Study of circumferential waves and their interaction with defects on cylindrical shells using line-source laser ultrasonics

An application of laser ultrasonics to investigate circumferential waves and their interaction with defects on cylindrical structures is presented. Due to the high effectiveness of the laser line-source generation regime and the broadband nature of the system, circumferential waves could be generated and detected with a wide bandwidth and an excellent signal-to-noise ratio. A clear recognition of multimode wave forms is achieved by two-dimensional Fourier transform signal processing. Measurements were also made on a cylindrical shell with a crack-like defect which was simulated by an artificial groove on the surface of the specimen. The interaction of the circumferential waves with a defect in the inner or outer surface of the thin cylindrical shell has been studied. The results may lead to an application for defect identification at the inner or outer surface of thin cylindrical shells. (C) 2002 American Institute of Physics.