Detection and localization of fatigue crack using nonlinear ultrasonic three-wave mixing technique

Abstract

Herein, we developed a nonlinear ultrasonic three-wave mixing technique to more accurately detect and localize early-stage fatigue cracks. First, we derived the theoretical relationship between third-order combined harmonics (TOCH) and fatigue crack size based on Paris–Erdogan and Nazarov–Sutin theories, and developed a detailed analytical model to calculate the size of the mixing zone. Next, we experimented with aluminum specimens to validate the effectiveness of the proposed technique. Furthermore, the amplitude variation of TOCH with respect to fatigue crack cycles was investigated. Comparative results confirmed that the proposed technique shows higher sensitivity toward fatigue cracks than conventional nonlinear ultrasonic techniques.