• Composites Research
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• v.26 no.4
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• pp.245-253
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• 2013

In this paper, we developed a theoretical model which is able to predict the tensile strength and elastic modulus of hybrid composites reinforced by two types of randomly distributed discontinuous reinforcements. For this, we considered two known models; One is a prediction model based on the assumption that the composite is reinforced by two types of well aligned continuous reinforcements. The other is a statistical model for the composite which is reinforced by only one type of randomly distributed discontinuous reinforcements. In order to evaluate the validity of accuracy of our prediction model, we measured the strength and elastic modulus of polypropylene hybrid composite reinforced by talc and short glass fiber. We found that the present model drastically enhances the accuracy of strength prediction compared to an existing model, and predicts the elastic modulus within the same order with experimentally measured values.

• Composites Research
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• v.16 no.2
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• pp.33-40
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• 2003

In order to overcome one of the most pronounced shortcomings of conventional laminated composites, such as the low damage tolerance due to delamination, the thermoplastic materials and 3D (three-dimensional) preforms have been utilized in the manufacture of composite materials. From the newly developed process termed as the co-braiding, hybrid yarns of the thermoplastic fibers (PEEK) and reinforcing fibers (carbon) have been fabricated. In order to further enhance the delamination suppression, through thickness fibers have been introduced by way of 3D weaving technique in the fabrication of textile preforms. The preforms have been thermoformed to make composite materials. Complete impregnation of the PEEK into the carbon fiber bundles has been confirmed. For the comparison of mechanical performance of 3D woven composites, quasi-isotropic laminates using APC-2/AS4 tapes have been fabricated. Tensile and compressive properties of both the composites have been determined. Furthermore. the open hole, impact and CAI(Compression After Impact) tests were also carried out to assess the applicability of 3D woven textile reinforced thermoplastic composites in aerospace structures.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.87-90
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• 2005

This paper presents an evaluation of the effect of titanium dioxide nanoparticles in sulfonated poly(ether ether ketone) (SPEEK) with sulfonation degree of 57%. A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxide nanoparticles content. Their water uptake, methanol permeability and proton conductivity as a function of temperature were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and water swelling. It is also found that increase in inorganic oxide content leads to decrease of methanol permeability. In terms of morphology, membranes are homogeneous and exhibit a good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with standard nafion membrane.

• Composites Research
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• v.26 no.3
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• pp.165-169
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• 2013

This work presents the tensile properties and water uptake behavior of plasma treated abaca fibers reinforced epoxy composites. The composites were prepared by vacuum assisted resin transfer molding. The effects of treatment on tensile properties and sorption characteristics of abaca fiber composites in distilled water and salt solution at room temperature were investigated. The tensile strength of the composites increased with plasma treatment. With plasma treatment, an improvement of 92.9% was obtained in 2.5 min exposure time in plasma. This is attributed to high fiber-matrix compatibility. Less improvement on tensile properties of hybrid treatment of sodium hydroxide and plasma was obtained. However, both treatments reduced overall water uptake in distilled water and salt solution. Hydrophilicity of the fibers decreased upon plasma and sodium hydroxide treatment, which decreases water uptake.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.640-641
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• 2006

To improve the mechanical properties of WC-Co cemented carbides, the dual composite was studied. The compositions of granule and matrix were nano-sized WC-6 wt% Co(granule) and normal sized WC-20 wt% Co(matrix), respectively. The granules were grouped 50, 100 and $150\;{\mu}m$ and mixed with WC and Co powders as the volume fractions of granule to matrix were 50 to 50, 40 to 60 and 30 to 70. These compacts were sintered at $1380^{\circ}C$ for 10 minutes in vacuum. The microstructure, transverse rupture strength and wear resistance were investigated.

• Composites Research
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• v.20 no.3
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• pp.8-16
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• 2007

Bending collapse of light-weight square tubes used for vehicle structure components is a dominant failure mode in oblique collision and rollover of vehicles. In this paper bending performances of aluminum-GFRP hybrid tube beams were evaluated in relation with bending deformation behavior and energy absorption characteristics. Aluminum/GFRP hybrid tube beams fabricated by inserting adhesive film between prepreg and metal layer were used in the bending test. Failure mechanisms of hybrid tubes under a bending load were experimentally investigated to analyze the bending performance as a function of ply orientation and composite layer thickness. Ultimate bending moments and energy absorption capacity of hybrid tube beams were obtained from the measured load-displacement corves. It was found that aluminum/GFRP hybrid tubes could be converted to rather stable collapse mode showing excellent energy absorption capacity in comparison to the pure aluminum tube beams. In particular, the hybrid tube beam with $[0^{\circ}/90^{\circ}]s$ composite layer showed a large improvement by about 78% in energy absorption capacity and by 29% in specific energy absorption.

• Composites Research
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• v.37 no.3
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• pp.170-178
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• 2024

This study proposes a hybrid composite where a thin copper film (Cu film) is embedded in carbon fiber reinforced plastic (CFRP), and quantum annealing is applied to derive the combination of Cu film placement that maximizes the through-thickness thermal conductivity. The correlation between each ply of CFRP and the Cu film is analyzed through finite element analysis, and based on the results, a combination optimization problem is formulated. A formalization process is conducted to embed the defined problem into quantum annealing, resulting in the formulation of objective functions and constraints regarding the quantity of Cu films that can be inserted into each ply of CFRP. The formulated equations are programmed using Ocean SDK (Software Development Kit) and Leap to be embedded into D-Wave quantum annealer. Through the quantum annealing process, the optimal arrangement of Cu films that satisfies the maximum through-thickness thermal conductivity is determined. The resulting arrangements exhibit simpler patterns as the quantity of insertable Cu films decreases, while more intricate arrangements are observed as the quantity increases. The optimal combinations generated according to the quantity of Cu film placement illustrate the inherent thermal conductivity pathways in the thickness direction, indicating that the transverse placement freedom of the Cu film can significantly affect the results of through-thickness thermal conductivity.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.617-619
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• 2008

Inorganic-organic hybrid multilayers were formed on the plastic substrate to enhance the barrier properties of substrate to water vapor and oxygen transport. Plasma pretreatment of substrate with $Ar/O_2$ lead to adhesion improvement and the densification of inorganic layer on the substrates. Combination of $SiO_xN_y$ layer and silanenanoclay composite layer offered quite good barrier properties (WVTR and OTR) to PES substrate.

• Journal of the Korean Society of Safety
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• v.35 no.5
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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.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.53-58
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• 2012

In order to improve the surface hardness of transparent plastic films, an organic-inorganic hybrid coating solution was sunthesized by the sol-gel method. Coating solutions that were prepared colloidal silica (CS), poly methyl methacrylate (PMMA), vinyltrimethoxysilane (VTMS), and [3-(methacryloyloxy)]propyltrimethoxy silane (MAPTMS) was varied with synthesizing parameters such as kinds of organic silane and weight ratio of CS to PMMA. Such coating solution was bar coated on the PET film, cured, and investigated on the chemical and physical properties of coating film. The organic-inorganic hybrid coating solutions have better properties at the pencil hardness and adhesion of coating film than those of an organic material such as PMMA.