Modelling of waves propagation on irregular surfaces using ray tracing and GTD approaches: Application to head waves simulation in TOFD inspections for NDT

12th Anglo-French Physical Acoustics Conference

Ferrand, Adrien^1 ; Darmon, Michel^1 ; Chatillon, Sylvain^1 ; Deschamps, Marc^2

CEA, LIST, Department Imaging and Simulation for NDT, 91191 Gif-sur-Yvette cedex, France^1

University Bordeaux, I2M-APy, UMR 5295, 33400 Talence, France^2

关键词: Geometrical theory of diffraction;    Non destructive evaluation;    Precise positioning;    Propagation modeling;    Ray-tracing technique;    Surface irregularities;    Time-of-flight diffraction technique;    Ultrasonic methods;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/498/1/012011/pdf
DOI  :  10.1088/1742-6596/498/1/012011

来源: IOP

【 摘 要 】

The Time of Flight Diffraction (TOFD) technique is a classical ultrasonic method used in ultrasonic non-destructive evaluation, which allows a precise positioning and a quantitative size evaluation of cracks in the inspected material. Among the typical phenomena arising in the current TOFD inspection, the so-called «head wave» is the first contribution reaching the receiver. The head wave propagation on a planar interface is well known and identified as a critical refraction taking place on the material surface. On irregular surfaces, it has been shown that the head wave results from the melting of surface and bulk waves mechanisms and that surface irregularities are responsible for numerous diffractions of the incident head wave. To simulate such behaviour, a model has been developed using a ray tracing technique based on time of flight minimization (generalized Fermat's principle). It enables the calculation of the ray path and the corresponding time of flight of all waves propagating in the material, including the head wave. To obtain a complete propagation model for these waves (both trajectory and amplitude), the integration of Geometrical Theory of Diffraction (GTD) models is currently performed by coupling them with the ray-based approach discussed above.