A time–distance domain transform method for Lamb wave dispersion compensation considering signal waveform correction

Abstract

In Lamb wave identification, time–distance domain mapping (TDDM) is one of the most popular methods for dispersion compensation. However, it is found that the processed signal waveforms are easily deformed by TDDM. To improve the compensation effect, a time–distance domain transform (TDDT) method is presented in this paper. In TDDT, both dispersion removal and signal waveform correction are accomplished to result in more convenience of dispersive signal interpretation. Instead of the complex back-propagation concept, only the basic Fourier transform (FT) properties are used to study the principle of TDDT. The realization of TDDT under broadband excitation and narrowband excitation is discussed, in which the signal waveform maintenance is of particular interest and the reason for TDDM disturbance of the signal waveforms is also investigated. Numerical simulations on A0 or S0 mode signals are implemented for the primary validation of TDDT. Then, in association with the traditional delay-and-sum algorithm, a high spatial resolution imaging method based on TDDT is developed. An experimental study is finally arranged to demonstrate the efficiency of TDDT and the TDDT-based imaging method.