Crack Growth Acoustic Emission Research Articles

Analysis of Acoustic Emissions from a Steel Bridge Hanger

A steel bridge hanger with three fatigue cracks was monitored for acoustic emission (AE) using combined source location, strain gauge monitoring, and waveform analysis. AE activities from all three cracks were clearly identified and classified as crack growth or noise signals using location, strain magnitude, position on strain cycle, and uniqueness of waveforms as the primary criteria. A vast majority of AE from the cracks was found to be due to crack face rubbing and the crushing of corrosion products between the crack faces while limited crack growth emissions were detected. Results from laboratory tests on A588 compact tension specimens under variable-amplitude tension-tension fatigue loading were used to aid in interpreting AE data from the hanger. Crack growth AEs from these tests were detected only on overload cycles mostly above 92% of the maximum load while AE due to crack face rubbing occurred throughout the load cycle.

Analysis of Acoustic Emissions from a Steel Bridge Hanger

A steel bridge hanger with three fatigue cracks was monitored for acoustic emission (AE) using combined source location, strain gauge monitoring, and waveform analysis. AE activities from all three cracks were clearly identified and classified as crack growth or noise signals using location, strain magnitude, position on strain cycle, and uniqueness of waveforms as the primary criteria. A vast majority of AE from the cracks was found to be due to crack face rubbing and the crushing of corrosion products between the crack faces while limited crack growth emissions were detected. Results from laboratory tests on A588 compact tension specimens under variable-amplitude tension-tension fatigue loading were used to aid in interpreting AE data from the hanger. Crack growth AEs from these tests were detected only on overload cycles mostly above 92% of the maximum load while AE due to crack face rubbing occurred throughout the load cycle.

Acoustic emission from reinforced concrete beams

The acoustic emission behaviour of reinforced concrete beams under flexure load was studied. Useful correlation was established between the acoustic emission activity under loading state and crack growth in the reinforced concrete beams. Three different acoustic emission rate regions were observed during the flexural loading. Crack initiation and crack propagation were detected monitoring the acoustice mission. The zone ef crack initiation and development can be identified from the acoustic emission event-location plot, showing major acoustic emission concentration ureas. Repetitive loading showed that the Kaiser effect was valid only up to 80% of the ultimate load level, with norelaxation phenomenon , for test intervals less than 2h. Crack growth acoustic emission burst event signals were found to be of higher amplitude compared with those due to deformation. The accumulated number of burst events of these high-amplitude emissions, monitored by the use of a high threshold, showed good correlation with the total cracked surface.