Time-frequency characteristics of longitudinal modes in symmetric mode conversion for defect characterization in guided waves-based pipeline inspection
TL;DR: In this paper, the authors focused on the interconversion process of axisymmetric modes for incident longitudinal modes when interacting with the defects in pipeline whist ignoring the converted non-axisymmetric modes through suppressing them in reception.
Abstract: The converted modes generated by mode conversion in guided waves-based inspection can provide plenty of defect information, and the reasonable usage of multiple wave modes can improve the results of defect inspection and evaluation. Axisymmetric longitudinal L(0,2) mode guided-waves is widely used in pipeline inspection currently, and the lower order longitudinal L(0,1) mode is easily excited simultaneously. This paper focuses the interconversion process of axisymmetric modes for incident longitudinal modes when interacting with the defects in pipeline whist ignoring the converted non-axisymmetric modes through suppressing them in reception. This process is defined as symmetric mode conversion in this research. The pattern of axisymmetric mode sequence during symmetric mode conversion is identified and the method is proposed to extract the converted axisymmetric mode components for analysis. The relationships between the defect features and the modes generated in symmetric mode conversion under the excitation of longitudinal mode waves are investigated. The conclusion obtained by numerical simulation is also experimentally verified using guided wave data from practical pipeline. The results show that longitudinal modes in symmetric mode conversion present the useful time and frequency characteristics, which provides the potential for establishing an effective defect inspection and evaluation method with longitudinal guided waves.
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TL;DR: In this paper , the authors proposed a framework of machine learning in the field of oil and gas pipeline corrosion prediction, and the necessity of data preprocessing and feature correlation analysis are indicated.
1 citations
TL;DR: In this article , a wideband dispersion reversal (WDR) method optimized tomography is developed for robust localization of defects using ultrasonic Lamb waves, where predispersive wideband excitations of a certain Lamb wave mode are generated based on the configuration of transducers, and reconstruction independent component analysis is used for wave mode separation.
1 citations
TL;DR: In this paper , an ultrasonic guided wave pipe crack grade identification model based on improved one-dimensional convolutional neural network is proposed, in which the multi-size convolutions are used to replace the traditional single-size kernels.
TL;DR: In this article , the influence of complexity on the propagation characteristics of ultrasonic waves in pipeline network is investigated by numerical simulation of different pipeline configurations, and the sensitive features were selected from results obtained by parametric study.
Abstract: Currently, with the advancement of the urbanization, the pipeline explosions may lead to a very large catastrophe in the city. Pipeline networks are regularly inspected using nondestructive evaluation (NDE) methods such as smart pigs (cylinder-shaped electronic devices to detect metal loses), mapping tools based on GPS for above ground pipelines, guided wave ultrasonics and hydrostatic testing. The major challenge for inspecting pipeline networks occurs for unknown map of distribution, where geometric and spatial features may not be known, and the properties of pipe structure make pigging impossible. Therefore, this research proposed to identify the geometric and spatial signatures in the pipeline networks in urban settings by means of elastic wave propagation. Firstly, the geometric and spatial complexity was defined by extracting the features from the pipeline network, which includes thickness of wall, diameters, types of connections, path, materials and so on. Secondly, the influence of complexity on the propagation characteristics of ultrasonic waves in pipeline network is investigated by numerical simulation of different pipeline configurations. Then the sensitive features were selected from results obtained by parametric study. Therefore, the geometric distribution of improperly documented pipeline networks can be identified and then their structural state is assessed accordingly.
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01 Sep 2004
TL;DR: In this article, the theory of elasticity was introduced and basic formulas and concepts in complex variables in the theory and application of wave propagation were discussed. But the authors did not consider the effects of wave scattering on the wave propagation experiments.
Abstract: Preface 1. Introduction 2. Dispersion principles 3. Unbounded isotropic and anisotropic media 4. Reflection and refraction 5. Oblique incidence 6. Wave scattering 7. Surface and subsurface waves 8. Waves in plates 9. Interface waves 10. Layer on a half space 11. Waves in rods 12. Waves in hollow cylinders 13. Guided waves in multiple layers 14. Source influence 15. Horizontal shear 16. Waves in an anisotropic layer 17. Elastic constant determination 18. Waves in viscoelastic media 19. Stress influence 20. Boundary element methods Bibliography Appendices A. Ultrasonic nondestructive testing principles, analysis and display technology B. Basic formulas and concepts in the theory of elasticity C. Basic formulas in complex variables D. Schlieren imaging and dynamic photoelasticity E. Key wave propagation experiments Index.
2,570 citations
TL;DR: This paper begins with an overview of damage prognosis, and a description of the basic methodology of guided-wave SHM, then reviews developments from the open literature in various aspects of this truly multidisciplinary field.
Abstract: In this paper we present the state of the art in the field of guided-wave structural health monitoring (SHM). We begin with an overview of damage prognosis, and a description of the basic methodology of guided-wave SHM. We then review developments from the open literature in various aspects of this truly multidisciplinary field. First, we discuss different transducer technologies, including both piezoelectric and non-conventional popular and non-conventional piezoelectric transducers. Next, we examine guided-wave theory, tracing its early history down to modern developments. Following this, we detail the efforts into models for guided-wave excitation by SHM transducers. Then, we review several signal processing related works. The next topic in Section 6 is guided-wave SHM system development, and we explore various packaging ideas, integrated solutions and efforts to examine robustness to different service conditions. We also highlight the broad spectrum of applications in which this technology has been tested. We then present some investigations that have attempted to combine guided-wave approaches with other complementary SHM technologies for better system performance. Finally, we propose desirable developments for further advancement of this field.
988 citations
TL;DR: The results indicate that Lamb waves may be used to find notches when the wavelength to notch depth ratio is on the order of 40, and the 2-D Fourier transform method is used to quantify Lamb wave interactions with defects.
Abstract: The interaction of individual Lamb waves with a variety of defects simulated by notches is investigated using finite-element analysis, and the results are checked experimentally. Excellent agreement is obtained. It is shown that a 2-D Fourier transform method may be used to quantify Lamb wave interactions with defects. The sensitivity of individual Lamb waves to particular notches is dependent on the frequency-thickness product, the mode type and order, and the geometry of the notch. The sensitivity of the Lamb modes a/sub 1/, alpha /sub 0/, and s/sub 0/ to simulated defects in different frequency-thickness regions is predicted as a function of the defect depth to plate thickness ratio and the results indicate that Lamb waves may be used to find notches when the wavelength to notch depth ratio is on the order of 40. Transmission ratios of Lamb waves across defects are highly frequency dependent. >
912 citations
TL;DR: In this article, a two-dimensional Fourier transform (2D FFT) was used to measure the amplitudes and velocities of the Lamb waves propagating in a plate, the output of the transform being presented using an isometric projection which gives a three-dimensional view of the wave-number dispersion curves.
Abstract: A technique for the analysis of propagating multimode signals is presented. The method involves a two-dimensional Fourier transformation of the time history of the waves received at a series of equally spaced positions along the propagation path. The technique has been used to measure the amplitudes and velocities of the Lamb waves propagating in a plate, the output of the transform being presented using an isometric projection which gives a three-dimensional view of the wave-number dispersion curves. The results of numerical and experimental studies to measure the dispersion curves of Lamb waves propagating in 0.5-, 2.0-, and 3.0-mm-thick steel plates are presented. The results are in good agreement with analytical predictions and show the effectiveness of using the two-dimensional Fourier transform (2-D FFT) method to identify and measure the amplitudes of individual Lamb modes.
889 citations
TL;DR: In this article, the authors provide a vision of ultrasonic guided wave inspection potential as we move forward into the new millennium and provide a brief description of the sensor and software technology that will make ultrasonic guidance wave inspection commonplace in the next century.
Abstract: Ultrasonic guided wave inspection is expanding rapidly to many different areas of manufacturing and in-service inspection. The purpose of this paper is to provide a vision of ultrasonic guided wave inspection potential aswe move forward into the new millennium. An increased understanding of the basic physics and wave mechanics associated with guided wave inspection has led to an increase in practical nondestructive evaluation and inspection problems. Some fundamental concepts and a number of different applications that are currently being considered will be presented in the paper along with a brief description of the sensor and software technology that will make ultrasonic guided wave inspection commonplace in the next century.
623 citations