Acoustic emission monitoring of fatigue crack propagation

The monitoring of fatigue crack propagation in steel and welded steel compact tension and T-section girder test specimens, using an advanced acoustic emission system with accurate source location, is described. The compact tension test specimens were subjected to load ratios of 0.1, 0.3, 0.5 and 0.7 while the T-section girders were subjected to a load ratio of 0.3. Located acoustic emission events were filtered for a narrow band containing the fatigue crack, and separated for different regions of the applied load range. The test results indicate that acoustic emission count rates, for small percentages of the applied load range close to the peak load, show reasonable correlation with crack propagation rates. Based on these correlations it may be possible to predict the remaining service life of fatigue damaged structures from the results of short term acoustic emission monitoring. (C) 2002 Elsevier Science Ltd. All rights reserved.