Bazulin E.G.,Scientific and Production Center
Russian Journal of Nondestructive Testing | Year: 2010
The influence of the effect of nonspecular reflection of transverse ultrasonic waves from the boundaries of a test object on the quality of coherent images of flaws is considered. The existence of an effect of nonspecular reflection in a pulsed operating mode and the accuracy of its description within the framework of complex reflection coefficients is experimentally verified. It is shown that the effect does not influence the delay times of propagating pulses and only the amplitude of echo pulses changes. Such distortions slightly impair the quality of flaw images that are reconstructed by coherent methods. Nevertheless, the methods for eliminating the influence of this effect are considered for two methods, viz.; FT-SAFT and SAFT. Images of flaws that were reconstructed by the FT-SAFT method without taking the nonspecular reflection effect and with its compensation into account are presented. © 2010 Pleiades Publishing, Ltd.
Bazulin E.G.,Scientific and Production Center Echo
Russian Journal of Nondestructive Testing | Year: 2011
The application of antenna arrays (AAs) for obtaining flaw images during automated non-destructive testing is considered. The conventional technique of using an AA as a phased AA has a number of drawbacks. An alternative approach is proposed in which echo signals are registered using an AA operating in the double scanning mode, and a modified algorithm of the combined SAFT, which takes into account multiray ultrasound propagation with consideration of transformations of wave types upon reflections from irregular boundaries of a test object, is used to obtain flaw images. The results of testing a specimen with a model of a volumetric flaw in the form of a 2-mm-diameter side hole drilled at a depth of 12 mm and a specimen with a crack model with a tip at a 12-mm depth are presented. Both specimens have rough bottoms. The obtained images allow determination of not only the dimensions and locations of flaws, but also their type. © 2011 Pleiades Publishing, Ltd.
Bazulin E.G.,Scientific and Production Center |
Ismailov G.M.,Scientific and Production Center
Russian Journal of Nondestructive Testing | Year: 2013
Methods for the determination of the unknown velocity of the propagation of shear US waves and the unknown thickness of a test object were considered. Two antenna arrays working in the double-scanning mode, where echo signals are recorded, which were emitted and received by all pairs of antenna-array elements, were suggested. Antenna arrays on prisms were mounted on the test-object surface towards each other. An algorithm for the treatment of measured echo signals was designed using a method that is similar to the least-squares method. The use of the algorithm enables one to simultaneously determine the sound velocity and thickness of a test object with plane-parallel boundaries with an exactness greater than 0.5%. In this article, the factors were studied that affect the exactness of measurements and methods of their elimination or minimization. The results of numerical experiments and the use of the method on three samples relative to measurements using an IN-5101A instrument are given. © 2013 Pleiades Publishing, Ltd.