A Single-Channel Multifrequency Simultaneous Excitation System Using Bandpass Filter Circuit Modules for Lamb Wave-Based Damage Imaging

Structural health monitoring (SHM) systems often employ Lamb wave transducer arrays for damage detection and localization. The simultaneous excitation of multiple transmitters offers an efficient data acquisition strategy. This article presents a single-channel, multifrequency simultaneous excitation system for Lamb wave-based damage imaging. First, a low-cost bandpass filter circuit module is used to divide the excitation signal into distinct frequency ranges under the single signal generator. Subsequently, the excitation signal is optimized to constrain the actual excitation applied to the transmitter to specific frequency ranges, ensuring nearly orthogonal distribution between the excitation signals of different transmitters. On this basis, the response signals are separated in the frequency domain and matched to their respective transmitters for damage localization. The effectiveness of the proposed method is validated through experiments conducted on an aluminum plate with a hole and simulated damages.