Application of Laser-Generated Ultrasonic to Phase Transformation Analysis in Shape Memory Alloy Sheets

摘要

Lamb wave dispersion curves for NiTi shape memory alloy sheet are given. The multimode Lamb waves were generated in NiTi sheet by a pulse laser beam. The modes sensitive in characterizing phase transformation were selected on the basis of the dispersion curves. Piezoelectricity transducers were used to receive S_1 and S_3 Lamb wave, the group velocities of which were measured at different temperatures. The results show that a marked variation in group velocity is observed during phase transformation, and the dependence of group velocity versus temperature provides a new and effective means of inspecting NiTi alloy phase transformation.