Imaging of three-dimensional crack open/closed distribution by nonlinear ultrasonic phased array based on fundamental wave amplitude difference
Yoshikazu Ohara, H. Nakajima, Sylvain Haupert, Toshihiro Tsuji, Tsuyoshi Mihara
Abstract
Abstract We investigated the imaging capability of fixed-voltage fundamental wave amplitude difference (fixed-voltage FAD), which is one of the nonlinear ultrasonic phased array imaging techniques, for three-dimensional crack open/closed distribution. We fabricated two fatigue crack specimens with different thicknesses, which were selected to create different open/closed distributions in them. As a result of applying fixed-voltage FAD with mechanical scans to the thick and thin specimens, the difference in the crack open/closed distribution was successfully visualized. The results are in good agreement with fracture mechanics. Thus, it was demonstrated that fixed-voltage FAD is useful not only for nondestructive testing for aging infrastructures but also for the progress in fracture mechanics.