NDTnet 1998 Aug, Vol.3 No.8

Abstract

The principle disadvantage that non-destructive testing by ultrasonics presents in relation with radiography is that the defect is not visualised but deduced from a signal [1]. The visualised electric signal is obtained from the transformation and the processing of a ultrasonic signal after its interaction with the defect. Each element of the testing chain influences the signal, thus the testing results. We intend to study the influence of instrumentation on the signal in order to avoid any erroneous interpretations and to optimise the parameters of each element to improve the precision and the fiability of the testing by ultrasonics. ln our paper, we describe the installation we realised for this [2]. This installation, piloted by a computer, permits to measure the electrical and acoustical parameters influencing the testing. We give experimental results obtained with this installation . A signal spectrum of a transducer .The constructor gives a frequency of 10 MHz. The real frequency (fig.l) is 8.6 MHz. With this installation we have visualized the transducers acoustical beams. We give an example of sections cut of acoustical beam of a transducer with a linear focalisation (fig.2). A computational program for measure apparatus command and for signal processing and the creation of a data bank has been realized These data permit, on the one hand, to detect any modifications in the parameters due to adeteriorational or to an electronical derive, and on the other hand, to realize a computational simulation program permitting to choose the best configuration of the chain for the testing of the welded joints (pipelines...etc).

Fig. 1 Signal spectum	Fig. 2 Sections cut of acoustical beam

References:
[1] E. Diealesaint et D. Royer, Ondes elastiques dans les solides. Application au traitementdu signal, Editions Mason & Cie. 1974
[2).A. Badidi Bouda & T. Meksen: Caracterisation de l 'instrumentation utilisee encontrole des materiaux par ultrasons. Lebanese Scientific Reasearch Reports 1997.

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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