Ultrasonic imaging of spherical solids embedded in ice

Area of Science:

• Materials Science
• Nondestructive Testing
• Acoustics

Background:

• Ultrasonic wave transmission into rigid solids with doubly-curved surfaces is limited in liquid media, hindering cross-sectional imaging.
• Achieving normal incidence for ultrasonic beams is difficult with linear transducer arrays, restricting imaging capabilities.

Purpose of the Study:

• To investigate the feasibility of imaging the interior of solids with complex geometries using frozen water as a medium.
• To analyze the impact of frozen water on ultrasonic wave propagation and image fidelity.
• To develop a framework for correlating ultrasonic images with the internal structure of solids.

Main Methods:

• Utilizing frozen polycrystalline ice as a coupling medium for ultrasonic compressional waves.
• Analyzing the deflection of ultrasonic rays within the solid due to surface curvature.
• Developing a ray-based framework to model wave propagation and image formation.

Main Results:

• Freezing the liquid medium significantly enhances ultrasonic wave transmission over a broader range of incidence angles.
• Two-dimensional images may not perfectly represent the 3D structure due to ray deflection, but approximate a parallel section.
• The ray-based framework accurately correlates images to the solid's structure, applicable to complex surfaces.

Conclusions:

• Imaging dense solids with complex geometries is enhanced by using frozen water, overcoming limitations of liquid coupling.
• The developed ray-based model provides a method to interpret ultrasonic images of complex structures in nondestructive testing.
• This approach offers improved fidelity for inspecting metallic components with challenging geometries.