Prediction of low-cycle fatigue-life by acoustic emission—1: 2024-T3 aluminum alloy, and —2: 7075-T6 aluminum alloy
- Ben-Gurion Univ. of the Negev, Beer Sheva (Israel). Materials Engineering Division
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials and Molecular Research Division
1: In this paper, low-cycle fatigue tests were conducted by tension-tension until rupture, on a 2024-T3 aluminum alloy sheet. Initial crack sizes and orientations in the fatigue specimens were found to be randomly distributed. Acoustic emission was continuously monitored during the tests. Every few hundred cycles, the acoustic signal having the highest peak-amplitude, was recorded as an extremal event for the elapsed period. This high peak-amplitude is related to a fast crack propagation rate through a phenomenological relationship. The extremal peak amplitudes are shown by an ordered statistics treatment, to be extremally distributed. The statistical treatment enables the prediction of the number of cycles left until failure. Predictions performed a posteriori based on results gained early in each fatigue test are in good agreement with actual fatigue lives. Finally, the amplitude distribution analysis of the acoustic signals emitted during cyclic stress appears to be a promising nondestructive method of predicting fatigue life. 2: In this paper, low cycle high stress fatigue tests were conducted by tension-tension on an Alclad 7075-T6 aluminum sheet alloy, until rupture. Initial crack sizes and orientations in the fatigue specimens were randomly distributed. Acoustic emission was continuously monitored during the tests. Extremal peak-amplitudes, equivalent to extremal crack-propagation rates, are shown to be extremally Weibull distributed. The prediction of the number of cycles left until failure is made possible, using an ordered statistics treatment and an experimental equipment parameter obtained in previous experiments (Part 1). The predicted life-times are in good agreement with the actual fatigue lives. Finally, the amplitude distribution analysis of the acoustic signals emitted during cyclic stress has been proven to be a feasible nondestructive method of predicting fatigue life.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE
- Contributing Organization:
- Ben-Gurion Univ. of the Negev, Beer Sheva (Israel)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 1068981
- Report Number(s):
- LBL-10764
- Journal Information:
- Engineering Fracture Mechanics, Vol. 15, Issue 3-4; ISSN 0013-7944
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
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