Identification of dual notches based on time-reversal lamb waves and a damage diagnostic imaging algorithm

Abstract

An integration of time-reversal Lamb wave signals from a sensor network and a damage diagnostic imaging algorithm is developed to identify dual notches in an aluminum plate. The time reversibility of Lamb waves for one wave propagation path in an aluminum plate is investigated using dynamic finite element analysis (FEA). A time-reversal-based damage index (DI) is calibrated by correlation of the reconstructed waveform and the original activated tone burst, when the fundamental symmetric (S₀) mode alone is reversed or when both the S₀ mode and the fundamental antisymmetric (A₀) mode are reversed. Simulation results demonstrate that the calibrated DI is almost identical for the time reversal of single or multiple Lamb modes. On the basis of the time reversibility of Lamb waves, dual notches in an aluminum plate are identified using the damage diagnostic imaging algorithm in the experiment. With the availability of time-reversal-based DI for individual sensing paths on the aluminum plate, the probability values for the presence of dual notches are estimated in the inspected area enclosed by the sensor network. Identification results demonstrate that the integrated approach with time-reversal Lamb waves and the damage diagnostic imaging algorithm is independent of additional benchmark signals, and it can be used confidently to locate multiple instances of damage.