Nondestructive Evaluation of the Evolution of Fatigue Damage

초록

Although the early stage of fatigue damage is a process governed by microscopic features such as moving dislocations or grain boundary, fatigue damage at a detectable level manifested by microcracks, or with more generalized terms, short fatigue cracks. Short cracks are in the size range from several micrometers to a millimeter, which is about the lower bound of the detectability of conventional nondestructive testing. Various measurement techniques, both destructive and nondestructive, have been devised for detecting short fatigue cracks. This paper will review the existing methods of nondestructive testing and introduce a new version of signal processing, so-called wavelet de-noising which may enable acoustic emission be an effective means to determine the onset of fatigue damage.