• Composites Research
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• v.31 no.1
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• pp.37-41
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• 2018

The aim of the current work is to characterise a piecewisely-integrated composite bumper beam based on the IIHS bumper crash protocol. IIHS bumper crash FE analysis for an aluminium type bumper beam was carried out to get the information about the dominant loading types at several regions in the bumper beam during crash. In the meantime, robust stacking sequences against tension and compression have been searched for using FE analysis of a coupon type model. After determining most effective stacking sequences for tension and compression, three-point bending simulation was preliminarily carried out to investigate the combination performance of them. Finally, IIHS bumper crash FE analysis for the piecewisely-integrated composite bumper beam, which consisted of the combination of tension effective stacking sequence and compression efficacious stacking sequence, was conducted and the result was compared with other types of composite bumper beams. It was found that the newly suggested piecewisely-integrated composite bumper beam showed superior crashworthy behaviour to those of uni-modal stacking sequence composite bumper beams.

• Composites Research
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• v.13 no.2
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• pp.61-71
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• 2000

Today, the use of composite materials become an essential part in the design and manufacturing process of the flight vehicles to reduce the structural weight. Since the structural properties can be varied largely due to the stacking sequence of ply angles, it is very important problem to determine the optimized ply angles under a design objective. Thus, in this study, the analysis of static aeroelastic optimization of a composite wing has been performed. An analytical system to calculate and optimize tile aero-structural equilibrium position has been developed and incorporated with the genetic algorithm. The effects of stacking sequence on the structural deformation and aerodynamic distribution have been studied and calculated with the condition of minimum structural deformation for a swept-back composite wing. For the set of practical stacking angles, the design results to maximize the performance of static aeroelasticity are also presented.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.59-66
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• 2002

In this paper, we present the simulataneous monitoring of the strain and temperature during cures f various composite laminates using fiber Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPI) hybrid sensors. Three types of graphite/epoxy composite were used : a undirectional laminate, a symmetric cross-ply laminate, and a fabric laminate. Two FBG/EFPI hybrid sensors were embedded in each laminate at different directions and different locations. We performed the real time monitoring of fabrication strains and temperatures at two points within the composite laminates during cure process in an autoclave. Throuhg these experiments, FBG/EFPI sensors proved to be an efficient choice for smart cure monitoring of composite structures.

• Computational Structural Engineering
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• v.6 no.1
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• pp.117-125
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• 1993

In general, the strength and stiffness of laminated composite cylindrical shells are very sensitive to the variation of slenderness parameters, some coupling-stiffness parameters, lamination angles, stacking sequence and number of layers. In this paper, the effects of these factors on the strength and buckling reliabilities of GFRP laminated cylindrical shells are investigated based on the proposed strength and buckling limit state models. As these factors have various and complicated effects on the strength and buckling reliabilities of GFRP laminated cylindrical shells, the results should be incorporated into the design formula such that optimum design technique and design code which provide uniform consistent reliability for balanced design in practice

• Journal of Korea Ship Safrty Technology Authority
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• s.26
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• pp.4-23
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• 2009

선체용 복합재료 및 구조용 접착제와 신공법인 진공 성형법으로 건조한 레저선박에 강화플라스틱 구조기준을 그대로 적용하기에는 무리가 있으며, 따라서 복합재료, 수지, 접착제 및 진공 성형법 등 현장조사를 토대로 복합소재 및 접착제를 이용한 시험편을 제작하여 복합재료의 기계적 특성, 구조용 접착제에 대한 신뢰성 평가 및 국내외 기준 비교 검토를 통한 국내 실정에 적합한 검사기준을 제안하고자 한다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.17-24
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• 2002

인발성형 적층 FRP 복합소재의 재료상수는 일반적으로 시편실험을 통해 구해지고 있으나, 본 논문에서는, 실험에서 구한 탄성계수가 부재일 경우를 위해, Micromechanics와 Classical Laminate Theory (CLT)를 이용한 적층 FRP 복합재료의 탄성계수(E/sub L/과 E/sup b//sub L/) 예측모델을 제시하였다 또한 예측모델로부터 구한 값과 실험으로부터 얻은 실측값을 비교하여 그 적정성을 검증하였고, 예측모델의 민감도 및 확률적인 특성을 구성소재 (Constituents)의 재료특성에 근거해 평가하였다.

• Journal of Korean Association for Spatial Structures
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• v.6 no.4 s.22
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• pp.45-52
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• 2006

FRP laminated plates have strong material-nonlinearity. Through vibration Analysis of FRP laminated plates, the result of nonlinearity analysis is compared with the result of linearity analysis according to stacking angle and squency. This study is a fundamental study about displacement in nonlinearity dynamic behavior of FRP laminated plates.

• Composites Research
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• v.19 no.2
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• pp.20-27
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• 2006

The hybrid composite materials with non-woven tissue (NWT) was developed to improve the mechanical properties of conventional FRP composite materials. The hybrid prepreg with NWT consists of FRP prepreg and NWT prepreg. The NWT prepreg consists of NWT and polymer resin. The NWT has short fibers, discretely distributed with in-plane random orientation fibers. The purposes of this study of hybrid prepreg with NWT are (i) to increase the interlaminar properties(the fracture toughness and strength), (ii) to improve the mechanical properties and reliability, while maintaining a low cost, (iii) to introduce a tough and strong interlayer at critical positions to be required of strength in the laminate. To accomplish the above purposes, a production technique to decrease voids in NWT layers was proposed in this paper. The interlaminar failure characteristics of laminated composite materials was tremendously improved by hybrid concept with NWT.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2001.11a
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• pp.349.2-363
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• 2001

안전성의 측면에서 기계설비 및 구조물의 파손을 유발할 수 있는 재료손상에 대한 평가는 매우 중요하기 때문에, 사용 목적에 부합되는 우수한 첨단재료의 개발과 그 특성을 파악할 필요성이 있다 그 중에서 섬유강화 복합재료는 금속재료보다 높은 비강도와 비강성을 가지며 적층각도, 적층순서 및 경화방법에 따라서 원하는 강도와 강성을 가질 수 있다 특히, 탄소섬유강화복합재료(CFRP)는 스포츠용품에서 최신 항공기의 구조재료에 이르기까지 경량화 관점에서 기존의 재료를 대체해 나가고 있다.(중략)

• Composites Research
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• v.32 no.2
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• pp.108-112
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• 2019

There has been a continuous study on the weight reduction of structure by composites. Unlike isotropic materials, the physical properties of composites vary according to the direction of laminate and the order of lamination. Therefore, in the case of composite ladders, it is essential to perform structural analysis to verify the planned design. In this study, ladder was designed by applying fabric material. In addition, the effect of loading position on the ladder was analyzed through finite element analysis, and structural performance was analyzed by selecting the most problematic location. We analyzed the effect of stacking order on the structural strength of the ladder by analyzing the structure by applying various stacking sequence and measuring the failure value in each layer.