Fast numerical calculations of 3-D phased array wave fields based on transient point source synthesis

The increasing interest in ultrasonic phased array techniques for non-destructive evaluation (NDE) and structural health monitoring (SHM) applications is based on the fact that reasonably priced and easy-to-use transducers and multi-channel measuring systems become more and more available. As a consequence the need for fast and reliable modelling tools for the design and optimization of phased array wave fields is also increasing. While semi-analytical methods for wave field synthesis are usually very fast but often suffer from several approximations like neglect of near-field effects, multiple scattering, and mode conversions, purely numerical methods include all relevant wave phenomena but are characterized by significantly larger computation times and memory requirements, especially in 3-D. In the present paper a new hybrid method is presented which combines the Elastodynamic Finite Integration Technique (EFIT) with the concept of transient point source synthesis. As a result broadband 3-D ultrasonic wave fields generated by arrays of connected and distributed transducers can be calculated within a few seconds on a common PC. We present various examples of application including high-frequency phased arrays for volume inspection and lowfrequency guided wave arrays. We also discuss how the proposed technique can be expanded to multi-layers and anisotropic media.