• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.674-680
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• 2013

As the range of marine leisure activity gradually expands to ocean-going, a habitable cruise boat has been getting the limelight. Advanced countries in the marine leisure industry in Europe and North America have already secured their competitiveness in designing and building cruise boats by elegant design, ergonomic structure and fuel efficiency through the adoption of light-weight hull materials. In contrast, mostly small power boats are developed and built in Korea, and GFRP take up the most of hull materials. This study inquired into the design and characteristics of a 50ft-class CFRP that ocean-going is possible. The hull-form of the CFRP cruise boast were analyzed to propose a hull form for the designed ship (MMU-C.B), and based on that, the design model of the MMU-C.B was built. Finally, the MMU-C.B's characteristics of the resistance performance and hull-planing were found by comparative reviews with the results of model tests of GFRP pleasure yachts.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.11
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• pp.447-455
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• 2017

At the modern industry, the composite material has been widely used. Particularly, the material of carbon fiber reinforced plastic hardened with resin on the basis of fiber is excellent. As the specific strength and rigidity are also superior, it receives attention as the light material. Among these materials, the carbon fiber reinforced plastic using carbon fiber has the superior mechanical property different from another fiber. So, it is utilized in vehicle and airplane at which high strength and light weight are needed at the same time. In this paper, the tensile property due to the fiber design is investigated through the analysis study with CT specimen composed of carbon plastic reinforced plastic. At the stress analysis of CFRP composite material with hole, the fracture trend at the tensile environment is examined. Also, it is shown that the lowest stress value happens and the deformation energy of the pre-crack becomes lowest at the analysis model composed of the stacking angle of 60° through the result due to the stacking angle. On the basis of this study result, it is thought to apply the foundation data to anticipate the fracture configuration at the structure applied with the practical experiment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.32-38
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• 2018

In this study, the one-piece propeller shaft composed of carbon/epoxy was designed and manufactured for 4 wheel drive automobiles that can bear the target torsional torque performance of 3.5kN.m. For the CFRP tube, braiding machine was used to weaving carbon fiber and it was formed the braided yarns with the braid angle ${\pm}45^{\circ}$ and axial yarns to improve strength of the lengthwise direction. The final CFRP tube of propeller shaft was evaluated through the torsional torque test. The CFRP propeller shaft satisfied requirement of the target torsional maximum torque of 3.5kN.m. Also, it was found that the one-piece composite propeller shaft with CFRP tube had 30% weight saving effect compared with a two-piece steel propeller shaft.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.920-925
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• 2012

A study of vehicle weight lightening has been progressed to reduce the fuel consumption. In this paper, the body floor in an EV (Electric Vehicle) bus has been applied by composites as CFRP and GFRP. In order to analyse a various reliability and safety, an experiment and FEM analysis was carried out to obtain weight lightening. Especially, the joint. An effective design is obtained through an experiment as well as FEM analysis. Results of stress analysis of GFRP material showed twice as much displacement than those of CFRP material. Among three kinds of joint methods, the bond joint method is occurred to a substantial shape change in the body and floor. It is found that the rivet joints are fairly suitable for stress sustaining capability.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.139-149
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• 2011

The combustion chamber and nozzle of a liquid rocket engine need thermal protection against the high temperature combustion gas. The nozzle extension of a high-altitude engine also has to be compatible with high temperature environment and several kinds of cooling methods including gas film cooling, ablative cooling and radiative cooling are used. Especially for an upper-stage nozzle extension having a large expansion ratio, the weight impact on the launcher performance is crucial and it necessitated the development of light-weight refractory material. The present survey on the nozzle extension materials employed in the liquid rocket engines of USA, Russia and European Union has revealed a trend that the heavier metals like stainless steels and titanium alloys are being substituted with light weight carbon fiber or ceramic matrix composite materials.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.818-824
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• 2018

CFRP is often used as lightweight hull material for luxury yachts or special-service ships. An electric propulsion system is also eco-friendly, and has been trialled to equip a small vessel as its main propulsion. In this study, replacing the hull materials and propulsion system with CFRP and electric motors, we made an estimate of the effect of weight reduction and compared it to the original design, for this purpose a case study was conducted on a 45-ft yacht. When redesigning structures with CFRP, we applied the reinforcement content of the carbon fiber in the same way as the original (GC = 0.4), and when changing to the electric propulsion system, we designed motors and battery packs to achieve the same performance as the original. The result showed that CFRP and the electric propulsion system could make the structural and machinery weights 45 % and 58 % lighter, respectively. However, in terms of efficiency, it was confirmed that the electric propulsion system is practically inefficient because it requires a huge amount of battery packs for the same navigation range with diesel engines.

• Composites Research
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• v.36 no.1
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• pp.1-15
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• 2023

Demand for energy consumption reduction is increasing according to the development expectations of future mobility. Lightweight structural materials are known as a method to reduce greenhouse gas emissions and improve energy efficiency. In particular, fiber reinforced polymer composite (FRP) is attracting attention as a material that can replace existing metal alloys due to its excellent mechanical properties and light weight. In this paper, industrial applications and research trends of carbon fiber reinforced composites (CFRP, carbon FRP) and self-reinforced composites (SRC) were reviewed based on the reinforcement, polymer matrix, and manufacturing process. In order to overcome the expensive process cost and long manufacturing time of the epoxy resin-based autoclave method, which is mainly used in the aircraft field, mass production of CFRP-applied electric vehicles has been reported using a high-pressure resin transfer molding process including fast-curing epoxy. In addition, thermoplastic resin-based CFRP and interface enhancement methods to solve the recycling issue of carbon fiber composites were reviewed in terms of materials and processes. To form a perfect matrix-reinforcement interface, which is known as the major factor inducing the excellent mechanical properties of FRP, studies on SRC impregnated with the same matrix in polymer fibers have been reported. The physical and mechanical properties of SRC based on various thermoplastic polymers were reviewed in terms of polymer orientation and composite structure. In addition, a copolymer matrix strategy for extending the processing window of highly drawn polypropylene fiber-based SRC was discussed. The application of CFRP and SRC as lightweight structural materials can provide potential options for improving the energy efficiency of future mobility.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.19-19
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• 2009

최근, 유한한 에너지 자원의 한계와 지구 온난화 등으로 세계의 제조 산업은 새로운 국면을 맞이하고 있으며, 특히, 자동차 산업은 화석연료를 주 에너지원으로 사용한다는 점과 이 연료를 연소시킬 때 발생하는 이산화탄소가 지구 온난화의 주된 원인이 될 수 있다는 점에서 상기 문제들을 해결하기 위한 다양한 방법에 주목하고 있다. 그 중에서 자동차의 생산기술 측면에서 볼 때, 가장 중요한 이슈는 차체 경량화다. 자동차 차체는 자동차를 구성하고 있는 여러 가지 부품 중에서 약 40% 정도의 무게 비율을 차지하고 있기 때문에, 차체 경량화는 연비향상과 이산화탄소 배출가스 감소와 직접적인 관계를 가지고 있다. 다양한 차체 경량화 방법 중에서 가장 쉽게 접근할 수 있는 방법이 경량소재 적용에 의한 경량화 방법이다. 현재, 탄소섬유 강화 플라스틱과 같이 무게 절감 비율을 최대화 할 수 있는 소재들도 개발되어 일부 적용되고 있지만, 일반적으로 차체 경량화 소재로 가장 널리 사용되고 있는 소재는 알루미늄 합금이며, 이에 대한 차체 적용 비율이 점차로 높아지는 추세에 있다. 이에, 본 연구에서는 알루미늄 합금이 차체에 적용되었을 때의 장단점을 살펴보고, 알루미늄 합금을 적용한 차체 생산과정에서 유의해야 될 사항들과 이를 바탕으로 하는 생산성 극대화 방안에 대하여 고찰하였다. 먼저, 기존의 알루미늄 저항 점 용접공법의 단점을 최소화하고 대량생산 체계에 적합하도록 개발된 새로운 개념의 저항 점 용접 시스템에 대해 그 성능과 양산성을 검증하였다. 구리 전극과 알루미늄 피용접물 사이에 프로세스 테이프를 삽입하여 용접하는 이 시스템은 열전도성이 큰 알루미늄 용접부에서 저전류의 조건에서도 효과적으로 균일한 발열현상이 발생하게 하였으며, 전극 팁 드레싱 없이 모든 용접점이 항상 동일한 조건에서 용접이 이루어질 수 있도록 하였다. 용접 조건 설정에 있어서도 용접전류가 통전되는 순간에 전극 가압력을 자유로이 변형시켜 용접부 크랙 발생을 최소화할 수 있음을 확인하였다. 알루미늄의 또 다른 대표적인 접합방법인 아크용접에 있어서는 용접 입열량을 조절하여 용접변형을 최소화 할 수 있는 아크용접 시스템에 대해 양산성과 적용 타당성을 검토하였다. 와이어 송급 방향을 자유자재로 바꿀 수 있는 이 시스템의 특성에 의해 스패터를 최소화하면서 용융금속이 효과적으로 모재에 금속이행 될 수 있음을 확인하였으며, 판재, 압출재, 및 다이캐스팅재 등 다양한 차체 소재에 대한 용접 가능성 및 미그-레이저 하이브리드 용접과의 비교분석을 통하여 차체 박판 용접에서도 최소의 열변형으로 효과적으로 사용될 수 있음을 보였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.147-156
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• 2016

In this paper, optimal designs of bicycle frame were studied for weight reduction of bicycle using carbon-fiber-reinforced plastic (CFRP), glass-fiber-reinforced plastic (GFRP) and Kevlar-fiber-reinforced plastic (KFRP), respectively. Based on the anisotropic properties of FRP material, stacking angle and thickness optimization were performed under the safety reference of European committee for standardization (CEN) to ensure the stability of bicycle frame. Finally, performances of FRP bicycle frame was evaluated by digital logic method based on the optimized results of weight, strength properties and cost. Then, the optimized bicycle frame composed of each FRPs were evaluated and ranked by total performance values.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.629-639
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• 2014

This paper deals with an alternative multi-functional structures by using grid-stiffened composite structure with excellent bending stiffness and lightweight characteristics which is capable of easy embedding of electrical/electronic circuitry into structure. The enhancement of thermal conduction capability is made by the application of pitch-based carbon fiber. The lightweight radiation spot shielding technique is also proposed for multi-functional structures without conventional housing and the effectiveness of selective radiation shielding is validated through the proton irradiation test.