Acoustic emission during fatigue of Ti-6Al-4V : incipient fatigue crack detection limits and generalized data analysis methodology

• Published in: Journal of materials science Vol. 27; no. 12; pp. 3133 - 3142
• Main Authors: KOHN, D. H, DUCHEYNE, P, AWERBUCH, J
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 15.06.1992
• Subjects: Applied sciences; Exact sciences and technology; Fatigue; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Titanium alloy; Data analysis; Detection limit; Mechanical characteristic; Acoustic emission; Fatigue; Titanium Aluminium Vanadium Alloys; Experimental study; Crack initiation; Fatigue crack; Crack propagation
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/BF01116003

The fundamentals associated with acoustic emission monitoring of fatigue crack initiation and propagation of Ti--6Al--4V were studied. Acoustic emission can detect and locate incipient fatigue crack extensions of approx 10 mu m. The technique therefore can serve as a sensitive warning to material failure. There are three distinct stages during which acoustic emission is generated. These stages are: crack initiation, slow crack propagation and rapid crack propagation. The distinction between the stages is based primarily on the rate of acoustic emission event accumulation. These three stages of acoustic emission correspond to the three stages of the failure process that occurs during fatigue loading. That is, changes in acoustic emission event rate correspond to changes in crack extension rate. Acoustic emission event intensities are greater during crack initiation than during slow crack propagation and greatest during rapid crack propagation. In a given fatigue cycle, event intensities increase with increasing stress and most high-intensity events occur near or at the maximum stress. Acoustic emission may therefore be used with confidence to detect, monitor and anticipate failure, in real-time.