NDTnet 1998 Aug, Vol.3 No.8

Abstract

Societe Europeenne de Propulsion (SEP) has developped for more than 20 years a great variety of materials with different thermal and mechanical properties. They are used industrially for numerous applications in the field of aeronautic and space. Thus, all the parts must be inspected with adapted non destructive techniques. SEP has been using for more than 10 years Holographic Interferometry (HI) using a thermoplastic camera in order to inspect parts made in elastomer and also bonded structures. New techniques, Electronic Speckle Pattern Interferometry (ESPI) and Shearography have, emerged in the last years as a powerful new tool for the nondestructive inspection. These techniques can be used in place of HI.

ESPI and shearography have different advantages compared to HI: real time inspection, images digitalization and long time stockage on CD ROM without damage, limited cost of control (no film, only CD-ROM). Images can be improved: noise reduction, normalization, measurement of defects. We have tested and performed those three techniques on different elastomer parts with simulated defects. In this paper, after a description of different techniques used, of SEP equipment and of material tested, we present qualitative and quantitative results obtained on parts and coupons with simulated defects. Then we compare the technical and economical performance of both techniques.

Fig.1 ; Fig.2

Figure 1 and figure 2 depict results obtained by ESPI and shearographie performed on the same elastomer part with 2 flaws. The level of noise is better with the second technique.

Shearography provides at least the same performance as HI and cuts the cost of the inspection. Moreover data can be stored for a long time without a degradation of the medium. Thus, for all these reasons SEP decided to replace the HI inspection by shearography.

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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