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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
The Korean Society for Composite Materials
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Volume & Issues
Volume 28, Issue 6 - Dec 2015
Volume 28, Issue 5 - Oct 2015
Volume 28, Issue 4 - Aug 2015
Volume 28, Issue 3 - Jun 2015
Volume 28, Issue 2 - Apr 2015
Volume 28, Issue 1 - Feb 2015
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Characterization of FeCo Magnetic Metal Hollow Fiber/EPDM Composites for Electromagnetic Interference Shielding
Choi, Jae Ryung ; Jung, Byung Mun ; Choi, U Hyeok ; Cho, Seung Chan ; Park, Ka Hyun ; Kim, Won-jung ; Lee, Sang-Kwan ; Lee, Sang Bok ;
Composites Research, volume 28, issue 6, 2015, Pages 333~339
DOI : 10.7234/composres.2015.28.6.333
Electromagnetic interference shielding composite with low density (
) was fabricated using electroless plated FeCo magnetic metal hollow fibers and ethylene propylene diene monomer (EPDM) polymer. Aspect ratio of the fibers were controlled and their hollow structure was obtained by heat treatment process. The FeCo hollow fibers were then mixed with EPDM to manufacture the composite. The higher aspect ratio of the magnetic metal hollow fibers resulted in high electromagnetic interference shielding effectiveness (30 dB) of the composite due to its low sheet resistance (30 ohm/sq). The enhanced electromagnetic interference shielding effectiveness was mainly attributed to the formation of conducting network over the percolation threshold by high aspect ratio of fibers as well as an increase of the reflection loss by impedance mismatch owing to low sheet resistance, absorption loss, and multiple internal reflections loss.
Experimental and Phenomenological Modeling Studies on Variation of Fiber Volume Fraction during Resin Impregnation in VARTM
Kim, Shin O ; Seong, Dong Gi ; Um, Moon Kwang ; Choi, Jin Ho ;
Composites Research, volume 28, issue 6, 2015, Pages 340~347
DOI : 10.7234/composres.2015.28.6.340
As resin impregnates through the fiber preform in vacuum assisted resin transfer molding process, the volume of fibers is changed by expansion of fiber mat according to filling time. It causes not only the change in dimension but also the decrease of mechanical properties of the composite product. Moreover, it results in the economic loss by increase of the used amount of resin especially in the large product such as wind turbine blade. In this study, the ways to control fiber volume fraction were investigated by both the experimental and theoretical analyses on the expansion of fiber preform as the preform was impregnated by resin in the VARTM process. Two kinds of swelling stage were observed as flow front progressed, which was analyzed by comparing the experimental and simulation results. The process parameters are expected to be optimized by investigating the swelling behavior of fiber preform in the manufacturing process of the composite product.
Evaluation of Dispersivity and Resistance of the Adhesive Joint According to Dispersion Methods of CNT
Lee, Bong-Nam ; Kim, Cheol-Hwan ; Kweon, Jin-Hwe ; Choi, Jin-Ho ;
Composites Research, volume 28, issue 6, 2015, Pages 348~355
DOI : 10.7234/composres.2015.28.6.348
NDT (Non Destructive Test) of the adhesive joints is very important because their strengths have greatly affected by the worker's skill and environmental condition. Recently, the electric impedance method in which 1-2 wt% CNT was dispersed in the adhesive and the electric resistance of the adhesive joint was measured was suggested for the defect detection of the adhesive joint. The uniform dispersion of CNT in the electric impedance method is very important to make a constant electric resistance of the adhesive joint and the accuracy of defect detection depends on the uniform dispersion. In this paper, the adhesive joints in which CNT was dispersed in the adhesive by the four dispersion methods were made and their electric resistance were measured. The pre-process and evaporation process of CNT using the ultrasonic method and agitation method was used and the effective dispersion method was suggested. Also, the criteria to evaluate the dispersivity was proposed.
Fracture Behaviour Analysis of the Crack at the Specimen with the Type of Mode I Composed of the Bonded Carbon Fiber Reinforced Plastic
Lee, Jung-Ho ; Cho, Jae-Ung ; Cheon, Seong-Sik ; Kook, Jeong Han ;
Composites Research, volume 28, issue 6, 2015, Pages 356~360
DOI : 10.7234/composres.2015.28.6.356
In this paper, the carbon fiber reinforced plastic is processed as the double cantilever beam in order to estimate the fracture behavior of composite and is carried out with the static analysis as the mode I. The specimen sizes are 25 mm, 30 mm, 35 mm and 40 mm. And the material property is used with carbon. As the analysis result of mode I, the adhesive part is detached latest by the small force at the specimen thickness of 25 mm. The largest force is happened at the specimen thickness of 40 mm. The defection of the adhesive interface is shown slowest at the displacement of 9.75 mm at the specimen thickness of 25 mm. And the defection is shown quickest at the displacement of 7.82 mm at the specimen thickness of 40 mm. This defection is due to the fracture of specimen. The result of this study on the defection of the adhesive interface and the reaction force due to this defection is thought to be contributed to the safe structural design of the carbon fiber reinforced plastic.
Influence of MWCNTs on Fracture Toughness of MWCNTs/Nickel-Pitch Fiber/Epoxy Composites
Yim, Yoon-Ji ; Park, Soo-Jin ;
Composites Research, volume 28, issue 6, 2015, Pages 361~365
DOI : 10.7234/composres.2015.28.6.361
The influence of MWCNTs on fracture toughness properties of MWCNTs/Nickel-Pitch Fibers/epoxy composites (MWCNTs/Ni-PFs/epoxy) was investigated according to MWCNTs content. Nickel-Pitch-based carbon fibers (Ni-PFs) were prepared by electroless nickel-plating. The surface properties of Ni-PFs were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS). The fracture toughness of MWCNTs/Ni-PFs/epoxy was assessed by critical stress intensity factor (
) and critical strain energy release rate (
). From the results, it was found that the fracture toughness properties of MWCNTs/Ni-PFs/epoxy were enhanced with increasing MWCNTs content, whereas the value decreased above 5 wt.%. MWCNTs content. This was probably considered that the MWCNTs entangled with each other in epoxy due to an excess of MWCNTs.
High Temperature Thermo-mechanical Properties of HfC Reinforced Tungsten Matrix Composites
Umer, Malik Adeel ; Lee, Dong Ju ; Ryu, Ho Jin ; Hong, Soon Hyung ;
Composites Research, volume 28, issue 6, 2015, Pages 366~371
DOI : 10.7234/composres.2015.28.6.366
In order to improve the mechanical properties of tungsten at room and elevated temperature, hafnium carbide (HfC) reinforced tungsten matrix composites were prepared using the spark plasma sintering technique. The effect of HfC content on the compressive strength and flexural strength of the tungsten composites was investigated. Mechanical properties of the composites were also measured at elevated temperatures and their trends, with varying reinforcement volume fraction, were studied. The effect of reinforcement fraction on the thermal properties of the composites was investigated. The thermal conductivity and diffusivity of the composites decreased with increasing temperature and reinforcement volume fraction. An inherently low thermal conductivity of the reinforcement as well as interfacial losses was responsible for lower values of thermal conductivity of the composites. Values of coefficient of thermal expansion of the composites were observed to increase with HfC volume fraction.
Study on Analysis of RTM Process to Manufacture Bogie Frame Skin Depending on Thickness
Kim, Moosun ; Kim, Jung-Seok ; Kim, Seung Mo ;
Composites Research, volume 28, issue 6, 2015, Pages 372~377
DOI : 10.7234/composres.2015.28.6.372
In this study, we analyzed process numerically when a bogie frame skin is manufactured by applying resin transfer molding process using composite material instead of steel. Processing time was compared based on the various thickness of bogie frame skin and the weight variation of a skin was also considered. As a result, RTM processing time decreases and the weight of a bogie reduces as the thickness of frame skin increases with the assumption that fiber volume is constant inside the skin. By considering these results as the information to estimate the production cost, trade-off between two fields, processing time and structural properties, can be performed in design optimization to produce bogie frame.
Comparison between Wire Rope and CFRP UD on Bending Analysis
Park, Sung-Min ; Shin, Dong-Woo ; Kwon, Il-Jun ; Yoo, Sung-Hun ; Moon, Wan-Kee ;
Composites Research, volume 28, issue 6, 2015, Pages 378~382
DOI : 10.7234/composres.2015.28.6.378
With increasing population density and high-rise expansion of buildings in recent years, elevators have become to play a pivotal role in our everyday lives as most people take an elevator several times even in a day. The elevator penetration and distribution rates in Korea have increased dramatically every year, and the emergence of skyscrapers leads to accelerating the development of elevator industry. Carbon-fiber-reinforced plastics (CFRPs) exhibit better mechanical and thermal properties than steel suitable for uses as elevator wire ropes. In this paper, in order to analyze the properties of CFRPs, the tensile strength of unidirectional (UD) CFRP wire ropes was characterized and finite element analysis was conducted for bending simulation. Simulation results were compared.
State Observer Based Modeling of Voltage Generation Characteristic of Ionic Polymer Metal Composite
Lee, Hyung-Ki ; Park, Kiwon ; Kim, Myungsoo ;
Composites Research, volume 28, issue 6, 2015, Pages 383~388
DOI : 10.7234/composres.2015.28.6.383
Ionic Polymer-Metal Composite (IPMC) consisting of soft membrane plated by platinum electrode layers on both surfaces generates electric energy when subjected to various mechanical stimuli. The paper proposes a circuit model that describes the physical composition of IPMC to predict the voltage generation characteristic corresponding to bending motion. The parameter values in the model are identified to minimize the RMS error between the real and simulated outputs. Following the design of IPMC circuit model, the state observer of the model is designed by using pole placement technique which improves the model accuracy. State observer design technique is also applied to find the inverse model which estimates the input bending angles from the output voltage data. The results show that the inverse model estimates input bending angles fairly well enough for the further applications of IPMC not only as an energy harvester but also as a bending sensor.
Effect of Graphite Intercalation Compound on the Sound Absorption Coefficient and Sound Transmission Loss of Epoxy Composites
Lee, Byung-Chan ; Park, Gyu-Dae ; Choi, Sung-Kyu ; Kim, Sung-Ryong ;
Composites Research, volume 28, issue 6, 2015, Pages 389~394
DOI : 10.7234/composres.2015.28.6.389
The sound absorption coefficient and sound transmission loss of graphite intercalation compound (GIC) included epoxy composites were investigated. Epoxy resin was infused into the expanded GIC and the impedance tube method was employed to measure the sound absorption coefficient and sound transmission loss. Scanning electron microscopy photographs showed uniform distribution of the GIC in the epoxy matrix. The surface density of epoxy/GIC (20 wt%) composites decreased about 56% compared to that of pure epoxy. The sound absorption coefficient of composites increased about 3 times at the frequency range of 500~1000 Hz compared to the pure epoxy. The sound transmission loss of composites decreased with increasing the GIC content and it is attributed to the increase of pores in the composites.
Thermal Stability of Grubbs' Catalyst and Its Reactivity with Self-healing Agents
Yoon, Sung Ho ; Shi, Ya Long ; Feng, Jun ; Jang, Se Yong ;
Composites Research, volume 28, issue 6, 2015, Pages 395~401
DOI : 10.7234/composres.2015.28.6.395
This study investigated the thermal stability of Grubbs' catalyst and its reactivity with self-healing agents for self-healing damage repair. Four types of Grubbs' catalyst supplied by manufacturers were considered and each catalyst was tested in as-received and grinded conditions. Four types of self-healing agents were prepared by varying the mixing ratio of dicyclopentadiene (DCPD) and 5-ethylidene-2-norbonene (ENB). Heat flows as a function of temperature were measured through a differential scanning calorimetry (DSC) to determine the thermal stability of catalysts. Reaction heats of self-healing agents with the catalyst were measured to evaluate the reactivity of the catalyst. For this evaluation, Fluka Chemika Grubbs' catalyst was used based on the maximum temperature and the time to reach the maximum temperature. According to the results, catalysts had different shapes depending on the manufacturer and the results showed that the smaller the size of the catalyst the higher the reactivity with self-healing agents. As the ENB ratio in self-healing agents increased, the maximum temperature increased, and the time to reach the maximum temperature decreased. As the amount of the catalyst increased, the maximum temperature increased, and the time to reach the maximum temperature decreased. Considering the thermal stability of the catalyst and its reactivity with the self-healing agent, combination of 0.5 wt% catalyst and the D3E1 self-healing agent was optimal for self-healing damage repair. Finally, as the thermal decomposition may occur depending on the environmental temperature, the catalyst must not be exposed to temperature higher than that is necessary to maintain the thermal stability of the catalyst.
Establishment of Aerospace Composite Materials Data Center for Qualification
Lee, Ho-Sung ; Rhee, Seung Yun ; Yoon, Jong-Hoon ; Yoo, Joon-Tae ; Min, Kyung Ju ;
Composites Research, volume 28, issue 6, 2015, Pages 402~407
DOI : 10.7234/composres.2015.28.6.402
It is well known that the polymer matrix composite materials have good specific strength, making them appropriate for use in transport vehicle. Since the property of composite materials can be obtained only after manufacturing parts, the property depends on greatly on the fabrication process, which is different from metallic system. Therefore, in order to use composite materials for aircraft, the certifying agency requires a robust database with extensive tests and proof of the process unlike metals. Recently developed material qualification methodology by NCAMP (National Center for Advanced Materials Performance) has been accepted by FAA and EASA and can be applied to type certificate reducing time and cost of developing a composite materials database for aircraft application. This paper summarizes a study to establish the composite materials database to apply the NCAMP methodology to composite materials characterization for composite aircraft and to provide the effective materials database through Aerospace Composite Materials Data Center to be approved by Korea Civil Aviation Certification Agency.