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Proceedings Paper

Flash thermography with a periodic mask: profile evaluation of the principal diffusivities for the control of composite materials
Author(s): Leonardo Spagnolo; Jean-Claude Krapez; Martin Friess; Hans-Peter Maier; Guenther Neuer
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Paper Abstract

Recently we proposed a modification of the classical flash thermography method for diffusivity measurement: by putting a mask having a periodic pattern of apertures between the flash lamp and the orthotropic material to be tested, one can obtain simultaneously the out-of-plane diffusivity and the in-plane diffusivity of the material. Here we present two examples where the measurement of the thermal properties is made at a local level: the experiment is performed with a large grid mask, however the parameter identification is made on a sliding window whose width corresponds to one-period of the mask. By this way, one can get a profile for each diffusivity. By applying this procedure, one can expect detecting localised variations of the thermal properties, as well as cracks. We controlled by this way a series of C/C-SiC dog-bone samples during a tensile test. We systematically observed a rather uniform and linear decrease of about 0.1%/MPa for the in-plane diffusivity. This behaviour is related with the fact that a stress increase induces a gradual increase of the microcracks density. The second example deals with carbon disk brakes control. By using a circular mask, one can get in about two minutes the circumferential profile of both in-plane and out of plane diffusivities of the composite piece.

Paper Details

Date Published: 1 April 2003
PDF: 9 pages
Proc. SPIE 5073, Thermosense XXV, (1 April 2003); doi: 10.1117/12.487552
Show Author Affiliations
Leonardo Spagnolo, Politecnico di Bari (Italy)
Jean-Claude Krapez, ONERA (France)
Martin Friess, DLR (Germany)
Hans-Peter Maier, Univ. Stuttgart (Germany)
Guenther Neuer, Univ. Stuttgart (Germany)

Published in SPIE Proceedings Vol. 5073:
Thermosense XXV
K. Elliott Cramer; Xavier P. Maldague, Editor(s)

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