Abstract : The ability of an adaptive ultrasonic imaging procedure to inspect
inside unknown anisotropic nuclear steels, such as V-shape welds or cladded components, is investigated herein. The
optimization scheme combines the Total Focusing Method (TFM) imaging algorithm with a customized
gradient ascent method in order to improve both the quality and reliability of ultrasound images.
A statistical analysis of its robustness is performed with simulated echoes and using a surrogate
model in order to speed up the computation times of TFM images. Then, the optimization procedure is
evaluated on several experimental cases and it provides highly enhanced images with a 5 MHz
array. The positioning of the artificial defects of 1.5 mm diameter is estimated with less than 1
mm error with respect to their actual positions, and the signal-to-noise ratio is increased by up to
10 dB. The elastic properties are also estimated with less than 10% error when compared to actual
material properties.
