A hybrid method combining the surface integral equation method and ray tracing for the numerical simulation of high frequency diffraction involved in ultrasonic NDT

Ultrasonic Non-Destructive Testing (US NDT) has become widely used in variousfields of applications to probe media. Exploiting the surface measurements of the ultrasonicincident waves echoes after their propagation through the medium, it allows to detect potentialdefects (cracks and inhomogeneities) and characterize the medium. The understanding andinterpretation of those experimental measurements is performed with the help of numericalmodeling and simulations. However, classical numerical methods can become computationallyvery expensive for the simulation of wave propagation in the high frequency regime. Onthe other hand, asymptotic techniques are better suited to model high frequency scatteringover large distances but nevertheless do not allow accurate simulation of complex diffractionphenomena. Thus, neither numerical nor asymptotic methods can individually solve highfrequency diffraction problems in large media, as those involved in UNDT controls, both quicklyand accurately, but their advantages and limitations are complementary. Here we propose ahybrid strategy coupling the surface integral equation method and the ray tracing method tosimulate high frequency diffraction under speed and accuracy constraints. This strategy isgeneral and applicable to simulate diffraction phenomena in acoustic or elastodynamic media.We provide its implementation and investigate its performances for the 2D acoustic diffractionproblem. The main features of this hybrid method are described and results of 2D computationalexperiments discussed