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Fatigue life prediction method for contact wire using maximum local stress
김용석,이기원,Li Haochuang,석창성,구재민,권삼영,조용현 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1
Railway contact wires supplying electricity to trains are exposed to repeated mechanical strain and stress caused by their own weightand discontinuous contact with a pantograph during train operation. Since the speed of railway transportation has increased continuously,railway industries have recently reported a number of contact wire failures caused by mechanical fatigue fractures instead of normal wear,which has been a more common failure mechanism. To secure the safety and durability of contact wires in environments with increasedtrain speeds, a bending fatigue test on contact wire has been performed. The test equipment is too complicated to evaluate the fatiguecharacteristics of contact wire. Thus, the axial tension fatigue test was performed for a standard specimen, and the bending fatigue life forthe contact wire structure was then predicted using the maximum local stress occurring at the top of the contact wire. Lastly, the testedbending fatigue life of the structure was compared with the fatigue life predicted by the axial tension fatigue test for verification.
홍석우,석창성,안상수,Haochuang Li,김정기,고상진,구재민 한국정밀공학회 2013 International Journal of Precision Engineering and Vol.14 No.2
Recently, the use of Carbon Fiber Reinforced Plastic (CFRP) composite , instead of metal materials, has increased in fields that have high demand for both lightweight and high specific strength materials, such as aircraft and automobile. Composites show different characteristics according to temperature and fiber array direction. Under the operating condition, the fuselage of an aircraft is often exposed to impacts from birds, hail etc. Therefore, Charpy impact fracture characteristics of the CFRP composite according temperature and fiber array direction need to be estimated to ensure aircraft safety. In this paper, after the Charpy impact tests,fractured surfaces were analyzed to estimate the impact fracture characteristics of the CFRP composite by SEM.
Bending Fatigue Life Evaluation of Cu-Mg Alloy Contact Wire
Guo Zhen,석창성,김용석,Li Haochuang,구재민,이기원,권삼영 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.7
Contact wire is one of the most important components used to supply electricity to railway vehicles which equipped with apantograph. When the speed of electric vehicle is not as high as now, the failure of contact wire caused by friction and wear behaviorsof carbon strip/contact wire were considered more important. But the fatigue fracture become more and more important for the failureof contact wires on account of several fatigue fractures happened while the speed of electric vehicle increase continuously. A bendingfatigue tester simulating the working conditions of contact wires developed by Kang and etc has been used to evaluate the fatiguecharacteristic of pure copper and Cu-Sn alloy contact wires. In this study, this bending fatigue tester also is used to evaluate thefatigue characteristics of Cu-Mg alloy contact wire which developed for 400km/h high speed rail in Korea. Test result is alsocompared with the result of Kang's research on pure copper contact wire. Finally, in order to evaluate the fatigue life of contact wiresfor any mean stress, the relationships between plastic strain and fatigue life were abstained for two kinds of contact wires combinedthe FE analysis.