• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.284-287
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• 2002

During resin transfer molding(RTM) process, in case of thick parts, resin flow and void formation should be modeled three dimensionally even though for parts of small thickness, resin flow and void formation can be modeled two dimensionally. In this study, numerical simulations of three dimensional mold filling and void formation during RTM process.

• Advanced Composite Materials
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• 제16권3호
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• pp.207-221
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• 2007

The filling process of resin injection/compression molding (I/CM) can be divided into injection and compression phases. During the resin injection the mold is kept only partially closed and thus a gap is present between the reinforcements and the upper mold. The gap results in preferential flow path. After the gap is filled with the resin, the compression action initiates and forces the resin to penetrate into the fiber preform. In the present study, the resin flow in the gap is simplified by using the Stokes approximation, while Darcy's law is used to calculate the flow field in the fiber mats. Results show that most of the injected resins enter into the gap during the injection phase. The resin injection time is extremely short so the duration of the filling process is determined by the final closing action of the mold cavity. Compared with resin transfer molding (RTM), I/CM process can reduce the mold filling time or injection pressure significantly.

• Advanced Composite Materials
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• 제18권2호
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• pp.135-152
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• 2009

Liquid molding processes, such as resin transfer molding, involve resin flow through a porous medium inside a mold cavity. Numerical analysis of resin flow and mold filling is a very useful means for optimization of the manufacturing process. However, the numerical analysis is quite time consuming and requires a great deal of effort, since a separate numerical calculation is needed for every set of material properties, part size and injection conditions. The efforts can be appreciably reduced if similarity solutions are used instead of repeated numerical calculations. In this study, the similarity relations for pressure, resin velocity and flow front propagation are proposed to correlate another desired case from the already obtained numerical result. In other words, the model gives a correlation of flow induced variables between two different cases. The model was verified by comparing results obtained by the similarity relation and by independent numerical simulation.

• 한국기계가공학회지
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• 제16권3호
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• pp.24-29
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• 2017

In this study, a seat cross member was fabricated by optimizing the resin transfer molding processing of CFRP (Carbon Fiber Reinforced Plastics) materials. This seat cross member is used in automotive underbody parts and provides side impact support. The seat cross was manufactured via vacuum resin transfer molding. The process included 1min of resin injection, 8 mins of heating, and 1 min of cooling, for a total molding time of 10mins. Tensile test results showed an average breaking load of 21.50kN, a tensile strength of 404 MPa, and an elastic modulus of 46.2 GPa. As a result, the CFRP seat cross provides the same strength as a similar steel part, but weighs 42% less.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.189-192
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• 2001

Resin transfer molding process has been widely used in the automobile industry, because the product with large area can be manufactured easily and the cost for the manufacturing is lower than that of compression molding and hand lay up method. Since RTM process is suitable for large bus housing panels, in this work, the composite housing panel was manufactured by RTM process and the mechanical properties, surface quality and the condition of manufacturing process were studied.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.111-116
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• 2005

In this study the compatibility of Epoxy resin with Phenolic using three different separation layer techniques was investigated; some important process variables such as pressure, flow front and deformation were monitored in order to get a better understanding of the process.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.139-142
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• 1999

Screw rotors are core parts of screw type air compressors, compressors in refrigerating machines and super chargers of automobiles etc. They are composed of a female and a male rotors which have complex section profiles and helically swept geometry. Screw type compressors have advantages of low noise, high efficiency, less needs in maintenance etc. Usually, machining process of screw rotors requires long machining time using CNC machine designed only for screw rotors, which increase the cost of production. In this work, the screw rotors for air-compressors were manufactured with fiber reinforced epoxy composite materials by resin transfer molding process. The mold for the RTM process was made of aluminum and silicon rubber and was designed for release of helical shape products. Composite screw rotors, manufactured by RTM process, have advantages of lightweight, less cost of production, good characteristics of vibration etc.

• 한국기계가공학회지
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• 제19권12호
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• pp.87-97
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• 2020

In this study, a UV-cured GFRP molding is made using a combination of hand lay-up and resin transfer molding, and its properties are analyzed. The molded plates produced using various vacuum pressures (0 mmHg, -450 mmHg, and -760 mmHg) are examined via a comparison of hand lay-up molding and resin transfer molding. Tests are conducted by processing tensile specimens (ASTM D-5083), flexural test specimens (ASTM D-790), and ILSS test specimens (ASTM D-2344) according to each ASTM standard with a molded plate. Similarly, the UV-cured GFRP molding is compared against GFRP using epoxy. It was confirmed that the mechanical strengths of all the specimens increased when the vacuum pressure was increased and when UV curing was applied. This is believed to be because as the vacuum pressure increases, the pores of the cured specimen are removed, thereby reducing defects, and the bonding force between the glass fiber and the resin is stronger than that of the epoxy resin. It is expected that if resin transfer molding methods and UV-cured resins are used for molding GFRP composites in industry, products with better mechanical properties and faster curing time will be produced.

• 소성∙가공
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• 제15권6호
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• pp.436-440
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• 2006

A rapid tooling (RT) method fur the resin transfer molding (RTM) have been investigated. We fabricated a curved I-beam to verify the method. After creating a three-dimensional CAD model of the beam we fabricated a prototype of the model using a rapid prototyping (RP) machine. A soft mold was made using the prototype by the conventional silicone mold technique. The procedure and method of mold fabrication is described. The mold was cut into several parts to allow easier placement of the fiber preform. We conducted the resin transfer molding process and manufactured a composite beam with the mold. The preform was built by stacking up eight layers of delicately cut carbon fabrics. The fabrics were properly stitched to maintain the shape while placement. The manufactured composites beam was inspected and found well-impregnated. The fiber volume ratio of the fabricated beam was 16.85%.

• Composites Research
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• 제36권5호
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• pp.310-314
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• 2023

VaRTM(Vacuum assisted resin transfer molding)과 VAP(Vacuum assisted process) 공정은 RTM(Resin transfer modling) 공정의 한 종류로서, 대형구조물을 저가에 제작할 수 있는 대표적인 탈 오토클레이브(OOA, Out of Autoclave) 공정이다. 본 논문에서는 VaRTM과 VAP 공정을 상호 비교하기 위하여 수지 충진시험을 진행하였으며, 충진과정과 치수 안정성 등을 상호 비교하였다. 또한, 충진과정을 모사할 수 있는 해석기법을 개발하였으며, 유전센서를 사용하여 수지의 유동선단을 검출하여 이를 해석결과와 상호 비교하였다. 수지 충진시험 결과, 복합재 평판의 총 충진시간은 VAP공정은 48분, VaRTM 공정은 145분으로 측정되어, VAP 공정에 의한 충진시간이 VaRTM 대비 약 67% 단축되었으며, VAP공정이 VaRTM 공정에 비해 복합재 평판의 두께조절능력과 균일도가 우수함을 확인하였다.