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A Study on the Load and Deformation of Race Carbon Bicycle Frame for Improved Athletic Performance
Ung Jae Choi(최웅재),Seung Ho Choi(최승호),Yong Sun Kim(김용선),Seong Min Yun(윤성민),Hong Gun Kim(김홍건) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.1
As the industry develops and quality of life increases, the concept of leisure is also changing. Bicycling is a healthy sport for exercising while enjoying nature, facilitating the enjoyment of a healthy life. As a result, the awareness surrounding bicycles has increased, and so has the interest in lighter and more luxurious carbon bikes. The number of domestic companies producing carbon bicycles frames is nil. In this study, we analyze the frames of existing foreign brands and analyze the deformation and stress concentration area according to the load of the frame, using the finite element analysis. In addition, we set up the range of stiffness based on the content of the structural analysis, to localize the carbon bicycle frame and famous foreign products, and compare the prototype with the stiffness by using bicycle molds for track races.
카본 자전거 프레임 소재의 적층 패턴에 따른 프레임 강성 연구
최웅재(Ung-Jae Choi),김홍건(Hong-Gun Kim),곽이구(Lee-Ku Kwac) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.6
The notion of leisure has changed with industrial development and improvement in life quality. Bicycling is a healthy sport; it is an exercise performed while enjoying nature. There have been many changes in the materials that are used to manufacture the bicycle frame. Iron and aluminum have been mainly used in bicycle frames. However, carbon-based materials are lighter and stronger than metal frames. The bicycles made of carbon composite changes frame rigidity depending on the direction of the carbon sheet sacking angle. We study the direction of composite material and how they affect the stiffness of frames based on the stacking angle.
유한요소해석을 이용한 CFRP 자전거 프레임의 설계 및 성능 평가
이용성(Yong-Sung Lee),신기훈(Ki-Hoon Shin),정성균(Seong-Kyun Cheong),최웅재(Ung-Jae Choi),김영근(Young-Keun Kim),박경래(Kyung-Rea Park),김홍석(Hong Seok Kim) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.1
최근 경량 자전거에 대한 요구가 지속적으로 증가함에 따라 탄소섬유 복합재료가 자전거 프레임 및 부품 제작에 널리 활용되고 있다. 복합재료는 일반적인 등방성 재료와는 달리 적층판의 방향과 순서에 따라 그 구조적인 특성이 변화하기 때문에 복합재료 자전거의 디자인을 검증하기 위해서는 구조 해석을 수행하는 것이 필수적이다. 본 연구에서는 CFRP 소재를 적용하여 자전거 프레임을 설계하였고, 유한요소해석을 통하여 그 구조적 성능을 분석하였다. 다양한 적층 순서와 하중조건 하에서 섬유와 매트릭스의 파손지수를 측정함으로써 복합재의 적층 조건이 자전거의 구조 강도에 미치는 영향을 분석하였다. 또한 취약 부분은 추가적인 복합재 적층판을 이용하여 보강함으로써 자전거 프레임의 구조적 안전성을 확보할 수 있었다. With the continuing demand for lightweight bicycles, carbon fiber composite materials have been widely used in manufacturing bicycle frames and components. Unlike general isotropic materials, the structural characteristics of composite materials are strongly influenced by the staking directions and sequences of composite laminates. Thus, to verify the design process of bicycles manufactured using composites, structural analysis is considered essential. In this study, a carbon-fiber-reinforced plastic (CFRP) bicycle frame was designed and its structural behavior was investigated using finite element analysis (FEA). By measuring the failure indices of the fiber and matrix under various stacking sequences and loading conditions, the effect of the stacking condition of composite laminates on the strength of the bicycle structure was examined. In addition, the structural safety of the bicycle frame can be enhanced by reinforcing weak regions prone to failure using additional composite laminates.
유한요소법을 이용한 CFRP 자전거 포크의 취약부 탐색 및 안전성 확보 방안 연구
이수영 ( Su Yeong Lee ),이남주 ( Nam Ju Lee ),최웅재 ( Ung Jae Choi ),김홍석 ( Hong Seok Kim ),신기훈 ( Ki Hoon Shin ),정성균 ( Seong Kyun Cheong ) 한국안전학회(구 한국산업안전학회) 2016 한국안전학회지 Vol.31 No.6
A bicycle is one of the most popular sporting goods in view of a sport activity and a human health. Metallic materials such as steel, aluminum, etc. were mainly used to the bicycle fork in the past. Nowadays, the carbon fiber reinforced composite materials are widely used to the manufacturing of a bicycle fork to reduce the weight and to increase the efficiency. Safety is a most important design parameter of a bicycle fork even if the weight and cost reduction are important. Bicycle failure may happen at the critical spot of a bicycle fork and cause the accident. In this paper, the composite bicycle fork will be analyzed to secure the safety and detect a critical spot by using the finite element method with Tsai-Wu failure criterion. The stress data were obtained for the laminated composites with various number of plies and fiber orientation under the bending load. Thus, design concept of a bicycle fork was proposed to secure the safety of a bicycle. The finite element analysis results show that the connection area between a steer tube and a fork blade is critical spot, and 75 or more layers of 0 degree are needed to secure the safety of a bicycle fork. Key Words : bicycle forks, carbon fiber reinforced composite materials, finite element method, strength reinforcement, Tsai-Wu composite failure criterion
이용성(Yong-Sung Lee),김홍석(Hong Seok Kim),정성균(Seong-Kyun Cheong),최웅재(Ung-Jae Choi),김영근(Young-Keun Kim),박경래(Kyung-Rea Park),신기훈(Ki-Hoon Shin) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.1
컴파운더 보우는 리커브 보우와 비교하여 케이블 및 캠 풀리로 구성되는 지레시스템을 사용하여, 궁사가 보우를 최대 위치로 당기기 위해 필요로 하는 힘을 줄이는 동시에 더 많은 에너지를 축적할 수 있도록 해준다. 지금까지 컴파운더 보우의 효율 및 성능을 향상시키기 위해 경험적인 방법에 기초하여 많은 특허가 제안되었지만, 해석적인 방법에 대한 연구는 별로 없었다. 그러므로 본 연구에서는 컴파운더 보우 지레 시스템의 기구학적인 해석을 위한 방법을 제안하여 지레시스템의 캠 형상 및 보우 날개의 재질변화에 따른 효과를 설계자가 쉽게 예측할 수 있도록 하고자 한다. Compound bows use levering systems consisting of cables and cam pulleys to bend limbs that are much stiffer than those of recurve bows, thus storing more energy while requiring less force for the archer to hold the bow at a fully drawn position. Many patents have thus far been proposed to improve the efficiency and performance of compound bows through empirical methods, whereas only a few analytical methods have been proposed. In this light, this paper presents a method for the kinematic analysis of levering systems in compound bows so that a designer can easily predict the effects of changes in the cam profiles and limb materials.