Simulation of ultrasonic inspection of complex components using a 3D-FDTD-approach

Nondestructive testing of rails, pipelines and other structures is of strong interest in evaluating the integrity of components. Preparation of inspection procedures for such complex structures with simulation is of great importance to understand the ultrasonic wave behaviour and influencing factors, to optimize NDT configurations and to save time and cost. This contribution reports on the three-dimensional simulation of elastic wave propagation using Finite Difference Time Domain (FDTD) method. The equations of motion and the stress strain relations completely define the elastic wave motion in the considered media. The numerical model has been successfully implemented and tested for numerous cases involving phased array and circular transducers in steel specimens in immersion and contact technique. Model defects such as flat-bottomed holes or side-drilled holes have been simulated. The work presented here also addresses the use of GPGPU (General Purpose computation on Graphical Processing Units) in taking advantage of massive data parallelism innate to the FDTD approach. The results show a strong improvement in the speed of computation in comparison to serial execution on CPU. We show representative results, also in comparison against simulated data obtained by a validated semi-analytical approach.