Calibration of piezoelectric AE sensor sensitivity for longtitudinal wave

Acoustic Emission (AE) technology has been applied widely in petrochemical industry, material testing, aerospace engineering and other fields, and AE sensor is an indispensable component used to collect information in AE testing. Most AE sensors are piezoelectric transducers. The calibration of piezoelectric AE sensors is the premise of AE quantitative testing. Longitudinal wave sensitivity is an important indicator when AE testing technology is applied in thick-walked vessel and large concrete construction. The paper establishes comparison and reciprocity methods to research the calibration of piezoelectric AE sensor for longitude wave. In the comparison calibration, laser interferometer is used to measure the normal displacement and velocity on the surface of glass block where AE sensor was placed. This velocity is considered as the referenced velocity of the AE sensor. Then the output voltage of the AE sensor with the same simulation is measured. Finally, the sensitivity of the AE sensor can be calculated. In the reciprocity calibration, a block of steel is considered as propagation medium. Two sensors used to send and receive acoustic signal respectively are fixed on opposed sides of the steel. The computer controls the signal generator to send pulse signal to the transmitter and controls oscillograph to acquire electric signal of the receptor. Finally, sensitivities of different frequency can be calculated. Comparison results of the two methods show that the frequency responses of sensitivities for longitudinal wave are almost consistent. But there are some differences in amplitude between the two methods. Besides, the amplitudes fluctuate widely in adjacent frequency. The reason of these phenomena will be the focus in future research.