• 한국산업안전학회:학술대회논문집
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• 한국안전학회 2003년도 추계 학술논문발표회 논문집
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• pp.113-117
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• 2003

The reliability of machined fiber reinforced composites (FRC) in high strength applications and the safety in using these components are often critically dependent upon the quality of surface produced by machining since the surface layer may drastically affect the strength and chemical resistance of the material [1,2,3,4]. Current study will discuss the characterization of fiber pull-out in orthogonal cutting of a fiber-matrix composite materials. A sparsely distributed idealized model composite material, namely a glass reinforced polyester (GFRP) was used as workpiece. Analysis method employs a force sensor and the signals from the sensor are processed using AR time series model. The experimental correlation between the fiber pull-out and the AR coefficients is examined first and effects of fiber orientation, cutting parameters and tool geometry on the fiber pull-out are also discussed.

• 대한기계학회논문집
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• 제18권9호
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• pp.2396-2403
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• 1994

An experimental study on material characterization and mechanical properties of SMC(Sheet Molding Compounds) compression method parts was carried out. Simple compression test using grease oil as a lubricant was carried out to characterize flow stress of SMC at elevated temperatures. Two different mold temperatures, $130^{\circ}C{\;}and{\;}150^{\circ}C$ and two different mold speeds, 15, 45 mm/min were used for preparing the specimen of SMC compression molded parts. Surface roughness, tensile, and 3-point bending tests were used to determine the effects of molding temperatures and speeds on mechanical properties of compression molded SMC parts. Orientation and distribution of glass fiber in the compression molded SMC parts were also investigated by photographing the burnt flat specimen and taking SEM(Scanning Electron Microscope) of cross-sectional T-specimen.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.208-212
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• 1999

In the use of glass fiber reinforced plastics(GFRP), cutting is often necessary. But the most of past studies have been interested in the effect of fiber orientation on tool wear. In this study, the effects of fiber contents on tool wear were investigated experimentally. By proper selection of cutting tool, the variables are cutting speed and fiber contents of 10, 20, 30wt% with fixed feed rate and depth of cut.

• 폴리머
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• 제36권5호
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• pp.555-563
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• 2012

사출 성형품에서 발생되는 뒤틀림은 성형공정 중 제품의 불균일한 수축과 잔류응력의 이완으로 인하여 나타나는 현상이다. 휨이나 뒤틀림 현상을 방지하기 위해서 성형품이 강성이 있도록 설계하거나 수지에 유리섬유 등으로 보강하여 사용한다. 본 연구에서는 플라스틱의 성형품에서 성형품의 설계에 따른 뒤틀림 현상을 성형조건 별로 알아보았다. 성형품의 설계는 리브로 보강된 두 종류와 보강 리브가 없는 시편을 사용하였다. 수지는 유리섬유로 보강된 비결정성 수지인 PC와 ABS를 사용하였다. 실험결과 휨은 리브의 설계에 따라 큰 변화를 보였다. 게이트 주변, 게이트 반대쪽, 그리고 흐름방향쪽 등 측정위치에 따라서 휨은 다양하게 나타났다. 이러한 휨의 결과는 유리섬유의 배향과도 크게 관련이 있음을 컴퓨터 해석을 통해 확인할 수 있었다. 리브가 없는 단순 평판에서 휨이 가장 작게 나타났으며, 리브가 흐름방향으로 놓여있는 경우가 휨에 대한 큰 저항을 보였다. 시편에 나타난 휨은 성형조건보다는 제품의 설계에 따라 크게 변하였다. 리브의 설계와 그에 따른 게이트의 위치 설정은 유리섬유의 배향과 직접적인 관련이 있으므로 성형품의 휨 조절에 매우 중요함을 보여주었다.

• 한국안전학회지
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• 제16권1호
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• pp.88-93
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• 2001

본 연구에서는 복합소재인 GFRP(Glass Fiber Reinforced Polyester)의 2차원 절삭공정에서 절삭 메커니즘과 소재의 신뢰도 및 안전성과 밀접한 관련이 있는 표면정도를 중심으로 한 공정의 특성화를 시도하고, 주파수 분석에 관하여도 논의한다. 구체적으로는, 공정중 발생하는 절삭력 신호를 AR(Autoregressive) 모델링하여 해석에 사용한다. 특히, 특징추출과정을 통해 AR계수로 이루어진 패턴벡터 중 다양한 절삭 메카니즘에 민감한 계수만 선택할 수 있다. 이들 계수와 절삭 메커니즘과의 실험적 관계를 설정함으로써 섬유경사각(Fiber orientation angle), 절삭 변수 그리고 공구형상이 절삭 메커니즘에 미치는 영향을 평가하였다.

• 수산해양기술연구
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• 제21권1호
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• pp.75-81
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• 1985

직교이방향 이층 유리섬유 강화 Epoxy 수지를 사용하여 인장축에 대해 섬유방향이 0$^{\circ}$, 15$^{\circ}$, 25$^{\circ}$ 및 45$^{\circ}$인 시료로 인장시험 및 전기절연 강도시험을 통하여 얻은 결과는 다음과 같다. 1) 섬유방향이 인장축에 대해 0$^{\circ}$에서 45$^{\circ}$로 증가함에 따라 항복응력 및 파단응력은 감소하는 경향이고 특히 0$^{\circ}$와 15$^{\circ}$ 사이에서 급격한 변화율을 보인다. 2) 파단시 변화율은 인장방향에 대한 섬유방향이 45$^{\circ}$인 경우 최대치를 나타냈고 15$^{\circ}$~45$^{\circ}$ 범위에서 급격한 변화율을 보인다. 3)섬유의 방향이 동일할 경우 인장력을 많이 받은 시료일수록 최대절연강도 값은 낮아졌고 인장방향과 섬유방향의 교각이 증가할수록 최대절연강도 값을 나타내는 압축응력의 값은 낮은 점으로 이동하는 경향을 보였다. 4) 기계적 특성과 같이 섬유방향이 45$^{\circ}$인 경우의 시료가 가장 나쁜 전기적 절연강도 특성을 나타냈다.

• Tribology and Lubricants
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• 제12권1호
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• pp.6-14
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• 1996

Experimental investigation on the tribological behavior of fiber-reinforced plastics(FRP) has been studied. It is shown that the frictional behavior of carbon FRP depends on the fiber-orientation while glass FRP does not. The friction coefficient values for carbon FRP were about 0.8, 0.3, and 0.2 for normal, 45$^{\circ}$ and 0$^{\circ}$ sliding directions respectively. Also, the applied load was found to affect the friction coefficient. In the case of this work, 50 gf resulted in the highest value while 200 gf resulted in the lowest value. The friction coefficients for higher loads fell in between the two extreme values.

• 한국염색가공학회지
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• 제34권1호
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• pp.46-57
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• 2022

In this study, the relationship between fiber orientation and mechanical properties with the injection pressure of polyamide-6/glass fiber composite materials manufactured by the injection molding process was investigated. Also, an actual experimental data and finite element model-based simulation data were analyzed. Specimens were manufactured through the injection molding process setting the injection pressure differently to 700, 800, 900, and 1000 bar, respectively. A morphological analysis and orientation of the PA6/GF composite material were observed using Optical microscope. Through tensile and flexural strength tests, the mechanical properties of the PA6/GF composite materials with the injection pressure were studied. As a result, it was confirmed that the mechanical properties were the superior under the injection pressure of 900 bar molding conditions. In addition, the mechanical properties of the actually manufactured specimen (PA6/GF) and virtual engineering S/W((Digimat, Abaqus) were used to compare and analyze the analysis results for the mechanical properties, and based on the reliable DB, the physical properties of the PA6/GF composite characteristics were studied.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1616-1622
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• 2001

Fiber composite materials are widely used in aerospace industries due to their high specific strength and stiffness. Especially, the increasing use of polymer composite materials for injection of automobile components has led to a considerable interest in the application of stress pattern analysis by thermal emission to these composite materials. Therefore, in this study the microstructure of glass fiber orientation at the parent and weld line of polycarbonate is observed by a light transmission. And we also investigate a stress concentration model of a notch including short glass fibers. Especially the polymer injection weld reorients the fiber to suggest a new method for the evaluation of inhomogeneous deformation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.132-137
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• 2012

To enhance the CAE accuracy, the definition of material behavior is one of key influence on the result. In case of plastic material with fiber reinforcement, the anisotropic material behavior should be taken into account to increase of CAE accuracy. BASF has developed an innovative CAE tool, ULTRASIM$^R$, which is capable of generating material models of thermoplastic materials for structural simulation. ULTRASIM$^R$, not only the glass fiber orientation effect, but also the weld line effect, tensile-compression anisotropy, strain rate effect are combined in a non-linear material law, which will be evaluated in a unique failure criterion, thus resulting in an highly accurate CAE approach.