Generalized Debye series expansion to improve the non-destructive testing and health monitoring of cylindrical structures by guided waves

Abstract

Many structures in civil engineering notably bridges and nuclear power plants must be regularly, strictly, and carefully tested to avoid any human or environmental catastrophe. Among the NDT techniques, which can be applied, ultrasonic guided waves are a good candidate to monitor bars and cables. However, its multimodal and dispersive behaviors can limit its performances. Theoretical modeling is sometimes needed to understand the behavior of the traveling waves to improve the testing/monitoring and made a right in-situ decision. The aim of this paper is to derive the space-time velocity field in a cylindrical waveguide perfectly embedded in an infinite solid matrix and generated by an inside bounded beam. This beam is generated by an off-axis source. Vector Hankel transform and Fourier series are combined to decompose the inside field into infinity of elementary cylindrical waves propagating in radial direction and planar waves propagating in axial direction. Global resolution method and Generalized Debye...