NDTnet 1998 Aug, Vol.3 No.8

Abstract

The CEA (French Atomic Energy Commission) has developed an adaptive system based on phased array techniques: the F.A.U.S.T. (Focusing Adaptive UltraSonic Tomography) system. This system aims at improving the performances of nondestructive examination, particularly for what concerns the adaptability to different control configurations and defect characterization. This technique relies on the use of phased array transducers dynamically controlled by a multi-channel acquisition system, supplying both amplitude and delay laws to form the ultrasonic beam. A diffraction model, predicting the ultrasonic field radiated through a liquid-solid interface, is used both to design arrays of optimized shape and to calculate theoretical acoustical laws according to the control conditions. The information received by each ultrasonic channel can be stored, enabling various reconstruction and imaging processes. This storage capability coupled to an electronic control of the phased array transducer allows to adapt in real-time the system to the control configuration.

Two applications dedicated to realistic control conditions are presented in this paper showing the adaptability of the system. Both applications concern the inspection of steel specimens with varying profile. In each case, the objective is to improve defect characterization by controlling the effect of the varying surface on the refracted ultrasonic beam. At each scanning position, adapted delay laws, provided by the diffraction model, are used to preserve the orientation and the depth focusing of the ultrasonic beam. In the first case, the inspected profile is representative of a weld misalignment, made of two horizontal planes joined by an inclined plane. In the second case, the profile varies smoothly from a plane to a cylindrical surface. Experimental results show the feasibility of these techniques.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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