Waveform correlation factor (WCF) weighted TFM imaging for Lamb wave phased array

Aimed at improving the imaging performance of the classical total focusing method (TFM), which is an effective post-processing technique for Lamb wave phased array based damage imaging, a waveform correlation factor (WCF) weighted TFM imaging algorithm is proposed. In the proposed algorithm, besides the signal amplitude used in the classical TFM, the waveform correlation coefficients between any two waveforms after dispersion compensation are also utilized for damage imaging. Waveform correlation coefficients will be large if the wave packets are caused by the same imaging point, or they will be small due to the change in waveform shape arising from dispersion. For each imaging point, dispersion compensation for all collected signals is respectively implemented so that the scattering waveforms can be extracted. Then the waveform correlation coefficients between any two scattering waveforms are calculated and weighted on the corresponding amplitude used in the TFM. By comparing the imaging results of the proposed algorithm with that of the classical TFM algorithm, it is found that the proposed algorithm can significantly reduce the background noise and thus improve the imaging performance. •A new damage imaging algorithm to improve imaging performance of the classical TFM.•Fusion of signal amplitudes and waveform correlation coefficients for imaging.•Remarkable reduction in background noise of imaging results.•Experimental validations using linear and circular arrays.