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Special Issue "Recent Advances of Piezoelectric Transducers and Applications"

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

Deadline for manuscript submissions: 28 February 2019

Special Issue Editors

Guest Editor
Prof. Dr. Gangbing Song

John and Rebecca Moores Professor, Professor of Mechanical Engineering, University of Houston, Houston, TX, USA
Website | E-Mail
Interests: smart materials and structures; structural vibration control; piezoceramics; ultrasonic transducers; structural health monitoring and damage detection
Guest Editor
Dr. Linsheng Huo

School of Civil Engineering, Dalian University of Technology; Dalian 116024, China
Website | E-Mail
Interests: smart structures; damage detection; piezoelectric sensors; strain sensors; embedded sensors; nondestructive testing; structural health monitoring; intelligent civil structures
Guest Editor
Dr. Siu Chun Michael Ho

Research Associate, Department of Mechanical Engineering, University of Houston, Houston, TX, 77204, USA
Website | E-Mail
Interests: embedded sensors; piezoelectric sensors; damage detection; shape sensing; corrosion sensing; fiber opitcal sensors; nondestructive testing; structural health monitoring; intelligent civil structures
Guest Editor
Dr. Qingzhao Kong

Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA
Website | E-Mail
Interests: embedded sensors; piezoelectric sensors; smart structures; damage detection; ultrasonic sensors; nondestructive testing; structural health monitoring; intelligent civil structures

Special Issue Information

Dear Colleagues,

Piezoelectric materials are a class of intelligent materials equipped with the ability to convert mechanical stress into electrical voltage, and vice versa. Their unique properties have contributed to the development of many engineering accomplishments, such as image stabilization technologies, micro-actuators, vibration isolation and cancellation devices, ultrasonic technologies, among a multitude of others. The appearance of piezoelectric transducer is one of the markers of modern engineering, and it is expected that the advantages of piezoelectric materials will continue to be leveraged for the evolution of our engineering capabilities in the foreseeable future.

An emerging area of application for piezoelectric materials is structural health monitoring and piezo-based smart structures, in particular with regards to vibration control and vibration-enabled damage monitoring. This Special Issue aims to gather the latest, state-of-the-art progress in the research of piezoelectric materials in the aforementioned areas.

Potential topics include, but are not limited to:

  • Piezoelectric sensors and transducers: design and application in controls systems, vibration testing, piezoelectric actuators.
  • Piezoelectric based vibration isolation/dampening devices.
  • Application of piezoelectric materials in precision engineering.
  • Structural health monitoring: damage detection and localization.
  • Piezoelectric based acoustic communications and wave generation methods.
  • Piezoelectric based energy harvesting, including for fully embedded monitoring systems.
  • Characterization and modeling of piezoelectric materials.
  • Piezoelectric based damage visualization systems and methods.
  • Micro manipulation using piezoelectric systems.

Prof. Dr. Gangbing Song
Dr. Linsheng Huo
Dr. Siu Chun Michael Ho
Dr. Qingzhao Kong
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 1800 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

  • piezoelectric transducers
  • energy harvesting
  • strain sensing
  • vibration sensing
  • vibration control
  • damage detection
  • structural health monitoring
  • modeling

Published Papers (28 papers)

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Research

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Open AccessArticle Design of a New Stress Wave-Based Pulse Position Modulation (PPM) Communication System with Piezoceramic Transducers
Sensors 2019, 19(3), 558; https://doi.org/10.3390/s19030558
Received: 11 December 2018 / Revised: 22 January 2019 / Accepted: 22 January 2019 / Published: 29 January 2019
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Abstract
Stress wave-based communication has great potential for succeeding in subsea environments where many conventional methods would otherwise face excessive difficulty, and it can benefit logging well by using the drill string as a conduit for stress wave propagation. To achieve stress wave communication, [...] Read more.
Stress wave-based communication has great potential for succeeding in subsea environments where many conventional methods would otherwise face excessive difficulty, and it can benefit logging well by using the drill string as a conduit for stress wave propagation. To achieve stress wave communication, a new stress wave-based pulse position modulation (PPM) communication system is designed and implemented to transmit data through pipeline structures with the help of piezoceramic transducers. This system consists of both hardware and software components. The hardware is composed of a piezoceramic transducer that can generate powerful stress waves travelling along a pipeline, upon touching, and a PPM signal generator that drives the piezoceramic transducer. Once the transducer is in contact with a pipeline surface, the generator integrated with an amplifier is utilized to excite the piezoceramic transducer with a voltage signal that is modulated to encode the information. The resulting vibrations of the transducer generates stress waves that propagate throughout the pipeline. Meanwhile, piezoceramic sensors mounted on the pipeline convert the stress waves to electric signals and the signal can be demodulated. In order to enable the encoding and decoding of information in the stress wave, a PPM-based communication protocol was integrated into the software system. A verification experiment demonstrates the functionality of the developed system for stress wave communication using piezoceramic transducers and the result shows that the data transmission speed of this new communication system can reach 67 bits per second (bps). Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle A Quantitative Approach for the Bone-implant Osseointegration Assessment Based on Ultrasonic Elastic Guided Waves
Sensors 2019, 19(3), 454; https://doi.org/10.3390/s19030454
Received: 14 January 2019 / Revised: 18 January 2019 / Accepted: 20 January 2019 / Published: 22 January 2019
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Abstract
Quantitative and reliable monitoring of osseointegration will help further evaluate the integrity of the orthopaedic construct to promote novel prosthesis design and allow early mobilisation. Quantitative assessment of the degree or the lack of osseointegration is important for the clinical management with the [...] Read more.
Quantitative and reliable monitoring of osseointegration will help further evaluate the integrity of the orthopaedic construct to promote novel prosthesis design and allow early mobilisation. Quantitative assessment of the degree or the lack of osseointegration is important for the clinical management with the introduction of prosthetic implants to amputees. Acousto-ultrasonic wave propagation has been used in structural health monitoring as well as human health monitoring but so far has not extended to osseointegrated implants or prostheses. This paper presents an ultrasonic guided wave approach to assess the osseointegration of a novel implant. This study explores the potential of integrating structural health monitoring concepts into a new osseointegrated implant. The aim is to demonstrate the extension of acousto-ultrasonic techniques, which have been widely reported for the structural health monitoring of engineering structures, to assess the state of osseointegration of a bone and implant. To illustrate this potential, this paper will report on the experimental findings which investigated the unification of an aluminium implant and bone-like geometry surrogate. The core of the test specimen is filled with silicone and wrapped with plasticine to simulate the highly damped cancellous bone and soft tissue, respectively. To simulate the osseointegration process, a 2-h adhesive epoxy is used to bond the surrogate implant and a bone-like structure. A series of piezoelectric elements are bonded onto the surrogate implant to serve as actuators and sensors. The actuating piezoelectric element on an extramedullary strut is excited with a 1 MHz pulse signal. The reception of the ultrasonic wave by the sensing elements located on the adjacent and furthest struts is used to assess the integration of this implant to the parent bone structure. The study shows an Osseointegration Index can be formulated by using engineering and acousto-ultrasonic methods to measure the unification of a bone and implant. This also highlights a potential quantitative evaluation technique regardless of bone-implant geometry and soft tissue damping. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Study on Residual Vibration Suppress of a 3-DOF Flexible Parallel Robot Mechanism
Sensors 2018, 18(12), 4145; https://doi.org/10.3390/s18124145
Received: 24 October 2018 / Revised: 13 November 2018 / Accepted: 22 November 2018 / Published: 26 November 2018
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Abstract
Residual vibration suppression of a 3-DOF flexible parallel robot mechanism is implemented in this paper. Considering the direct and inverse piezoelectric effect of PZT (lead zirconium titanate) material, a general motion equation is established which includes an input equation of PZT actuators and [...] Read more.
Residual vibration suppression of a 3-DOF flexible parallel robot mechanism is implemented in this paper. Considering the direct and inverse piezoelectric effect of PZT (lead zirconium titanate) material, a general motion equation is established which includes an input equation of PZT actuators and an output equation of PZT sensors. A strain and strain rate feedback (SSRF) controller is designed based on the established general motion equation. A numerical simulation is implemented to verify the effectiveness of the SSRF controller in driving the proposed robotic mechanism. The simulation results reveal that the SSRF controller can decrease the elastic vibration displacement of the flexible links rapidly and improve the position accuracy of the moving platform. In the experimental study, one scheme with three passive flexible links is controlled by the SSRF controller at the same time as the performance of the introduced solutions. The experimental results show that the strain and strain rate feedback controller is able to effectively suppress the residual vibration of the 3-DOF flexible parallel robot mechanism. The results of the numerical simulation and experiment are completely consistent. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Self-Sensing CFRP Fabric for Structural Strengthening and Damage Detection of Reinforced Concrete Structures
Sensors 2018, 18(12), 4137; https://doi.org/10.3390/s18124137
Received: 29 October 2018 / Revised: 22 November 2018 / Accepted: 23 November 2018 / Published: 26 November 2018
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Abstract
This paper presents a concept of a Self-sensing Carbon Fiber Reinforced Polymer (SCFRP) system, which integrates the piezoceramic transducers with the common concrete strengthening materials, CFRP fabric. This integration provides the SCFRP fabric with the ability to monitor the structural health condition when [...] Read more.
This paper presents a concept of a Self-sensing Carbon Fiber Reinforced Polymer (SCFRP) system, which integrates the piezoceramic transducers with the common concrete strengthening materials, CFRP fabric. This integration provides the SCFRP fabric with the ability to monitor the structural health condition when the SCFRP fabric is applied on reinforced concrete structures. In order to validate the feasibility of this system, several three-point bending beam (3PBB) specimens were fabricated and tested before and after the specimens were reinforced with the proposed SCFRP fabric. In addition, the specimens with the low (C25) and high (C40) concrete grades were also experimentally investigated to evaluate the reinforced effectiveness of the SCFRP fabric. Finally, the experimental results demonstrate that the proposed SCFRP fabric can significantly improve the bearing capacity of the concrete structures, and provided the reinforced concrete structures with an ability of self-sensing their health condition. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle PZT-Based Ultrasonic Guided Wave Frequency Dispersion Characteristics of Tubular Structures for Different Interfacial Boundaries
Sensors 2018, 18(12), 4111; https://doi.org/10.3390/s18124111
Received: 31 October 2018 / Revised: 20 November 2018 / Accepted: 21 November 2018 / Published: 23 November 2018
Cited by 1 | PDF Full-text (4486 KB) | HTML Full-text | XML Full-text
Abstract
For tubular structures, ultrasonic guided waves (UGWs) which are closely related to interfacial boundary conditions such as gas, liquid and solid materials, are usually used in damage detection. Due to the different phase materials inside tubes, the interfacial boundary (connection) conditions are variable, [...] Read more.
For tubular structures, ultrasonic guided waves (UGWs) which are closely related to interfacial boundary conditions such as gas, liquid and solid materials, are usually used in damage detection. Due to the different phase materials inside tubes, the interfacial boundary (connection) conditions are variable, which has a great influence on the dispersion-related UGW propagation characteristics. However, most UGW-based damage detection methods only consider the pipeline structures as hollow tubes, ignoring the interfacial boundary condition influences on the UGW propagation. Based on the UGW theory, this paper aims to propose a novel method for describing the UGW propagation characteristics for different interfaces, and lay a foundation for the UGW-based tubular structure damage detection. Based on the Navier’s equation of motion and combined with interfacial boundary conditions and coordinate conditions, the dispersion equations for a hollow steel tube, a tube filled with liquid, and a concrete filled steel tube (CFST) were established, respectively. Under the given conditions of both materials and geometric parameters, the transcendental dispersion equations were established and solved by using a numerical method. The UGW propagation characteristics in different interfaces were classified and discussed, and the dispersion curves of both group and phase velocities are drawn. To validate the efficiency of theoretical and numerical results, three kinds of model tubular structure experiments filled in air (hollow), water and concrete, respectively, were performed based on lead zirconate titanate (PZT) transducer UGWs. The results showed that the UGWs propagation in different interfaces has the dispersion and multi-modes characters, which are not only related to the product of frequency and thickness, but also to the internal dielectric material parameters and interfacial boundary conditions. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Validation of Finite Element Model by Smart Aggregate-Based Stress Monitoring
Sensors 2018, 18(11), 4062; https://doi.org/10.3390/s18114062
Received: 24 September 2018 / Revised: 6 November 2018 / Accepted: 15 November 2018 / Published: 21 November 2018
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Abstract
Concrete compressive strength is an important parameter of material properties for assessing seismic performance of reinforced concrete (RC) structures, which has a certain level of uncertainty due to its inherent variability. In this paper, the method of concrete strength validation of finite element [...] Read more.
Concrete compressive strength is an important parameter of material properties for assessing seismic performance of reinforced concrete (RC) structures, which has a certain level of uncertainty due to its inherent variability. In this paper, the method of concrete strength validation of finite element model using smart aggregate (SA)-based stress monitoring is proposed. The FE model was established using Open System for Earthquake Engineering Simulation (OpenSEES) platform. The concrete strengths obtained from the material test, peak stress of SA, and estimated concrete strength based on SA stress were employed in FE models. The lateral displacement monitored by Liner variable differential transformer and vertical axial load monitored by load cell in the experiment are applied in the model. By comparing the global response (i.e., lateral reaction force and hysteretic loop), local response (i.e., concrete stress, rebar strain, and cross-section moment) and corresponding root-mean-square error obtained from experiment and numerical analysis, the capabilities of validation of FE model using SA-based stress monitoring method were demonstrated. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Contact Force Measurement in an Operational Thrust Bearing using PVDF Film at the Blade and Pad Passing Frequencies
Sensors 2018, 18(11), 3956; https://doi.org/10.3390/s18113956
Received: 3 October 2018 / Revised: 1 November 2018 / Accepted: 10 November 2018 / Published: 15 November 2018
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Abstract
A major contributor to longitudinal vibration in marine propulsion systems is propeller induced excitation. This constitutes a key source of underwater acoustical radiation through excitation of the hull. Understanding this hydrodynamic force at the interface of the thrust bearing is important in order [...] Read more.
A major contributor to longitudinal vibration in marine propulsion systems is propeller induced excitation. This constitutes a key source of underwater acoustical radiation through excitation of the hull. Understanding this hydrodynamic force at the interface of the thrust bearing is important in order to develop an accurate vibrational model of the propulsion system and in determining potential control mechanisms. In order to investigate the thrust force during operation of a propulsion system, Polyvinylidene Fluoride (PVDF) was embedded into the stationery collar inside a custom thrust bearing in a scaled model of a typical propulsion system. The number of blades of the propeller and its rotational speed were altered to obtain an understanding of the characteristic vibrations of the shaft propulsion system. The rig comprised of the propeller, shaft, journal bearings and a thrust bearing. A two and three blade propeller and a four, five and six pad bearing were tested. A strain gauge and accelerometer were used to infer the propeller force and enable comparison with the PVDF signals. As a result of the asymmetrical flow around the propeller, the blade passing frequencies (BPF) are clearly observed. This frequency contribution was present at all speeds tested. The PVDF signal also showed significant pad passing frequency (PPF) and BPF and modulation of both. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle A POSHE-Based Optimum Clip-Limit Contrast Enhancement Method for Ultrasonic Logging Images
Sensors 2018, 18(11), 3954; https://doi.org/10.3390/s18113954
Received: 10 October 2018 / Revised: 5 November 2018 / Accepted: 12 November 2018 / Published: 15 November 2018
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Abstract
Enabled by piezoceramic transducers, ultrasonic logging images often suffer from low contrast and indistinct local details, which makes it difficult to analyze and interpret geologic features in the images. In this work, we propose a novel partially overlapped sub-block histogram-equalization (POSHE)-based optimum clip-limit [...] Read more.
Enabled by piezoceramic transducers, ultrasonic logging images often suffer from low contrast and indistinct local details, which makes it difficult to analyze and interpret geologic features in the images. In this work, we propose a novel partially overlapped sub-block histogram-equalization (POSHE)-based optimum clip-limit contrast enhancement (POSHEOC) method to highlight the local details hidden in ultrasonic well logging images obtained through piezoceramic transducers. The proposed algorithm introduces the idea of contrast-limited enhancement to modify the cumulative distribution functions of the POSHE and build a new quality evaluation index considering the effects of the mean gradient and mean structural similarity. The new index is designed to obtain the optimal clip-limit value for histogram equalization of the sub-block. It makes the choice of the optimal clip-limit automatically according to the input image. Experimental results based on visual perceptual evaluation and quantitative measures demonstrate that the proposed method yields better quality in terms of enhancing the contrast, emphasizing the local details while preserving the brightness and restricting the excessive enhancement compared with the other seven histogram equalization-based techniques from the literature. This study provides a feasible and effective method to enhance ultrasonic logging images obtained through piezoceramic transducers and is significant for the interpretation of actual ultrasonic logging data. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Ultrasonic Sensing and Actuation in Laminate Structures Using Bondline-Embedded d35 Piezoelectric Sensors
Sensors 2018, 18(11), 3885; https://doi.org/10.3390/s18113885
Received: 18 October 2018 / Revised: 4 November 2018 / Accepted: 7 November 2018 / Published: 11 November 2018
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Abstract
Ultrasonic systems employing embedded piezoelectric transducers have seen increased interest in recent years. The ability to sense, actuate, and analyze the wave propagation modes in engineering structures has been fundamental to the advancement of ultrasonic structural health monitoring (SHM). This paper presents a [...] Read more.
Ultrasonic systems employing embedded piezoelectric transducers have seen increased interest in recent years. The ability to sense, actuate, and analyze the wave propagation modes in engineering structures has been fundamental to the advancement of ultrasonic structural health monitoring (SHM). This paper presents a study into the sensing and actuation properties of shear-mode (d35) piezoelectric transducers made of lead zirconate titanate (PZT) that are internally embedded in the bondline of laminate structures. The manuscript presents analytical analysis, finite element simulation, and experimental validation building from an individual piezoelectric element to a full laminate structure. The validated model was then used to perform a parametric study into the effects of d35 PZT transducer size on the strength of actuation and sensing output signal. The selectivity of d35 PZT sensors was also investigated by generating multiple wave modes in the laminate structure and inspecting the output signals. The d35 PZT sensors were found to selectively detect only certain modes of the wave propagation providing a fundamental hardware filter that could be employed to simplify signal analysis and processing. The results of this study indicate that d35 PZTs embedded in the bondline have multiple properties that can potentially be employed for ultrasonic SHM. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Loosening Monitoring of a Threaded Pipe Connection Using the Electro-Mechanical Impedance Technique—Experimental and Numerical Studies
Sensors 2018, 18(11), 3699; https://doi.org/10.3390/s18113699
Received: 7 September 2018 / Revised: 28 October 2018 / Accepted: 29 October 2018 / Published: 30 October 2018
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Abstract
Threaded connections are the most common pipe fittings used in oil and gas transportation systems. Due to external vibrations, cyclic loads, and pollution, the fitting parts may start getting loose, which could result in pipeline leaks and other environmental disasters. It is of [...] Read more.
Threaded connections are the most common pipe fittings used in oil and gas transportation systems. Due to external vibrations, cyclic loads, and pollution, the fitting parts may start getting loose, which could result in pipeline leaks and other environmental disasters. It is of great significance to develop a reliable technique that could provide real-time monitoring of the looseness of pipeline fittings. In this paper, a piezoceramic-based active sensing method combined with the electro-mechanical impedance (EMI) technique was developed to monitor the health condition of threaded pipe connections in real time. Two pipe segments coupled with a threaded coupling fitting were assembled in the laboratory, and a lead zirconate titanate (PZT) patch was surface bonded onto the coupling part. In the experiment, the PZT impedance signatures were measured at each simulated loosening condition. A root-mean-square deviation (RMSD) method was employed to build a looseness index from the measured impedance signatures. To verify the effectiveness of the developed EMI technique, the experimental results were compared with those computed from a numerical simulation. The good agreement from experimental and numerical results highlights that the developed piezoceramic-based EMI technique has great potential for determining early looseness, as well as for monitoring the health status of the pipeline fitting during its service life. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Electro-Mechanical Impedance (EMI) Based Interlayer Slide Detection Using Piezoceramic Smart Aggregates—A Feasibility Study
Sensors 2018, 18(10), 3524; https://doi.org/10.3390/s18103524
Received: 17 September 2018 / Revised: 15 October 2018 / Accepted: 16 October 2018 / Published: 18 October 2018
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Abstract
Interlayer slide damage is one of the main causes of landslide hazard, inflicting huge economic losses and casualties. It is urgent to accurately detect the initiation and development of the interlayer slide damage in real time. In this paper, a study on the [...] Read more.
Interlayer slide damage is one of the main causes of landslide hazard, inflicting huge economic losses and casualties. It is urgent to accurately detect the initiation and development of the interlayer slide damage in real time. In this paper, a study on the feasibility of using the electro-mechanical impedance (EMI) technique to detect the interlayer slide damage was presented. The main purpose of this paper is to investigate the application of the EMI technique for interlayer slide detection using piezoceramic smart aggregates (SAs). In the experimental study, three small landslide specimens with a weak interlayer in the middle were fabricated. For each specimen, three piezoceramic SAs were post-embedded at specific positions, which were located above the weak interlayer inside the structure. The specimens were subjected to a compressive test to initiate an interlayer slide along the weak layer. The whole loading process was monitored with a precision impedance analyzer by measuring the admittance (reciprocal of impedance) of the SAs over time. The statistic metrics, including root mean square deviation (RMSD) and mean absolute percentage deviation (MAPD), were introduced to quantify the variations in admittance signatures due to interlayer slide damage. It was found that the admittance signatures and statistic metrics were sensitive to the interlayer slide damage. The experimental results verify the feasibility and practicality of using EMI technique to detect the interlayer slide. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Development of a Multiwavelength Visible-Range-Supported Opto–Ultrasound Instrument Using a Light-Emitting Diode and Ultrasound Transducer
Sensors 2018, 18(10), 3324; https://doi.org/10.3390/s18103324
Received: 19 September 2018 / Revised: 30 September 2018 / Accepted: 30 September 2018 / Published: 3 October 2018
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Abstract
A new multiwavelength visible-range-supported opto–ultrasound instrument using a light-emitting diode and ultrasound transducer was developed in order to produce multiwavelength visible light with minimized color aberration errors, and detect ultrasound signals emitted from the target. In the instrument, the developed optical systems can [...] Read more.
A new multiwavelength visible-range-supported opto–ultrasound instrument using a light-emitting diode and ultrasound transducer was developed in order to produce multiwavelength visible light with minimized color aberration errors, and detect ultrasound signals emitted from the target. In the instrument, the developed optical systems can provide multiwavelength optical transmission with low optical aberration within 10-cm ranges that are reasonably flat in the modulation transfer function at spatial frequencies of 20 and 40 lp/mm, except at the end of the diagonal edge of the samples. To assess the instrument capability, we performed pulse–echo responses with Thunnus obesus eye samples. Focused red, green, blue and white light rays from an integrated red, green and blue LED source were produced, and echo signal amplitudes of 33.53, 34.92, 38.74 and 82.54 mV, respectively, were detected from the Thunnus obesus eye samples by a 10-MHz focused ultrasound transducer. The center frequencies of the echo signal when producing red, green, blue and white LED light in the instrument were 9.02, 9.05, 9.21 and 8.81 MHz, respectively. From these tests, we verify that this instrument can combine red, green and blue LED light to cover different wavelengths in the visible-light range and detect reasonable echo amplitudes from the samples. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Study on the Magnetic-machine Coupling Characteristics of Giant Magnetostrictive Actuator Based on the Free Energy Hysteresis Characteristics
Sensors 2018, 18(9), 3070; https://doi.org/10.3390/s18093070
Received: 29 July 2018 / Revised: 6 September 2018 / Accepted: 10 September 2018 / Published: 12 September 2018
Cited by 1 | PDF Full-text (3311 KB) | HTML Full-text | XML Full-text
Abstract
A giant magnetostrictive actuator presents advantages such as large strain, high precision, and quick response. It is a hotly debated research topic in the field of micro drivers; however, the nonlinear intrinsic relationship between its output and input signals make it difficult to [...] Read more.
A giant magnetostrictive actuator presents advantages such as large strain, high precision, and quick response. It is a hotly debated research topic in the field of micro drivers; however, the nonlinear intrinsic relationship between its output and input signals make it difficult to construct its nonlinear eigen model in the process of its practical application. Therefore, the motivation of this paper is to study the nonlinear magnetic–mechanical coupling characteristics of the giant magnetostrictive actuator, which is driven by free energy hysteresis characteristics. The nonlinear magnetic–mechanical coupling model under the weak form solution is deduced from the basic electromagnetic and mechanical theories, based on the distribution law of the axial magnetic field simulation, carried out to analyze the output displacement characteristics of the giant magnetostrictive actuator under preload. Experimental characterization of the device is also studied in the built experiment setup. Research results show that the experimental results coincide well with the simulation results, which show that the designed magnetic circuit for the giant magnetostrictive actuator is correct, and the coupling model of magnetic and machine of the giant magnetostrictive actuator based on the free energy hysteresis characteristics is reasonable. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Equivalent Circuit Modeling for a Valveless Piezoelectric Pump
Sensors 2018, 18(9), 2881; https://doi.org/10.3390/s18092881
Received: 30 June 2018 / Revised: 9 August 2018 / Accepted: 16 August 2018 / Published: 31 August 2018
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Abstract
Various kinds of the models had been proposed to explain the relationship between the performance and the structural parameters of valveless piezoelectric pumps, so as to evaluate the functional performance such devices. Among the models, the equivalent circuit model, which converts the multi-field [...] Read more.
Various kinds of the models had been proposed to explain the relationship between the performance and the structural parameters of valveless piezoelectric pumps, so as to evaluate the functional performance such devices. Among the models, the equivalent circuit model, which converts the multi-field problem of a valveless piezoelectric pump system into a simple circuit problem, is the most simple and clear one. Therefore, the proposed structure and working principle of the valveless piezoelectric pump with multistage Y-shape treelike bifurcate tubes are analyzed; then, the equivalent circuit model of the valveless piezoelectric pump is established based on the working principles of this pump and liquid-electric analogy theory. Finally, an experimental study of the pump is carried out, with a comparative analysis of the experimental results and the simulation results of the generated equivalent circuit. The experimental results show that with a driving voltage of 100 V and frequency of 6 Hz, the maximum flow rate of the valveless piezoelectric pump is 1.16 mL/min. Meanwhile, the output current of equivalent circuit also reaches its peak at the frequency of 6 Hz, therefore, indicating a good predictive ability of this model in calculating the maximum output flow rate and best working frequency of valveless piezoelectric pumps. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Evaluation of the Effect of Fly Ash on Hydration Characterization in Self-Compacting Concrete (SCC) at Very Early Ages Using Piezoceramic Transducers
Sensors 2018, 18(8), 2489; https://doi.org/10.3390/s18082489
Received: 22 May 2018 / Revised: 12 July 2018 / Accepted: 25 July 2018 / Published: 1 August 2018
Cited by 3 | PDF Full-text (11747 KB) | HTML Full-text | XML Full-text
Abstract
Nowadays, the industrial waste, Fly Ash (FA), as a mineral admixture or a replacement of cement for the production of self-compacting concrete (SCC) has been increasingly used, because of its benefits in enhancing both fresh and long-term concrete properties and in promoting environmental-friendly [...] Read more.
Nowadays, the industrial waste, Fly Ash (FA), as a mineral admixture or a replacement of cement for the production of self-compacting concrete (SCC) has been increasingly used, because of its benefits in enhancing both fresh and long-term concrete properties and in promoting environmental-friendly construction. In this study, the conventional cement was replaced by FA at different rates (0%, 20%, 40%, 60% of the cement mass) for the SCC mixtures. The early-age (0–24 h) SCC hydration, which is a complicated chemical reaction in pozzolanic behavior, was characterized by using a pair of piezoceramic Smart Aggregates (SAs). One SA works as an actuator and the other works as a sensor. A sweep sine signal from 100 Hz to100 kHz was used as the excitation signal, which is helpful to understand the quantitative influence of fly ash on the kinetics of SCC hydration. During the hydration reaction, the received electrical signal was continuously detected by the sensor. The experimental results showed that increasing the volume of fly ash resulted in longer pozzolanic reaction time in SCCs, which successfully reveals the effect of fly ash volume on the hydration behavior in early age (0–24 h) hydration. In order to quantitatively evaluate the hydration in the 0–24 h, based on the wavelet packet energy analysis, the hydration completion index (HCI) and normalized hydration completion index (NHCI) were defined. The experimental results showed that the NHCI can clearly reveal the hydration completion progress during the early hydration age (0–24 h). To validate the accuracy of the test results based on SAs, a series of mechanical tests for penetration resistance of SCCs with different volumes of fly ash were carried out. The results predicted by the signal based on SAs gave reasonable agreement with the test results of penetration resistance. It can be concluded that a successful investigation of the influence of fly ash on early-age SCC hydration response can be achieved based on the analysis of the received electrical signal using the proposed method and the important hydration characteristics, such as initial and final setting time, and can be approximately predicted by NHCI values. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Experimental Study on the Performance of Hydraulic Vibration Assisted Broaching (HVAB) Based on Piezoelectric Sensors
Sensors 2018, 18(8), 2417; https://doi.org/10.3390/s18082417
Received: 13 June 2018 / Revised: 13 July 2018 / Accepted: 15 July 2018 / Published: 25 July 2018
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Abstract
In order to improve the keyway broaching process and verify the feasibility of vibration-assisted broaching process, an experimental study on a novel hydraulic vibration assisted broaching (HVAB) system with double-valve electro-hydraulic exciter (DVEHE) is proposed in this paper. The performances of HVAB at [...] Read more.
In order to improve the keyway broaching process and verify the feasibility of vibration-assisted broaching process, an experimental study on a novel hydraulic vibration assisted broaching (HVAB) system with double-valve electro-hydraulic exciter (DVEHE) is proposed in this paper. The performances of HVAB at different excitation frequencies were compared from three aspects: (a) the cutting force under the different vibration frequencies, (b) the surface roughness of the workpiece, and (c) the flank face wear of the tool. For precision on-line measurement of larger broaching forces, four piezoelectric sensors were fixed on the broaching machine. The experimental results show that HVAB can effectively improve the performance of the broaching process, approximately reduce the broaching force by as much as 9.7% compared to conventional broaching (CB) and improve the surface quality of workpiece. Some explanations are offered to support the observations. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Experimental Verification of the Pumping Effect Caused by the Micro-Tapered Hole in a Piezoelectric Atomizer
Sensors 2018, 18(7), 2311; https://doi.org/10.3390/s18072311
Received: 20 June 2018 / Revised: 11 July 2018 / Accepted: 15 July 2018 / Published: 17 July 2018
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Abstract
In this study, we examined the use of a dynamic micro-tapered hole as a micro-scale tapered flow tube valveless piezoelectric pump. Firstly, we obtained photographs of a micro-tapered hole by using an environmental scanning electron microscope (ESEM). Then, we explained the pump effect [...] Read more.
In this study, we examined the use of a dynamic micro-tapered hole as a micro-scale tapered flow tube valveless piezoelectric pump. Firstly, we obtained photographs of a micro-tapered hole by using an environmental scanning electron microscope (ESEM). Then, we explained the pump effect of the micro-tapered hole, and derived the atomization rate equation. Furthermore, we reported an atomization rate measurement experiment that eliminated the atomization caused by a pressure increase, and demonstrated that a change in the volume of a micro-tapered hole could produce atomization. The experimental results indicate that, under the same voltage, the forward atomization rate is much higher than the reverse atomization rate and that the atomization rate increases with the micro-tapered hole volume. The experimental results show that the atomization of the micro-tapered aperture atomizer is caused by its pumping effect. Moreover, the flow resistance and volume of the micro-tapered hole can affect the atomization rate. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Loosening Monitoring of the Threaded Pipe Connection Using Time Reversal Technique and Piezoceramic Transducers
Sensors 2018, 18(7), 2280; https://doi.org/10.3390/s18072280
Received: 16 June 2018 / Revised: 12 July 2018 / Accepted: 12 July 2018 / Published: 14 July 2018
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Abstract
Threaded pipe connections are commonly used in the oil and gas industry in particular to connect casting strings, drill pipe strings, production and transportation risers, and pipelines. As the most critical components in the entire chain, maintaining a sealed and secure connection while [...] Read more.
Threaded pipe connections are commonly used in the oil and gas industry in particular to connect casting strings, drill pipe strings, production and transportation risers, and pipelines. As the most critical components in the entire chain, maintaining a sealed and secure connection while being subjected to environmental loads and pollution is very important and necessary to reduce potential leakage risk and guarantee the safety of the entire chain. In this paper, an effective approach using time reversal technique and lead zirconate titanate (PZT) transducer was developed to monitor the looseness of the threaded pipe connection. Two threaded pipeline segments connected with a metal coupling were assembled to simulate the threaded connection in the pipeline system. Two PZT patches were mounted on the surface of one pipeline segment and the pipe coupling, respectively. By loosening the threaded connection with different rotation angles, several looseness scenarios were experimentally investigated. For each looseness condition, the developed time reversal-based approach was performed and the corresponding response signal was acquired and analyzed. The experimental results demonstrate that the peak value of the focused signal detected by the PZT sensor decreases with the increase of the looseness degree. The entire test conducted from tightened connection to loosened connection was repeated eight times to validate the repeatability of the developed method and the consistency of the detection results. In addition, the reliability of the developed method was studied by involving high disturbances when the signal was measured. All the test results show that the developed method has a great potential to be employed in practical applications for monitoring the looseness condition of the threaded pipe connection, especially in an environment with severe noises and disturbances. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Debonding Detection in Hidden Frame Supported Glass Curtain Walls Using the Nonlinear Ultrasonic Modulation Method with Piezoceramic Transducers
Sensors 2018, 18(7), 2094; https://doi.org/10.3390/s18072094
Received: 18 May 2018 / Revised: 26 June 2018 / Accepted: 26 June 2018 / Published: 29 June 2018
Cited by 6 | PDF Full-text (7302 KB) | HTML Full-text | XML Full-text
Abstract
Debonding defects are common and they are the main reason for the failure of hidden frame supported glass curtain walls, which are widely used as an external enclosure and decorative structure. In this paper, a debonding detection method for hidden frame supported glass [...] Read more.
Debonding defects are common and they are the main reason for the failure of hidden frame supported glass curtain walls, which are widely used as an external enclosure and decorative structure. In this paper, a debonding detection method for hidden frame supported glass curtain walls is developed based on nonlinear ultrasonic modulation and piezoceramic transducers. First, the excitation frequency was determined according to the response characteristics. Then, empirical mode decomposition (EMD) was applied to extract the feature components. After discrete Fourier transform (DFT), the nonlinear coefficients were calculated to evaluate the debonding defect. Finally, the experimental setup was established and a series of experiments were carried out to verify the feasibility and effectiveness of the nonlinear ultrasonic modulation method. The nonlinear harmonics detection method was also investigated and it was compared with the nonlinear ultrasonic modulation method. The detection effect at different temperatures and impact were studied. The results showed that the nonlinear coefficient increases with the debonding length. The mean squared error (MSE) of the nonlinear ultrasonic modulation method was improved by 41% compared with the nonlinear harmonics method. The nonlinear ultrasonic modulation method can successfully detect debonding defects in hidden frame supported glass curtain walls at different temperatures and impact. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessFeature PaperArticle Influence of Axial Load on Electromechanical Impedance (EMI) of Embedded Piezoceramic Transducers in Steel Fiber Concrete
Sensors 2018, 18(6), 1782; https://doi.org/10.3390/s18061782
Received: 15 March 2018 / Revised: 27 May 2018 / Accepted: 29 May 2018 / Published: 1 June 2018
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Abstract
With the advantages of high tensile, bending, and shear strength, steel fiber concrete structures have been widely used in civil engineering. The health monitoring of concrete structures, including steel fiber concrete structures, receives increasing attention, and the Electromechanical Impedance (EMI)-based method is commonly [...] Read more.
With the advantages of high tensile, bending, and shear strength, steel fiber concrete structures have been widely used in civil engineering. The health monitoring of concrete structures, including steel fiber concrete structures, receives increasing attention, and the Electromechanical Impedance (EMI)-based method is commonly used. Structures are often subject to changing axial load and ignoring the effect of axial forces may introduce error to Structural Health Monitoring (SHM), including the EMI-based method. However, many of the concrete structure monitoring algorithms do not consider the effects of axial loading. To investigate the influence of axial load on the EMI of a steel fiber concrete structure, concrete specimens with different steel fiber content (0, 30, 60, 90, 120) (kg/m3) were casted and the Lead Zirconate Titanate (PZT)-based Smart Aggregate (SA) was used as the EMI sensor. During tests, the step-by-step loading procedure was applied on different steel fiber content specimens, and the electromechanical impedance values were measured. The Normalized root-mean-square deviation Index (NI) was developed to analyze the EMI information and evaluate the test results. The results show that the normalized root-mean-square deviation index increases with the increase of the axial load, which clearly demonstrates the influence of axial load on the EMI values for steel fiber concrete and this influence should be considered during a monitoring or damage detection procedure if the axial load changes. In addition, testing results clearly reveal that the steel fiber content, often at low mass and volume percentage, has no obvious influence on the PZT’s EMI values. Furthermore, experiments to test the repeatability of the proposed method were conducted. The repeating test results show that the EMI-based indices are repeatable and there is a great linearity between the NI and the applied loading. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Health Monitoring of Bolted Spherical Joint Connection Based on Active Sensing Technique Using Piezoceramic Transducers
Sensors 2018, 18(6), 1727; https://doi.org/10.3390/s18061727
Received: 19 April 2018 / Revised: 19 May 2018 / Accepted: 23 May 2018 / Published: 28 May 2018
Cited by 7 | PDF Full-text (8471 KB) | HTML Full-text | XML Full-text
Abstract
Bolted spherical joints are widely used to form space steel structures. The stiffness and load capacity of the structures are affected by the looseness of bolted spherical joint connections in the structures. The looseness of the connections, which can be caused by fabrication [...] Read more.
Bolted spherical joints are widely used to form space steel structures. The stiffness and load capacity of the structures are affected by the looseness of bolted spherical joint connections in the structures. The looseness of the connections, which can be caused by fabrication error, low modeling accuracy, and “false twist” in the installation process, may negatively impact the load capacity of the structure and even lead to severe accidents. Furthermore, it is difficult to detect bolted spherical joint connection looseness from the outside since the bolts connect spheres with rods together from the inside. Active sensing methods are proposed in this paper to monitor the tightness status of the bolted spherical connection using piezoceramic transducers. A triangle-on-triangle offset grid composed of bolted spherical joints and steel tube bars was fabricated as the specimen and was used to validate the active sensing methods. Lead Zirconate Titanate (PZT) patches were used as sensors and actuators to monitor the bolted spherical joint tightness status. One PZT patch mounted on the central bolted sphere at the upper chord was used as an actuator to generate a stress wave. Another PZT patch mounted on the bar was used as a sensor to detect the propagated waves through the bolted spherical connection. The looseness of the connection can impact the energy of the stress wave propagated through the connection. The wavelet packet analysis and time reversal (TR) method were used to quantify the energy of the transmitted signal between the PZT patches by which the tightness status of the connection can be detected. In order to verify the effectiveness, repeatability, and consistency of the proposed methods, the experiments were repeated six times in different bolted spherical connection positions. The experimental results showed that the wavelet packet analysis and TR method are effective in detecting the tightness status of the connections. The proposed active monitoring method using PZT transducers can monitor the tightness levels of bolted spherical joint connections efficiently and shows its potential to guarantee the safety of space steel structures in construction and service. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle A PVDF-Based Sensor for Internal Stress Monitoring of a Concrete-Filled Steel Tubular (CFST) Column Subject to Impact Loads
Sensors 2018, 18(6), 1682; https://doi.org/10.3390/s18061682
Received: 26 March 2018 / Revised: 15 May 2018 / Accepted: 17 May 2018 / Published: 23 May 2018
Cited by 5 | PDF Full-text (5040 KB) | HTML Full-text | XML Full-text
Abstract
Impact loads can have major adverse effects on the safety of civil engineering structures, such as concrete-filled steel tubular (CFST) columns. The study of mechanical behavior and stress analysis of CFST columns under impact loads is very important to ensure their safety against [...] Read more.
Impact loads can have major adverse effects on the safety of civil engineering structures, such as concrete-filled steel tubular (CFST) columns. The study of mechanical behavior and stress analysis of CFST columns under impact loads is very important to ensure their safety against such loads. At present, the internal stress monitoring of the concrete cores CFST columns under impact loads is still a very challenging subject. In this paper, a PVDF (Polyvinylidene Fluoride) piezoelectric smart sensor was developed and successfully applied to the monitoring of the internal stress of the concrete core of a CFST column under impact loads. The smart sensor consists of a PVDF piezoelectric film sandwiched between two thin steel plates through epoxy. The protection not only prevents the PVDF film from impact damages but also ensures insulation and waterproofing. The smart sensors were embedded into the circular concrete-filled steel tube specimen during concrete pouring. The specimen was tested against impact loads, and testing data were collected. The time history of the stress obtained from the PVDF smart sensor revealed the evolution of core concrete internal stress under impact loads when compared with the impact force–time curve of the hammer. Nonlinear finite element simulations of the impact process were also carried out. The results of FEM simulations had good agreement with the test results. The results showed that the proposed PVDF piezoelectric smart sensors can effectively monitor the internal stress of concrete-filled steel tubular columns under impact loads. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessFeature PaperArticle Damage Evaluation of Concrete Column under Impact Load Using a Piezoelectric-Based EMI Technique
Sensors 2018, 18(5), 1591; https://doi.org/10.3390/s18051591
Received: 20 March 2018 / Revised: 8 May 2018 / Accepted: 14 May 2018 / Published: 17 May 2018
Cited by 9 | PDF Full-text (4809 KB) | HTML Full-text | XML Full-text
Abstract
One of the major causes of damage to column-supported concrete structures, such as bridges and highways, are collisions from moving vehicles, such as cars and ships. It is essential to quantify the collision damage of the column so that appropriate actions can be [...] Read more.
One of the major causes of damage to column-supported concrete structures, such as bridges and highways, are collisions from moving vehicles, such as cars and ships. It is essential to quantify the collision damage of the column so that appropriate actions can be taken to prevent catastrophic events. A widely used method to assess structural damage is through the root-mean-square deviation (RMSD) damage index established by the collected data; however, the RMSD index does not truly provide quantitative information about the structure. Conversely, the damage volume ratio that can only be obtained via simulation provides better detail about the level of damage in a structure. Furthermore, as simulation can also provide the RMSD index relating to that particular damage volume ratio, the empirically obtained RMSD index can thus be related to the structural damage degree through comparison of the empirically obtained RMSD index to numerically-obtained RMSD. Thus, this paper presents a novel method in which the impact-induced damage to a structure is simulated in order to obtain the relationship between the damage volume ratio to the RMSD index, and the relationship can be used to predict the true damage degree by comparison to the empirical RMSD index. In this paper, the collision damage of a bridge column by moving vehicles was simulated by using a concrete beam model subjected to continuous impact loadings by a freefalling steel ball. The variation in admittance signals measured by the surface attached lead zirconate titanate (PZT) patches was used to establish the RMSD index. The results demonstrate that the RMSD index and the damage ratio of concrete have a linear relationship for the particular simulation model. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle A Feasibility Study on Timber Damage Detection Using Piezoceramic-Transducer-Enabled Active Sensing
Sensors 2018, 18(5), 1563; https://doi.org/10.3390/s18051563
Received: 12 April 2018 / Revised: 10 May 2018 / Accepted: 12 May 2018 / Published: 15 May 2018
Cited by 4 | PDF Full-text (5905 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, piezoelectric-based transducers and technologies have made significant progress towards structural health monitoring and damage evaluation for various metal and concrete structures. Timber is still commonly used as a construction material in practical engineering; however, there is a lack of research [...] Read more.
In recent years, piezoelectric-based transducers and technologies have made significant progress towards structural health monitoring and damage evaluation for various metal and concrete structures. Timber is still commonly used as a construction material in practical engineering; however, there is a lack of research on the health monitoring of timber-based structures using piezoelectric-based transducers and methods. This paper conducts a feasibility study on timber damage detection using surface-mounted piezoelectric patches, which enable the stress-wave-based active sensing approach. Typical damage modes in timber frame structures, such as surface cracks and holes, were investigated in this study. In the active sensing approach, one piezoceramic transducer is used as an actuator to generate stress waves, which propagate along the surface of the timber structure, and other piezoceramic transducers function as sensors to detect the propagating stress waves. Defects, such as a crack or a hole, induce additional attenuation to the propagating stress wave. Based on this attenuation, the proposed method can detect the defects using the wavelet-packet-based damage index, demonstrating its implementation potential for real-time timber damage detection. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle A Novel Nonlinear Piezoelectric Energy Harvesting System Based on Linear-Element Coupling: Design, Modeling and Dynamic Analysis
Sensors 2018, 18(5), 1492; https://doi.org/10.3390/s18051492
Received: 28 March 2018 / Revised: 27 April 2018 / Accepted: 3 May 2018 / Published: 9 May 2018
Cited by 2 | PDF Full-text (7633 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a novel nonlinear piezoelectric energy harvesting system which consists of linear piezoelectric energy harvesters connected by linear springs. In principle, the presented nonlinear system can improve broadband energy harvesting efficiency where magnets are forbidden. The linear spring inevitably produces the [...] Read more.
This paper presents a novel nonlinear piezoelectric energy harvesting system which consists of linear piezoelectric energy harvesters connected by linear springs. In principle, the presented nonlinear system can improve broadband energy harvesting efficiency where magnets are forbidden. The linear spring inevitably produces the nonlinear spring force on the connected harvesters, because of the geometrical relationship and the time-varying relative displacement between two adjacent harvesters. Therefore, the presented nonlinear system has strong nonlinear characteristics. A theoretical model of the presented nonlinear system is deduced, based on Euler-Bernoulli beam theory, Kirchhoff’s law, piezoelectric theory and the relevant geometrical relationship. The energy harvesting enhancement of the presented nonlinear system (when n = 2, 3) is numerically verified by comparing with its linear counterparts. In the case study, the output power area of the presented nonlinear system with two and three energy harvesters is 268.8% and 339.8% of their linear counterparts, respectively. In addition, the nonlinear dynamic response characteristics are analyzed via bifurcation diagrams, Poincare maps of the phase trajectory, and the spectrum of the output voltage. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessArticle Development and Hybrid Position/Force Control of a Dual-Drive Macro-Fiber-Composite Microgripper
Sensors 2018, 18(4), 1301; https://doi.org/10.3390/s18041301
Received: 1 April 2018 / Revised: 17 April 2018 / Accepted: 20 April 2018 / Published: 23 April 2018
Cited by 2 | PDF Full-text (7147 KB) | HTML Full-text | XML Full-text
Abstract
This paper reports on the development, implementation and hybrid control of a new micro-fiber-composite microgripper with synchronous position and force control capabilities. In particular, the micro-fiber-composite actuator was composed of rectangular piezoelectric fibers covered by interdigitated electrodes and embedded in structural epoxy. Thus, [...] Read more.
This paper reports on the development, implementation and hybrid control of a new micro-fiber-composite microgripper with synchronous position and force control capabilities. In particular, the micro-fiber-composite actuator was composed of rectangular piezoelectric fibers covered by interdigitated electrodes and embedded in structural epoxy. Thus, the micro-fiber-composite microgripper had a larger displacement-volume ratio (i.e., the ratio of the output displacement to the volume of the microgripper) than that of a traditional piezoelectric one. Moreover, to regulate both the gripper position and the gripping force simultaneously, a hybrid position/force control scheme using fuzzy sliding mode control and the proportional-integral controller was developed. In particular, the fuzzy sliding mode control was used to achieve the precision position control under the influence of the system disturbances and uncertainties, and the proportional-integral controller was used to guarantee the force control accuracy of the microgripper. A series of experimental investigations was performed to verify the feasibility of the developed microgripper and the control scheme. The experimental results validated the effectiveness of the designed microgripper and hybrid control scheme. The developed microgripper was capable of precision and multiscale micromanipulation tasks. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessReview Advances in the Structural Health Monitoring of Bridges Using Piezoelectric Transducers
Sensors 2018, 18(12), 4312; https://doi.org/10.3390/s18124312
Received: 30 October 2018 / Revised: 26 November 2018 / Accepted: 2 December 2018 / Published: 7 December 2018
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Abstract
With the rapid development of the world’s transportation infrastructure, many long-span bridges were constructed in recent years, especially in China. However, these bridges are easily subjected to various damages due to dynamic loads (such as wind-, earthquake-, and vehicle-induced vibration) or environmental factors [...] Read more.
With the rapid development of the world’s transportation infrastructure, many long-span bridges were constructed in recent years, especially in China. However, these bridges are easily subjected to various damages due to dynamic loads (such as wind-, earthquake-, and vehicle-induced vibration) or environmental factors (such as corrosion). Therefore, structural health monitoring (SHM) is vital to guarantee the safety of bridges in their service lives. With its wide frequency response range, fast response, simple preparation process, ease of processing, low cost, and other advantages, the piezoelectric transducer is commonly employed for the SHM of bridges. This paper summarizes the application of piezoelectric materials for the SHM of bridges, including the monitoring of the concrete strength, bolt looseness, steel corrosion, and grouting density. For each problem, the application of piezoelectric materials in different research methods is described. The related data processing methods for four types of bridge detection are briefly summarized, and the principles of each method in practical application are listed. Finally, issues to be studied when using piezoelectric materials for monitoring are discussed, and future application prospects and development directions are presented. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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Open AccessReview A Review of PZT Patches Applications in Submerged Systems
Sensors 2018, 18(7), 2251; https://doi.org/10.3390/s18072251
Received: 12 June 2018 / Revised: 4 July 2018 / Accepted: 10 July 2018 / Published: 12 July 2018
Cited by 2 | PDF Full-text (3212 KB) | HTML Full-text | XML Full-text
Abstract
Submerged systems are found in many engineering, biological, and medicinal applications. For such systems, due to the particular environmental conditions and working medium, the research on the mechanical and structural properties at every scale (from macroscopic to nanoscopic), and the control of the [...] Read more.
Submerged systems are found in many engineering, biological, and medicinal applications. For such systems, due to the particular environmental conditions and working medium, the research on the mechanical and structural properties at every scale (from macroscopic to nanoscopic), and the control of the system dynamics and induced effects become very difficult tasks. For such purposes in submerged systems, piezoelectric patches (PZTp), which are light, small and economic, have been proved to be a very good solution. PZTp have been recently used as sensors/actuators for applications such as modal analysis, active sound and vibration control, energy harvesting and atomic force microscopes in submerged systems. As a consequence, in these applications, newly developed transducers based on PZTp have become the most used ones, which has improved the state of the art and methods used in these fields. This review paper carefully analyzes and summarizes these applications particularized to submerged structures and shows the most relevant results and findings, which have been obtained thanks to the use of PZTp. Full article
(This article belongs to the Special Issue Recent Advances of Piezoelectric Transducers and Applications)
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