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ENGINEERING (1201 journals)                  1 2 3 4 5 6 7 | 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: 14)
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: 207)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 1)
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: 4)
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Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
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Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
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Advances in Remote Sensing     Open Access   (Followers: 34)
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)
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Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access  
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
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: 5)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 6)
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: 8)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 4)
Applied Sciences     Open Access   (Followers: 3)
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)
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Archives of Thermodynamics     Open Access   (Followers: 8)
Arkiv för Matematik     Hybrid Journal  
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: 9)
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: 24)
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: 8)
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: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 40)
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: 14)
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: 4)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 3)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
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: 4)
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: 10)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 13)
City, Culture and Society     Hybrid Journal   (Followers: 20)
Clay Minerals     Full-text available via subscription   (Followers: 8)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 4)
Coastal Engineering     Hybrid Journal   (Followers: 10)
Coastal Engineering Journal     Hybrid Journal   (Followers: 3)
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: 5)
Composite Structures     Hybrid Journal   (Followers: 242)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 175)
Composites Part B : Engineering     Hybrid Journal   (Followers: 215)
Composites Science and Technology     Hybrid Journal   (Followers: 159)
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Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 7)
Control Engineering Practice     Hybrid Journal   (Followers: 40)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 24)
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CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)

        1 2 3 4 5 6 7 | Last

Journal Cover Composites Part B : Engineering
  [SJR: 2.125]   [H-I: 75]   [215 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1359-8368
   Published by Elsevier Homepage  [3041 journals]
  • Thermal response of ceramic matrix nanocomposite cylindrical shells using
           Eshelby-Mori-Tanaka homogenization scheme
    • Abstract: Publication date: 1 June 2017
      Source:Composites Part B: Engineering, Volume 118
      Author(s): B. Sobhaniaragh, R.C. Batra, W.J. Mansur, F.C. Peters
      We find thermal stresses developed in Ceramic Matrix Composite (CMC) cylindrical shells reinforced with aggregated Carbon Nanotubes (CNTs) with heat flux prescribed on the inner surface and temperature on the outer surface. Null surface tractions are prescribed on these two surfaces and the cylinder edges are clamped. The material properties are homogenized by using a two-parameter Eshelby-Mori-Tanaka (EMT) approach. Material properties of the ceramic are assumed to depend upon the temperature, and the smooth variation of the CNT volume fraction through the shell thickness is assumed to be described either by a sigmoidal function or profile-O or profile-X often used in the literature. The one-way coupled thermo-mechanical problem is analyzed by first numerically solving the nonlinear heat equation with the Generalized Differential Quadrature Method (GDQM), and then the linear mechanical problem by using Reddy's Third-order Shear Deformation Theory (TSDT) and the GDQM. For the same thermal boundary conditions and the volume fraction of CNTs, the maximum hoop, the in-plane shear and the transverse normal stresses developed in the cylinder are highest for the profile-X of CNTs. The aggregation factor noticeably influences the maximum transverse normal and the maximum hoop stresses developed in the cylinder.

      PubDate: 2017-03-21T10:34:30Z
  • Effect of mechanical states on water diffusion based on the free volume
           theory: Numerical study of polymers and laminates used in marine
    • Abstract: Publication date: 1 June 2017
      Source:Composites Part B: Engineering, Volume 118
      Author(s): T. Peret, A. Clement, S. Freour, F. Jacquemin
      The humid aging of composite materials is often interpreted assuming a constant diffusivity and most particularly independent on the mechanical fields. However, some experimental investigations highlight a coupling between the mechanical fields and the water diffusion in polymer based materials. In this work, this hygro-mechanical coupling is implemented through the semi-empirical free volume theory. The transient coupled problem is numerically studied using the classical finite element method. The problem is solved with the commercial code Abaqus©. Three numerical examples, emphasizing the interest of using such models in the investigation of the aging of composites, are presented. In the two first cases, the aging of pure resin specimen, under mechanical loading, is analyzed. In the last instance, the impact of the stiff reinforcements, assumed hydrophobic, on the water absorption behavior of an uni-directional laminate is studied.

      PubDate: 2017-03-21T10:34:30Z
  • PBO mesh mobilization via different ways of anchoring PBO-FRCM
    • Abstract: Publication date: 1 June 2017
      Source:Composites Part B: Engineering, Volume 118
      Author(s): Tomasz Trapko, Michał Musiał
      This paper describes different ways of anchoring reinforcements made of PBO fibre mesh and improving their adhesion to concrete. Strengthening effectiveness and PBO-FRCM reinforcement mobilization were assessed on the basis of 12 models of strengthened RC beams. The beams were divided into two groups depending on the compressive strength of their concrete. Three ways of anchoring the PBO mesh were used in each of the groups. In type-A beams stirrups were made at the ends of the longitudinal reinforcement. In type-B beams the ends of the longitudinal reinforcement were wound on composite rods and bonded into transverse cuts at the ends of the beams. In type-C beams the longitudinal reinforcement was covered along its entire length with a layer of flexible mortar. The research to date shows that the improvement of the anchorage of the PBO mesh ends is of key importance for elements subjected to bending, shearing or compression. In this paper the behaviour of the beams under load is described on the basis of an analysis of their deflections. The distributions of strains in the longitudinal reinforcement depending on the beam type are shown. Attention is drawn to the redistribution of stress in the longitudinal reinforcement at the instant when the elements crack. The degrees to which the PBO mesh is mobilized depending on the way of anchoring the PBO-FRCM reinforcement were investigated.

      PubDate: 2017-03-21T10:34:30Z
  • Multiscale failure analysis of periodic masonry structures with
           traditional and fiber-reinforced mortar joints
    • Abstract: Publication date: 1 June 2017
      Source:Composites Part B: Engineering, Volume 118
      Author(s): Fabrizio Greco, Lorenzo Leonetti, Raimondo Luciano, Patrizia Trovalusci
      In this paper, a novel adaptive multiscale model is proposed for accurately predicting the nonlinear mechanical response of periodic brick masonry due to crack initiation and propagation under general in-plane loading histories. Such a model relies on a two-level domain decomposition technique, used in conjunction with an adaptive strategy able to automatically zoom-in the zones incipiently affected by damage localization, with the aim of reducing the typically high computational effort associated with fully microscopic models. The proposed switching criterion is based on the numerical determination of microscopically informed first failure surfaces taking into account higher-order deformation effects. In order to assess the validity of the proposed strategy, a sensitivity analysis is carried out on a shear wall sample by varying the required input numerical parameters. An additional application of the proposed multiscale model is then presented for investigating the role of the fiber content in fiber-reinforced mortars (FRMs), recently introduced for masonry construction and rehabilitation, on the overall response of a deep beam sample.

      PubDate: 2017-03-21T10:34:30Z
  • Pantographic lattices with non-orthogonal fibres: Experiments and their
           numerical simulations
    • Abstract: Publication date: 1 June 2017
      Source:Composites Part B: Engineering, Volume 118
      Author(s): Emilio Turco, Maciej Golaszewski, Ivan Giorgio, Francesco D'Annibale
      Current research in metamaterials design is pushing to fill the gap between mathematical modelling and technological applications. To meet these requirements predictive and computationally effective, numerical tools need to be conceived and applied. In this paper, we describe the performances of a discrete model based on the microstructure architecture [1] and those of a second gradient continuum model [2] for pantographic structures with non-orthogonal fibres comparing them with some experimental results. The interest in these structures resides in the exotic behaviour that they have already shown [3] and their study seems promising. The comparison which we present here shows that, depending on the length scale characterising the structural cell of pantographic sheets, either discrete or continuum model performance and/or behaviour may prevail. Some homogenization interesting problems are listed in the conclusions in the hope that they may be rigorously studied with the most advanced mathematical tools.

      PubDate: 2017-03-16T14:13:11Z
  • Dynamic stability analysis of a pressurized FG-CNTRC cylindrical shell
           interacting with supersonic airflow
    • Abstract: Publication date: 1 June 2017
      Source:Composites Part B: Engineering, Volume 118
      Author(s): Hamed Asadi, Quan Wang
      The objective of this research is to investigate the aeroelastic buckling and flutter instability of a pressurized functionally graded carbon nanotube reinforced composite (FG-CNTRC) cylindrical shell subjected to supersonic airflow. The dynamic model of the FG-CNTRC cylindrical shell is established in accordance with the first-order shear deformation theory, Donnell kinematic theory along with the von Karman geometrical nonlinearity. The quasi-steady Krumhaar's modified piston theory by considering the effect of the panel curvature is used to estimate the aerodynamic pressure induced by the supersonic airflow. The dynamic equations are discretized using trigonometric expansion through the circumferential direction and harmonic differential quadrature (HDQ) method through the meridional direction. Effects of boundary conditions, geometrical parameters, volume fraction and distribution of CNTs and the Mach number on the flutter instability, onset of the buckling and deformation shapes of the cylindrical shell are put into evidence through a set of parametric studies. The simulation indicates that the critical flutter dynamic pressure may be significantly enhanced through functionally graded distribution of CNTs in a polymer matrix. Furthermore, it is found that presence of the aerodynamic pressure may completely change deformation shapes of the FG-CNTRC cylindrical shell.

      PubDate: 2017-03-16T14:13:11Z
  • Holes, cracks, or inclusions in two-dimensional linear anisotropic
           viscoelastic solids
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Van Thuong Nguyen, Chyanbin Hwu
      By combining the elastic-viscoelastic correspondence principle with the analytical solutions of anisotropic elasticity, the problems of two-dimensional linear anisotropic viscoelastic solids can be solved directly in the Laplace domain. After getting the solutions in the Laplace domain, their associated solutions in real time domain can be determined by numerical inversion of Laplace transform. Following this general adopted process, the problems of holes, cracks, or inclusions in two-dimensional linear anisotropic viscoelastic solids, which appear frequently in polymer matrix composites and cannot be solved directly by the commonly used commercial finite elements, are solved in this paper. Here, the hole can be elliptical or polygon-like; the crack can be a single crack, or two collinear cracks, or an interface crack; and the inclusion can be rigid, elastic or viscoelastic. The loads considered include the uniform load at infinity, and the point force applied at the arbitrary location. The solution of the point force is then employed as the fundamental solution of boundary element method which is used for further comparison of the analytical solutions. The accuracy and efficiency of the presented solutions are illustrated through four representative numerical examples which involve four isotropic viscoelastic and two anisotropic viscoelastic materials.

      PubDate: 2017-03-16T14:13:11Z
  • Effect of nano-CaCO3 slurry on the mechanical properties and
           micro-structure of concrete with and without fly ash
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Tao Meng, Yue Yu, Zhongjia Wang
      The effect of nano-CaCO3 slurry on the mechanical properties and microstructure of concrete with and without fly ash was studied in this paper. Experimental results showed that nano-CaCO3 slurry was helpful to increase the mechanical strength of concrete with and without fly ash at early ages due to the acceleration of cement hydration from seeding effect and the more compact microstructure of cement paste from nano-filling. However, the efficacy of nano-CaCO3 slurry on the concrete without fly ash was quite limited at the late ages just like other nano-materials. This may well affect the application of nano-materials in concrete. On the other hand, nano-CaCO3 slurry was still helpful to enhance the mechanical strength of concrete with fly ash at late ages. Furthermore, the enhancement degree of mechanical strength of concrete with fly ash at 56 days increased with the increasing content of fly ash when 2% fly ash was substituted by nano-CaCO3. The results of X-Ray diffraction analysis and SEM observation indicated that the pozzolanic reaction degree of fly ash could be accelerated by nano-CaCO3 slurry at late ages. Therefore, a feasible technique for the usage of composite nano-materials in concrete may well be provided by using nano-CaCO3 with fly ash due to the acceleration hydration of cement at early ages and that of fly ash at late ages.

      PubDate: 2017-03-16T14:13:11Z
  • Dimensional accuracy analysis of coupled fused deposition modeling and
           vapour smoothing operations for biomedical applications
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Jasgurpreet Singh Chohan, Rupinder Singh, Kamaljit Singh Boparai, Rosa Penna, Fernando Fraternali
      Fused Deposition Modeling (FDM) is one of the most extensively used Additive Manufacturing technique which has substantially shortened the product development time and cost. The application has been extended to fabricate biomedical implants through investment casting process. But the FDM replicas exhibit poor surface quality which requires further post finishing. Thus, it is very difficult to achieve adequate dimensional accuracy as surface finishing techniques resulted in material removal and erosion of upper surface. The vapour smoothing is an advanced finishing technique which eliminates tool-workpiece contact and yield ultra smooth finish but dimensional accuracy of FDM replicas is yet to be ascertained. In present research, the efforts are made to explore the influence of FDM and VS process parameters in dimensional features of complex designs. The influence of six parameters on radial (head diameter) and linear dimensions (neck and stem thickness) is studied using Taguchi orthogonal array. The CMM measurements showed shrinkage in head diameter while positive deviation has been observed in linear dimensions before vapour smoothing with maximum impact of orientation angle. The vapour smoothing process caused shrinkage in both linear and radial dimensions with maximum effect of smoothing time. The process parameters and their levels are optimized and confirmatory experiments indicated reduced deviations in dimensional features with consistency in IT grades.

      PubDate: 2017-03-16T14:13:11Z
  • Compression property of a novel lattice sandwich structure
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Yang Liu, Changyu Zhou, Bo Cen, Zhuo Zeng, Xiaofeng Lu, Xiaolei Zhu
      In order to get a strong, stiff and lightweight structure, a novel glass fiber reinforced composite (GFRC) lattice sandwich panel (LSP) was designed and manufactured. The lattice core consists of orthogonal corrugated GFRC truss and foam cubes. A modified vacuum assisted resin infusion (VARI) method was used to manufacture the LSP. Flatwise compression test, theoretical analysis and finite element analysis were carried out to reveal the modulus and failure modes of the structure. A local buckling failure and delamination at the corner of strut were observed in compression. Experimental, theoretical and simulation result show great agreement with each other on the modulus of the structure. The experimental modulus and ultimate failure strength are about 1.798 GPa and 5.59 MPa, respectively.

      PubDate: 2017-03-16T14:13:11Z
  • In situ intercalation polymerization approach to polyamide-6/graphite
           nanoflakes for enhanced thermal conductivity
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Fanbin Meng, Fei Huang, Yifan Guo, Jingjing Chen, Xiangnan Chen, David Hui, Ping He, Xuesong Zhou, Zuowan Zhou
      Traditional polymer composites generally present limited thermal conductivity (TC) even highly loaded with highly thermally conductive fillers due to the lack of large interfacial thermal resistance between the fillers and the surrounding polymers. In this work, polyamide-6/graphite nanoflakes (PA6/GnF) composites with high TC can be obtained through a one-step in situ intercalation polymerization. The caprolactam onium ion (CL⊕) catalysted by 6-aminocaproic acid can effectively intercalate into the interlayer of expanded graphite (EG) and lead to the separation of EG into GnF after in situ polymerization. Thereafter the homogeneous dispersions of GnF with ordered arrangement and strong interfacial interactions between PA6 and GnF can be formed within the PA6/GnF composites, which can favor the formation of the consecutive thermal conductive pathways or networks at a relatively low EG loading. The obtained composites, at only EG loading of 12 wt%, exhibit a high TC (2.49 W/mK), corresponding to an enhancement of 678% compared to that of neat PA6. This strategy offers new insights into the fabrication of graphene based composites, and provides a straightforward and highly industrializable process for fabrication of high-performance GnF-based thermally conductive composites.
      Graphical abstract image

      PubDate: 2017-03-16T14:13:11Z
  • Effective shear modulus of solids reinforced by randomly
           oriented-/aligned-elliptic nanofibers in couple stress elasticity
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Hossein M. Shodja, Bita Alemi
      Nowadays, by adding a small amount (about 0.5–5% by weight) of a desired nanomaterial to a matrix having certain properties one may design a multifunctional nanocomposites with a remarkably improved macroscopic properties of interest. The capability of conventional continuum theories in treating the problems of embedded ultra-small inhomogeneity with any of its dimensions comparable to the characteristic lengths of the involved constituent phases is questioned, mainly, on the grounds of the accuracy and the size effect. The micromechanical framework based on the Eshelby's ellipsoidal inclusion theory [1] which has been widely used to estimate the overall behavior of composites falls under the same category, as is size insensitive. In this work, effort is directed at the prediction of the macroscopic shear modulus of composites consisting of nano-/micro-size fibers of elliptic cross-sections via couple stress theory, a physically realistic theory that encompasses the size effect. To this end, the fundamental equations of couple stress elasticity in elliptic coordinates are derived and several fundamental elliptic inhomogeneity problems in plane couple stress elasticity are solved analytically. For the purpose of the application of these results to the study of the effective properties of the composites of interest, Mori and Tanaka theory [2] is first reformulated in the mathematical framework of couple stress theory. Subsequently, the overall shear modulus of solids reinforced by aligned as well as randomly oriented elliptic nanofibers will be predicted. The influences of the size, shape, orientation, rigidity, and intrinsic length of the reinforcing nanofibers as well as the effects of the characteristic length of the matrix on the effective shear modulus of the composite are addressed.

      PubDate: 2017-03-16T14:13:11Z
  • An improved spring method for calculating the load distribution in
           multi-bolt composite joints
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Jinwu Xiang, Shiwei Zhao, Daochun Li, Yining Wu
      Fast and reliable prediction of the load distribution is necessary in the initial design of the composite bolted joint structures. Traditional spring method is time consuming in the modelling of a composite bolted joint structure. In this paper, an improved spring method considering the hole clearance and friction effects is developed for efficient modelling of the composite bolted joint structures. This method is based on spring method and finite element theory. A seven-bolt double-lap joint model is built as an example to study the effects of plate width, plate thickness, bolt pitch and clearances on the load distribution. The improved spring method is also adopted in the Monte Caro simulation with clearances considered as uncertain-but-bounded parameters. The results show that the proposed method is time efficient for the load distribution prediction of the bolted joint composite structures.

      PubDate: 2017-03-09T01:23:46Z
  • Nonlinear low-velocity impact analysis of matrix cracked hybrid laminated
           plates containing CNTRC layers resting on visco-Pasternak foundation
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Yin Fan, Hai Wang
      This paper investigates the low-velocity impact response of a shear deformable laminated plate which contains both carbon nanotube reinforced composite (CNTRC) layers and fiber reinforced composite (FRC) layers. The effect of matrix cracks is considered and a refined self-consistent model (SCM) is selected to describe the degraded stiffness of the plate. The material properties of both FRC layers and CNTRC layers are assumed to be temperature-dependent. The plate rests on a visco-Pasternak foundation in thermal environments. A modified Hertz model is utilized to describe the contact force between the impactor and the plate. Based on a higher order shear deformation theory and von Kármán nonlinear strain-displacement relationships, the motion equations of the plate are established and solved by means of a two-step perturbation approach. The effects of the crack density, CNT volume fraction, temperature variation and the foundation stiffness on the nonlinear low-velocity impact response of hybrid laminated plates with multiple matrix cracks are discussed in detail.

      PubDate: 2017-03-09T01:23:46Z
  • Investigating the suitability of roughness parameters to assess the bond
           strength of polymer-metal hybrid structures with mechanical adhesion
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Tobias Kleffel, Dietmar Drummer
      The joining of distinct incompatible materials, like metals and polymers or fiber-reinforced polymers, is gaining in importance, especially for lightweight applications. Here, it is advantageous if the materials can be joined during the manufacturing of the hybrid component. Besides conventional technologies, like over-molding or the use of adhesive bonds, the use of micro structures is a promising approach for in-mold assembly. However, the characterization of these micro structures to assess the bond strength is difficult, especially for a load perpendicular to the joining surface. This paper deals with the assessment of the bond strength of polymer-metal hybrid structures with micro-structured metal inserts by the use of roughness parameters. The micro structures were produced by electrochemical treatments.

      PubDate: 2017-03-09T01:23:46Z
  • Improving flexural performance of ultra-high-performance concrete by
           rheology control of suspending mortar
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Weina Meng, Kamal Henri Khayat
      This study develops a rheology control method to improve steel fiber distribution and flexural performance of ultra-high-performance concrete (UHPC) by adjusting the rheological properties of the suspending mortar of UHPC before steel fibers are added. Correlations among the plastic viscosity of the suspending mortar, the resulting steel fiber distribution, and flexural properties of UHPC are established. This was done by changing the dosage of viscosity modified admixture (VMA) for investigated UHPC mixtures. The optimal plastic viscosity of the suspending mortar that allows for the optimized fiber distribution and flexural performance of UHPC is determined. The plastic viscosity is correlated with the mini V-funnel flow time, which provides a simple alternative to evaluate the plastic viscosity. For a UHPC mixture with 2% micro steel fibers, by volume, the optimal mini V-funnel flow time of suspending motar was determined to be 46 ± 2 s, which corresponded to the optimal plastic viscosity (53 ± 3 Pa s) that ensures the greatest fiber dispersion uniformity and flexural performance of UHPC. However, increasing the VMA dosage retarded the hydration kinetics and reduced the degree of hydration, compressive strength, and the bond properties of the fiber-matrix interface of UHPC.

      PubDate: 2017-03-09T01:23:46Z
  • Effect of hollow glass microsphere (HGM) on the dispersion state of
           single-walled carbon nanotube (SWNT)
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): DongHo Kang, Sung Wook Hwang, Bich Nam Jung, Jin Kie Shim
      Single-walled carbon nanotube (SWNT) loaded polypropylene (PP) based syntactic foam is fabricated by melt mixing method. In order to evaluate the effect of hollow glass microsphere (HGM) on the dispersion state of SWNT and to identify the optimal weight of HGM, various analysis is performed. Based on the comprehensive result analysis, it is concluded that HGMs weight between 1 and 7 wt% shows the best performance. At low weight of HGMs (0.1–0.5 wt%), HGMs act as nucleating agent to escalate the agglomeration of SWNT, while high load of HGMs tend to aggregate each other, hindering the formation of SWNT percolation network.

      PubDate: 2017-03-09T01:23:46Z
  • Synthesis & chemical and dielectric characterization of poly (linoleic
           acid)-g-poly (dimethylaminoethyl methacrylate): A novel high-κ graft
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Mert Yıldırım, Abdulkadir Allı, Gülnur Önsal, Neslihan Gök, Oğuz Köysal
      In this study, poly (linoleic acid)-g-poly (dimethylaminoethyl methacrylate) (PLina-g-PDMA; PLDMA) graft copolymer was obtained from polymeric linoleic acid peroxide (PLina) possessing peroxide groups in the main chain by free radical polymerization of 2-dimethylaminoethyl methacrylate (DMA). Synthesized graft polymer, i.e. PLDMA, was first characterized chemically through proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) and elemental analysis (EA) techniques. Later, PLDMA was injected into ITO coated glass cell and its electrical and dielectric measurements were carried at room temperature between 3 Hz and 3 MHz. PLDMA revealed dielectric constant (ε′) values on the order of 103 below 1 kHz. Therefore, having such high dielectric constant value, PLDMA was proposed as high-κ dielectric material with ε′ = 6141 at 3 Hz. Dielectric relaxation of the polymer was characterized using Cole-Cole plots. Investigation of electrical conductivity of PLDMA yielded dc conductivity as 36774 S/cm. Moreover, PLDMA was further dispersed with CdTe quantum dots to explore its utility for hybrid composites and effects of quantum dot dispersal on electrical and dielectric parameters were also investigated.
      Graphical abstract image

      PubDate: 2017-03-09T01:23:46Z
  • Study of damage evolution in composite materials based on the
           Thermoelastic Phase Analysis (TPA) method
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Davide Palumbo, Rosa De Finis, Giuseppe Pompeo Demelio, Umberto Galietti
      Standards and conventional procedures used for analysing fatigue damage in composite materials involve high experimental campaign costs due to time-consuming tests. This aspect becomes relevant for large structures where the cost of experimental setup tends to rise according to structure dimensions. In this regard, in recent years, efforts to produce fatigue characterisation of materials have made use of several experimental techniques, i.e. thermographic techniques. Most of these, however, refer to Standard specimens and laboratory equipment and set-up. Through the use of Thermography, in this work a new procedure has been developed which is capable of monitoring damage in GFRP composite material. The analysis of thermal signal in the frequency domain allows for the isolation of indexes which are related to the thermoelastic and dissipative heat sources. In particular, the phase of thermoelastic signal, associated with intrinsic dissipation processes occurring in the material, has been used to localize and assess the damaged areas in a quantitative manner. Moreover, the thermoelastic phase analysis leads to an evaluation of the endurance limit of composites. In fact, by comparing the results with those provided by the standard test methods, the potential has been shown of the proposed procedure firstly as a non-destructive technique for continuous monitoring of damage in composite structures undergoing fatigue loadings, and secondly, as a fatigue limit index.

      PubDate: 2017-03-09T01:23:46Z
  • The effect of mechano-chemical activation and surface treatment of
           limestone filler on the properties of construction composites
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Anja Terzić, Dragan Radulović, Lato Pezo, Ljubiša Andrić, Ljiljana Miličić, Jovica Stojanović, Irena Grigorova
      The effect of the combined actions of milling and hydrophobization procedures applied in construction composites synthesis was investigated. The mortars were prepared with cement (CEM I 42.5) and calcite aggregate complying the standard 1:3 mix ratio. The limestone filler (10 wt%) was added to the mixture upon its mechano-chemical activation in an ultra-centrifugal mill. The activation variables (milling time, rotor velocity, sieve mesh size) were altered to achieve the optimal quality of the powder. The treatment was optimized via chemometric tools. The r2 values (0.955–0.998) of second order polynomial models accurately predicted the output and the Standard score analysis chose the optimal activation parameters: 4.25 min; 48.58 m/s and 80 μm sieve. The selected filler and all three aggregate fractions were coated with stearic acid via dry procedure. The mortar mixes, prepared with uncoated (M1) and coated (M2) aggregate and filler, were cured for a period of 28 days during which compressive strength and water absorption were monitored. The dimensional changes in mortars were estimated via TMA dilatometer measurements. Thermo-analytical methods (DTA/TGA) were applied in the thermal behavior analysis. Mineralogical and morphological changes in the structure of hardened composite were detected by XRD and SEM, respectively. Limestone aggregate led to lower final compressive strengths in mortar, but it produced an infinitesimally small shrinkage at 1000 °C. The hydrophobization via stearic acid initiated the decrease in water absorption and formation of needle-like micro-network that filled structural voids reducing open porosity. The assessment of the effects of limestone utilization as a filler and as an aggregate on the mortar performances confirmed that this novel water-repellent composite is applicable in structural design.
      Graphical abstract image

      PubDate: 2017-03-09T01:23:46Z
  • Nonlinear dynamic thermoelastic response of rectangular FGM plates with
           longitudinal velocity
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Yan Qing Wang, Jean W. Zu
      This study investigates nonlinear dynamic thermoelastic response of functionally graded material (FGM) plates with longitudinal velocity for the first time. The large amplitude motion of FGM plates is considered so that the present model includes both geometry and material nonlinearities. Based on the D'Alembert's principle, the out-of-plane equation of motion of the system is obtained by considering the thermal effect and the longitudinal velocity. After that, the Galerkin method is employed to discretize the partial differential equation of motion to a set of ordinary differential equations. The method of harmonic balance is used to solve analytically the time-varying set of ordinary differential equations. The approximately analytical solutions are verified by numerical solutions utilizing an adaptive step-size fourth-order Runge-Kutta technique. Furthermore, the stability of steady-state response is analyzed for the approximately analytical solutions. The linear frequency characteristics and nonlinear frequency-response characteristics are both presented for the system. The nonlinear frequency-response relationships demonstrate strong hardening-type behavior of the system. Results are shown to examine the influences of different parameters including longitudinal velocity, temperature, constituent volume distribution, in-plane pretension, damping and force amplitude on the nonlinear dynamic thermoelastic response of FGM plates with longitudinal velocity.

      PubDate: 2017-03-09T01:23:46Z
  • Low velocity impact performance of stitched flax/epoxy composite laminates
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): M. Ravandi, W.S. Teo, L.Q.N. Tran, M.S. Yong, T.E. Tay
      This paper presents an experimental investigation of the effect of through-thickness natural fibre stitches on the low-velocity impact response of the woven flax/epoxy composite laminates with the purpose of extending their use to higher performance applications. Two impact energy levels were selected to produce a perforated and a non-perforated damage state in stitched/unstitched composites for study. Twistless flax yarn and twisted cotton thread were used to stitch at an equivalent stitch areal fraction for all laminates of the same thickness. Unstitched cross-plies [0/90]4s of continuous flax fibres were also manufactured at a similar thickness for benchmarking of energy absorption and fracture mechanisms. Comparison of the damage sustained in the unstitched and stitched natural fibre composites showed that while delamination was not the predominant damage mode in both laminates, stitching does facilitate the propagation of in-plane cracks. The experimental findings revealed that stitching with thicker yarn (Flax) led to a lower ratio of absorbed energy per area of damage as well as energy absorbed for full penetration.

      PubDate: 2017-03-09T01:23:46Z
  • Enhanced hydrogen gas barrier performance of diaminoalkane functionalized
           stitched graphene oxide/polyurethane composites
    • Abstract: Publication date: 15 May 2017
      Source:Composites Part B: Engineering, Volume 117
      Author(s): Parthasarathi Bandyopadhyay, Thanh Tuan Nguyen, Xuyang Li, Nam Hoon Kim, Joong Hee Lee
      We report the simultaneous reduction, surface modification, and stitching of graphene oxide (GO) by ethylenediamine (EDA) and triethylenetetramine (TET) to boost the hydrogen gas barrier performance of polyurethane (PU) composite-coated nylon films. TEM and XRD analyses confirmed the formation of stitched EDA-modified GO (EDA-mGO) and TET-modified GO (TET-mGO) while FT-IR spectroscopy, Raman spectroscopy, and thermogravimetric analyses revealed the functionalization and reduction of GO by EDA and TET. EDA-mGO/PU and TET-mGO/PU composites were synthesized using different amounts of EDA-mGO and TET-mGO, respectively, and composites were deposited onto surface modified nylon films by spray coating to prepare hydrogen barrier films. FTIR, XRD, and FESEM analyses showed that both EDA-mGO and TET-mGO were uniformly dispersed into PU matrix. Cross-sectional FESEM showed strong adhesion between the nylon and composites. Coated films exhibited dramatic reduction in hydrogen gas transmission rate (H2GTR) and TET-mGO/PU with 22 wt% TET-mGO exhibited 93% decrease in H2GTR than bare nylon film.
      Graphical abstract image

      PubDate: 2017-03-09T01:23:46Z
  • Fracture-toughness/notch-sensitivity correlation for metal- and
           ceramic-based fibrous composites
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): S.T. Mileiko
      The fracture toughness of a material is given by the critical stress intensity factor K IC used in linear fracture mechanics to evaluate the ultimate load on a structural element containing a crack-like defect. However, K IC can hardly be applicable to the failure analysis of elements made of fibrous composites. Hence, an apparent value of the critical stress intensity factor, K*, for composites are normally experimentally measured to evaluate only the damage tolerance of composite materials. The measurements of the ratio of the flexural strength of specimens with and without a notch (σN/σ0) serve the same purpose. The analysis of K* and σN/σ0 data obtained by testing various oxide/molybdenum composites as well as those for oxide/oxide and C-fibre/SiC-matrix composites published recently along with older data for boron/aluminium reveals a linear correlation between these two characteristics of composites.

      PubDate: 2017-03-03T15:23:25Z
  • Reduced graphene oxide-carbon nanotube grown on carbon fiber as
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Chuanyin Xiong, Tiehu Li, Tingkai Zhao, Alei Dang, Hao Li, Xianglin Ji, Wenbo Jin, Shasha Jiao, Yudong Shang, Yonggang Zhang
      In this work, reduced graphene oxide (RGO) - carbon nanotubes (CNT) grown on carbon fiber (CF) is fabricated by a combination of electrophoretic deposition (EPD) and chemical vapor deposition (CVD). Firstly, CF-GO composite is prepared via EPD. Secondly, the CF-RGO-CNT hybrid is obtained by floating catalyst chemical vapor deposition method for synthesizing CNT on the CF-RGO substrate. The as-prepared three-dimensional (3D) hierarchical hybrid shows strong mechanical stability and high flexibility at various bending angles. Furthermore, the hybrid is characterized by scanning electron microscope, X-ray Diffraction and Raman spectroscopy, and its supercapacitor properties are also tested. The electrochemical measurements display a higher specific capacitance of 203 F g−1, 4 times higher than that of pure CF. Importantly, the hybrid shows high electrochemical stability at various bending angles, and can be directly served as flexible electrode with binder-free for high-performance supercapacitors. All these attractive results indicate that the as-prepared 3D hybrid is a promising candidate for flexible supercapacitor applications.
      Graphical abstract image

      PubDate: 2017-03-03T15:23:25Z
  • Durability characteristics and property prediction of glass fibre
           reinforced mixed plastics composites
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Rohan Muni Bajracharya, Allan C. Manalo, Warna Karunasena, Kin-tak Lau
      This paper presents an experimental and theoretical studies of the durability of composite materials made from mixed plastic solid waste (PSW) containing high-density polyethylene, low-density polyethylene, polypropylene and short glass fibres (10–30% by weight). The effects of exposure to elevated temperatures, UV radiation and moisture ingression were the main parameters considered. The results showed that the exposure to a temperature of 60 °C or higher weakens the adhesion of the glass fibre due to the softening of the mixed PSW and resulting in reduced mechanical properties. Furthermore, exposure to UV radiation results in the shrinkage of the specimens improving the interfacing bonding whereas exposure to moisture results in the swelling of the specimens weakening the interfacial bonding. Besides, the addition of glass fibre reduces the surface degradation of composites under UV and moisture ingression resulting in higher matrix properties. For design purposes, a single equation based on modified rule of mixture was developed to predict the tensile modulus and strength of these composites by introducing environmental factors accounting the effects of different exposure conditions.
      Graphical abstract image

      PubDate: 2017-03-03T15:23:25Z
  • An investigation of dynamic failure progress and properties of 2D C/SiC
           composite from 173 K to 1273 K by SHTB
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Xuan Chen, Chao Chen, Li Cheng, Wei Chen
      Our work studies the dynamic properties of coated and uncoated 2D C/SiC composite material from 173 K to 1273 K by means of Split Hopkinson Tensile Bar. Examination of the failure process of the specimen by SIM D8 ultra high-speed camera and damage analysis help define the three phases of crack propagation, namely: the elastic pre-damaged phase, the yielding phase or the crack-initiating phase, and the failure phase or the phase of fast-spreading cracks. Experimental results also reveal that the dynamic tensile strength of both coated and uncoated composites decreases with the increase of temperature and decreases more conspicuously at higher temperature. An SEM is employed to examine the fracture surface and damage of C/SiC composites at different temperatures are determined by calculation. Finally, k was introduced according to the Cowper-Symonds fitting model to describe the temperature dependency. This implies a greater significance of SiC coating on the properties of the composite with the increase of temperature. Thus, it is believed that coated composite within the temperature range of 173 K–1273 K displays a superior impact property compared with uncoated composite, and is a better structural thermal protection material.

      PubDate: 2017-03-03T15:23:25Z
  • Investigating process-structure relations of ZnO nanofiber via
           electrospinning method
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Ehsan Ghafari, Yining Feng, Yao Liu, Ian Ferguson, Na Lu
      1D ZnO nanofibers were fabricated in this study using the electrospinning method through sol-gel approach. The effects of fabrication processing parameters on the nanofibers size have been systematically investigated. The higher concentration of the polymer resulted in a broader distribution of the nanofibers diameter due to non-uniform ejection of the fluid jet. The results indicated that an increase in annealing temperature resulted in a lower diameter size and more uniformity of the nanofiber due to decomposition of PVA. The DSC result confirms that an annealing temperature higher than 480 °C is required to remove the PVA and fully decompose the zinc acetate to form crystalline ZnO nano structure. The presence of a crystal ZnO phase was further confirmed by TGA, XRD, FTIR and PL analysis.

      PubDate: 2017-03-03T15:23:25Z
  • Recycling of non-metallic automotive shredder residues and coal fly-ash in
           cold-bonded aggregates for sustainable concrete
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): F. Colangelo, F. Messina, L. Di Palma, R. Cioffi
      In order to achieve the relevant objectives of EC directive on end-of-life of vehicles (2000/53/CE), innovative solutions such as recycling automotive shredder residues are required. This paper deals with the design and characterization of concrete mixtures containing artificial aggregates obtained through the cold-bonding pelletization of non-metallic fraction of automotive shredder residues, commonly named car fluff. In this work, car fluff was pelletized with blended cementitious mixtures containing coal fly ash, another industrial by-product. Produced artificial aggregates were characterized by determining main environmental, physical and mechanical properties. Then, they were employed as lightweight aggregates for manufacture of sustainable concrete. Experimental results showed good mechanical properties of concrete containing these aggregates and leaching behaviour of hardened specimens confirmed the environmental effectiveness of the here studied car fluff recovery process.

      PubDate: 2017-03-03T15:23:25Z
  • Study of melting properties of basalt based on their mineral components
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Xingfen Chen, Yunsheng Zhang, David Hui, Meirong Chen, Zhishen Wu
      In this paper, the mineral components, initial liquid temperature, melting temperature, melting process, and melt homogeneity of andesite, andesitic basalt, tholeiite basalt, and alkali basalt are investigated. The results show that the basalts exhibit initial liquid temperatures and melting temperatures in the following descending order: andesite, andesitic basalt, tholeiite basalt, and alkali basalt. The initial liquid temperature and melting temperature of the basalts increase with an increase in quartz and plagioclase (anorthite and albite) content, but they decrease with an increase in pyroxene (diopside and hypersthenes) content. In the melting process of basalt, the mineral components gradually melt, and the ordered crystal structure is transformed into an amorphous glass structure. Because of the high melting temperature and narrow temperature range of the melt reaction, during the melting process, the melting temperature or the melting time must be increased to homogenize the basalt melt.

      PubDate: 2017-03-03T15:23:25Z
  • Bending characteristics of hardwood lamellae in the elastic region
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Milan Gaff, Marián Babiak, Vojtěch Vokatý, Miroslav Gašparík, Daniel Ruman
      This article focuses on the analysis of the effect of certain factors (wood species, degree of densification, material thickness and number of loading cycles) on the modulus of elasticity (MOE), limit of proportionality (LOP) and elastic potential (PE) of beech and aspen wood lamellae measured in the elastic region of the stress-strain curve under bending loading. Beech wood achieved higher MOE, LOP and PE values than aspen wood. As the degree of densification increased, the MOE and LOP also increased, while the PE remains almost unchanged. MOE values increase as the material thickness increases, while the LOP and PE decrease. Cyclic loading caused an increase in the LOP and PE, but it had little effect on the MOE. Cyclic loading had a greater effect on densified wood than non-densified wood.

      PubDate: 2017-03-03T15:23:25Z
  • Theoretical investigation on impact resistance and energy absorption of
           foams with nonlinearly varying density
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Hu Liu, Zhiqiang Zhang, Hua Liu, Jialing Yang, Hong Lin
      Compared with traditional uniform foams, the density-graded foam exhibits more excellent impact resistance and energy absorption capacity. In order to exploit its full potential for improved dynamic performance, the density profile should be designed properly. However, the effect of the nonlinear density gradient profile on the impact resistance and energy absorption characteristics is still unclear. The aim of this paper is to study the dynamic response of a nonlinear density-graded foam rod impinged by a mass projectile. The density in the foam rod varies along the longitudinal direction in a power-law exponent form and the coupling effect of density gradient on material properties of foam rods is taken into account. Both the negative and positive density gradients are investigated. The dynamic stress at the impinging and support ends and the energy absorption capacity for different power-law exponents are compared. The present nonlinear gradient model can be degenerated into the previous linear gradient model when the exponent is equal to 1. To validate the theoretical analysis, the finite element simulation is also carried out and a good agreement is achieved. The results indicate that the impact resistance and energy absorption capacity of the foam rod can be improved by using proper nonlinear density-graded profiles.

      PubDate: 2017-03-03T15:23:25Z
  • Modeling framework for free edge effects in laminates under
           thermo-mechanical loading
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): M.S. Islam, P. Prabhakar
      In this paper, a novel Quasi-2D (Q-2D) plane strain formulation for predicting interlaminar stresses in multi-directional laminates is developed and implemented within the finite element method framework. In particular, analyses of free edge stresses in composite laminates subjected to uniform axial and/or thermal loading are conducted. The Q-2D modeling approach presented here is validated by comparing the predicted interlaminar stresses with corresponding 3D models and previously published data. Computational time required for determining the interlaminar stresses using Q-2D model is approximately 30 times lower than the 3D analysis of the same laminate. Also, the Q-2D model is implemented within a commercially available software by modifying a 3D model to behave like a 2D model. This is particularly advantageous over developing an in-house finite element method code to capture the complex free edge stress states in multi-directional composites. Hence, the current framework can potentially be used as a computational tool for efficiently predicting the interlaminar stresses in different laminates subjected to thermo-mechanical loading, which can assist in determining interlaminar regions susceptible to free edge delamination.

      PubDate: 2017-03-03T15:23:25Z
  • Salt-fog spray aging of jute-basalt reinforced hybrid structures: Flexural
           and low velocity impact response
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): V. Fiore, T. Scalici, F. Sarasini, J. Tirilló, L. Calabrese
      In this work, a study on the aging resistance of jute and jute-basalt interply hybrid laminates exposed to salt-fog is presented with the aim to investigate the possibility to enhance the durability of natural fiber reinforced composites for marine application by a ply-substitution approach. In particular, jute and basalt/jute reinforced composite plates were manufactured by vacuum assisted resin infusion in two different staking sequences (i.e., intercalated and sandwich-like basalt-jute) and aged under salt fog conditions. The effects of the accelerated aging at increasing times on the mechanical response of laminates were assessed in both quasi static (three point bending) and dynamic (low velocity impact) conditions. Overall, it was found that the substitution of external jute layers with basalt layers (i.e. sandwich like configuration) represents the best solution to enhance the durability of structures exposed to salt fog aging conditions. This is highlighted by lower decrements, after 90 days of aging, of the quasi-static flexural modulus and the impact peak load (16% and 3.5%, respectively) compared to those showed by jute laminate (40% and 10.5%, respectively).

      PubDate: 2017-03-03T15:23:25Z
  • Mechanical characterization of the elastoplastic response of asphalt felt
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Claudio A. Bustos, Claudio M. García–Herrera, Diego J. Celentano, Diego A. Vasco
      A numerical and experimental analysis of the mechanical response of asphalt felt paper is presented. This material is widely used as a moisture barrier in buildings made of light materials. To ensure such function, it is necessary for this material not to be torn during its installation and operation and, for this reason, it is important to know its mechanical behavior in detail. To that end, tensile and bulge tests were carried out and respectively used to characterize the in-plane and out-of-plane rate-independent elastoplastic material responses which were observed to be strongly dependent on the directions of the cellulose fibers. The constitutive model considers the anisotropic character of the material assuming the Hill-48 function to define both the yield surface and the non-associated plastic flow rule to properly predict the mechanical behavior for the full deformation ranges of both tests. The procedure to fit the material parameters is carried out via a proposed iterative numerical-experimental methodology. The obtained results are found to adequately describe the material response in both the tensile and bulge tests.

      PubDate: 2017-03-03T15:23:25Z
  • The nonlinear vibration of orthotropic functionally graded cylindrical
           shells surrounded by an elastic foundation within first order shear
           deformation theory
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): A.H. Sofiyev, D. Hui, V.C. Haciyev, H. Erdem, G.Q. Yuan, E. Schnack, V. Guldal
      The non-linear free vibration behavior of functionally graded (FG) orthotropic cylindrical shell interacting with the two-parameter elastic foundation is investigated. The major goal of this research was to obtain a solution for the non-linear frequencies associated with the problem outlined above. The dynamic stability and compatibility equations of FG orthotropic cylindrical shells surrounded by an elastic foundation are derived within the first order shear deformation theory (FSDT) and von Kármán strain displacement relationships, and then superposition and Galerkin methods are adopted to convert the above equations into a nonlinear ordinary differential equation. The expression for non-linear frequency of FG orthotropic cylindrical shell surrounded by an elastic foundation within the FSDT is obtained using the homotopy perturbation method (HPM). In particular, similar expression in the framework of the classical shell theory (CST) is obtained, also. The results are compared and validated with the results available in the literature. Finally, the calculation and presentation of the effect of many parameters included in the analysis conclude the goals to be reached in the study.

      PubDate: 2017-03-03T15:23:25Z
  • Global sensitivity analysis of load distribution and displacement in
           multi-bolt composite joints
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Hong-Shuang Li, Ru-Jia Gu, Xiang Zhao
      This paper presents the development of a novel methodology for global sensitivity analysis of multi-bolt composite joints. Two sources of uncertainty were considered, i.e., the mechanical properties of composite plies and the bolt-hole clearance which comes from assembly phase. The uncertainty propagation in the composite plate was derived through the classical laminate theory, while the load distribution within bolts and the joint displacement were determined by an analytical spring-based method. A kind of Monte Carlo simulation was used to calculate the variance-based sensitivity indices. Furthermore, the proposed methodology was applied to a generic single-lap composite joint, which can also be extended to represent double-lap joints, to identify the significant input random variables with respect to structural responses of the joint. Useful conclusions for the design of multi-bolt composite joints were obtained from the computational results and discussions.

      PubDate: 2017-03-03T15:23:25Z
  • Analytical solutions for yield onset achievement in FGM thick walled
           cylindrical tubes undergoing thermomechanical loads
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): S. Ansari Sadrabadi, G.H. Rahimi, R. Citarella, J. Shahbazi Karami, R. Sepe, R. Esposito
      A thick-walled cylindrical tube made of a Functionally Graded Material (FGM) and undergoing thermomechanical loads has been investigated. The tube material properties have been considered to be isotropic and vary as a power function of the radius. A yield variable parameter has been defined according to von Mises criterion, has been introduced into the stress governing equation. The value of the radius where yielding may appear has been assessed in relation to internal pressure, temperature difference and heat generation. An analytical solution has been derived, allowing the prediction of radial position of yeld onset as related to the elastic limit domain configuration according to FGM parameter settings and thermomechanical loads. Moreover, elastic limit region changes have been investigated for two different designs of FGM materials. Stress and yield parameter variations along the thickness have been obtained. The effects of FGM parameters and of the shape factor of the cylinder cross-section on initial yielding due to thermomechanical loads have been studied.

      PubDate: 2017-03-03T15:23:25Z
  • Three-dimensional free vibration analysis of levy-type laminated plates
           using multi-term extended Kantorovich method
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Poonam Kumari, Susanta Behera
      A closed form three-dimensional (3D) free vibration solution for a rectangular laminated plate with Levy-type support conditions is presented first time using recently developed extended Kantorovich method. Hamiltons principle is extended to develop a mixed formulation in terms of displacements and stresses as primary variables. The present solution will serve as a benchmark for assessing two-dimensional (2D) theories and 3D numerical solutions. Natural frequencies are tabulated for composite and sandwich laminates (first time) for different boundary conditions. It is found that single term solution is sufficient enough for obtaining accurate natural frequencies. But stresses near the clamped edge are accurately predicted by multi-term solution (n = 2). The effect of the span to thickness ratio and in-plane modulus ratios on the natural frequency is also studied.

      PubDate: 2017-03-03T15:23:25Z
  • Pull-out and shear-strength models for FRP spike anchors
    • Abstract: Publication date: 1 May 2017
      Source:Composites Part B: Engineering, Volume 116
      Author(s): Paula Villanueva Llauradó, Tim Ibell, Jaime Fernández Gómez, Francisco J. González Ramos
      Spike anchors are a promising way to enhance the maximum capacity and post-peak load-strain response of externally-bonded fibre-reinforced polymer (FRP) materials for retrofitting of concrete structures. Although laboratory testing has proven the effectiveness of these spike anchors (also known as fan anchors), little work has been conducted to provide an analytical basis on which to rely on such anchorage systems. For instance, which parameters govern the behaviour of these anchors? Without an analytical or predictive basis for the behaviour of such anchors, their use will be limited. Therefore, this paper presents an analytical model to be able to predict the behaviour of such anchors, by including important geometrical and installation parameters. This model will, for the first time, allow engineers to specify, with confidence, the use of spike anchors as a method to anchor FRP sheets and plates to structural concrete members.

      PubDate: 2017-03-03T15:23:25Z
  • Mechanical characterization of carbon nanotubes based polymer composites
           using indentation tests
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): A. El Moumen, M. Tarfaoui, K. Lafdi
      In this paper, instrumented indentation testing was used to determine the elastic mechanical properties of multiwall carbon nanotubes (CNTs) reinforced polymer composites. A finite element analysis model for simulating micro-indentation test was developed using ABAQUS software and confronted to experimental tests. It seems that CNTs reinforced polymer composites shows an improved of mechanical properties. The microstructure of indentation mark has been evaluated using scanning electronic microscopes and compared with the microstructure of numerical models. It results that adding small amount of CNTs improves the fracture interfacial rigidity and can stop micro-cracks evolution.

      PubDate: 2017-02-23T15:16:32Z
  • Internal friction behaviour of carbon fibre reinforced multilayered
           (PyC–SiC)n matrix composites
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): Yan Jia, Kezhi Li, Lizhen Xue, Junjie Ren, Shouyang Zhang
      Carbon fibre reinforced multilayered (PyC–SiC)n matrix (C/(PyC–SiC)n) composites were prepared by alternate deposition of pyrocarbon (PyC) and SiC inside preforms via chemical vapour infiltration. The matrix microstructures and internal friction behaviours of C/(PyC–SiC)n composites (n = 1, 2 and 4) under different testing conditions of frequency, strain amplitude and temperature were studied. The results show that with increasing the number of sequences (n), the internal friction increases due to the enhancement of interfacial internal friction. The internal friction of C/(PyC–SiC)n composites increases with the increase of frequency related to thermoelastic mechanism, but exhibits anomalous amplitude effect in the testing amplitude range. Effect of temperature on internal friction behaviours is attributed to combined effects of carbon fibres, PyC–SiC matrices and interfaces between fibres and PyC, adjoining PyC and SiC layers. It is also found that internal friction is sensitive to microstructural defects induced by damage. These results indicate that internal friction is an effective and efficient method to characterize the structural evolution and internal damage of C/(PyC–SiC)n composites non-destructively.

      PubDate: 2017-02-23T15:16:32Z
  • Hemp fiber reinforced polypropylene composites: The effects of material
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): Theresa Sullins, Selvum Pillay, Alastair Komus, Haibin Ning
      Natural fiber reinforced thermoplastic matrix composites have been increasingly used in semi-structural applications in automotive applications because of their good specific strength and modulus, low carbon footprint and recyclability. This research work studies the effects of material treatment(s) on the mechanical behaviors of hemp fiber reinforced polypropylene (PP) composites. The material treatment(s) are realized by chemically treating the hemp fiber with different concentration NaOH and/or adding maleic anhydride grafted polypropylene (MAPP) to the PP matrix. The purpose of the material treatment(s) is to enhance the bonding between the hemp fibers and the polypropylene matrix which otherwise has low surface energy and limited bonding. The mechanical behaviors are investigated with different combinations of material treatment(s) such as 5 wt% MAPP, 5% NaOH treated hemp fiber, 10% NaOH treated hemp fiber, and 5% NaOH + 5 wt% MAPP. 15 wt% and 30 wt% hemp fiber loadings are used in the composites with these material treatments. It is found that the material treatment(s) result(s) in composites with better mechanical properties compared to the composites without any treatment(s). The composites with 5 wt% MAPP addition show the best mechanical properties.

      PubDate: 2017-02-23T15:16:32Z
  • Snap-through behaviour of a bistable structure based on viscoelastically
           generated prestress
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): Bing Wang, Chao Ge, Kevin S. Fancey
      A novel form of shape-changing bistable structure has been successfully developed through the use of viscoelastically generated prestress. Bistability is achieved through pairs of deflecting viscoelastically prestressed polymeric matrix composite (VPPMC) strips, which are orientated to give opposing cylindrical configurations within a thin, flexible resin-impregnated fibreglass sheet. This arrangement enables the structure to ‘snap through’ between one of two states by external stimulation. Deflection from the VPPMC strips occurs through compressive stresses generated from the non-uniform spatial distribution of nylon 6,6 fibres undergoing viscoelastic recovery. In this study, snap-through behaviour of the bistable structure is investigated both experimentally and through finite element (FE) analysis. By using experimental results to calibrate FE parameter values, the modelling has facilitated investigation into the development of bistability and the influence of modulus ratio (fibreglass sheet: VPPMC strip) on the snap-through characteristics. Experimental results and FE simulation show good agreement with regard to snap-through behaviour of the bistable structure and from this, the bistability mechanisms are discussed.

      PubDate: 2017-02-23T15:16:32Z
  • Buckling analysis of Silicon carbide nanotubes (SiCNTs) with surface
           effect and nonlocal elasticity using the method of HDQ
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): Kadir Mercan, Ömer Civalek
      As the parallel to the advancement of technology in nano-sizes, the importance of nanotubes is rising every day. The mostly worked and used nanotubes are Carbon Nanotubes (CNT) due to their superior mechanical and electrical properties. On the other hand, the technology always needs better materials with superior mechanical, electrical conductivity and thermal properties. After a couple years of working with Carbon nanotubes, scientists have discovered different types of nanotube such boron nitride and Silicon carbide nanotubes (SiCNTs). In this work, the stability of the Silicon carbide nanotube is investigated in the static buckling case with surface effect. Nonlocal continuum theory is also used in order to see the difference between two higher-order elasticity theories. The stability of nanotubes has an important role since it is used in high-tech equipment. Buckling behavior of SiCNTs is discussed by using the continuum model based on the Euler-Bernoulli beam theory for different boundary conditions in conjunctions with the surface effect and nonlocal elasticity theory. The harmonic differential quadrature method (HDQ) is used for numerical simulations. Some parametric values for critical buckling loads have been obtained with different geometrical quantities of SiCNTs. The size effects on results have been also investigated by the surface elasticity and Eringen's nonlocal elasticity parameters.

      PubDate: 2017-02-23T15:16:32Z
  • An optimal reduction technique for rGO/ABS composites having high-end
           dynamic properties based on Cole-Cole plot, degree of entanglement and
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): Vinay Panwar, Kaushik Pal
      This work enlightens the effect of three different derivatives of graphene on mechanical, thermal and rheological properties of acrylonitrile-butadiene-styrene (ABS) composites prepared via melt-mixing technique. These nanofillers i.e. graphene oxide (GO), chemically reduced graphene oxide (rGO-C) and thermally reduced graphene oxide (rGO-Th), with selective low percolation threshold in ABS, brought erratic outcome. It has been noticed that rGO-C acts as better reinforcement in ABS than other derivatives. Improvement in tensile strength by 1.8-fold, storage modulus by 12% and glass transition by 11 °C has been achieved with rGO-C/ABS composites. Some typical secondary correlations based on dynamic storage modulus i.e. variations in stiffness, degree of entanglement and C-factor, have been used to exaggerate the change in dynamic properties more precisely. Creep and recovery behaviour, investigated at different environment temperatures and three different stress levels, also shown minimum creep deformation and superior recovery using rGO-C.
      Graphical abstract image

      PubDate: 2017-02-23T15:16:32Z
  • Enhanced dielectric properties of immiscible poly (vinylidene
           fluoride)/low density polyethylene blends by inducing multilayered and
           orientated structures
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): Xiang Lin, Lili Fan, Dongyun Ren, Zhiwei Jiao, Phil Coates, Weimin Yang
      In order to improve the frequency-dependent dielectric properties of the immiscible polymeric blends which were melt-compounded by composing poly (vinylidene fluoride) (PVDF) and low density polyethylene (LDPE), the layer multiplication and the solid phase orientation technologies were respectively adopted as two effective strategies to optimize the dispersion state and the orientation of internal microstructure, aiming at reducing physical porosity and improving the barrier performance as well as crystal phase of the polymer extrudates. Results comparison showed the dielectric properties were greatly dependent on the crystal type and the physical porosity density which were also emphasized as the interfacial effect in the previous work [ref. 29: Lin X et al., J Appl Polym Sci 2015; 132(36), 42507]. It was found that the multilayer-structure manipulation could substantially improve the dispersion state between the two immiscible components, enhance the mechanical performance and reduce the internal defects and increase the dielectric constant while keeping the dielectric loss stable. By uniaxial stretching the sample sheets at a rubber state temperature of ca. 10–20 °C below the melting point, crystal transformation was induced by increasing molecular chains orientation degree which was also contributed to the enhancement of the dielectric properties. These techniques implied the potential as a promising way for inducing functional structures of polymeric blends.

      PubDate: 2017-02-23T15:16:32Z
  • Nonlinear vibration of single-walled carbon nanotubes with nonlinear
           damping and random material properties under magnetic field
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): T.-P. Chang
      This paper copes with the statistical dynamic behaviors of nonlinear vibration of the single-walled carbon nanotubes (SWCNTs) under longitudinal magnetic field by considering the effects of the geometric nonlinearity and nonlinear damping. Both the Young's modulus of elasticity and mass density of the SWCNTs are considered as stochastic with respect to the position to actually characterize the random material properties of the SWCNTs. Based on the theory of nonlocal elasticity, the small scale effects of the nonlinear vibration of the SWCNTs are investigated. By using the Hamilton's principle, the nonlinear governing equations of the single-walled carbon nanotubes subjected to longitudinal magnetic field are derived. The Monte Carlo Simulation, Galerkin's method and the multiple scale method are adopted to solve the nonlinear governing equation and to calculate the statistical response of the SWCNTs. Some statistical dynamic responses of the SWCNTs such as the mean values and standard deviations of the midpoint deflections are computed, the effects of the small scale coefficients, magnetic field, nonlinear damping and the elastic stiffness of matrix on the statistical dynamic responses of the SWCNTs are investigated and discussed.

      PubDate: 2017-02-23T15:16:32Z
  • Homogenization of hexagonal and re-entrant hexagonal structures and wave
           propagation of the sandwich plates with symplectic analysis
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): Kai Zhang, Zi-Chen Deng, Xiao-Jian Xu, Jun-Miao Meng, Xian-Hong Jiang
      The aim of this work is to provide closed-form expressions of the effective elastic constants of hexagonal and re-entrant hexagonal structures, which contain the variable dimensional parameters, such as the relative density, aspect ratio, length ratio and the cell wall angle. We also numerically investigate the dynamic properties of the sandwich plates with hexagonal cores. By taking into account the bending, axial and shearing deformations of the unit cell walls, the effective elastic constants are derived. In order to analyze the wave propagation of the sandwich plates, the original governing equations are converted into a set of the first-order governing differential equations in the Hamilton system, by introducing the dual variables and with the help of a variational principle. The precise integration method in conjunction with the extended Wittrick-Williams algorithm is utilized to numerically solve these equations to obtain the frequencies of structures. The effects of relative density, length ratio, cell wall angle and material distribution parameter on the dispersion relations of hexagonal and re-entrant hexagonal structures are investigated. It is found that the stiffness plays a more dominant role on the dispersion relations than that of the mass, and the effects of length ratio and material distribution parameter are more prominent than that of the cell wall angle.

      PubDate: 2017-02-23T15:16:32Z
  • Space charge and dielectric behavior of epoxy composite with SiO2-Al2O3
           nano-micro fillers at varied temperatures
    • Abstract: Publication date: 1 April 2017
      Source:Composites Part B: Engineering, Volume 114
      Author(s): Tian Fuqiang, Zhang Lin, Zhang Junliang, Peng Xiao
      Dielectric properties at high temperatures are important for epoxy resin used as insulation and package materials operating at varied temperatures in electrical apparatuses and electronic devices. We investigated the dielectric properties of epoxy resin and its composite with SiO2-Al2O3 nano-micro fillers at varied temperatures by combined study of space charge distribution, complex dielectric permittivity and conduction current between 20 and 200 °C. The results show that space charge behavior in epoxy resin and its composite is dominated by electronic charge transport below the glass transition temperature T g and by ion transport above T g. The real and imaginary parts of complex permittivity increase to extremely high values at temperatures above T g. The conduction current increases with a rise in temperature and shows an obvious transition from electronic charge transport below T g to ionic charge transport above T g. The composite shows weaker space charge accumulation, lower complex permittivity and conduction current than EP above T g. Combined analysis of the results indicate that ion accumulation and transport dominate the dielectric properties of epoxy resin and its composite at high temperatures above T g. The nano-micro fillers in the composite can significantly suppress the ions transport and accumulation.

      PubDate: 2017-02-23T15:16:32Z
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Heriot-Watt University
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