Thermal non-destructive characterization

by thermal input impedance

A. Tmiri, S. Belattar*, S. Sahnoun

Laboratoire d’Energétique et de Traitement de Signal

Département de Physique, Faculté des Sciences

24000 El Jadida - Maroc

* Corresponding author. E-mail : belattars@ucd.ac.ma

Received 02 November 2000

Abstract

Classical thermal non destructive testing is a technique for obtaining surface temperature profile in a structure. It can reveals the presence of a flaw by observation of the temperature distribution profile anomaly which the flaw produces on the surface of the structure. Indeed, a flaw inside the structure will generally alter the heat flow through the structure due to the difference in its heat transfer properties and those of the unflawed structure. If the heat flow pattern is sufficiently altered, a difference of temperature on the structure in the unflawed and the flawed regions is observed. In consequence, a difference in input thermal impedance, defined in frequency domain like the report of temperature variations and the heat flow variations at the input structure, between the areas with and without flaw will be observed too. The frequency analysis of this thermal input impedance permits to characterize the structure to be inspected. We limit our study, in this paper, to a one-dimensional heat conduction assumption. The simulations realized according to the position of the defect in the structure and the frequency treat several situations depending on the geometry and the thermophysical characteristics of the structure considered.

Keywords : Diffusivity; Effusivity; Thermal impedance; Temperature; Heat flow; Non-destructive testing.

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