Acoustic emission

[5][6] The AE method makes it possible to study the kinetics of processes at the earliest stages of microdeformation, dislocation nucleation and accumulation of microcracks.

[5][6] Up to this size, the crack grows very slowly (sometimes for decades) through a huge number of small discrete jumps accompanied by AE radiation.

Acoustic emission is the transient elastic waves within a material, caused by the rapid release of localized stress energy.

The three major applications of AE techniques are: 1) source location – determine the locations where an event source occurred; 2) material mechanical performance – evaluate and characterize materials and structures; and 3) health monitoring – monitor the safe operation of a structure, for example, bridges, pressure containers, pipelines, etc.

A significant expansion of the capabilities and an increase in the reliability of the AE diagnostic method is provided by the use of statistical methods for analyzing random event streams (for example, the random Poisson stream model)[5][6] The frequency domain representation of a signal obtained through Fast Fourier transform (FFT) provides information about the signal's magnitude and frequency content.

In materials under active stress, such as some components of an airplane during flight, transducers mounted in an area can detect the formation of a crack at the moment it begins propagating.

[15] AE sensing can potentially be utilised to monitor the state of health of lithium-ion batteries, particularly in the detection and characterisation of parasitic mechano-electrochemical events, such as electrode electrochemical grinding, phase transitions, and gas evolution.

Applications where acoustic emission monitoring has successfully been used include detecting anomalies in fluidized beds and end points in batch granulation.