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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 23, Issue 6 - Dec 2010
Volume 23, Issue 5 - Oct 2010
Volume 23, Issue 4 - Aug 2010
Volume 23, Issue 3 - Jun 2010
Volume 23, Issue 2 - Apr 2010
Volume 23, Issue 1 - Feb 2010
Selecting the target year
Prediction of Fatigue Life for Hole-notched Weave CFRP Plate
Kim, Sang-Young ; Kim, Yong-Seok ; Kwon, Hee-Whan ; Choi, Jung-Hun ; Koo, Jae-Mean ; Seok, Chang-Sung ;
Composites Research, volume 23, issue 3, 2010, Pages 1~6
DOI : 10.7234/kscm.2010.23.3.001
Recently, CFRP composite is more and more used in the various fields because of a higher specific modulus, chemical property and so on. Most products using CFRP composite are manufactured by construction of components. Various components are joined with those by bolts and pins. Holes for bolts and pins decrease strength and fatigue life of components, because those act as notch in structures. In this paper, we experimentally evaluated the fatigue life of hole-notched and unnotched weave CFRP plate. Then, we compared the two results and proposed an equation for prediction of fatigue life.
CNT and CNF reinforced carbon fiber hybrid composites by electrophoresis deposition
Choi, O-Young ; Lee, Won-Oh ; Lee, Sang-Bok ; Yi, Jin-Woo ; Kim, Jin-Bong ; Choe, Hyeon-Seong ; Byun, Joon-Hyung ;
Composites Research, volume 23, issue 3, 2010, Pages 7~12
DOI : 10.7234/kscm.2010.23.3.007
In order to increase the electrical conductivity and the mechanical properties of carbon fabric composites, multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs) were deposited on carbon fabrics by anodic and cathodic electrophoretic deposition (EPD) processes. In the cathodic EPD, carbon nano-particles and nano-sized Cu particles were simultaneously deposited on the carbon fabric, which gave a synergetic effect on the enhancement of properties as well as the degree of deposition. The hybridization of carbon nano-particles and micron-sized carbon fiber significantly improved the through-the-thickness electrical conductivity. In addition, both MWCNTs and CNFs were deposited onto the carbon fabric for multi-scale hybrid composites. Multi-scale deposition improved the through-the-thickness electrical conductivity, compared to the deposition of either MWCNTs or CNFs.
Fabrication of nano/micro hybrid compositesusing a discharge flocking device
Lee, Byung-Kon ; Lee, Hak-Gu ; Lee, Sang-Bok ; Lee, Won-Oh ; Yi, Jin-Woo ; Um, Moon-Kwang ; Kim, Byung-Sun ; Byun, Joon-Hyung ;
Composites Research, volume 23, issue 3, 2010, Pages 13~18
DOI : 10.7234/kscm.2010.23.3.013
One of the biggest challenges in the nano-field is how to effectively disperse nano-scale particles, especially CNTs, which are strongly agglomerated by intermolecular van der Waals forces. This study suggests a new method, discharge flocking, in order to disperse nano-scale particles effectively, which combines corona discharge phenomenon and a traditional electrostatic flocking process. In order to evaluate the discharge flocking process, composite specimens were fabricated by the process and RFI(resin film infusion) process, and then the mechanical and electrical properties of the specimens were measured and compared. Moreover, the evaluation of gas discharge effect on the CNTs and epoxy was performed to compare the mechanical and electrical properties of the composite specimens including the plasma treated CNTs. The experimental results showed that the electrical and mechanical properties of the specimens fabricated by the discharge flocking process were similar to those of the RFI process. In addition, plasma treated CNTs were not affected by gas discharge during the discharge flocking process.
Solution to Elasticity Problems of Structural Elements of Composite Materials
Afsar, A.M. ; Huq, N.M.L. ; Mirza, F.A. ; Song, J.I. ;
Composites Research, volume 23, issue 3, 2010, Pages 19~30
DOI : 10.7234/kscm.2010.23.3.019
The present study describes a method for analytical solution to elastic field in structural elements of general symmetric laminated composite materials. The two dimensional plane stress elasticity problems under mixed boundary conditions are reduced to the solution of a single fourth order partial differential equation, expressed in terms of a single unknown function, called displacement potential function. In addition, all the components of stress and displacement are expressed in terms of the same displacement potential function, which makes the method suitable for any boundary conditions. The method is applied to obtain analytical solutions to two particular problems of structural elements consisting of an angle-ply laminate and a cross-ply laminate, respectively. Some numerical results are presented for both the problems with reference to the glass/epoxy composite. The results are highly accurate and reliable as all the boundary conditions including those in the critical regions of supports and loads are satisfied exactly. This verifies the method as a simple and reliable one as well as capable to obtain exact analytical solution to elastic field in structural elements of composite materials under mixed and any other boundary conditions.
Variations in Electrical Conductivity of CNF/PPy Films with the Ratio of CNF and Application to a Bending Sensor
Kim, Cheol ; Zhang, Shuai ; Kim, Seon-Myeong ;
Composites Research, volume 23, issue 3, 2010, Pages 31~36
DOI : 10.7234/kscm.2010.23.3.031
A new material, carbon-nanofiber/polypyrrole (CNF/PPy) composite films, with different CNF weight ratios were fabricated electrochemically. Compared to the fabrication process based on simple physical mixing, the flexibility of the new film has been improved much better than the previous similar material. Pure PPy films were also fabricated by the new electrochemical process for the comparison of difference. Several SEM images were taken at two locations (electrode-side and solution-side) and at the cross section of the samples. Electrical conductivity of the composite films was measured by the four-probe method. The conductivity of the pure PPy film 0.013cm thick was 79.33S/cm. The CNF/PPy composite film with 5% CNF showed a conductivity of 93S/cm. One with 10% CNF showed a conductivity of 126 S/cm. The conductivity of PPy improves, as the CNF weight ratio increases. The good conductivity of CNF/PPy composites makes them a candidate for a small bending actuator. A bending sensor consists of PPy and PVDF, which can be operated in the air, was designed and the bending deflection was calculated using FEM.
Test Method to Evaluate the Fiber Material Properties of Filament Wound Composite Pressure Vessel
Hwang, Tae-Kyung ; Park, Jae-Beom ; Kim, Hyoung-Geun ;
Composites Research, volume 23, issue 3, 2010, Pages 37~42
DOI : 10.7234/kscm.2010.23.3.037
The fiber material properties, elastic constant and strength, are the most important factors among the various material properties for the design of composite pressure vessel, because of it`s dominant influence on the performance of composite pressure vessel. That is, the deformation and burst pressure of pressure vessel highly affected by the fiber material properties. Therefore, the establishment of test method for exact fiber material properties is a priority item to design a composite pressure vessel. However, the fiber material properties in filament wound pressure vessel is very sensitive on various processing variables (equipment, operator and environmental condition etc..) and size effect, so that it isn`t possible to measure exact fiber material properties from existing test methods. The hydro-burst test with full scale pressure vessel is a best method to obtain fiber material properties, but it requires a enormous cost. Thus, this paper suggests a newly developed test method, hoop ring test, that is capable of pressure testing with ring specimens extracted from real composite pressure vessel. The fiber material properties from hoop ring test method showed good agreement with the results of hydro-burst test with full scale composite pressure vessels.
Studies on the Melting Characterization of Basalt and its Continuous Fiber Spinning
Park, Hye-Jung ; Park, Sun-Min ; Lee, Jae-Won ; Roh, Gwang-Chul ; Kim, Jae-Keun ;
Composites Research, volume 23, issue 3, 2010, Pages 43~49
DOI : 10.7234/kscm.2010.23.3.043
Basaltic fiber was prepared by continuous spinning process from Jeju Pyosun raw basalt materials. First, for confirming the melting characterization of basalt, basalt raw material put into Pt crucible and melted up to
then quenched by dropping it into water. After quenching, the optimum fiber spinning conditions were investigated by measurement and analysis of XRD, TMA, high temperature viscosity, high temperature conductivity and high temperature microscope. The optimum spinning temperature and viscosity for preparation of continuous filament fiber were
, respectively. Properties of prepared spinning fiber were confirmed by tensile strength, FE-SEM, heat resisting test and others. The tensile strength of fiber prepared by spinning conditions of the bushing temperature
and winder speed 4600rpm was 3660MPa.
Fluorescence Characteristic Analysis for Fiber Detection in Sectional Image of Fiber Reinforced Cementitious Composite
Lee, Bang-Yeon ; Park, Jun-Hyung ; Kim, Yun-Yong ;
Composites Research, volume 23, issue 3, 2010, Pages 50~57
DOI : 10.7234/kscm.2010.23.3.050
It is important to detect fibers in the sectional image of fiber reinforced cementitious composites (FRCC), since the fiber distribution is a crucial factor to predict or evaluate the mechanical performance of FRCC. In this paper, we investigated the fluorescence characteristics of Polyvinyl Alcohol (PVA) fibers, Polyethylene Terephthalate (PET) fibers, Polyethylene (PE) fibers, and Polypropylene (PP) fibers used in Engineered Cementitious Composites (ECC), which is a special kind of FRCC that incorporates synthetic fibers and exhibits extremely ductile behavior in uniaxial tension, to detect each fiber according to its type. Furthermore, optimum excitation and emission wavelengths were proposed on the basis of maximum difference of Relative Fluorescence Intensity (RFI) between two types of fibers used in the hybrid ECC. Optimum threshold values to discriminate two types of fibers using statistical tools were also proposed. Finally, images of four types of fibers obtained using a fluorescence microscope are compared.
Dispersion and property evaluation of nanocomposites by aspect ratio of MWCNT
Jang, Jung-Hoon ; Yi, Jin-Woo ; Lee, Won-Oh ; Lee, Hak-Gu ; Um, Moon-Kwang ; Kim, Jin-Bong ; Byun, Joon-Hyung ;
Composites Research, volume 23, issue 3, 2010, Pages 58~63
DOI : 10.7234/kscm.2010.23.3.058
Tensile and flexural properties and electrical conductivity of MWCNT/epoxy composites with different aspect ratios of MWCNTs were compared. The MWCNT/epoxy mixtures were prepared by mechanical dispersion methods using a homomixer and a three-roll mill, and then composite samples were fabricated by compression molding process. The fractured surfaces of the samples were observed by SEM in order to evaluate the degree of dispersion of MWCNTs. The addition of MWCNTs into epoxy resin improved its tensile strength by 7.0% while its flexural strength increased slightly as compared with the one without MWCNTs. In the case of MWCNTs having highest aspect ratio, the mechanical properties of the composites were decreased. When the contents of CM-95 MWCNTs were varied, maximum of tensile and flexural strengths occurred at 1wt% and 0.5wt%, respectively. From the higher contents than these, tensile and flexural strengths of the composites decreased. Electrical conductivities of in-plane and thought-the-thickness directions of MWCNT/epoxy composites were measured using a two-point probe method. They increased with the increase of the aspect ratios and concentrations of MWCNTs in the epoxy matrix.
Investigation of the Strain Rate Effects of EPS Foam
Kang, Woo-Jong ; Cheon, Seoung-Sik ; Lee, In-Hyeok ; Choi, Seon-Ung ; Min, Je-Hong ; Lee, Sang-Hyeok ; Bae, Bong-Kook ;
Composites Research, volume 23, issue 3, 2010, Pages 64~68
DOI : 10.7234/kscm.2010.23.3.064
Expanded polystyrene(EPS) foams are often used in packaging to protect electrical appliances from impact loads. The energy absorbing performances of the EPS foams depend on several parameters such as density, microstructure and strain rate. Thus, the effects of the parameters on the strength of the EPS foams need to be investigated for an optimized packaging design by FEM. In this study, various EPS foams which have different densities were quasi-statically and dynamically loaded in order to obtain the stress-strain curves. EPS foams of various densities from 18.5 to 37.0kg/m3 were considered in the experiments. A drop-mass type apparatus was developed for the intermediate strain rate tests up to several hundreds/second. It was found from the experimental results that the strength of the EPS foams increase about 170% as the strain rate increases from 0.06/s to 60/s. Experimental results also showed that the strain rate sensitivity increases as the strain increases.