Ultrasonic and Acoustic Emission Detection of Fatigue Damage.
Abstract
The purpose of the present research is to optimize existing ultrasonic and acoustic emission techniques and to investigate new ones for early detection of fatigue damage in aluminum alloys used in aircraft construction. An ultrasonic pulse-echo system was used during fatigue cycling to record conventional A-scan wave forms as well as to monitor ultrasonic attenuation on 7075-T651 aluminum alloy specimens possessing different surface conditions. In addition, acoustic emission signals were recorded simultaneously with the ultrasonic measurements on each test specimen using two different acoustic emission systems. The task of correlating evidence of cumulative fatigue damage and acoustic emission data was approached by the use of long term true-rms averaging of the system output and frequency domain analysis of acoustic emission signals recorded at selected intervals throughout the test. The integrity of the data was verified by independent electronic testing of the instrumentation, in situ eddy current and visual inspection, and metallographic examination. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1979
- Accession Number
- ADA079277
Entities
People
- C. L. Friant
- R. E. Green Jr.
- S. E. Fick
- S. R. Buxbaum
Organizations
- Johns Hopkins University