CREEPING SURFACE LONGITUDINAL ACOUSTIC WAVE: MAIN PROPERTIES AND APPLICATION POSSIBILITIES

2021 ◽  
pp. 4-12
Author(s):  
V. G. Shevaldykin
Keyword(s):  
Critical Angle ◽  
Flaw Detection ◽  
Ultrasonic Signal ◽  
Ultrasonic Waves ◽  
Concave Surface ◽  
Ultrasonic Tomography ◽  
Transverse Waves ◽  
Near Surface ◽  
The Third ◽  
Creeping Wave

Creeping ultrasonic waves have long been successfully used for flaw detection of near-surface and near-bottom zones of metal products. However, due to the fact that the creeping wave generates a lateral transverse wave directed into the metal volume at the third critical angle, it is also possible to test internal defects in principle. At known velocities of propagation of longitudinal and transverse waves in the metal, the third critical angle is easily calculated. Therefore, the time of propagation of the ultrasonic signal along any trajectory between points on the surface and in the volume of the metal can be calculated. Usually, creeping waves are used to test products of plane-parallel shape. There are no cases of their application on curved surfaces in the literature. It is possible that the creeping wave can also propagate over a concave surface. The aim of the article is to test experimentally new ways of using creeping waves. The propagation trajectories of the creeping and lateral transverse waves were studied on a steel plate. The time of passage of the ultrasonic signal along such trajectories of different lengths was measured, and the measurement results were compared with the calculated time values. The measured and calculated values coincided with accuracy sufficient for the coherent accumulation of echo signals that passed through the metal part of the path by the creeping wave and another part of the path by the lateral transverse wave.The propagation of the creeping wave over a concave surface was studied on a steel sample with cylindrical faces of different radii. As a result, it turned out that on a concave surface, the creeping wave propagates at the same speed of longitudinal waves as on a flat surface, but it decays much more strongly with distance. Studies have shown that creeping waves can be used in ultrasonic tomography, where a preliminary calculation of the propagation trajectories of ultrasonic signals is required. The propagation of creeping waves over concave surfaces extends the capabilities of the TOFD method to the area of intube testing

Near surface flaw detection by ultrasonic critical angle imaging

1982 ◽  
Vol 3 (4) ◽  
pp. 201-220 ◽  
Author(s):  
G. L. Fitzpatrick ◽  
B. P. Hildebrand
Keyword(s):  
Critical Angle ◽  
Flaw Detection ◽  
Surface Flaw ◽  
Near Surface

Study of the ultrasonic creeping wave propagation over a concave metal surface

2021 ◽  
Vol 87 (8) ◽  
pp. 23-28
Author(s):  
V. G. Shevaldykin
Keyword(s):  
Wave Propagation ◽  
Metal Surface ◽  
Time Of Flight ◽  
Diffraction Method ◽  
Ultrasonic Waves ◽  
Radius Of Curvature ◽  
Cylindrical Shape ◽  
Near Surface ◽  
Time Of Flight Diffraction ◽  
Creeping Wave

Creeping ultrasonic waves are used in echo flaw detection of near-surface and near-bottom zones of metal products of plane-parallel or cylindrical shape. The creeping (lateral) waves are also used in testing products by the time-of-flight diffraction method as the earliest (reference) signal, followed by the useful signals of waves diffracted on metal discontinuities. The purpose of this study is to evaluate the ability of the creeping wave to propagate over a concave metal surface. We have studied experimentally the attenuation of the amplitude of a creeping wave with the distance upon wave propagation over concave metal surfaces of different radii. The velocity of propagation of the creeping wave does not depend on the radius of curvature and equals to the velocity of the bulk longitudinal wave. The results obtained provide the possibility of using the time-of-flight diffraction method in control of the objects with concave surfaces, in particular, for in-tube testing.

scholarly journals Analysis of Flaw Detection Sensitivity of Phased Array Ultrasonics in Austenitic Steel Welds According to Inspection Conditions

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 242
Author(s):  
YoungLae Kim ◽  
Sungjong Cho ◽  
Ik Keun Park
Keyword(s):  
Austenitic Steel ◽  
Simulation Modeling ◽  
Power Plants ◽  
Phased Array ◽  
Flaw Detection ◽  
Wave Mode ◽  
Ultrasonic Waves ◽  
Detection Sensitivity ◽  
Flaw Sensitivity ◽  
Steel Welds

The anisotropy and inhomogeneity exhibited by austenitic steel in welds poses a challenge to nondestructive testing employing ultrasonic waves, which is predominantly utilized for the inspection of welds in power plants. In this study, we assess the reliability of phased array ultrasonic testing (PAUT) by analyzing the flaw detection sensitivity of ultrasonic beams in anisotropic welds, based on the inspection conditions. First, we simulated the sectorial scan technique, frequently employed for the inspection of actual welds, while taking into account the ultrasonic wave mode, frequency, and shape and position of a flaw. Subsequently, we analyzed the flaw sensitivity by comparing A-scan signals and S-scan results. The sensitivity analysis results confirmed the detection of all flaws by considering at least two inspection methods based on the shape and position of the flaw. Furthermore, we verified our model by performing an experiment under the same conditions as the simulation and found that the results were in agreement. Hence, we find that the simulation modeling technique proposed in this study can be utilized to develop suitable inspection conditions, according to the flaw characteristics or inspection environment.

Imaging Cracks in Bones Using Acoustic Nonlinearity: A Simulation Study

2011 ◽  
Vol 97 (5) ◽  
pp. 728-733
Author(s):  
Yang Liu ◽  
Xiasheng Guo ◽  
Zhao Da ◽  
Dong Zhang ◽  
Xiufen Gong
Keyword(s):  
Time Reversal ◽  
Three Dimensional ◽  
Harmonic Component ◽  
Ultrasonic Signal ◽  
Long Bone ◽  
Third Harmonic ◽  
Acoustic Nonlinearity ◽  
The Third ◽  
Nonlinear Approach ◽  
Radial Depth

This article proposes an acoustic nonlinear approach combined with the time reversal technique to image cracks in long bones. In this method, the scattered ultrasound generated from the crack is recorded, and the third harmonic nonlinear component of the ultrasonic signal is used to reconstruct an image of the crack by the time reversal process. Numerical simulations are performed to examine the validity of this approach. The fatigue long bone is modeled as a hollow cylinder with a crack of 1, 0.1, and 0.225 mm in axial, radial and circumferential directions respectively. A broadband 500 kHz ultrasonic signal is used as the exciting signal, and the extended three-dimensional Preisach-Mayergoyz model is used to describe the nonclassical nonlinear dynamics of the crack. Time reversal is carried out by using the filtered third harmonic component. The localization capability depends on the radial depth of the crack.

THE INFLUENCE OF A CRITICAL ANGLE ON AN ORIENTATION OF RADIATION OF A SHEAR WAVE THE ANGLE BEAM PROBE

2019 ◽  
pp. 14-25
Author(s):  
V. N. Danilov
Keyword(s):  
Shear Wave ◽  
Critical Angle ◽  
Asymptotic Expression ◽  
Shear Waves ◽  
Far Field ◽  
Directivity Characteristic ◽  
The Third ◽  
Working Frequency

In a far field it is received asymptotic expression of displacement of the shear waves transmitted in the elastic environment by the angle beam probe in view of features of radiation of such waves under a angle of probe, coming nearer to the third critical. At sufficient remoteness from a critical corner this expression passes in received earlier in geometroacustical approximation. The estimations carried out for steel have shown, that for converters with nominal angles of probe 37 – 40 influence of this critical angle causes increase of an angle of registration of a maximum of the signal, observed earlier experimentally. This feature is influenced as distance up to points of registration of a shear wave, and with working frequency of the angle beam probe and its size piezoplate (width of the directivity characteristic).

scholarly journals On Terminological Peculiarities Of Designation Of Ultrasonic Waves Formed At The First Critical Angle

2018 ◽  
Vol 2018 (3) ◽  
pp. 14-26
Author(s):  
E.A. Davydov ◽  
◽  
V.P. Dyadin ◽  
A.L. Shekero ◽  
◽  
...  
Keyword(s):  
Critical Angle ◽  
Ultrasonic Waves

scholarly journals Flaw Detection in Highly Scattering Materials Using a Simple Ultrasonic Sensor Employing Adaptive Template Matching

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 268
Author(s):  
Biao Wu ◽  
Yong Huang
Keyword(s):  
Template Matching ◽  
Rayleigh Scattering ◽  
Flaw Detection ◽  
Ultrasonic Signal ◽  
Ultrasonic Sensor ◽  
Polycrystalline Materials ◽  
Spectral Difference ◽  
Time Frequency ◽  
Frequency Features ◽  
Spectrum Model

Ultrasonic sensors have been extensively used in the nondestructive testing of materials for flaw detection. For polycrystalline materials, however, due to the scattering nature of the material, which results in strong grain noise and attenuation of the ultrasonic signal, accurate detection of flaws is particularly difficult. In this paper, a novel flaw-detection method using a simple ultrasonic sensor is proposed by exploiting time-frequency features of an ultrasonic signal. Since grain scattering mostly happens in the Rayleigh scattering region, it is possible to separate grain-scattered noise from flaw echoes in the frequency domain employing their spectral difference. We start with the spectral modeling of grain noise and flaw echo, and how the two spectra evolve with time is established. Then, a time-adaptive spectrum model for flaw echo is proposed, which serves as a template for the flaw-detection procedure. Next, a specially designed similarity measure is proposed, based on which the similarity between the template spectrum and the spectrum of the signal at each time point is evaluated sequentially, producing a series of matching coefficients termed moving window spectrum similarity (MWSS). The time-delay information of flaws is directly indicated by the peaks of MWSSs. Finally, the performance of the proposed method is validated by both simulated and experimental signals, showing satisfactory accuracy and efficiency.

scholarly journals Non-destructive Testing of Wooden Elements

2021 ◽  
Vol 1203 (3) ◽  
pp. 032058
Author(s):  
Monika Zielińska ◽  
Magdalena Rucka
Keyword(s):  
Surface Defects ◽  
Test Methods ◽  
Ultrasonic Tomography ◽  
Test Results ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Near Surface ◽  
Thermal Techniques ◽  
Ground Penetrating ◽  
Non Destructive

Abstract Examining the condition of wooden elements is crucial from the perspective of proper structure performance. If the deterioration in the internal wood condition, which displays no symptoms visible from the outside, is detected, the further spread of the deterioration can be prevented. Test results often point to the necessity of conducting repairs and, renovations, replacing the structure of wooden beams, or even substituting a significant part of the structure. To achieve acceptable results, test methods should take into account the anisotropic nature of wood, which includes the shape of annual rings, as well as the location of the core in crosssection. To adopt methods based on physical effects, profound knowledge of wood physics is needed, particularly of interdependence. Apart from simple tests such as a visual inspection or tapping that are used to determine near-surface defects, non-destructive testing (NDT) plays an important role in the process. This paper presents the methods of non-destructive testing of wooden elements. These methods include tests conducted with ground penetrating radar (GPR), thermal techniques, microwaves, acoustic emission, ultrasonic tomography, and X-ray tomography. The paper summarises the use of non-destructive methods, indicating their advantages, disadvantages as well as some limitations.

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