ABSTRACT
A fatigue crack generates an acoustic emission event through the rapid release of elastic energy with each step in the crack growth process. To measure such a phenomenon, an array of three or more acoustic emission sensors are placed on the fracture critical bridge member (Figure 3). Measuring the time of arrival of AE events then enables the localization of the active flaw within the array using standard Time Difference of Arrival (TDoA) techniques. Acoustic emission signal features may be used to estimate fatigue crack growth rates. Useful AE signal features include amplitude, rise-time, counts, signal duration, and energy.
