Flexural-guided-wave mode F(1,1) based inspections for small-bore tubes with bends

Area of Science:

• Mechanical Engineering
• Materials Science
• Non-Destructive Testing

Background:

• Small-bore tubes are critical industrial components but difficult to inspect due to size and accessibility.
• Existing inspection methods struggle with the complex geometries of bent tubes.

Purpose of the Study:

• To investigate the use of the flexural guided-wave mode F(1,1) for inspecting small-bore tubes with bends.
• To develop and validate a novel magnetostrictive patch transducer for F(1,1) excitation.

Main Methods:

• Proposed a magnetostrictive patch transducer for F(1,1) mode excitation.
• Conducted magnetic field simulations to optimize transducer performance.
• Numerically analyzed F(1,1) mode scattering through tube bends.
• Performed experimental validation of excitation, scattering, and defect detection.

Main Results:

• The F(1,1) mode exhibits unique focusing properties and scattering behavior at bends.
• Optimized transducer design achieved uniform magnetic fields for pure F(1,1) excitation.
• Scattering analysis revealed mode conversions (T(0,1) and L(0,1)) dependent on focusing position.
• Successfully detected defects with 6% cross-sectional area loss without masking by bend signals.

Conclusions:

• The F(1,1) guided-wave mode is a viable tool for inspecting bent small-bore tubes.
• The developed transducer enables effective F(1,1) excitation and analysis.
• The study provides insights into F(1,1) mode scattering at bends, enhancing defect localization capabilities.