The pulsed ultrasonic backscatter polar scan and its applications for NDT and material characterization

In a conventional ultrasonic polar scan (UPS) experiment, the amplitude or time-of-flight-diffraction (TOFD) values of the transmitted and/or reflected acoustic pulse are recorded for a wide range of incidence angles, in view of gaining knowledge about the elastic properties at the insonified material spot. Here we apply the pulsed UPS technique and investigate the backscattered signal, resulting in the ultrasonic backscatter polar scan (UBPS). It is shown that a UPBS contains a blueprint of geometrically related features of the insonified material spot which can be of particular interest for various industrial applications. We applied the UBPS for (i) the determination of the stacking sequence of a cross-ply composite laminate, (ii) the semi-quantification of a multidirectional microscopic surface corrugation, (iii) the detection of corrosion in an early stage as well as (iv) the detection and the localization of a closed surface breaking crack.