Application of CF and DMAS Technology to Improve the Quality of Reflector Images Reconstructed from Echoes Measured by an Antenna Array

Reliability and sensitivity of ultrasonic control is determined by the noise level of the reflector image and its resolution. Application of CF- or DMAS-technology in various combinations is promising, as these technologies are simple enough, practically do not require additional computational resources, are applied to echo signals measured by conventional flaw detectors working with antenna arrays. In numerical and model experiments it is demonstrated that the application of these methods allows to increase the resolution of reflector images more than twice and to reduce the noise level by more than 20 dB. In the numerical experiment it is shown that phase distortions due to complex refractive and reflection coefficients lead to the fact that even with precisely known parameters of the experiment when working on a direct beam on a transverse wave the indication of the crack tip can shift from its true position by about a wavelength. For the solution of defectometry tasks this is a very large error. But, if phase correction is performed when reconstructing the reflector image, the crack tip indication coincides with its real position. CF- and DMAS-technologies have shown their workability also when working with noisy echoes.