Guided wave structural health monitoring using CLoVER transducers in compositematerials

Abstract

The guided wave (GW) field excited by piezoelectric wafers and piezocomposite transducersin carbon-fiber composite materials is experimentally investigated with applications tostructural health monitoring. This investigation supports the characterization of thecomposite long-range variable-length emitting radar (CLoVER) transducer introduced bythe authors. A systematic approach is followed where composite configurations withdifferent levels of anisotropy are analyzed. In particular, unidirectional, cross-ply[0/90]3S andquasi-isotropic [0/45/–45/90]2S IM7-based composite plates are employed. A combination of laser vibrometry and finiteelement analysis is used to determine the in-plane wave speed and peak-to-peak amplitudedistribution in each substrate considered. The results illustrate the effect of the materialanisotropy on GW propagation through the steering effect where the wavepackets do notgenerally travel along the direction in which they are launched. After characterizing theeffect of substrate anisotropy on the GW field, the performance of the CLoVER transducerto detect damage in various composite configurations is explored. It is found that thedirectionality and geometry of the device is effective in detecting the presenceand identifying the location of simulated defects in different composite layups.