Damage detection in plate structures based on baseline construction of ultrasonic Lamb wave using designed mobile transducer set

The ultrasonic Lamb wave-based damage detection method is widely used in plate structures. Due to the multimode characteristic, the collected Lamb wave signals are very complicated, making it difficult to obtain damage information. This paper proposes a damage imaging algorithm based on the baseline construction of the Lamb wave for plate structures. A mobile transducer set including two transducers is designed for Lamb wave excitation and signal collection. To extract damage scattering signals, the response of the signal in healthy areas (the structural response signal) is measured as a temporarily constructed baseline signal. The structural response signal is obtained based on the identified healthy signals collected in different areas of the same structure. Damage scattering signals are extracted as the differences between the current signals and the structural response signal. Damage indexes are calculated based on the damage scattering signals to locate the damage with the imaging algorithm. A damage detection experiment is conducted on an aluminum plate to verify this proposed method. The imaging result is in good agreement with the damage location in the experiment. This paper provides a potential alternative for damage detection of plate structures in practice.