Ultrasonic structural health monitoring: an overview

Piezoelectric transducers have a long history of applications in nondestructive evaluation (NDE) of material and structure integrity owing to their ability of transforming mechanical energy to electrical energy and vice versa. From an acoustic point of view, there is no difference between structural health monitoring (SHM) and conventional NDE since both rely on the same physics in the sense that in either case acoustic wave need to be generated and then detected. This paper presents and discusses an overview of ultrasonic SHM techniques. After a brief introduction, it presents the PWAS-based SHM principle, which is followed by a discussion of the passive and active ultrasonic SHM techniques. The paper identifies advantages and disadvantages of these nondestructive methods and guidelines for future work.