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조인식(Insik Cho),이창순(Changsoon Lee),편영식(Youngshik Pyoun),박인규(Ingyu Park),김병훈(Byounghoon Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
An ultrasonic fatigue testing device, capable of fracturing the tested materials at an ultrasonic frequency of 20 ㎑ is demonstrated. Such a testing device, operating at high frequencies, not only reduces the testing time to far less than that of conventional testing machines, but may also better simulate extremely high-frequency loading and the strong influence of strain rate on the fatigue behavior of the tested materials. This makes the development of an ultrasonic fatigue testing device for testing materials is an important endeavor. Very high cycle fatigue of Al 6061-T6 alloy was investigated using accelerated ultrasonic fatigue testing at 20 ㎑ under completely reserved loading conditions (R=-1) on a piezoelectric machine which was developed by DaeJin Science Co., Ltd. In this study, the ultrasonic fatigue tests were conducted in the range of 10?~10? fatigue fracture cycles, while testing maximum amplitude stress (S) was 117.76 ㎫ at gigacycle. Scanning electron microscopy (SEM) analyses were carried out and the results show that three crack fracture modes were observed.