High-resolution thickness maps of corrosion using SH1 guided wave tomography

Area of Science:

• Materials Science
• Non-Destructive Testing
• Ultrasonic Wave Propagation

Background:

• Quantifying corrosion in the petrochemical industry is critical for safety and maintenance.
• Guided wave tomography offers thickness mapping but suffers from limited in-plane resolution (typically ~4T).
• Existing methods struggle to image small defects, defined as 3 times the wall thickness (3T).

Purpose of the Study:

• To investigate the suitability of the first-order shear-horizontal (SH1) guided wave mode for improved resolution in guided wave tomography.
• To overcome the resolution limitations of fundamental modes (A0 and S0) for defect detection.

Main Methods:

• Utilized finite-element simulations to model guided wave propagation and scattering.
• Employed experimental validation to confirm simulation findings.
• Focused on the SH1 guided wave mode due to its shorter wavelength (~1T).

Main Results:

• The SH1 mode demonstrated a significantly shorter wavelength, enabling approximately 2.4 times better in-plane resolution.
• Finite-element simulations and experimental results confirmed the improved resolution.
• Successfully achieved reliable detection and sizing of defects up to 3T-by-3T.

Conclusions:

• The SH1 guided wave mode is highly effective for enhancing the resolution of guided wave tomography.
• This advancement allows for the reliable detection and sizing of critical 3T-by-3T defects.
• The study achieves a long-sought goal in guided wave tomography for industrial inspection.