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  Subjects -> ENGINEERING (Total: 2267 journals)
    - CHEMICAL ENGINEERING (190 journals)
    - CIVIL ENGINEERING (183 journals)
    - ELECTRICAL ENGINEERING (99 journals)
    - ENGINEERING (1196 journals)
    - ENGINEERING MECHANICS AND MATERIALS (391 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (64 journals)
    - MECHANICAL ENGINEERING (89 journals)

ENGINEERING (1196 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: 216)
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: 5)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 6)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 3)
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: 18)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
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: 13)
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  
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: 7)
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)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 8)
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: 4)
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: 4)
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: 4)
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: 5)
Composite Structures     Hybrid Journal   (Followers: 252)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 176)
Composites Part B : Engineering     Hybrid Journal   (Followers: 224)
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: 7)
Control Engineering Practice     Hybrid Journal   (Followers: 40)
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  
Current Applied Physics     Full-text available via subscription   (Followers: 4)

        1 2 3 4 5 6 | Last

Journal Cover Composites Part B : Engineering
  [SJR: 2.125]   [H-I: 75]   [224 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1359-8368
   Published by Elsevier Homepage  [3032 journals]
  • 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
       
  • A wave-based computational method for free vibration, wave power
           transmission and reflection in multi-cracked nanobeams
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Arian Bahrami
      In this paper, the wave propagation method and the nonlocal elasticity theory are utilized to analyze the vibration, wave power transmission and reflection in multi-cracked Euler-Bernoulli nanobeams. This aim is pursued by deriving the propagation, reflection and transmission matrices and comparing the natural frequencies obtained by these matrices with the available results in the literature. Then, the nonlocal and crack-severity effects on the natural frequencies are presented for some combinations of the boundary conditions. Finally, the effects of nonlocal and crack-severity parameters on the reflected and transmitted power of a wave incident upon a crack location are studied in details for cracked nanobeams. The results obtained via the reflection and transmission matrices will provide valuable insights into the subject of wave power reflection and transmission analysis in nanoscale structures for the future. The computer coding of the proposed method is much easier than the classical vibration analysis methods for similar analyses which makes it more appropriate in implementation.

      PubDate: 2017-04-18T08:20:13Z
       
  • Exact three-dimensional static analysis of single- and multi-layered
           plates and shells
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Salvatore Brischetto
      This new work proposes an exact three-dimensional static analysis of plates and shells. One-layered and multilayered isotropic, orthotropic, sandwich and composite structures are investigated in terms of displacements and in-plane and out-of-plane stresses through the thickness direction. Proposed structures are completely simply-supported and a transverse normal load is applied. The proposed method is based on the 3D equilibrium equations written using general orthogonal curvilinear coordinates which are valid for spherical shells. Cylindrical shell, cylinder and plate results are obtained as particular cases of 3D spherical shell equations. All the considered structures are analyzed without any geometrical approximation. The exact solution is possible because of simply-supported boundary conditions and harmonic form for applied loads. The shell solution is based on a layer-wise approach and the second order differential equations are solved using the redouble of variables and the exponential matrix method. A preliminary validation of the model is made using reference results in the literature. Thereafter, the proposed exact 3D shell solution is employed with confidence to provide results for one-layered and multilayered plates, cylinders, cylindrical shell panels and spherical shell panels. All these geometries are analyzed via a unified and general solution, and the obtained results can be used to validate future numerical methods proposed for plates and shells (e.g., the finite element method or the differential quadrature method). Proposed results allow to remark substantial features about the thickness of the structures, their geometry, the zigzag effects of displacements, the interlaminar continuity of displacements and transverse stresses, and boundary loading conditions for stresses.

      PubDate: 2017-04-18T08:20:13Z
       
  • The effects of intertube bridging through graphene nanoribbons on the
           mechanical properties of pillared graphene
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Deniz Bilgili, Levent Kirkayak, Mesut Kirca
      In this study, effects of intertube bridging and bridging type on the mechanical properties of pillared graphene are investigated through molecular dynamics (MD) simulations. For this purpose, atomistic models of pillared graphene structures consisting of six carbon nanotubes (CNTs), which are arranged in a regular hexagonal pattern, are built by employing graphene nanoribbons as intertube bridging units. In the first phase, tensile behaviors of two pillared graphene structures (i.e. with and without intertube bridging) are compared to understand the effects of intertube bridging. In the second phase, two different models for the interconnected pillared graphene are prepared by using graphene nanoribbons with different lengths. Numerical tensile tests with the same settings are conducted on the specimens of the proposed nanostructures, and their mechanical properties including tensile strength and toughness are examined. Based on the results, it is shown that intertube bridging between CNT units significantly increases the tensile strength of pillared graphene. Furthermore, it is also demonstrated that, depending on the length of the interconnecting graphene nanoribbons, intertube bridging can either increase or decrease the toughness of pillared graphene nanostructures, thereby providing tunable hybrid mechanical characteristics.

      PubDate: 2017-04-11T10:43:00Z
       
  • Experimental investigation on damage evolution in cross-ply laminates
           subjected to quasi-static and fatigue loading
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Haojie Shen, Weixing Yao, Wenxuan Qi, Junda Zong
      In this paper an experimental investigation on damage evolution in cross-ply glass fiber reinforced plastic (GFRP) laminates under quasi-static and fatigue loading is presented. Four configurations of lay-up ([02/904]s, [02/902]s, [0/904]s and [0/903/0/903]s) with different thicknesses of cracking plies were selected to study the in-situ behavior in the damage initiation, evolution and saturation. Combined with the imaging features of different damages and the characteristic of damage evolution in the laminates, light transmission method was employed to observe the damage state and to record matrix crack density. In fatigue tests, eight stress levels were chosen for each configuration of laminates, including four lower stress levels below the stress level corresponding to the first transverse crack initiation. A conclusion was drawn from the comparison of the results that the fatigue loading with lower stress level accelerates the process of damage evolution and generates damages more thoroughly at failure.

      PubDate: 2017-04-11T10:43:00Z
       
  • Prediction of modulus at various strain rates from dynamic mechanical
           analysis data for polymer matrix composites
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Steven Eric Zeltmann, Keerthana A. Prakash, Mrityunjay Doddamani, Nikhil Gupta
      Understanding and modeling the behavior of polymers and composites at a wide range of quasi-static and high strain rates is of great interest to applications that are subjected to dynamic loading conditions. The Standard Linear Solid model or Prony series frameworks for modeling of strain rate dependent behavior are limited due to simplicity of the models to accurately represent a viscoelastic material with multiple relaxations. This work is aimed at developing a technique for manipulating the data derived from dynamic mechanical analysis to obtain an accurate estimate of the relaxation modulus of a material over a large range of strain rate. The technique relies on using the time-temperature superposition principle to obtain a frequency-domain master curve, and integral transform of this material response to the time domain using the theory of viscoelasticity. The relaxation function obtained from this technique is validated for two polymer matrix composites by comparing its predictions of the response to uniaxial strain at a prescribed strain rate to measurements taken from a separate set of tension experiments and excellent matching is observed.

      PubDate: 2017-04-11T10:43:00Z
       
  • Flexible solid electrolyte based on UV cured polyurethane
           acrylate/succinonitrile-lithium salt composite compatibilized by
           tetrahydrofuran
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Pengfei Lv, Jian Yang, Guobiao Liu, Hao Liu, Shaomin Li, Changyu Tang, Jun Mei, Yuntao Li, David Hui
      The safety issues of lithium batteries caused by liquid organic electrolyte have been driving people to seek safer solid-like electrolytes. Herein, we report effort to employ Polyurethane acrylate (PUA) elastomer and Succinonitrile (SN)-based plastic crystal electrolyte (PCE) to fabricate a composite PCE (CPCE) by solution blending followed by rapid UV curing. During fabrication process, the phase separation between PUA and SN-based PCE can be suppressed by adding Tetrahydrofuran (THF). Consequently, the improved compatibility results in an improved mechanical strength in the CPCE and makes PUA impart the good stretching and resilient properties to the CPCE. The optimized CPCE presents a maximum stretching strain of 90.6% and can bear cyclic stretching-releasing test. Besides, the CPCE exhibits a high ionic conductivity of 0.91 × 10−3 S cm−1 at 30 °C and a wide electrochemical stability window of 4.8 V. Thus, this stretchable CPCE could be used in flexible batteries for emerging applications such as wearable electronic devices and flexible sensors.
      Graphical abstract image

      PubDate: 2017-04-11T10:43:00Z
       
  • Erosion-wear, mechanical and thermal properties of silica filled epoxy
           nanocomposites
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): J. Abenojar, J. Tutor, Y. Ballesteros, J.C. del Real, M.A. Martínez
      Different nano- and micro-fillers are added to modify the mechanical properties, wear resistance, thermal properties and the curing process of polymers. A very important application for epoxy resins is to be used as coating for anti-cavitation painting. Pyrogenic silica is already used in adhesives and paints, being its application related to rheology. The objective of this work is to study the effect of pyrogenic silica on epoxy resins, usually not present in their formulation. SiO2/epoxy nanocomposites with two different loads of nano-silica, 3 and 5 wt% were manufactured. In particular, the study focuses on the influence that the addition of nano-silica has on the mechanical, wear and cavitation erosion properties as well as on the thermal properties and the curing reaction. To accomplish these goals, nanocomposite samples in bulk and as coating were prepared. Mechanical properties (hardness, bending and tensile strength), wear resistance (in bulk and coating) and cavitation erosion were evaluated. The epoxy curing process and the influence of nano-SiO2 additions on the glass transition temperature (T g ) were studied by Differential Scanning Calorimetry (DSC). In general, a plasticising effect was observed with nano-silica addition. Moreover, the resistance to erosion by cavitation, in terms of cumulative erosion and erosion rate, was higher for the nanocomposites than for clear resin.

      PubDate: 2017-04-11T10:43:00Z
       
  • Deformation-induced blueshift in emission spectrum of CdTe quantum dot
           composites
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Pan Xiao, Fujiu Ke, Yilong Bai, Min Zhou
      Polymer or glass films impregnated with quantum dots (QDs) have potential applications for mesoscale stress/strain sensing in the interior of materials under mechanical loading. One requirement in the development of such nanocomposite sensor materials is the establishment of calibrated relations between shifts in the emission spectrum of QD systems and the input stress/strain on the composites. Here, we use a multiscale computational framework to quantify the strain-dependent blueshift in the emission spectrum of CdTe QDs uniformly distributed in a matrix material under loading of a range of strain triaxiality. The framework, which combines the finite element method, molecular dynamics simulations and the empirical tight-binding method, captures the QD/matrix interactions, possible deformation-induced phase transformations and strain-dependent band structures of the QDs. Calculations reveal that the response of the QDs is strongly dependent on state of input strain. Under hydrostatic compression, the blueshift increases monotonically with strain. Under compression with lateral/axial strain ratios between 0.0 and 0.5, the blueshift initially increases, reaches a peak at an intermediate strain, and subsequently decreases with strain. This trend reflects a competition between increases in the energy levels associated with the conduction and valence bands of the QDs. The deformation-induced blueshift is also found to be dependent on QD orientations. The averaged blueshift over all orientations for the composite under uniaxial strain condition explains the blueshift variation trend observed in laser-driven shock compression experiments. Based on the simulation result, guidelines for developing QD composites as stress/strain sensing materials are discussed.

      PubDate: 2017-04-11T10:43:00Z
       
  • Three-dimensional modelling of laminated glass bending on two-dimensional
           in-plane mesh
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): J. Jaśkowiec, P. Pluciński, A. Stankiewicz, Cz. Cichoń
      The article presents an analysis of bending of a laminated glass (LG) plate. The analysis uses a 3D physical model in which only a 2D in-plane mesh is applied for numerical analysis. The LG consists of glass panes bonded by films of polymers, so the LG is layered structure. The approach in which the 3D spatial approximation in each layer is a combination of a 2D in-plane approximation with a 1D transverse approximation (along the plate thickness) is used. In consequence, the final numerical model is based on a 2D in-plane finite element mesh. A special postprocessing procedure, devised specially to be used in this method, has been developed which enables visualization of a full 3D deformation as well as all six stress components. The method is relatively simple, robust and effective, and it gives correct 3D results. The accuracy of the method has been tested with the use of some known solutions as well as by comparison with analytical solution, well established FEM procedures and with experimental results. In the examples the two-, three- and four-paned laminated glass is analysed. In spite of the fact that the numerical model is 2D, the full 3D results are obtained. For the sake of clarity, this paper is limited to elastic plate bending, but the method can be directly applied for LG subjected to thermal or thermo-mechanical load.

      PubDate: 2017-04-11T10:43:00Z
       
  • Enhancement of tribological properties of polymer composites reinforced by
           functionalized graphene
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Yunlong Li, Shijie Wang, Quan Wang
      Polymer composites reinforced by pristine and functionalized graphene are investigated to identify the improvement of tribological properties of polymer composites. A pull-out process is conducted to study the interfacial interactions between polymer matrices and graphene reinforcements using molecular dynamics simulations. Molecular layer models containing Fe atoms as the top nano-layer are built to study the enhancement of tribological properties of the polymer composites by sliding the top Fe nano-layer on the surface of the polymer matrix. The simulation results show that decreases of about 13% and 42.3% in the average friction coefficient and abrasion rate of the functionalized graphene/polymer composites can be achieved. In order to provide the understandings of the findings, the interfacial interaction energy, RDF values between graphene and polymer matrix are particularly calculated and discussed.

      PubDate: 2017-04-11T10:43:00Z
       
  • Quantitative determining interface information of nano composite by
           synchrotron radiation small-angle X-ray scattering
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Xu Xia, Jinghua Yin, Bo Su, David Hui, Rentong Yu, Xiaoxu Liu
      The interface plays a decisive role on the performance of nano dielectric composite films, and researchers have made tremendous efforts to confirm the existence of the interface in nano dielectric composite films. However, establishing quantitative determining interface information of nano composites is very difficult. In this paper, a typical nano dielectric, PI/SiO2 composite film with content of 10% SiO2 was prepared by an in-situ method and the microstructures of PI/SiO2 and pure PI were obtained by the small-angle X-ray scattering (SAXS), which is a non-destructive testing method. The TEM results show that the average grain diameter of SiO2 particles and the thicknesses of the interfaces are about 7.5 nm and 2.2 nm, respectively. The SAXS results are confirmed by direct TEM imaging method, in which SiO2 particles adsorb the surrounding PI molecular chains, and form the interfaces. The average grain diameters of SiO2 (not including the absorbed PI) particles and the thicknesses of interfaces are about 6.8 nm and 2.6 nm respectively. From this paper, we have proved that SAXS is a new effective means for the quantitative determining of interface information of nano composites.
      Graphical abstract image

      PubDate: 2017-04-11T10:43:00Z
       
  • Magnetoelectric response on Terfenol-D/ P(VDF-TrFE) two-phase composites
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): R. Brito-Pereira, C. Ribeiro, S. Lanceros-Mendez, P. Martins
      Magnetoelectric (ME) particulate composites films composed of Terfenol-D (TD) particles embedded in P(VDF-TrFE) (70/30) polymer have been developed. The effect of TD content on the mechanical, dielectric, electric, magnetic, piezoelectric and ME properties was studied and discussed. It is shown that the addition of TD particles into the polymer matrix increased the Young's modulus of from 0.86 GPa from the pristine co-polymer to 0.96 GPa for the composite with 60 wt.% filler content. The dielectric characterization showed an increase of the permittivity and dielectric loss with increasing filler content, being maximized for sample with 60 wt.% of TD (13 and 0.05 respectively). The poling process optimized the d33 piezoelectric response of the composites to ≈ -15 pC.N−1 value. The room temperature ferromagnetism (150 Oe coercivity and 8.6 emu.g−1 saturation magnetization) and high magnetoelectric voltage coupling (38 mV cm−1.Oe−1), the highest reported for two phase TD polymer composites, allows the development of flexible ME devices.
      Graphical abstract image

      PubDate: 2017-04-11T10:43:00Z
       
  • Fatigue and reliability analysis of nano-modified scarf adhesive joints in
           carbon fiber composites
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): U.A. Khashaba, A.A. Aljinaidi, M.A. Hamed
      Enhancing the fatigue performance of scarf adhesive joints (SAJs) in carbon fiber-reinforced epoxy (CFRE) composite structures via incorporation of nanofillers into the epoxy adhesive has not yet been fully investigated and is the subject of this study. The optimum weight percentages of multi-walled carbon nanotubes (MWCNTs), SiC and Al2O3 nanofillers were ultrasonically dispersed in Epocast 50-A1/946 epoxy. The nanophased matrices were used to fabricate the SAJs with 5° scarf angle. Fatigue tests were conducted at constant-load amplitude, frequency of 10 Hz and stress ratio of 0.1. Result from fatigue tests showed that the gain/loss in the fatigue lives of the modified SAJs with MWCNTs, SiC and Al2O3 are respectively 19%, 52% and −22% at fatigue limit of 36 MPa. The load-displacement hysteresis loops of the nano-modified SAJs showed higher fatigue stiffness compared to neat epoxy-SAJ. The stiffness of the SAJs was increased with increasing number of cycles up to about N/Nf = 0.01. As the number of cycles increases the damage level is increased and thus the slope of the hysteresis loop (stiffness) is decreased and the hysteresis loop area becomes wider. The highest penalty paid to gain safe lives was observed for Al2O3-SAJs, which has highest scatter in the fatigue lives.

      PubDate: 2017-04-11T10:43:00Z
       
  • Graphene nanoplatelets/carbon nanotubes/polyurethane composites as
           efficient shield against electromagnetic polluting radiations
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Meenakshi Verma, Sampat Singh Chauhan, S.K. Dhawan, Veena Choudhary
      Hybrid nanocomposites are in the forefront of nanomaterials research owing to their unique ability to enhance the material property due to the existing synergistic effect of the fillers. Here, we report a ternary hybrid nanocomposite comprising of thermoplastic polyurethane as matrix and graphene nanoplatelets-carbon nanotubes hybrid (GCNT) as filled inclusion. The solution blending approach was used to prepare a series of polyurethane nanocomposites with GCNT loading ranging from 0 to 10 wt%. Due to the synergistic interaction of the two kinds of nanofillers, an electrical conductivity of the order of ∼10−2 S/cm was achieved owing to the formation of a conducting network of CNTs bridging the gaps between graphene nanoplatelets throughout the electrically insulating polyurethane matrix. These hybrid nanocomposites exhibited excellent electromagnetic interference shielding up to −47 dB in the Ku-band of microwave frequency for 10 wt% loaded GCNT sample. In addition, the electromagnetic attributes, such as the real and imaginary permittivity of the nanocomposites as a function of frequency, were also investigated. The present studies, therefore, provides a new avenue for the preparation of hybrid carbon nanomaterials with unique structure and outstanding EMI shielding properties which make these materials as capable aspirants against electromagnetic polluting radiations.
      Graphical abstract image

      PubDate: 2017-04-11T10:43:00Z
       
  • Multiscale modeling of interphase in crosslinked epoxy nanocomposites
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Byungjo Kim, Joonmyung Choi, Seunghwa Yang, Suyoung Yu, Maenghyo Cho
      A multiscale modeling approach is proposed to characterize the interfacial behavior and the interphase properties of epoxy nanocomposites. The interfacial characteristics between the filler and matrix are investigated using molecular dynamics (MD) and molecular mechanics (MM) simulations. With increasing crosslink conversions, the interfacial adhesion between the filler and matrix is reduced which is attributed to the changes of inherent non-bond interaction characteristics at the interface, resulting in retarded reinforcing effect on the stiffness and thermal stability of epoxy nanocomposites. Moreover, to understand the structural change in the interphase region of nanocomposites with crosslinking, the radial density profile, the local crosslinks distribution, and the free volume at the filler surface are further examined. The results of structural features consistently demonstrate that the structural conformation of the interphase is substantially influenced by the reduction of interfacial communication with increasing crosslink conversion. In order to take into account the variations of interfacial compliance and the thermomechanical property of the interphase region, the effective interphase concept is implemented. Further, the micromechanics-based multi-inclusion model provides a reasonable prediction for the thermomechanical property of composites using the effective interphase concept.

      PubDate: 2017-04-11T10:43:00Z
       
  • Buckling, postbuckling and progressive failure analyses of composite
           laminated plates under compressive loading
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Ömer Namdar, Haluk Darendeliler
      In this study, buckling, post-buckling and progressive failure of composite laminated plates have been investigated numerically and experimentally. Buckling load, load-displacement relations for post buckling and maximum out-of-plane displacements of the plates are determined. Furthermore, the numerical results are compared with experimental findings for two different laminates made of woven fabric and uni-directional tapes. The comparisons show that there is a good agreement between numerical and experimental results obtained for buckling load and post-buckling behavior especially for the laminates with uni-directional tapes.

      PubDate: 2017-04-11T10:43:00Z
       
  • Stress/strain basis pairs for anisotropic materials
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Veysel Erel, Alan D. Freed
      The conjugate pair approach, when constructed from an upper-triangular decomposition of the deformation gradient, allows constitutive relations to be constructed without a need to introduce invariant theory. This approach to constitutive construction, previously proposed by the authors, is expanded upon in this paper to include anisotropic materials. Data acquired from 2D polyvinyl-ester composite panels, laid up with a single fiber orientation, are used to contrast the capability of our theoretical model with that of the transversely isotropic fiber model derived from invariant theory by Spencer.

      PubDate: 2017-04-11T10:43:00Z
       
  • Effect of heat treatment on the riveted joints of two-dimensional C/SiC
           composites
    • Abstract: Publication date: 1 July 2017
      Source:Composites Part B: Engineering, Volume 120
      Author(s): Hui Mei, Ding Zhang, Junchao Xia, Laifei Cheng
      A kind of riveting method for 2D C/SiC composites by chemical vapor infiltration were presented and the effect of heat treatment on the riveted joints of 2D C/SiC has been investigated through X-ray tests, mechanical tests, microstructural characterization and industrial computed tomography tests. The experimental results pointed that the order of heat treatment process and riveting process is a key factor affecting the micro-structures, total numbers of delamination defects, fiber pulling out length and tensile fracture strength of 2D C/SiC riveted joints. The heat treatment process after riveting can release assembly stress and residual thermal stress, and reduce the delamination defects in riveted joints, while the heat treatment process before riveting could increase the delamination defects and enlarge the braided holes in the riveted joints. The tensile strength increased by 23.2% when the riveted joints are riveted followed with heat treatment process, and the tensile strength of riveted joints decreased by 27.1% if the two processes are reversed.

      PubDate: 2017-04-11T10:43:00Z
       
  • Preparation of adipic acid-polyoxypropylene diamine copolymer and its
           application for toughening epoxy resins
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Xi Ren, Shumin Peng, Wei Zhang, Chunwang Yi, Yuan Fang, David Hui
      In this study, a series of adipic acid-polyoxypropylene diamine copolymer (AA-PPA) was prepared by copolymerizing polyoxypropylene diamine (PPA D400) and adipic acid (AA). The AA-PPA with weight-average molecular weight (M w) = 10400 and weight-average molecular weight (M n) = 7600 was used to modify diglycidyl ether of bisphenol A (DGEBA) epoxy/diethyl toluene diamine (DDM) system. This extended polyether AA-PPA showed unique advantages over traditional polyether at achieving the synchronous enhancement of strength and fracture toughness. With 30 wt% AA-PPA, the bending strength, tensile strength, elongation at break and impact strength were improved by 7.50%, 6.90%, 36.13% and 288.00%, respectively. The single glass transition temperature (T g) step proved the homogeneous phase structure of modified epoxy resins. Inevitably, the T g of modified epoxy decreased for the addition of soft segments. The dynamic mechanical analysis (DMA) results indicated that the storage modulus of modified epoxy increased with the increasing content of AA-PPA, while the loss modulus decreased. The interaction of the crosslinked network was explained by calculating the theoretical and measured values of the molecular weight between the crosslinks. The morphology showing the ductile fracture of modified epoxy was testified by scanning electron microscopy (SEM).

      PubDate: 2017-04-04T03:33:27Z
       
  • Influence of GFRP skin reinforcement on the crack evolution in RC ties
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Simona Coccia, Alberto Meda, Zila Rinaldi, Simone Spagnuolo
      Experimental tests on reinforced concrete ties with skin reinforcement made of Glass Fiber Reinforced Polymers (GFRP) mesh are presented in the paper. The study is a part of a wider research, currently going on at the University of Rome Tor Vergata, aimed at verifying possible solutions for limiting the crack opening, mainly in peculiar typologies of reinforced concrete structures, such as pipes or tunnel segments. Six 150 × 150 × 15000 mm3 specimens, with a steel Ø24 bar embedded in central position, were cast and tested under pure tension. In four ties a skin GFRP reinforcement was added, in order to analyse its influence on the crack spacing and width. Finally the application of a simple analytical model, suitably adapted for the analysed cases, shows the possibility of forecasting and simulating the crack patterns experimentally found.

      PubDate: 2017-04-04T03:33:27Z
       
  • Post-fire compressive behaviour of carbon fibers woven-ply Polyphenylene
           Sulfide laminates for aeronautical applications
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): M.A. Maaroufi, Y. Carpier, B. Vieille, L. Gilles, A. Coppalle, F. Barbe
      The influence of fire exposure on the residual compressive behaviors of carbon fibers woven-ply Polyphenylene Sulfide has been investigated for aeronautical applications. For heat fluxes ranging from 20 to 50 kW/m2, prior fire exposure is highly detrimental to the compressive mechanical properties as the residual strength and stiffness decrease by −75% and −55% respectively. Thermogravimetric analyses have been conducted under inert and oxidative atmospheres to quantify the mass loss resulting from the thermal decomposition of the outer layer directly exposed to heat flux and oxygen-rich atmosphere and internal layers respectively. Fire exposure results in gradually increasing damages within exposed laminates: PPS matrix thermal decomposition leaves intra- and inter-laminar voids leading to more or less extensive delamination depending on fire testing conditions. In order to discuss the compressive damage mechanisms after fire, the early deformation mechanisms have been analyzed by means of 2D Digital Image Correlation. C-scan inspections have also been performed to evaluate the delaminated areas which are quite well correlated with the surface fire-degraded areas, suggesting that delamination is primarily associated with thermal degradation. As heat flux increases, the fire-induced delamination and the onset of local plastic kink-bands during compressive loading ultimately cause delamination extension and global plastic buckling.

      PubDate: 2017-04-04T03:33:27Z
       
  • Fracture toughness (Mode I) characterization of SiO2 nanoparticle filled
           basalt/epoxy filament wound composite ring with split-disk test method
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Mehmet Turan Demirci, Necmettin Tarakçıoğlu, Ahmet Avcı, Ahmet Akdemir, İbrahim Demirci
      Matrix cracking which is the major initial form of damage in fiber reinforced polymer composites plays significant role in determining the fracture toughness. The fast crack propagation in polymer matrix causes to decrease the fracture toughness of fiber reinforced polymer (FRP) composite. In order to retard the fast crack propagation in polymer matrix and provide to increase of the fracture toughness of FRP composite, the polymer matrix of FRP composite is modified by filling the different kinds of nanoparticles. In such a way, the crack propagation leads to retard and dissipate the stress concentration affected to form the fiber cracks along of fibers in composite structure. In this study, basalt fiber was used as reinforcement material in ±[55]6 filament wound ring composite for creating the alternative to carbon, kevlar and glass fibers, to contribute to the research studies and literature. SiO2 nanoparticles that provides to form the effects of fracture toughness mechanism based on the effect of retarding crack propagation were filled into epoxy matrix to increase the mechanical properties and fracture toughness of ±[55]6 filament wound BFR/Epoxy ring composite. The split-disk tensile tests of single edge notched and un-notched ±[55]6 filament wound BFR/Epoxy ring composite specimens were conducted to determine the mechanical properties and mode I fracture toughness. SiO2 nanoparticle addition into epoxy matrix of ±[55]6 filament wound BFR/Epoxy ring composites has given the results of hoop tensile stress within the range of 27.7–30.3%. The fracture toughness of composite ring specimen was specified by ASTM E 399-12E3 by adapting to the directed mode I crack propagation and compared with each other. An effective increase in mode I fracture toughness of 43%–50% was obtained at 4 wt% addition level of SiO2 nanoparticles. The crack branching in epoxy matrix provided by SiO2 nanoparticle, matrix cracking, debonding, delamination and fiber breakage failures has been observed via microscope and SEM analysis.

      PubDate: 2017-04-04T03:33:27Z
       
  • On the wear properties of Nylon6-SiC-Al2O3 based fused deposition
           modelling feed stock filament
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Rupinder Singh, Narinder Singh, Ada Amendola, Fernando Fraternali
      Fused deposition modelling (FDM) is one of the commonly used additive manufacturing (AM) technologies. In commercial FDM setup a plastic material based filament (usually of ABS) is unwound from a coil to produce functional/non-functional prototypes. The application domain of FDM is limited presently, because of selective material availability in commercial market as regards to the wear of functional prototypes is concerned. In order to enhance the application domain of commercial FDM setup, an effort has been made to develop new polymer composite (with hybrid reinforcement) wire of Nylon6-SiC-Al2O3 with enhanced wear resistant properties. In this research work experimental investigations has been carried out for optimizing wear properties of Nylon6-SiC-Al2O3 based feed stock filament of FDM. Further mathematical model for above mentioned property has been developed and counter verified as a case study.

      PubDate: 2017-04-04T03:33:27Z
       
  • Analytical assessment of the bearing capacity of RC beams with corroded
           steel bars beyond concrete cover cracking
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Garyfalia G. Triantafyllou, Theodoros C. Rousakis, Athanasios I. Karabinis
      Corrosion of steel reinforcement is one of the major causes that limit durability and serviceability performance of reinforced concrete (RC) structures. This paper reviews thoroughly available experiments and analytical approaches in the relevant international literature and introduces a calculation model for assessing steel bar mass loss and contributes to further utilization of common in-situ inspections from a structural point of view. The model is based on the width of longitudinal crack of concrete cover, as a function of cover depth, bar diameter and mechanical properties of concrete. The model includes the well-known relationships for the steel mass loss during the first phase of rust formulation, filling the porous zone as well as during the phase that the radial pressure exceeds the concrete strength and causes cover cracking. The assumption followed herein for the flexibility of cracked concrete allows for the estimation of steel bar corrosion rate even beyond concrete cover cracking, by visual mapping of the width of longitudinal cracks. Then, the corresponding flexural capacity of the beams at yield and at maximum may be assessed. The predictions of the model are validated against 51 non-strengthened corroded beams and 24 strengthened corroded beams with Fiber Reinforced Polymer (FRP) materials published in the international literature.

      PubDate: 2017-04-04T03:33:27Z
       
  • Experimental analysis and micromechanical models of high performance
           renewable agave reinforced biocomposites
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): B. Zuccarello, R. Scaffaro
      The present work deals with the experimental study of high performance biocomposites reinforced with optimized agave fibers, as well as the successive implementation of reliable micromechanical models that can be used at the design stage. In detail, systematical experimental analyses performed on biocomposites with epoxy or PLA matrix, have permitted to highlight that for short fibers biocomposites the reinforcing leads to a significant improvement of the matrix stiffness, whereas the particular damage mechanism based essentially on the matrix failure with consequent tensile failure of the fibers aligned with the applied load, does not allow to obtain an actual reinforcing of the matrix. Such a result is strictly related to the limited fiber stiffness, that lead to a low reinforcing of the matrixes. Consequently, as confirmed by the experimental evidence, the mechanical performance of such biocomposites is not affected significantly by the improvement of the matrix-fiber adhesion provided by the mercerization. Also, the best results are obtained by using the stiffer agave marginata fibers, extracted by simple mechanical pressing of the leafs, without any successive treatment. For long fiber biocomposites, instead, the experimental analysis has shown that for a given fiber treatment, the use of the more deformable PLA allows a better exploiting of the fiber properties, i.e. it leads always to more eco-friendly biocomposites with higher mechanical strength. Moreover, the use of the agave marginata permits to obtain biocomposites with strength higher than the biocomposites reinforced with the common agave sisalana (sisal), with improvements until to about 50%; also, the use of fibers extracted by simple leafs pressing, allows the user to obtain high performance renewable biocomposites, characterized by high stiffness and strength comparable with that obtained by using mercerized fibers. Finally, the detailed analysis of the damage mechanisms, performed also by proper 2D and 3D micrographs, has permitted to implement accurate theoretical models that allows the user accurate predictions of the mechanical performance of biocomposites reinforced with short fibers or long fibers.

      PubDate: 2017-04-04T03:33:27Z
       
  • Durability of bonded FRP-to-steel joints: Effects of moisture, de-icing
           salt solution, temperature and FRP type
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Mohsen Heshmati, Reza Haghani, Mohammad Al-Emrani
      This paper investigates the effects of environmental ageing on the mechanical response of adhesively bonded double-lap shear joints made of steel and CFRP or GFRP adherents. One hundred and ninety-two specimens, 84 joints and 108 material coupons, were aged for up to three years in various environments including (i) immersion in distilled water at 20 °C and 45 °C, (ii) immersion in de-icing salt solution at 20 °C and 45 °C and (iii) exposure to 95% relative humidity at 45 °C. In general, immersion at 45 °C resulted in noticeably greater strength reductions at both material and joint level. While the strength and stiffness of the joints made of GFRP material underwent significant reductions, the CFRP/steel joints were affected to a considerably smaller degree. FE simulations showed the impact of the permeability of FRP adherents and moisture distribution at the FRP/adhesive interface on the integrity and strength of the joints. The joint-level results are compared with the most relevant durability data in the literature.

      PubDate: 2017-04-04T03:33:27Z
       
  • Mesoscale modelling of tensile response and damage evolution in natural
           fibre reinforced laminates
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Zia Mahboob, Yves Chemisky, Fodil Meraghni, Habiba Bougherara
      A continuum damage mechanics based mesoscale model is developed within a thermodynamics framework to describe the in-plane tensile response in natural fibre composites. The standard Mesoscale Damage Theory (MDT) is modified to incorporate damage and inelasticity evolution in the fibre-direction, thereby capturing the unique nonlinear fibre-direction response evidenced in natural fibre composites (NFC). The multi-ply damage model is validated using tests on Flax/epoxy laminates and available data on Carbon/epoxy laminates. Model parameters are identified for Flax/epoxy by applying an optimisation algorithm that compares numerical predictions with experimental data. Predictions of mechanical response, stiffness degradation, and inelasticity correlate very well with experimental observations of Flax-laminates. This modified-MDT model offers a predictive, robust tool to aid the development of NFC engineering structures.

      PubDate: 2017-04-04T03:33:27Z
       
  • Modeling and analysis of out-of-plane behavior of curved nanobeams based
           on nonlocal elasticity
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Serhan Aydin Aya, Ekrem Tufekci
      The purpose of this study is to analytically investigate the out-of-plane static behavior of curved nanobeams with non-uniform distributed loads. Nonlocal constitutive equations are implemented into the governing equilibrium equations in cylindrical coordinates. Use of these equations enables revealing the scale effect on static response of curved nanobeams. Shear deformation is considered in the formulation of out-of-plane static behavior of nanobeams. The exact analytical solution to the theoretical model is derived by using initial value method. The fundamental matrix required for the initial value method is obtained analytically. Then, the displacement, slopes and stress resultants are found analytically using the fundamental matrix. Illustrative examples for such nano structures with non-uniform distributed loads are given in subsequent sections. Results showed that the scale effect plays crucial role at nano scale which agree with the results given in the literature. The effects of small scale parameter, slenderness ratio and opening angle on the displacements ratio, rotation angles ratio and stress resultants ratio are also investigated in details. Considering scale effect and shear deformation in the exact solutions of the governing equilibrium equations presented here, the results can be considered as a reference for nonlocal theories of curved nanobeams.

      PubDate: 2017-04-04T03:33:27Z
       
  • Experimental investigation of fatigue damage formation of hybrid pipes
           subjected to impact loading under internal pre-stress
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Lokman Gemi, Ömer Sinan Şahin, Ahmet Akdemir
      In this study, the effect of impact loading upon fatigue behavior of hybrid composite pipes has been investigated. The composite pipes were subjected to tangential pre-stress as 3–48 MPa according to ANSI/AWWA C950 standard than, subjected to low velocity impact at 20 J. The impact pre-damaged pipes then subjected to cyclic loading at 50% σult in accordance with ASTM D 2992-06. It is also observed that increasing the tangential pre-stress decreases impact damage area and increases fatigue life of the pipe. It is also showed that impact pre-damage are not effective on the fatigue life of the pipe at the pre-stress level of 24 MPa.

      PubDate: 2017-04-04T03:33:27Z
       
  • Estimating fatigue reliability of structural components via a
           Birnbaum-Saunders model with stress dependent parameters from accelerated
           life data
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Giuseppe D'Anna, Massimiliano Giorgio, Aniello Riccio
      In this paper, the interest is in estimating the fatigue life distribution of highly reliable structural components from data obtained via accelerated life tests. These tests consist in subjecting the products of interest to stress levels more severe than those encountered in normal use. This forces the considered products to fail more quickly and allows collecting failure data in a reasonably short amount of time. Estimates of the product's reliability at normal use conditions are then extrapolated from accelerated failure data by adopting proper models. The model proposed in this paper generalizes a model which is widely applied in literature to analyze accelerated fatigue life data. In fact, as the abovementioned standard model it relies on two very classical assumptions, namely: a) the test conditions affect the lifetime distribution parameters, and not its form, and b) the fatigue life at each considered stress level follows a Birnbaum-Saunders distribution. On the other side, differently from the standard model, in which only the scale parameter depends on the stress conditions, the proposed model assumes that both the parameters of the Birnbaum-Saunders distribution possibly depend on the stress. The model is applied to a real set of accelerated fatigue failure data. Model parameters are estimated via the maximum likelihood method. The estimate of the reliability function at normal use conditions is extrapolated from the accelerated data. It is shown that the proposed Birnbaum-Saunders based model, in which both scale and shape parameters depend on the stress conditions, fits the considered data better than the model usually adopted in the literature. Differences among results provided by the two considered alternative models are highlighted and discussed. Finally two graphical strategies are proposed that allow judging the goodness of fit of the proposed model in absolute terms.

      PubDate: 2017-04-04T03:33:27Z
       
  • Advanced models for smart multilayered plates based on Reissner Mixed
           Variational Theorem
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): I. Benedetti, A. Milazzo
      In the present work, families of equivalent singe layer and layer-wise models for the static and free vibrations analysis of magneto-electro-elastic multilayered plates are developed. The models are defined in the framework of a unified formulation, which offers a systematic approach for generating refined plate theories through suitable expansions of the through-the-thickness components of the relevant fields, considering the expansion order as a free parameter. The key features of the developed formulation are: a) the condensation of the electric and magnetic description into the mechanical representation, based on the quasi-static electric-magnetic approximation, which allows to reduce the computation of the analysis for both layer-wise and equivalent single layer models; b) the employment of the Reissner Mixed Variational Theorem, in which the displacements and transverse stress components are used as primary variables, thus allowing the explicit fulfilment of the transverse stress interface equilibrium. The proposed methodology is assessed by generating different layer-wise and equivalent single layer models for the analysis of thick magneto-electro-elastic plates and comparing their solution against available three-dimensional analytic results.

      PubDate: 2017-04-04T03:33:27Z
       
  • Implementation and calibration of meso-scale modeling technique for
           simulation of tensile behavior of fabric materials
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): E. Giannaros, T. Kotzakolios, S. Tsantzalis, V. Kostopoulos
      Present paper investigates the simulation of quasi-static response of fabric materials subjected to uniaxial tensile loading. The purpose of this research is to simulate the fabrics mechanical behavior accurately determining the quasi-static elastic and failure properties of fabric yarn and to rank, from the analysis point of view, the parameters which influence the fabric behavior. In particular, a meso-scale approach was employed to model the behavior of different para-aramid fabrics using LS-DYNA software whereas the Nelder & Mead Simplex optimization algorithm was implemented for the determination of material model's parameters by the fitting of numerical and experimental tensile loading curve.

      PubDate: 2017-03-27T10:47:08Z
       
  • Thermal resistant, mechanical and electrical properties of a novel
           ultrahigh-content randomly-oriented CNTs reinforced SiC matrix
           composite-sheet
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): L.W. Yang, X.S. Zhang, H.T. Liu, M. Zu
      Development of a thermal resistant CNT based sheet is important for high temperature engineering perspectives with multifunctional purposes. This work reports a novel CNT reinforced SiC matrix composite-sheet by polymer derived ceramics (PDC) processes using polycarbosilane as SiC precursor. The microstructure contains the amorphous SiC matrix (4 phases: SiC, SiCxOy, SiO2 and free carbon), the chemical sharp CNT/SiC interfaces and the ultrahigh density multi-walled CNTs that are randomly oriented. The composite-sheet is thermally and mechanically stable in non-oxidizing atmosphere up to 1000 °C. The mechanical properties of the composite-sheet are significantly enhanced, with the Young's modulus increased by ∼7 times, and the tensile strength ∼4 times, compared to those of pure CNT sheet. The strengthening mechanism is a bridging effect of the SiC matrix to the CNTs to favor better load transfers during fracturing. Therefore, the composite-sheet shows an elastic-brittle fracture response, with limited CNT pull-out in the fracture surface after tensile test. Finally, the composite-sheet shows an excellent electrical conductivity that is also comparable to the pure CNT sheet, and is found enhanced after post heat-treatment at temperatures >800 °C in non-oxidizing atmosphere, presumably due to the more content free carbon formations in the SiC matrix.

      PubDate: 2017-03-27T10:47:08Z
       
  • Analytical study for the development of a new warping function for high
           order beam theory
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Ismail Mechab, Noureddine El Meiche, Fabrice Bernard
      This paper presents an analytically and numerical study of the warping phenomenon in short beams, thick plates and anisotropic materials. A transverse shear higher order theory is considered. The equilibrium equations are inspired by the principle of virtual work that has permitted to establish the boundary conditions. The analytical development of a new warping function is inspired by others works found in the literature for three-point bending. The stabilization of this new iterative function under a uniformly distributed pure bending load is used for any type of structure. Analytical results are compared with other existing models in the literature and a simulation using the finite element method.

      PubDate: 2017-03-27T10:47:08Z
       
  • Low percolation threshold and electromagnetic shielding effectiveness of
           nano-structured carbon based ethylene methyl acrylate nanocomposites
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Subhadip Mondal, Sayan Ganguly, Poushali Das, Dipak Khastgir, Narayan Ch Das
      In the present work, we developed industrially scalable and affordable Ketjen carbon black (K-CB)-ethylene methyl acrylate copolymer (EMA) composites with low percolation threshold and efficient electromagnetic interference (EMI) shielding efficiency associated with high potential of absorption dominance of electromagnetic (EM) radiations by conductive dissipation. The dispersion and distribution of K-CB inside the EMA elastomer have been affirmed with the help of qualitative electron micrograph techniques. The EMA matrix and K-CB filler interactions have been corroborated through bound rubber content and dynamic mechanical properties. Interfacial interactions between K-CB and polymer matrix are pivotal in determining the good reinforcing efficiency with tunable electrical conductivity as well as adjustable EMI shielding ability in K-CB filled composites. The proposed composites lead to a low percolation threshold (8.6 wt%) and promising high EMI shielding value of 33.9 dB for 20 wt% K-CB in the X-band frequency as compared to other expensive carbon fillers. On account of the thorough analysis of the composites, our high hopes have been placed on the promotion of low budget and flexible EMA/K-CB composite for the emerging field of superior EMI shielding applications.
      Graphical abstract image

      PubDate: 2017-03-27T10:47:08Z
       
  • Comparative study of graphene nanoparticle and multiwall carbon nanotube
           filled epoxy nanocomposites based on mechanical, thermal and dielectric
           properties
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Muhammad Razlan Zakaria, Muhammad Helmi Abdul Kudus, Hazizan Md. Akil, Mohd Zharif Mohd Thirmizir
      Nano-sized carbons, such as graphene nanoparticle (GNP) and multiwall carbon nanotube (MWCNT), have attracted a great deal of attention due to their extraordinary intrinsic properties. Extensive research has been done on each carbon material for epoxy nanocomposites but only a few have ventured into a comparison study. In this paper, the effect of GNP and MWCNT, at various filler loadings, on the mechanical, thermal and dielectric properties of epoxy nanocomposites have been investigated. The experimental results demonstrate that GNP filled epoxy nanocomposites showed higher thermal and dielectric properties, but slightly lower mechanical properties compared to the MWCNT filled epoxy nanocomposites. The tensile strength, flexural strength, thermal conductivity and dielectric constant of GNP filled epoxy nanocomposites improved up to 11%, 17%, 126%, and 171% respectively, and MWCNT filled epoxy nanocomposites improved up to 26%, 29%, 60%, and 73% respectively.

      PubDate: 2017-03-27T10:47:08Z
       
  • Buckling and postbuckling of functionally graded graphene-reinforced
           composite laminated plates in thermal environments
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): Hui-Shen Shen, Y. Xiang, Feng Lin, D. Hui
      Modeling and analysis of the postbuckling behavior of graphene-reinforced composite (GRC) laminated plates are presented in this paper. The GRC plates are in a thermal environment, subjected to uniaxial compression and resting on an elastic foundation. The temperature-dependent material properties of functionally graded graphene-reinforced composites (FG-GRCs) are assumed to be graded in the plate thickness direction with a piece-wise type, and are estimated through a micromechanical model. The postbuckling problem of FG-GRC laminated plates is modeled using a higher order shear deformation plate theory and the plate-foundation interaction and thermal effects are taken into consideration. A two-step perturbation technique is employed to determine the buckling loads and the postbuckling equilibrium paths. The compressive buckling and postbuckling behavior of perfect and imperfect, geometrically mid-plane symmetric FG-GRC laminated plates under different sets of thermal environmental conditions is obtained and is also compared with the behavior of uniformly distributed GRC laminated plates. The results show that the buckling loads as well as the postbuckling strength of the GRC laminated plates may be enhanced through piece-wise functionally graded distribution of graphene.

      PubDate: 2017-03-27T10:47:08Z
       
  • Sol-gel temperature dependent ductile-to-brittle transition of
           aluminosilicate fiber reinforced silica matrix composite
    • Abstract: Publication date: 15 June 2017
      Source:Composites Part B: Engineering, Volume 119
      Author(s): L.W. Yang, J.Y. Wang, H.T. Liu, R. Jiang, H.F. Cheng
      A thorough understanding in the micro mechanical properties of the fiber, the fiber/matrix and the matrix of the composite material, especially in response to different processing temperatures, is critical to explore the strengthening and toughening mechanisms of the novel oxide fiber reinforced oxide ceramic matrix composites. This work contributes this by studying the sol-gel temperature dependent micro mechanical properties of an aluminosilicate fiber reinforced silica matrix composite using novel nano-mechanical methods like nanoindentation and push-in techniques. In the sol-gel temperature range of 600–1200 °C, the aluminosilicate fiber was comparably stable in mechanical properties, though a microstructure transition from amorphous SiO2+ γ-Al2O3 to crystallized mullite+γ-Al2O3 was found at 1000 °C. The silica matrix was amorphous in microstructure, but were more crystallized as the sol-gel temperature increased, which subsequently led to an enhanced mechanical property at higher temperature. The interfacial shear strength was small in the temperature range of 600–1000 °C, and was increased slightly from ∼50 MPa at 600 °C to ∼84 MPa at 1000 °C. The interfacial shear strength at 1200 °C was high (∼256 MPa), due to the interfacial reaction occurring at this temperature. Correlating these micro mechanical properties to the macro fracture resistance that was quantified by the three-point bending test, an interface mediated toughening mechanism was finally concluded to explain the sol-gel dependent fracture resistance of the composite and the ductile-to-brittle transition observed in the temperature range.

      PubDate: 2017-03-27T10:47:08Z
       
  • Vibration analysis of quadrilateral graphene sheets subjected to an
           in-plane magnetic field based on nonlocal elasticity theory
    • Abstract: Publication date: 1 June 2017
      Source:Composites Part B: Engineering, Volume 118
      Author(s): L.W. Zhang, Yang Zhang, K.M. Liew
      Graphene sheets have wide application, in which the integration of multiple disparate fields for the realization of expanded functionalities is of great significance. This study investigates the vibration behavior of quadrilateral single-layered graphene sheets (SLGSs) in a magnetic field using classic plate theory and incorporating nonlocal elasticity theory, concerning the small scale effect. The element-free kp-Ritz method is employed to perform the numerical simulation. The efficiency of the proposed numerical tool is verified by published results. The effect of nonlocal parameters, skew angles, magnetic parameters and boundary conditions on the vibration behavior of parallelogram SLGSs is studied. The results show that skew angles and the magnetic field help increase the fundamental frequencies of SLGSs, which indicates the potential application of SLGSs as highly sensitive mass detectors. Moreover, 14 different quadrilateral SLGSs, with different nonlocal parameters and magnetic parameters for different boundary conditions, are simulated.

      PubDate: 2017-03-27T10:47:08Z
       
  • 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
           application
    • 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
           reinforcements
    • 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
       
 
 
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