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Proceedings Paper

Inspection and evaluation of laser welds for transit buses
Author(s): Hsin Wang; Zhili Feng; Phil S. Sklad
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Paper Abstract

Laser welds in light-weight transit bus panels were studied by IR imaging. The corrugated structural panels were made from 3mm thick stainless steel. The panels were welded by a high power laser with lines of equally spaced 1” stitches. After discovering problems by visual and tapping inspections, the panels were sent to our laboratory for further investigation. The IR thermography method was chosen to study the welds because of its non-contact nature and potential for large area, high-speed inspections. We used thermophysical properties of the panels and finite element modeling to predict temperature variations of “good” and “bad” welds. Surface heating and “heat leak” methods were used to inspect each weld. The IR images clearly showed characteristic temperature signatures of “good” and “bad” welds. We also discovered a number of partial welds and questionable welds. In the follow-up destructive inspection, the welds interfaces were imaged and related to the infrared images. None or partial penetrations were found on a number of bad and partial welds. Even in the good welds, the weld stitch appeared to be discontinuous. This study helped the bus manufacturer to assess their welding process and make necessary improvement.

Paper Details

Date Published: 12 April 2004
PDF: 8 pages
Proc. SPIE 5405, Thermosense XXVI, (12 April 2004); doi: 10.1117/12.543920
Show Author Affiliations
Hsin Wang, Oak Ridge National Lab. (United States)
Zhili Feng, Oak Ridge National Lab. (United States)
Phil S. Sklad, Oak Ridge National Lab. (United States)

Published in SPIE Proceedings Vol. 5405:
Thermosense XXVI
Douglas D. Burleigh; K. Elliott Cramer; G. Raymond Peacock, Editor(s)

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