Context: Recently, Researchers in the Indian Institute of Technology Madras and the University of Nairobi have used metamaterials to improve detection of defects in large structures by guided wave ultrasound.
Key Points

• Engineering structures including buildings, pipelines and rails require periodic testing to prevent catastrophic failures occurring due to corrosion, impact, and strain.
• High-frequency sound waves that travel in the bulk are widely used for non-invasive and non-destructive testing of structural materials.
• Conventional bulk ultrasonic inspection is tedious and time-consuming as it involves point-by-point assessment of structures.

About Guided Wave Testing

• In guided wave testing (GWT), the sound waves are sent along the length of the structure rather than into the structure, allowing the waves to travel longer distances.
• GWT has poorer resolution than conventional ultrasound-based testing due to diffraction limitations.
• The research team used metamaterials to improve the resolution of guided ultrasound waves.

About Meta Materials

• Metamaterials are artificially crafted materials with unique internal microstructures that give them properties not found in nature.
• The constituent artificial units of the metamaterial can be tailored in shape, size, and interatomic interaction, to exhibit unusual properties.
• Unique character: For electromagnetic waves with relatively large wavelengths, the composite structure acts as an array of artificial atoms, giving rise to unique and exotic electromagnetic properties.