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Smart Materials in 2018: Overview and Applications

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Smart Materials".

Deadline for manuscript submissions: closed (31 December 2019) | Viewed by 30384

Special Issue Editors

Department of Engineering, University of Campania Luigi Vanvitelli, Via Roma 29, 81031 Aversa (CE), Italy
Interests: composite materials; damage tolerance; delamination; fatigue; impact damage; crashworthiness; fuselages
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Smart structures are able to monitor their status over time and, if necessary, react properly to the stresses they are subjected to. In order to actuate the required deformations, the peculiar properties of specific types of materials are exploited, such as piezo-electric materials or shape memory alloys.

Piezo-electric materials are electroactive polymers. They are able to generate a mechanical strain resulting from an applied electrical field.

Shape memory alloys (SMAs) are a type of alloy able to contract and return to their original shape if subjected to a thermal field. Therefore, they are able to experience reversible crystallographic transformations depending on their stress and thermal state.

Proposed Topics

The followings are the topics proposed for this special issue (but not limited to):

  • Smart materials and smart structures
  • Shape memory alloys (SMAs)
  • Piezoelectric actuators
  • Modelling and simulation of smart materials
  • Properties and characterization of smart materials
  • Design for manufacture of smart materials
  • Materials selection of smart materials
  • Smart materials and structures applications

Prof. Dr. Aniello Riccio
Dr. Andrea Sellitto
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 submissions that pass pre-check are 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. Materials 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 2600 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

  • smart materials
  • piezoelectricity
  • smart structures
  • shape memory alloys

Published Papers (7 papers)

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Research

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11 pages, 4521 KiB  
Article
A Fast Beamforming Method to Localize an Acoustic Emission Source under Unknown Wave Speed
by Junfei Tai, Tian He, Qiang Pan, Dayi Zhang and Xiaoran Wang
Materials 2019, 12(5), 735; https://doi.org/10.3390/ma12050735 - 04 Mar 2019
Cited by 7 | Viewed by 2713
Abstract
The beamforming method is capable of localizing the acoustic emission source in a large-scale structure but its accuracy relies strongly on the assumed propagation speed and it is quite time consuming to apply in online monitoring. This paper proposes a fast beamforming method [...] Read more.
The beamforming method is capable of localizing the acoustic emission source in a large-scale structure but its accuracy relies strongly on the assumed propagation speed and it is quite time consuming to apply in online monitoring. This paper proposes a fast beamforming method to localize an acoustic emission source in a thin-walled structure with unknown wave speed. Firstly, the Bartlett beamforming method (BBM) is introduced into broadband Lamb wave signal processing to develop an L-shape array-based damage source localization method for a thin-walled structure. Secondly, the fast Bartlett beamforming method (FBBM) is proposed based on the characteristics of BBM. Finally, the pencil-lead break test is carried out to validate the proposed method. The test results show that the FBBM can accurately localize the damage source by any given probable wave speed much more rapidly than traditional delay-and-sum beamforming. Full article
(This article belongs to the Special Issue Smart Materials in 2018: Overview and Applications)
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9 pages, 3014 KiB  
Article
Enhancing the Energy Density of Tricritical Ferroelectrics for Energy Storage Applications
by Li He, Yan Wang, Jinghui Gao, Jianhong Wang, Tongxin Zhao, Zhixin He, Zuting Zhong, Xingmin Zhang and Lisheng Zhong
Materials 2019, 12(4), 611; https://doi.org/10.3390/ma12040611 - 18 Feb 2019
Cited by 4 | Viewed by 2630
Abstract
Recently, tricritical ferroelectrics have been drawn tremendous attention, owing to their ultrahigh dielectric permittivities of up to εr > 5 × 104, and their consideration for prototype materials in the development of high-performance energy storage devices. Nevertheless, such a materials [...] Read more.
Recently, tricritical ferroelectrics have been drawn tremendous attention, owing to their ultrahigh dielectric permittivities of up to εr > 5 × 104, and their consideration for prototype materials in the development of high-performance energy storage devices. Nevertheless, such a materials system suffers from the disadvantage of low breakdown strength, which makes its energy density far from the satisfactory level for practical application. In this paper, a material-modification approach has been reported, for improving the dielectric strength for tricritical ferroelectric materials Ba(Ti1−xSnx)O3 (BTS) through doping with Bi1.5ZnNb1.5O7 (BZN) additives. The results suggest that the electric strength has been largely improved in the modified tricritical ferroelectric material (BTSx-yBZN), and the associated energy density reaches Ue = 1.15 J/cm3. Further microstructure investigation indicates that the modified tricritical ferroelectric material exhibits homogenous fine grains with perovskite structure in crystal symmetry, and the BZN may help to form a special structure that could enhance the breakdown strength. The findings may advance the material design and development of high-energy storage materials. Full article
(This article belongs to the Special Issue Smart Materials in 2018: Overview and Applications)
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19 pages, 8933 KiB  
Article
Effect of Moisture on Shape Memory Polyurethane Polymers for Extrusion-Based Additive Manufacturing
by Irina T. Garces, Samira Aslanzadeh, Yaman Boluk and Cagri Ayranci
Materials 2019, 12(2), 244; https://doi.org/10.3390/ma12020244 - 12 Jan 2019
Cited by 35 | Viewed by 5328
Abstract
Extrusion-based additive manufacturing (EBAM) or 3D printing is used to produce customized prototyped parts. The majority of the polymers used with EBAM show moisture sensitivity. However, moisture effects become more pronounced in polymers used for critical applications, such as biomedical stents, sensors, and [...] Read more.
Extrusion-based additive manufacturing (EBAM) or 3D printing is used to produce customized prototyped parts. The majority of the polymers used with EBAM show moisture sensitivity. However, moisture effects become more pronounced in polymers used for critical applications, such as biomedical stents, sensors, and actuators. The effects of moisture on the manufacturing process and the long-term performance of Shape Memory Polyurethane (SMPU) have not been fully investigated in the literature. This study focuses primarily on block-copolymer SMPUs that have two different hard/soft (h/s) segment ratios. It investigates the effect of moisture on the various properties via studying: (i) the effect of moisture trapping within these polymers and the consequences when manufacturing; (ii) and the effect on end product performance of plasticization by moisture. Results indicate that higher h/s SMPU shows higher microphase separation, which leads to an increase of moisture trapping within the polymer. Understanding moisture trapping is critical for EBAM parts due to an increase in void content and a decrease in printing quality. The results also indicate a stronger plasticizing effect on polymers with lower h/s ratio but with a more forgiving printing behavior compared to the higher h/s ratio. Full article
(This article belongs to the Special Issue Smart Materials in 2018: Overview and Applications)
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14 pages, 8163 KiB  
Article
Analysis of the Impact Dynamics of Shape Memory Alloy Hybrid Composites for Advanced Applications
by Michele Guida, Andrea Sellitto, Francesco Marulo and Aniello Riccio
Materials 2019, 12(1), 153; https://doi.org/10.3390/ma12010153 - 05 Jan 2019
Cited by 34 | Viewed by 3984
Abstract
In this work, the behaviour of thermoplastic composites and Shape Memory Alloy Hybrid Composites (SMAHCs) for aeronautical applications is analysed and compared by means of findings from numerical analyses and experimental tests. At first, experimental tests are performed by using a drop tower [...] Read more.
In this work, the behaviour of thermoplastic composites and Shape Memory Alloy Hybrid Composites (SMAHCs) for aeronautical applications is analysed and compared by means of findings from numerical analyses and experimental tests. At first, experimental tests are performed by using a drop tower facility on both carbon fibre reinforced plastic samples and Carbon Fibre Reinforced Plastic (CFRP) samples hybridized with shape memory alloy materials. The materials properties and the different lower velocity impacts behaviours are simulated and validated by means of numerical models discretized in LS-Dyna explicit solver. For both configurations, the deformation mechanism for low intensity impacts, the absorbed energy, and the effect of rebounding upon the velocity change, and hence the amount of force, are investigated. Then, a configuration is prepared to withstand higher-energy impacts. Finally, the numerical analysis is extended for an innovative layup adapted on an aeronautical structure, which is subjected to the bird-strike phenomenon at 180 m/s and with an impacting mass of 1.8 kg according to the airworthiness requirements. In this study, SMAHCs are used to improve the composite impact response and energy absorption thanks to the superelastic effect. Full article
(This article belongs to the Special Issue Smart Materials in 2018: Overview and Applications)
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13 pages, 3471 KiB  
Article
Non Monotonous Effects of Noncovalently Functionalized Graphene Addition on the Structure and Sound Absorption Properties of Polyvinylpyrrolidone (1300 kDa) Electrospun Mats
by Giuseppe Rosario Del Sorbo, Greta Truda, Aurelio Bifulco, Jessica Passaro, Giuseppe Petrone, Bonaventura Vitolo, Giovanni Ausanio, Alessandro Vergara, Francesco Marulo and Francesco Branda
Materials 2019, 12(1), 108; https://doi.org/10.3390/ma12010108 - 30 Dec 2018
Cited by 20 | Viewed by 4279
Abstract
Graphene is an attractive component for high-performance stimuli-responsive or ‘smart’ materials, shape memory materials, photomechanical actuators, piezoelectric materials and flexible strain sensors. Nanocomposite fibres were produced by electrospinning high molecular weight Polyvinylpyrrolidone (PVP-1300 kDa) in the presence of noncovalently functionalised graphene obtained through [...] Read more.
Graphene is an attractive component for high-performance stimuli-responsive or ‘smart’ materials, shape memory materials, photomechanical actuators, piezoelectric materials and flexible strain sensors. Nanocomposite fibres were produced by electrospinning high molecular weight Polyvinylpyrrolidone (PVP-1300 kDa) in the presence of noncovalently functionalised graphene obtained through tip sonication of graphite alcoholic suspensions in the presence of PVP (10 kDa). Bending instability of electrospun jet appears to progressively increase at low graphene concentrations with the result of greater fibre stretching that leads to lower fibre diameter and possibly conformational changes of PVP. Further increase of graphene content seams having the opposite effect leading to greater fibre diameter and Raman spectra similar to the pure PVP electrospun mats. All this has been interpreted on the basis of currently accepted model for bending instability of electrospun jets. The graphene addition does not lower the very high sound absorption coefficient, α, close to unity, of the electrospun PVP mats in the frequency range 200–800 Hz. The graphene addition affects, in a non-monotonous manner, the bell shaped curves of α versus frequency curves becoming sharper and moving to higher frequency at the lower graphene addition. The opposite is observed when the graphene content is further increased. Full article
(This article belongs to the Special Issue Smart Materials in 2018: Overview and Applications)
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10 pages, 1432 KiB  
Article
On the Shaping of a Short Signal at the Output of the Receiving Piezoelectric Transducer in the Radiation-Reception System
by Boris Ee, Roman Konovalov, Sergey Konovalov, Andrey Kuz’menko and Valery Tsaplev
Materials 2018, 11(6), 974; https://doi.org/10.3390/ma11060974 - 08 Jun 2018
Cited by 2 | Viewed by 3342
Abstract
This paper theoretically and experimentally considers the pulsed mode of operation of the radiation-receiving system. The system contains two identical piezoceramic plates separated by a layer of immersion liquid (glycerin). The emitter was excited by the complex electrical signal of the special shape, [...] Read more.
This paper theoretically and experimentally considers the pulsed mode of operation of the radiation-receiving system. The system contains two identical piezoceramic plates separated by a layer of immersion liquid (glycerin). The emitter was excited by the complex electrical signal of the special shape, which consisted of two half-cycles of the sine wave (exciting and compensating) on the natural frequency of the piezoplates. The forms of these signals were calculated by the authors and described in their previous papers using the d’Alembert method. The length of the electrical signal was estimated at the output of the piezoelectric receiver. The problem was solved theoretically using the finite element method. The acoustical system was simulated with the help of the COMSOL Multiphysics modeling environment. A comparative study of the theoretical and experimental results is carried out. The form of the signal at the output of the system was calculated by the d’Alembert method, and the simulated form by the finite element method was in good coincidence with the results of experimental and full-scale modeling. It is shown that the usage of complex waveforms allows achieving a significant pulse duration reduction of the electrical voltage at the output of the receiver. Full article
(This article belongs to the Special Issue Smart Materials in 2018: Overview and Applications)
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Review

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19 pages, 6962 KiB  
Review
Overview and Future Advanced Engineering Applications for Morphing Surfaces by Shape Memory Alloy Materials
by Andrea Sellitto and Aniello Riccio
Materials 2019, 12(5), 708; https://doi.org/10.3390/ma12050708 - 28 Feb 2019
Cited by 55 | Viewed by 7021
Abstract
The development of structures able to autonomously change their characteristics in response to an external simulation is considered a promising research field. Indeed, these structures, called smart structures, can be adopted to improve the aerodynamic performance of air and land vehicles. In this [...] Read more.
The development of structures able to autonomously change their characteristics in response to an external simulation is considered a promising research field. Indeed, these structures, called smart structures, can be adopted to improve the aerodynamic performance of air and land vehicles. In this work, an overview and future applications of Shape Memory Alloys (SMA)-based smart structures are presented. The use of SMA materials seems to be very promising in several engineering sectors. Advanced SMA-based devices, designed to improve the aerodynamic performance of vehicles by modifying the shape of the spoiler and the rear upper panel, are briefly introduced and discussed in this paper. Indeed, a simplified model simulating the SMA mechanical behavior has been considered to demonstrate the feasibility of the introduced smart structures for adaptive aerodynamic applications. Numerical simulations of the investigated structures are provided as a justification of the proposed designs. Full article
(This article belongs to the Special Issue Smart Materials in 2018: Overview and Applications)
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