Vibration-based inverse graphical technique for thickness estimation of bulk acoustic wave (BAW) resonators: application for corrosion monitoring of sacrificial anodes

Monitoring the corrosion of sacrificial anodes in reinforced concrete structures typically requires either destructive inspection or complex inverse modeling. This work introduces a vibration-based inverse graphical technique that estimates the thicknesses of both uncorroded zinc and corroded zinc-oxide layers directly from two resonance frequencies—the radial expansion mode and the transverse “trampoline” mode—captured through electro-mechanical impedance (EMI) sensing.

Unlike optimization-based approaches, the proposed method is calibration-free and computationally light, relying on graphical intersections of analytical frequency relations. Its accuracy is validated using finite element simulations and then demonstrated experimentally through accelerated corrosion tests on zinc anodes in saline environments. The results show that the method can reliably track evolving thicknesses of corroded and uncorroded regions, even under nonlinear delamination dynamics.

By combining simplicity, real-time applicability, and robustness, this technique opens a path for non-destructive, quantitative assessment of sacrificial anodes in smart cathodic protection systems.

Key Findings

• A graphical inverse method estimates zinc and zinc-oxide layer thicknesses from two resonance frequencies.
• The approach is calibration-free and avoids iterative optimization.
• Finite element simulations and accelerated corrosion tests validate the method with good accuracy.
• Provides a computationally inexpensive technique for real-time sacrificial anode health monitoring.

Recommended citation: Thalapil J, Tamhane D, Banerjee S, Tallur S. Vibration-based inverse graphical technique for thickness estimation of bulk acoustic wave (BAW) resonators: application for corrosion monitoring of sacrificial anodes. Smart Mater. Struct. 30 (2021) 055015.
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