A phased array ultrasonic-based enhanced strategy of critically refracted longitudinal (LCR) wave technique.

Conventional critically refracted longitudinal (L CR) wave technique seriously relies on the first critical angle (θ C R ), showing poor adaptability to the wave velocity variations of materials in defect and stress characterization. We propose an enhanced strategy based on the phased array ultrasonic, termed PA-L CR. Three typical beam profiles, deflection, focusing and their combination, are studied on the excitation of L CR wave. With one fixed wedge and time delay law, the wave can be excited within a wild angle range relative to θ C R , about ± 7 ° for −6 dB amplitude, and the adaptable longitudinal wave velocity is ranged about 6000 m/s. In addition, a calculation method of the L CR wave velocity is also proposed and verified. • A phased array ultrasonic-based enhanced strategy, PA-L CR , is proposed for L CR wave. • With one wedge and time delay law, L CR wave can be excited in different materials. • The adaptable first critical angle and P wave velocity range about 20 ° and 6000 m/s. • A new method to calculate the L CR wave velocity is proposed and verified. • PA-L CR strengthens the convenience and performance of L CR characterization. [ABSTRACT FROM AUTHOR]