A single-phase elastic hyperbolic metamaterial with anisotropic mass density.

Area of Science:

• Materials Science
• Acoustics
• Nanotechnology

Background:

• Locally resonant metamaterials offer unique properties for manipulating wave propagation at subwavelength scales.
• Anomalous anisotropy in metamaterials is key for developing hyperlenses and achieving superior-resolution imaging.

Purpose of the Study:

• To design a single-phase elastic metamaterial with strongly anisotropic effective mass density.
• To demonstrate the potential of this metamaterial for subwavelength imaging applications.

Main Methods:

• Design of a single-phase elastic metamaterial utilizing independently adjustable local resonant motions.
• Application of numerical-based effective medium theory to achieve high anisotropy in effective mass densities.
• Integration of shunted piezoelectric elements to tailor effective mass density across a broad frequency range.

Main Results:

• Achieved high anisotropy in effective mass densities, including opposite signs, through microstructure design.
• Numerically validated an elastic hyperlens constructed from the designed hyperbolic metamaterial.
• Demonstrated subwavelength longitudinal wave imaging using the elastic hyperlens.

Conclusions:

• The proposed single-phase hyperbolic metamaterial exhibits promising properties for advanced wave manipulation.
• This metamaterial holds significant potential for high-resolution damage imaging in nondestructive evaluation and structural health monitoring.