Characterization of Acoustic Emission Waveforms from Fracture Events

The separation of crack growth signals from other extraneous sources is of fundamental importance for the advancement of acoustic emission techniques. As a step in that direction, this research seeks to quantitatively determine and characterize the waveform characteristics of acoustic emission signals from fracture sources. These fracture sources include fatigue crack growth events (Mode I, II and mixed mode) as well as other sources of micro damage. The experimental portion of this work uses a four channel data acquisition system that captures and digitizes the entire acoustic emission waveform. Laboratory specimens examined include a notched tension specimen as well as a circular torsion fatigue specimen. The measured acoustic emission waveform characteristics (such as amplitude and frequency spectrum) are correlated with the observed crack growth