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Proceedings Paper

Detection of tightness of mechanical joints using lock-in thermography
Author(s): Thomas Zweschper; Datong Wu; Gerhard Busse
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Paper Abstract

Lockin thermography is currently being used for the rapid and remote identification of subsurface structures and defects such as impact damages, delaminations, and hidden corrosion. The purpose of this paper is to show that lockin thermography is also a reliable tool to inspect in a remote way the tightness of mechanical joints in safety relevant structures (e.g. aerospace equipment and vehicles). For example, the rapid identification of loose rivets is a major concern for airlines and manufacturers in order to monitor the structural integrity of their aircraft. Our measurements aimed at the early detection of loose rivets. We analyzed the phase image signature obtained on two metal plates pressed together by screws fastened at various torque levels. A clear relationship was established between phase angle and torque level at which the screws had been fastened. Based on these results our investigations were extended to riveted samples where two aluminum plates were pressed together by an array of ten blind rivets. Also in this case the level of tightness of rivet joints can be detected. In addition to these feasibility studies on model samples, we performed investigations on airplane components which confirmed the applicability of lockin thermography for remote maintenance inspection within a few minutes.

Paper Details

Date Published: 10 September 1999
PDF: 6 pages
Proc. SPIE 3827, Diagnostic Imaging Technologies and Industrial Applications, (10 September 1999); doi: 10.1117/12.361014
Show Author Affiliations
Thomas Zweschper, Univ. Stuttgart (Germany)
Datong Wu, Robert Bosch GmbH (Germany)
Gerhard Busse, Univ. Stuttgart (Germany)


Published in SPIE Proceedings Vol. 3827:
Diagnostic Imaging Technologies and Industrial Applications
Jorma Lammasniemi; Herbert Wiggenhauser; Gerhard Busse; Bruce G. Batchelor; Wolfgang Poelzleitner; Gerd Dobmann, Editor(s)

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