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8 pages, 206 KiB

Open AccessEditorial

Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation

by Zenghua Liu

Sensors 2024, 24(2), 603; https://doi.org/10.3390/s24020603 - 17 Jan 2024

Cited by 4 | Viewed by 2216

Abstract

During manufacturing, processing, and usage, various types of damage may be caused in structures [...] Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

Research

Jump to: Editorial, Review

25 pages, 6742 KiB

Open AccessArticle

Sandwich Face Layer Debonding Detection and Size Estimation by Machine-Learning-Based Evaluation of Electromechanical Impedance Measurements

by Christoph Kralovec, Bernhard Lehner, Markus Kirchmayr and Martin Schagerl

Sensors 2023, 23(6), 2910; https://doi.org/10.3390/s23062910 - 7 Mar 2023

Cited by 2 | Viewed by 1965

Abstract

The present research proposes a two-step physics- and machine-learning(ML)-based electromechanical impedance (EMI) measurement data evaluation approach for sandwich face layer debonding detection and size estimation in structural health monitoring (SHM) applications. As a case example, a circular aluminum sandwich panel with idealized face [...] Read more.

The present research proposes a two-step physics- and machine-learning(ML)-based electromechanical impedance (EMI) measurement data evaluation approach for sandwich face layer debonding detection and size estimation in structural health monitoring (SHM) applications. As a case example, a circular aluminum sandwich panel with idealized face layer debonding was used. Both the sensor and debonding were located at the center of the sandwich. Synthetic EMI spectra were generated by a finite-element(FE)-based parameter study, and were used for feature engineering and ML model training and development. Calibration of the real-world EMI measurement data was shown to overcome the FE model simplifications, enabling their evaluation by the found synthetic data-based features and models. The data preprocessing and ML models were validated by unseen real-world EMI measurement data collected in a laboratory environment. The best detection and size estimation performances were found for a One-Class Support Vector Machine and a K-Nearest Neighbor model, respectively, which clearly showed reliable identification of relevant debonding sizes. Furthermore, the approach was shown to be robust against unknown artificial disturbances, and outperformed a previous method for debonding size estimation. The data and code used in this study are provided in their entirety, to enhance comprehensibility, and to encourage future research. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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17 pages, 5805 KiB

Open AccessArticle

A Novel Baseline-Free Method for Damage Localization Using Guided Waves Based on Hyperbola Imaging Algorithm

by Jichao Xu, Wujun Zhu, Xunlin Qiu and Yanxun Xiang

Sensors 2023, 23(4), 2050; https://doi.org/10.3390/s23042050 - 11 Feb 2023

Cited by 3 | Viewed by 1880

Abstract

Most imaging methods based on ultrasonic Lamb waves in structural health monitoring requires reference signals, recorded in the intact state. This paper focuses on a novel baseline-free method for damage localization using Lamb waves based on a hyperbolic algorithm. This method employs a [...] Read more.

Most imaging methods based on ultrasonic Lamb waves in structural health monitoring requires reference signals, recorded in the intact state. This paper focuses on a novel baseline-free method for damage localization using Lamb waves based on a hyperbolic algorithm. This method employs a special array with a relatively small number of transducers and only one branch of the hyperbola. The novel symmetrical array was arranged on plate structures to eliminate the direct waves. The time difference between the received signals at symmetrical sensors was obtained from the damage-scattered waves. The sequence of time difference for constructing the hyperbolic trajectory was calculated by the cross-correlation method. Numerical simulation and experimental measurements were implemented on an aluminum plate with a through-thickness hole in the current state. The imaging results show that both the damages outside and inside the diamond-shaped arrays can be localized, and the positioning error reaches the maximum for the diamond-shaped array with the minimum size. The results indicate that the position of the through-hole in the aluminum plate can be identified and localized by the proposed baseline-free method. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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16 pages, 7627 KiB

Open AccessArticle

Surface Monitoring of an MSW Landfill Based on Linear and Angular Measurements, TLS, and LIDAR UAV

by Grzegorz Pasternak, Janina Zaczek-Peplinska, Klaudia Pasternak, Jacek Jóźwiak, Mariusz Pasik, Eugeniusz Koda and Magdalena Daria Vaverková

Sensors 2023, 23(4), 1847; https://doi.org/10.3390/s23041847 - 7 Feb 2023

Cited by 11 | Viewed by 2507

Abstract

Surface monitoring of landfills is crucial not only during their operation but also for later land restoration and development. Measurements concern environmental factors, such as leachate, migration of pollutants to water, biogas, and atmospheric emissions, and geotechnical factors, such as stability and subsidence. [...] Read more.

Surface monitoring of landfills is crucial not only during their operation but also for later land restoration and development. Measurements concern environmental factors, such as leachate, migration of pollutants to water, biogas, and atmospheric emissions, and geotechnical factors, such as stability and subsidence. Landfill subsidence can be measured using modern surveying techniques. Modern measurement methods for landfill body displacement monitoring and their control after restoration and adaptation as recreational areas include terrestrial laser scanning (TLS), and scanning and low-altitude photogrammetric measurements from an unmanned aerial vehicle (UAV). The acquired measurement data in the form of 3D point clouds should be referenced to the local control network to enable a comprehensive analysis of data acquired using various techniques, including geotechnical sensors such as benchmarks, piezometers, and inclinometers. This study discusses the need for surface monitoring of municipal solid waste (MSW) landfills. A properly 3-D mapped landfill mass is the basis for ensuring the geotechnical safety of the restored landfill. Based on archival data and current measurements of the Radiowo landfill (Poland), this study compares the advantages and limitations of the following measurement techniques: linear and angular measurements, satellite measurements, TLS, and UAV scanning and photogrammetry, considering specific conditions of the location and vegetation of the landfill. Solutions for long-term monitoring were proposed, considering the cost and time resolution necessary for creating a differential model of landfill geometry changes. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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13 pages, 4813 KiB

Open AccessArticle

A Novel Adaptive Time-Frequency Filtering Approach to Enhance the Ultrasonic Inspection of Stainless Steel Structures

by Biao Wu, Haitao Yang, Yong Huang, Wensong Zhou and Xiaohui Liu

Sensors 2023, 23(2), 1030; https://doi.org/10.3390/s23021030 - 16 Jan 2023

Cited by 1 | Viewed by 2664

Abstract

Ultrasonic nondestructive testing (NDT) provides a valuable insight into the integrity of stainless steel structures, but the noise caused by the scattering of stainless steel microstructure often limits the effectiveness of inspection. This work presents a novel adaptive filtering approach to enhance the [...] Read more.

Ultrasonic nondestructive testing (NDT) provides a valuable insight into the integrity of stainless steel structures, but the noise caused by the scattering of stainless steel microstructure often limits the effectiveness of inspection. This work presents a novel adaptive filtering approach to enhance the signal-to-noise ratio (SNR) of a measured ultrasonic signal from the inspection of a stainless steel component, enabling the detection of hidden flaws under strong noise. After the spectral modeling of the noisy ultrasonic NDT signal, the difference between the spectral characteristics of a flaw echo and that of grain noise is highlighted, and a reference spectrum model to estimate the frequency spectrum of the echo reflected by any possible flaw is developed. Then, the signal is segmented and the similarity between the spectra of data segments and the reference spectra is evaluated quantitatively by the spectral similarity index (SSI). Based on this index, an adaptive time-frequency filtering scheme is proposed. Each data segment is processed by the filtering to suppress the energy of noise. The processed data segments are recombined to generate the de-noised signal after multiplying weighting coefficients, which again is determined by the SSI. The performance of the proposed method for SNR enhancement is evaluated by both the simulated and experimental signal and the effectiveness has been successfully demonstrated. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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22 pages, 2693 KiB

Open AccessArticle

Discussion on a Vehicle–Bridge Interaction System Identification in a Field Test

by Ryota Shin, Yukihiko Okada and Kyosuke Yamamoto

Sensors 2023, 23(1), 539; https://doi.org/10.3390/s23010539 - 3 Jan 2023

Cited by 3 | Viewed by 3384

Abstract

For infrastructures to be sustainable, it is essential to improve maintenance and management efficiency. Vibration-based monitoring methods are being investigated to improve the efficiency of infrastructure maintenance and management. In this paper, signals from acceleration sensors attached to vehicles traveling on bridges are [...] Read more.

For infrastructures to be sustainable, it is essential to improve maintenance and management efficiency. Vibration-based monitoring methods are being investigated to improve the efficiency of infrastructure maintenance and management. In this paper, signals from acceleration sensors attached to vehicles traveling on bridges are processed. Methods have been proposed to individually estimate the modal parameters of bridges and road unevenness from vehicle vibrations. This study proposes a method to simultaneously estimate the mechanical parameters of the vehicle, bridge, and road unevenness with only a few constraints. Numerical validation examined the effect of introducing the Kalman filter on the accuracy of estimating the mechanical parameters of vehicles and bridges. In field tests, vehicle vibration, bridge vibration, and road unevenness were measured and verified, respectively. The road surface irregularities estimated by the proposed method were compared with the measured values, which were somewhat smaller than the measured values. Future studies are needed to improve the efficiency of vehicle vibration preprocessing and optimization methods and to establish a methodology for evaluating accuracy. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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20 pages, 5691 KiB

Open AccessArticle

A Study on Structural Health Monitoring of a Large Space Antenna via Distributed Sensors and Deep Learning

by Federica Angeletti, Paolo Iannelli, Paolo Gasbarri, Massimo Panella and Antonello Rosato

Sensors 2023, 23(1), 368; https://doi.org/10.3390/s23010368 - 29 Dec 2022

Cited by 10 | Viewed by 2342

Abstract

Most modern Earth and Universe observation spacecraft are now equipped with large lightweight and flexible structures, such as antennas, telescopes, and extendable elements. The trend of hosting more complex and bigger appendages, essential for high-precision scientific applications, made orbiting satellites more susceptible to [...] Read more.

Most modern Earth and Universe observation spacecraft are now equipped with large lightweight and flexible structures, such as antennas, telescopes, and extendable elements. The trend of hosting more complex and bigger appendages, essential for high-precision scientific applications, made orbiting satellites more susceptible to performance loss or degradation due to structural damages. In this scenario, Structural Health Monitoring strategies can be used to evaluate the health status of satellite substructures. However, in particular when analysing large appendages, traditional approaches may not be sufficient to identify local damages, as they will generally induce less observable changes in the system dynamics yet cause a relevant loss of payload data and information. This paper proposes a deep neural network to detect failures and investigate sensor sensitivity to damage classification for an orbiting satellite hosting a distributed network of accelerometers on a large mesh reflector antenna. The sensors-acquired time series are generated by using a fully coupled 3D simulator of the in-orbit attitude behaviour of a flexible satellite, whose appendages are modelled by using finite element techniques. The machine learning architecture is then trained and tested by using the sensors’ responses gathered in a composite scenario, including not only the complete failure of a structural element (structural break) but also an intermediate level of structural damage. The proposed deep learning framework and sensors configuration proved to accurately detect failures in the most critical area or the structure while opening new investigation possibilities regarding geometrical properties and sensor distribution. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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22 pages, 25648 KiB

Open AccessArticle

Lock-In Thermal Test Simulation, Influence, and Optimum Cycle Period for Infrared Thermal Testing in Non-Destructive Testing

by António Ramos Silva, Mário Vaz, Sofia Leite and Joaquim Mendes

Sensors 2023, 23(1), 325; https://doi.org/10.3390/s23010325 - 28 Dec 2022

Cited by 3 | Viewed by 1990

Abstract

Lock-in thermal tests (LTTs) are one of the best ways to detect defects in composite materials. The parameter that most affects their performance is the cycle period of the stimulation wave. Its influence on the amplitude-phase results was determined by performing various numeric [...] Read more.

Lock-in thermal tests (LTTs) are one of the best ways to detect defects in composite materials. The parameter that most affects their performance is the cycle period of the stimulation wave. Its influence on the amplitude-phase results was determined by performing various numeric simulations and laboratory tests. The laboratory tests were used to infer part of the simulation parameters, namely the input and output heat, corresponding to the stimulation and natural convection. The simulations and the analysis of their results focus on the heat flow inside the sample and the manner they change for different geometries. This was performed for poly(methyl methacrylate (PMMA) and carbon fiber-reinforced polymers (CFRPs). The simulation of these materials was also used to create prediction surfaces and equations. These predict the amplitude and phase for a sample with a thickness l and a cycle period. These new findings were validated with new laboratory tests and two new samples. These validated the prediction surfaces and equations and can now be used as a reference for future works and industrial applications. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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23 pages, 11862 KiB

Open AccessArticle

Raspberry Pi Platform Wireless Sensor Node for Low-Frequency Impedance Responses of PZT Interface

by Quang-Quang Pham, Quoc-Bao Ta, Jae-Hyung Park and Jeong-Tae Kim

Sensors 2022, 22(24), 9592; https://doi.org/10.3390/s22249592 - 7 Dec 2022

Cited by 12 | Viewed by 2494

Abstract

A wireless impedance monitoring system, called SSeL-Pi, is designed to have cheap, mobile, and handy practical features as compared to wired commercial impedance analyzers. A Raspberry Pi platform impedance sensor node is designed to measure signals at a low-frequency range of up to [...] Read more.

A wireless impedance monitoring system, called SSeL-Pi, is designed to have cheap, mobile, and handy practical features as compared to wired commercial impedance analyzers. A Raspberry Pi platform impedance sensor node is designed to measure signals at a low-frequency range of up to 100 kHz. The low-frequency impedance measurement via the proposed node has been combined with a new PZT interface technique for measuring local responses sensitive to structural damage. The new PZT interface can work as a surface-mounted or embedded sensor, and its local dynamic characteristics are numerically analyzed to pre-determine an effective impedance resonant frequency range of less than 100 kHz. Next, a software scheme was designed to visualize the input/output parameters of the proposed SSeL-Pi system (i.e., Raspberry Pi platform and PZT interface) and automate signal acquisition procedures of the impedance sensor node. The calibration for impedance signals obtained from the proposed system was performed by a series of procedures, from acquiring real and imaginary impedance to adjusting them with respect to a commercial impedance analyzer (HIOKI-3532). The feasibility of the wireless impedance monitoring system was experimentally evaluated for PZT interfaces that were subjected to various compressive loadings. The consistent results analyzed from signals measured by the SSeL-Pi and HIOKI 3532 systems were observed. Additionally, the strong relationships between impedance features (frequency shift and RMSD index) and compressive stresses of the PZT interfaces showed the potential for axial force/stress variation monitoring in real structures using the Raspberry Pi platform impedance sensor node and developed PZT interface. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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16 pages, 4107 KiB

Open AccessArticle

Research on Inherent Frequency and Vibration Characteristics of Sandwich Piezoelectric Ceramic Transducer

by Yuren Lu, Chunguang Xu, Qinxue Pan, Quanpeng Yu and Dingguo Xiao

Sensors 2022, 22(23), 9431; https://doi.org/10.3390/s22239431 - 2 Dec 2022

Cited by 1 | Viewed by 2638

Abstract

Great progress has been made in the field of ultrasonic processing in recent years, and piezoelectric ceramic transducers have been widely used as drive sources. In this paper, a sandwich piezoelectric ceramic transducer is designed, and the vibration of each part of the [...] Read more.

Great progress has been made in the field of ultrasonic processing in recent years, and piezoelectric ceramic transducers have been widely used as drive sources. In this paper, a sandwich piezoelectric ceramic transducer is designed, and the vibration of each part of the transducer is analyzed by elastic mechanics and piezoelectric theory. According to its mechanical and electrical boundary conditions, the vibration model of the piezoelectric transducer was established. Based on the equivalent elastic modulus method for simplifying the pre-stressed bolts into a one-dimensional transducer vibration model, the relationship between the one-dimensional axial response frequency of the transducer and the length of each component was obtained. Based on the half wavelength theory, a transducer with the vibration node in the crystal stack and an inherent frequency of 15 kHz was designed and fabricated. In order to verify the natural frequency and vibration characteristics of the piezoelectric transducer, a laser vibration measurement system was built in this study. The vibration characteristics of the transducer under different parameters such as voltage and frequency were analyzed, and the accuracy of the vibration model was verified. The vibration states of the end surface of the transducer and the radial surface were evaluated at the first-order inherent frequency and second-order inherent frequency. The results show that the equivalent simplified model established in this study can effectively design the inherent frequency of the transducer, and the operation at the first-order inherent frequency meets the one-dimensional assumptions of this study. The transducer operating conditions measured in this study also provide a more detailed reference for ultrasonic processing applications. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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27 pages, 15777 KiB

Open AccessArticle

The Smart Nervous System for Cracked Concrete Structures: Theory, Design, Research, and Field Proof of Monolithic DFOS-Based Sensors

by Łukasz Bednarski, Rafał Sieńko, Tomasz Howiacki and Katarzyna Zuziak

Sensors 2022, 22(22), 8713; https://doi.org/10.3390/s22228713 - 11 Nov 2022

Cited by 13 | Viewed by 2457

Abstract

The article presents research on the performance of composite and monolithic sensors for distributed fibre optic sensing (DFOS). The introduction summarises the design of the sensors and the theoretical justification for such an approach. Lessons learned during monitoring cracked concrete are summarised to [...] Read more.

The article presents research on the performance of composite and monolithic sensors for distributed fibre optic sensing (DFOS). The introduction summarises the design of the sensors and the theoretical justification for such an approach. Lessons learned during monitoring cracked concrete are summarised to highlight what features of the DFOS tools are the most favourable from the crack analysis point of view. Later, the results from full-size laboratory concrete specimens working in a cracked state were presented and discussed in reference to conventional layered sensing cables. The research aimed to compare monolithic sensors and layered cables embedded in the same reinforced concrete elements, which is the main novelty. The performance of each DFOS nondestructive tool was investigated in the close vicinity of the cracks—both the new ones, opening within the tension zone, and the existing ones, closing within the compression zone. The qualitative (detection) and quantitative (widths estimation) crack analyses were performed and discussed. Finally, the examples of actual applications within concrete structures, including bridges, are presented with some examples of in situ results. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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11 pages, 4088 KiB

Open AccessArticle

Evaluation of Axial Preload in Different-Frequency Smart Bolts by Laser Ultrasound

by Guanpin Ren, Huan Zhan, Ziqian Liu, Wei Jiang, Ru Li and Shuang Liu

Sensors 2022, 22(22), 8665; https://doi.org/10.3390/s22228665 - 10 Nov 2022

Cited by 5 | Viewed by 2011

Abstract

We report here on a laser ultrasonic system to indirectly evaluate the preload force of different-frequency piezoelectric bolts. This newly developed system enables us to achieve the goal of non-contact excitation and synchronously collects the laser-induced ultrasonic signal by the combination of a [...] Read more.

We report here on a laser ultrasonic system to indirectly evaluate the preload force of different-frequency piezoelectric bolts. This newly developed system enables us to achieve the goal of non-contact excitation and synchronously collects the laser-induced ultrasonic signal by the combination of a smart piezoelectric sensor and a magnetically mounted transducer connector. A numerical model based on the finite element method (FEM) was developed to simulate the propagation and displacement distribution of laser-generated ultrasonic waves along the axial direction. The measured A-scan waveform basically coincided with the counterpart obtained from a theoretical simulation, confirming the effectiveness of the proposed system to measure a bolt. By comparison, a laser spot diameter of 6 mm was the optimal beam diameter for the excitation of the ultrasonic wave in the bolt. The linear relationship between time of flight (TOF) of the ultrasonic longitudinal wave and bolt torque was almost independent from the center frequency of the smart bolt. By contrast, a piezoelectric patch centered at 5 MHz was more suitable as an ultrasonic sensor in terms of the nonlinear effects component suppression and linear fitting degree between TOF and torque. The results indicate that the proposed system based on a surface-mounted piezoelectric sensor is a promising system for evaluating the axial preload change of connector and fastener and is an additional potential laser ultrasonic system for nondestructive tests. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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17 pages, 11985 KiB

Open AccessArticle

Extending the Incidence Angle of Shear Vertical Wave Electromagnetic Acoustic Transducer with Horizontal Magnetization

by Zhengyang Qu, Zhichao Li, Runjie Yang, Songtao Hu and Shujuan Wang

Sensors 2022, 22(22), 8589; https://doi.org/10.3390/s22228589 - 8 Nov 2022

Cited by 2 | Viewed by 2030

Abstract

Angled shear vertical (SV) waves have been successfully employed in the non-destructive testing of welds, pipes, and railways. Non-contact meander-line coil electromagnetic acoustic transducers (EMAT) have many benefits in generating angled SV waves. The most important benefit is that the incidence angle of [...] Read more.

Angled shear vertical (SV) waves have been successfully employed in the non-destructive testing of welds, pipes, and railways. Non-contact meander-line coil electromagnetic acoustic transducers (EMAT) have many benefits in generating angled SV waves. The most important benefit is that the incidence angle of an SV wave can be controlled by the excitation frequency. However, the incidence angle of a traditional SV-wave EMAT is reported to be under 45 degrees in many cases. In this work, such cases are tested, and the problems of the received signal at large incidence angles are found to be due to wave interference and small signal amplitudes. An equivalent finite element (FE) model is established to analyze the problem, and the main reason is found to be the head wave. An alternative configuration of angled SV-wave EMAT with horizontal magnetization is proposed to reduce the influence of the head wave. Finally, the results from simulations and experiments show that the proposed EMAT has a larger signal amplitude and significantly reduced interference in large-incidence angle scenarios. Moreover, an incidence angle of an SV wave of up to 60 degrees can be achieved, which will help improve the performance and capability of nondestructive testing. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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20 pages, 14697 KiB

Open AccessArticle

Small Ultrasound-Based Corrosion Sensor for Intraday Corrosion Rate Estimation

by Upeksha Chathurani Thibbotuwa, Ainhoa Cortés and Andoni Irizar

Sensors 2022, 22(21), 8451; https://doi.org/10.3390/s22218451 - 3 Nov 2022

Cited by 2 | Viewed by 2409

Abstract

The conventional way of studying corrosion in marine environments is by installing corrosion coupons. Instead, this paper presents an experimental field study using an unattended corrosion sensor developed on the basis of ultrasound (US) technology to assess the thickness loss caused by general [...] Read more.

The conventional way of studying corrosion in marine environments is by installing corrosion coupons. Instead, this paper presents an experimental field study using an unattended corrosion sensor developed on the basis of ultrasound (US) technology to assess the thickness loss caused by general atmospheric corrosion on land close to the sea (coastal region). The system described here uses FPGA, low-power microcontroller, analog front-end devices in the sensor node, and a Beaglebone black wireless board for posting data to a server. The overall system is small, operates at low power, and was deployed at Gran Canaria to detect the thickness loss of an S355 steel sample and consequently estimate the corrosion rate. This experiment aims to demonstrate the system’s viability in marine environments and its potential to monitor corrosion in offshore wind turbines. In a day, the system takes four sets of measurements in 6 hour intervals, and each set consists of 5 consecutive measurements. Over the course of 5 months, the proposed experiment allowed for us to continuously monitor the corrosion rate in an equivalent corrosion process to an average thickness loss rate of 0.134 mm/year. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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18 pages, 12141 KiB

Open AccessArticle

An Improved RAPID Imaging Method of Defects in Composite Plate Based on Feature Identification by Machine Learning

by Fei Deng, Xiran Zhang, Ning Yu and Lin Zhao

Sensors 2022, 22(21), 8413; https://doi.org/10.3390/s22218413 - 1 Nov 2022

Cited by 1 | Viewed by 1480

Abstract

The RAPID (reconstruction algorithm for probabilistic inspection of defect) method based on Lamb wave detection is an effective method to give the position information of a defect in composite plate. In this paper, an improved RAPID imaging method based on machine learning (ML) [...] Read more.

The RAPID (reconstruction algorithm for probabilistic inspection of defect) method based on Lamb wave detection is an effective method to give the position information of a defect in composite plate. In this paper, an improved RAPID imaging method based on machine learning (ML) is proposed to precisely visualize the location and features of defects in composite plate. First, the specific feature information of the defect, such as type, size and direction, can be identified by analyzing the detection signals through multiple machine learning models. Then, according to the obtained defect features, the scaling parameter β of the RAPID method which controls the size of the elliptical area is revised, and weights are set to the important detection paths which are related to defect features to realize precise defect imaging. The simulation results show that the proposed method can intuitively characterize the location and related feature information of the defect, and effectively improve the accuracy of defect imaging. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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16 pages, 7567 KiB

Open AccessArticle

Characterization of Tensile Stress-Dependent Directional Magnetic Incremental Permeability in Iron-Cobalt Magnetic Sheet: Towards Internal Stress Estimation through Non-Destructive Testing

by Borel Toutsop, Benjamin Ducharne, Mickael Lallart, Laurent Morel and Pierre Tsafack

Sensors 2022, 22(16), 6296; https://doi.org/10.3390/s22166296 - 21 Aug 2022

Cited by 6 | Viewed by 2621

Abstract

Iron-Cobalt ferromagnetic alloys are promoted for electrical energy conversion in aeronautic applications, but their high magnetostrictive coefficients may result in undesired behaviors. Internal stresses can be tuned to limit magnetostriction but must be adequately assessed in a non-destructive way during production. For this, [...] Read more.

Iron-Cobalt ferromagnetic alloys are promoted for electrical energy conversion in aeronautic applications, but their high magnetostrictive coefficients may result in undesired behaviors. Internal stresses can be tuned to limit magnetostriction but must be adequately assessed in a non-destructive way during production. For this, directional magnetic incremental permeability is proposed in this work. For academic purposes, internal stresses have been replaced by homogenous external stress, which is easier to control using traction/compression testbench and results in similar effects. Tests have been limited to tensile stress stimuli, the worst-case scenario for magnetic stress observation on positive magnetostriction coefficient materials. Hysteresis cycles have been reconstructed from the incremental permeability measurement for stability and reproducibility of the measured quantities. The directionality of the sensor provides an additional degree of freedom in the magnetic response observation. The study reveals that an angle of π/2 between the DC (H_{surf DC}) and the AC (H_{surf AC}) magnetic excitations with a flux density B_a at H_surf_DC = 10 kA·m⁻¹ constitute the ideal experimental situation and the highest correlated parameter to a homogeneous imposed tensile stress. Magnetic incremental permeability is linked to the magnetic domain wall bulging magnetization mechanism; this study thus provides insights for understanding such a mechanism. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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17 pages, 6000 KiB

Open AccessArticle

3D Measurement of Large Deformations on a Tensile Structure during Wind Tunnel Tests Using Microsoft Kinect V2

by Daniele Marchisotti, Paolo Schito and Emanuele Zappa

Sensors 2022, 22(16), 6149; https://doi.org/10.3390/s22166149 - 17 Aug 2022

Viewed by 1546

Abstract

Wind tunnel tests often require deformation and displacement measures to determine the behavior of structures to evaluate their response to wind excitation. However, common measurement techniques make it possible to measure these quantities only at a few specific points. Moreover, these kinds of [...] Read more.

Wind tunnel tests often require deformation and displacement measures to determine the behavior of structures to evaluate their response to wind excitation. However, common measurement techniques make it possible to measure these quantities only at a few specific points. Moreover, these kinds of measurements, such as Linear Variable Differential Transformer LVDTs or fiber optics, usually influence the downstream and upstream air fluxes and the structure under test. In order to characterize the displacement of the structure not just at a few points, but for the entire structure, in this article, the application of 3D cameras during a wind tunnel test is presented. In order to validate this measurement technique in this application field, a wind tunnel test was executed. Three Kinect V2 depth sensors were used for a 3D displacement measurement of a test structure that did not present any optical marker or feature. The results highlighted that by using a low-cost and user-friendly measurement system, it is possible to obtain 3D measurements in a volume of several cubic meters (4 m × 4 m × 4 m wind tunnel chamber), without significant disturbance of wind flux and by means of a simple calibration of sensors, executed directly inside the wind tunnel. The obtained results highlighted a displacement directed to the internal part of the structure for the side most exposed to wind, while the sides, parallel to the wind flux, were more subjected to vibrations and with an outwards average displacement. These results are compliant with the expected behavior of the structure. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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15 pages, 5003 KiB

Open AccessArticle

Modeling Full-Field Transient Flexural Waves on Damaged Plates with Arbitrary Excitations Using Temporal Vibration Characteristics

by Dan-Feng Wang, Kuo-Chih Chuang, Jun-Jie Liu and Chan-Yi Liao

Sensors 2022, 22(16), 5958; https://doi.org/10.3390/s22165958 - 9 Aug 2022

Cited by 1 | Viewed by 1627

Abstract

We propose an efficient semi-analytical method capable of modeling the propagation of flexural waves on cracked plate structures with any forms of excitations, based on the same group of vibration characteristics and validated by a non-contact scanning Laser Doppler Vibrometer (LDV) system. The [...] Read more.

We propose an efficient semi-analytical method capable of modeling the propagation of flexural waves on cracked plate structures with any forms of excitations, based on the same group of vibration characteristics and validated by a non-contact scanning Laser Doppler Vibrometer (LDV) system. The proposed modeling method is based on the superposition of the vibrational normal modes of the detected structure, which can be applied to analyze long-time and full-field transient wave propagations. By connecting the vibration-based transient model to a power flow analysis technique, we further analyze the transient waves on a cracked plate subjected to different excitation sources and show the influence of the damage event on the path of the propagating waves. The experimental results indicate that the proposed semi-analytical method can model the flexural waves, and through that, the crack information can be revealed. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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18 pages, 3330 KiB

Open AccessArticle

Concrete Curing Performance Assessment Based on Gas Permeability Testing in the Lab and on Site

by Lisa Ptacek, Alfred Strauss, Clémence Bos, Martin Peyerl and Roberto Torrent

Sensors 2022, 22(13), 4672; https://doi.org/10.3390/s22134672 - 21 Jun 2022

Cited by 5 | Viewed by 1700

Abstract

Durability is an essential aspect of the lifetime performance of concrete components. The adequate surface quality and thus the service life of concrete can be achieved, among other things, by appropriate curing during hydration. To measure and control the curing quality, appropriate procedures [...] Read more.

Durability is an essential aspect of the lifetime performance of concrete components. The adequate surface quality and thus the service life of concrete can be achieved, among other things, by appropriate curing during hydration. To measure and control the curing quality, appropriate procedures are required. Gas permeability allows conclusions to be drawn about the porosity of concrete, which has a significant impact on durability. In this contribution, the effect of different curing methods on gas permeability is presented with the help of laboratory and on-site tests, showing that inadequate curing leads to increased permeability in the near-surface area of concrete. The measurement results of concrete samples and components with the same composition but varying curing treatment are compared and evaluated. Influences such as concrete composition and environmental factors on the quality of concrete are observed, and recommendations are made for a reliable assessment of the surface quality as a result of the investigated curing measures. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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16 pages, 3704 KiB

Open AccessArticle

Lamb Waves Propagation Characteristics in Functionally Graded Sandwich Plates

by Jie Gao, Jianbo Zhang, Yan Lyu, Guorong Song and Cunfu He

Sensors 2022, 22(11), 4052; https://doi.org/10.3390/s22114052 - 27 May 2022

Cited by 3 | Viewed by 2214

Abstract

Functionally graded materials (FGM) have received extensive attention in recent years due to their excellent mechanical properties. In this research, the theoretical process of calculating the propagation characteristics of Lamb waves in FGM sandwich plates is deduced by combining the FGM volume fraction [...] Read more.

Functionally graded materials (FGM) have received extensive attention in recent years due to their excellent mechanical properties. In this research, the theoretical process of calculating the propagation characteristics of Lamb waves in FGM sandwich plates is deduced by combining the FGM volume fraction curve and Legendre polynomial series expansion method. In this proposed method, the FGM plate does not have to be sliced into multiple layers. Numerical results are given in detail, and the Lamb wave dispersion curves are extracted. For comparison, the Lamb wave dispersion curve of the sliced layer model for the FGM sandwich plate is obtained by the global matrix method. Meanwhile, the FGM sandwich plate was subjected to finite element simulation, also based on the layered-plate model. The acoustic characteristics detection experiment was performed by simulation through a defocusing measurement. Thus, the Lamb wave dispersion curves were obtained by V(f, z) analysis. Finally, the influence of the change in the gradient function on the Lamb wave dispersion curves will be discussed. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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17 pages, 4964 KiB

Open AccessArticle

Pulse-Modulation Eddy Current Evaluation of Interlaminar Corrosion in Stratified Conductors: Semi-Analytical Modeling and Experiments

by Zhengshuai Liu, Yong Li, Shuting Ren, Yanzhao Ren, Ilham Mukriz Zainal Abidin and Zhenmao Chen

Sensors 2022, 22(9), 3458; https://doi.org/10.3390/s22093458 - 1 May 2022

Cited by 7 | Viewed by 1883

Abstract

Interlaminar corrosion (ILC) poses a severe threat to stratified conductors which are broadly employed in engineering fields including aerospace, energy, etc. Therefore, for the pressing concern regarding the safety and integrity of stratified conductors, it is imperative to non-intrusively and quantitatively interrogate ILC [...] Read more.

Interlaminar corrosion (ILC) poses a severe threat to stratified conductors which are broadly employed in engineering fields including aerospace, energy, etc. Therefore, for the pressing concern regarding the safety and integrity of stratified conductors, it is imperative to non-intrusively and quantitatively interrogate ILC via non-destructive evaluation techniques. In this paper, pulse-modulation eddy current (PMEC) for imaging and assessment of ILC is intensively investigated through theoretical simulations and experiments. A semi-analytical model of PMEC evaluation of ILC occurring at the interlayer of two conductor layers is established based on the extended truncated region eigenfunction expansion (ETREE) along with the efficient algorithm for the numerical computation of eigenvalues for reflection coefficients of the stratified conductor under inspection. Based on theoretical investigation, PMEC evaluation of ILC in testing samples are further scrutinized by using the PMEC imaging system built up for the experimental study. The theoretical and experimental results have revealed the feasibility of PMEC for imaging and evaluation of ILC in stratified conductors. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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17 pages, 3267 KiB

Open AccessArticle

Acoustic Emission Source Location Using Finite Element Generated Delta-T Mapping

by Han Yang, Bin Wang, Stephen Grigg, Ling Zhu, Dandan Liu and Ryan Marks

Sensors 2022, 22(7), 2493; https://doi.org/10.3390/s22072493 - 24 Mar 2022

Cited by 8 | Viewed by 2681

Abstract

One of the most significant benefits of Acoustic Emission (AE) testing over other Non-Destructive Evaluation (NDE) techniques lies in its damage location capability over a wide area. The delta-T mapping technique developed by researchers has been shown to enable AE source location to [...] Read more.

One of the most significant benefits of Acoustic Emission (AE) testing over other Non-Destructive Evaluation (NDE) techniques lies in its damage location capability over a wide area. The delta-T mapping technique developed by researchers has been shown to enable AE source location to a high level of accuracy in complex structures. However, the time-consuming and laborious data training process of the delta-T mapping technique has prevented this technique from large-scale application on large complex structures. In order to solve this problem, a Finite Element (FE) method was applied to model training data for localization of experimental AE events on a complex plate. Firstly, the FE model was validated through demonstrating consistency between simulated data and the experimental data in the study of Hsu-Nielsen (H-N) sources on a simple plate. Then, the FE model with the same parameters was applied to a planar location problem on a complex plate. It has been demonstrated that FE generated delta-T mapping data can achieve a reasonable degree of source location accuracy with an average error of 3.88 mm whilst decreasing the time and effort required for manually collecting and processing the training data. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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16 pages, 6213 KiB

Open AccessArticle

A New Probabilistic Ellipse Imaging Method Based on Adaptive Signal Truncation for Ultrasonic Guided Wave Defect Localization on Pressure Vessels

by Qinfei Li, Zhi Luo, Gangyi Hu and Shaoping Zhou

Sensors 2022, 22(4), 1540; https://doi.org/10.3390/s22041540 - 17 Feb 2022

Cited by 4 | Viewed by 1996

Abstract

Pressure vessels are prone to defects due to environmental conditions, which may cause serious safety hazards to industrial production. The probabilistic ellipse imaging method, based on ultrasonic guided wave, is a common method for locating defects on plate-like structures. In this paper, the [...] Read more.

Pressure vessels are prone to defects due to environmental conditions, which may cause serious safety hazards to industrial production. The probabilistic ellipse imaging method, based on ultrasonic guided wave, is a common method for locating defects on plate-like structures. In this paper, the research showed that the accuracy of the traditional probabilistic ellipse imaging method was severely affected by the truncation length of the signal. In order to improve the defect location accuracy of the probabilistic elliptic imaging algorithm, an adaptive signal truncation method based on signal difference analysis was proposed, and a novel probabilistic elliptic imaging method was developed. Firstly, the relationship model between the signal difference coefficient (SDC) and the distance coefficient was constructed. Through this model, the distance coefficient of each group signal can be calculated, so that the adaptive truncation length for each group of signals can be determined and the truncated signals used for defect imaging. Secondly, in order to improve the robustness of the new imaging method, the relationship between the defect location accuracy and SDC thresholds were investigated and the optimal threshold was determined. The experimental results showed that the probabilistic ellipse imaging algorithm, based on the new adaptive signal truncation method, can effectively locate a single defect on a pressure vessel. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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13 pages, 4776 KiB

Open AccessArticle

Modeling and Analysis of Acoustic Emission Generated by Fatigue Cracking

by Weilei Mu, Yuqing Gao, Yuxue Wang, Guijie Liu and Hao Hu

Sensors 2022, 22(3), 1208; https://doi.org/10.3390/s22031208 - 5 Feb 2022

Cited by 9 | Viewed by 3146

Abstract

The acoustic emission (AE) method is a popular and well-developed method for passive structural health monitoring of metallic and composite structures. The current study focuses on the analysis of one of its processes, sound source or signal propagation. This paper discusses the principle [...] Read more.

The acoustic emission (AE) method is a popular and well-developed method for passive structural health monitoring of metallic and composite structures. The current study focuses on the analysis of one of its processes, sound source or signal propagation. This paper discusses the principle of plate wave signal sensing using piezoelectric transducers, and derives an analytical expression for the response of piezoelectric transducers under the action of stress waves, to obtain an overall mathematical model of the acoustic emission signal from generation to reception. The acoustic emission caused by fatigue crack extension is simulated by a finite element method, and the actual acoustic emission signal is simulated by a pencil lead break experiment. The results predicted by the mathematical model are compared with the experimental results and the simulation results, respectively, and show good agreement. In addition, the presence of obvious S0 mode Lamb waves is observed in the simulation results and experimental results, which further verifies the correctness of the analytical model prediction. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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15 pages, 26456 KiB

Open AccessArticle

TR Self-Adaptive Cancellation Based Pipeline Leakage Localization Method Using Piezoceramic Transducers

by Yanbin Mo and Lvqing Bi

Sensors 2022, 22(2), 696; https://doi.org/10.3390/s22020696 - 17 Jan 2022

Cited by 1 | Viewed by 1863

Abstract

In this paper, we propose a novel time reversal-based localization method for pipeline leakage. In the proposed method, a so-called TR self-adaptive cancellation is developed to improve the leak localization resolution. First of all, the proposed approach time reverses and back-propagates the captured [...] Read more.

In this paper, we propose a novel time reversal-based localization method for pipeline leakage. In the proposed method, a so-called TR self-adaptive cancellation is developed to improve the leak localization resolution. First of all, the proposed approach time reverses and back-propagates the captured signals. Secondly, the time reversed signals with the various coefficients are superposed. Due to the synchronous temporal and spatial focusing characteristic of time reversal, those time reversed signals will cancel each other out. Finally, the leakage location is distinguished by observing the energy distribution of the superposed signal. In this investigation, the proposed method was employed to monitor a 58 m PVC pipeline. Three manually controllable valves were utilized to simulate the leakages. Six piezoceramic sensors equipped on the pipeline, recorded the NWP signals generated by the three valves. The experimental results show that the leak positions can accurately revealed by using the proposed approach. Furthermore, the resolution of the proposed approach can be ten times that of the conventional TR localization method. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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13 pages, 25164 KiB

Open AccessArticle

Strength Development Monitoring of Cemented Paste Backfill Using Guided Waves

by Wen He, Changsong Zheng, Shenhai Li, Wenfang Shi and Kui Zhao

Sensors 2021, 21(24), 8499; https://doi.org/10.3390/s21248499 - 20 Dec 2021

Cited by 3 | Viewed by 2678

Abstract

The strength of cemented paste backfill (CPB) directly affects mining safety and progress. At present, in-situ backfill strength is obtained by conducting uniaxial compression tests on backfill core samples. At the same time, it is time-consuming, and the integrity of samples cannot be [...] Read more.

The strength of cemented paste backfill (CPB) directly affects mining safety and progress. At present, in-situ backfill strength is obtained by conducting uniaxial compression tests on backfill core samples. At the same time, it is time-consuming, and the integrity of samples cannot be guaranteed. Therefore guided wave technique as a nondestructive inspection method is proposed for the strength development monitoring of cemented paste backfill. In this paper, the acoustic parameters of guided wave propagation in the different cement-tailings ratios (1:4, 1:8) and different curing times (within 42 d) of CPBs were measured. Combined with the uniaxial compression strength of CPB, relationships between CPB strength and the guided wave acoustic parameters were established. Results indicate that with the increase of backfill curing time, the guided wave velocity decreases sharply at first; on the contrary, attenuation of guided waves increases dramatically. Finally, both velocity and attenuation tend to be stable. When the CPB strength increases with curing time, guided wave velocity shows an exponentially decreasing trend, while the guided wave attenuation shows an exponentially increasing trend with the increase of the CPB strength. Based on the relationship curves between CPB strength and guided wave velocity and attenuation, the guided wave technique in monitoring the strength development of CPB proves feasible. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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19 pages, 6212 KiB

Open AccessArticle

Ultrasound Defect Localization in Shell Structures with Lamb Waves Using Spare Sensor Array and Orthogonal Matching Pursuit Decomposition

by Weilei Mu, Yuqing Gao and Guijie Liu

Sensors 2021, 21(23), 8127; https://doi.org/10.3390/s21238127 - 4 Dec 2021

Cited by 10 | Viewed by 2822

Abstract

Lamb waves have multimodal and dispersion effects, which reduces their performance in damage localization with respect to resolution. To detect damage with fewest sensors and high resolution, a method, using only two piezoelectric transducers and based on orthogonal matching pursuit (OMP) decomposition, was [...] Read more.

Lamb waves have multimodal and dispersion effects, which reduces their performance in damage localization with respect to resolution. To detect damage with fewest sensors and high resolution, a method, using only two piezoelectric transducers and based on orthogonal matching pursuit (OMP) decomposition, was proposed. First, an OMP-based decomposition and dispersion removal algorithm is introduced, which is capable of separating wave packets of different propagation paths and removing the dispersion part successively. Then, two simulation signals, with nonoverlapped and overlapped wave packets, are employed to verify the proposed method. Thereafter, with the proposed algorithm, the wave packets reflected from the defect and edge are all separated. Finally, a sparse sensor array with only two transducers succeeds in localizing the defect. The experimental results show that the OMP-based algorithm is beneficial for resolution improvement and transducer usage reduction. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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18 pages, 3620 KiB

Open AccessArticle

An Intelligence Method for Recognizing Multiple Defects in Rail

by Fei Deng, Shu-Qing Li, Xi-Ran Zhang, Lin Zhao, Ji-Bing Huang and Cheng Zhou

Sensors 2021, 21(23), 8108; https://doi.org/10.3390/s21238108 - 3 Dec 2021

Cited by 11 | Viewed by 2220

Abstract

Ultrasonic guided waves are sensitive to many different types of defects and have been studied for defect recognition in rail. However, most fault recognition algorithms need to extract features from the time domain, frequency domain, or time-frequency domain based on experience or professional [...] Read more.

Ultrasonic guided waves are sensitive to many different types of defects and have been studied for defect recognition in rail. However, most fault recognition algorithms need to extract features from the time domain, frequency domain, or time-frequency domain based on experience or professional knowledge. This paper proposes a new method for identifying many different types of rail defects. The segment principal components analysis (S-PCA) is developed to extract characteristics from signals collected by sensors located at different positions. Then, the Support Vector Machine (SVM) model is used to identify different defects depending on the features extracted. Combining simulations and experiments of the rails with different kinds of defects are established to verify the effectiveness of the proposed defect identification techniques, such as crack, corrosion, and transverse crack under the shelling. There are nine channels of the excitation-reception to acquire guided wave detection signals. The results show that the defect classification accuracy rates are 96.29% and 96.15% for combining multiple signals, such as the method of single-point excitation and multi-point reception, or the method of multi-point excitation and reception at a single point. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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27 pages, 14201 KiB

Open AccessArticle

Nonlinear Ultrasound Crack Detection with Multi-Frequency Excitation—A Comparison

by Frank Mevissen and Michele Meo

Sensors 2021, 21(16), 5368; https://doi.org/10.3390/s21165368 - 9 Aug 2021

Cited by 3 | Viewed by 3067

Abstract

Nonlinear ultrasound crack detection methods are used as modern, non-destructive testing tools for inspecting early damages in various materials. Nonlinear ultrasonic wave modulation, where typically two or more frequencies are excited, was demonstrated to be a robust method for failure indicators when using [...] Read more.

Nonlinear ultrasound crack detection methods are used as modern, non-destructive testing tools for inspecting early damages in various materials. Nonlinear ultrasonic wave modulation, where typically two or more frequencies are excited, was demonstrated to be a robust method for failure indicators when using measured harmonics and modulated response frequencies. The aim of this study is to address the capability of multi-frequency wave excitation, where more than two excitation frequencies are used, for better damage identification when compared to single and double excitation frequencies without the calculation of dispersion curves. The excitation frequencies were chosen in such a way that harmonic and modulated response frequencies meet at a specific frequency to amplify signal energy. A new concept of nonlinearity parameter grouping with multi-frequency excitation was developed as an early failure parameter. An analytical solution of the one-dimensional wave equation was derived with four fundamental frequencies, and a total of 64 individual and 30 group nonlinearity parameters. Experimental validation of the approach was conducted on metal plates with different types of cracks and on turbine blades where cracks originated under service conditions. The results showed that the use of multi-frequency excitation offers advantages in detecting cracks. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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16 pages, 6817 KiB

Open AccessArticle

Negative Index Metamaterial Lens for Subwavelength Microwave Detection

by Srijan Datta, Saptarshi Mukherjee, Xiaodong Shi, Mahmood Haq, Yiming Deng, Lalita Udpa and Edward Rothwell

Sensors 2021, 21(14), 4782; https://doi.org/10.3390/s21144782 - 13 Jul 2021

Cited by 10 | Viewed by 4962

Abstract

Metamaterials are engineered periodic structures designed to have unique properties not encountered in naturally occurring materials. One such unusual property of metamaterials is the ability to exhibit negative refractive index over a prescribed range of frequencies. A lens made of negative refractive index [...] Read more.

Metamaterials are engineered periodic structures designed to have unique properties not encountered in naturally occurring materials. One such unusual property of metamaterials is the ability to exhibit negative refractive index over a prescribed range of frequencies. A lens made of negative refractive index metamaterials can achieve resolution beyond the diffraction limit. This paper presents the design of a metamaterial lens and its use in far-field microwave imaging for subwavelength defect detection in nondestructive evaluation (NDE). Theoretical formulation and numerical studies of the metamaterial lens design are presented followed by experimental demonstration and characterization of metamaterial behavior. Finally, a microwave homodyne receiver-based system is used in conjunction with the metamaterial lens to develop a far-field microwave NDE sensor system. A subwavelength focal spot of size 0.82λ was obtained. The system is shown to be sensitive to a defect of size 0.17λ × 0.06λ in a Teflon sample. Consecutive positions of the defect with a separation of 0.23λ was resolvable using the proposed system. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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15 pages, 5610 KiB

Open AccessArticle

Coherent Fiber-Optic Sensor for Ultra-Acoustic Crack Emissions

by Ilaria Di Luch, Maddalena Ferrario, Davide Fumagalli, Michele Carboni and Mario Martinelli

Sensors 2021, 21(14), 4674; https://doi.org/10.3390/s21144674 - 8 Jul 2021

Cited by 3 | Viewed by 3331

Abstract

A coherent optical fiber sensor with adequate sensitivity for detecting the acoustic emission (AE) during the propagation of a crack in a ferrous material is presented. The proposed fiber optic sensor is successfully compared in terms of the SNR (Signal to Noise Ratio) [...] Read more.

A coherent optical fiber sensor with adequate sensitivity for detecting the acoustic emission (AE) during the propagation of a crack in a ferrous material is presented. The proposed fiber optic sensor is successfully compared in terms of the SNR (Signal to Noise Ratio) and detectable AE energy levels to commercially available AE piezo-transducers sensors and is proven to be an effective and advantageous alternative for sensing and monitoring fatigue damage in structural applications. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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14 pages, 61494 KiB

Open AccessArticle

Quantifying Hole-Edge Crack of Bolt Joints by Using an Embedding Triangle Eddy Current Sensing Film

by Shilei Fan, Junyan Yi, Hu Sun and Fenglin Yun

Sensors 2021, 21(7), 2567; https://doi.org/10.3390/s21072567 - 6 Apr 2021

Cited by 5 | Viewed by 3121

Abstract

Hole-edge crack quantification of bolt joints is critical for monitoring and estimating structural integrity of aircraft. The paper proposes a new triangle eddy current sensor array for the purpose of increasing the level of quantifying hole-edge crack parameters, especially, the crack angle. The [...] Read more.

Hole-edge crack quantification of bolt joints is critical for monitoring and estimating structural integrity of aircraft. The paper proposes a new triangle eddy current sensor array for the purpose of increasing the level of quantifying hole-edge crack parameters, especially, the crack angle. The new senor array consists of triangular coils instead of planar rectangular coils. The configuration of the novel sensor array, including the excitation current directions and the excitation winding shape, is optimized by simulation. The ability of the proposed sensing film to identify the crack parameters has been verified by finite element simulations and experiments. Results shows that triangular coils with same current directions in circumferentially adjacent coils and opposite current directions in axially adjacent coils achieve better performance in sensor linearity and resolution compared to rectangular coils. In addition, it has also been proved that the sensing film has a good potential to identify the crack depth and length. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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Review

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28 pages, 5504 KiB

Open AccessEditor’s ChoiceReview

Low-Cost Technologies Used in Corrosion Monitoring

by Mahyad Komary, Seyedmilad Komarizadehasl, Nikola Tošić, I. Segura, Jose Antonio Lozano-Galant and Jose Turmo

Sensors 2023, 23(3), 1309; https://doi.org/10.3390/s23031309 - 23 Jan 2023

Cited by 32 | Viewed by 6807

Abstract

Globally, corrosion is the costliest cause of the deterioration of metallic and concrete structures, leading to significant financial losses and unexpected loss of life. Therefore, corrosion monitoring is vital to the assessment of structures’ residual performance and for the identification of pathologies in [...] Read more.

Globally, corrosion is the costliest cause of the deterioration of metallic and concrete structures, leading to significant financial losses and unexpected loss of life. Therefore, corrosion monitoring is vital to the assessment of structures’ residual performance and for the identification of pathologies in early stages for the predictive maintenance of facilities. However, the high price tag on available corrosion monitoring systems leads to their exclusive use for structural health monitoring applications, especially for atmospheric corrosion detection in civil structures. In this paper a systematic literature review is provided on the state-of-the-art electrochemical methods and physical methods used so far for corrosion monitoring compatible with low-cost sensors and data acquisition devices for metallic and concrete structures. In addition, special attention is paid to the use of these devices for corrosion monitoring and detection for in situ applications in different industries. This analysis demonstrates the possible applications of low-cost sensors in the corrosion monitoring sector. In addition, this study provides scholars with preferred techniques and the most common microcontrollers, such as Arduino, to overcome the corrosion monitoring difficulties in the construction industry. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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20 pages, 4300 KiB

Open AccessReview

Piezoelectric Materials and Sensors for Structural Health Monitoring: Fundamental Aspects, Current Status, and Future Perspectives

by Min Ju, Zhongshang Dou, Jia-Wang Li, Xuting Qiu, Binglin Shen, Dawei Zhang, Fang-Zhou Yao, Wen Gong and Ke Wang

Sensors 2023, 23(1), 543; https://doi.org/10.3390/s23010543 - 3 Jan 2023

Cited by 73 | Viewed by 13582

Abstract

Structural health monitoring technology can assess the status and integrity of structures in real time by advanced sensors, evaluate the remaining life of structure, and make the maintenance decisions on the structures. Piezoelectric materials, which can yield electrical output in response to mechanical [...] Read more.

Structural health monitoring technology can assess the status and integrity of structures in real time by advanced sensors, evaluate the remaining life of structure, and make the maintenance decisions on the structures. Piezoelectric materials, which can yield electrical output in response to mechanical strain/stress, are at the heart of structural health monitoring. Here, we present an overview of the recent progress in piezoelectric materials and sensors for structural health monitoring. The article commences with a brief introduction of the fundamental physical science of piezoelectric effect. Emphases are placed on the piezoelectric materials engineered by various strategies and the applications of piezoelectric sensors for structural health monitoring. Finally, challenges along with opportunities for future research and development of high-performance piezoelectric materials and sensors for structural health monitoring are highlighted. Full article

(This article belongs to the Special Issue Smart Sensors for Structural Health Monitoring and Nondestructive Evaluation)

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