An example of using an AUGUR-ART flaw detector to visualize the entire section of a plexiglass CO-1 sample using CFA-X processing (combining digital antenna focusing and mechanical scanning) is shown. A significant increase in the signal-to-noise ratio is shown when using phase-manipulated complex signals
It is proposed to use the maximum entropy (MME) method to reconstruct the image of reflectors from echo signals measured in the TOFD mode in order to increase the accuracy of determining the size of the discontinuities of the control object. The calculation of the echo signal reflected from a point reflector at an arbitrary depth in the TOFD mode was carried out. For verification, the results obtained in numerical modeling were compared with the results of calculating a similar model using the CIVA program. Using the example of images obtained in numerical and model experiments, the influence of the factor of changing the shape of echo signals on the results of the ME method is studied. As the study showed, the variable waveform imposes a restriction on the use of this super-resolution method, which was the reason for the subsequent modification of the image recovery algorithm by the ME method. This modification made it possible to visualize inhomogeneities in the material of the object of control more qualitatively.
For the calculation of echo signals during numerical experiments of ultrasound control, the finite difference method in the time domain (CRVO) can be used. Since the KRVO method is based on an explicit numerical solution of the wave equation for an elastic medium, it takes into account such effects as the occurrence of a run-around wave on a volumetric reflector, the effects of the transformation of a longitudinal wave into a side wave when ultrasound is scattered on a crack, the scattering of pulses between reflectors and the boundaries of the object of control. The numerical solution of the vector wave equation by the KRVO method, in contrast to the modeling methods based on the theory of ray tubes, allows you to more accurately simulate the results of ultrasonic testing. The article considers three solutions to the problem of suppressing the reflection of pulses from the boundaries of the computational grid. Calculation of the direct problem of propagation of elastic vibrations in a solid by the KRVO method may be useful for solving the coefficient inverse problem of ultrasonic non-destructive testing.
To develop methods of ultrasonic inspection of such complex objects as composite seams, the method of finite differences in the time domain (CRVO) can be used to calculate echo signals in numerical experiments. Since the KRVO method is based on an explicit numerical solution of the wave equation for an elastic medium, it takes into account such effects as the occurrence of a run-around wave on a volumetric reflector, the effects of the transformation of a longitudinal wave into a side wave when ultrasound is scattered on a crack, the scattering of pulses between reflectors and the boundaries of the object of control. The application of the KRVO method for modeling the propagation of ultrasound in a sample with high structural noise and in samples of anisotropic inhomogeneous materials is justified. Calculation of the direct problem of propagation of elastic vibrations in a solid by the KRVO method may be useful for solving the coefficient inverse problem of ultrasonic non-destructive testing.
The article proposes a method for determining the velocity of a longitudinal ultrasonic wave in a homogeneous welded joint, based on a comparison of measured and calculated echo signals reflected from the bottom of the control object using two antenna arrays on prisms operating in double scanning mode. The influence of errors in setting parameters such as the distance between antenna arrays, the thickness of the control object and others on the accuracy of calculating the wave velocity in a welded joint is analyzed. The results of numerical and model experiments on the calculation of the wave velocity in a welded joint are presented. Using the developed method in the model experiment, it was possible to measure the velocity of the longitudinal wave in the welded joint model with an error of less than 0.7%. The proposed method can be used to find the initial approximation in the nonlinear inverse problem of tomographic diagnostics of welded joints in the wave approximation
The report presents information on the development and pilot operation of an automated ultrasonic control system with a full automation cycle based on phased antenna arrays together with the ultrasonic inspection technique of annular welded joints of steam generator shells PGV-1000, PGV-1000M. Information about automation algorithms and their results are given work on real welded joints containing permissible discontinuities and on test samples containing unacceptable discontinuities. All stages of automation at the stages of setting up, collecting and analyzing ultrasound control data are shown.
Based on the analysis of the results obtained during the implementation of the pilot operation program, it was found that the use of the system and methodology for operational control of NPP equipment and pipelines is justified.
To control the thickness of pipelines with non-equidistant surfaces (for cone junctions with a large thickness difference and for the area under the weld reinforcement roller), a technology for constructing a bottom surface profile based on the ultrasonic method using digital antenna focusing (CFA) has been developed. The method is based on the emission of ultrasonic waves in the OK and the registration of these ultrasonic waves reflected from the internal boundaries of the OK, as well as subsequent digital processing of the CFA with the formation of images from the recorded signals.
The control of welded joints in the main shut-off valves of the first circuit of the VVER-440 reactor plant (GPP) is difficult due to the high level of structural noise and the need to use pulses reflected once from the inclined bottom of the branch pipe. Carrying out the control on the longitudinal wave leads to the appearance in the reconstructed image of the reflectors of false glare formed by pulses on the transverse wave. Since the amplitude of false glare can be commensurate with the amplitude of glare obtained on longitudinal waves, the analysis of such images can be difficult. To improve the image quality, it is proposed to register echo signals using thinned antenna arrays and apply three-dimensional processing of echo signals. Numerical and model experiments have shown that this approach increases the frontal resolution in the additional plane several times and reduces the amplitude of false glare, which makes it possible to increase the sensitivity and reliability of expert ultrasonic control of the main gate valve.
The results of the certification of the continuous thickness measurement technique of NPP pipelines are presented. The description of the equipment used with the support of FR and EMAP technology is given. To measure the thickness of straight sections, cone junctions and bends with 100% data recording, FR flaw detectors such as AUGUR ART, Omniscan, Harfang, Gecko with two-coordinate scanning devices are used. To measure the profile under the weld reinforcement roller, the TOFD method is used, implemented using phased arrays.