The Characteristic of Wedge Waves Propagating along Wedge with Periodic V-defects by Laser Ultrasound Technique

The investigation focuses on analyzed the influence of periodic V-defects on wedge waves by laser ultrasound technique. Usually, wedge tip is almost non-perfect, which may bring in break and enormous economic losses. The wedge waveguide models with different periodic V-defects were established by using finite element method. We have observed multiple mode wedge waves in 20 degrees wedge. The depth of defect is 0.1mm, and the periodic number are 1, 6, 12, and 24, respectively. Both reflected and transmitted waves are observed. And the low order reflected wave and transmitted wave modes separate from high order mode. As periodic number increase, the amplitude of reflected wave and transmitted wave decreased. By integrating the power spectra of the wedge waves, the energy distribution of these wedge waves of different periodic are analyzed. It is found that the energy has a fluctuation, which could be determined the location of defect. The energy has a gradually increase as the propagation before defect, and dramatic decrease after the defect. The results of this study can provide theoretical guidance for the positioning and size estimation of wedge defects.