Compact Functional Material Wedge for Oblique Angle Ultrasound

Achieving improved composites lifecycle management requires more sophisticated damage evolution models and advances in nondestructive evaluation of the damage state. Recent efforts in characterizing impact damage using an acoustic wedge-assisted pitch-catch phased array technique have revealed challenges with lateral beam steering, signal-to-noise, and signals analysis in conjunction with complicating internal reflections from the acoustic wedge. One solution being considered is the application of an additively-manufactured compact acoustic wedge that uses graded material properties to promote lateral beam steering using elements with a normal orientation, with minimal internal reflections. A simplified proof-of-concept of this approach was demonstrated via simulation of ultrasonic waves propagating through a functionally-graded wedge into a target body. Results highlighted the importance of the compact wedge boundary conditions to mitigate secondary longitudinal and shear wave signals.