Circumferential SH Wave Piezoelectric Transducer System for Monitoring Corrosion-Like Defect in Large-Diameter Pipes

Current methods for detecting corrosion defects in large-diameter pipes remain limited in accuracy and practicality. While circumferential shear horizontal (CSH) waves offer potential for non-dispersive monitoring, prior research has not fully validated their ability to detect and size corrosion-like defects. Traditional transducers lack the precision to excite pure CSH modes, and no system has yet demonstrated the feasibility of using these waves for defect sizing. This gap motivated the development of a new transducer system that could both excite and detect CSH waves in pipes. Prior work has shown that Lamb waves are commonly used for defect detection, but they suffer from dispersion, which complicates interpretation. The need for a reliable, non-dispersive alternative led to a focus on CSH waves. However, no prior work had resolved how to effectively excite and measure these waves in practical pipe geometries. This uncertainty drove the current investigation into transducer design and defect sizing capabilities. The absence of experimental validation for CSH wave sizing in corrosion defects remains a critical issue in structural health monitoring.

This study aimed to evaluate the feasibility of using circumferential shear horizontal (CSH) waves for monitoring corrosion-like defects in large-diameter pipes. The primary objective was to develop a transducer system capable of exciting and detecting pure CSH modes. A secondary goal was to test whether these waves could accurately size defects, such as notches, in steel pipes. The researchers also sought to investigate how defect depth affects wave transmission and reflection characteristics. By addressing these questions, the study aimed to advance structural health monitoring (SHM) techniques for pipe systems. The motivation stemmed from the limitations of existing methods, which often fail to provide reliable defect sizing. The team focused on CSH waves due to their non-dispersive nature, which simplifies interpretation. The study also aimed to bridge the gap between theoretical wave propagation and practical SHM applications.

The researchers first analyzed the mechanism for exciting circumferential shear horizontal (CSH) waves in steel pipes. They proposed a method using bidirectional SH wave piezoelectric transducers to generate pure CSH₀ and CSH₁ modes. Finite element simulations were conducted to model wave propagation in 1-mm thick steel pipes. Experiments validated the simulations by measuring wave behavior at frequencies between 100 and 300 kHz. The transducer was also tested as a sensor to detect CSH₀ waves while filtering out Lamb waves. A defect sizing method was developed using CSH₀ waves to measure notch depth and circumferential extent. Experiments on 11-mm thick steel pipes confirmed the method’s accuracy. Finally, the team tested how CSH₀ and CSH₁ waves interacted with notches of varying depths.

Experiments confirmed that the bidirectional transducer could excite pure CSH₀ waves in 1-mm thick steel pipes at frequencies from 100 to 300 kHz. The transducer also functioned as a sensor, detecting CSH₀ waves while filtering out Lamb waves up to 450 kHz. The defect sizing method successfully determined notch depth and circumferential extent in 11-mm thick pipes. Transmission coefficients of CSH₀ waves decreased as notch depth increased, indicating their potential for monitoring corrosion progression. Simulations and experiments showed strong agreement in wave behavior. The system demonstrated high accuracy in defect sizing with minimal dispersion effects. These findings suggest that CSH waves can be used for reliable corrosion monitoring in large-diameter pipes. The results support the feasibility of using CSH₀ waves for structural health monitoring applications.

The study demonstrated that the proposed transducer system can effectively excite and detect pure CSH₀ waves in steel pipes. The system’s ability to filter out Lamb waves over a wide frequency range enhances its practicality for structural health monitoring (SHM). The defect sizing method showed that CSH₀ waves can accurately determine notch depth and circumferential extent. The observed decrease in transmission coefficients with increasing notch depth supports the use of these waves for monitoring corrosion progression. The findings suggest that CSH₀ waves are suitable for non-dispersive defect monitoring in large-diameter pipes. The transducer system’s performance in both simulation and experiment validates its potential for real-world applications. The results align with the authors’ hypothesis that CSH waves can provide reliable corrosion monitoring. These conclusions highlight the importance of developing specialized transducers for SHM systems.