Establishment of traceable measurement standards for acoustic emission energy calibration

Measurement seeks to quantify a measurand by comparing it with a defined standard for that quantity and expressing it in terms of a declared unit of that quantity. Traceability is then the essential property that the result of a measurement must have in order that it can be related to stated standards through an unbroken chain of comparisons. To date acoustic emission (AE) monitoring has been undertaken without proper means of calibration providing traceability and the actual AE measurement results are significantly affected by the experimental layout. As the use of AE monitoring increases, the need for more meaningful measurement to reflect the AE physical process becomes urgent and necessary, and this ultimately requires an absolute calibration for AE measurement systems in-situ. This paper outlines a measurement traceability chain for AE energy calibration using artificial standard AE energy sources generated by the elastic impact of a bouncing-ball, the thermoelastic irradiation of a pulsed-laser, and the excitation of a conical piezoelectric transducer. The basic idea is to provide traceable standard AE energy sources for calibration of AE measurement systems in-situ and make AE measurement traceable. The methods presented here should enable the traceable energy measurement standards to be established for AE.