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Special Issue "Advances in Ultrasonic Guided Wave Sensor Technologies for Structural Health Monitoring"

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (20 July 2020).

Special Issue Editors

Prof. Dr. Tat-Hean Gan
Website
Guest Editor
Brunel University London, Brunel Innovation Centre, Uxbridge, UK
Interests: ultrasonic guided waves; non-destructive testing; artificial intelligence; non-contact ultrasonics; Industry 4.0; signal processing; sensors; instrumentations
Special Issues and Collections in MDPI journals
Dr. Shehan Lowe
Website
Guest Editor
Nuclear Advanced Manufacturing Research Centre (Nuclear AMRC), S60 5WG Rotherham, UK
Interests: ultrasonic guided waves; non-destructive testing; acoustics; sensor development; numerical modelling; signal processing
Prof. Dr. Wamadeva Balachandran
Website
Guest Editor
Department of Systems Engineering, Brunel University London, Brunel Innovation Centre, Uxbridge, UK
Interests: guided wave measurement; electromagnetic acoustic transducers; Lab-on-a-chip; electromagnetic field sensing; global positioning satellite system and MEMS
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Ultrasonic Guided Wave (UGW) testing has gained greater attention from the industry for its inherent capability of long-range inspection. This technology is widely used as a screening tool in many industries, e.g., oil and gas, renewable energy, naval, construction, and aerospace. Recent attempts have been made to improve the resolution and sensitivity of UGW sensors for quantitative measurements of structural health and also to inspect complex structures, e.g., glass laminate aluminium reinforced epoxy, and carbon fiber reinforced polymer.  
This Special Issue is aimed to the submission of both review and original research articles related to the advancement of UGW sensor development, signal processing, and applications of UGW for structural assessment. Topics include but are not limited to the following:

  • Non-destructive testing and material characterisation
  • The inspection of complex material and structures using UGW
  • Flexible sensor development
  • UGW imaging and visualisation
  • Industrial applications
  • The remote monitoring of structural health

Prof. Dr. Tat-Hean Gan
Dr. Shehan Lowe
Prof. Dr. Wamadeva Balachandran
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Ultrasonic guided wave
  • Acoustic sensing
  • Sensor development
  • Signal processing
  • Numerical modelling
  • Non-destructive testing
  • Imaging
  • Composite inspection
  • Material characterization
  • Automation

Published Papers (10 papers)

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Research

Open AccessArticle
Ultrasonic Guided Wave Testing on Cross-Ply Composite Laminate: An Empirical Study
Sensors 2020, 20(18), 5291; https://doi.org/10.3390/s20185291 - 16 Sep 2020
Abstract
Structural health monitoring comprises a set of techniques to detect defects appearing in structures. One of the most viable techniques is based on the guided ultrasonic wave test (UGWT), which consists of emitting waves throughout the structure, acquiring the emitted waves with various [...] Read more.
Structural health monitoring comprises a set of techniques to detect defects appearing in structures. One of the most viable techniques is based on the guided ultrasonic wave test (UGWT), which consists of emitting waves throughout the structure, acquiring the emitted waves with various sensors, and processing the waves to detect changes in the structure. The UGWT of layered composite structures is challenging due to the anisotropic wave propagation characteristics of such structures and to the high signal attenuation that the waves experience. Hence, very low amplitude signals that are hard to distinguish from noise are typically recovered. This paper analyzes the propagation of guided waves along a cross-ply composite laminate following an empirical methodology. The research compares several implementations for UGWT with piezoelectric wafer active sensors. The reference for comparison is set on a basic mode, which considers the application of nominal voltage to a single sensor. The attenuation and spreading of the waves in several directions are compared when more energy is applied to the monitored structure. In addition, delayed multiple emission is also considered in multisensor tests. The goal of all the UGWT configurations is to transmit more energy to the structure such that the echoes of the emission are of greater amplitude and they ease the signal processing. The study is focused on the realization of viable monitoring systems for aeronautical composite made structures. Full article
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Open AccessArticle
Improved Defect Detection of Guided Wave Testing Using Split-Spectrum Processing
Sensors 2020, 20(17), 4759; https://doi.org/10.3390/s20174759 - 23 Aug 2020
Abstract
Ultrasonic guided wave (UGW) testing is widely applied in numerous industry areas for the examination of pipelines where structural integrity is of concern. Guided wave testing is capable of inspecting long lengths of pipes from a single tool location using some arrays of [...] Read more.
Ultrasonic guided wave (UGW) testing is widely applied in numerous industry areas for the examination of pipelines where structural integrity is of concern. Guided wave testing is capable of inspecting long lengths of pipes from a single tool location using some arrays of transducers positioned around the pipe. Due to dispersive propagation and the multimodal behavior of UGW, the received signal is usually degraded and noisy, that reduce the inspection range and sensitivity to small defects. Therefore, signal interpretation and identifying small defects is a challenging task in such systems, particularly for buried/coated pipes, in that the attenuation rates are considerably higher compared with a bare pipe. In this work, a novel solution is proposed to address this issue by employing an advanced signal processing approach called “split-spectrum processing” (SSP) to minimize the level of background noise and enhance the signal quality. The SSP technique has already shown promising results in a limited trial for a bar pipe and, in this work, the proposed technique has been experimentally compared with the traditional approach for coated pipes. The results illustrate that the proposed technique significantly increases the signal-to-noise ratio and enhances the sensitivity to small defects that are hidden below the background noise. Full article
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Open AccessArticle
Selective Generation of Lamb Wave Modes in a Finite-Width Plate by Angle-Beam Excitation Method
Sensors 2020, 20(14), 3868; https://doi.org/10.3390/s20143868 - 10 Jul 2020
Abstract
A Lamb wave in a plate with a finite width has both thickness and width modes, whereas only thickness modes exist in an infinitely wide plate. The thickness and width modes are numerously formed in a finite-width plate, and they all have different [...] Read more.
A Lamb wave in a plate with a finite width has both thickness and width modes, whereas only thickness modes exist in an infinitely wide plate. The thickness and width modes are numerously formed in a finite-width plate, and they all have different cut-off frequencies, wave velocities, and wave structures. These different characteristics can be utilized in various applications, but a selective generation method for a particular Lamb wave mode in a finite-width plate has not been sufficiently studied, and only a method using multiple elements has been reported. This paper presents the selective generation of a certain Lamb wave mode in a finite-width plate by an angle-beam excitation method using single or dual wedges. In the proposed generation method, a specially designed wedge with grooves or a patch having insulation layers is employed for partial acoustic insulation of the ultrasonic energy incident into the plate. The feasibility of the proposed method was investigated through finite element method (FEM) simulations for Lamb wave excitation and propagation, and then experimentally demonstrated by the measurement of Lamb wave propagation using a laser scanning vibrometer. Full article
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Open AccessArticle
An Empirical Study on Transmission Beamforming for Ultrasonic Guided-Wave Based Structural Health Monitoring
Sensors 2020, 20(5), 1445; https://doi.org/10.3390/s20051445 - 06 Mar 2020
Cited by 1
Abstract
The development of reliable structural health monitoring techniques is enabling a healthy transition from preventive to condition-based maintenance, hence leading to safer and more efficient operation of different industries. Ultrasonic guided-wave based beamforming is one of the most promising techniques, which supports the [...] Read more.
The development of reliable structural health monitoring techniques is enabling a healthy transition from preventive to condition-based maintenance, hence leading to safer and more efficient operation of different industries. Ultrasonic guided-wave based beamforming is one of the most promising techniques, which supports the monitoring of large thin-walled structures. However, beamforming has been typically applied to the post-processing stage (also known as virtual or receiver beamforming) because transmission or physical beamforming requires complex hardware configurations. This paper introduces an electronic structural health monitoring system that carries out transmission beamforming experiments by simultaneously emitting and receiving ultrasonic guided-waves using several transducers. An empirical characterization of the transmission beamforming technique for monitoring an aluminum plate is provided in this work. The high signal-to-noise ratio and accurate angular precision of the physical signal obtained in the experiments suggest that transmission beamforming can increase the reliability and robustnessof this monitoring technique for large structures and in real-world noisy environments. Full article
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Open AccessArticle
Acoustic Inspection of Concrete Structures Using Active Weak Supervision and Visual Information
Sensors 2020, 20(3), 629; https://doi.org/10.3390/s20030629 - 23 Jan 2020
Abstract
Concrete structures are featured heavily in most modern societies. In recent years, the need to inspect those structures has been a growing concern and the automation of inspection methods is highly demanded. Acoustic methods such as the hammering test are one of the [...] Read more.
Concrete structures are featured heavily in most modern societies. In recent years, the need to inspect those structures has been a growing concern and the automation of inspection methods is highly demanded. Acoustic methods such as the hammering test are one of the most popular non-destructive testing methods for this task. In this paper, an approach to defect detection in concrete structures with active weak supervision and visual information is proposed. Based on audio and position information, pairs of samples are actively queried to a user on their similarity. Those are used to transform the feature space into a favorable one, in a weakly supervised fashion, for clustering defect and non-defect samples, reinforced by position information. Experiments conducted in both laboratory conditions and in field conditions proved the effectiveness of the proposed method. Full article
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Open AccessArticle
Piezoelectric Transducers for Structural Health Monitoring of Joint Structures in Cylinders: A Wave-Based Design Approach
Sensors 2020, 20(3), 601; https://doi.org/10.3390/s20030601 - 21 Jan 2020
Abstract
Joint structures, such as riveting, hinges, and flanges, are widely used in complex mechanical systems. A small unexpected change of a joint can lead to complicated wave-scattering in its connected waveguides. The conversion between wave modes can be used to quantify the variation [...] Read more.
Joint structures, such as riveting, hinges, and flanges, are widely used in complex mechanical systems. A small unexpected change of a joint can lead to complicated wave-scattering in its connected waveguides. The conversion between wave modes can be used to quantify the variation of the connection status of joints. This gives rise to the challenge of exciting and sensing only one specific wave mode in practice. In this paper, transmitted wave amplitudes of a flange joint are first calculated by the wave finite element method (WFEM) to study the quantitative relationship between the local stiffness changes of the damaged site and the wave-mode conversion. Wave-mode piezoelectric transducers are subsequently designed for torsional, longitudinal, and flexural waves in cylindrical waveguides. The idea is to use the distribution and interconnection of the piezoelectric materials to cancel the charge contributed from the non-targeting waves. We conducted numerical simulations to demonstrate the selective coupling features of the designed wave transducers and found difference of several orders of magnitude in voltages between targeting wave mode and other wave modes. Four selected wave transducers were then extended to monitor the connection status of the flange. The wave-scattering features in the simulation and WFEM were verified to be in good agreement. Full article
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Open AccessArticle
Debonding Size Estimation in Reinforced Concrete Beams Using Guided Wave-Based Method
Sensors 2020, 20(2), 389; https://doi.org/10.3390/s20020389 - 10 Jan 2020
Cited by 1
Abstract
The following paper presents the results of the theoretical and experimental analysis of the influence of debonding size on guided wave propagation in reinforced concrete beams. The main aim of the paper is a development of a novel, baseline-free method for determining the [...] Read more.
The following paper presents the results of the theoretical and experimental analysis of the influence of debonding size on guided wave propagation in reinforced concrete beams. The main aim of the paper is a development of a novel, baseline-free method for determining the total area of debonding between steel rebar embedded in a concrete cover on the basis of the average wave velocity or the time of flight. The correctness of the developed relationships was verified during the experimental tests, which included propagation of guided waves in concrete beams with the varying debonding size, shape and location. The analysis of the collected results proved that guided waves can be efficiently used not only in the debonding detection, but also in an exact determining of its total area, which is extremely important in the context of the nondestructive assessment of the load capacity of the reinforced concrete structures. The undeniable advantage of the proposed method is that there are no requirements for any baseline signals collected for an undamaged structure. The paper comprises of the detailed step by step algorithm description and a discussion of both the advantages and disadvantages. Full article
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Open AccessArticle
Experimental Study on Active Interface Debonding Detection for Rectangular Concrete-Filled Steel Tubes with Surface Wave Measurement
Sensors 2019, 19(15), 3248; https://doi.org/10.3390/s19153248 - 24 Jul 2019
Cited by 3
Abstract
Concrete-filled steel tube (CFST) members have been widely employed as major structural members carrying axial or vertical loads and the interface bond condition between steel tube and concrete core plays key roles in ensuring the confinement effect of steel tube on concrete core. [...] Read more.
Concrete-filled steel tube (CFST) members have been widely employed as major structural members carrying axial or vertical loads and the interface bond condition between steel tube and concrete core plays key roles in ensuring the confinement effect of steel tube on concrete core. An effective interface debonding defect detection approach for CFSTs is critical. In this paper, an active interface debonding detection approach using surface wave measurement with a piezoelectric lead zirconate titanate (PZT) patch as sensor mounted on the outer surface of the CFST member excited with a PZT actuator mounted on the identical surface is proposed in order to avoid embedding PZT-based smart aggregates (SAs) in concrete core. In order to validate the feasibility of the proposed approach and to investigate the effect of interface debonding defect on the surface wave measurement, two rectangular CFST specimens with different degrees of interface debonding defects on three internal surfaces are designed and experimentally studied. Surface stress waves excited by the PZT actuator and propagating along the steel tube of the specimens are measured by the PZT sensors with a pitch and catch pattern. Results show that the surface-mounted PZT sensor measurement is sensitive to the existence of interface debonding defect and the interface debonding defect leads to the increase in the voltage amplitude of surface wave measurement. A damage index defined with the surface wave measurement has a linear relationship with the heights of the interface debonding defects. Full article
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Open AccessArticle
Improved SH0 Guided Wave Transducers Based on Piezoelectric Fiber Patches
Sensors 2019, 19(13), 2990; https://doi.org/10.3390/s19132990 - 06 Jul 2019
Cited by 4
Abstract
A piezoelectric fiber patch (PFP) is a transducer type that is suitable for guided-wave-based structural health monitoring (SHM) due to its light, thin, and flexible characteristics. In our previous work, a PFP-based transducer design for selective excitation of the zero-order shear horizontal wave [...] Read more.
A piezoelectric fiber patch (PFP) is a transducer type that is suitable for guided-wave-based structural health monitoring (SHM) due to its light, thin, and flexible characteristics. In our previous work, a PFP-based transducer design for selective excitation of the zero-order shear horizontal wave mode (SH0) was introduced (shear horizontal PFP (SHPFP)). In this work, two modified SH0 wave PFP transducer designs are proposed: the rounded corner design and the dual design. The degree of improvement is determined by a numerical simulation and the dual design—the design with the most promise—is experimentally realized. Laser Vibrometry measured the generated wave field, confirming the results from the simulation. The new designs can generate an almost pure SH0 wave. The dual design has a very strong directivity that is useful for several guided-wave-based SHM applications. The conclusions on the design’s properties as a transmitter are also valid for its properties as a sensor due to the reciprocity of piezoelectric transducers. Full article
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Open AccessArticle
Characterization and Design Improvement of a Thickness-Shear Lead Zirconate Titanate Transducer for Low Frequency Ultrasonic Guided Wave Applications
Sensors 2019, 19(8), 1848; https://doi.org/10.3390/s19081848 - 18 Apr 2019
Cited by 1
Abstract
Thickness-shear transducers for guided wave testing have been used in industry for over two decades and much research has been conducted to improve the resolution and sensitivity. Due to a geometric feature of the current state-of-the art transducer, there is an out-of-plane component [...] Read more.
Thickness-shear transducers for guided wave testing have been used in industry for over two decades and much research has been conducted to improve the resolution and sensitivity. Due to a geometric feature of the current state-of-the art transducer, there is an out-of-plane component in the propagation direction of the fundamental shear horizontal mode which complicates the signal interpretation. In such case, complex signal processing techniques need to be used for mode discrimination to assess the structural health with higher precision. Therefore, it is important to revise the transducer design to eliminate the out-of-plane components in the propagation direction of fundamental shear horizontal mode. This will enhance the mode purity of fundamental shear horizontal mode for its application in guided wave inspection. A numerical investigation has been conducted on a 3 mm thick 2 m circular steel plate to understand the behaviour and the characteristics of the state-of-the-art thickness-shear transducer. Based on the results, it is noted that the redesigning the electrode arrangement will suppress the out-of-plane components on the propagation direction of the fundamental shear horizontal mode. With the aid of this information current state-of-the-art transducers were redesigned and tested in laboratory conditions using the 3D Laser Doppler Vibrometer. This information will aid future transducer designers improve the resolution of thickness-shear transducers for guided wave applications and reduce the weight and cost of transducer array by eliminating the need of additional transducers to suppress spurious modes. Full article
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