An experimental technique for evaluating viscoelastic damping using ultrasonic guided waves.

Area of Science:

• Materials Science
• Acoustics
• Non-destructive Testing

Background:

• Viscoelastic coatings are crucial for damping vibrations.
• Accurate characterization of coating damping is essential for performance optimization.
• Existing methods for determining damping properties can be complex and time-consuming.

Purpose of the Study:

• To develop a simple, low-cost, and time-effective experiment-based fitting method for determining the damping property of viscoelastic coating layers.
• To validate the experimental method using finite element analysis (FEA).
• To assess the technique's precision and reliability for coated waveguides.

Main Methods:

• Utilized symmetric and asymmetric ultrasonic Lamb waves generated by piezo discs on coated and bare plates.
• Determined damping property by comparing the amplitude ratio (AR) of transmitting signals between coated and bare plates.
• Employed ABAQUS finite element method (FEM) software for numerical simulations and validation, using non-dispersive Rayleigh damping (β).

Main Results:

• The experimental method successfully determined the damping property of viscoelastic coatings.
• FEM simulations using ABAQUS corroborated the experimental amplitude ratio (AR) findings.
• Numerical dispersion curves for group velocity validated experimental results with high reliability (average error <1% to 10%).
• Computational cost was reduced by one-tenth by selecting non-dispersive Rayleigh damping.

Conclusions:

• The proposed technique offers a precise and efficient approach for estimating viscoelastic coating damping in waveguides.
• The method's accuracy is influenced by factors including mode selection, frequency range, PZT quality, and waveguide thickness.
• This experiment-based fitting method provides a valuable tool for materials characterization and NDT.