• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.799-804
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• 2011

CFRP(Carbon Fiber Reinforced Plastics) has been used many industries aerospace, automobile, medical device and building material industries, etc. Because it is lighter than other metals and has good properties, such as rigidity, strength and wear. CFRP may be cured integrity. However, it needs postprocessing similar to drilling or endmilling for shape cutting and combination of various material. In this paper, tool dynamometer and accelerometer used to signal analysis for machining properties under various cutting conditions and tool shape changes. In addition, microscope used to verify the machined CFRP surface. As the results, it was found that the cutting force and the vibration were decreased in the increasing of cutting edge (2-flute < 4-flute < composite tool), and the good machined surface can be obtained in this experiments.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.214-215
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• 2017

Extreme loads such as impact and explosion have higher strain rate than static loading condition. Therefore, it is necessary to evaluate mechanical properties at high strain rate in order to apply fiber reinforced cement composites to ensure safety performance against impact and explosion. In this study, the compressive properties of fiber reinforced cement composites by strain rate were evaluated.

• Composites Research
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• v.24 no.3
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• pp.12-16
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• 2011

High strain rate tensile tests were performed to measure the strain rate sensitivity of fiber reinforced composite material. The composite material was developed for the light weight design of an automotive FEM(front end module) carrier. Standard specimens for quasi-static tests of fiber reinforced composites can be found in ASTM D3039. However, in case of high strain rate tests, it was hard to find standard specimen shapes. In this study, three kinds of tensile specimens designed based on ASTM D638 were investigated to determined the adequate gauge width of tensile specimen for fiber reinforced composite. A drop tower type of high speed tensile apparatus was developed for strain rates of about 15/s and 100/s. Gauge width of 6mm, 8mm and 10mm were investigated. Test results showed the specimen of 8mm width was adequate for the high strain rate tensile tests of fiber reinforced composite. It was found the strength of the composite material increased as the strain rate increased.

• Composites Research
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• v.27 no.3
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• pp.96-102
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• 2014

In this study, we fabricated jute fiber reinforced polylactic acid (PLA) composite in the form of sandwich panel structure which includes core foam of chopped jute fiber reinforced PLA and outer skin layer of continuous glass fiber reinforced PLA. Flexural properties of the composite were assessed for different jute fiber weight fractions. Density of the core foam ranged from 0.31 to 0.67 $g/cm^3$ and void content fraction 0.51 to 0.71. The maximum flexural strength was 92.7 MPa at 12.5 wt.% of jute fiber content, and the maximum flexural modulus was 7.58 GPa at 30.0 wt.%. Cost analysis was also conducted. The cost to enhance the flexural strength of the applied structure was estimated to be $0.010USD/m^3/MPa$ for 12.5 wt.% fiber content.

• Composites Research
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• v.36 no.1
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• pp.37-41
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• 2023

The treated water inside the ballast electrolytic cell creates a highly alkaline atmosphere due to hydroxide generated at the DSA(Dimension Stable Anode) electrode during electrolysis. In this study, a composite material that can replace the weakness of the PE-coated steel pipe used in the existing ballast pipe was prepared. The test samples are BRE(Basalt fiber reinforced epoxy), BRP(Basalt fiber reinforced unsaturated polyester), GRE(Glass fiber reinforced epoxy), and GRP(Glass fiber reinforced unsaturated polyester). And then it was immersed in NaOH for 720 hours. The friction test of each specimen was conducted. The Friction coefficient analysis according to material friction depth and interfacial adhesion behavior between resin and fiber were analyzed. As a result, the mechanism of interfacial separation between resin and fiber could be analyzed. In the case of the unsaturated polyester resin with low interfacial bonding strength the longer the immersion time in the alkaline solution, the faster the internal deterioration caused by the deterioration that started from the surface, resulting in a decrease in the friction coefficient. It is hoped that this study will help to understand the degradation behavior of composite materials immersed in various chemical solutions such as NaOH, acid, and sodium hypochlorite in the future.

• 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.

• Magazine of the Korean Society of Agricultural Engineers
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• v.29 no.4
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• pp.124-131
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• 1987

The aims of this study was to determine the mechanical properties of steel-fiber reinforced concrete under direct tensile loading, and also to insestigate the mechanism fiber reinforcement in order to improve the possible applications of steel-fiber reinforced concrete. In this study the major variables of experimental investigation were fiber conntents, and the lengths and diameters of fibers. The major results obtained are summarized as follows : 1. The strength, elastic modulus and energy absorption capability of steel-fiber reinforced concrete under direct tensile loading were improved as increasing of fiber contents. 2. The direct tensile strength of steel-fiber reinforced concrete was not influenced by the lengths of fiber, but was decreased as increasing of fiber diameters. 3. The direct tensile strength of steel-fiber reinforced concrete was not influenced by the fiber aspect-ratio, but this was because the fiber contents were below the critical value of fiber content. 4. The correlation of direct tensile strength and combined parameter, Vf l/d, was not good. 5. Mutiple cracking and post-crack resistance were investigated at stress-strain curves in direct tensile test. 6. The effect of fiber reinforcement can be influenced by fiber orientation and the bond strength between fiber and matrix. 7. The improvement of mechanical properties of steel-fiber reinforced concrete under direct tensile loading can be theoretically explained by the concept of composite materials.

• International Journal of Safety
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• v.3 no.1
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• pp.1-5
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• 2004

This study discusses frequency analysis based on autoregressive (AR) time series model, and the characterization of surface quality in orthogonal cutting of a fiber-matrix composite materials. A sparsely distributed idealized composite material, namely a glass reinforced polyester (GFRP) was used as workpiece. Analysis method employs a force sensor and the signals from the sensor are processed using AR time series model. The experimental correlations between the fiber pull-out and AR model coefficients are then established.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.149-153
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• 1999

During a hemisphere-type compression molding, the wrinkles are caused by complex stress condition. It is very important to clarify the degree of wrinkles in order to have good products. In this paper, the effects of numbers of needling and initial area on the degree of wrinkles are studied. the degree of wrinkle is expressed as nonhomogeneity.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.241-248
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• 2012

This paper presents a reinforced concrete composite column method in order to improve seismic performance of reinforced concrete column specimens by selectively applying steel fiber-reinforced mortars at the column plastic hinge region. In order to evaluate seismic improvement of the newly developed column method, a series of cyclic load test of column specimens under a constant axial load was investigated by manufacturing three specimens, two reinforced concrete composite columns by applying steel fiber-reinforced mortars at the column plastic hinge region and one conventional reinforced concrete column. Both concrete and steel fiber-reinforced mortar was cast-in placed type. From cyclic load test, it was found that the newly developed steel fiber-reinforced columns showed improved seismic performances than conventional reinforced concrete column in controlling bending and shear cracks as well as improving seismic lateral load-carrying capacities and lateral deformation capacities.