A dual-mode piezoelectric transducer for selective excitation and reception of bidirectional S₀ and SH₀ waves

Abstract Transducers play a crucial role in guided wave-based structural health monitoring (SHM). Most transducers are designed to excite a single wave mode to reduce signal complexity from multimodal characteristics. However, different wave modes detect different defects, necessitating multiple transducer types for comprehensive defect identification. This conflicts with the goal of minimizing sensor numbers for large-area monitoring. In this work, a dual-mode piezoelectric transducer (DMPT) is introduced for the selective excitation and reception of bidirectional S 0 (fundamental symmetric Lamb wave) and SH 0 (fundamental shear horizontal wave) waves. The DMPT consists of two identical piezoelectric ceramic wafers placed side by side with two pairs of electrodes. By selecting different electrode pairs as active, the operational mode can be easily changed. Finite element simulations and experimental tests show that in S 0 mode, the DMPT generates bidirectional S 0 waves within 300 ∼ 400 kHz along the working direction. In SH 0 mode, it produces bidirectional SH 0 waves across 125 ∼ 175 kHz in the same direction. Additionally, the DMPT selectively detects and identifies S 0 and SH 0 waves in the working direction while attenuating them in the non-working direction. The proposed DMPT offers a cost-effective solution for selective excitation and reception of bidirectional S 0 and SH 0 waves using a single transducer, potentially reducing the number of transducers needed in sensor networks, which is significant for SHM applications.