NDTnet 1998 Aug, Vol.3 No.8

Abstract

The aim of this work is to provide a faster method than tomography to detect and characterize 3D flaws in mechanical parts. In the problem that this project address, the equipment must detect the defects using a simulated X-ray image computed from the CAD model. Then, the defects are reconstructed in 3D and characterized so that they can be localized in the object 3D CAD model. This paper presents the overall RADICAD methodology, it describes the projection, reconstruction and characterization tasks and gives some results.
Most CAD systems are capable of rendering 3D solid images, but, none can render realistic radiographs (1). The most innovative aspect of this work is the use of CAD models to generate synthetic images in the pose corresponding to the radiograph acquisition using raytracing techniques. The physics involved can be divided into three main parts: the X-ray source spectrum, the interaction of the radiation and the examined object and the detection system which have been anatically modelized. Further image processing techniques based on the comparison of radiographs and projections used as golden images allows to isolate, classify and reconstruct the flaws. A detection process generates mask images of the defects. These masks are used by the reconstruction process DARTS which implements a Simultaneous Algebraic Reconstruction Technique (2). to generate a support volume. Thus, only the defects are reconstructed. Then, characteristics as shape, density and position, are extracted and superimposed in the CAD model as shown on following figure.

Fig.: RADICAD methodology.



REFFFRENCES
1. F.InancJ.N. Gray, "New Developments in the Computer Simulation of X-ray Nondestructive Evaluation Process" Review of Prog in QNDE Vol 10A, Plenum Pub Co, pp 355-362, 1991
2. G. T. Herman, "Image Reconstruction from Projections. The fundamentals of Computerized Tomography. "Academic Press, 1980.

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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