Traceability of acoustic emission measurements using energy calibration methods

Passive acoustic emission (AE) methods are becoming useful tools for integr ity assessment of structures, monitoring of industrial processes and machin es, and materials characterization. Unfortunately there are no measurement standards for estimating the absolute strength of the AE sources. The lack of standardization makes it very difficult to compare the results obtained in different laboratories or on different structures, and to obtain meaning ful repeatability of measurements. Therefore, current methods only give a q ualitative rather than quantitative indication of the change of state of st ructure or process. This communication outlines a way of calibrating AE tra nsducer systems in situ using a pulsed-laser-generated thermoelastic AE ene rgy source or a bouncing-ball-generated elastic impact AE energy source. Th e methods presented here should enable traceable measurement standards to b e established for AE.