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ENGINEERING (1199 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Full-text available via subscription   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 217)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 10)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 4)
Advanced Science     Open Access   (Followers: 4)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 5)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 4)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 9)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 19)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 35)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 28)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 27)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 8)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3)
Applied Nanoscience     Open Access   (Followers: 7)
Applied Network Science     Open Access  
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 2)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 7)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 7)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
Batteries     Open Access   (Followers: 3)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 9)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 3)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 13)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 40)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 4)
Coatings     Open Access   (Followers: 2)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 23)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 251)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 176)
Composites Part B : Engineering     Hybrid Journal   (Followers: 222)
Composites Science and Technology     Hybrid Journal   (Followers: 164)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 25)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 25)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 8)
Control Engineering Practice     Hybrid Journal   (Followers: 41)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 24)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  

        1 2 3 4 5 6 | Last

Journal Cover Composites Part B : Engineering
  [SJR: 2.125]   [H-I: 75]   [222 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1359-8368
   Published by Elsevier Homepage  [3031 journals]
  • Indentation test to study the moisture absorption effect on CFRP composite
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): S. Genna, F. Trovalusci, V. Tagliaferri
      The effect of moisture absorption on mechanical properties of an autoclave cured CFRP (Carbon Fibre Rinforced Polymer) is investigated in this work. FIMEC (Flat-top Cylinder Indenter for Mechanical Characterization) indentation test was adopted to study reduction of the stiffness of CFRP plates for different ageing in water. In addition, short-beam shear test was performed with the aim to validate the reduction of the shear strength. The results show that indentation test is able to assess the stiffness reduction due to the aging in water; in addition, a good correlation between the results of indentation tests and short-beam shear tests was found.

      PubDate: 2017-05-23T03:02:04Z
  • Study of graphene oxide-based 3D printable composites: Effect of the in
           situ reduction
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): Annalisa Chiappone, Ignazio Roppolo, Eric Naretto, Erika Fantino, Flaviana Calignano, Marco Sangermano, Fabrizio Pirri
      This study demonstrates that, PEO-acrylates composite containing graphene oxide (GO) can be easily 3D printed from water based formulations. Exploiting the good water affinity of graphene oxide, the filler can be easily dispersed in oligomers formulations and printed by using a low cost DLP equipment. Then the UV post curing process, which is always mandatory after a DLP process, is exploited to in situ reduce the graphene oxide embedded in the matrix; similarly a thermal treatment is also investigated as post process. Different 3D structures are submitted to the reduction post-treatments and the influence of the UV and thermal reduction on the mechanical and electrical properties of the printed objects is investigated. The present work shows the possibility to easily produce 3D shaped GO-based composites whose final properties can be tailored trough a UV or thermal post process performed on the printed parts that induces the in situ reduction of GO embedded in the polymer matrix.
      Graphical abstract image

      PubDate: 2017-05-23T03:02:04Z
  • Creep behaviour of polylactic acid reinforced by woven hemp fabric
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): Massimo Durante, Antonio Formisano, Luca Boccarusso, Antonio Langella, Luigi Carrino
      Woven hemp fabric reinforced polylactic acid composites with different fibre volume fraction (20, 30 and 40%) were manufactured by compression moulding process. To better understand the industrial application limits of the investigated bio-composite, flexural and impact properties were determined and compared to those of the unreinforced bio-polymer and the creep behaviour at different values of temperature was widely investigated adopting the Arrhenius theory. In addition, to predict the long-term mechanical performance of the investigated bio-composite, the possibility to use the Time-Temperature Superposition model was investigated. For this purpose, Dynamic-Mechanical tests were conducted to evaluate the activation energy and then to apply the Time-Temperature Superposition model to the compliance curves, obtained by short-time creep tests under different load conditions. Therefore, to examine the validity of the theoretical model, experimental long-time tests were also carried out. The results show interesting mechanical properties and a good fit between the theoretical and the experimental creep curves, particularly when the fibre volume fraction was equal to 20 and 30%.

      PubDate: 2017-05-23T03:02:04Z
  • Enhanced fatigue behavior under internal pressure of CNT reinforced
           filament wound cracked pipes
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): Mustafa Taşyürek, Necmettin Tarakçioğlu
      In this study, the fatigue behavior of filament winding pipes was determined experimentally under internal pressure. Samples were produced by ultrasonication and the filament wound methods. In order to produce the CNTs/E Glass/Epoxy nanocomposite, CNTs and E-glass reinforcements and Bisphenol-A epoxy polymer matrix were used. Test specimens had antisymmetric six layers. All specimens had ±55° winding angle. During all the experiments, the surface crack, fatigue crack growth rate and reinforcement condition of carbon nanotube were investigated. Two different rates of CNT (0.5% and 1%) were compared with the pure epoxy material. Effect of CNT on fatigue life was investigated experimentally. Cracks on the pipes for the fatigue tests had the aspect ratio of a/c = 0.2 and crack depth range between a/t = 0,25 and 0,50. Each test was repeated at least 3 times. Three different maximum stress levels were determined for the tests, which were 40%, 50% and 60% of the ultimate hoop stress. Fatigue life of nanocomposite pipes was found to increase with enhanced inter-laminar adhesion via CNTs. Stopping crack progression, bridging mechanism and mechanical interlocking between fibers of CNTs had been justified by SEM images. As a conclusion, material properties of GRP pipes were discussed by determining the effect of the reinforcement of carbon nanotubes.

      PubDate: 2017-05-23T03:02:04Z
  • Mean field homogenization methods for strand composites
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): Atul Jain, Bo Cheng Jin, Steven Nutt
      A common method for dealing with in-process manufacturing waste is to cut the prepreg scrap into rectangular strands, and use these strands to produce composites. The properties of the strand composite depend on a number of factors, including the aspect ratio and orientation of the strand. Predictive simulations are required to determine the stiffness of such materials so that optimal composites can be fabricated without extensive experimental testing. In this work, we present a hybrid method for predicting the stiffness of strand composites by using a combination of finite element and analytic mean field homogenization techniques. The proposed model combines the versatility of finite element models and the ease of computation of analytic schemes. This method can be used to model strands of any shape and orientation distribution; it also presents possibilities for detailed parametric analysis. The proposed method yields predictions that are consistent with experimental measurements and provides insights about testing protocols and observed scatter in experimental results.

      PubDate: 2017-05-23T03:02:04Z
  • Concrete cover effect on the bond of GFRP bar and concrete under static
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): Ana Veljkovic, Valter Carvelli, Marcin Michal Haffke, Matthias Pahn
      Paper presents assessment of bond behaviour between GFRP bars and concrete, investigated through set of centric and eccentric pull-out specimens. Main parameters under investigation are 1) bar external surface, 2) concrete mechanical properties and 3) concrete cover. Corresponding tests with steel reinforcement are performed for comparison in some cases. DIC technique was used for recording and evaluating of strain field on frontal side of eccentric specimens. Consequently, cracking patterns and local bond behaviour are described in details. Increasing of concrete mechanical properties always enhanced bond strength and delayed cracking of concrete cover. Ribbed GFRP bars showed excellent bonding performance when combined with low concrete cover. Their low splitting tendency and specific rib geometry developed better bond behaviour in case of eccentric tests, which showed the possibility of a proper prediction of the bonding behaviour of structural components.

      PubDate: 2017-05-23T03:02:04Z
  • Titanate nanotubes and nanosheets as a mechanical reinforcement of
           water-soluble polyamic acid: Experimental and theoretical studies
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): Christian Harito, Dmitry V. Bavykin, Mark E. Light, Frank C. Walsh
      Titanate nanosheets (TiNS), titanate nanotubes (TiNT), and scrolled titanate nanosheets (STiNS) were used to synthesise polymer nanocomposites by solution processing. The hardness was found to increase by 90% on addition of 2% TiNS while the modulus (Er) increased by 103% compared to the pure polymer. Small angle X-ray scattering (SAXS) measurements of composite films were used to study alignment of nanostructures within the polymer. The obtained data on mechanical properties of composites have been tested against theoretical values and it was established that both nanostructures alignment as well as their mechanical properties affect the hardness and modulus of the polymer composites. At a low content of TiNS, the reinforcement behaviour matched well with Halpin-Tsai theory which assumes the filler has unidirectional orientation. After addition of 2 wt% TiNT, the hardness and modulus of the polyamic acid salt composites increased by 91% and 165%, respectively, and were higher than theoretical predictions, indicating that both TiNT and STiNS, prepared by hydrothermal synthesis, may have higher mechanical properties than bulk TiO2. At a high filler loading (>2 wt%), the mechanical properties of composites do not fit established theories due to agglomeration of titanate nanostructures.

      PubDate: 2017-05-23T03:02:04Z
  • On the use of selective stitching in stiffened composite panels to prevent
           skin-stringer debonding
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): A. Riccio, P. Linde, A. Raimondo, A. Buompane, A. Sellitto
      Composite laminates are generally characterized by poor mechanical properties along the thickness direction, therefore they are highly susceptible to delaminations. A potential increase in structural efficiency may be obtained by using 3D reinforcements technologies. In this paper, an experimental/numerical study is presented focusing on the effects of a single reinforcement seam of stitches along the edge of a stringer foot, in a stiffened composite panel. Three-point bending tests have been performed on a skin-stringer configuration by considering variations of the skin thickness, the stitching technique, the pitch and the yarn diameter. Then, a Finite Element Model has been developed capable to simulate the mechanical behaviour of stiffened composite panels with selective stitching and to assist the design of more complex geometrical configurations by estimating the damage behaviour, as well as the onset and the propagation of delamination taking into account the effect of the selective stitching. The numerical results, in terms of load vs applied displacements, have been found in good agreement with the experimental data proving the effectiveness of the introduced numerical model. The numerical results have confirmed the potential beneficial effects of stitching in terms of delay of the crack initiation and growth, of smoother delamination profile, of increase in the stiffness of the structure with a reduction of the delamination area.

      PubDate: 2017-05-23T03:02:04Z
  • Carbon nanotubes stabilize high temperature phase and toughen Al2O3-based
           thermal barrier coatings
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): S. Ariharan, Ambreen Nisar, N. Balaji, S.T. Aruna, Kantesh Balani
      In this work, alumina (Al2O3) reinforced with zirconia viz., 0, 3, and 8 mol% yttria doped (i.e., ZrO2, 3YSZ, and 8YSZ), and 4 wt% carbon nanotube (CNT) are coated on Inconel 718 substrate by atmospheric plasma spraying (APS). Reinforcement by CNT and 3YSZ has led to a substantial enhancement in the fracture toughness from 3.89 MPa m1/2 (for Al2O3) to 5.90 MPa m1/2 in the reinforced composite. It is observed that CNT has contributed ∼5–12% toughness enhancement, whereas ∼15% contribution to toughening is obtained via tetragonal to monoclinic (t→m) transformation of zirconia. Moreover, CNTs not only assist the t→m transformation but also enhance the toughness value of Al2O3-based thermal barrier coatings (TBC) near to its upper theoretical bound estimated using modified fractal model. Moreover, the effective thermal conductivity is estimated using modified theoretical models embracing the aligning factor of CNT in APS coatings, which unequivocally confirms the superiority of Al2O3 reinforced with 3YSZ and CNT as a potential TBC.
      Graphical abstract image

      PubDate: 2017-05-23T03:02:04Z
  • Experimental characterization and micrography of 3D printed PLA and PLA
           reinforced with short carbon fibers
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): Rafael Thiago Luiz Ferreira, Igor Cardoso Amatte, Thiago Assis Dutra, Daniel Bürger
      The objective of this work is the mechanical characterization of materials produced by 3D printing based on fused filament fabrication (FFF, analogous to FDM®). The materials chosen are a polylactic acid (PLA) and a PLA reinforced with short carbon fibers in a weight fraction of 15 % (PLA+CF). In view of the FFF nature, which produces specimens layer by layer and following predefined orientations, the main assumption considered is that the materials behave like laminates formed by orthotropic layers. If the 3D printing is made in the 1 − 2 plane, where 1 is the deposition direction and 2 is a direction perpendicular to 1, the mechanical properties obtained are the tensile moduli E 1 and E 2 , the Poisson ratios ν 12 and ν 21 , the shear modulus G 12 and related strength properties. For this purpose, only unidirectional or specially oriented specimens are used. After tests up to material failure, scanning electron microscopy (SEM) is employed to observe fracture surfaces. It was noticed that, in the microstructure of the PLA+CF, the short carbon fibers stay highly oriented with the material deposition direction in the FFF specimens. This fact, and the also observed length of the fibers, explains differences in material properties encountered among the performed experiments.

      PubDate: 2017-05-23T03:02:04Z
  • Studies on toughened polycarbonate/multiwalled carbon nanotubes
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): Nisha Bagotia, Veena Choudhary, D.K. Sharma
      The electrically conducting nanocomposites (NCs) of toughened polycarbonate (PC) fabricated by using melt blending method with different loadings of multiwalled carbon nanotube (MWCNTs) ranging from 0.25 to 10 phr were studied in this paper. Thus prepared NCs were characterized for morphology (scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and X-ray diffraction), mechanical properties, thermal property, electrical conductivity (using two probe method) and electromagnetic interference shielding effectiveness (using vector network analyzer). The impact strength of toughened PC prepared by blending PC with 5 wt% of ethylene methyl acrylate (EMA) copolymer having impact strength 318 J/m i.e. 381% improvement as compared to neat PC was further increased to 19% (378 J/m) after 1 phr addition of MWCNTs. Maximum tensile strength and modulus of PC/EMA-MWCNT NCs (about 39 and 60% increase respectively as compare to PC/EMA blend) was achieved at the loading of 10 phr MWCNT. An electrical percolation threshold (p c ) occurred at 1 phr of MWCNTs and higher electrical conductivity value about 1.56 × 10−3 S cm−1 was attained for PC/EMA (95/5) having 10 phr of MWCNTs. Maximum EMI shielding effectiveness of toughened PC having 10 phr of MWCNTs was observed as ∼ −26 dB in X-band with samples of 3 mm thickness.
      Graphical abstract image

      PubDate: 2017-05-23T03:02:04Z
  • Enhancing the interfacial bond strength of cement nanocomposite with
           carbonate nanostructure
    • Abstract: Publication date: 1 September 2017
      Source:Composites Part B: Engineering, Volume 124
      Author(s): W. Sekkal, A. Zaoui
      The future development of cementitious materials with nanoparticles or nanoscale fibers requires the ability to understand and to improve the interfacial bonding in order to develop a stronger, tougher and more robust concrete nanocomposite. The purpose of this work is to study the adhesion contact as well as the interfacial strength between calcium silicates hydrates gel (C-S-H) and calcite surfaces. The application of lateral and longitudinal strain on both surfaces shows that the elastic energy of C-S-H to ensure accommodation at the interface is lower than the one obtained for calcite. Our results show that 1 Å is the ideal distance to have a good adhesion between (001) C-S-H and (104) calcite surfaces. We also demonstrate that the presence of water molecules at the interface absorb the excess energy and thus contribute to the stabilization of the interface. Besides, the results indicate that the interfacial bonding between C-S-H and calcite improves the ductility of the cement nanocomposite when the gel porosity is about 30%. Under uniaxial and shear stresses, the nanostructure shows a heterogeneous mechanical behavior. Particularly, the interfacial shear strength enhances while applying a shear stress, which is due to the structure and the dynamic differences of the layered structure since the calcium silicate layer, constructed by Ca–O and Si–O ionic-covalent bonds, has stronger cohesive force than the interlayer H-bond network.

      PubDate: 2017-05-23T03:02:04Z
  • Reinforcing effects of glass fiber/p-DCPD with fiber concentrations,
           types, lengths and surface treatment
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Dong-Jun Kwon, Pyeong-Su Shin, Jong-Hyun Kim, Ha-Seung Park, Yeong-Min Beak, K. Lawrence DeVries, Joung-Man Park
      The effects of various reinforcement parameters in glass fiber (GF)/poly dicyclopentadiene (p-DCPD) composites were studied help facilitate the manufacture of high performance composites, especially for use at low temperatures. These parameters included different types, lengths, concentrations, and surface treatments of GF. Optimum length, concentration, interfacial conditions, and type of GF are important in the fabrication of composites with the enhanced mechanical and impact properties. The interfacial conditions of GF in the p-DCPD matrix where altered using norbornene functional silane as determined by mechanical measurements for the different fiber types and conditions. The optimal concentration of H-GF, of 100 mm length, in GF/p-DCPD composites for the production of high mechanical property was found to be 20 wt%. This was attributed to the good mobility of 100  mm GF in the matrix such that at 20 wt% in GF/p-DCPD there was low entanglement between the GFs. Norbornene treatment of the GF resulted in improved reaction between the GF and the p-DCPD. This is thought to be due to the norbonene group's similarity to the p-DCPD matrix improving the reaction between the GF and the p-DCPD matrix.

      PubDate: 2017-05-18T10:18:19Z
  • Improving the mechanical, thermal, dielectric and flame retardancy
           properties of cyanate ester with the encapsulated epoxy resin-penetrated
           aligned carbon nanotube bundle
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Qingbao Guan, Li Yuan, Yi Zhang, Aijuan Gu, Guozheng Liang
      Epoxy resins-penetrated aligned carbon nanotube bundles (ACNTB) microcapsules (ACNTB@EP MCs) and pristine ACNTB with porous structure were introduced into thermosetting cyanate ester (CE) resins to prepare high performance CE composites. Owing to the epoxy resins-penetrated ACNTB with significantly decreased defects and the chemical interaction at the interface of MCs and CE resin, CE with appropriated MCs shows better comprehensive performance than CE/ACNTB composite when the two composites contain the same amount of ACNTB. CE with 5 wt% MCs (CE/5MCs) shows the optimal flexural strength, impact resistance and tensile strength, which are 59%, 45% and 32% higher than that of CE, respectively. CE with 15 wt% MCs (CE/15MCs) shows 24% higher in thermal conductivity, 35.1% lower in PHRR value than CE. CE/15MCs also exhibits the highest dielectric constant of 12.8–16.6 and a low dielectric loss of 0.022–0.066. The attractive performances of CE/MCs composites prove that the ACNTB@EP MCs are multi-functional fillers, which can simultaneously act as toughening agent, reinforcement while improving the thermal stability, flame retardancy and dielectric properties for high temperature thermosetting resins.

      PubDate: 2017-05-18T10:18:19Z
  • Quantitative comparison of optical transmission scanning with conventional
           techniques for NDE of impact damage in GFRP composites
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Anton Khomenko, Oleksii Karpenko, Ermias G. Koricho, Mahmoodul Haq, Gary L. Cloud, Lalita Udpa
      Robust and quantitative non-destructive evaluation (NDE) is essential for damage characterization in advanced materials, such as glass fiber reinforced polymer (GFRP) composites. Previous work demonstrated the capabilities of an optical transmission scanning (OTS) system, including an advanced image processing algorithm, for rapid and non-contact NDE of healthy and impacted GFRP samples. The number of delaminations and their contours in the test samples were accurately identified. In this paper, damage was introduced in GFRP samples by low velocity impacts of different energies, and OTS was validated by comparing the inspection results with conventional NDE techniques, including pulse-echo ultrasonic testing (UT) and UV dye penetrant testing (UV DPT). In addition, quantitative comparisons of damage severity were made for OT scans and UT C-scans by converting images to a normalized damage metric. Experimental results demonstrated that the estimated extent of impact damage agreed very well for all used techniques. Thus, OTS combines the cost-effectiveness and rapidity of qualitative techniques (e.g., UV DPT) with the more robust and comprehensive data analysis provided by quantitative methods (e.g., UT).

      PubDate: 2017-05-18T10:18:19Z
  • Free vibrations of Bernoulli-Euler nano-beams by the stress-driven
           nonlocal integral model
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Andrea Apuzzo, Raffaele Barretta, Raimondo Luciano, Francesco Marotti de Sciarra, Rosa Penna
      Nonlocal theories of Continuum Mechanics are widely used in order to assess size effects in nano-structures. In this paper, free vibrations of nano-beams are investigated by making recourse to the novel stress-driven nonlocal integral model (SDM). Equations of motion governing the dynamics of a Bernoulli-Euler nano-beam are consistently formulated and numerically integrated by Matlab. Selected case studies involving structures of nanotechnological interest are examined. Natural frequencies, evaluated according to the SDM, are compared with those obtained by the Eringen differential law (EDM) and by the gradient elasticity theory (GradEla). SDM provides an effective methodology to describe nonlocal phenomena in NEMS.

      PubDate: 2017-05-18T10:18:19Z
  • Poly (propylene carbonate)-based in situ nanofibrillar biocomposites with
           enhanced miscibility, dynamic mechanical properties, rheological behavior
           and extrusion foaming ability
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Tairong Kuang, Kaican Li, Binyi Chen, Xiangfang Peng
      Poly (propylene carbonate) (PPC) foams have attracted more attention in recent years because of their biodegradability and the fixation of carbon dioxide (CO2). Despite their many attractive features, a relatively low decomposition temperature, a low glass transition temperature (Tg), weak mechanical properties and poor melt strength of PPC matrix limited their commercial applications as a viable candidate for conventional plastics. In this study, we report a facile, effective, low-cost and eco-friendly approach for the preparation of PPC/PBS/PTFE ternary in situ nano-fibrillar biocomposites to significantly improve the strength and foaming ability of PPC without sacrificing their excellent biodegradability. The in situ nano-fibrillar networks in the PPC/PBS matrix demonstrated that significant reinforcement effects on the matrix strength, dynamic mechanical and rheological properties at low PTFE contents. In contrast to pure PPC, Tg increased by 15 °C, 851% higher in storage modulus and 17 times enhancement in the initial viscosity of biocomposites. In continues extrusion foaming process, the PBS domains and PTFE nano-fibrils network generated remarkable synergistic effects on the foaming behavior, resulted in higher cell densities (two orders of magnitude), compressive modulus (30 times) and compressive strength (20 times) of PPC/PBS/PTFE (70/30/3) biocomposites.

      PubDate: 2017-05-18T10:18:19Z
  • Real-time detection of low-velocity impact-induced delamination onset in
           composite laminates for efficient management of structural health
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Byeong-Wook Jang, Chun-Gon Kim
      Carbon fiber reinforced polymer (CFRP) laminates have been becoming primary structures in the aerospace industry because of their high specific strength and stiffness. However, CFRP laminates have susceptibility to low-velocity impact events which can easily induce internal or hidden damages such as delamination. Such impacts frequently arise during maintenance, flight operation or in-service events. Thus, composite structures have to be irregularly inspected in addition to the periodic maintenance for ensuring the structural health. However, such irregular inspections can inherently incur the overall maintenance cost because it has to be performed in all suspicious cases of damages. For this reason, the methodology for accurately realizing the onset of delamination induced by low-velocity impact events is required for reducing the operating cost of composite structures. In this paper, the potential of using high speed fiber Bragg grating (FBG) sensing system for detecting the delamination onset was studied for thick CFRP laminates. Because FBG sensors can be simply multiplexed to capture the structural responses, the proposed method in this study can be quite attractive for an efficient impact monitoring system. To obtain the impact response signals and contact force histories, several low-velocity impact experiments were performed in a range of 1–30 J. From the signal processing of these experimental data, the meaningful damage index was introduced using the detail components of wavelet transformed sensor signals. Although this result is in the preliminary step, such damage index can be useful for applying an in-situ impact damage assessment system to the real composite structures in the near future.

      PubDate: 2017-05-18T10:18:19Z
  • Combining short flax fiber mats and unidirectional flax yarns for
           composite applications: Effect of short flax fibers on biaxial mechanical
           properties and damage behaviour
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Mohamed Habibi, Luc Laperrière, Gilbert Lebrun, Lotfi Toubal
      Short flax fibers mats, unidirectional (UD) layers of flax yarns, and an assembly of these two, are used as reinforcements for an epoxy matrix composite. The tensile and flexural properties of the three different composites, in both longitudinal and transverse directions, were studied in order to highlight the effect of mat surface density, using two stacking sequences. A slight decrease of the measured longitudinal properties is observed when low levels of short fibers content are used. This is compensated by a significant decrease of the material variability, a significant increase of the transverse properties, and a favorable effect on the fracture behaviour of the tested specimens. Damage evolution is monitored using acoustic emission (AE) and the use of multivariable analysis of the collected data has given a clear description of the different damage modes, their evolution and their contribution to overall composite failure. Different damage behaviours are observed for the mats and UD samples. Most importantly their combination into a single reinforcement has a positive effect on damage type and evolution. The presence of short fibers in the composite reduces the crack propagation along the fibers/matrix interface, which reduces splitting and transforms the fracture surface from a serrated fracture surface to a flat and confined fracture surface.

      PubDate: 2017-05-18T10:18:19Z
  • Effect of matrix voids, fibre misalignment and thickness variation on
           multi-objective robust optimization of carbon/glass fibre-reinforced
           hybrid composites under flexural loading
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Mehdi Kalantari, Chensong Dong, Ian J. Davies
      The robust and optimal design of carbon/glass fibre-reinforced epoxy hybrid composite laminates under the constraint of a specified minimum flexural strength was investigated in this study. Two conflicting objectives, minimizing material cost and weight, were considered with the design variables being fibre type, fibre orientation angle and fibre volume fraction of the laminas. Three sources of uncertainties, namely, fibre misalignment, lamina thickness variation and the presence of matrix voids were incorporated into the model. This multi-objective robust optimization problem was solved by combining a modified version of the non-dominated sorting genetic algorithm (NSGA-II) with a simple genetic algorithm (GA) as an anti-optimizer. Pareto optimal and robust solutions were found for different levels of minimum flexural strength and the significance of each uncertainty source on the optimal cost and weight of the optimal designs were investigated by conducting analysis of variance (ANOVA) tests. The results indicated that, in general, all three uncertainties affected the cost and weight of the optimal designs with the effect of voids being more critical for void contents of greater than 2%.

      PubDate: 2017-05-18T10:18:19Z
  • Nonlinear harmonic vibration analysis of fluid-conveying
           piezoelectric-layered nanotubes
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Zia Saadatnia, Ebrahim Esmailzadeh
      Nonlinear harmonic vibration of a piezoelectric-layered nanotube conveying fluid flow is investigated. The mathematical modeling of the structure is developed by means of the nonlocal theory and energy approach. The piezoelectric layer is assumed to be slender and the fluid flows through the nanotube at a uniform velocity. The forced vibration of the system is resulted from an external loading and hence, the parametric excitation is analyzed. Three different scenarios for its resonance conditions, known as the primary, parametric, and the simultaneous primary-parametric resonances, employing a strong perturbation technique known as the multiple time-scales method, are investigated. The effects of the variation of different parameters, such as the applied voltage, piezoelectric layer, nonlocal parameter and the fluid flow velocity, on both the frequency-amplitude relationship and the frequency response of the system are studied. Finally, a detailed discussion on the numerical results obtained were fully presented.

      PubDate: 2017-05-18T10:18:19Z
  • Tribological performance of in-situ epoxy composites filled with
           micro-sized ZrB2 particles
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Yicheng Wu, Zhiqiang Yu, Xiaoyan Liu
      The tribological performance of in-situ epoxy composites reinforced with micro-sized particles of zirconium diboride (ZrB2) were investigated in dry sliding conditions. The frictional heat flow in the contact areas was analyzed using finite element modeling. It was found that the dominant wear mechanisms of composites were changed from adhesive wear to abrasive wear due to the introduction of ZrB2 particles under the imposed sliding conditions. The coefficient of friction (CoF) and coefficient of wear K of composites decreased significantly with the increase of ZrB2 particle content. The increase in thermal conductivity due to the addition of ZrB2 particles was proposed to contribute to the enhanced wear resistance under given sliding conditions.

      PubDate: 2017-05-18T10:18:19Z
  • In situ preparation of reduced graphene oxide/DOPO-based phosphonamidate
           hybrids towards high-performance epoxy nanocomposites
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Wenwen Guo, Bin Yu, Yao Yuan, Lei Song, Yuan Hu
      The work reports a strategy based on piperazine-reduced graphene oxide (rGO)/piperazine-based DOPO-phosphonamidate (PiP-DOPO) to overcome the challenge of the dispersion of graphene and mechanical deterioration of epoxy resin (EP) matrix with additive-type flame retardants. Graphene oxide (GO) was functionalized and reduced by piperazine simultaneously, and then incorporated into PiP-DOPO through in situ reaction, resulting in the formation of the hybrids (PD-rGO). Subsequently, the PD-rGO was incorporated into epoxy resin (EP) to fabricate nanocomposite. The structure and thermal properties of PD-rGO were well characterized. The presence of PD-rGO in EP improved the char yields at 700 °C and reduced the maximum mass loss rate under nitrogen, indicating the improved thermal stability at elevated temperature. The evaluation of combustion behavior demonstrated that the PHRR and THR values were decreased significantly by 43.0% and 30.2% by the addition of 4 wt% PD-rGO10 (10 wt% rGO in hybrid) in EP respectively, in comparison to neat EP. The epoxy composite with 4 wt% PD-rGO5 (5 wt% rGO in hybrid) could pass UL-94 V0 rating and the LOI was 28.0%. The flame retardant mechanism could be attributed to the synergism between two compositions in PD-rGO hybrid: the PiP-DOPO was favorable to flame spread inhibition in UL-94 burning test, while the barrier effect of graphene was dominant in terms of heat release rate suppression. Moreover, the addition of PD-rGO hybrid led to slightly improved storage modulus and tensile strength, due to the high stiffness of graphene in hybrids. The PD-rGO hybrid combines the outstanding mechanical behavior of graphene with the good flame retardant effect of DOPO-based compounds, which provides a promising solution to high performance epoxy nanocomposites with improved flame retardant and mechanical properties simultaneously.

      PubDate: 2017-05-18T10:18:19Z
  • Basalt fibers as a sustainable and cost-effective alternative to glass
           fibers in sheet molding compound (SMC)
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Amir Asadi, Ferdinand Baaij, Hendrik Mainka, Michael Rademacher, Jeffrey Thompson, Kyriaki Kalaitzidou
      The focus of this study is to explore the feasibility of using basalt fibers (BF) as a potential sustainable alternative to glass fibers (GF) in sheet molding compounds (SMC) to reduce the weight and cost of conventional GF SMC. The interfacial interactions for BF/epoxy and GF/epoxy composites were assessed through single fiber fragmentation tests. The mechanical properties, including tensile and flexural modulus and strength, impact strength and thermomechanical properties for 25 wt% BF/epoxy composites made using SMC were determined and directly compared to 25 wt% GF/epoxy SMC composites. As indicated by the single fiber fragmentation tests, the two composites had similar interfacial shear strength (IFSS) and consequently similar adhesion at the fiber-epoxy interface. In addition, no distinguishable differences were found in the curing behavior of the two SMC composites. The storage modulus of the 25 wt% BF/epoxy composites was found to be higher than that of 25GF/epoxy in the glassy state. Moreover, the average tensile and flexural properties (both absolute and specific values) of the 25 wt% BF/epoxy SMC composites were higher or at least equal to those of 25 wt% GF/epoxy SMC composites. No difference in the impact strength of the two composites was recorded considering the statistical variation. In general, BF/epoxy SMC composites showed better or equal mechanical performance compared to GF/epoxy SMC composites suggesting that BF may be an alternative to GF with the potential to lead to lower cost SMC composites.

      PubDate: 2017-05-18T10:18:19Z
  • Mixed-mode I/II delamination fatigue strengthening of polymer composites
           using z-pins
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): F. Pegorin, K. Pingkarawat, A.P. Mouritz
      An experimental investigation is presented into the improvement to the delamination fatigue resistant properties of z-pinned carbon fibre–epoxy composite under mixed-mode I/II cyclic interlaminar loading. Delamination fatigue tests are performed on unpinned and z-pinned composites under different mixed-mode ratios spanning mode I to mode II interlaminar cyclic conditions. The fatigue resistance and fatigue strengthening mechanisms induced by the z-pins is dependent on the cyclic mixed-mode ratio. The threshold critical strain energy release rate needed to initiate delamination growth in the z-pinned composite increases with the GI-to-GII ratio. The fatigue crack growth rate slows considerably and the critical strain energy release rate for fast fatigue fracture increases with the GI-to-GII ratio. The delamination fatigue strengthening induced by the z-pins increases with the GI-to-GII ratio due to a transition in the crack bridging toughening process from pin pull-out under mode I dominated loads to combined tensile and shear fracture under mixed-mode loads to pin shear rupture under mode II dominated loads. It is also found that the effect of the GI-to-GII ratio on the fatigue properties is greater for the z-pinned composite compared to the unpinned laminate due to the high fatigue sensitivity of z-pins to the mixed-mode ratio.

      PubDate: 2017-05-18T10:18:19Z
  • In-situ formed graphene nanoribbon induced toughening and thermal shock
           resistance of spark plasma sintered carbon nanotube reinforced titanium
           carbide composite
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): M. Sribalaji, Biswajyoti Mukherjee, Srinivasa Rao Bakshi, P. Arunkumar, K. Suresh Babu, Anup Kumar Keshri
      CNTs (2 wt%) reinforced TiC composite with WC (3.5 wt%) as sintering aid was densified using SPS technique at 1600 °C. In-situ formation of wide GNRs (Graphene nanoribbon) was observed due to CNT unzipping in TiC-WC-CNT (TWC) pellet. A phenomenal increase in fracture toughness (∼118%) was observed in TWC pellet compared to TiC. This significant improvement was due to novel toughening mechanisms like GNR grain wrapping, GNR crack bridging and crack bifurcation. Further, TWC pellet showed ∼48% improved thermal shock resistance compared to TiC, which could be due to the suppressed large thermal cracks by CNT and in-situ formed GNR.
      Graphical abstract image

      PubDate: 2017-05-18T10:18:19Z
  • Nonlinear flexural and vibration response of geometrically imperfect
           gradient plates using hyperbolic higher-order shear and normal deformation
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Ankit Gupta, Mohammad Talha
      This paper investigates the sensitivity of nonlinear flexural and vibration response of shear deformable functionally graded material (FGM) plates to the initial geometrical imperfections. The formulations are based on recently developed non-polynomial higher-order shear and normal deformation theory by authors. The theory accounts for nonlinear variation in the in-plane and transverse displacement through the thickness. It also accommodates thickness stretching effect without employing shear correction factor. The novelty of this theory is that it contains only four unknowns, unlike several other shear deformation theories which contain five or more unknowns. The equations of motion are derived using variational principle. The initial geometric imperfections have been incorporated using generic imperfection function. Material properties of the FGM plates are assumed to be varying continuously in the thickness direction according to a simple power law and exponential law. Convergence and comparison studies have been carried out to establish the authenticity and reliability of the solution. The numerical results are highlighted with various geometric imperfections and system parameters.

      PubDate: 2017-05-18T10:18:19Z
  • Thermo-elastic effects on shear correction factors for functionally graded
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Tae-Kyung Lim, Ji-Hwan Kim
      Functionally Graded Materials (FGMs) have been used as advanced structures in high temperature regions for excellent thermal barriers. In this regard, present study considers the compensation of the shear stress effects in thermal environments to be more crucial than conventional evaluation. As the beam model with thermo-mechanical behavior, the material properties are considered temperature-dependent and vary continuously in the thickness direction. For the structure, First-order Shear Deformation Theory (FSDT) is employed in the formulation. And the model is based on the neutral surface concept to consider the un-symmetric properties of materials in the thickness direction. To check the validity of present works, results are compared with previous data. Furthermore, numerical analyses are performed with the temperature-dependent shear correction factors. Also, three types of model such as the Power-law (P-), Exponential (E-) and Sigmoid (S-) FGMs are discussed in detail.

      PubDate: 2017-05-18T10:18:19Z
  • Graphite reinforced polyvinylidene fluoride composites an efficient and
           sustainable solution for electromagnetic pollution
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Nina Joseph, Jobin Varghese, Mailadil Thomas Sebastian
      Graphite flakes reinforced polyvinylidene fluoride (PVDF) composites were prepared and investigated the influence of DC (Direct Current), AC (Alternating Current) conductivity, sample thickness as well as presence of conductive layer on its electromagnetic interference (EMI) shielding effect. The graphite incorporated PVDF composite with sample thickness of 1 mm exhibit good shielding properties of about 55–57 dB in the frequency range of 8.2–18 GHz for highest filler loading. These composites exhibit absorption as the primary mechanism for EMI shielding. Addition of graphite decreases the coefficient of thermal expansion (CTE) and improved the mechanical properties. The EMI shielding effect improved with increase in sample thickness and by incorporating a conductive layer to the graphite flake composite. The graphite flake based composites are found to be lightweight, thin and good EMI shielding materials that can be tuned to wide range of shielding applications.

      PubDate: 2017-05-18T10:18:19Z
  • Selective localization of organic montmorillonite in
           poly(l-lactide)/poly(ethylene vinyl acetate) blends and the resultant
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Chang-ming Liu, Fang-fang Ma, Zhi-xing Zhang, Jing-hui Yang, Yong Wang, Zuo-wan Zhou
      A small quantity of organic montmorillonite (OMMT) was introduced into an immiscible poly(l-lactide)/poly(ethylene vinyl acetate) (PLLA/EVA) blend. The selective location state of OMMT, the blend morphologies and the microstructure of the blend composites were systematically investigated. The theoretical calculation based on interfacial tensions and experimental observations showed that OMMT selectively located in the rigid PLLA component. Apparent morphological changes were observed for the blend composites. Rheological measurements showed that OMMT at relatively high content formed the percolated network structure in the blend composites. Tensile measurements showed that OMMT exhibited excellent reinforcement effect for the immiscible PLLA/EVA blends. Furthermore, tensile creep behavior measurements showed that incorporating OMMT into the immiscible PLLA/EVA blends facilitated the apparent enhancement of creep stability. The microstructure-performance relationship of the blend composites was then analyzed.

      PubDate: 2017-05-13T03:59:15Z
  • Aramid hybrid composite laminates reinforced with inorganic fullerene-like
           tungsten disulfide nanoparticles
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Danica M. Simić, Dušica B. Stojanović, Saša J. Brzić, Ljubica Totovski, Petar S. Uskoković, Radoslav R. Aleksić
      Combination of phenolic resin with poly (vinyl butyral), PVB, is often used as impregnation of aramid fabrics in prepregs for the ballistic protection products. In this study an effect of inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS2) in aramid/phenolic resin/PVB composite for improving its viscoelastic and mechanical properties is examined. The effect of IF-WS2 on mechanical properties improvement was first proved by nanoindentation on thin film samples PVB/IF-WS2. The quality of aramid fabrics impregnation with PVB/phenolic resin/IF-WS2, and the nanoparticles dispersion were analyzed by scanning electron microscope with energy dispersive spectrometer. Viscoelastic properties of the composites were examined by dynamic mechanical thermal analysis, observing the storage and loss modulus, mechanical loss factor and glass transition temperature versus temperature and frequency. Time-temperature superposition principle was applied for the construction of master curves. IF-WS2 causes increase of glass transition temperature and improvement in mechanical properties of examined composites.

      PubDate: 2017-05-13T03:59:15Z
  • Radar stealth and mechanical properties of a broadband radar absorbing
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Changxian Wang, Mingji Chen, Hongshuai Lei, Kai Yao, Huimin Li, Weibin Wen, Daining Fang
      A non-magnetic broadband radar absorbing structure (RAS) composed of glass fiber composite and multilayer frequency selective surface (FSS) films was designed, with subsequently optimizing and manufacturing for radar absorbing and mechanical investigations. The results revealed that the proposed RAS exhibited −10 dB absorption from 8 GHz to 18 GHz at thickness of 3.5 mm, with a substantially broadened absorption bandwidth via dual absorption peaks. Due to the embedment of FSS films, the thermal-elastic stability of the structure was slightly enhanced while the flexural and impact resistance performances decreased owing to the effect of weak interface between the FSS films and composite laminates. In fact, the tensile performance of RAS, which was important for application under load bearing conditions, was not significantly compromised. The failure morphologies of the RAS were analyzed by scanning electron microscope (SEM) and the fracture mechanism was discussed.

      PubDate: 2017-05-13T03:59:15Z
  • Performance comparison of NiCo2O4 and NiCo2S4 formed on Ni foam for
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Lv Jinlong, Liang Tongxiang, Yang Meng, Suzuki Ken, Miura Hideo
      Aligned NiCo2S4 nanotubes on Ni foam were obtained by the complete sulfidation of NiCo-precursor which was synthetized by hydrothermal process. The NiCo2S4 nanotubes on Ni foam delivered a higher specific capacitance than NiCo2O4 nanowires on Ni foam. The NiCo2S4 nanotubes on Ni foam exhibited the high capacitance of 1936.2 F g−1 at 1 A g−1. The porous NiCo2S4 nanotubes on Ni foam provided a huge number of exposed active sites for electrochemical reaction. Moreover, the NiCo2S4 nanotubes on Ni foam with large specific surface area facilitated the diffusion and penetration of electrolyte and improved electrochemical reaction. Therefore, after 5000 continuous charge–discharge cycles, only about 7.9% degradation in specific capacitance was observed for NiCo2S4 nanotubes on Ni foam.

      PubDate: 2017-05-13T03:59:15Z
  • Investigation on the seismic retrofit positions of FRP jackets for RC
           frames using multi-objective optimization
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Se Woon Choi
      This research aims to achieve an optimal seismic retrofit method using fiber reinforced polymer (FRP) jackets and to investigate the distributions of retrofit positions and the amount of FRP using the solutions obtained by the proposed method. This method utilizes two objective functions. The first minimizes the amount of FRP reinforcement for economic feasibility, and the second maximizes the spectral acceleration of ground motion that causes the collapse of a structure to reduce the collapse risk. The proposed method is tested on a 3-story reinforced concrete (RC) frame example structure. The amount of FRP used in schemes to retrofit only columns is less than the amount used in schemes to retrofit both columns and beams. In addition, retrofit schemes to differentiate the retrofit level according to the retrofit position are proposed as optimal solutions.

      PubDate: 2017-05-13T03:59:15Z
  • Highly efficient adsorbent based on novel cotton flower-like porous boron
           nitride for organic pollutant removal
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Kakali Maiti, Tran Duy Thanh, Kamaldeep Sharma, David Hui, Nam Hoon Kim, Joong Hee Lee
      Development of highly efficient adsorbent materials for the wastewater treatment is an excellent, cheap, environmental friendly and sustainable approach. Herein, a novel cotton flower-like hierarchically porous boron nitride (BN) structure was successfully synthesized by pyrolizing a boric acid/melamine mixture at 1100 °C in a controlled flow rate ratio of N2/H2. The obtained porous BN material with a large specific surface area (SSA) of 1140 m2 g−1 exhibited high selectivity, fast adsorption rate (∼96% for methylene blue (MB) after 20 min and ∼80% for rhodamine B (RhB) after 10 min) and high adsorption capacities (∼471.2 and 313.4 mg⋅g−1 for MB and RhB, respectively). The excellent selectivity of porous BN material towards dyes adsorption was confirmed from a mixed solution of dye and inorganic salts. In addition, porous BN material remain sustained without losing its adsorption activity even after 10 cycles and exhibited easy regeneration and good reusability which were achieved by a simple heating process. The obtained results indicated that the present porous BN material is a potential candidate for the removal of organic pollutants in water treatment applications.
      Graphical abstract image

      PubDate: 2017-05-13T03:59:15Z
  • Effects of the number of fatigue cycles on the impact behavior of glass
           fiber/epoxy composite tubes
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Memduh Kara, Muhammed Kırıcı
      This paper investigates the impact damage behaviors of filament wound glass reinforced plastic (GFRP) tubes that were fatigued under internal pressure. Damage to the GFRP tubes was investigated, and the tubes' bursting pressures were determined. (±55°)3 E-glass/epoxy composite specimens were manufactured using the filament winding method. Fatigue tests were applied to the specimens at a stress rate of 0.05 and frequency of 0.42 Hz in accordance with the ASTM-D 2992 standard. The specimens were subjected to fatigue tests at a stress level of 35% static burst pressure. Fatigued and non-fatigued composite tube specimens were pre-stressed by applying 32 bar internal pressure. After applying internal pressure, low velocity impact tests at various energy levels (5 J, 10 J and 15 J) were performed on the GFRP tubes. Plots of contact force-time history were obtained. For impact characteristics, such as deflection, absorbed energies were calculated based on the force–time histories. The damaged areas that developed on the specimens were also evaluated. The specimens that fatigued and impacted at the 10 J energy level burst in accordance with the ASTM D 1599 standard. It was concluded that for all of the energy levels employed in this work, as the number of fatigue cycle increases, the rigidity of the tubes decreases.

      PubDate: 2017-05-13T03:59:15Z
  • Mechanical behavior of AZ31/Al2O3 magnesium alloy nanocomposites prepared
           using ultrasound assisted stir casting
    • Abstract: Publication date: 15 August 2017
      Source:Composites Part B: Engineering, Volume 123
      Author(s): Apratim Khandelwal, Karthick Mani, Neeraj Srivastava, Rahul Gupta, G.P. Chaudhari
      Effect of ultrasound-assisted solidification processing on the mechanical behavior of AZ31/Al2O3 magnesium metal matrix nanocomposites (MMNCs) is studied. The melt was subjected to ultrasonic treatment (UST) under two different conditions i.e. UST performed outside the furnace during air-cooling and nearly isothermal UST within the furnace. Different concentrations of alumina nanoparticles (0.5, 1.0, and 2.0 wt%) were used. The significantly improved mechanical behavior of AZ31/Al2O3 Mg MMNCs is explained based on the incorporation of externally added alumina nanoparticles and the in situ reaction of particles with the matrix to form the MgAl2O4 spinel. Results of optical microscopy, SEM and XRD are used to explain the observed enhancement in yield strength and tensile strength. Contribution of different strengthening mechanisms is assessed. Finally, the processing conditions are correlated with ductility of the nanocomposites supported by detailed fractographic analysis.
      Graphical abstract image

      PubDate: 2017-05-13T03:59:15Z
  • Creep behavior of GFRP laminates and their phases: Experimental
           investigation and analytical modeling
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Valentino Paolo Berardi, Michele Perrella, Luciano Feo, Gabriele Cricrì
      Fibre reinforced polymer (FRP) laminates are being currently used within industrial, automotive, naval, aerospace and civil fields. The reliability of composites over time can be evaluated by characterising their deferred behavior. Experimental investigations on this topic are limited due to the complexity in accurate testing. A creep test program was carried out in order to model the viscous behavior of the composites and their phases. Long term behavior of several unidirectional glass fibre reinforced polymer laminates, manufactured through the wet lay-up technique, and their constituent phases (matrix and fibre) is presented in this paper. Starting from the experimental data acquired for six months, a predictive micromechanical model was proposed for the laminates and the fibres, whilst a phenomenological non linear model, formulated by the authors, was used for the resin matrix. The tests were performed at the Structural Engineering Testing Hall of the University of Salerno.

      PubDate: 2017-05-08T08:04:46Z
  • Polymer composites-based thermoelectric materials and devices
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Liming Wang, Yuchen Liu, Zimeng Zhang, Biran Wang, Jingjing Qiu, David Hui, Shiren Wang
      Polymer thermoelectric materials have attracted increasing attention and exhibited great potential in green energy conversion due to their inexpensive to process, lightweight, mechanical flexibility, and intrinsic low thermal conductivity in the past decades. Integration of polymers with nanofillers has been one main approach to tailor the thermoelectric properties of polymers, which not only combines the properties of each component but also displays interesting transport phenomenon induced by the interfaces between polymers and nanofillers. In this review, we discussed the thermoelectric properties of polymer composites, especially for the conducting polymer based composites, including polymer/inorganic, polymer/carbon nanofillers, polymer/polymer hybrids. The fabrication and structure-dependent thermoelectric properties were discussed. In addition, polymer composites based thermoelectric devices were also systematically addressed, and potential issues in the devices fabrication were also analyzed. Regarding the future research opportunities, some visionary discussion was also provided.

      PubDate: 2017-05-08T08:04:46Z
  • Vibration of laminated composite panels and curved plates with different
           types of FGM composite constituent
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Ömer Civalek
      Free vibration analysis of truncated conical panels and annular sector plates with functionally graded materials (FGM) is carried out. Governing equations of motion are obtained based on two different shell theories such as Love's shell theory and first-order shear deformation theory (FSDT). The resulting governing differential equations have been solved using the differential quadrature (DQ) and discrete singular convolution (DSC) methods. As the FGM cases two different material properties of structures are assumed to change continuously in the thickness direction according to the volume fraction power law and the general four-parameter power law distributions in terms of the volume fractions of constituents. Accuracy, convergence and reliability of these two methods have been validated by comparing the obtained results with the existing results available in the open literature. Furthermore, the effects of the grid numbers on results for each method have been also investigated for different boundary conditions and mode numbers for conical panel vibrations. Then, using the DQ and DSC methods, the frequencies values have been calculated for different material and geometric parameters, modes and boundary cases for truncated conical panels with FGM. The effects of material power-law distribution are also discussed. The convergence, advantages and accuracy of the present two methodologies are examined in conjunctions with the vibration problem of truncated conical panels with functionally graded materials (FMG). Some results for annular sector plates and circular cylindrical panels have also been obtained via conical panel equations.

      PubDate: 2017-05-02T09:43:42Z
  • Exact solutions for coupled responses of thin-walled FG sandwich beams
           with non-symmetric cross-sections
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Nam-Il Kim, Jaehong Lee
      In this study, the exact solutions for coupled responses of thin-walled FG (functionally graded) sandwich beams with non-symmetric cross-sections are derived. Material properties of beam are assumed to be graded through the wall thickness of flanges and web. Three types of material distributions are considered. The Euler-Bernoulli beam theory and the Vlasov one are employed for bending and torsional problems, respectively. The explicit expressions for displacement parameters are derived from equilibrium equations based on the displacement state vector consisting of 14 displacement parameters. The exact member stiffness matrix is determined using the force-displacement relations. As a special case, the analytical solutions for decoupled flexural response of FG sandwich beams with various boundary conditions are presented. To demonstrate the accuracy and validity of this study, numerical solutions are presented and compared with results from the finite element method and other available results.

      PubDate: 2017-05-02T09:43:42Z
  • Influences of nanoparticles aggregation/agglomeration on the
           interfacial/interphase and tensile properties of nanocomposites
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Yasser Zare, Kyong Yop Rhee, David Hui
      In this article, the roles of nanoparticles aggregation/agglomeration in the interfacial/interphase and tensile properties of polymer nanocomposites are discussed. The interfacial/interphase and tensile levels are quantitatively characterized in some samples using known models assuming the aggregation/agglomeration phenomena by the effective volume fraction of nanoparticles. The findings show that the nanoparticles aggregation/agglomeration significantly reduces the interfacial/interphase and tensile properties of nanocomposites via decreasing the specific surface area and effective volume fraction of nanoparticles. Additionally, Kerner and Paul models suggest the accurate predictions compared to the experimental data considering the aggregated/agglomerated nanoparticles. However, assumption of well-dispersed nanoparticles over-predicts the modulus in the reported samples.

      PubDate: 2017-04-25T08:30:08Z
  • Numerical analysis of impact failure of automotive laminated glass: A
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Shunhua Chen, Mengyan Zang, Di Wang, Shinobu Yoshimura, Tomonori Yamada
      Laminated glass is a simple sandwiched composite structure, while being widely used in the automotive industry as windshield glazings. It is considered to be safety glass due to its excellent performance in absorbing impact energy and bonding glass fragments. Meanwhile, the impact failure patterns of an automotive windshield glazing contribute to the traffic accident reconstruction. In recent decades, a growing interest has been devoted to the impact failure analysis of automotive laminated glass by means of numerical simulations. The purpose of this work is to present a comprehensive review concerning this aspect. We start by introducing six numerical algorithms for the modeling of the principal damage pattern, glass-ply cracking, followed by the introduction of material models for the plastic interlayer, PVB, and then address three numerical techniques for the adhesion modeling. Three kinds of laminated glass models are summarized. Finally, the performance of the numerical algorithms on the impact failure analysis of laminated glass in terms of glass-ply cracking and acceleration history is thoroughly discussed.

      PubDate: 2017-04-25T08:30:08Z
  • A new process control method for microwave curing of carbon fibre
           reinforced composites in aerospace applications
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Nanya Li, Yingguang Li, John Jelonnek, Guido Link, James Gao
      For the fabrication of carbon fibre reinforced composites used in aerospace industry, microwave curing technologies are more effective than traditional thermal curing technologies. However, the manufacturer's recommended cure cycles used in traditional autoclave curing are directly adopted into current microwave curing technologies without thorough validation. Here, a new cyclic heating and cooling methodology for microwave curing process control of composite is proposed by analyzing mechanisms of heat conduction, stress generation and curing kinetics. The results of the experiment carried out show significant reductions in residual strain, warpage, total curing time and energy consumption, compared with both traditional thermal curing and current microwave curing technologies. The mechanical properties of samples cured by the new process are compared with the autoclave cured ones.

      PubDate: 2017-04-25T08:30:08Z
  • Mechanical characterization of Basalt/epoxy composite laminates containing
           graphene nanopellets
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Mehmet Bulut
      This paper presently investigates the influence of graphene nano-pellets (GnPs) inclusion on mechanical properties (tensile, flexural and impact resistance) of basalt/epoxy composite laminates. Variation of mechanical properties was explained by different GnPs loading by weight ratios (0.1, 0.2 and 0.3 wt %) between epoxy and filler, controlling with full basalt/epoxy laminates (unfilled). Failure characteristics of the prepared samples were also presented and compared along with GnPs filler loadings. Results indicated from this study that incorporation of GnPs fillers at 0.1 wt % significantly enhanced the mechanical properties of basalt/epoxy composites due to high bonding strength at the interphase between GnPs-epoxy-fiber interactions.

      PubDate: 2017-04-25T08:30:08Z
  • The effect of carbon nanotube dispersion on the dynamic characteristics of
           unidirectional hybrid composites: An experimental approach
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Seyyed Mahdi Hosseini Farrash, Mahmoud Shariati, Jalil Rezaeepazhand
      An experimental study on the natural frequencies and damping properties of hybrid composite beams and plates are presented in this paper. Hybrid composites consist of a matrix material along with both nano-fillers and micro fibers. In this research, carbon nanotube (CNT) is used as nano-filler. Epoxy, CNT/epoxy, glass/epoxy, CNT/glass/epoxy, carbon/epoxy and CNT/carbon/epoxy beam-shaped specimens are fabricated. Free vibration analysis of cantilever beams is examined in order to characterize the dynamic behavior of the specimens. 9.4% increase in the fundamental frequency and 12.3% decrease in the damping ratio of the CNT/glass/epoxy beam are observed with respect to those of the glass/epoxy beam specimen. Further, it is observed that CNT/carbon/epoxy beam has degraded fundamental frequency (13.9%) and enhanced damping ratio (31.5%) in comparison with those of carbon/epoxy beam specimen. Moreover, the first bending natural frequencies of the glass/epoxy, CNT/glass/epoxy, carbon/epoxy and CNT/carbon/epoxy plates are obtained experimentally. Plates with all free edges (FFFF) and plates with one edge clamped (CFFF) are investigated. Finite element models confirm the results obtained. Furthermore, the effects of the interfacial adhesion between the CNT/epoxy matrix and micro fibers on the damping properties of the laminated composites are discussed using the obtained results and the scanning electron microscopy (SEM) images.

      PubDate: 2017-04-18T08:20:13Z
  • Spontaneous biaxial pattern generation and autonomous wetting switching on
           the surface of gold/shape memory polystyrene bilayer
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Haibao Lu, Yingzhi Liu, Ben Bin Xu, David Hui, Yong Qing Fu
      In this paper, shape memory effect induced initiation and evolution of surface patterns (wrinkles and cracks) were studied on the surface of gold/shape memory polystyrene (PS) bilayer, alongside with their impacts on autonomous surface wetting effects. Surface wrinkling was generated as a result of in-plane compression in the gold film where the thermal-induced shape memory effect occurred on the foundation layer. Cracks were generated on gold surface when the wrinkle pattern was further developed at a higher strain. The in-plane surface morphological bifurcation was observed when the crack patterns were developed perpendicular to the wrinkles direction, which is induced by biaxial stress transformation within the gold thin film because of the lateral Poisson's effect. The experimental mechanics investigations describe the relationships of the initiation/evolvement of surface morphology upon gold/shape memory PS bilayer with respects to various settings, such as the thicknesses of gold films, the applied strain on polymer layer, etc. The associated impact on surface wetting condition brought by the generated biaxial pattern on gold surface was studied. The water contact angle fluctuates within a narrow range according to the pre-strain for the samples after heating under the same plasma treatment times, which indicates that the biaxial pattern (cracks and wrinkles) in this paper have a little effect on the hydrophobicity of the gold film surface when the heated samples were treated by plasma for same times. After the surface plasma treatment, the surface hydrophilicity of the samples after post-annealing is significantly higher than that of the sample after deposition. And the contact angle decreases steadily as the air plasma treatment time is increased, the controllable surface hydrophobicity of gold coated PS bilayer can be achieved by tuning the plasma treatment time.

      PubDate: 2017-04-18T08:20:13Z
  • Influence of aramid fiber treatment and carbon nanotubes on the
           interfacial strength of polypropylene hierarchical composites
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): P.I. Gonzalez-Chi, O. Rodríguez-Uicab, C. Martin-Barrera, J. Uribe-Calderon, G. Canché-Escamilla, M. Yazdani-Pedram, A. May-Pat, F. Avilés
      The microbond test was used to evaluate the interfacial shear strength (IFSS) of multiscale composites based on a polypropylene (PP) matrix reinforced with aramid fibers (AFs) chemically treated by two methods and coated with multiwall carbon nanotubes (MWCNTs). AFs were treated by two types of acid solutions and coated with oxidized MWCNTs. Scanning electron and atomic force microscopies were conducted to observe the failure modes and correlate the fiber roughness to the IFSS. While both acid treatments caused a small change in fiber roughness, MWCNT deposition largely increased the fiber roughness. The microbond test results indicate that the acid treated fibers exhibited slightly higher IFSS than the untreated fibers and such IFSS is even higher for AFs containing MWCNTs. For chemically treated fibers covered with MWCNTs, a rougher surface with matrix cohesive failure at the edge of the sheared droplet suggests that the IFSS improvement is mainly due to the physicochemical interactions among AF, MWCNT and PP, in addition to mechanical interlocking.

      PubDate: 2017-04-18T08:20:13Z
  • Graphene/carbon nanotube hybrid as a multi-functional interfacial
           reinforcement for carbon fiber-reinforced composites
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Yeon Ju Kwon, Youn Kim, Hyerin Jeon, Sehyeon Cho, Wonoh Lee, Jea Uk Lee
      A graphene/carbon nanotube hybrid material stabilized in an aqueous medium, was coated on carbon fibers by anodic electrophoretic deposition. Chemically oxidized graphene, graphene oxide, was used as a stabilizing agent for dispersion of carbon nanotubes and as a transport medium for the graphene oxide/carbon nanotube hybrid during electrophoretic deposition. This hybrid coating increased the wettability and surface roughness of carbon fibers, which led to improved affinity between the carbon fibers and epoxy matrix. The resulting hybrid-coated carbon fiber-reinforced composites showed an enhancement of over 10% in the short beam strength compared to un-coated carbon fiber composites and demonstrated significantly improved through-thickness electrical conductivity (increase of over 1400%).

      PubDate: 2017-04-18T08:20:13Z
  • Enhancement of electrical conductivity of composite structures by
           integration of carbon nanotubes via bulk resin and/or buckypaper films
    • Abstract: Publication date: 1 August 2017
      Source:Composites Part B: Engineering, Volume 122
      Author(s): Idoia Gaztelumendi, Maialen Chapartegui, Richard Seddon, Sonia Flórez, François Pons, Jacques Cinquin
      This study describes two approaches for the incorporation of carbon nanotubes (CNTs) in carbon fibre reinforced polymer (CFRP) composites, through the addition of the CNTs in the bulk resin and by the addition of CNT-based buckypaper (BP) in the CFRP structure. Several laminates were successfully manufactured integrating these two approaches, where a significant improvement of the electrical conductivity (EC) values was found. Additionally, in order to compare different surface preparations and testing methods, a cross check of EC test was carried out among different laboratories. This characterization was complemented with scanning electron microscopy (SEM) analyses, results of which were used to rule out a complete filtering effect of the CNTs. Furthermore, interlaminar shear strength (ILSS) tests were also performed, with the aim of assessing the mechanical behavior of the different configurations.

      PubDate: 2017-04-18T08:20:13Z
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