The Nature of Acoustic Emission during Deformation Processes in Metallic Materials

Abstract

The theoretical foundation of the method of acoustic emission (AE) was established in the pioneering studies by V. Natsik and his colleagues, which were published in the 1960s–1980s. The source functions corresponding to elementary dislocation mechanisms of plastic deformation and fracture were calculated based on continuum dislocation dynamics. The results remain up to date. Despite the existing experimental difficulties in verifying some of the basic formulations, these works clearly demonstrated the differences between potential sources of acoustic emission in materials. Based on these fundamental premises, statistical methods for recognizing the AE mechanisms, utilizing spectral and cluster analysis of AE time series, were recently proposed. This brief communication reviews theoretical models of AE sources, as well as some key experimental findings, to provide insights into the nature of the acoustic emission peak in the early stages of plastic deformation of metals. The methods for analyzing the AE signal and recognizing the AE sources are also discussed.