Bonding Performance of Glulam Reinforced with Textile Type of Glass- and Aramid-Fiber, GFRP and CFRP

Keon Ho Kim,Soon Il Hong 한국목재공학회 2011 목재공학 Vol.39 No.2

To evaluate the bonding performance of reinforced glulam, the textile type of glass fiber and aramid fiber, and the sheet type of glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP) were used as reinforcements. The reinforced glulam was manufactured by inserting reinforcement between the outmost and middle lamination of 5ply glulam. The types of adhesives used in this study were polyvinyl acetate resins (MPU500H, and MPU600H), polyurethane resin and resorcinol resin. The block shear strengths of the textile type in glass fiber reinforced glulam using MPU500H and resorcinol resin were higher than 7.1 N/mm2, and these glulams passed the wood failure requirement of Korean standards (KS). In case of the sheet types, GFRP reinforced glulams using MPU500H, polyurethane resin and resorcinol resin, and CFRP reinforced glulams using MPU500H and polyurethane resin passed the requirement of KS. The textile type of glass fiber reinforced glulam using resorcinol resin after water and boiling water soaking passed the delamination requirement of KS. The only GFRP reinforced glulam using MPU500H after water soaking passed the delamination requirement of KS. We conclude that the bonding properties of adhesive according to reinforcements are one of the prime factors to detennine the bonding performance of the reinforced glulam.

Mechanical and Interfacial Properties of Flax Fiber-reinforced Plastic Composites Based on a Chemical Modification Method

Hongguang Wang,HAO WU,Lanjie Yang,Guanglong Yu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.7

Due to growing interest in environmental protection, eco-friendly fibers with high specific strength and low costare widely used to reinforce matrix materials. Flax fiber is a natural renewable plant fiber that originates from the phloem offlax. Flax fibers not only have the characteristics of other natural fibers but also have the outstanding mechanical properties ofnatural fibers. However, due to the large amount of hydrophilic hydroxyl groups on the surface, the hydrophilic absorption offlax fibers is large, and the wet-heat durability of the composite is poor, which limits the use of flax fiber as a reinforcementmaterial in civil engineering applications. In this study, based on the research results of flax fiber, a flax fiber sheet wasgrafted with multiwalled carbon nanotubes, a silane coupling agent and nano-TiO2 particles. The effect of different treatmentmethods and process parameters on the mechanical and interfacial properties of flax fiber-reinforced plastic (FFRP)composites materials was studied. The results show that the FFRP composites grafted with multiwalled carbon nanotubeshave higher tensile strength and interlaminar shear strength than those grafted with the same content of nano-TiO2 particles. Flax fiber composites with improved interfacial properties can be obtained by grafting flax fiber sheets, but the content ofparticles on the flax fiber surface should not exceed 2.0 wt.% of nano-TiO2 and multiwalled carbon nanotubes. Under thistreatment, the FFRP composites have improved properties, such as tensile strength, interlaminar shear strength and glasstransition temperature.

유리섬유 조합에 따른 보강 집성재 볼트접합부의 전단강도 특성

김건호 ( Keon Ho Kim ),송요진 ( Yo Jin Song ),홍순일 ( Soon Il Hong ) 한국목재공학회 2013 목재공학 Vol.41 No.1

In order to know the shear performances of a bolted connection in reinforced glulam depending upon the combination of textile glass fiber, a tensile-type shear test was conducted. Textile glass fiber was used as a reinforcement, whose glass fiber arrangement was a plain weaving type or a diagonal cloth type. Reinforced glulam was made up of 5 plies and it was produced by inserting and laminating the plies between laminas depending upon a changed insert position and combination form of textile glass fiber. Tensile-type shear test specimens were a steel plate insert-type and joined at end-distance 7D with bolts whose diameter 12 or 16 mm. In textile glass fiber reinforced glulam, whose volume ratio was 1%, the yield shear strength of a 12 mm bolted connection increased by 10% when a test specimen had reinforced internal layers than when external layers were reinforced. As for textile glass fiber reinforced glulam, whose volume ratio was 2%, the yield shear strength of a 12 mm bolted connection increased significantly by about 22% compared to the bolted connection of non-reinforced glulam, and the yield shear strength of a 16 mm bolted connection was improved by about 20% compared to the bolted connection of non-reinforced glulam.

Flow-induced Orientations of Fibers and Their Influences on Warpage and Mechanical Property in Injection Fiber Reinforced Plastic (FRP) Parts

Chao-Tsai Huang,Jia-Hao Chu,Wei-Wen Fu,Chia Hsu,Sheng-Jye Hwang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.3

During the past two centuries, due to too fast growth of the human population, the pollution made by human has seriously impacts on our environment, particularly, for the CO2 emission. To diminish the CO2 emission problem, one of the effective solutions is applying lightweight material, such as the fiber-reinforced plastics (FRP), to replace metal in the manufacturing of transportation vehicles. However, since the reinforced function of the fibers inside plastic matrix is very complex, it is not easy to be visualized and managed. Specifically, the connection from microstructures of the fibers to the physical properties of the final product is far from our understanding. In this study, we have proposed a benchmark with three standard specimens based on ASTM D638 with different gate designs. This system is used to study the fiber microstructures and associated mechanical properties using numerical simulation and experimental studies. Results showed that the tensile properties (including tensile modulus and tensile stress) of all three ASTM standard specimens can be improved significantly in the appearance of the fibers. Moreover, the tensile properties variation of the finished parts associated with the microstructures of the short fibers based on the gate design have been also investigated. Specifically, the tensile modulus and the strength of the Model I are greater than that of Model II, while Model III is much less than others because of its double gate effect. The reason why the tensile modulus and the strength of the Model I is greater than that of Model II is due to some entrance effect. That entrance effect will further provide flow-induced fiber orientation to melt and then enhance the tensile properties of Model I. To confirm the observation, a series simulation and experimental studies have been performed. Specifically, the fiber orientation distribution is predicted using CAE, and verified using micro-CT scan and image analysis by Avizo software. Hence, the correlation from fiber microstructure feature (particularly in fiber orientation) to tensile modulus and tensile stress for fiber reinforced thermoplastic (FRP) in injection molding process can be validated.

국부 열손상을 받은 복합재료의 탄성파특성

남기우(KI-WOO NAM),김영운(YOUNG-UN KIM) 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.4

Fiber-reinforced composites are extensively used in electronic, ship and aerospace applications due to their high strength and high toughess. In these applications, they are often subjected to localized heat damage due to various sources. In order to ensure their reliability, it is important to predict their residual properties using nondestructive evaluation thchniques. Fabric fiber composite specimens were manufactured with six layers of the glass-fiber prepreg and the carbon-fiber prepreg, respectively. The specimens were subjected to a localized heat damage using a heated copper tip with a diameter of 10㎜ at 350℃(CFRP) and 300℃(GFRP), respectively. The specimens were then subjected to tension tests while acoustic emission (AE) activities of specimens were collected. The AE activity of all specimens showed three types of distinct frequency regions. Those are matrix cracking, failure of the fiber/matrix interface and fiber breakage.

자동차 부품의 강성 보강을 위한 섬유강화 플라스틱 사출성형품의 섬유 배향 및 기계적 특성에 관한 연구

정의철,김용대,이정원,홍석관,이성희 한국금형공학회 2022 한국금형공학회지 Vol.16 No.4

Fiber-reinforced plastics(FRPs) have excellent specific stiffness and strength, so they are usually used as automotive parts that require high rigidity and lightweight instead of metal. However, it is difficult to predict the mechanical properties of injection molded parts due to the fiber orientation and breakage of FRPs. In this paper, the fiber orientation characteristics and mechanical properties of injection molded specimens were evaluated in order to fabricate automotive transmission side covers with FRPs and design a rib structure for improvement of their rigidity. The test molds were designed and manufactured to confirm the fiber orientation characteristics of each position of the injection molded standard plate-shaped specimens, and the tensile properties of the specimens were evaluated according to the injection molding conditions and directions of specimens. A gusset-rib structure was designed to improve the additional structural rigidity of the target products, and a proper rib structure was selected through the flexural tests of the rib-structured specimens. Based on the evaluation of fiber orientation and mechanical characteristics, the optimization analyses of gate location were performed to minimize the warpage of target products. Also, the deformation analyses against the internal pressure of target product were performed to confirm the rigidity improvement by gusset-rib structure. As a result, it could be confirmed that the deformation was reduced by 27~37% compared to the previous model, when the gusset-rib structure was applied to the joining part of the target products.

섬유강화재 함유율에 따른 FRTP의 기계적 특성 및 연소특성에 관한 연구

김경진,엄상용,김기환 한국화재소방학회 2019 한국화재소방학회논문지 Vol.33 No.3

본 연구에서는 섬유강화 열가소성 플라스틱 복합재료(Fiber Reinforced thermo plastics, FRTP)의 기계적 특성 및 화재 위험성 예측을 위한 연소특성을 평가하였다. 폴리카보네이트와 나일론에 섬유강화재로 유리섬유와 탄소섬유를각각 0~40 wt% 혼합하여 특성변화를 실험한 결과, 섬유강화재의 함유율이 증가할수록 비강도와 열변형 온도가 증가하였고 난연성은 유리섬유 함유율이 30 wt% 이상인 경우 V-0 등급을 보였다. 연소특성의 경우 섬유강화재의 함유율이 증가함에 따라 착화시간도 비례하여 증가하였으며, 최대 열방출율은 섬유강화재를 40 wt% 함유 시 함유하지 않았을 때보다 폴리카보네이트는 약 51%, 나일론은 약 24% 수준으로 낮아졌다. CO 발생율은 일정시간까지 감소하다가 증가하는 경향을 보이며, 이는 시간이 지남에 따라 불완전연소에 의한 것으로 판단된다. CO2 발생율은 열방출율과 매우 유사한 경향을 보이며, 최대 CO2 발생율은 섬유강화재를 40 wt% 함유 시 함유하지 않았을 때보다 폴리카보네이트는 약 50%, 나일론은 약 28% 수준으로 낮아졌다. To examine the mechanical and combustion characteristics of FRTP, either polycarbonate or nylon were used as a matrix,and either glass fiber or carbon fiber were used as the fiber reinforcement. The fiber reinforcement content wasdifferentiated at 0~40 wt%. The tensile strength and heat distortion temperature increased with increasing reinforcementcontent. When the fiber reinforcement content was above 30 wt%, the flammability rating showed V-0. As the fiberreinforcement content increased from 0 to 40 wt%, the peak heat release rate of polycarbonate decreased by approximately51% and that of nylon decreased by approximately 24%. The rate of CO generation decreased for a period of time, andthen increased. This appears to have resulted from incomplete combustion. The rate of CO2 generation shows a similartendency with the heat release rate. As fiber reinforcement content levels increased from 0 to 40 wt%, the CO2 peak rateof polycarbonate generation decreased by approximately 50% and that of nylon decreased by 28%.

CFRP 일방향 45도 배향각 프리프레그의 회전수 변화에 따른 HSS, TiAIN 드릴 절삭에 관한 연구

김선범 한국기계기술학회 2023 한국기계기술학회지 Vol.25 No.5

Prepreg is an abbreviation of Preimpregnated Materials. It is a sheet-type product in which a matrix is ​​impregnated with reinforced fiber. The prepreg has very different properties depending on the orientation of the fibers and the weaving method, and the orientation of the fibers plays an important role in determining the mechanical strength of CFRP. Short and randomly oriented reinforcing fibers show isotropy, while long, unidirectional reinforcing fibers exhibit anisotropic behavior and are strongest when the applied load is parallel to the reinforcing fibers. Classification by the direction of the fiber is divided into unidirectional, orthogonal, multiaxial, and the like. Uni-directional refers to a state in which almost all fibers in the fabric are aligned in one direction. When the fibers used as reinforcing materials are aligned in one direction, the fibers are used in a straight line without twisting during the fabric production process, and there is an advantage in that the amount of fibers used as a whole can be minimized. A uni-directional prepreg exhibits different cutting forces depending on the stacking orientation angle. In this experiment, the optimal cutting conditions for a uni-directional prepreg 45 degree orientation angle specimen are presented.

유리섬유 강화 플라스틱용 다중벽 탄소나노튜브/유리섬유 복합충전재의 제조

강민성,김훈식,김성택,진형준,Kang, Min-Sung,Kim, Hun-Sik,Kim, Seong-Taek,Jin, Hyoung-Joon 한국섬유공학회 2009 한국섬유공학회지 Vol.46 No.3

We report a simple and mass-producible method for incorporating multiwalled carbon nanotubes (MWCNTs) on the surface of chopped glass fibers for applications to glass-fiber reinforced plastics. The MWCNTs were synthesized by thermal CVD. In order to eliminate impurities in the MWCNTs (such as metallic catalysts), the MWCNTs were treated in acid mixture (sulfuric acid/nitric acid=3:1 (v/v)) at $70^{\circ}C$ for 24 h, followed by a reflux process in 5 M HCl at $120^{\circ}C$ for 6 h. The multiple fillers, such as MWCNTs/glass fibers for reinforcement, were prepared by dipping the chopped glass fibers in a well-dispersed alcohol MWCNT solution (0.1 wt%). Field emission scanning electron microscopy showed MWCNTs generated on the microscopic glass fibers. Moreover, the MWCNTs piled up on the surface of the glass fibers with increasing absorption time. The mechanical properties of the ABS were enhanced by the incorporation of MWCNT-coated glass fibers.

탄소섬유 산화 현상을 고려한 탄소복합재료의 섬유체적비 측정법

김윤호 ( Yunho Kim ),( Sathish Kumar ),최충현 ( Chunghyeon Choi ),김천곤 ( Chungon Kim ),김선원 ( Sunwon Kim ),임재혁 ( Jaehyuk Lim ) 한국복합재료학회 2015 Composites research Vol.28 No.5

섬유체적비에 따라 복합재료의 기계적 열적 특성이 크게 달라지기 때문에, 복합재료 설계시 섬유체적비를 올바르게 측정하는 것이 매우 중요하다. 일반적으로 섬유체적비를 측정하는 여러 방법은 산화되지 않는 유리섬유나 세라믹섬유를 사용한 복합재료의 경우에는 적합하고 효율적이다. 하지만 산화현상이 있는 탄소섬유의 경우에는 산화 방법과 조건에 따라서 다른 결과를 가져오게 되며 그러므로 올바른 섬유체적비를 측정이 어렵다. 본연구에서는 Thermogravimetric analysis를 수행하여 산화되는 탄소섬유의 질량 감소량을 보정하여 탄소섬유 복합재료의 섬유체적비를 측정하였고 현미경 단면 이미지를 이용하여 그 결과를 검증하였다. Measuring fiber volume fraction properly is very important in designing composite materials because the fiber volume fraction mainly determines mechanical and thermal properties. Conventional Ignition methods are effective for ceramic fiber reinforcing composite materials. However, these methods are not proper for applying to carbon fiber reinforcing composites because of the venerable characteristic against oxidation of carbon fiber. In the research, fiber volume fraction of carbon fiber composites was obtained by a thermogravimetric analysis considering oxidation characteristic of the carbon fiber and the method was compared and verified with the results from microscopic cross section images.