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Special Issue "Selected Papers from IWSHM 2017"

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

Deadline for manuscript submissions: closed (27 April 2018)

Special Issue Editors

Guest Editor
Prof. Dr. Fu-Kuo Chang

Structures and Composites Laboratory, Department of Aeronautics and Astronautics, Stanford University, Stanford, CA 94305, USA
Website | E-Mail
Phone: 650 7968899
Interests: structural health monitoring; design of integrated structures; smart structures; design and damage tolerance of composites structures; multi-functional materials
Guest Editor
Prof. Dr. Alfredo Güemes

Department Aeronautics, Polytechnic University of Madrid, 28040 Madrid, Spain
Website | E-Mail
Interests: composite materials, structural tests, structural health monitoring, embedded sensors, fiber optic sensors, monitoring of structures

Special Issue Information

Dear Colleagues,

This special issue is dedicated to the conference The 11th International Workshop on Structural Health Monitoring (IWSHM 2017) (https://web.stanford.edu/group/sacl/workshop/IWSHM2017/).

Authors of outstanding papers related to: Novel “smart” sensors, sensors for extreme environments, MEMS/NEMS sensors, fiber optics, piezoelectric, magneto-electric sensors, CNT sensors, etc. will be invited to submit extended versions of their work to the special issue for publication.

Prof. Fu-Kuo Chang
Prof. Alfredo Güemes
Guest Editor

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 monthly 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.

Published Papers (5 papers)

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Research

Open AccessFeature PaperArticle Strain Transfer for Optimal Performance of Sensing Sheet
Sensors 2018, 18(6), 1907; https://doi.org/10.3390/s18061907
Received: 28 April 2018 / Revised: 1 June 2018 / Accepted: 5 June 2018 / Published: 12 June 2018
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Abstract
Sensing sheets based on Large Area Electronics (LAE) and Integrated Circuits (ICs) are novel sensors designed to enable reliable early-stage detection of local unusual structural behaviors. Such a device consists of a dense array of strain sensors, patterned onto a flexible polyimide substrate
[...] Read more.
Sensing sheets based on Large Area Electronics (LAE) and Integrated Circuits (ICs) are novel sensors designed to enable reliable early-stage detection of local unusual structural behaviors. Such a device consists of a dense array of strain sensors, patterned onto a flexible polyimide substrate along with associated electronics. Previous tests performed on steel specimens equipped with sensing sheet prototypes and subjected to fatigue cracking pointed to a potential issue: individual sensors that were on or near a crack would immediately be damaged by the crack, thereby rendering them useless in assessing the size of the crack opening or to monitor future crack growth. In these tests, a stiff adhesive was used to bond the sensing sheet prototype to the steel specimen. Such an adhesive provided excellent strain transfer, but it also caused premature failure of individual sensors within the sheet. Therefore, the aim of this paper is to identify an alternative adhesive that survives minor damage, yet provides strain transfer that is sufficient for reliable early-stage crack detection. A sensor sheet prototype is then calibrated for use with the selected adhesive. Full article
(This article belongs to the Special Issue Selected Papers from IWSHM 2017)
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Open AccessArticle Temperature Resistant Fiber Bragg Gratings for On-Line and Structural Health Monitoring of the Next-Generation of Nuclear Reactors
Sensors 2018, 18(6), 1791; https://doi.org/10.3390/s18061791
Received: 6 April 2018 / Revised: 24 May 2018 / Accepted: 30 May 2018 / Published: 2 June 2018
Cited by 2 | PDF Full-text (20154 KB) | HTML Full-text | XML Full-text
Abstract
The harsh environment associated with the next generation of nuclear reactors is a great challenge facing all new sensing technologies to be deployed for on-line monitoring purposes and for the implantation of SHM methods. Sensors able to resist sustained periods at very high
[...] Read more.
The harsh environment associated with the next generation of nuclear reactors is a great challenge facing all new sensing technologies to be deployed for on-line monitoring purposes and for the implantation of SHM methods. Sensors able to resist sustained periods at very high temperatures continuously as is the case within sodium-cooled fast reactors require specific developments and evaluations. Among the diversity of optical fiber sensing technologies, temperature resistant fiber Bragg gratings are increasingly being considered for the instrumentation of future nuclear power plants, especially for components exposed to high temperature and high radiation levels. Research programs are supporting the developments of optical fiber sensors under mixed high temperature and radiative environments leading to significant increase in term of maturity. This paper details the development of temperature-resistant wavelength-multiplexed fiber Bragg gratings for temperature and strain measurements and their characterization for on-line monitoring into the liquid sodium used as a coolant for the next generation of fast reactors. Full article
(This article belongs to the Special Issue Selected Papers from IWSHM 2017)
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Open AccessArticle Dispersed Sensing Networks in Nano-Engineered Polymer Composites: From Static Strain Measurement to Ultrasonic Wave Acquisition
Sensors 2018, 18(5), 1398; https://doi.org/10.3390/s18051398
Received: 19 March 2018 / Revised: 17 April 2018 / Accepted: 26 April 2018 / Published: 2 May 2018
Cited by 1 | PDF Full-text (4289 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Self-sensing capability of composite materials has been the core of intensive research over the years and particularly boosted up by the recent quantum leap in nanotechnology. The capacity of most existing self-sensing approaches is restricted to static strains or low-frequency structural vibration. In
[...] Read more.
Self-sensing capability of composite materials has been the core of intensive research over the years and particularly boosted up by the recent quantum leap in nanotechnology. The capacity of most existing self-sensing approaches is restricted to static strains or low-frequency structural vibration. In this study, a new breed of functionalized epoxy-based composites is developed and fabricated, with a graphene nanoparticle-enriched, dispersed sensing network, whereby to self-perceive broadband elastic disturbance from static strains, through low-frequency vibration to guided waves in an ultrasonic regime. Owing to the dispersed and networked sensing capability, signals can be captured at any desired part of the composites. Experimental validation has demonstrated that the functionalized composites can self-sense strains, outperforming conventional metal foil strain sensors with a significantly enhanced gauge factor and a much broader response bandwidth. Precise and fast self-response of the composites to broadband ultrasonic signals (up to 440 kHz) has revealed that the composite structure itself can serve as ultrasound sensors, comparable to piezoceramic sensors in performance, whereas avoiding the use of bulky cables and wires as used in a piezoceramic sensor network. This study has spotlighted promising potentials of the developed approach to functionalize conventional composites with a self-sensing capability of high-sensitivity yet minimized intrusion to original structures. Full article
(This article belongs to the Special Issue Selected Papers from IWSHM 2017)
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Open AccessArticle Flight State Identification of a Self-Sensing Wing via an Improved Feature Selection Method and Machine Learning Approaches
Sensors 2018, 18(5), 1379; https://doi.org/10.3390/s18051379
Received: 31 March 2018 / Revised: 24 April 2018 / Accepted: 24 April 2018 / Published: 29 April 2018
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Abstract
In this work, a data-driven approach for identifying the flight state of a self-sensing wing structure with an embedded multi-functional sensing network is proposed. The flight state is characterized by the structural vibration signals recorded from a series of wind tunnel experiments under
[...] Read more.
In this work, a data-driven approach for identifying the flight state of a self-sensing wing structure with an embedded multi-functional sensing network is proposed. The flight state is characterized by the structural vibration signals recorded from a series of wind tunnel experiments under varying angles of attack and airspeeds. A large feature pool is created by extracting potential features from the signals covering the time domain, the frequency domain as well as the information domain. Special emphasis is given to feature selection in which a novel filter method is developed based on the combination of a modified distance evaluation algorithm and a variance inflation factor. Machine learning algorithms are then employed to establish the mapping relationship from the feature space to the practical state space. Results from two case studies demonstrate the high identification accuracy and the effectiveness of the model complexity reduction via the proposed method, thus providing new perspectives of self-awareness towards the next generation of intelligent air vehicles. Full article
(This article belongs to the Special Issue Selected Papers from IWSHM 2017)
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Open AccessArticle Structural Health Monitoring in Composite Structures by Fiber-Optic Sensors
Sensors 2018, 18(4), 1094; https://doi.org/10.3390/s18041094
Received: 9 February 2018 / Revised: 30 March 2018 / Accepted: 3 April 2018 / Published: 4 April 2018
PDF Full-text (22603 KB) | HTML Full-text | XML Full-text
Abstract
Fiber-optic sensors cannot measure damage; to get information about damage from strain measurements, additional strategies are needed, and several alternatives are available in the existing literature. This paper discusses two independent procedures. The first is based on detecting new strains appearing around a
[...] Read more.
Fiber-optic sensors cannot measure damage; to get information about damage from strain measurements, additional strategies are needed, and several alternatives are available in the existing literature. This paper discusses two independent procedures. The first is based on detecting new strains appearing around a damage spot. The structure does not need to be under loads, the technique is very robust, and damage detectability is high, but it requires sensors to be located very close to the damage, so it is a local technique. The second approach offers wider coverage of the structure; it is based on identifying the changes caused by damage on the strain field in the whole structure for similar external loads. Damage location does not need to be known a priori, and detectability is dependent upon the sensor’s network density, the damage size, and the external loads. Examples of application to real structures are given. Full article
(This article belongs to the Special Issue Selected Papers from IWSHM 2017)
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