High frequency guided waves in a 7 wire strand: Warped Frequency Transform for spectro-temporal characterization

The aim of this research is to characterize the guided waves behavior in a seven wire strand with particular interest to the dispersive waves attenuation. Here, a pilot study is carried out on a carbon-fiber-reinforced-polymer (CFRP) wire to test a new signal processing procedure aimed at the extraction of the dispersive waves attenuation. The approach uses a novel time-frequency transform (TFR) capable to isolate the dispersive behavior of a single mode from a multimodal and dispersive recorded time-waveform. This TFR, called ¿Warped Frequency Transform¿ (WFT), is based on a time-frequency domain tiling chosen to match the spectro-temporal structure of the different propagating guided waves. The WFT is used to highlight the energy content of a guided wave traveling along the wire at different locations from which its dispersive attenuation information can be extracted. Here, the longitudinal L(0,1) wave in a single CFRP wire is studied.