Remote characterization of defects in plates with viscoelastic coatings using guided waves

Area of Science:

• Non-destructive testing
• Ultrasonic testing
• Materials science

Background:

• Guided waves are effective for remote inspection of metallic structures like pipes and plates.
• Surface coatings, often viscoelastic, can attenuate guided waves, reducing inspection range.
• Previous research identified low-attenuated modes for defect detection and location.

Purpose of the Study:

• To investigate the use of guided waves for both locating and sizing defects in plates with viscoelastic coatings.
• To analyze mode conversion at defects under coatings to improve defect characterization.
• To identify trends and features for defect sizing using guided wave analysis.

Main Methods:

• Utilizing a hybrid finite element-boundary element method.
• Explicitly incorporating the attenuating characteristics of viscoelastic coatings.
• Calculating Lamb and SH mode conversion factors at defects.

Main Results:

• Numerical simulations were performed to analyze mode conversion at defects.
• Parametric studies were conducted to understand the influence of coating properties and defect characteristics.
• Trends and features relevant to defect sizing were identified from the results.

Conclusions:

• Guided wave inspection can be optimized for coated structures by selecting appropriate modes and frequencies.
• The hybrid modeling approach accurately captures the effects of viscoelastic coatings on guided wave propagation.
• The identified trends provide a basis for developing guided wave techniques for defect sizing in coated plates.