Ultrasonic modeling for multi-layered fluid-solid coupling structures considering defective interfaces: An efficient semi-analytical spectral element method

Abstract

Ultrasonic guided waves play a crucial role in the long-distance inspection of the fluid-solid coupling structures with defective interfaces. However, it is a challenge to calculate dispersion curves for a large number of wave modes due to the complexity of the waveguide structure. In this study, we propose an efficient semi-analytical spectral element method considering a variant-stiffness linear-slip condition to model fluid-solid coupling systems with damaged interfaces. The computational accuracy and efficiency of the proposed method are validated by comparing it with the reference solutions across various numerical scenarios, including immersed solid layers, immersed solid layers with multiple defective interfaces, and fluid-solid coupling structures with thin leaky fluid layers. Additionally, we investigate how the defects influence the dispersion characteristics of trapped or leaky wave modes, illustrating that the advantage of the high-order wave for the long-distance detection of damaged zones. The proposed method can serve as an efficient and robust numerical tool for modeling and characterizing ultrasonic non-detective testing of the damaged fluid-solid coupling structures.