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[재료부문] 열피로가 부가된 Carbon-Epoxy 복합재료의 탄성계수 변화에 관한 연구
이동식(D.S.Lee),박세만(S.M.Bahk) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Applications of composite materials have been increased in automotive and aircraft industries prompting active researches. The carbon-epoxy composite one of widely accepted composite materials. is selected to study its thermal characteristics. During thermal fatigue processes composed of repeated cooling and heating variations of elastic constants are investigated to understand thermal effects on the carbon-epoxy composite. In this investigation values of E show amount of increases depending on number of cycles of the thermal fatigue processes whereas values of G do not indicate noticeable changes. Also in cases of E and G their values decrease to a certain extend in initial stages after applications of thermal fatigue processes. However. the number of cycles of the applied thermal fatigue processes does not seem to affect their values.
[재료] 열충격이 부가된 Carbon-Epoxy 복합재료의 탄성계수 변화에 관한 연구
이동식(D.S.Lee),박세만(S.M.Bahk) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1999 No.11_2
Composite materials have been recognized for continuing increase in their usages and applications in automotive and aircraft industries. This trend inevitably calls for extensive researches in the materials. Carbon-epoxy' composites. one of the foremost composites are selected for investigate ions to determine their thermal characteristics. Being subjected to thermal shocks consisting of repeated heatings and coolings the carbon-epoxy composites show variations in elastic constants revealing the thermal nature of the composites. In this study the values of E₁are observed to increase and the values of G13 are observed to decrease as thermal shocks are applied. However the values of E₁, E₂and G12 another elastic constant. G23 exhibits very different behavior with increasing temperatures.
이동식(D. S. LEE),이현욱(H. W. LEE),정영우(Y. W. Jeong),양홍익(H. I. Yang),안길영(K. Y. Ahn) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Recently, high reliability of electrical power system is required. Accordingly, for the protection of the power systems used circuit breakers are required high reliability. Nowadays general interruption time of circuit breaker is 3~5 cycle, but recently, to meet the needs of the high reliability, research on high speed circuit breaker has been made. The studies of high speed circuit breaker consist of research of high speed protection relay and high speed circuit mechanism. In this study, we proposed high speed mechanism with hybrid type mechanism, which consists of conventional spring mechanism and Thomson coil actuator.
Carbon-Epoxy 복합재료의 열피로 거동에 관한 연구
이동식(D.S.Lee),박세만(S.M.Bark),이재혁(C.H.Yi),김형삼(H.S.Kim) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_2
An experimental apparatus is contrived and constructed for measurements of resonance frequencies to determine dynamic elastic constants of composite materials. Materials selected for testing are carbon/epoxy composites that are well accepted in automotive and aerospace industries. Specimens prepared from the composites are subjected to thermal fatigue cyclings that are composed of repeatedly exposing specimens alternately between room temperature and desired elevated temperatures. The cycling temperatures are systematically raised with an increment of 20°C up to 200°C at which physical changes in the specimens are visible. The heat-treated specimens are tested to measure resonance frequencies for torsional and flexural vibrations, respectively which are subsequently utilized to evaluate the elastic constants E₁, E₂, G_23, and G_13 of the composites at elevated temperatures. Also, investigations are conducted to discern any effects on the elastic constants of the composites due to the thermal fatigue cyclings. The elastic constants E₁ exhibits maximum around 100°C and continuously decrease afterwards whereas E₂ does not show a consistent pattern of behavior or variations in its measured values.<br/>