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Proceedings Paper

Extraction of thermal Green's function using diffuse fields: a passive approach applied to thermography
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Paper Abstract

In the field of non-destructive evaluation, defect detection and visualization can be performed exploiting different techniques relying either on an active or a passive approach. In the following paper the passive technique is investigated due to its numerous advantages and its application to thermography is explored. In previous works, it has been shown that it is possible to reconstruct the Green’s function between any pair of points of a sensing grid by using noise originated from diffuse fields in acoustic environments. The extraction of the Green’s function can be achieved by cross-correlating these random recorded waves. Averaging, filtering and length of the measured signals play an important role in this process. This concept is here applied in an NDE perspective utilizing thermal fluctuations present on structural materials. Temperature variations interacting with thermal properties of the specimen allow for the characterization of the material and its health condition. The exploitation of the thermographic image resolution as a dense grid of sensors constitutes the basic idea underlying passive thermography. Particular attention will be placed on the creation of a proper diffuse thermal field, studying the number, placement and excitation signal of heat sources. Results from numerical simulations will be presented to assess the capabilities and performances of the passive thermal technique devoted to defect detection and imaging of structural components.

Paper Details

Date Published: 20 April 2016
PDF: 9 pages
Proc. SPIE 9803, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2016, 98030U (20 April 2016); doi: 10.1117/12.2218998
Show Author Affiliations
Margherita Capriotti, Univ. of California, San Diego (United States)
Simone Sternini, Univ. of California, San Diego (United States)
Francesco Lanza di Scalea, Univ. of California, San Diego (United States)
Stefano Mariani, Univ. of California, San Diego (United States)

Published in SPIE Proceedings Vol. 9803:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2016
Jerome P. Lynch, Editor(s)

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