• 폴리머
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• 제39권2호
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• pp.219-224
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• 2015

본 연구에서는 현무암섬유의 계면을 황산과 과산화수소로 처리하고 섬유 배향각을 $0^{\circ}$, $0^{\circ}/90^{\circ}$, $0^{\circ}/45^{\circ}/-45^{\circ}$로 달리하여 현무암섬유 에폭시 강화 복합재료의 기계적 특성에 미치는 영향에 대해서 살펴보았다. 기계적 특성은 층간 전단강도(ILSS)와 파괴인성 요소 중 임계응력세기인자($K_{IC}$) 측정을 통하여 고찰하였으며, 섬유의 표면미세구조 변화와 복합재료의 파단면은 주사전자현미경(SEM)으로 관찰하였다. 또한 섬유표면에 계면처리의 여부를 확인하기 위하여 적외선 분광법(FTIR)과 X-선 광전자 분광법(XPS)을 분석하였다. 실험결과 계면처리한 섬유 표면의 -OH 기(hydroxyl)가 증가됨을 확인하였다. 계면처리한 후의 기계적 특성이 계면처리 전의 기계적 특성보다 약 ~100% 증가하였다. 이러한 결과는 표면처리에 의해 섬유와 에폭시 수지 매트릭스 사이의 계면결합력을 증가시킨 것으로 판단된다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.24-28
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• 2002

Composite reinforced fiber materials are used in lots of fields such as a part of aeronautic space, ship, machinery and so on because can make structure wished for necessary condition by control fiber direction and laminated sequence. As the use of advanced composites increase, specific techniques have been developed to repair changed composite structures. In order to repair the damaged part production high quality composite reinforced fiber are completed by control the surrounding temperature and press in autoclave. The quality is influenced heat exposure degree by chemical reaction for precessing. This study considerated influence limit of using by repair structure part and change of properties according to heat exposure degree for repairing.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.252-256
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• 2002

본 연구에서는 유리섬유/나일론 6 복합재료의 계면특성에 미치는 실란계 사이징제의 영향을 조사하기 위하여 microbonding test, short-beam shear test 그리고 dynamic mechanical analysis 방법을 사용하였다. 전자의 미시적인 방법과 후자의 두 가지 거시적인 접근 방법으로부터 얻은 유리섬유/나일론 6 복합재료의 계면특성에 대한 결과가 서로 일치하였다. 상업적으로 사이징 처리된 경우와 비교할 때, 본 연구에 적용된 네 종류의 실란계 사이징제는 유리섬유-나일론 6 수지의 계면결합력을 크게 향상시켰다. 특히, 3-chloropropyltrimethoxysilane (Z-6076)의 사용은 유리섬유/나일론 6 복합재료의 계면전단강도와 층간전단강도를 가장 두드러지게 증가시켰다.

• 유변학
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• 제3권1호
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• pp.22-29
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• 1991

In an effort to predict the long term durability of carbon fiber/epoxy composites in a space environ-ment interlaminar shear strength (ILSS) of the composites was measured as a function of 0.5 MeV electron radiation dosage. For the ILSS measurements a notch method (ASTM D3846) was used with and without side-supports. the supports were used to prevent peeling or bending during the test. The ILSS of both T300/ 5209 longitudinal composite system increases monotonically with radiation when the test is corried out without the support the ILSS of the composites increases initially but then decreases with further radiation. It is also observed that the ILSS of the unsupported case is much lower than that of the supported case. Measurement of epoxy modulus shows that the elastic modulus increases monotonically with radiation. But the breaking strength of the epoxy decreases with radiation. Electron Spectroscopy for Chemcal Analysis shows that the oxygen contents at both the pure epoxy surface and the composite fracture surface increase with radiation dose resulting in the increase of polarity at the interfacial region. This may be a supporting evidence for the increase in the ILSS of the composites.

• 대한안전경영과학회지
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• 제3권1호
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• pp.127-137
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• 2001

Because of the inherent flexibility in their design for improved material properties, composites have wide applications in aerospace vehicles and automobiles. The purpose of this study is to investigate the energy absorption characteristics of CFRf (Carbon Fiber Reinforced Plastics) tubes on static and impact tests. Static compression tests have been carried out using the static testing machine(Shin-gang buckling testing machine) and impact compression tests have been carried out using the vertical crushing testing machine. When such tubes were subjected to crushing loads, the response is complex and depends on the interaction between the different mechanisms that control the crushing process. The collapse characteristics and energy absorption were examined. Trigger and interlaminar number affect the energy absorption capability of CFRP tubes.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.182-185
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• 2004

In this work, the effect of chemical treatments on surface properties of SiC was investigated in mechanical interfacial properties of carbon fibers-reinforced composites. The surface properties of the SiC were determined by acid/base values and contact angles. The thermal stabilities of carbon fibers-reinforced composites were investigated by thermogravimetric analysis (TGA). Also, the mechanical interfacial properties of the composites were studied in interlaminar shear strength (ILSS) and critical strain energy release rate mode II $(G_{IIC})$ measurements. As a result, tile acidically treated SiC (A-SiC) had higher acid value than that of untreated SiC (V-SiC) or basically treated SiC (B-SiC). According to the contact angle measurements, it was observed that chemical treatments led to an increase of surface free energy of the SiC surfaces, mainly due to the increase of the specific (polar) component. The mechanical interfacial properties of the composites, including ILSS and $(G_{IIC})$, had been improved in the specimens treated by chemical solutions. These results were explained that good wetting played an important role in improving the degree of adhesion at interfaces between SiC and epoxy resin matrix.

• Carbon letters
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• 제15권2호
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• pp.125-128
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• 2014

In this study, the effect of stacking sequence on the flexural and fracture properties of carbon/basalt/epoxy hybrid composites was investigated. Two types of carbon/basalt/epoxy hybrid composites with a sandwich form were fabricated: basalt skin-carbon core (BSCC) composites and carbon skin-basalt core (CSBC) composites. Fracture tests were conducted and the fracture surfaces of the carbon/basalt/epoxy hybrid composites were then examined using scanning electron microscopy (SEM). The results showed that the flexural strength and flexural modulus of the CSBC specimen respectively were ~32% and ~245% greater than those of the BSCC specimen. However, the interlaminar fracture toughness of the CSBC specimen was ~10% smaller than that of the BSCC specimen. SEM results on the fracture surface showed that matrix cracking is a dominant fracture mechanism for the CSBC specimen while interfacial debonding between fibers and epoxy resin is a dominant fracture process for the BSCC specimen.

• Advanced Composite Materials
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• 제17권4호
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• pp.373-407
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• 2008

This paper will examine the possibilities of the virtual tests of composite structures by simulating mechanical behaviors by using supercomputing technologies, which have now become easily available and powerful but relatively inexpensive. We will describe mainly the applications of large-scale finite element analysis using the direct numerical simulation (DNS), which describes composite material properties considering individual constituent properties. DNS approach is based on the full microscopic concepts, which can provide detailed information about the local interaction between the constituents and micro-failure mechanisms by separate modeling of each constituent. Various composite materials such as metal matrix composites (MMCs), active fiber composites (AFCs), boron/epoxy cross-ply laminates and 3-D orthogonal woven composites are selected as verification examples of DNS. The effective elastic moduli and impact structural characteristics of the composites are determined using the DNS models. These DNS models can also give the global and local information about deformations and influences of high local in-plane and interlaminar stresses induced by transverse impact loading at a microscopic level inside the materials. Furthermore, the multi-scale models based on DNS concepts considering microscopic and macroscopic structures simultaneously are also developed and a numerical low-velocity impact simulation is performed using these multi-scale DNS models. Through these various applications of DNS models, it can be shown that the DNS approach can provide insights of various structural behaviors of composite structures.

• Composites Research
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• 제15권6호
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• pp.16-23
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• 2002

본 연구에서는 양극산화 처리에 따른 고강도 PAN계 탄소섬유의 표면 특성 변화가 기계적 계면 물성에 미치는 영향을 조사하였다. 탄소섬유의 표면성질은 산.염기도, SEM, XPS, 그리고 접촉각 측정을 통하여 알아보았으며, 복합재료의 기계적 계면 특성은 ILSS와 $K_{IC}$를 통하여 고찰하였다. 탄소섬유 표면의 산도와 $O_{ls}/C_{IC}$가 증가하였는데, 이는 산소관능기의 발달에 기인하고, 양극산화된 탄소섬유의 표면자유에너지의 증가는 극성요소의 증가에 기인하는 것으로 사료된다. ILSS와 $K_{IC}$ 같은 기계적 계면 성질은 양극산화로 향상되어졌는데, 이러한 결과는 좋은 젖음성이 최종 복합재료의 섬유와 에폭시 수지 매트릭스 사이의 계면결합력을 증가시기는 중요한 역할을 하기 때문으로 사료된다.

• Composites Research
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• 제31권6호
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• pp.304-310
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• 2018

오토클레이브 (Autoclave) 성형 공정은 항공산업분야의 복합재 부품 제작에 있어서 매우 안정적이고 중요한 제조방법으로서 자리매김 해왔었지만 오토클레이브가 가진 많은 장점과 함께 단점 또는 제약 사항들을 보여주고 있다. 최근에는 이러한 한계를 극복하기 위하여 다양한 탈 오토클레이브 (OoA, Out-of-Autoclave) 공정들이 연구 개발되고 있는데, 본 연구에서는 탈 오토클레이브 공정 중 하나로서 많은 관심을 받고 있는 액상성형공정 (Liquid Composite Molding)을 사용하여 시편들을 제작하고 이를 오토클레이브 공정으로 제작된 시편과 실험적으로 비교평가하였다. 액상성형공정 중 DB (Double Bagging), CAPRI (Controlled Atmospheric Pressure Resin Infusion) 및 VAP (Vacuum Assisted Process) 공정을 사용하여 시편 제작을 수행하고 내부 기공 함유량, 두께, 유리전이온도, 층간전단강도 및 굽힘강도 시험 평가를 통하여 각 제작 공정에 따른 차이를 확인할 수 있었다. 전체적으로 오토클레이브 성형 시편이 우수한 두께 균일도, 낮은 기공 함유량 및 양호한 기계적 강도 특성을 보였으며, 액상성형공정 중에서는 CAPRI 성형 시편이 DB 및 VAP 성형 시편에 비하여 상대적으로 우수한 특성을 가짐을 확인하였다.