Acoustic emission due to nucleation of a microcrack in the proximity of a macrocrack

Acoustic emission generated by the nucleation of a microcrack in the proximity of a macrocrack is discussed in this paper. On the basis of some simple approximations the acoustic emission from a crack-opening event is directly related to its crack-opening volume as a function of time. It is shown that the nucleation of a microcrack in the immediate vicinity of a macrocrack generates additional crack-opening volumes for both the macrocrack and the microcrack, whose signals tend to be much larger than those that would emanate from a nucleating solitary microcrack.