolaminated shells, geometrically nonlinear finite elements based on the multi-field layerwise theory hale been developed. Applying a Han Krumhaar's supersonic piston theory, supersonic flutter analyses are performed for the cylindrical piezolaminted shells subject to thermal stresses and deformations. The possibility to increase flutter boundary and reduce thermoelastic deformations of piezolaminated panels is examined using piezoelectric actuations. Results show that active piezoelectric actuations can effectively increase the critical aerodynamic pressure by retarding the coalescence of flutter modes and compensating thermal stresses.