Applications of Laser-Ultrasonics to the Automotive Industry

Laser-ultrasonics, which uses lasers for the genera tion and detection of ultrasound is now a mature nondestructive technique for evaluation of m aterials and structures. This technique works at a distance, without surface preparation, and is then specially adapted to inspect moving and hot parts of complex geometrical shapes. Applicatio ns of laser-ultrasonics to the automotive industry have been rarely reported, and this paper is aimed to present some applications developed at the Industrial Materials Institute of the National Research Council of Canada. A first application is the evaluation of weld integri ty. Welds produced by different methods such as laser stitches, spot welding, friction stir welding as well as conventional MIG welding were tested by the technique, and some examples are pres ented. A second application that has been explored is the evaluation of the magnesium/aluminu m interface of a novel engine crankcase casting, in which delaminated and well bonded zones were clearly separated in the laserultrasonic images. A third application is the measu rement of paint thickness, not only when it is dried but also following application when it is sti ll wet. For this application, thickness can be obtained following a spectroscopic analysis of the laser-ultrasonic data. Finally, adhesive bonding is a new trend in the automotive industry a nd results are presented on the assessment of bond strength.