Detection of Critical Fatigue Cracks in Steel Bridge Materials with Remote Acoustic Emission Monitoring

Catastrophic failure of steel bridge components can occur if the fatigue cracks reach critical levels. The purpose of the study described is to characterize the acoustic emission (AE) corresponding to crack extension from the stable to the unstable stage in steel bridge material. AE monitored fatigue tests were conducted using specialized compact tension (CT) specimens made of ASTM A572G50. A combined approach involving Swansong II filters and investigation of waveforms is employed in the discrimination of AE signals caused by cracks or noise. This approach is appropriate for data filtering and interpretation of sparse data as may be expected from field tests where wireless monitoring is essential. The results indicate that AE parameters from reduced datasets can provide warning for critical fatigue cracks under different test conditions. The transition of fracture mechanisms is reflected in the reduced AE dataset.