DETECTION OF WEAR CRACKS BY PHOTOTHERMAL RADIOMETRY

Among the non-destructive techniques, testing methods using thermal wa ves are starting to be developed in industry. Photothermal radiometry under cw excitation, which is one of these methods, has been used in t his work for the detection of wear cracks, either emerging on the surf ace of the sample or covered with a thin layer. Before conducting the experimental study, we have developed a three-dimensional mathematical model. It is shown that the influence of the flaw on the photothermal signal is indeed the result of two phenomena: a thermal barrier effec t and an optical effect owing to the higher emissivity of the crack wh en it is emerging.