Recent Advances in Adaptive Imaging for Ultrasonic Inspection of Complex Geometry Components

Speaker:
Robert, Sébastien; CEA-LIST; France

Authors:
Cartier, F.; CEA, LIST; France
Robert, S.; CEA, LIST; France
Saint-Martin, V.; CEA, LIST; France

ID: ECNDT-0382-2018
Session: PAUT-Signal processing
Room: G2
Date: 2018-06-13
Time: 16:00 - 16:20

The present communication describes the latest advances in adaptive ultrasound imaging with ATFM (Adaptive Total Focusing Method) for the inspection of complex geometry components. For the method to be usable, the phased-array probe is either immersed in water or equipped with a water-filled elastomer wedge able to conform to the complex geometry. The principle consists in recording a set of pulse-echo signals according to the FMC (Full Matrix Capture) array sequencing or derived acquisitions, and then these signals are processed twice. The TFM imaging algorithm is first applied to the FMC database to image the complex surface and to extract its geometry. Once the surface profile has been determined, a second TFM image is calculated in the specimen with a ray-based forward model that is compatible with a real-time computation of times of flight through the complex water/solid interface.
In this communication, we present some optimizations of the embedded ATFM algorithms to deal with highly perturbed surface geometries. Furthermore, ATFM is extended to half-skip imaging modes to improve the characterization of cracks under irregular surfaces. To do this, phased-array probes are equipped with angled conformable wedges (eg.: L60 or T45 wedges). Finally, the ATFM images are formed in real-time with a prototype version of the portable M2M systems, and experiments are carried out with mock-ups, the geometries of which are representative of complex nuclear components.