• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.57-63
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• 2005

The objective of this research is to investigate the mechanical characteristics of the hybrid fiber reinforced composite rebar, which is manufactured from a braidtrusion process. Braidtrusion is a direct composite fabrication technique, utilizing in-line brading and the pultrusion process. hz order to obtain the mechanical behavior of the glass fiber, carbon fiber, and kevlar fiber, the tensile tests are carried out. The results of the fibers are compared with that of steel. Hybrid rebar specimens with various diameters, ranging from model size (3 mm) to full-scale size (9.5 mm), and various cross sections, such as solid and hollow shape, have been manufactured from the braidtrusion process. The tensile and bending tests for the case of the hybrid rebar, the conventional GFRP rebar, and the steel bar have been carried out. The results of the experiments show that the hybrid rebar is superior to the conventional GFRP rebar and the steel bar, from the viewpoint of tensile and bending characteristics.

• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.121-126
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• 1994

In this thesis, a series of loading tests are conducted in order to investigate the fracture safety as structural materials of GFRP(Glass Fiber Reinforced Plastics) which we wifely used in the developed countries becauses of their natural of anticorrosion and lightweight etc.. In the fracture test, the mid-span displacement, the strain and the yield load of the GFRP pipes are measured for different number of laminates, and fracture energy is estimated. From this study, it is known that GFRP pipe could be used as structural materials in underground buried pipes if their ductility and strength are increased by controlling number of laminates. Furthermore, because of their merit of lightweight, they can contribute greatly to reduction of construe-tlon cost when they are employed.

• Composites Research
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• v.34 no.1
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• pp.35-46
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• 2021

This paper aims to reduce weight by replacing the reinforcements of the B-pillar used in vehicles with CFRP(Carbon Fiber Reinforced Plastics) and GFRP(Glass Fiber Reinforced Plastics) from the existing steel materials. For this, it is necessary to secure structural stability that can replace the existing B-pillar while reducing the weight. Existing B-pillar are composed of steel reinforcements of various shapes, including a steel outer. Among these steel reinforcements, two steel reinforcements are to be replaced with composite materials. Each steel reinforcement is manufactured separately and bonded to the B-pillar outer by welding. However, the composite reinforcements presented in this paper are manufactured at once through compression and injection processes using patch-type CFRP and rib-structured GFRP. CFRP is attached to the high-strength part of the B-pillar to resist side loads, and the GFRP ribs are designed to resist torsion and side loads through a topology optimization technique. Through structural analysis, the designed composite B-pillar was compared with the existing B-pillar, and the weight reduction ratio was calculated.

• Journal of the Korea Institute of Building Construction
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• v.23 no.5
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• pp.509-517
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• 2023

The surge in FRP(Fiber Reinforced Plastic) research signifies the industry's pursuit to counteract the longstanding issue of rebar corrosion. Notably, Carbon Fiber Reinforced Plastic(CFRP) emerges as a commendable alternative, given its superior resistance to both corrosion and chemical interactions, thus positing itself as a potential replacement for traditional steel rebars. However, the layered composition of fibers and resin in CFRP flags a notable susceptibility to elevated temperatures. Despite its promise, comprehensive studies elucidating the full spectrum of CFRP properties remain ongoing. In this investigative study, we meticulously assessed the bond strength of CFRP post-exposure to high thermal conditions. Our findings underscored a parity in bond strength amongst silica sand-coated CFRP, rib-type CFRP, and Glass Fiber Reinforced Plastic(GFRP).

• Magazine of the Korea Concrete Institute
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• v.5 no.3
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• pp.187-194
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• 1993

본 논문에서는 유리섬유의 적층수, 유리섬유의 배향각도에 대한 유리섬유 강화 플라스틱(Glass Fiber Reinforced Plastics ; GFRP)의 인장거동 변화를 고찰하고, 이들의 상관관계를 규명하기 위하여 일련의 GFRP 시험체에 대하여 인장실험을 수행하였다. 시험체는 폭12.5mm, 길이 60mm크기로 일정하게 제작하였으며, 시험체에 대하여 인장실험을 수행하였다. 시험체 제작시 유리섬유로 적층수는 14, 22, 30층, 유리섬유의 배향각도는 0$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$로 하였다. 인장실험시 각 시험체의 파괴양상, 극한하중 및 하중변화에 대한 인장변형율을 조사하였고, 이들 결과를 토대로 유리섬유의 적층수와 배향각도에 따른 GFRP의 극한하중, 응력-변형율 선도 및 탄성계수 등을 비교 분석하였다. 한편 본 논문에서는 유리섬유의 적층수, 직경 변화에 따른 GFRP관의 파괴거동을 고찰하기 위하여 4점 재하법에 의한 GFRP관의 휨파괴실험을 수행하였다. 실험에 사용된 시험체는 길이 1200mm로 하였으며, 유리섬유의 적층수를 30, 35, 40층, 관의 직경을 50, 100, 150mm로 하였다. 파괴실험시 각 시험체의 하중변화에 대한 휨 변형율, 중앙점 처짐량 및 항복하중을 측정하였고, 이들 결과를 토대로 유리섬유으 적층수와 관의 직경에 따라 GFRP관의 항복하중 및 파괴에너지를 비교 분석 하였으며, 항복시 파괴에너지를 추정할 수 있는 제안식을 유도하였다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.10
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• pp.72-79
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• 2021

A circular saw is an effective tool for cutting glass and carbon-fiber hybrid composites. This study investigated tool wear and cut quality when reusing saw blades. The carbide saws wear four times faster than the new ones, and polycrystalline diamond (PCD) is very resistant to tool wear, except at the end of its lifespan. The cut cross-section quality is affected by the blade type, tool wear, and spindle speed. Alternate top bevel (ATB)-type blades are suitable for cutting fiber-reinforced plastics, but triple-chip grind (TCG)-type blades are unsuitable because they cause fiber-pullout defects. Tool wear and low spindle speeds increase the occurrence of arc scratches, due to the rear saw blade. A microscopic examination showed that the burr, which is a mixture of fiber chips and epoxy matrix, was bonded on top, and glass-fiber delamination occurred on the bottom glass-fiber-reinforced polymer (GFRP) surface.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.616-622
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• 2001

In this paper, we analyzed the laminated composite sandwich plate structure of honeycomb core with changing values of the designing parameters. As a result, in designing parameters of that, the more height and thickness of the laminated composite plate's core, the more increase of natural frequency. The laminated angle has the maximum value when the plate of honeycomb core is join to opposite direction. This paper shows that the natural frequency of CFRP is higher than that of GFRP, and also impact strength marks maximum value in case of antisymmetry than symmetry of core. Also it shows that the mode shapes are various along with the angle-ply of laminated composite plate.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.703-709
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• 2001

In this paper, we analyzed the laminated composite sandwich plate structure of truss core with changing values of the designing parameters. As a result, in designing parameters of that, the more height and thickness of the laminated composite plate's core, the more increase of natural frequency. In this type of structure, in the case of applying core of the laminated composite plate and antisymmetric stacking, natural frequency has high value and we calculated the optimum angle-ply making natural frequency maximum. Natural frequency of CFRP is higher than that of GFRP. Both are materials of the laminated composite plate. The mode shapes are various along with the angle-ply of the laminated composite plate.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.10a
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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.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.1
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• pp.33-41
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• 1988

A turning (facing) test on Glass Fiber Reinforced Plastics was performed with several tool materials, e.g., cemented carbides, cermet and ceramic, and the wear patterns and wear rate were analyzed to clarify the relation between physical(mechanical) properties and flank wear of cutting tool. The main results are obtained as follows: (1) When cutting speed is increased, the flank wear in every tool material grows the abnormal wear in the shape of triangle at a certain speed, i.e., a critical speed. (2) When cutting speed is increased, the wear rate in experimental tool material starts to increase remarkably at a critical speed. (3) The thermal conductivity among the properties of the tool material and the thermal crack coefficient of it are almost in proportion to the critical speed. (4) The order of performance in tool materials for cutting GFRP is K 10, M10, P20, TiC, CB.