Localization and sizing of discontinuities using lamb-waves

Copyright 2003 by DEStech Publications, Inc. All right reserved. This active sensing diagnostics methodology consists of an automated procedure capable of detecting and sizing notches and holes in isotropic plates. Piezoelectric transducers are used to generate and detect Lamb waves in perfect plates and plates containing discontinuities. Experimentally measured time-domain signals are first transformed into the time-frequency domain using a short time Fourier transform (STFT) and subsequently into the slowness-frequency domain. Finally, the discontinuity is located with a special correlation in the slowness-frequency domain. The advantage of the slowness-frequency domain representation (over the time-frequency representation) is its invariance with respect to source-receiver distance. Moreover, the slowness-frequency domain representation is a linear transformation as opposed to the group-velocity frequency representation. A verification of the proposed methodology shows excellent agreement with the actual location of the discontinuity. Furthermore, the size of the discontinuity is identified by taking into account the amplitude of the obtained correlation curve.

Structural Health Monitoring 2003: From Diagnostics and Prognostics to Structural Health Management - Proceedings of the 4th International Workshop on Structural Health Monitoring, IWSHM 2003

Localization and sizing of discontinuities using lamb-waves Conference Paper