An omnidirectional shear-horizontal guided wave EMAT for a metallic plate

Area of Science:

• Materials Science
• Ultrasonics
• Electromagnetism

Background:

• Guided waves are crucial for non-destructive testing of materials.
• Existing electromagnetic acoustic transducers (EMATs) often lack omnidirectional capabilities for shear-horizontal (SH) waves.
• Efficient generation and detection of omnidirectional SH waves are needed for comprehensive material characterization.

Purpose of the Study:

• To propose and validate a new electromagnetic acoustic transducer (EMAT) design for omnidirectional shear-horizontal (SH) guided wave transduction.
• To achieve uniform SH wave generation and measurement in metallic plates.
• To optimize the EMAT configuration for maximum output.

Main Methods:

• Design of a novel magnetic circuit configuration using ring-type permanent magnets and a specially wound coil.
• Utilizing Lorentz force generated by the interaction of static magnetic flux and induced eddy currents.
• Employing numerical simulations to determine optimal EMAT configurations.
• Experimental validation of the simulated designs and omnidirectional wave generation.

Main Results:

• The proposed EMAT design successfully generates and measures omnidirectional SH guided waves.
• Numerical simulations and experimental results confirm the transducer's omnidirectivity.
• Optimal EMAT configurations were identified to maximize transducer output at specific frequencies.

Conclusions:

• The developed EMAT provides a robust solution for omnidirectional SH guided wave applications.
• This technology enhances the capability for inspecting metallic plates for defects.
• The findings pave the way for advanced non-destructive evaluation techniques using guided waves.