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문창권(Chang-Kwon Moon),김영대(Young-Dae Kim),노태영(Tae-Young Roh) 한국해양공학회 1998 韓國海洋工學會誌 Vol.12 No.3
Single fiber fragmentation technique was used to evaluate the change of interfacial properties by degradation of fiber tensile strength in the fiber reinforced composites. The influences of fiber tensile strength on the interfacial properties have been evaluated by the fragmentation specimens(weak fiber samples) of glass fiber/epoxy resin that was made using the pre-degraded glass fiber in distilled water at 80℃ for specified periods. The effects of the immersion time on the interfacial properties in the distilled water at 80℃ also have been evaluated by the fragmentation specimens(original fiber samples) of glass fiber/epoxy resin that was made using the received glass fiber.<br/> As the result, the tensile strength of glass fiber was decreased with the increasing of the treatment time in the distilled water at 80℃ and the interfacial shear strength was independent of the change of the glass fiber strength in the single fiber fragmentation test. But in the durability test using the single fiber fragmentation specimen, interfacial shear strength decreased with the increasing of the immersion time in distilled water at 80℃. And it turned out that the evaluating of interfacial shear strength using original fiber tensile strength was valuable in the durability test for the water environment by the single fiber fragmentation technique.
문창권(CHANG-KWON MOON),최희락(HEE-LACK CHOI),이봉(BONG LEE) 한국해양공학회 2000 韓國海洋工學會誌 Vol.14 No.3
This study has been investigated about the influence af moisture environment on the mechanical properties in the unidirectional and cross laminated carbon fiber/epoxy and glass fiber/epoxy composites. As a results, it was found that the weight gain of water was increased with the immersion time and the mechanical properties were decreased with the weight gain af water. And it was also. shown that the mechanical properties of carbon fiber/epoxy laminates were better than those of glass fiber/epoxy laminates. And a gap af the mechanical properties between the two kinds of laminates was increasing with the immersion time in distilled water af 80℃. Mechanical properties which decreased by moisture absorption in the CF and GF reinforced laminates were recovered up to some extent by drying in oven at 80℃ for 10 days.
문창권(Chang-Kwon Moon),김부안(Bu-Ahn Kim) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.2
In this study, the crack healing effects of Al₂O₃ ceramics based on the heat treatment conditions were investigated. The influence of the additive amounts of SiC nanoparticles and the cycling process of indentation-heat treatment on the crack healing effect of Al₂O₃ ceramics were also examined. Three-point bending tests were carried out and the morphological changes in the fracture surface were observed by using FE-SEM. As a result, heat-treated samples in a vacuum or air atmosphere showed improved bending strengths compared to un-heat treated samples. This means that cracked specimens can be healed by heat treatment in a vacuum or air atmosphere. The crack healing effect of Al₂O₃ ceramics that were heat treated in an air atmosphere was much higher than that of those heat treated in a vacuum. After heat treatment, the Al₂O₃ ceramics with 30 wt% SiC nanoparticles showed a higher bending strength than those with 15 wt% SiC. The cyclic indentation and heat treatment did not remarkably affect the crack healing effect. The SEM images showed that the median crack, indenter mark on the surface, and pores in the fracture surface of a specimen almost disappeared after being heat treated in an air atmosphere.
SiC<SUB>f</SUB>/SiC 복합재의 마모 및 마찰에 의해 발생된 탄성파 특성
문창권(Chang-Kwon Moon),남기우(Ki-Woo Nam) 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.1
SiCf/SiC 복합재를 제작하여, SiCf/SiC 복합재의 섬유배향 방향에 따르는 마모 특성을 평가하고, 마모시에 발생하는 탄성파를 검출하고 분석하였다. SiCf/SiC 복합재는 섬유의 종?횡방향에 의한 마찰계수와 마모 손실은 비슷하였으나, 섬유의 수직방향은 가장 작은 값을 나타내었다. 이것은 섬유의 취성 특성 때문이라 판단되며, 마모손실과 마찰계수는 정비례의 관계를 나타내었다. SiC 단상재의 탁월주파수는 58.6 kHz를 나타내고, SiCf/SiC 복합재의 탁월주파수는 117.2와 136.7 kHz였다. The wear characteristics of SiCf/SiC composites were evaluated according to the alignment direction of the fibers, and the elastic wave-generated friction was detected and analyzed in wearing. The friction coefficient and wear loss were similar in the longitudinal and the transverse direction of the fibers. However, these values were lower in the vertical direction of the fibers because of the brittle nature of the fiber. The friction coefficient and the wear loss were directly proportional to each other. The dominant frequencies were 58.6 kHz for monolithic SiC and 117.2 and 136.7 kHz for SiCf/SiC composites, respectively.
문창권(Chang-Kwon Moon),구자삼(Ja-Sam Goo) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.2
This work has been investigated in order to study the influence of the moisture absorption on the mechanical properties of the glass fiber/epoxy resin composites and the carbon fiber/epoxy resin composites. The types of glass fiber used in the glass fiber/epoxy resin composites were randomly oriented fiber and plain fabric fiber. And carbon fiber/epoxy resin composites was laminated with fabric prepreg which was formed with carbon fiber and epoxy resin. Both composites were immersed up to 100 days in distilled water at 80℃, and then dried up to 3 days in an oven at 80℃. Both composites were measured for the weight gain of water(wt.%) and tensile strength through immersion and dry time.<br/> Consequently, it was found that the tensile strength of the glass fiber/epoxy resin composites and the carbon fiber/epoxy resin composites were reduced proportionally to the moisture absorption rate. Also, the tensile strength of glass fiber composites was decreased more than that of the carbon fiber composites. Additionally. it was found that the tensile strength of all composites which decreased by moisture absorption were partly recovered by drying in an oven at 80℃.
탄소섬유강화 에폭시수지의 기계적 성질에 미치는 나노입자크기의 영향
문창권(Chang-Kwon Moon),김부안(Bu-Ahn Kim) 한국해양공학회 2015 韓國海洋工學會誌 Vol.29 No.2
TiO₂ nanoparticles can be used to improve the performance of carbon fiber-reinforced epoxy resin composites. In this study, the effect of the size of TiO₂ nanoparticles on the mechanical properties of carbon fiber-reinforced epoxy resin composites was investigated. The size of the TiO₂ nanoparticles was easily controlled using heat treatment. The size of the TiO₂ nanoparticles for this study were20nm, 100nm, and 200nm. Three types of carbon fibers with different diameters were also used in this study. The carbon fiber-reinforced epoxy resin composites with 20-nm TiO₂ powder showed the highest tensile strength compared to the other types of CFRP, regardless of the fiber maker or fiber diameter. The size of the TiO₂ powder and the diameter of the carbon fiber strongly affected the interfacial properties of all kinds of CFRP in this study.