An Ultrasonic Technique for Detection of the Onset of Fatigue Damage.
Annual rept. 1 Mar 72-28 Feb 73,
JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICS AND MATERIALS SCIENCE
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The purpose of the research is to develop an ultrasonic techniques for the detection of the onset of fatigue damange. Particular emphasis is placed on the use of ultrasonic attenuation measurements as a continuous monitor of fatigue damage during cyclic testing of metal specimens. Efforts to date have indicated that the history of attenuation during fatigue of the specimen provide an index as to the onset of failure. Ultrasonic attenuation measurements made simultaneously with fatigue tests on aluminum bars give an early warning of eminent fracture. Such a warning occurs much earlier than detection of energy reflected from a crack by conventional ultrasonic techniques. This is true for specimens which were initially defect free and for those which initially had structural defects. A systematic comparison is being made between ultrasonic attenuation and other ultrasonic techniques, principally surface wave techniques and acoustic emission techniques. Author
- Test Facilities, Equipment and Methods