Acoustic Emission Source Location Using Lamb Wave Modes

Abstract

This paper describes the development of a technique based on acoustic emission (AE) technology that can be used for global nondestructive evaluation (NDE) of steel structures. This will also be useful for the subsequent local inspection used to further monitor cracking, defective connections, retrofit measures, and so forth. The dispersive nature of Lamb wave propagation in plates makes it possible to perform a linear source location of AE events based on the arrival of different frequency components (Lamb wave modes) of an AE event at a single transducer. Experiments on steel beams and plates in the laboratory explored the theory of wave propagation and digital signal processing needed to pursue this objective. Subsequent field investigation on a real bridge substantiated the applicability of this technique. This new technique could allow AE inspection to locate structural problems better, and with a reduced number of transducers.