Inspection of Complex Geometries using Flexible Phased-Array Transducers

Abstract

The piping inspection in nuclear power plants uses ultrasonic techniques, and their implementation is often performed with contact methods. The control is efficient, and the transmission is maximized when the wedge of the transducer is adapted to the surface of the component. However, the fixed shape of wedge can not be matched to all inspected zone when the component presents a variable surface (elbow, no zzles, butt weld…). In that case, the transmitted field is more or less disturbed and can lead to wrong flaw localization and characterization. To optimize the contact inspection with this type of component, flexible phased-array techniques have been developed, taking advantages from instrumentation and software developments. Firstly, the CIVA software is used to design the element arrangement and to evaluate its ability to detect defects. In operatio n, an embedded instrumentation measures in real time the current shape of the emitting s urface. From this data, the M2M acquisition system calculates in real time the delay la ws to be applied to the elements to compensate the deformation and thus to control the beam characteristics during the displacement of the probe. This first part of this paper presents experiments carried out to inspect a 2D real profile mock-up including artificial defec ts. Performances are evaluated using recent developments of the embedded algorithm to calcu late delay laws in real time (multi-shot configuration). The second part shows examples of industrial inspections of a complex 3D mock-up using the 3D flexible array piloted by a robot. CIVA software reconstruction functionalities are also presented to r econstruct acquisition data according to the embedded parameters.