USE OF ACOUSTIC EMISSION DURING TEARING INSTABILITY OF ELASTIC-PLASTIC CRACK GROWTH.

The initiation and growth of flaws leading to structural instability give rise to acoustic emission that can provide non-destructive evaluation of the severity of the defect growth. This paper describes the research carried out to correlate the characteristics of the acoustical signals to the fracturing processes taking place at the crack tip under increasing load and, subsequently, real-time monitoring of the defect. Experimental data for many different kinds of alloy steels tested over a range of temperatures have been used for the development of a normalized resistance curve. This experimental key curve can be used concurrently with the acoustic emission tests for an assessment of the onset of crack initiation.