Application of System Identification to the Absolute Calibration of Acoustic Emission Signals

Abstract

This paper studies the absolute calibration of acoustic emission signals. The experiments were conducted on a thin plate. Fracture of a glass capillary was adopted to generate a vertical force with a unit-step source function, and an NBS conical transducer was used to record the surface response. It is found that the output of the conical transducer contains surplus wiggles and exhibits amplitude decay. The system identification method is introduced to determine the dynamic model of the system. Calibration using the system model successfully recovers the amplitude and greatly suppresses the surplus wiggles. The method is further improved by subtracting the characteristic curve of the wiggles from the experimental data before the system identification approach is carried out.