Eliminating undesired high order harmonics in guided ultrasonic waves using local anti-resonance.

A method utilizing the previously unexplored local anti-resonance phenomenon in a Flat Bottom Hole (FBH) is developed to eliminate the interference nonlinearity from undesired sources and enable the precise measurement of ultrasonic nonlinearity from material defects. The local anti-resonance phenomenon in an FBH is investigated using finite element method, on which basis the method to suppress the high order harmonics in incident waves is developed. The effectiveness of the method is validated through the experimental detection of a nonlinear scatterer and comparison with results from traditional configurations. The proposed method demonstrates the capability to precisely and reliably measure defect-specific ultrasonic nonlinearity, thereby advancing the application of the material characterization methods utilizing ultrasonic nonlinearity.