The phenomenon that local sources in materials quickly release energy to produce transient elastic waves is called acoustic emission (AE), sometimes called stress wave emission. The deformation and crack propagation of materials under stress are important mechanisms of structural failure. This kind of source directly related to deformation and fracture mechanism is called acoustic emission source. Another kind of elastic wave source, such as fluid leakage, friction, impact and combustion, is not directly related to deformation and fracture mechanism, and is called other or secondary acoustic emission source.
At present, the development direction of acoustic emission instrument is full digital full waveform acoustic emission instrument, which is characterized by that hardware only collects the waveform of digital acoustic emission signal, and other work such as parameter generation, filtering and even threshold function can be completed by software in real time or afterwards. Acoustic emission technology is gradually moving towards waveform signal analysis, and the full waveform acoustic emission instrument will gradually replace the traditional parametric acoustic emission instrument.