Methodical approach to the experimental acoustic-emission evaluation of the crack resistance of structural materials

We develop a general approach to the determination of the characteristics of crack resistance of structural materials by the method of acoustic emission. This approach includes the procedure of selection of acoustic signals from cracks and the proper choice of the most efficient parameters of acoustic signals, the operating frequency of the receiving circuit of an acoustic-emission device, and the location of an acoustic-emission transducer. It is shown that, in the process of propagation of a crack, acoustic radiation is directed and the frequency band of emitted acoustic signals becomes narrower in the stage of subcritical crack growth.