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Understanding Acoustic Emission Testing- Reading 1 Part B-A

Understanding Acoustic Emission Testing- Reading 1 Part B-A

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Barkhausen Noise<br />

Barkhausen noise can be heard if a coil of wire is wrapped around the sample<br />

undergoing magnetization. Abrupt movements in the magnetic field produce<br />

spiking current pulses in the coil. When amplified, the clicks can be compared<br />

to Rice Krispies or the crumbling a candy wrapper. The amount of<br />

Barkhausen noise is influenced by material imperfections and dislocations<br />

and is likewise dependent on the mechanical properties of a material.<br />

Currently, materials exposed to high energy particles (nuclear reactors) or<br />

cyclic mechanical stresses (pipelines) are available for nondestructive<br />

evaluation using Barkhausen noise, one of the many branches of AE testing.<br />

Charlie Chong/ Fion Zhang

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