Ultrasonic non-destructive testing method based on a flexible microchannel array acoustic metasurface lens

Area of Science:

• Materials Science
• Acoustics
• Non-Destructive Testing

Background:

• Conventional ultrasonic non-destructive testing (NDT) uses rigid acoustic lenses (wedges) that cause energy loss and limit testing on uneven surfaces.
• The fixed geometry of traditional lenses hinders conformal coupling and efficient ultrasonic wave transmission.

Purpose of the Study:

• To develop a novel phase-gradient acoustic metasurface using a flexible microchannel array for ultrasonic NDT.
• To enable ultrasonic field modulation and conformal coupling to irregular surfaces for enhanced testing capabilities.

Main Methods:

• Designed and investigated a flexible microchannel-based acoustic metasurface for MHz ultrasonic applications.
• Evaluated beam redirection, wavefront control, and mechanical deformation robustness of the metasurface.
• Conducted experimental validation of the metasurface in ultrasonic NDT scenarios.

Main Results:

• The metasurface lens increased deflected signal amplitude by over 40% compared to conventional wedge lenses.
• Eliminated the need for water immersion, simplifying the NDT process.
• Successfully conformed to inclined surfaces (±15°) and detected subsurface defects with 0.25 mm crack resolution.

Conclusions:

• The proposed flexible acoustic metasurface offers a new paradigm for ultrasonic NDT, overcoming limitations of rigid lenses.
• This technology enables dynamic wavefront control and conformal coupling for intelligent NDT systems in complex environments.
• Provides theoretical and experimental foundations for advanced NDT applications.