NDTnet 1998 Aug, Vol.3 No.8

Abstract

In previous papers [1,2] we had described a radiographic image interpretation method based on an analysis of the different physical phenomena occuring at each step of the acquisition process : characteristics of the source, X-rays and material interaction in the object (scattering, beam hardening), detection. In the case of a mono-material object, this approach leads to a model linking the thickness of material crossed by the X-rays to the observed radiograph. By inversion of this model it is possible to build up a quantitative thickness map. Figure 1 shows a raw radiograph and figure 2 the corresponding thickness map obtained by inversion of the acquisition process. Let us note that this new representation of the radiograph looks sharper and more contrasted : the blur due to scattering has been removed and the beam hardening has been corrected.

By subtracting to this thickness map the theoretical thicknesses values given by a CAD model, we obtain a map representative of the defect's thickness. Figure 3 shows such a map for the circular weld area : the defects appears clearly on this image.
In the communication we will evaluate the increase of detection sensitivity and robustness obtained by detecting the defect on the thickness defect image in comparison to a detection limited to an analysis of the raw radiographs.

Figure 1 : Raw radiograph ; Figure 2 :Thickness map ; Figure 3 :defect's thickness map

References :
[1] "Beam Hardenning and Scattering Correction for a Quantitative X-Rays Inspection of Fuel Rods", F. Retraint, 1M Dinten, Proceedings of Review of Progress in Quantitative NDE, 1996, Brunswick, USA
[2] "Quantitative X-Ray Inspection", F. Retraint, J.M Dinten, R. Campagnolo, F. Peyrin, Proccedinas of Review of Proaress in Ouantitative NDE-1997, San Diego, USA

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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