Dp. Almond et Sk. Lau, DEFECT SIZING BY TRANSIENT THERMOGRAPHY .1. AN ANALYTICAL TREATMENT, Journal of physics. D, Applied physics, 27(5), 1994, pp. 1063-1069
Thermal edge effects for crack-like defects have been calculated using
the Wiener-Hopf technique. It is found that the crack surface tempera
ture is reduced over a distance of a thermal diffusion length by heat
flow around the crack edge to the cold underside of the crack. Surface
thermal images have been computed for a straight-edged and a circular
crack. Comparisons are presented of image profiles computed with and
without inclusion of edge effects. Edge effects lead to the prediction
that transient thermographic defect images should shrink with elapsed
time. Experimental data are presented, which are in agreement with th
is prediction and demonstrate a simple means of defect sizing.