• Composites Research
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• v.24 no.5
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• pp.9-16
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• 2011

This paper describes the crashworthiness evaluation and performance improvement of tilting train made of sandwich composites. The applied sandwich composite of carbody structure was composed of aluminum honeycomb core and glass/epoxy & carbon/epoxy laminate composite facesheet. Crashworthiness analysis of tilting train was carried out using explicit finite element analysis code LS-DYNA 3D. The 3D finite element model and 1D equivalent model were applied to save the finite element modeling and calculation time for crash analysis. The crash conditions of tilting train were conducted according to four crash scenarios of the Korean railway safety law. It found that the crashworthiness analysis results were satisfied with the performance requirements except the crash scenario-2. In order to meet the crashworthiness requirements for crash scenario-2, the stiffness reinforcement for the laminate composite cover and metal frames of cabmask structure was proposed. Consequentially, it has satisfied the requirement for crash scenario-2.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1231-1235
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• 2010

The tensile failure behavior of polymer matrix composite materials was investigated with the aid of a nondestructive evaluation (NDE) technique. The materials, E-glass fiber reinforced epoxy matrix composites, which are applicable to carbody materials in railway vehicles to reduce weight, were used for this investigation. In order to explain stress-strain behavior of polymer matrix composite sample, the infrared thermography technique was employed. A high-speed infrared (IR) camera was used for in-situ monitoring of progressive damages of polymer matrix composite samples during tensile testing. In this investigation, the IR thermography technique was used to facilitate a better understanding of damage evolution, fracture mechanism, and failure mode of polymer matrix composite materials during monotonic loadings.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.251-255
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• 2005

본 연구는 한국형 틸팅 차량의 하이브리드 복합재 차체에 대한 비용 모델링과 전주기 평가{LCA}를 기존 차체 재질인 스틸 및 알루미늄 재질과 병행하여 수행였다. 원자재 생산에서 차체제작, 수명이 끝나는 시점까지의 사용에 대한 모든 단계에서의 비용을 분석했다. 개발과정을 거쳐 향후 양산 예정인 5년 동안 년간 90대정도의 생산량에 대해 금속 차체, 2종의 복합재 차체에대해 비교하였다. 2종의 복합재 차체는 하이브리드 스틸-복합재 구조와 전체 복합재 차체를 나타낸다. 또한, 이 두 경우 모두에 대해 오토클레이브, 진공 성형, 레진 인퓨젼 공법의 성형에 대해 분석하였다. 제작시의 모든 성형 공법에 대해 하이브리드 차체는 전체 복합재 차체보다 4${\sim}$6 % 비용이 낮았다. 전체 복합재 차체의 경우, 레진 인퓨젼의 경우가 오토클레이브에 대해서는 11%낮은 가장 낮은 제작 비용이 소요되었다. 비용-전주기 분석을 통해 전체 복합재 차체는 가장 높은 제작비용이 소요되고 사회 경제학적 측면에서 전체 전주기 비용과 환경영향은 단순 차량 구입 비용보다 더 중요한 변수이며 전체 복합제 차체가 분명한 최적의 해답 임을 확인하였다.

• Journal of the Korean Society for Railway
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• v.8 no.6 s.31
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• pp.573-580
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• 2005

Model I interlaminar fracture behaviors of the carbon/epoxy composite, one of the candidate composites for a tilting train carbody, were investigate by the use of DCB(Double cantilever beam) specimens. These specimens were made of CF3327 plain woven fabric with epoxy resin, and an artificial starter delamination was fabricated by inserting Teflon film with the thickness of $12.5{\mu}m$ of $25.0{\mu}m$ at the one end of the specimen. Mode I interlaminar fracture toughness was evaluated for the specimens with the different thickness of an inserter. Also delamination propagating behaviors and interlaminar fracture surface were examined through an ooptical travelling scope and a scanning electron microscope. We found that abruptly unstable crack propagation called as stick-slip phenomena was observed. In addition, interlaminar fracture behaviors were affected on the location and the morphology of a crack tip as well as an interface region.

• International Journal of Railway
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• v.1 no.3
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• pp.113-116
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• 2008

The long-tenn exposure of polymeric composite materials to extreme-use environments, such as pressure, temperature, moisture, and load cycles, results in changes in the original properties of the material. In this study, the effect of combined environmental factors such as ultraviolet ray, high temperature and high moisture on mechanical and thermal analysis properties of glass fabric and phenolic composites are evaluated through a 2.5 KW accelerated environmental aging tester. The environmental factors such as temperature, moisture and ultraviolet ray applied of specimens. A xenon-arc lamp is utilized for ultraviolet light and exposure time of up to 3000 hours are applied. Several types of specimens - tensile, bending, and shear specimens that are warp direction and fill direction are used to investigate the effects of environmental factors on mechanical properties of the composites. Mechanical degradations for tensile, bending and shear properties are evaluated through a Universal Testing Machine (UTM). Also, storage shear modulus, loss shear modulus and tan a are measured as a function of exposure time through a Dynamic Mechanical Analyzer (DMA). From the experimental results, changes in material properties of glass fabric and phenolic composites are shown to be slightly degraded due to combined environmental effects.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.852-858
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• 2007

The durability of carbon/epoxy composites under salt water environment was investigated through salt water spray tester. Salt water environment was obtained through salt spray and salt immersion. 5% NaCl solution was used for salt water as natural salt water. Mechanical test was performed to obtain tensile properties, flexural properties, and shear properties of carbon/epoxy composite over 12 months under salt water environment. Dynamic mechanical analyzer was used to investigate thermal analysis properties such storage modulus, loss modulus, and tan ${\delta}$. Also FT/IR test was conducted to investigate a change in chemical structure. According to the results, mechanical properties were found to be slowly degraded as a function of exposure times. Regarding to thermal analysis properties, storage modulus was insensitive to exposure times, but loss modulus was shown to be slightly decreased. Although the shape and location of peak in FT/IR were not much changed, the intensity of peak in FT/IR was affected on exposure times. We also found that salt water immersion was more severe to the durability of carbon/epoxy composite rather than salt water spray.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1103-1108
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• 2005

본 연구는 한국형 틸팅 차량의 복합재 적용 차체에 대한 비용 모델링과 전주기 평가(LCA)를 수행하였다. 원자재 생산에서 차체 제작, 수명이 끝나는 시점까지의 사용에 대한 모든 단계에서의 비용을 분석했다. 5년 동안 년간 90대의 생산량에 대한 금속 차체, 2종의 복합재 차체에 대해 비교하였다. 2종의 복합재 차체는 하이브리드 스틸-복합재 구조와 전체 복합재 차체를 나타낸다. 또한, 이 두 경우 모두에 대해 오토클레이브, 진공 성형, 레진 인퓨젼 공법의 성형에 대해 분석하였다. 제작시의 모든 성형 공법에 대해 하이브리드 차체는 전체 복합재 차체 보다 $4\~6\%$ 비용이 낮았다. 전체 복합재 차체의 경우, 레진 인퓨젼의 경우가 오토클레이브에 대해서는 $11\%$ 낮은 가장 낮은 제작 비용이 소요되었다. 비용-전주기 분석을 통해 전체 복합재 차체는 가장 높은 제작비용이 소요되고 사회 경제학적 측면에서 전체 전주기 비용과 환경영향은 단순 차량 구입 비용보다 더 중요한 변수이며 전체 복합재 차체가 분명한 최적의 해답 임을 확인하였다.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.357-363
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• 2008

This study investigates the durability of carbon/epoxy composites for use on train car bodies under a salt water spray environment. Salt water solution with 5% NaCl, similar to natural salt water, was used for the salt water environmental tests. The specimens were obtained from a composite panel consisting of an epoxy matrix reinforced with T700 carbon fabric. The specimens were exposed to the salt water environment for up to 12 months. Mechanical tests were performed to obtain tensile properties, flexural properties, and shear properties. Dynamic mechanical analysis was used to measure such thermal properties as storage modulus, loss modulus, and tan $\delta$. Also FT/IR tests were conducted to investigate changes in chemical structure with exposure. The results revealed that fiber-dominated mechanical properties were not affected much by exposure time, but matrix-dominated mechanical properties decreased with increasing exposure time. Storage modulus was not very sensitive to exposure time, but glass transition temperature was affected, slightly decreasing with increasing exposure time. Although the peak intensity of FT/IR curves was affected slightly by exposure time, the peak shape and peak location of FT/IR curves were not noticeably changed. Carbon/epoxy composites used for this study were relatively stable to the salt water environment.