Generation of long-range, near-cut-on guided resonances in composite panels

In this paper, near-cut-on guided resonances (GRs) are generated in a composite structure using an array of piezoelectric transducers. A GR is a type of high-order unidirectional wave mode, guided between the finite boundaries of a periodic waveguide's cross section. Near their cut-on frequency, these waves often exhibit high chromatic dispersion and spatial decay, which compromise their potential use for wave-based inspection and structural health monitoring of advanced composites or metamaterials. A custom GR actuator is designed to achieve an accurate shape appropriation of the predicted 3D Floquet-Bloch solutions in a 3-m-long sandwich structure. An original wave conversion phenomenon is then exploited to generate almost nondispersive selected GR pulses near their cut-on frequency. Full wavefield measurements are conducted in time domain using a laser Doppler velocimeter to provide new insights into the GR near-cut-on scattering effects in the low vibroacoustic bandwidth. (c) 2019 Author(s).