Abstract
In this paper, to investigate the state of stress around the v-notch tip in the epitaxial gallium nitride (GaN) substrate under the incidence of the ultrasonic wave, several photoelastic strips with different sizes of v-notches were prepared. The resulting photoelastic fringe patterns were obtained by the time-averaged photoelastic technique. In addition, commercially available finite element method (FEM) software package ANSYS was employed to verify the experimental results. Very well-matched results between the photoelastic and FEM were obtained. The von Mises stress distribution ahead of the notch tip was also calculated by ANSYS to evaluate the appropriateness of the dimensions of the v-notch.