• Composites Research
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• 제13권3호
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• pp.21-29
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• 2000

The optimum design of hybrid laminated composites for iso-strain structure has been studied by controling fiber orientations and thicknesses of each layer. Fiber orientations and thicknesses of each layer for iso-strain structure were designed. Combining the laminates of each layer of different reinforcing material, the constitutions of hybrid laminated composite for iso-strain structure were obtained. All these calculations were formed on computer systems, automatically for the hybridization. Using the data of some specific laminated composite such as glass and aramid reinforced composites, the constitutions of hybrid laminated composites for iso-strains structure were designed and verified by lamination theory. The strains of each layer of hybrid laminated composites are calculated and they turned out to be good agreements with the results obtained lamination theory.

• 한국안전학회지
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• 제36권3호
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• pp.7-14
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• 2021

Hybrid laminated Al/carbon-fiber-reinforced plastic (CFRP) composites are attracting considerable attention from industries such as aerospace and automobiles owing to their excellent specific strength and specific rigidity. However, when this material is used to fabricate high-pressure fuel storage containers subjected to repeated fatigue loads, fatigue life evaluation for the working load is regulated as an important criterion for operational safety and ease of maintenance. Among the existing evaluation methods for these vessels, the burst test and the hydraulic repeat test require expensive facilities. Thus, the present study aims to develop an improved fatigue life test for Al/CFRP laminated hybrid composites. The test specimen was manufactured using a curved mold considering the shape of a type III high-pressure storage container. The strain-life method was used for fatigue life evaluation, and the life was predicted based on the transition life. The results indicate that the more complex the CFRP stacking sequence, the longer is the transition life. This test method is expected to be useful for ensuring the fatigue safety and economy of hybrid laminate composites.

• Structural Engineering and Mechanics
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• 제70권5호
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• pp.535-549
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• 2019

This study aimed to develop a high-order shear deformation theory to predict the free vibration of hybrid cross-ply laminated plates under different boundary conditions. The equations of motion for laminated hybrid rectangular plates are derived and obtained by using Hamilton's principle. The closed-form solutions of anti-symmetric cross-ply and angle-ply laminates are obtained by using Navier's solution. To assess the validity of our method, we used the finite element method. Firstly, the analytical and the numerical implementations were validated for an antisymmetric cross-ply square laminated with available results in the literature. Then, the effects of side-to-thickness ratio, aspect ratio, lamination schemes, and material properties on the fundamental frequencies for different combinations of boundary conditions of hybrid composite plates are investigated. The comparison of the analytical solutions with the corresponding finite element simulations shows the good accuracy of the proposed analytical closed form solution in predicting the fundamental frequencies of hybrid cross-ply laminated plates under different boundary conditions.

• Composites Research
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• 제19권2호
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• pp.20-27
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• 2006

부직포를 이용한 하이브리드 복합재료는 일반적인 섬유강화 적층복합재료의 기계적 특성을 개선하기 위하여 개발되었다. 부직포 하이브리드 프리프레그는 전형적 FRP 프리프레그와 부직포 프리프레그로 이루어전 있다. 부직포 프리프레그는 부직포와 수지의 조합에 의해 만들어진다. 부직포는 단섬유가 평면상에 불규칙적으로 분산되어 배치된 형상이다. 부직포를 이용한 하이브리드 프리프레그의 개발목적은 (i) 적층간의 층간특성(층간파괴인성 및 층간강도)을 향상시키고, (ii) 저비용으로 재료의 기계적 강도에 대한 신뢰성을 개선하며, (iii) 복합적층판에서 강화가 요구되는 층에 인성과 강도를 부여함에 있다. 상기의 목적을 달성하기 위하여 부직포층의 기포를 감소시키기 위한 제조기술을 제안하였다. 그 결과, 부직포를 이용한 하이브리드 개념을 도입함으로써 복합적층판의 층간파손특성이 크게 개선되었다.

• Composites Research
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• 제23권2호
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• pp.40-47
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• 2010

본 논문에서는 복합 반응면 기법을 제안하고 성능을 고찰하였다. 복합 반응면 기법은 MPP의 좌표를 기준으로 하여 근사모델을 반복 계산하는 기법이다. 성능을 검증하기 위해 비선형 함수와 복합재 적층판에 대하여 신뢰성 해석 기법을 적용하여 파괴확률, MPP(Most Probable failure Point), 신뢰도 지수를 계산하고 일반적인 반응면 기법의 결과와 비교하였다. 파괴확률은 비선형 한계상태식을 가정하고 임의의 파괴 기준을 정의하여 계산하였다. 제안한 복합 반응면 기법을 이용하여 파괴확률을 계산한 결과 일반적인 반응면 기법보다 향상된 성능을 나타내었다.

• 한국분말재료학회지
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• 제20권4호
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• pp.285-290
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• 2013

$Ti_2AlN$ composites are a laminated compounds that posses unique combination of typical ceramic properties and typical metallic(Ti alloy) properties. In this paper, the powder synthesis, SPS sintering, composite characteristics and machinability evaluation were systematically conducted. The random orientation characteristics and good crystallization of the $Ti_2AlN$ phase are observed. The electrical and thermal conductivity of $Ti_2AlN$ is higher than that of Ti6242 alloy. A machining test was carried out to compare the effect of material properties on micro electrical discharge drilling for $Ti_2AlN$ composite and Ti6242 alloy. Also, mixture table as a kind of tables of orthogonal arrays was used to know how parameter is main effective at experimental design. Consequently, hybrid $Ti_2AlN$ ceramic composites showed good machining time and electrode wear shape under micro ED-drilling process. This conclusion proves the feasibility in the industrial applications.

• Steel and Composite Structures
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• 제28권4호
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• pp.495-508
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• 2018

In this paper, the effect of matrix cracks on the buckling of a hybrid laminated plate is investigated. The plate is composed of carbon nanotube reinforced functionally graded (CNTR-FG) layers and conventional fiber reinforced composite (FRC) layers. Different distributions of single walled carbon nanotubes (SWCNTs) through the thickness of layers are considered. The cracks are modeled as aligned slit cracks across the ply thickness and transverse to the laminate plane, and the distribution of cracks is assumed statistically homogeneous corresponding to an average crack density. The first-order shear deformation theory (FSDT) is employed to incorporate the effects of rotary inertia and transverse shear deformation, and the meshless kp-Ritz method is used to obtain the buckling solutions. Detailed parametric studies are conducted to investigate the effects of matrix crack density, CNTs distributions, CNT volume fraction, plate aspect ratio and plate length-to-thickness ratio, boundary conditions and number of layers on buckling behaviors of hybrid laminated plates containing CNTR-FG layers.

• 한국안전학회지
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• 제34권3호
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• pp.1-7
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• 2019

A variety of composite materials are applied to industries for the realization of light weight and high strength. Fiber-reinforced composites have different strength and range of application depending on the weaving method. The mechanical performance of CFRP(Carbon Fiber Reinforced Plastic) in many areas has already been demonstrated. Recently, the application of hybridization has been increasing in order to give a compensation for brittleness of CFRP. Target materials are UHMWPE (Ultra High Molecular Weight Polyethylene), which has excellent cutting and chemical resistance, so it is applied not only to industrial safety products but also to places that lining performance is expected for household appliances. In this study, the CFRP and UHMWPE of plain weave, which are highly applicable to curved products, were molded into laminated hybrid composite materials by autoclave method. The mechanical properties and the mode I failure behavior between the layers were evaluated. The energy release rate G has decreased as the initial crack length ratio increased.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.264-267
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• 2005

Impact damages are very important in the perspective of residual strength of composite structures such as aircrafts, ships, and trains because those damages are sometimes not visible on the surface of the point of impact and the impact resistance of laminated composites is usually not so high. Thus, the impact characteristics of laminated composites should he investigated for the safety of composite structures. This paper investigates the low-velocity impact and damage detection conducted on woven carbon/epoxy laminates. Experimental results show that the type of damage is dependent on the impact energy level and the delamination area becomes larger as the impact energy increases.

• 한국안전학회지
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• 제35권5호
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• pp.9-14
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• 2020

In order to realize high strength and light weight for various industrial facilities and structural materials, various new materials are applied to product design. Among them, CFRP has excellent specific strength and non-rigidity, and the scope of use is expanding throughout the industry, such as mobility products and building materials. GFRP is cheaper than CFRP, and has excellent specific strength and non-rigidity, and has excellent heat resistance and sound insulation, so it has been adopted as a core material for flooring and interior flooring. CFRP of twill weave structure has better resistance to deformation of fiber than plain weave structure, so the outermost layer is applied as twill weave structure in product design. After fabrication with DCB specimens, Mode I fracture toughness was evaluated according to the crack length. As the crack length increases, the energy release rate and stress intensity factor values tended to decrease overall.