• Composites Research
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• 제14권1호
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• pp.22-29
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• 2001

본 논문의 목적은 샌드위치 구조물의 오토클레이브 성형시 발생하는 승압률, 승온율, 금형 라운드 각도, 코어의 두께, 그리고 결함에 대한 저글 높이의 영향을 결정하고, 하니콤으로 보강된 항공기용 샌드위치 구조의 결함을 최소화시키는 것이다. 결과는 항공기용 샌드위치 구조와 금형 라운드 각도와 같은 금형의 형상, 코어의 두께, 저글의 높이, 그리고 승압률, 승온율과 같은 오토클레이브의 성형 조건이 코어의 무브먼트. 코어의 주름, 프리프레그의 뜨임 현상 그리고 코어의 침하에 영향을 기침을 보여주었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.75-82
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• 2000

A huge offshore structures such as immersed tunnel, ice-resisting wall are continuously subjected to large force from water pressure, wave action and impact loads. Composite steel-concrete structure of sandwich system has profitable advantages for a huge offshore structures. This composite structures should exhibit a high degree of strength and ductility, because of concrete confining effect and the property of steel plate. Therefore, it endures large deformation and absorbs a great deal of energy until failure. In this study, nonlinear analysis for composite steel-concrete structure of sandwich system was carried out, and certify the effects of various parameters, elastic·plastic behavior characteristic, load-carrying and failure mechanism.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.423-427
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• 2005

Sandwich structures, which are composed of a thick core between two thin faces, are commonly used in many engineering applications because they combine high stiffness and strength with low weight. Depending on the application of a particular sandwich structure, various types of cores can be used. The production of sandwich sheets by a rolling process, which is a more efficient and economical approach compared to other types of processes, has become an increasingly important subject of study. In this paper, we have studied the embossing structure of sheet type and developed embossing roll mold with $\Phi3$ pattern and roll forming system.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.316-319
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• 2008

The L-bending of inner-structure bonded sandwich sheet metal is examined by using a bending die attached to the material testing machine. The specimen is composed of top and bottom layers and a middle layer of pyramid-core structure and each layer is bonded by brazing. The variables chosen for experiments were clearance between punch and die, location of bend line on the specimen surface and clamping type of specimen during L-bending. Effects of these variables on deformation of specimen around die-corner radius were investigated. It was shown that the irregular shapes of recess are formed in the inner layer of bended parts and they greatly depend on working conditions.

• Smart Structures and Systems
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• 제20권5호
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• pp.595-605
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• 2017

The present article reported the thermal buckling strength of the sandwich shell panel structure and subsequent improvement of the same by embedding shape memory alloy (SMA) fibre via a general higher-order mathematical model in conjunction with finite element method. The geometrical distortion of the panel structure due to the temperature is included using Green-Lagrange strain-displacement relations. In addition, the material nonlinearity of SMA fibre due to the elevated thermal environment also incorporated in the current analysis through the marching technique. The final form of the equilibrium equation is obtained by minimising the total potential energy functional and solved computationally with the help of an original MATLAB code. The convergence and the accuracy of the developed model are demonstrated by solving similar kind of published numerical examples including the necessary input parameter. After the necessary establishment of the newly developed numerical solution, the model is extended further to examine the effect of the different structural parameters (side-to-thickness ratios, curvature ratios, core-to-face thickness ratios, volume fractions of SMA fibre and end conditions) on the buckling strength of the SMA embedded sandwich composite shell panel including the different geometrical configurations.

• Advances in aircraft and spacecraft science
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• 제4권4호
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• pp.353-369
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• 2017

Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. This includes aircraft, buildings and bridges. Flutter occurs as a result of interactions between aerodynamic, stiffness, and inertia forces on a structure. In an aircraft, as the speed of the flow increases, there may be a point at which the structural damping is insufficient to damp out the motion which is increasing due to aerodynamic energy being added to the structure. This vibration can cause structural failure, and therefore considering flutter characteristics is an essential part of designing an aircraft. Scientists and engineers studied flutter and developed theories and mathematical tools to analyze the phenomenon. Strip theory aerodynamics, beam structural models, unsteady lifting surface methods (e.g., Doublet-Lattice) and finite element models expanded analysis capabilities. Periodic Structures have been in the focus of research for their useful characteristics and ability to attenuate vibration in frequency bands called "stop-bands". A periodic structure consists of cells which differ in material or geometry. As vibration waves travel along the structure and face the cell boundaries, some waves pass and some are reflected back, which may cause destructive interference with the succeeding waves. This may reduce the vibration level of the structure, and hence improve its dynamic performance. In this paper, for the first time, we analyze the flutter characteristics of a wing with a periodic change in its sandwich construction. The new technique preserves the external geometry of the wing structure and depends on changing the material of the sandwich core. The periodic analysis and the vibration response characteristics of the model are investigated using a finite element model for the wing. Previous studies investigating the dynamic bending response of a periodic sandwich beam in the absence of flow have shown promising results.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.73-78
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• 2000

This paper describes the effect of span-to-depth ratio, which describes aspect of cell formed with top diaphragm steel plate, on capacity in composite steel-concrete structure of sandwich system. The span-to-depth ratio \ulcorner load-carrying mechanism and load-distribution capacity of structure. Therefore, stress levels of members and load-resis\ulcorner of system vary according to span-depth ratio. In this study, numerical nonlinear analysis was performed to various ratio for two types(MA, MB) composite structure of sandwich system to analyze the influence of span-to-depth ratio or, behavior. The difference of load-carrying mechanism and stress of members results from analysis results, then bas\ulcorner differences, the effects of span-to-depth ratio on shear capacity, flexural capacity and load-resistance capacity were analyze effects on failure mode and ductility were briefly. As a results of this study, as span-to-depth ratio increases, \ulcorner bottom steel plate and concrete lower. This implies an increase in effective flexural and shear capacity. Therefore lo\ulcorner capacity of structure improves as span-to-depth ratio increases, Especially, the effect is greate in shear than flexural span-to-depth ratio increases, this difference between flexural and shear capacity may change failure mode and ductility. span-to-depth ratio increases capacity increases more than flexural capacity, we should expect that structural behavior mode gradually change from shear to flexural and ductility of structure gradually improves.

• 설비공학논문집
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• 제27권6호
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• pp.307-312
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• 2015

The sandwich panel is commonly used domestically because it's less costly and easier to handle. But fires have frequently occurred in buildings employing sandwich panels, such as the fires in Eecheon cold storage and in Gwangju Pyungdong industrial zone. Sandwich panels with steel plates on their surface prevent fire water from penetrating to the fire source, which makes it difficult to extinguish a fire in a timely manner. Toxic gas generated from some insulation material leads to serious loss of life and property. This study is intended to develop an extinguishing system for sandwich panels, thereby reducing the fire risk. Fire water and volume were determined in the wake of the study on the structure of a sandwich panel extinguishing system, and improvement and testing of the fire characteristics of the sandwich panel. Based on such study and test, a fire model test was conducted. Consequently, the sandwich panel with extinguishing system was proven to have a reduced fire risk, compared to traditional or fire retardant panels.

• Advances in nano research
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• 제9권4호
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• pp.237-250
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• 2020

An accurate plate theory for assessing sandwich structures is of interest in order to provide precise results. Hence, this paper develops Layer-Wise (LW) theory for reaching precise results in terms of buckling and vibration behavior of Functionally Graded Carbon Nanotube-Reinforced Composite (FG-CNTRC) annular nanoplates. Furthermore, for simulating the structure much more realistic, its edges are elastically restrained against in-plane and transverse displacement. The nano structure is integrated with piezoelectric layers. Four distributions of Single-Walled Carbon Nanotubes (SWCNTs) along the thickness direction of the core layer are investigated. The Differential Quadrature Method (DQM) is utilized to solve the motion equations of nano structure subjected to the electric field. The influence of various parameters is depicted on both critical buckling load and frequency of the structure. The accuracy of solution procedure is demonstrated by comparing results with classical edge conditions. The results ascertain that the effects of different distributions of CNTs and their volume fraction are significant on the behavior of the system. Furthermore, the amount of in-plane and transverse spring coefficients plays an important role in the buckling and vibration behavior of the nano-structure and optimization of nano-structure design.

• 한국해양환경ㆍ에너지학회지
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• 제19권1호
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• pp.47-51
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• 2016

2차 보강 접착을 한 F.R.P. sandwich 보에 대한 굽힘 거동 특성을 실험적으로 연구하였다. 굽힘 실험을 위해 시편의 면재는 chopped mat 300-450, roving clothes 570과 심재는 urethane foam core, resin은 불포화 polyester 713-bp 선박용을 사용하였고 Resin과 Fiber의 비율을 55 대 45로 하여 제작하였다. 이 연구의 주요 목적은 double-strap-joint 로 2차 보강한 샌드위치 보의 정확한 굽힘 거동특성을 알기 위해서이고 2차 보강 접착을 이용한 sandwich 구조의 설계, 유지 및 보수 시의 2차 보강 ply의 두께 및 길이 결정을 제안했다.