Experiments on coupled axial–flexural wave propagation in a sagged rod with structural discontinuity using piezoelectric transducers

A damage evaluation methodology in a sagged prismatic rod through application of wave propagation mechanics is presented, and an experimental investigation an experimental investigation is illustrated for damage detection using lead zirconate titanate (PZT) piezoelectric transducers. Discontinuity in the form of variation of the cross-sectional area (impedance mismatch) is induced in the longitudinal direction of the experimental specimen by butt welding two steel rods, as described in the previous work. The proposed methodology outlined for a sagged prismatic rod can be adopted for damage detection in a transmission line conductor made of wire rope. The corresponding wave reflections from the damage and boundaries are highlighted. Experiments are conducted on a predominantly single frequency based amplitude modulated narrow-banded, burst wave propagation. The novelty of the work is the experimental demonstration of narrow-banded single frequency wave generation with PZT patches with facility for a variable frequency excitation and controlled by a function generator. This is different from the conventional resonating piezo-crystal at ultrasonic frequency range, where the excitation is strong but the frequency is not variable. Also, the methodology is proposed for bifurcating the initial portion of the nondispersive wave propagation from a mixed-up response. For locating the bifurcation zone for axial–flexural wave interaction, a moving correlation coefficient method is employed. Thus, the use of PZT transducers for online monitoring of damage identification in sagged rod is promising for the future work.