'Gradient' polar scan technique for material characterization

In this paper, the concept of both the 'gradient' and the 'curvature' polar scan is introduced and illustrated for several carbon reinforced composites. While the conventional polar scan concerns the recording of the reflected or transmitted maximum amplitudes or TOFD values for a certain solid angle, here the differences between subsequent scan angles are considered. The quality of a polar scan experiment improves significantly, i.e. more defined and more detailed polar contours are obtained. Even more, several polar contours show up which were hidden in the conventional polar scan experiment. The amplitude and the TOFD recorded experiments suggest that both methods are complementary. For future quantitative modelling, i.e. to extract the elasticity constants Cij of the targeted material, this newly obtained technique can be of great importance.