Correlation of crack propagation and acoustic emission rates

An advanced acoustic emission (AE) system DiSP-4 has been used to monitor fatigue crack growth in steel, aluminium and welded steel compact tension (CT) specimens subjected to load ratios of 0.1, 0.3 and 0.5. Recorded AE data was filtered for a 10. mm band containing the fatigue crack. Acoustic emission counts for the 10 mm band were separated and analysed for different regions of the applied load range. It was found that AE count rates close to the peak load Shaw reasonable correlation with crack growth rates while AE count rates related to the entire load range show little correlation with crack growth rates. A reduction in the AE count rate appears to be associated with rapid crack growth and imminent failure.