Research on detection sensitivity based on wave structure of Lamb wave

Dispersion and multi-mode occurred when Lamb wave propagate in the lamina, the reflection principle of Lamb wave is complicated while it encounter defects. For diverse defects, different modes have different sensitivities. The theoretical of displacement and stress wave structure are analyzed. The dispersion curve and wave structure curve are presented. Piezoelectric (PZT) ceramic wafers are applied for excitation and reception of guided wave in the experiment and different frequencies under low FD (the product of frequency and thickness) are optimized for evaluate the defects. The sensitivity for diverse defects is derived according to the change of amplitude. Experimental results show that there are a good corresponding relationship between the wave structure and the detection sensitivity.