Acoustic Emission (AE) is simply the stress waves, in the frequency range of ultrasound usually between 20 kHz and 1 Hz, generated in the materials due to deformation, crack initiation and growth, crack opening and closure, dislocation movement, twining and phase transformation, fiber breakage and delamination. 

Advantages

• Ability to detect a range of damage mechanisms including, but not limited to, fibre breakages, friction, impacts, cracking, delamination and corrosion in their early stages, before they become significant issues.

• Can be conducted during operation, during qualification (proof) testing or development testing.

• Can locate damage sources and can be differentiate these based on acoustic signatures.

• Global monitoring of a structure

• Assesses the structure or machine under real operational conditions

• A non-invasive method

• Operational in hazardous environments, including high temperatures, high pressures and corrosive and nuclear environments

• Can be conducted remotely

• Can detect damages in defects that are difficult to access with conventional non-destructive testing techniques