Scattering characteristics of quasi-Scholte waves at blind holes in metallic plates with one side exposed to water

Abstract

Corrosion is one of the major issues in metallic structures, especially those operating in humid environments and submerged in water. It is important to detect corrosion at its early stage to prevent further deterioration and catastrophic failures of the structures. Guided wave-based damage detection technique is one of the promising techniques for detecting and characterizing damage in structures. In water-immersed plate structures, most of the guided wave modes have strong attenuation due to energy leakage into the surrounding liquid. However, there is an interface wave mode known as quasi-Scholte waves, which can propagate with low attenuation. Therefore, this mode is promising for structural health monitoring (SHM) applications. This paper presents an analysis of the capability of quasi-Scholte waves in detecting internal corrosion-like defects in water-immersed structures. A three-dimensional (3D) finite element (FE) model is developed to simulate quasi-Scholte wave propagation and wave scattering phenomena on a steel plate with one side exposed to water. The accuracy of the model is validated through experimental measurements. There is good agreement between the FE simulations and experimental measurements. The experimentally verified 3D FE model is then employed in a series of parametric studies to analyze the scattering characteristics of quasi-Scholte waves at circular blind holes with different diameters and depths, which are the simplest representation of progressive corrosion. The findings of this study can enhance the understanding of quasi-Scholte waves scattering at corrosion damage of structures submerged in water and help improve the performance of in-situ damage detection techniques.