• Title/Summary/Keyword: 진공백 성형

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Study of Cure Behavior of the External and Internal of Composite Parts (경화공정에 따른 복합재 부품 외부와 내부의 경화 거동 차이에 대한 연구)

  • Hyun, Dong Keun;Lee, Dong Seung;Shin, Do Hoon;Kim, Ji Hoon
    • Composites Research
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    • v.33 no.5
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    • pp.302-308
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    • 2020
  • We measured the thermal conductivity of composite materials manufactured by the autoclave and vacuum bag only processes and predicted the cure behavior of the external and internal of composite parts with a cure kinetics model. The temperature difference between the external and internal depends on the processes because of the change of thermal conductivity. In the autoclave process, the temperature and cure behavior of the internal were similar to those of the external because of the high thermal conductivity. However, the temperature of the internal of the vacuum bag only process was different from that of the external. The difference can influence the part quality and evacuation of air. Compression tests were performed to find the mechanical property using 0° unidirectional specimens. The composite of the vacuum bag only process was found to have a lower compressive strength than that of the autoclave process.

Study of Cure Kinetics of Vacuum Bag Only Prepreg Using Differential Scanning Calorimetry (시차주사열량계를 이용한 진공백 성형 프리프레그의 경화 거동 연구)

  • Hyun, Dong Keun;Lee, Byoung Eon;Shin, Do Hoon;Kim, Ji Hoon
    • Composites Research
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    • v.33 no.2
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    • pp.44-49
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    • 2020
  • The cure kinetics of carbon fiber-reinforced prepreg for Vacuum Bag Only(VBO) process was studied by differential scanning calorimetry (DSC). The total heat of reaction (ΔHtotal = 537.1 J/g) was defined by the dynamic scanning test using prepregs and isothermal scanning tests were performed at 130℃~180℃. The test results of isothermal scanning were observed that the heat of reaction was increased as the temperature elevated. The Kratz model was applied to analyze the cure kinetics of resin based on the test results. To verify the simulation model, the degree of cure from panels using different cure cycles were compared with the measurement. The simulation model showed that the error against the experimental value was less than 3.4%.

Preparing of Carbon Fiber Composites Using by Vacuum Bag Hot-press Molding Process and Comparison with the other Molding Processes (진공백 핫 프레스 성형공정을 이용한 탄소섬유 복합재료의 제조와 공정비교)

  • Heo, Won-Wook;Jeon, Gil Woo;An, Seung Kook
    • Composites Research
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    • v.33 no.2
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    • pp.76-80
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    • 2020
  • In this study, vacuum bag hot-press (V-HP) process can be used as an out-of-autoclave (OOA) process by improving the inefficient process of the autoclave forming method with excellent physical properties and surface quality. A carbon fiber composite was molded via V-HP process and analyzed the physical properties and microstructures between composites manufactured by autoclave (AC) process and hot-press process (HP). The tensile strength of the composite materials using the V-HP process was 320.6 MPa and the AC process samples found to be substantially close to the tensile strength of 335.3 MPa. As a result of confirming the surface quality of the composite material using SEM, it was confirmed that in the V-HP process, the removal state of pores due to volatile solvent in the resin was slightly lower than that of the AC process, but it had a considerably superior surface compared to the HP process.

A Study on the Low Pressure Injection Molding of Automotive Seat-back Cover (자동차용 시트백 커버의 저압사출성형에 관한 연구)

  • Ko, Byung-Doo;Ham, Kyoung-Chun;Jang, Dong-Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.12
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    • pp.100-106
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    • 2008
  • In this paper, the injection molding process of automotive seat-back cover is analyzed in terms of simulation and of experiment. FE analysis was used to obtain molding conditions such as injection pressure, filling pattern, packing, shrinkage. Vacuum system for low pressure injection molding is developed in the experiment. Low pressure injection molded parts have been compared with conventional molded parts in terms of molding quality and mechanical properties. Based on the results, good product and the productivity improvement can be obtained in low pressure injection molding for automotive seat-back cover.

A study on the variation of in-plane and out-of-plane properties of T800 carbon/epoxy composites according to the forming pressure (성형 압력에 따른 T800 탄소섬유/에폭시 복합재료의 평면 내.외 물성 변화에 대한 연구)

  • Park, Myong-Gil;Cho, Sung-Kyum;Chang, Seung-Hwan
    • Composites Research
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    • v.23 no.6
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    • pp.61-66
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    • 2010
  • In this paper, the variation of mechanical properties of T800 carbon/epoxy composites according to the forming pressure, which was referred to previous studies on a filament winding process, were investigated. The specimens of all the tests were fabricated by an autoclave de-gassing molding process controlling forming pressure (absolute pressures of 0.1MPa, 0.3MPa, 0.7MPa including vacuum) and water jet cutting after fabricating composite laminates. Various tensile tests were performed for in-plane properties and interlaminar properties were also measured by using Iosipescu test jig. Fiber volume fraction was measured to correlate the property variation and the forming pressure. This properties are expected to be utilized in the design of Type III pressure vessel for hydrogen vehicles which uses the same carbon fiber (T800 carbon fiber) for the filament winding process.

A study on the bonding strength of co-cured T800/epoxy composite-aluminum single lap joint according to the forming and additional pressures (동시 경화법으로 제조된 T800/에폭시 복합재료-알루미늄 단면겹치기조인트의 성형압력 및 부가압력에 따른 접착강도에 관한 연구)

  • Son, Dae-Sung;Bae, Ji-Hun;Chang, Seung-Hwan
    • Composites Research
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    • v.24 no.5
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    • pp.23-28
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    • 2011
  • In this paper, the bonding strengths of co-cured T800 carbon/epoxy composite-aluminum single lap joints with and without additional pressures were investigated using the pressure information induced by the fiber tension during a filament winding process. The specimens of all the tests were fabricated by an autoclave vacuum bag de-gassing molding being controlled forming pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa including vacuum). A special device which can act uniform additional pressures on the joining part of the single lap joint specimen was designed to measure the bonding strengths of composite-aluminum liners of type III hydrogen pressure vessel fabricated by a filament winding process. After the three different additional pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa) were applied to the specimens the effect of the additional pressures on the bonding strengths of the co-cured single-lap joints were evaluated.

A Study on the Surface Grinding Temperature Characteristics of the Carbon Fiber Epoxy Composite Materials (탄소섬유 에폭시 복합재료의 평면 연삭온도 특성에 관한 연구)

  • 한흥삼
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.04a
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    • pp.441-446
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    • 2000
  • Although the net-shape molding of composites is generally recommended, molded composites frequently required cutting or grinding due to the dimensional inaccuracy for precision machine elements. During the composite machining operations such as cutting and grinding, the temperature at the grinding area may increase beyond the allowed limit due to the low thermal conductivity of composites, which might degrade the matrix of composite. Therefore, in this work, the temperature at the grinding point during surface grinding of carbon fiber epoxy composite was measured. The grinding temperature and surface roughness were also measured to investigate the surface grinding characteristics of the composited. The experiments were performed both under dry and wet grinding conditions with respect to cutting speed, feed speed, depth of cut and stacking angle. From the experimental investigation, the optimal conditions for the composite plain grinding were suggested.

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Design and Performance Evaluation of Carbon Fiber/Epoxy Composite-aluminum Hybrid Wheel for Passenger Cars (자동차용 탄소섬유/에폭시 복합재료-알루미늄 하이브리드 휠 설계 및 성능평가)

  • Hong, Jin-Ho;Yoo, Seong-Hwan;Chang, Seung-Hwan
    • Composites Research
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    • v.26 no.6
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    • pp.386-391
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    • 2013
  • In this paper, a carbon fiber/epoxy composite-aluminum hybrid wheel for passenger cars was suggested for better performance and a prototype was fabricated and tested. Adhesive bonding between aluminum part and a composite rim part was used, and the bonding length and thickness were determined by finite element analysis. For self alignment and the function of bonding jig the special structure with a groove and a protrusion was applied. To evaluate the performance of the hybrid wheel various FE analyses were carried out. Inner and outer molds were prepared for the composite rim part and the thermoformed composite part was bonded to the aluminum part. Vibration tests revealed that the hybrid wheel had 16% higher resonance frequency and 32% higher damping capacity with 10% weight reduction.

Development and Analysis of the Autoclave Alternative Composite Material Molding Process Using a Pressure Device (가압장치를 이용한 오토클레이브 대체 복합재료 성형공정 개발 및 분석)

  • Kim, Jung-Soo;Kim, Byung-Ha;Joe, Chee-Ryong
    • Composites Research
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    • v.27 no.6
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    • pp.254-259
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    • 2014
  • In this study, a device and pressure press process that is able to substitute autoclave process is developed. This process complements disadvantages of autoclave process which are long process-time and high production cost. The developed device provides air pressure as well as the vacuum which are greatest feature of autoclave process. The device is sealed using hydraulic pressure to keep the air pressure inside the mold. The transfer of the heat is designed to be direct. The heating and pressure charging time are decreased by reducing the interior space. Tooling cost is reduced dramatically compared to autoclave process. Spring-back phenomenon is measured and compared. The temperatures of several parts of the mold during molding are measured. The fiber volume fraction of the parts molded by autoclave process and by the developed process are compared.

Effect of Fabrication Methods on Static Strength of Polymer Based Composites under the Low Temperature Range (적층 방법에 따른 복합재의 저온 영역 하에서 정적 강도 변화)

  • Eom, Su-Hyeon;Dutta, Piyush K.;Gwon, Sun-Cheol;Kim, Guk-Jin;Kim, Yun-Hae
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.7-12
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    • 2003
  • When the wind turbine is used in cold regions, the mechanical properties and dimension stability of the blade will be changed. The proposal of this paper is to test the durability of the blade for wind turbine. It is necessary to select the most comfortable materials and fabrication processes for more stable wind turbine blade in cold regions. To select the most comfortable materials and processes, the static strength has to know through the tensile static tests at the severe condition as cold regions. First, the tensile static specimens made by RIM (Resin injection molding) process & vacuum bagging process with reinforcement materials and resin. Tensile static tests were carried out on three laminate lay-ups (carbon prepreg, carbon fiber dry fabric and glass fiber dry fabric) at different test temperature($24^{\circ}$, $-30^{\circ}$), determining properties such as the mechanical strength, stiffness and strain to failure. At different test temperature, in order to test the tensile strengths of these specimens used the low temperature chamber. Next, the results of this test were compared with each other. Finally, the most comfortable materials and fabrication processes can select based on these results. The results show the changes in the static behavior of three laminate lay-ups at different test temperatures. At low temperatures, the static strengths are higher than the ones at room temperature.

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