• Magazine of RCR
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• v.17 no.1
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• pp.10-14
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• 2022

• Fibers and Polymers
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• v.2 no.1
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• pp.163-172
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• 2001

To determine three-dimensional fiber orientation states in injection-molded short fiber composites a CLSM (Confocal Laser Scanning Microscope) is used. Since the CLSM optically sections the composites, more than two cross-sections either on or below the surface of the composite can be obtained. Three dimensional fiber orientation states can be determined with geometric parameters of fibers on two parallel cross-sections. For experiment, carbon fiber reinforced polystyrene is examined by the CLSM. Geometric parameters of fibers are measured by image analysis. In order to compactly describe fiber orientation states, orientation tensors are used. Orientation tensors are determined at different positions of the prepared specimen. Three dimensional orientation states are obtained without the difficulty in determining the out-of-plane angles by utilizing images on two parallel planes acquired by the CLSM. Orientation states are different at different positions and show the shell-core structure along the thickness of the specimen.

• Computers and Concrete
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• v.15 no.1
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• pp.21-35
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• 2015

The objective of this study is to examine the effect of carbon fiber reinforced polymer (CFRP) on the shear strengths of deep beams with web openings. A total of 18 high-strength concrete deep beams with web openings were tested. Twelve were externally wrapped with four layers of CFRP, six of them strengthened in the horizontal direction and the others in the vertical direction. The parameters of the configuration of CFRP, the sizes of the openings and the locations of the openings were covered in this study. The test results indicates the shear strengths of deep beams with openings sized $60{\times}40mm$ were about 16% higher than that with openings sized $68{\times}68mm$. For deep beams with openings sized $60{\times}40mm$, the lower the locations of openings the higher the shear strengths were. The test results also indicate the shear strengths of deep beams with web openings strengthened by CFRP wrapped in the vertical direction can be enhanced by about 10%. However, the shear strengths of deep beams with web openings strengthened by CFRP wrapped in the horizontal direction can only be enhanced by about 6%. The shear strengths of deep beam, with different size and location of web openings and strengthened by different configuration of CFRP can be reasonably predicted by the empirical formulas of Kong and Sharp.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.439-445
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• 2016

Carbon fiber reinforced plastic (CFRP) composites have been widely used due to their great strength, stiffness and light weight. However, due to its anisotropy and inhomogeneous properties the machining process of CFRP composites is typically more complex than that of regular metals. Since there are many defects, such as delamination and tool wear during the machining process of CFRP composites, the optimization of this process is essential in improving the productivity. In this study, orthogonal machining of CFRP composites was performed to identify the machining characteristics of these materials. In addition, an experimental observation of delamination was investigated through the use of scanning electron microscopy (SEM). In these experiments, the cutting forces were measured and analyzed to determine the difference between machining of CFRP composites and metals. The comparison between the numerical models and experimental results was performed in terms of the maximum cutting forces.

• Journal of Power System Engineering
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• v.18 no.4
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• pp.78-84
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• 2014

The estimation of deformation and strain for the twill-weave carbon fiber reinforced plastic composite(CFRP) during the test with a digital image correlation system were implemented experimentally. The carbon fiber reinforced plastic composites have been developed as the edge technology materials. The plain, twill and satin weave types are commonly used for the CFRP composites. Thus, it is essential to find the deformation characteristics for those types of CFRP more easily. Especially the DIC method can express the visual strain distributions at the full range of the interested areas in the structures. In this study, the mechanical properties of twill-weave CFRP composite and the variation of strains in a full field of the specimen were estimated. The experiments were performed under a tensile loading and 3-point bending test with strain gages. Futhermore the DIC deformation results were estimated for the comparison. The results showed the deformation and strain contours visually well in all region of the interested areas and so usefulness for the safety control of the structures.

• Journal of the Korean Society of Safety
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• v.29 no.5
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• pp.7-14
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• 2014

This study aimed to develop members with the optimum impact characteristics to ensure a protected space for passengers in the case of automobile collisions. Accordingly, these members were fabricated to provide sufficient rigidity and safety to the passenger room structure and to absorb large amounts of energy during collision. In particular, CFRP members were fabricated with different section shapes such as square and single- and double-hat shapes. Next, their impact collapse characteristics and collapse modes were quantitatively analyzed according to the changes in section shapes and stacking angles. This analysis was performed to obtain design data that can be applied in the development of optimum lightweight members for automobiles.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.2945-2951
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• 2000

Because of the inherent flexibility in their design for improved material properties, composites have wide applications in aerospace vehicles and automobiles. The purpose of this study is to investigate the energy absorption characteristics of CFRP( Carbon Fiber Reinforced Plastics); tubes on static and impact tests. Static compression tests have been carried out using the static testing machine(Shin-gang buckling testing machine)and impact compression tests have been carried out using the vertival crushing testing machine. When such tubes were subjected to crushing loads, the response is complex and depends on the interaction between the different mechanisms that control the crushing process. The collapse characteristics and energy absorption were examined. Trigger and interlaminar number affect energy absorption capability of CFRP tubes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1104-1112
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• 2014

We present a design of the deployable lightweight antenna to be used in the satellite satisfying the required performance of the onboard sensor. The analysis is performed on the SAR antenna requirements, deploying techniques including material selection, and the characterization of deployable antenna with central disk. The performance of the solid deployable antennas and the mesh antennas are simulated, and the CFRP(Carbon Fiber Reinforced Plastics) samples are manufactured and tested. It is confirmed that the deployable antennas with central disk can meet the required performance by using deploying panels or mesh.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.83-88
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• 2017

Recently, the use of advanced materials with light weight significantly increases because of global regulation on CO2 emission. Especially, CFRP (carbon fiber reinforced plastics) one of the most promising advanced materials. Since CFRP has pretty higher strength per unit weight than steel, it is one of most popular materials in aviation industry and its application to automobile rises sharply. Especially, one of the frequent machining processes for CFRP is drilling to make a hole, however, CFRP drilling has troublesome limitations in hole quality and productivity induced due to delamination, splintering and severe tool wear. Particularly, cutting loads increase caused by tool wear makes delamination and splintering even severer. Therefore, tool wear monitoring or reduction in CFRP drilling must be considered seriously. In this study, we measured thrust force, flank wear, and tool surface temperature in drilling using various tools with different sizes and materials. Consequently, it was presented the effects of tool properties on drilled hole quality, thrust force and tool surface temperature.

• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.58-65
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• 2018

The dynamic characteristics of the deployable composite parabolic reflector with several panels were numerically and experimentally investigated. The deployment mechanism is designed to efficiently fit in a small volume. The parameters guiding the deployment are determined by considering; the number of panels, folding/twisting angles, and the driving forces of actuating devices. The panels are fabricated using carbon fiber reinforced plastics (CFRPs). The zero-gravity simulator is manufactured for the unfolding test. The deployment behaviors of the reflector are finally observed.