

Ultrasonic Guided Wave SHM for Probabilistic Fatigue Crack Growth Prognostics
Abstract
Ultrasonic guided waves are used to characterize the size of a fatigue crack growing from a fastener hole in a plate structure based on a transmission coefficient ratio. The measurement uses the S0 Lamb wave mode and two wave paths from a single transmitter; a test path that is partially obstructed by the hole, and a reference path that is effectively unaltered by fatigue crack growth. Thus, three piezoelectric disk transducers are employed. Results from four specimens are presented, and with the help of uncertainty modeling described in a companion paper, the bounds on predicted remaining useful life are determined.