Multiple scattering filter: application to the plane defect detection in a nickel alloy

摘要

The ultrasonic inspection of polycrystalline media remains a challenge. The high noise levels due to the interaction between the wave and the microstructure limit the efficiency of classical ultrasonic techniques to detect a defect in a coarse grain structure. The aim of this work is to reduce the influence of multiple scattering in order to increase the information obtained from the defect. The technique introduced in this presentation is based on array probes for the acquisition of the medium's response matrix by full matrix capture, after which a filter based on random matrix theory is applied. Here the technique is used on a nickel alloy block that presents an unfavourable grain structure and a well known plane defect. In this paper, the results of this new technique, with an angle array probe of 128 elements and 5 MHz of central frequency are compared to classical phased array probe techniques.