Correlation between Acoustic Emission and Internal Friction in Materials

Abstract

The relationship between acoustic emission and internal friction is investigated during cyclic deformation of copper single- and poly-crystals at intermediate amplitudes. Good agreement between these two phenomena has been demonstrated in all materials tested as long as the stress relaxation occurs uniformly within the sample whereas the difference between them becomes pronounced when strain/fracture localisation takes place. The similarity between acoustic emission and internal friction can be extended to materials deforming without appreciable plastic deformation, such as metal matrix composites where the main source of stress relaxation and strain accumulation is the particle breakage. The significance of the relation between internal friction and acoustic emission for understanding of fundamentals of AE is discussed.