INVESTIGATION PARAMETERS ULTRASONIC DEVICE ON PHASED ARRAYS. FOCUSING MODES FOR ULTRASONIC DEVICE TYPE OF OMNISCAN

Abstract

The article is devoted to possibilities of regular focusing of Omniscan device on phased arrays. Questions are raised about evaluation of testing results when using linear and sector scan-ning with different focus parameters. The question of size near-field for phased arrays and asso-ciated choice of focus mode is discussed. The article is based on experiments conducted on samples with artificial reflectors at the same size, but different in type: a non-directional reflector (a side-drill hole) and a directional reflector (a flat-bottomed reflector), located at the same depth. The study was conducted for transducers with different frequencies. Families of curves of the signal amplitude dependence are obtained: on depth reflector, on focus depth setting, and on type reflector. The results emphasize need for precise focusing with-in the near-field of the transducer for small thicknesses or shallow depth of occurrence of discontinuities, and large variability in choice of focusing for depths in far-field. The study notes a significant difference in values of depth reflector at different focusses at a fixed position of transducer. In this article, in addition to considering possibility of focusing a flaw detector with phased arrays, the focus is on interpretation of results and reliability of testing in the analysis and comparison data. An integral part of the technological testing protocol for phased array is the depth of focus and the type of scanning. The obtained data do not depend on the frequency of transducer, which means that conclusions are applicable to general range of flaw detectors on phased arrays.