Advanced Matrix Phased Arrays Settings for Inspection

Phased arrays are now widely used in ultrasonic non destructive testing, as they provide improved versatility with comparison to conventional monolithic probes. Apart from the intrinsic abilities to steer and to focus the beam through planar, curved or irregular profiles, specific phased arrays acquisition schemes can also be applied. Electronic commutation (a group of elements over a large array transmits the ultrasonic beam, then neighboured elements are activated) allows very fast inspection times – this may be performed, for instance, for pipes inspections using circular arrays -, while sectorial scanning (several delay laws are applied to sweep the beam at different refraction angles) allows to inspect a given area without mechanical motion of the probe, which may be applied for access-limited components (turbine inspections for instance). Although these techniques are quite well known in the NDT field, most applications have been carried out with linear phased arrays (1D phased arrays). More complex applications now require advanced phased array techniques based on matrix array design, which imply increased number of elements and improved phased arrays driving software and systems. Developments carried out at CEA and M2M aim at providing user-friendly tools to conceive and to fully exploit electronic commutation and scanning features over matrix arrays (2D phased arrays), for which one can easily define groups of transmitters and receivers, draw their electronic scanning trajectories in the full array pattern, and modify their active aperture as well as applied delay laws at transmission and/or reception. The collected data may therefore be displayed in the real component frame thanks to 3D CAD features based upon paths associated to each ultrasonic shots carried out during the acquisitions. Several simulations of inspection configurations performed over complex components (nozzles, CAD specimen...) are presented, which illustrate some potential applications of matrix array settings