A Comparative Study of Three Types Shear Mode Piezoelectric Wafers in Shear Horizontal Wave Generation and Reception

Guided wave-based inspection has emerged as a promising tool to evaluate the reliability of key components in modern industries. The fundamental shear horizontal (SH₀) wave is always of great interests for plate-like structures because of its non-dispersion characteristics. However, the generation and reception of SH₀ wave using piezoelectric wafers is not straightforward. In this paper, we firstly define three types shear mode piezoelectric wafers, i.e., the conventional in-plane poled thickness-shear (d₁₅) mode, the thickness-poled thickness-shear (d₁₅) mode, and the face-shear (d₂₄) mode. Then, finite element simulations were conducted to demonstrate their performance in SH wave generation and reception. The results indicated that the face shear d₂₄ wafer can generate almost single mode SH₀ wave, while both types of d₁₅ wafers would generate Lamb waves and SH₀ wave simultaneously. Finally, experiments were carried out to check the efficiency of different shear mode piezoelectric wafers in SH₀ wave generation and reception. The results indicated that the d₂₄ wafer can generate and receive SH₀ wave of high signal to noise ratio (SNR) with high energy conversion efficiency, while the in-plane poled d₁₅ wafer would generate SH₀ wave of high amplitude and acceptable SNR but with relatively low energy conversion efficiency. The performances of thickness-poled d₁₅ wafer was not as good as the other two in both SH wave generation and reception. This work will be helpful for the applications of SH waves in plate-like structures.