Correlation of Barkhausen effect type measurements with acoustic emission in fatigue crack growth studies

Discontinuous changes in the magnetization of a ferromagnetic sample similar to the rapid changes in magnetization which take place in the Barkhausen Effect are caused by the propagation of a fatigue crack. These changes were detected through induced voltages on a pick-up coil surrounding the specimen, which can be quantitatively related to the crack growth. Simultaneous acoustic emission measurements confirmed that the magnetization changes were due to the fatigue crack. In some cases the resolution of the Barkhausen technique is superior to the resolution of acoustic emission measurements.