탄소섬유 강화 PA6/PPO 복합재료의 섬유 배향에 따른 충격강도 및 열팽창 거동에 관한 연구

원희정 ( Hee Jeong Won ),성동기 ( Dong Gi Seong ),이진우 ( Jin Woo Lee ),엄문광 ( Moon Kwang Um ) 한국복합재료학회 2014 Composites research Vol.27 No.2

사출 성형을 통해 제조된 단섬유 강화 복합재는 사출 성형 중 발생하는 수지 유동으로 인해 동일 시편 내에서도 다양한 섬유 배향을 갖는다. 이러한 섬유의 배향은 최종 복합재의 기계적, 열적 특성에 많은 영향을 주므로, 본 연구에서는 사출 성형된 탄소단섬유 강화 PA6/PPO 복합재의 섬유 배향을 광학 현미경 분석을 통하여 측정하고 섬유의 배향이 복합재의 충격강도 및 열팽창 계수에 미치는 영향을 분석하였다. 충격강도의 경우에 섬유의 배향이 크랙이 전파되는 방향에 수직으로 배향되어 있을수록 더 높은 충격강도를 보였으며, 이는 섬유의 배향에 따른 충격내성 강화 메커니즘과 밀접한 연관성을 보여주었다. 열팽창 계수의 경우에는 섬유가 열팽창률을 측정하는 방향과 동일한 방향으로 배향되어 있을수록 더 낮은 열팽창계수를 보였으며, 이 결과 역시 섬유의 배향이 열팽창 특성에 미치는 메커니즘과 밀접한 연관성을 보였다. Short fiber reinforced composites manufactured by injection molding have diverse fiber orientations variable with measuring positions even in the same specimen, which is caused by the flow induced fiber orientation. Fiber orientations considerably affect the mechanical and thermal properties of final composite products. In this study, fiber orientation of injection molded carbon fiber reinforced PA6/PPO composite was measured at several points of the specimen by optical microscopy analysis and the corresponding izod impact strength, coefficients of thermal expansion (CTE) were also measured to investigate the influence of local fiber orientation on the mechanical and thermal properties. Izod impact strength where fiber was perpendicular to the direction of crack propagation was higher than where fiber was parallel to the direction, which could be explained be the impact resistance reinforcing mechanism by fiber orientation. CTE was also lower where fiber was parallel to the measurement direction of CTE than where fiber was perpendicular to the direction, which could be also explained by the dimensional stability mechanism by fiber orientation.

유리섬유 강화 플라스틱의 역학적 거동 구현을 위한 Digimat와의 연성해석 연구

김영만,김용환 한국전산구조공학회 2019 한국전산구조공학회논문집 Vol.32 No.6

유한요소법(finite element method)은 다양한 분야에서 재료의 역학적 거동을 더욱더 현실적으로 해석하고 예측하는 방법으로 다양한 분야의 제품 개발에 적용되고 있다. 하지만 섬유배향과 변형률 속도가 역학적 특성에 영향을 미치는 유리섬유 강화 플라스틱 복합재료에 관한 수치해석을 이용한 접근 방법은 현재까지 다소 어려움이 있다. 본 연구의 목적은 고분자, 고무, 금속 등과 같은 다양한 복합재료를 위한 선형, 비선형 다중스케일 재료 모델링 프로그램인 Digimat의 수치해석 재료 모델을 활용하여 유리섬유 강화 플라스틱 복합재료의 역학적 특성을 정의하고 검증하는 것에 있다. 또한 이를 통해 좀더 현실 적으로 고분자 복합재료의 거동을 예측하고자 한다. 이를 위해 다양한 고분자 중 30wt%의 단섬유 질량 비율을 갖는 폴리부 틸렌 텔레프탈레이트(polybutylene terephthalate, PBT)의 섬유배향과 변형률 속도에 따른 인장 특성을 참고문헌을 통해 조사하였다. 또한 Moldflow 프로그램을 사용한 사출해석을 통해 유리섬유 배향 정보를 계산하였으며 이를 매핑(mapping) 과 정을 통해 유한요소 인장 시편 모델에 전달하였다. 대표적인 유한요소 상용 프로그램 중 하나인 LS-DYNA는 유리섬유 배향과 변형률 속도에 따른 복합재료의 인장 특성을 연구하기 위해 Digimat과의 연성해석(coupled analysis)에 활용되었다. 그리고 유리섬유 강화 플라스틱 복합재료를 해석하기 위한 LS-DYNA의 다양한 비등방성(anisotropic) 재료 모델들의 장단점을 서로 비교하고 평가하였다. Finite element method (FEM) is utilized in the development of products to realistically analyze and predict the mechanical behavior of materials in various fields. However, the approach based on the numerical analysis of glass fiber reinforced plastic (GFRP) composites, for which the fiber orientation and strain rate affect the mechanical properties, has proven to be challenging. The purpose of this study is to define and evaluate the mechanical properties of glass fiber reinforced plastic composites using the numerical analysis models of Digimat, a linear, nonlinear multi-scale modeling program for various composite materials such as polymers, rubber, metal, etc. In addition, the aim is to predict the behavior of realistic polymeric composites. In this regard, the tensile properties according to the fiber orientation and strain rate of polybutylene terephthalate (PBT) with short fiber weight fractions of 30wt% among various polymers were investigated using references. Information on the fiber orientation was calculated based on injection analysis using Moldflow software, and was utilized in the finite element model for tensile specimens via a mapping process. LS-Dyna, an explicit commercial finite element code, was used for coupled analysis using Digimat to study the tensile properties of composites according to the fiber orientation and strain rate of glass fibers. In addition, the drawbacks and advantages of LS-DYNA's various anisotropic material models were compared and evaluated for the analysis of glass fiber reinforced plastic composites.

섬유강화 고분자 복합재료 사출성형품의 섬유배향상태

이동기,심재기,김진우 한국공작기계학회 2005 한국생산제조학회지 Vol.14 No.1

Injection molding is the most widely used process for the industrial forming of plastic articles. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation. orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of welding parts in injection-molded products is assessed. And the effects of fiber content and injection mold shapes on the fiber orientation in case of fiber reinforced polymeric composites are studied experimentally.

탄소섬유지의 섬유 구조가 가스확산층의 유효열전도도와 유동 특성에 미치는 영향에 관한 수치적 연구

김형민 대한기계학회 2024 大韓機械學會論文集B Vol.48 No.6

고분자전해질 연료전지의 기체확산층은 반응기체인 수소와 산소를 촉매 층에 공급하며 반응으로 생성된 수분과 열을 적절히 배출시켜 전지가 안정적인 운전상태를 유지할 수는 있는 특성을 가지고 있어야한다. 기체확산층에서 열의 확산과 기체 및 수분의 거동을 분석하는 것은 최적의 기체확산층을 만들기 위한 필수적인 요소이다. 이 연구에서는 실린던 형상의 탄소섬유 수와 배향을 적용한 확률적 재생성법으로 모델링한 탄소 섬유 지를 이용하여 열전도 및 단상, 다상 격자볼츠만해석 결과로부터 탄소섬유의 방위각의 범위에 따라 생성된 탄소섬유의 구조가 유효열전도도, 투과도 및 수분포화도에 미치는 영향을 평가하였다. 탄소섬유의 방위각의 범위가 에서 로 커지면 탄소섬유가 관통방향으로 더 기울어져 유효열전도도는 커지고, 수분포화도 기울기가 낮아져 열과 수분 배출이 원활해진다. 또한 공극률이 커지면 투과도는 커지지지만 유효전도도는 감소한다. 따라서 최적의 기체확산층 섬유구조는 탄소섬유의 방위각 범위가 이고 공극률이 0.76인 것으로 평가되었다. The gas diffusion layer in a polymer electrolyte membrane fuel-cell must supply reaction gases—hydrogen and oxygen—to the catalytic layer and effectively release the generated water and heat from the reaction to maintain stable cell operation. To optimize the gas diffusion layer, it is crucial to analyze heat diffusion, gas behavior, and the dynamics of water within it. This study used carbon fiber paper modeled into a cylindrical shape and fibers were oriented using a stochastic regeneration method. The structure of carbon fibers was evaluated for its thermal conductivity, permeability, and saturation rate. This evaluation was based on the range of fiber orientation angles and conducted using multiphase lattice Boltzmann analysis. Based on this analysis, it was found that as the fiber orientation angle range increases and the structure of the carbon fiber inclines in the flow direction, effective heat conductivity increases, and the moisture saturation gradient decreases; thereby, promoting heat and moisture discharge. Furthermore, as porosity increases, effective conductivity decreases, and permeability increases. Thus, the optimal fiber structure for the gas diffusion layer is determined as having an orientation angle range of π/3 and a porosity of 0.76.

섬유강화 복합재료 사출성형품의 섬유배향상태

이정주,김진우,김혁,한길영,심재기,이동기 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-

Injection molding is the most widely used process for the industrial forming of plastic articles. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation·orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of welding parts in injection-molded products is assessed. And the effects of fiber content and injection mold shapes on the fiber orientation in case of fiber reinforced polymeric composites are studied experimentally.

섬유강화 복합재료 사출성형품의 섬유배향상태

이정주(J. J. Lee),김진우(J. W. Kim),김혁(H. Kim),한길영(G. Y. Han),심재기(J. K. Sim),이동기(D. G. Lee) 한국생산제조학회 2004 한국생산제조시스템학회 학술발표대회 논문집 Vol.2004 No.4

Injection molding is the most widely used process for the industrial forming of plastic articles. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of welding parts in injection-molded products is assessed. And the effects of fiber content and injection mold shapes on the fiber orientation in case of fiber reinforced polymeric composites are studied experimentally.

섬유강화 복합재료의 사출성형에 있어서 섬유배향에 미치는 성형조건의 영향

이동기,한길영,김성용 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.2

Injection molding is a very important industrial process for the manufacturing of plastics objects. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of weld-line parts in injection-molded products is assessed. And the effects of fiber content and injection molding conditions on the fiber orientation functions are also discussed.

FRP의 사출성형에 있어서 섬유배향상태와 섬유함유율분포에 관한 연구

김진우,이동기 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-

Injection molding is a very important industrial process for the manufacturing of plastics objects. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separationㆍorientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of weld-line in injection-molded products is assessed. And the effects of fiber content and injection mold-gate conditions on the fiber orientation are also discussed.

화상처리에 의한 춉트 스트랜드 섬유배향의 분포측정

김혁,윤성운,한길영,심재기,이동기 조선대학교 생산기술연구소 1995 生産技術硏究 Vol.17 No.2

In order to examine the accuracy of intensity method, the fiber orientation distribution of chopped strand reinforced polymeric composites is measured using image processing. Theoretical and experimental results of fiber orientation function are compared with each other for the composites having different fiber content and fiber orientations. An intensity method is used for the experimental investigation and the measured fiber orientation function is compared to the calculated one. The results show that, firstly, the feature of fiber orientation can be represented and identified by the fiber orientation function J measured and theoretical fiber orientation functions, J_(M) and J, respectively and related as J_(M)=0.73J. Secondly, as far as the measuring of fiber orientation is concerned, the intensity method is, in general, found to be quite effective due to its feature of using the intensity difference in the measuring ranges. Finally, the accuracy of the method increases when the fiber with less clash is considered.

FRP의 사출성형에 있어서 섬유배향상태와 섬유함유율분포에 관한 연구

이동기(Dong-Gi Lee),심재기(Jea-Ki Sim),김진우(Jin-Woo Kim) 한국생산제조학회 2006 한국생산제조학회지 Vol.15 No.4

Injection molding is a very important industrial process for the manufacturing of plastics objects. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation?orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of weld-line in injection-molded products is assessed. And the effects of fiber content and injection mold-gate conditions on the fiber orientation are also discussed.