IMAGING OF MECHANICALLY INDUCED THERMAL HEAT PATTERNS ABSTRACT

Imaging information obtained from nondestructive tests is becoming more widely investigated and developed. Imaging obviously has the potential to provide a more easily interpreted outcome of a nondestructive test, leading to more rapid and correct evaluation of the state of the examined material. This work presents one aspect of the field of imaging-- developing a thermal image of the surface of a material subjected to mechanical vibrations. The technique of vibrothermography has been under investigation in our laboratory for several years, especially as applied to advanced composite materials. We will present in this paper a review of the imaging aspects of the technique, in particular discussing the phenomena responsible for producing a surface heat pattern and the phenomena responsible for obtaining a suitable image of this pattern. Finally, a discussion is given of the possible interpretations which may be made from the image concerning evaluation of the material condition, as may be used in a nondestructive evaluation procedure. Examples will be drawn from a number of tests performed in our laboratory