Influence of The Passband of Frequency Filters on the Parameters of Acoustic Emission Pulses

Abstract

To study the effect of the passband of a digital filter on the nature of the attenuation of the amplitude of an acoustic emission (AE) pulse and on the change in the group velocity of a wave packet in the near zone of up to 300 mm from the radiation source, studies were conducted on a multilayered polymer-composite-material (PCM) panel and an AMG-2 aluminum alloy plate with a thickness of 6 mm. In the course of the experiments, it has been established that narrowing the passband of the digital filter from 30–500 to 100–200 kHz can significantly affect the accuracy of the coordinate location of AE-event radiation sources situated near AE transducers, at a distance of less than 100 mm. As the passband of the digital filter narrows and the low- and high-frequency components of the spectrum are cut off, the wave front of the recorded pulse becomes more gently sloping, resulting in an increase in the difference of arrival times (DAT) of pulses to the AE transducers and in a decrease in the calculated group velocity of the wave packet. The error arising in this case is greater than the passband of the filter applied.