The excitation of Lamb waves in pipes using dry-coupled piezoelectric transducers
01 Mar 1996-Journal of Nondestructive Evaluation (Kluwer Academic Publishers-Plenum Publishers)-Vol. 15, Iss: 1, pp 11-20
TL;DR: In this article, the development of a dry-coupled piezoelectric transducer system for the detection of corrosion in chemical plant pipework using cylindrical Lamb waves is described.
Abstract: The development of a dry-coupled piezoelectric transducer system for the detection of corrosion in chemical plant pipework using cylindrical Lamb waves is described. It is shown that the axisymmetricL(0,2) mode at a frequency of about 70 kHz is an attractive mode to use for longdistance propagation. The results show that a ring of piezoelectric length-expander elements can be used to excite theL(0,2) mode and to suppress all the nonaxisymmetric modes. Tests have been carried out both with the piezoelectric elements bonded to the pipe and fabricated into a simple transducer which was clamped against the pipe. The performance of the dry-coupled system was very similar to that of the bonded elements. In pulse echo tests, the noise floor obtained with the dry-coupled system was less than 1% of the amplitude of the propagatingL(0,2) mode. The drycoupled transducers provide a simple, light, readily detachable system for the long-range inspection of pipework.
Citations
More filters
TL;DR: In this paper, the authors provide a state-of-the-art review of guided wave based structural health monitoring (SHM) and highlight the future directions and open areas of research in guided wave-based SHM.
Abstract: The paper provides a state of the art review of guided wave based structural health monitoring (SHM). First, the fundamental concepts of guided wave propagation and its implementation for SHM is explained. Following sections present the different modeling schemes adopted, developments in the area of transducers for generation, and sensing of wave, signal processing and imaging technique, statistical and machine learning schemes for feature extraction. Next, a section is presented on the recent advancements in nonlinear guided wave for SHM. This is followed by section on Rayleigh and SH waves. Next is a section on real-life implementation of guided wave for industrial problems. The paper, though briefly talks about the early development for completeness,. is primarily focussed on the recent progress made in the last decade. The paper ends by discussing and highlighting the future directions and open areas of research in guided wave based SHM.
664 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
TL;DR: In this paper, the authors present a review of the studies of the propagation of the waves and their sensitivity to defects which have been conducted in order to provide a sound scientific basis for the method.
581 citations
TL;DR: In this article, the reflection of the L(0, 2), axially symmetric guidea elastic wave from notches in pipes is examined, using laboratory experiments and finite element simulation.
Abstract: The reflection of the L(0, 2), axially symmetric guidea elastic wave from notches in pipes is examined, using laboratory experiments and finite element simulation The result show that the reflection coefficient of this mode is very close to a linear function of the circumferential extent of the notch, and is a stronger function of the through thickne depth of the notch. The motivation for the work was the development of a technique for inspecting chemical plant pipework, but the study addresses the nature of the reflection function and has general applicability.
292 citations
TL;DR: Lamb waves propagate many metres along plate and shell structures, and so have great potential in "smart structure" applications where it is important for a transducer to interrogate a signific...
Abstract: Lamb waves can propagate many metres along plate and shell structures, and so have great potential in ‘smart structure’ applications where it is important for a transducer to interrogate a signific...
265 citations
References
More filters
Book•
01 Jan 1975
TL;DR: In this article, a comprehensive study of elastic wave propagation in solids is presented, ranging from the theory of waves and vibrations in strings to the three-dimensional theory of elastic waves in thick plates.
Abstract: The book presents a comprehensive study of elastic wave propagation in solids. Topics covered range from the theory of waves and vibrations in strings to the three-dimensional theory of waves in thick plates. The subject is covered in the following chapters: (1) waves and vibrations in strings, (2) longitudinal waves in thin rods, (3) flexural waves in thin rods, (4) waves in membranes, thin plates and shells, (5) waves in infinite media, (6) waves in semi-infinite media, (7) scattering and diffraction of elastic waves, and (8) wave propagation in plates and rods. Appendices contain introductory information on elasticity, transforms and experimental techniques. /TRRL/
3,359 citations
TL;DR: This paper presents a review of the main developments of the matrix techniques, and their use in response and modal models, with emphasis on ultrasonics applications.
Abstract: Research into ultrasonic NDE techniques for the inspection of multilayered structures relies strongly on the use of modeling tools which calculate dispersion curves and reflection and transmission spectra. These predictions are essential to enable the best inspection strategies to be identified and their sensitivities to be evaluated. General purpose multilayer modeling tools may be developed from a number of matrix formulations which have evolved in the latter half of this century and there is now a formidable number of publications on the subject. This paper presents a review of the main developments of the matrix techniques, and their use in response and modal models, with emphasis on ultrasonics applications. >
931 citations
"The excitation of Lamb waves in pip..." refers methods in this paper
...(22~ This matrix was implemented into a program developed by Lowe ( 23 ) at Imperial College, which solves the matrix (or coupled matrices if the pipe is multilayered) as a function of frequency and phase velocity....
[...]
TL;DR: In this paper, the propagation of free harmonic waves along a hollow circular cylinder of infinite extent is discussed within the framework of the linear theory of elasticity, and a characteristic equation appropriate to the circular hollow cylinder is obtained by use of the Helmholtz potentials for arbitrary values of the physical parameters involved.
Abstract: The propagation of free harmonic waves along a hollow circular cylinder of infinite extent is discussed within the framework of the linear theory of elasticity. A characteristic equation appropriate to the circular hollow cylinder is obtained by use of the Helmholtz potentials for arbitrary values of the physical parameters involved. Axially symmetric waves, the limiting modes of infinite wavelength, and a special family of equivoluminal modes are derived and discussed as degenerate cases of the general equations.
702 citations
TL;DR: In this article, the authors discuss the selection of the appropriate mode and frequency range for different inspection requirements and review the possible methods of excitation, response measurement and signal processing, and show that the presence of defects can be detected reliably from changes in the shape of the received waveform.
Abstract: Lamb waves can propagate over long distances which means that they are attractive for the quick, long range inspection of large structures, and they can also be useful for localized inspection, particularly in thin structures. This paper discusses the selection of the appropriate mode and frequency range for different inspection requirements and reviews the possible methods of excitation, response measurement and signal processing. It is usually desirable to transmit a single, non-dispersive mode, and excitation methods to achieve this are discussed. A variety of signal processing techniques from simple time domain to relatively complex two-dimensional Fourier analysis are available. Time domain processing can often be applied satisfactorily in low frequency-thickness regions where only two modes can propagate, but tends to be unreliable above the cut-off frequency of the a 1 mode. As an example of the design of a Lamb wave testing regime, a set of tests on a butt-welded steel plate with simulated weld defects of different depths is described. It is shown that by operating below the a 1 cut-off frequency with judicious selection of testing technique, the presence of defects can be detected reliably from changes in the shape of the received waveform.
371 citations
"The excitation of Lamb waves in pip..." refers methods in this paper
...Techniques for overcoming these problems when using Lamb waves in plates have been developed by Alleyne and Cawley.( 19 ,20)...
[...]
TL;DR: In this article, it is shown that the L(0, 1) mode, which is comparable to the A0 Lamb wave mode in flat plate, can be generated with acceptable efficiency.
309 citations
"The excitation of Lamb waves in pip..." refers background in this paper
...Lamb waves; see for example, Silk and Bainton ( 1 )) and...
[...]