Modeling Time of Arrival Probability Distribution and TDOA Bias in Acoustic Emission Testing

Abstract

Acoustic emission testing is widely used by industry to detect and localize faults in structures, but estimated source positions often show significant bias in real tests as a consequence of Time Difference of Arrival (TDOA) bias. In this work, a model for TDOA bias is developed considering the time of arrival was estimated using the fixed threshold algorithm, as well as theoretical upper and lower bounds for it. In addition, we derive the time of arrival probability distribution function in terms of the noise distribution and acoustic emission waveform for the fixed threshold algorithm, showing that, contrary to usual practice, it in general cannot be well approximated by a Gaussian distribution.