• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.93-98
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• 1993

In order to discuss the mechanical properties of fiber reinforced composites with fly ash, lime, gypsum and polymer emulsion-Stylene Butadiene Rubber Latex (SBR) , experimental studies on FRC were carried out. The kinds of fiber used in FRC are PAN-dervied and Pitch-derived carbon fiver, alkali-resistance glass fiber. As a test results, the flexural strength and tougthness of fiber reinforced fly ash. lime.gypsum cement composites are remarkably increased by fiber contents ,but compressive strength of the composites are influenced by kinds of fiber more than by fiber contents. Also, addition of a polymer emulsion (SBR) to the composites decreased the bulk specific gravity, but compressive and flexural strengths, toughness of the composites are not influenced by it, are considerably improved by increasing fiber contents.

• Journal of Sensor Science and Technology
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• v.32 no.3
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• pp.159-163
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• 2023

Salt cores have attracted considerable attention for their application to the casting process of electric vehicle parts as a solution to ecological issues. However, the salt core still has low mechanical strength for use in high-pressure die casting. In this study, we investigated the improvements in the bending strength of KCl-based salt cores resulting from the use of reinforcing materials. KCl and Na₂CO₃ powders were used as matrix materials, and glass fiber and carbon fiber were used as reinforcing materials. The effects of carbon fiber and glass fiber contents on the bending strength properties were investigated. Here, we obtained a new fiber-reinforced salt core composition with improved bending strength for high-pressure die casting by adding a relatively small amount of glass fiber (0.3 wt%). The reinforced salt core indicates the improved properties, including a bending strength of 49.3 Mpa, linear shrinkage of 1.5%, water solubility rate of 16.25 g/min·m² in distilled water, and hygroscopic rate of 0.058%.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.3
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• pp.38-42
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• 2001

In the machining of glass fiber reinforced plastics(GFRP), turning has been often used. But the most of past studies have been interested in the effect of fiber orientation on tool wear. In this study, the effects of fiber contents and cutting speeds on tool wear, cutting force and surface roughness are investigated experimentally. By proper selection of cutting tool, the variables are cutting speed, fiber contents and cutting length with fixed feed rate and depth of cut. The fiber contents have major effects on coated tool wear which observed as abrasive wear type.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.34-44
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• 1996

In order to examine the accuracy of the intensity method, the fiber orientation-angle distribution of fiber-reinforced polymeric composites is measured using image processing. The fiber orientation function is calculated from the fiber orientation measured by the soft X-ray photograph. Theoretical and experimental results of fiber orientation function are compared for the composites with different fiber contents and fiber orientations. The intensity method is used for the experimental investigation and the measured fiber orientation function is compared to the calculated one. The relations between the measured and the simulated fiber orientation functions $J{\small{M}}$ and $J{\small{S}}$ respectively are identified. For the fiber length of 1.000mm and 2.000mm, it shows that $J{\small{M}}=0.83J{\small{M}}$. However. in general. the value of $J{\small{M}}$ decreases as the fiber length increases. For GFRP composites the relations between $J{\small{M}}$ and theoretical value J show that $J{\small{M}}$=0.73J for short fiber and $J{\small{M}}$=0.81J for long fiber.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.173-178
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• 2002

Fourier transform has been one of the most common tools to study the frequency characteristics of signals. With the Fourier transform alone, it is difficult to tell whether signal's frequency contents evolve in time or not. Except for a few special cases, the frequency contents of most signals encountered in the real world change with time. Time-frequency methods are developed recently to overcome the drawbacks of Fourier transform, which can represent the information of signals in time and frequency at the same time. In this study, heat damage process of a carbon fiber reinforced plastic(CFRP) and glass fiber reinforced plastic(GFRP) under monotonic tensile loading was characterized by acoustic emission. Different kinds of specimens were used to determine the characteristics of Strength and AE signals. Time-frequency analysis methods were employed for the analysis of fracture mechanism in CFRP such as matrix cracking, debonding and fiber fracture.

• Korean Journal of Materials Research
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• v.27 no.1
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• pp.39-42
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• 2017

E-glass (electrical glass) fiber is the widely used as a reinforced composite material of PCBs (printed circuit boards). However, E-glass fiber is not stable because it has a dielectric constant of 6~7. On the other hand, D-glass (dielectric glass) fiber has a low dielectric constant of 3~4.5. Thus, it is adaptable for use as a reinforcing material of PCBs. In this study, we fabricated D-glass compositions with low dielectric constant, and measured the electrical and optical properties. In the glass composition, the boron content was changed from 9 to 31 wt%. To confirm the dependence of the dielectric constant on melting properties, D-glass with 22 wt% boron was melted at $1550^{\circ}C$ and $1650^{\circ}C$ for 2hrs. The glass melted at $1650^{\circ}C$ had a lower dielectric constant than the glass melted at $1550^{\circ}C$. Therefore, the D-glass with boron of 9~31 wt% was fabricated by melting at $1650^{\circ}C$ for 2hrs, and transparent clear glass was obtained. We identified the non-crystalline nature of the glass using an XRD (x-ray diffractometer) graph. The visible light transmittance values depending on the boron contents were measured and found to be 88.6 % ~ 82.5 %. Finally, the dielectric constant of the D-glass with 31 wt% boron was found to have decreased from 4.18 to 3.93.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.41-48
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• 2000

The Compression molding process is widely used in the automotive industry to produce parts that are large, thin, light-weight, strong and stiff. Compression molded parts are formed by squeezing a glass fiber reinforced polypropylene sheet, known a glass mat thermoplastic(GMT), between two heated cavity surfaces. In this study, the anisotropic viscosity of the Unidirectional Fiber-Reinforced Plastic Composites is measured using the parallel plastometer and the composites is treated as an incompressible Newtonian fluid. The effects of molding parameter and fiber contents ratio on longitudinal/transverse viscosity are also discussed.

• Composites Research
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• v.27 no.3
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• pp.83-89
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• 2014

The purpose of this study is to improve the strength and thermal conductivity of polybutylene terephthalate (PBT) by embedding various additives. Specimens were prepared using PBT pellets embedded with glass fibers (GF) and boron nitride (BN) powders. The test results showed that tensile strength decreased, and thermal conductivity increased with increasing BN contents. with thermal shock cycles conducted, unfilled PBT showed a considerable decrease in failure strain and strength, whereas strength and thermal conductivity of glass fiber and BN particle-embedded PBT had little differeces. With increasing BN, the thermal conductivity of PBT composites was highly improved.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.339-343
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• 2012

Poly(olefin ketone) terpolymer having excellent mechanical properties was synthesized and composite materials of poly(olefin ketone) containing polyurethane/amino silane functionalized glass fibers were prepared. The compatibilities between the functionalized glass fiber and the polymer were characterized by observing the fracture surfaces of the composites using scanning electron microscopy (SEM). Mechanical properties of composites with different contents, diameters, lengths, and binders of glass fibers were also studied using universal testing machine (UTM). The introduction of suitably functionalized glass fiber into the poly(olefin ketone) produces composite materials having excellent mechanical properties and they are very promising alternative materials for the engineering plastic applications.

• Composites Research
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• v.33 no.6
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• pp.346-352
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• 2020

In mobility industries, the use of thermoplastic composites increased dynamically. In this study, the mechanical and impregnation properties of continuous glass fiber (GF)/polypropylene (PP) composite were evaluated with different GF contents. The GF/PP commingled fiber was manufactured with different GF contents and continuous GF/PP composite was manufactured using continuous compression molding process. Tensile, flexural, and impact test of specimens were evaluated with different GF contents. The fracture behavior of specimens was proved using field emission-scanning electron microscope images of fracture area and impregnation property was evaluated using dynamic mechanical analyzer and interlaminar shear strength. Finally, the GF/PP composite was the optimized mechanical and impregnation properties using 50 wt.% GF/PP commingled fiber.