Acoustic emission (AE)

Acoustic emission (AE) is the formation of a pressure wave upon the release of energy accumulated in a solid body. This phenomenon can be produced by mechanical stress and by changes in the thermal state or crystal structure of the body. Acoustic events similar to true acoustic emission are observed on metallic surfaces when the surface is in contact with metals, fluids or gases, and when ambient sound (noise) is introduced into the mechanical structure and is transmitted as a pressure wave.

The maximum stress tolerable by a metal structure can be determined by the analysis of acoustic emission events accompanying internal friction, elastic deformation, cracking and crack spreading, because there is a direct quantitative relationship between acoustic events and material damage.