• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.133-138
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• 2017

Recently, CFRP composites are widely used as lightweight materials have with excellent mechanical properties and can beare widely used in various fields. In general, thermosetting resins are used for CFRP. However, in recent years, studies have been carried out using thermoplastic resins have been actively carried out to overcome the disadvantages of thermosetting resins. The LFT-D system is a molding method in which a fiber is directly cut to a the desired length while being impregnated with a thermoplastic resin to produce a compound and that is then press-molding molded to form the product. In this paper, before the production of the trailing arm, the compression molding analysis was carried out in order to grasp the problems that may occur during production. Through cCompression molding analysis was applied to calculate of the minimum press pressure and to compare and analysis analyze the molding conditions characteristic required to formfor forming the trailing arm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.80-85
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• 2016

Carbon fiber-reinforced composite materials have been widely used in various industrial fields, but there are limits to increasing their strength and stiffness, because of the short-length fibers that are impregnated in them. In this study, a lab-scale small extruder system was developed with the capability to perform the carbon fiber impregnation and extrusion process in order to evaluate the properties of long-length carbon fiber reinforced thermoplastic composite materials molded by the LFT-D method. Specimens were made with the small extruder to press-mold long-length carbon fiber composite materials and evaluate their material properties. As a result, it was found that the carbon fiber length, press load and carbon fiber contents have a considerable influence on the strength and stiffness. Additional studies on such factors as the mixing screw design and coating of the carbon fiber are needed in order to improve the mechanical properties of carbon fiber composite materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1982-1987
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• 2011

In this study, we proposed a new method that can estimate viscosity curves of unknown samples or high viscous resins like LFT(Long Fiber Thermoplastics). First, we built the system that could detect the pressure of melt during filling the cavity in a mold. It consists of both pressure sensors which are installed in a mold and the Kit which can convert analog signal to digital signal. The kit measures the melt pressure in mold cavity. We could also simulate the cavity pressure during filling process with commercialized CAE softwares(ex, Moldflow). If the viscosity data in CAE Database were correct, the simulated pressure profile coincided with the measured one. According to our proposed algorithm, we obtained correct viscosity data by iterating the process of comparing the simulated profile with the measured one until both coincided each other. In order to verify this algorithm, we selected well-defined PP resin and concluded that the experimental profile comply with the CAE profile. We could also estimate the optimized viscosity curves for PP-LFT by applying our method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.877-887
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• 2015

We have proposed a new method for estimating the viscosity of the composite. In this paper, we have developed a device for measuring the injection mold cavity pressure. This makes it possible to verify the accuracy of the viscosity in CAE D/B in real time by measuring the melt pressure in the mold, and comparing this with the simulated pressure from the CAE analysis. Materials used in this study is a PP(Polypropylene), PP/LGF30%(Polypropylene/long glass fiber 50% composite) and PA66/LGF50%(Polyamide 6,6/long glass fiber 50% composite). The viscosity data for PP and PP long fiber composite have already been built, but the one for PA66 long-fiber composite does not exist because it is a newly developed material. Thus we obtained the viscosity curve of PA66/LGF50% by this system. Then, the viscosity curves from conventional viscometer were also compared with the viscosity obtained by the our method. And, we proved the accuracy of the CAE data of PP. In case of PP/LGF50% which is highly viscous and complex material, we improved the existing CAE data.because there was a difference between the measuring data and the CAE data.