High-frequency dynamic acoustic field manipulation method and its application to flaw evaluation and imaging.

Existing approaches for acoustic field manipulation using acoustic lenses mainly focuses more on low-frequency, particularly audible range, and static fields with limited applicability to ultrasonic regimes. This paper proposes a megahertz-range rotational acoustic field manipulation method based on an acoustic lens and investigates its application in flaw evaluation and imaging. Theoretical analysis of dynamic acoustic field propagation was conducted at frequencies up to the megahertz range, leading to the formulation of a motion-modulated transmission model to describe field regulation. Additionally, a composite flaw evaluation method was introduced based on directional rotation of the dynamic field. Simulation and experimental results demonstrate that this method offers superior performance in directly identifying the orientation and size of flaws with a maximum angle error of only 0.3%. Compared to traditional ultrasonic imaging, this method provides 15% and 18% improvements in accuracy of angle and size, respectively, and presents an efficient guide for dynamic ultrasonic field manipulation and directional field application.