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  Subjects -> ENGINEERING (Total: 2268 journals)
    - CHEMICAL ENGINEERING (190 journals)
    - CIVIL ENGINEERING (183 journals)
    - ELECTRICAL ENGINEERING (103 journals)
    - ENGINEERING (1201 journals)
    - ENGINEERING MECHANICS AND MATERIALS (380 journals)
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    - MECHANICAL ENGINEERING (89 journals)

ENGINEERING (1201 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 17)
AAPG Bulletin     Hybrid Journal   (Followers: 7)
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: 247)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 8)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
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: 26)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 29)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 38)
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: 31)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 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: 17)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 16)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 1)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
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: 8)
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: 8)
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: 5)
Batteries     Open Access   (Followers: 5)
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: 4)
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: 10)
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: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 32)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
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: 10)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 24)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 43)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
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: 7)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 8)
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: 22)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
Coatings     Open Access   (Followers: 4)
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: 26)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 265)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 188)
Composites Part B : Engineering     Hybrid Journal   (Followers: 278)
Composites Science and Technology     Hybrid Journal   (Followers: 182)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 14)
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: 7)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
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: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 30)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 7)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 42)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
CT&F Ciencia, Tecnologia y Futuro     Open Access   (Followers: 1)
CTheory     Open Access  

        1 2 3 4 5 6 7 | Last

Journal Cover Composites Part B : Engineering
  [SJR: 2.125]   [H-I: 75]   [278 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1359-8368
   Published by Elsevier Homepage  [3048 journals]
  • Vibroacoustic behavior of full-scale sandwich floor with softened
           graphite-incorporated expanded polystyrene core
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Hyo Seon Park, Byung Kwan Oh, Tongjun Cho
      Previous laboratory-scale research has shown that the post-yield softening of graphite-incorporated expanded polystyrene (EPS) foam has the unique property of vibroacoustic insulation for low-frequency floor impacts. However, the core softening causes decoupled behaviors in the sandwich floor, and thus, the improvement in insulation may deteriorate at some frequencies. To understand how core softening actually affects the insulation performance in real-life building structures, the vibroacoustic behaviors of sandwich floors with softened graphite-incorporated EPS cores was studied through a full-scale experimental investigation. The results indicate that core softening lowers the degree of coupling between the upper and lower plates, shifts the coupled and decoupled modes of the floor to lower frequencies, and develops decoupled modal wave fields in the upper plate. The frequency and amplitude of the sound produced by modal behavior of the sandwich floor vary in accordance with the vibration response of the lower plate, which depends on the changes in the structural wave field with core softening. Furthermore, the shift in the structural modal frequency with core softening affects the modal coupling between the structural and acoustic domains.

      PubDate: 2017-11-16T03:09:41Z
       
  • Design criteria of multilayer fibers reinforced composite in bulky 3D
           loaded applications
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): K. Hamza, A.Y. Shash, M. Abdrabou
      In this research paper the design criteria of 3D loaded bulky shapes made from multilayer short carbon fibers reinforced epoxy using compression molding is studied. Five different design criteria are discussed with different limiting stress and strain values. The first criterion is based on the fibers local stresses; the second criterion depends on the interfacial bonding strength; the third criterion is the conventional failure one derived from the composite average strength. In addition to this the Hashin damage criteria are applied on the fiber and matrix of the composite. The mathematical models of the short fibers reinforced composites strength and interfacial bonding strength are reviewed. A finite element model is introduced to estimate the local stresses on the fibers, interfacial bonding stresses between the fibers and matrix, and the average composite stresses. The finite element model is checked on a representative volume element (RVE) of the composite with general fibers orientation and loading direction. The results obtained from the FEA analysis is used to check the design with the five design criteria, and compared with the tensile specimen from the experimental work as well. Finally, the finite element analysis and design criteria are applied on a 3D loaded bulky shape used in plumbing inspection chambers made from short fiberglass filled calcium carbonate reinforced polyester. The validated model and design criteria are checked on the results of the inspection chamber results.

      PubDate: 2017-11-16T03:09:41Z
       
  • On the dynamics of non-local fractional viscoelastic beams under
           stochastic agencies
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Gioacchino Alotta, Mario Di Paola, Giuseppe Failla, Francesco Paolo Pinnola
      Non-local viscoelasticity is a subject of great interest in the context of non-local theories. In a recent study, the authors have proposed a non-local fractional beam model where non-local effects are represented as viscoelastic long-range volume forces and moments, exchanged by non-adjacent beam segments depending on their relative motion, while local effects are modelled by elastic classical stress resultants. Long-range interactions have been given a fractional constitutive law, involving the Caputo's fractional derivative. This paper introduces a comprehensive numerical approach to calculate the stochastic response of the non-local fractional beam model under Gaussian white noise. The approach combines a finite-element discretization with a fractional-order state-variable expansion and a complex modal transformation to decouple the discretized equations of motion. While closed-form expressions are derived for the finite-element matrices associated with elastic and fractional terms, fractional calculus is used to solve the decoupled equations of motion, in both time and frequency domain. Remarkably, closed-form expressions are obtained for the power spectral density, cross power spectral density, variance and covariance of the beam response along the whole axis. Time-domain solutions are obtained by time-step numerical integration methods involving analytical expressions of impulse response functions. Numerical examples show versatility of the non-local fractional beam model as well as computational advantages of the proposed solution procedure.

      PubDate: 2017-11-16T03:09:41Z
       
  • An incremental inverse analysis procedure for identification of bond-slip
           laws in composites applied to textile reinforced concrete
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Yingxiong Li, Jan Bielak, Josef Hegger, Rostislav Chudoba
      Textile reinforced concrete (TRC) is a novel composite building material, its structural behavior is substantially influenced by the bond interface between the reinforcing textile fabrics and concrete. The bond interface can be characterized by a nonlinear bond-slip law. The pull-out test is a common experimental procedure for determination of the bond-slip law. In this paper, a general finite element procedure is proposed to calibrate the bond-slip law according to the results of pull-out tests. By adopting a generic multilinear bond-slip law and solving each piece of the law sequentially, the conventional curve fitting procedures employing optimization algorithms, which are computationally expensive and sometimes non-convergent, can be avoided. Pull-out tests of TRC specimens with varying anchorage lengths were carried out and the test results were used as the input data for the calibration procedure. It is found that the calibrated bond-slip law is independent of the specimen length. Using the calibrated bond-slip laws, the pull-out force vs. displacement curves are numerically reproduced. The numerical results agree well with the experimental data.

      PubDate: 2017-11-16T03:09:41Z
       
  • Seventh-year durability evaluation of zinc borate incorporated
           wood-plastic composites and particleboard
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Cihat Tascioglu, Kenji Umemura, Tsuyoshi Yoshimura
      Several formulations of wood-plastic composites and a particleboard were fabricated with combining zinc borate biocide at different retention levels during the manufacturing process. The treated specimens were exposed to a field test under protected above ground conditions for 7 years in southern Japan. During biannual inspections, the specimens were visually inspected and graded for decay and Formosan subterranean termite damage. While zinc borate retention levels tested were able to protect the particleboards from decay activity for 7 years, their efficacy was lower against termite attack. The retention levels tested up to 2% (w/w) helped to reduce termite damage noticeably but failed from full protection (e.g. rating 10) indicating higher zinc borate loadings are required in particleboards if they will be utilized in southern Japan climatic conditions. Wood-plastic composites were also more durable against fungal damage during the 7 years exposure period but this condition seems changed last 18 months since some lower decay ratings were recorded even for zinc borate embedded formulations. While termite destruction diminished significantly with zinc borate integrated formulations, higher retentions might be recommended as threshold for full protection in wood-polypropylene composites.

      PubDate: 2017-11-16T03:09:41Z
       
  • Polyaniline-metal organic framework nanocomposite as an efficient
           electrocatalyst for hydrogen evolution reaction
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Kabelo Edmond Ramohlola, Gobeng Release Monana, Mpitloane Joseph Hato, Kwena Desmond Modibane, Kerileng Mildred Molapo, Milua Masikini, Siyabonga Beizel Mduli, Emmanuel I. Iwuoha
      Polyaniline-metal organic framework (PANI/MOF) composite was prepared by chemical oxidation of aniline monomer in the presence of 3.6 wt% MOF content for hydrogen evolution reaction (HER). The structure, morphology and properties of the fabricated composite were investigated. There was a clear interaction of MOF on the backbone of the PANI matrix through electrostatic interaction as investigated by both Raman and Fourier transform infrared analyses. The MOF exhibited irregular crystals with further wrapping of MOF by PANI matrix as evidenced by both scanning electron microscopy and transmission electron microscopy studies. The PANI composite showed some nanorods and microporous structure. The energy band gap values of PANI and its composite were found to be 1.50 and 1.35 eV, respectively. The thermal stability of the neat PANI increased upon composite formation, which was due to a stabilizing effect of MOF and a change in morphology of the composite. The catalytic effect of MOF, PANI and PANI/MOF composite on HER was studied using exchange current density (i 0) and charge transfer coefficient determined by the Tafel slope method. A drastic increase in catalytic H2 evolution was observed in the composite. In addition, the Tafel slope values of PANI and the composite decreased with increasing the concentration of the acid, suggesting the Volmer reaction coupled with either Heyrovsky or Tafel reaction. The i 0 increased with increasing the acid concentration and in an order of PANI/MOF > MOF > PANI at various concentrations.

      PubDate: 2017-11-16T03:09:41Z
       
  • Weldability of thermoplastic materials for friction stir welding- A state
           of art review and future applications
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Ranvijay Kumar, Rupinder Singh, I.P.S. Ahuja, Rosa Penna, Luciano Feo
      Polymer composites have certain advantages over metals in terms of mechanical as well as metallurgical properties. These can be joined with similar as well as dissimilar polymer composites (subject to certain conditions like glass transition temperature, rheological properties etc.). In last 20-25 years number of techniques and concepts has been developed to offer the possibility of joining of polymeric materials which have similar or dissimilar characteristics. In present scenario mechanical fastening and adhesive bonding is replaced by applying welding concepts like: laser transmission welding, friction stir welding (FSW), ultrasonic welding, hot fusion resistance welding etc. The FSW is one of the most acceptable welding techniques for production of structural/industrial components. In this present work, requirements of FSW and its process capability has been highlighted for joining of similar/dissimilar polymeric materials for future prospective.

      PubDate: 2017-11-09T08:35:07Z
       
  • Extending the value chain of corn agriculture by evaluating technical
           feasibility and the quality of the interphase of chemo-thermomechanical
           fiber from corn stover reinforced polypropylene biocomposites
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): M. Delgado-Aguilar, F. Vilaseca, Q. Tarrés, F. Julián, P. Mutjé, F.X. Espinach
      With the increasing concerns towards the environment, industries are interested in substituting glass fibers by natural fiber. Nonetheless, filaments or strands from jute, hemp or abaca, are mainly used as reinforcement. Such fibers are, in some cases, more expensive than the glass fibers that are replacing. Grain corn harvest creates a huge amount of by-products in the shape of corn stover. These stover usually remains in the field to be incinerated, or recovered to prepare feedstuff, or bedding for livestock. Besides, corn is a globally spread crop, and consequently, corn stover becomes available as renewable source for reinforcing fibers. The aim and main novelty of the research is transforming a by-product as corn stover into a cheap source of reinforcing fibers to obtain competitive biocomposites. To do so, such biocomposites must show mechanical properties comparable to those materials currently present in the market. In this work, biocomposites reinforced with natural fibers from corn stover are used as reinforcement of polypropylene; their mechanical properties are investigated and compared. Moreover, the interphase between the reinforcement and the matrix is also modelled by means of the Kelly and Tyson equation to assess its quality.

      PubDate: 2017-11-09T08:35:07Z
       
  • Low-temperature fabrication of SiC/geopolymer cellular composites
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Chengying Bai, Jian Zheng, Gian Andrea Rizzi, Paolo Colombo
      Hierarchically porous SiC-geopolymer foams were synthesized by using geopolymerization, which is a low temperature method (75 °C) that allows to replace the high temperature treatment process. The porosity was developed by a novel saponification/peroxide combined route, with H2O2 and olive oil used as foaming agents. The in-situ formation of the water-soluble soap and glycerol molecules generated by the saponification reaction and the decomposition of hydrogen peroxide enabled to obtain a large volume of interconnected macro-porosity. The reaction bonding behavior, phase composition, porosity characteristics, microstructure and mechanical strength of porous SiC-geopolymer ceramics were investigated. The combination of peroxide and oil enabled the production of open celled SiC-geopolymer composite foams in a rather large range of total porosity and strength values, with an optimal sample possessing a total porosity of up to ∼84 vol%, an open porosity of ∼83 vol%, a thermal conductivity of 0.15 W/mK, and a compression strength of ∼1.1 MPa.

      PubDate: 2017-11-09T08:35:07Z
       
  • Waterborne polyurethane-urea dispersion with chain extension step in
           homogeneous medium reinforced with cellulose nanocrystals
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Arantzazu Santamaria-Echart, Isabel Fernandes, Lorena Ugarte, Filomena Barreiro, Aitor Arbelaiz, Maria Angeles Corcuera, Arantxa Eceiza
      Waterborne polyurethane-urea (WBPUU) dispersions have gained attention towards environmentally-friendly synthesis routes. Differing from the conventional WBPUU synthesis route where the diamine chain extension is performed in heterogeneous medium in the surface of the already formed particles, in this case the chain extension was carried out in homogeneous medium, prior to WBPUU nanoparticles formation. Thus, stable WBPUU dispersion with small particle sizes and narrow distribution was synthesized. Furthermore, cellulose nanocrystals (CNC) were isolated for the preparation of eco-friendly nanocomposites just by mixing. Nanocomposites with different CNC contents were prepared and extensively characterized in terms of physicochemical, thermal, thermomechanical and mechanical properties, hydrophilic behavior and morphology.

      PubDate: 2017-11-09T08:35:07Z
       
  • Analysis of composite layered beams using Carrera unified formulation with
           Legendre approximation
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): M.R.T. Arruda, L.M.S. Castro, A.J.M. Ferreira, M. Garrido, J. Gonilha, J.R. Correia
      This paper presents some numerical investigations related to the use of a new approximation function to be applied in Carrera's Unified Formulation (CUF). The main objective is to study and assess the efficiency of the CUF, when Legendre approximation functions are used at the section level, on 1D element, using an equivalent single layer (ESL) formulation. Previous experimental and analytical results, obtained in the case of GFRP composite bridge decks and sandwich panels, are used to further validate the numerical results being reported. 3D finite elements are also used, in order to compare and validate the numerical structural outputs. The main conclusion is that the classical Legendre polynomial functions are suitable and provide accurate results. The use of this type of functions does not require any stabilization procedure of the resulting governing system for the case of 1D elements, in clear contrast to what typically happens when other approximation functions are used with an equivalent single layer formulation.

      PubDate: 2017-11-09T08:35:07Z
       
  • Interfacial bonding strength of short carbon
           fiber/acrylonitrile-butadiene-styrene composites fabricated by fused
           deposition modeling
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Wei Zhang, Chase Cotton, Jessica Sun, Dirk Heider, Bohong Gu, Baozhong Sun, Tsu-Wei Chou
      This work aims to characterize the interfacial bonding strength between printed wires of acrylonitrile-butadiene-styrene (ABS), carbon nanotube reinforced ABS (CNTABS) and short carbon fiber reinforced ABS (CFABS) specimens fabricated by fused deposition modeling. The in-plane tensile shear test and double notch shear test methods using ±45° specimens were used. The in-plane tensile shear strength of CFABS specimen is close to that of CNTABS specimen, and both of them are greater than that of ABS specimen. Double notch shear strengths are smaller than in-plane tensile shear strength of CFABS specimens at all three printing speeds studied. Also, the shear strengths of CFABS specimens decrease with increasing printing speed and layer thickness. X-ray micro-computed tomography examination concluded that CFABS specimens have the largest porosity compared with ABS and CNTABS specimens at corresponding raster orientation, especially for ±45° specimens. Matrix fracture and fiber pull-out, as well as fiber-matrix interfacial debonding are the dominating failure modes of CFABS specimen.

      PubDate: 2017-11-09T08:35:07Z
       
  • Noncoaxial vibration and buckling analysis of embedded double-walled
           carbon nanotubes by using doublet mechanics
    • Abstract: Publication date: 15 March 2018
      Source:Composites Part B: Engineering, Volume 137
      Author(s): Ufuk Gul, Metin Aydogdu
      Free vibration and buckling of double-walled carbon nanotubes embedded in an elastic medium with simply supported boundary conditions are studied. Doublet Mechanics (DM) is used in the analysis. Macro level strains and stresses are defined in terms of micro level strains and stresses in the DM theory. These micro deformations and micro stresses are expanded in Taylor series and the number of terms in the Taylor series defines degree of the approach. Double-walled carbon nanotubes are modelled as Euler-Bernoulli beams embedded in an elastic medium. Critical buckling loads and free vibration frequencies are obtained by using DM and compared with the classical elasticity solutions. It is obtained that for some frequencies carbon nanotubes move noncoaxially. Noncoaxial vibration and buckling affect the physical properties of carbon nanotubes. The present results show that a length scale dependent DM can be used in the design of nano electro-mechanical systems.

      PubDate: 2017-11-09T08:35:07Z
       
  • Impact analysis of CNT-reinforced composite plates integrated with
           piezoelectric layers based on Reddy's higher-order shear deformation
           theory
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): B.A. Selim, B.B. Yin, K.M. Liew
      As a first endeavor in the open literature, the impact analysis of carbon nanotube reinforced composite (CNTRC) plates integrated with piezoelectric layers is studied. In this paper, a novel element-free IMLS-Ritz model with Reddy's higher-order shear deformation theory is employed considering four distributions of carbon nanotubes. The effective material properties of the CNTRC plates are estimated by the Mori-Tanaka method. The modified non-linear Hertz contact law is utilized to define the contact force between the target CNTRC plates integrated with piezoelectric layers and the spherical impactor during the impact duration. Newmark time integration method is employed to identify the dynamic response of the target plates and the impactor displacement. The impactor is assumed to strike the target plate either at CNTRC layer or the piezoelectric one. Novel results for the two cases are presented.

      PubDate: 2017-11-09T08:35:07Z
       
  • Functional dendritic curing agent for epoxy resin: Processing, mechanical
           performance and curing/toughening mechanism
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Chunhua Lou, Xijun Liu
      A functional curing agent was synthesized with imidazole blocked 2,4-tolulene diisocyanate (TDI) by using dendritic polyester polyol as branching unit and toughening segment, which toughening and curing the bisphenol A type epoxy resin (E−44). The effect of dendritic polyester polyol content on the morphology of fracture surface and properties of the cured epoxy resin was investigated, which results in the multiple curing mechanism for the curing process. With the increasing of dendritic polyester polyol content, the surface fracture of the cured epoxy turns to more ductile. The mechanical properties from tensile shear and impact strength tests showed that 1% of dendritic polyester polyol (the molar percentage of isocyanate) was the optimum content to get cured epoxy with desired tensile shear strength and impact strength. The curing and toughening mechanism was proposed based on the experimental results.

      PubDate: 2017-11-09T08:35:07Z
       
  • Synthesis of nanoparticle-enhanced polyurethane foams and evaluation of
           mechanical characteristics
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Jong-Min Kim, Jeong-Hyeon Kim, Jae-Hyeok Ahn, Jeong-Dae Kim, Sungkyun Park, Kang Hyun Park, Jae-Myung Lee
      Owing to their many advantageous properties, polyurethane-based insulating materials are suitable for liquefied natural gas carrier (LNGC) cargo containment systems (CCSs). Because an LNGC CCS, which has a 110 K operating temperature, is exposed to continuous sloshing impact loads from ocean waves, the insulating and mechanical capabilities should be simultaneously secured. However, cracking and failure problems have been consistently reported in shipyards owing to the performance limitations of current insulating materials. Therefore, for the present study, nanoparticle-enhanced polyurethane foams (PUFs) with various contents of graphene oxide (GO) and graphite were synthesized to resolve such industrial problems. A wt%-dependent SEM analysis was then carried out to understand the effects of nanoparticles on the cell morphologies of the developed materials. The mechanical properties were investigated at both ambient and boiling temperatures of LNG (110 K). In addition, the thermal conductivity of nanoparticle-enhanced PUF was evaluated. Finally, the macroscopic failure characteristics were also determined. The results indicate that the microstructure and mechanical strength are enhanced compared with neat PUFs, with a significant dependence on the weight percent of the nanoparticles.

      PubDate: 2017-11-09T08:35:07Z
       
  • Sensitivity to material contrast in homogenization of random particle
           composites as micropolar continua
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Emanuele Reccia, Maria Laura De Bellis, Patrizia Trovalusci, Renato Masiani
      Several composite materials used in engineering – such as ceramic/metal matrix composites, concrete, masonry-like/geo–materials and innovative meta–materials – have internal micro-structures characterized by a random distribution of inclusions (particles) embedded in a matrix. Their structural response is highly influenced not only by the mechanical properties of components, but also by the shape, size and position of the inclusions. In this work, we adopt a statistically-based micropolar homogenization procedure, to obtain the overall elastic properties of homogeneous micropolar continua able to naturally account for scale and skew–symmetric shear effects. Attention is paid to the sensitivity to material contrast, defined as the mismatch between classical and micropolar constitutive properties of matrix and inclusions. A statistical specifically conceived convergence criterion is adopted which allow us to identify the REV (Representative Volume Element) for any value of material contrast.

      PubDate: 2017-11-09T08:35:07Z
       
  • Thermally conductive polymeric composites incorporating 3D MWCNT/PEDOT:PSS
           scaffolds
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Cai-Wan Chang-Jian, Er-Chieh Cho, Kuen-Chan Lee, Jen-Hsien Huang, Po-Yu Chen, Bo-Cheng Ho, Yu-Sheng Hsiao
      Although several types of stabilizers have been investigated recently to disperse carbon nanotubes (CNTs), the most common of them are thermal insulators that increase the thermal resistance and hinder the heat conduction across the CNT junctions. In this study, we dispersed multi-wall carbon nanotubes (MWCNTs) using the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a functional surfactant. Upon sonication, PEDOT:PSS covered the surfaces of the MWCNTs, thereby preventing their π-stacking and increasing their dispersion. Moreover, PEDOT:PSS acted as a thermally conductive bridge that connected the MWCNTs and decreased their thermal resistance. We employed a freeze-drying method to prepare MWCNT/PEDOT:PSS composites with hierarchical microstructures. After introducing polydimethylsiloxane (PDMS) into the MWCNT/PEDOT:PSS foam, the thermal conductivity of the MWCNT/PEDOT:PSS and PDMS composite reached 1.16 W/mK—over 550% higher than that of pure PDMS. These results suggest that such PDMS composites might be useful as thermal interface materials for thermal management in electronic and photonic applications.

      PubDate: 2017-11-09T08:35:07Z
       
  • Acoustic emission for interlaminar toughness testing of CFRP: Evaluation
           of the crack growth due to burst analysis
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Fabian Lissek, Andreas Haeger, Volker Knoblauch, Sergej Hloch, Frank Pude, Michael Kaufeld
      The paper deals with interlaminar fracture toughness testing of three different types of specimens from unidirectional aerospace laminate M21/T800S (autoclaved and hot pressed) and the woven fabric ECG Carbon 12k with respect to the ASTM Standard D5582. Simultaneously the materials were monitored by acoustic emission to evaluate the results via burst analysis. CFRP-specimens were mounted in a CNC-machining center by a chopper wire. The lower wire was fixed at a load cell (KISTLER 9257 B) to measure the force development. Standard specification the movement speed in z-direction was set to 5 mm/min. The acoustic emission sensor iMPact XS with accuracy is ±5% with a reference sensitivity of >1200 pC/N was fixed on the DCB-specimens with a two-sided adhesive tape with thickness of 0,5 mm. The sensor iMPact XS has a frequency range from 1 mHz up to 1 MHz limited to a maximum of 500 kHz. It has been found that the material properties correlate well with the results of the acoustic emission analysis. The burst rate reflects the manufacturing processes as it is influenced directly by the fibre bridging which occurs particularly for autoclaved composites. In contrast, the burst energy is not affected by the manufacturing process. It is only depending from the matrix properties.

      PubDate: 2017-11-09T08:35:07Z
       
  • Multi-layer graphene reinforced aluminum – Manufacturing of high
           strength composite by friction stir alloying
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Saurabh Dixit, Avik Mahata, D. Roy Mahapatra, Satish V. Kailas, K. Chattopadhyay
      The paper reports manufacturing of a multi-layer graphene embedded composite of aluminium alloys by direct exfoliation of graphite into graphene with the help of Friction Stir Alloying (FSA). The formation of this nano-composite and optimization of the process parameters led to an approximately two-fold increase in the strength, without loss in ductility, due to the dispersion of the graphene in aluminium. The manufacturing process is scalable and cost effective as it uses graphite powder and aluminium sheets as the raw materials. The presence of graphene layers in the metal matrix was confirmed using Raman spectroscopy as well as TEM. The graphene sheet thickness was measured using AFM after extracting it from the composite. Molecular dynamic simulation results reveal the evolution of newer structures and defects that have resulted in the enhanced properties of the nano-composite. These findings open up newer possibilities toward efficient and scalable manufacturing of high-strength high-ductility metal matrix based graphene nano-composites.
      Graphical abstract image

      PubDate: 2017-11-09T08:35:07Z
       
  • Numerical evaluation of the influence of porosity on bending properties of
           2D carbon/carbon composites
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Xujiang Chao, Lehua Qi, Wenlong Tian, Xianghui Hou, WenJing Ma, Hejun Li
      Numerical simulation with progressive damage criterion is implemented to investigate the effect of porosity on the bending properties of 2D cross-ply carbon/carbon (C/C) composites. The mechanical properties of Pyrocarbon matrix regarding the change of porosity are calculated by using Mori-Tanaka approach. Combining with the stiffness degradation scheme, the ultimate bending strengths are calculated in Abaqus though a user-defined subroutine (USDFLD). Delamination is modelled by inserting cohesive elements between two adjacent plies. A good agreement is obtained when the FEM results are compared to three-point bending experiments. The FEM results show that the bending strength decreases greatly with the increase of porosity. When the porosity reaches up to 18%, the bending strength is decreased by 57%. The major fracture behaviors are interlamination delamination and continuous crack damage in 90° plies. With the increase of porosity, more severe interlamination delamination will be slightly aggravated. In addition, the increase of porosity will also accelerate the damage in 90° plies.

      PubDate: 2017-11-09T08:35:07Z
       
  • Nonlinear elastic properties of graphene sheet using MM3 potential under
           finite deformation
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Sandeep Singh, B.P. Patel
      MM3 interatomic potential is combined with Cauchy–Born rule for the first time to predict elastic properties of the graphene sheets at infinitesimal and finite strains. Further, using plane stress condition, basal plane stiffness and Poisson's ratio calculated using MM3 potential are found to be 310.59 nN/nm and 0.28, respectively. The elastic properties calculated using MM3 potential are somewhat better as compared to those of predicted through Tersoff–Brenner and second generation REBO potentials when compared with the experimental results. Elastic properties are also obtained with MM3 potential considering alternative empirical constants for bond stretch energy term. The present results are also compared with those obtained through modified Morse and first/second generation REBO potentials. The present multiscale model in the framework of MM3 potential will also facilitate the further investigations on the large atomistic structures with greater accuracy.

      PubDate: 2017-11-09T08:35:07Z
       
  • Synthesis of
           poly(vinylidenefluoride-trifluoroethylene)-0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3-reduced
           graphene oxide-composite sheet and its application to flexible energy
           harvesting
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Usman Yaqoob, A.S.M. Iftekhar Uddin, Gwiy-Sang Chung
      Here the synthesis and the optimization of piezoelectric materials by varying the reduced graphene oxide (RGO) contents in the poly(vinylidenefluoride-trifluoroethylene)-0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3(P(VDF-TrFE)-PMN-PT) composite and their application to low-pressure and low-frequency energy harvesting have been reported. Among the synthesized piezoelectric compositions, the PPMR5 (P(VDF-TrFE)-PMN-PT-RGO (RGO = 0.5%)) sample exhibits a maximum dielectric constant of 60 and a relatively high dielectric loss of 0.0654 at 1 kHz. Additionally, flexible piezoelectric energy harvester (FPEH) made off PPMR5 sheet reveals highest output performance under mechanical deformation. The fabricated FPEH demonstrate a maximum open-circuit output voltage of 8 V(pk-pk) and a short-circuit current of 3.5 μA(pk-pk) at an external applied force of 2N. Furthermore, the FPEH exhibits an output power density of 6.5 μW/cm2 at 1 MΩ load resistance. The fabricated device was also exposed to several pressing-releasing cycles to confirm its stability. The device shows excellent stability even after 1000 pressing-releasing cycles. Finally, our fabricated FPEH can be a promising energy source for futuristic flexible electronics.
      Graphical abstract image

      PubDate: 2017-11-09T08:35:07Z
       
  • Experimental and numerical studies on the impact response of
           damage-tolerant hybrid unidirectional/woven carbon-fibre reinforced
           composite laminates
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Haibao Liu, Brian G. Falzon, Wei Tan
      A woven five-harness satin (5HS) weave with AS4 carbon fibres, and unidirectional high strength IMS60 carbon fibres were used to manufacture hybrid laminates, using resin infusion, to assess their performance in low velocity impact tests. Load/energy-time curves and load-displacement curves were extracted from the experimental data, and non-destructive C-scanning was performed on all pre- and post-impacted specimens to quantify the extent of damage incurred. A finite element-based computational damage model was developed to predict the material response of these hybrid unidirectional/woven laminates. The intralaminar damage model formulation, by necessity, consists of two sub-models, a unidirectional constitutive model and a woven constitutive model. The built-in surface-based cohesive behaviour in Abaqus/Explicit was used to define the interlaminar damage model for capturing delamination. The reliability of this model was validated using in-house experimental data obtained from standard drop-weight impact tests. The simulated reaction-force and absorbed energy showed excellent agreement with experiment results. The post-impact delamination and permanent indentation deformation were also accurately captured. The accuracy of the damage model facilitated a quantitative comparison between the performance of a hybrid unidirectional/woven (U/W) laminates and a pure unidirectional (PU) carbon-fibre reinforced composite laminates of equivalent lay-up. The hybrid laminates were shown to yield better impact resistance.

      PubDate: 2017-11-09T08:35:07Z
       
  • Snubbing effect in atomic scale friction of graphene
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Shu Jian Chen, Xu Pei Yao, Quan Wang, Wen Hui Duan
      Knowledge of the snubbing effect in atomic scale friction is essential for understanding the interaction between graphene and contacted materials in graphene composites, coatings, and nanodevices. However, current understanding of this snubbing effect is very limited. In the present study, non-equilibrium molecular dynamics is used to quantify the atomic scale snubbing friction on graphene surfaces and the effects of incline angle, tension, and surface properties. The results show evidence of a snubbing friction force that is found to range from one thousandth to one tenth of the tension in graphene. Snubbing friction behavior is found to be exponential to the inclined angle and the friction coefficient and proportional to the tension in graphene. Results shows that changes in lattice orientation and surface decoration cause variation of the friction coefficient by 5 orders of magnitude, from 0.06 to 42 × 10−3, as a result of changes in the collision angle between atoms at the interface.

      PubDate: 2017-11-09T08:35:07Z
       
  • Mechanical properties of EPS filled syntactic foams prepared by VARTM
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Qiyong Yu, Yan Zhao, Anqi Dong, Ye Li
      In this study, syntactic foams with honeycomb like structure were prepared with hollow glass microspheres (HGMs), epoxy resin, and expanded polystyrene (EPS) beads. A novel manufacturing approach of Vacuum Assisted Resin Transfer Mould (VARTM) was designed to avoid the effect of buoyancy on the EPS beads, due to the different densities of the raw materials. The EPS beads were served as sacrificial templates and shrank at high temperature, and thus produced hollow structure. EPS beads with four types of size were used. The average diameters are 0.75 mm, 1.50 mm, 2.50 mm and 4.00 mm, respectively. The foam density of the obtained syntactic foam can vary from 0.24 g/cm3 to 0.28 g/cm3. It was demonstrated by scanning electron microscope (SEM) that the EPS beads and HGMs could be dispersed uniformly in the resin system. Test results indicated that the resin permeating time, compressive strength, and syntactic foam densities presented an increasing tendency as the decrease of the EPS beads' diameters. Correspondingly, the average compressive strength enhanced from 3.6 MPa to 9.3 MPa. The resin permeating time increased from 6 min to 27 min with a thickness of 100 mm. In summary, this work provides an optimized way for the preparation of the low-density syntactic foams.

      PubDate: 2017-11-09T08:35:07Z
       
  • 3D ferromagnetic graphene nanocomposites with ZnO nanorods and Fe3O4
           nanoparticles co-decorated for efficient electromagnetic wave absorption
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Na Zhang, Ying Huang, Mingyue Wang
      The nanocomposites of combining magnetic nanoparticles with dielectric materials are highly desirable for high performance electromagnetic (EM) wave absorbers due to their great impedance matching property. In this work, 3D ferromagnetic graphene nanocomposites with ZnO nanorods and Fe3O4 nanoparticles co-decorated have been successfully synthesized via a facile solvothermal process in combination with the co-precipitation route, and the EM wave absorption performance is first reported. The maximum reflection loss (RL) of the 3D RGO/Fe3O4/ZnO nanocomposites reaches −57.0 dB at 13.5 GHz with a matching thickness of only 2.0 mm. The effective absorption bandwidth with the RL less than −10 dB can be tuned to 10.8 GHz (5.9–16.7 GHz) at the absorber thickness of 1.5–4.0 mm, which covers the whole X band. These results suggest that the 3D nanocomposites possess the advantages of thin thickness, broad bandwidth, lightweight and strong absorption, and can be used as promising materials for stealth camouflage techniques.
      Graphical abstract image

      PubDate: 2017-11-09T08:35:07Z
       
  • A study on the effect of electron acceptor-donor interactions on the
           mechanical and interfacial properties of carbon black/natural rubber
           composites
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Jong Hyuk Cha, Gi-Joo Shin, Min-Joo Kang, Hyo In Lee, Kyong Yop Rhee, Soo-Jin Park
      In order to fabricate carbon black/NR composites, various types of carbon black were added as fillers to a natural rubber (NR) matrix. The influence of the types of carbon black on the resulting composite was investigated by measuring its mechanical properties. In addition, to determine the relationship between the filler and the matrix, the adsorption and surface properties of the carbon black samples were examined using X-ray diffraction and Brunauer–Emmett–Teller isotherms. Mechanical properties of the carbon black/NR composites such as tensile strength and tearing energy were determined. The results showed that the mechanical properties of the carbon black/NR composites were considerably improved, owing to the increase in the London dispersive component of the carbon black surface free energy.

      PubDate: 2017-11-09T08:35:07Z
       
  • Electrically conductive green composites based on epoxidized linseed oil
           and polyaniline: An insight into electrical, thermal and mechanical
           properties
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Vinay Khandelwal, Sushanta K. Sahoo, Ashok Kumar, Gaurav Manik
      Renewable resource based electrically conductive composites were prepared using polyaniline (PANI) as a conductive filler and epoxidized linseed oil (ELO) as the matrix. Linseed oil (LO) was epoxidized to form ELO and characterized through 1H NMR and IR spectra. Bio-based ELO/PANI conducting composites were prepared by varying the PANI concentration with an aim of attaining the electrical conductivity in the antistatic range (10−8 to 10−3 S/cm) to replace its petro-based counterpart. Conductivity increased with PANI upto the order of 10−6 S/cm with percolation threshold at around 7% of PANI. The shear stress and viscosity of the uncured ELO resin and ELO/PANI resin mixture were studied as a function of shear rate. Differential scanning calorimetry (DSC) studies showed that addition of PANI had a minimal effect on ELO curing at all concentrations. Dynamic mechanical analysis indicated that PANI as a filler provided mechanical fortification in the rubbery region and increased glass transition temperature (T g) significantly. Thermal stability of ELO remained almost unaffected with the PANI incorporation. Microscopic observation revealed good distribution of PANI in ELO matrix even at higher loading. Interestingly, tensile strength and Young's modulus increased by ∼8 and ∼27 folds, respectively, at 15% PANI content.

      PubDate: 2017-11-09T08:35:07Z
       
  • Two failure modes of C/SiC composite under different impact loads
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Yang Yang, Fei Xu, Xiangyang Gao, Gangwei Liu, Meng Zhang
      C/SiC composites have wide applications in thermal protective structures of spacecraft, whose impact resistance is essential for safe service. As a continuation of the previous experimental work, two failure modes of C/SiC composites under the impact loads of different shapes of projectiles are investigated through numerical simulations. First, based on the analysis of the damage mechanism, a two-part brittle orthotropic constitutive model is proposed by coupling the orthotropic elastic relationship and the equation of state to describe the dynamic impact response of C/SiC to the spherical projectile. Second, owing to a distinctive equivalent hardening failure mode of C/SiC when impacted by the flat flyer, a modified three-part orthotropic constitutive model is proposed, which introduces an additional pseudoplastic sub-model to describe the yield and post-yield responses. Finally, compared with the experimental results, the rationality and accuracy of these two models and their corresponding parameters are illustrated with respect to damage characteristics, stress-strain curves, the shape of the debris cloud, and free surface velocity, using the commercial software Autodyn.

      PubDate: 2017-11-09T08:35:07Z
       
  • Effects of wool fibre and other additives on the flammability and
           mechanical performance of polypropylene/kenaf composites
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Aruna Subasinghe, Arcot A. Somashekar, Debes Bhattacharyya
      Influence of wool fibres (WF) in improving the flame retardant and mechanical properties of polypropylene/kenaf fibre/intumescent ammonium polyphosphate (PP/KF/APP) composites is described. Flammability of PP/KF/APP/WF composite was evaluated using cone calorimetry, UL 94-V vertical burning tests and thermo-gravimetric analysis, and compared to results of similar composites which contained an ultraviolet ray stabiliser and colourant combination (PP/KF/APP/UVC). Tensile, bending and impact test analyses were also conducted on both sets of composites. PP/KF/APP/WF system had stable residual char at elevated temperatures, significantly improving fire protection. High degree of cross-linked stable char formation and residual char in PP/KF/APP/WF composite provided sufficient evidence of synergistic effect of wool. WF increased the tensile modulus of the composite by approximately 16%, while UVC (together with APP) improved the composite's flexural stiffness by 21%.

      PubDate: 2017-11-09T08:35:07Z
       
  • Nonlinear vibration of functionally graded graphene-reinforced composite
           laminated cylindrical panels resting on elastic foundations in thermal
           environments
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Hui-Shen Shen, Y. Xiang, Yin Fan, D. Hui
      This paper studies the small and large amplitude vibration behaviors of graphene-reinforced composite (GRC) laminated cylindrical panels supported by an elastic foundation under thermal environmental conditions. The temperature dependent material properties of GRC are assumed to be functionally graded in a piece-wise pattern by changing the volume fraction of graphene in the panel thickness direction and are estimated by the extended Halpin-Tsai micromechanical model. The motion equations for the nonlinear vibration problem of the panels are obtained from the higher order shear deformation shell theory and take into consideration of the effects of the von Kármán geometric nonlinearity, the elastic foundation and the temperature change. The nonlinear vibration solutions for the FG-GRC laminated cylindrical panels can be obtained by applying a two-step perturbation technique. We observe that the natural frequencies of FG-GRC panel with symmetrical distribution of graphene reinforcements are higher, whereas the nonlinear to linear frequency ratios of the same panel are lower than those of panels with uniform or unsymmetrical distribution of graphene reinforcements.

      PubDate: 2017-11-09T08:35:07Z
       
  • Rate-dependent tensile failure behavior of short fiber reinforced PEEK
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Chunyang Chen, Chao Zhang, Chenlin Liu, Yinggang Miao, Shing-Chung Wong, Yulong Li
      Polyetheretherketone (PEEK) and two types of short-fiber (carbon fiber and glass fiber) reinforced PEEK were investigated under uniaxial tensile tests of various strain rates. The strain rate varies in the range between 10−3 and 103 s−1. The paper aims to show the rate dependency of mechanical properties of short-fiber reinforced PEEK, and the relationship between its failure behavior with strain rate and fiber type. High-speed camera system and digital image correlation technique were employed to measure the evolution of strain distributions. Scanning electron microscopy (SEM) was introduced to examine and analyze the failure mechanisms. The results indicated that the ultimate stresses of PEEK and PEEK composites presented little sensitivity against strain rates, while the failure strain of pure PEEK decreased and the failure strain of PEEK composites increased apparently with the increase of strain rate. Also, carbon fiber reinforced and glass fiber reinforced specimens showed differences in sensitivity to strain rate and failure mechanisms, the latter of which is further confirmed by in-situ SEM tensile tests.

      PubDate: 2017-11-09T08:35:07Z
       
  • Magnetic field-induced enhancement of thermal conductivities in polymer
           composites by linear clustering of spherical particles
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Jae-Yong Chung, Jung-Goo Lee, Youn-Kyung Baek, Pyung-Woo Shin, Young-Kuk Kim
      We developed linearly linked spherical fillers in polymer composites with incorporating Al2O3-Fe3O4 hybrid particles under a magnetic field to form thermal networks for high thermal conductivity. The Al2O3-Fe3O4 hybrid particles were prepared by a simple precipitation method and their magnetic properties were characterized with magnetic hysteresis. The Al2O3-Fe3O4 hybrid particles were well aligned through direction of magnetic field as confirmed by microscopic observation. The polymer composites obtained with Al2O3-Fe3O4 hybrid particles possessed high thermal conductivity in a parallel magnetic alignment direction at low filler loading, which is more than 240% outperformed the composites with randomly dispersed fillers.
      Graphical abstract image

      PubDate: 2017-11-09T08:35:07Z
       
  • Properties of natural fibre composites for structural engineering
           applications
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Kin-tak Lau, Pui-yan Hung, Min-Hao Zhu, David Hui
      Since the last two decades, many researchers have refocused on using natural fibres, as reinforcements for cementitious and polymer based structural materials. The use of natural fibres for structural applications is not modern. Long before a century ago people in many small towns in China and Korea already mixed straws with mud to build walls in villages. However, at that time there was no systematic way to study the fundamental mechanism and interpret how natural fibres strengthen structures and what processes should be adopted to maximize the performance of natural materials. Currently, nevertheless natural fibre reinforced polymer (NFRP) composites have been widely used in automotive and building industries, it is still a room to promote them to high-level structural applications like primary structural components of aerospace and maritime structures. It is difficult to evaluate the quality of natural fibres, which generally extracted from the nature, and thus it is challenging to develop a generic formula to predict the structural and mechanical properties of NFRP composites. Hydrophilic and hydrophobic properties of natural fibres and polymers, respectively, cause poor bonding interaction at interface. Traditional shear-lag model was popularly used to study the stress transfer mechanism between fibre and matrix of advanced composites. However, such model is not applicable to NFRP composites due to the imperfect shape of nature fibres along their longitudinal direction and irregular shape of fibres' cross section. In this paper, analysis on different aspects in related to the use of natural fibres for real life engineering applications is given. Basic analytical models focusing on the stress transferability in composites are also discussed to provide an insight for researchers and engineers to understand the design and requirements of using natural fibres for structural applications in the future.

      PubDate: 2017-11-09T08:35:07Z
       
  • Thermoelectric transport in ultrathin poly(3,4-ethylenedioxythiophene)
           nanowire assembly
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Jing Zhang, Kun Zhang, Fujun Xu, Shiren Wang, Yiping Qiu
      With the highly ordered structure and thus probably fast carrier transport, one-dimensional (1D) conducting polymers are very promising as organic thermoelectric (TE) materials. Many efforts have been made toward the elucidation of TE transport in polymer nanowires assembly; however, the mechanism for the improvement in thermoelectric property is still far from clear. Here, we systematically investigate the TE transport in 12-nanometer-wide poly(3,4-ethylenedioxythiophene) nanowires (PEDOT NWs) assembly. The iron (III) chloride oxidized PEDOT NWs shows high electrical conductivity σ (∼540 S/cm), an enhanced Seebeck coefficient S that is 2.6 times of that of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and tuned power factor (PF∼35.8 μW/m·K2). To the best of our knowledge, it outperforms the TE performance of all reported 1D conducing polymers based films. More importantly, we carefully interpret the origin of σ and S enhancements in PEDOT NWs-based films. The high σ mainly results from the significant increment of carrier mobility μ, which is mainly due to preferred edge-on orientation and high crystallinity of PEDOT chains. The large S in PEDOT NWs-based films stem from the sharp feature of the density of states at Fermi level.

      PubDate: 2017-11-09T08:35:07Z
       
  • A review of extending performance of epoxy resins using carbon
           nanomaterials
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Shan Liu, Venkata S. Chevali, Zhiguang Xu, David Hui, Hao Wang
      Carbon nanomaterials are receiving worldwide attention because of their multi-faceted superiority in thermal conductivity, flame retardancy, mechanical stability, electrical conductivity, and biocompatibility. In this review, a survey of the literature on extending performance of epoxy resins based on carbon nanomaterials is presented. The structure-performance relationships for different carbon nanomaterials modified epoxy are closely analyzed. The performance extension in mechanical, electrical, thermal conductivity, flame retardancy, antidegradation, and tribological properties of epoxy are reviewed in detail. Other application areas including biocompatibility, biodegradability, gas barrier properties, shape memory, and electromagnetic interference shielding are touched. The challenges and opportunities in carbon nanomaterials functionalized epoxy composites are also discussed.

      PubDate: 2017-11-09T08:35:07Z
       
  • Structural behavior of GFRP reinforced concrete columns under the
           influence of chloride at casting and service stages
    • Abstract: Publication date: 1 March 2018
      Source:Composites Part B: Engineering, Volume 136
      Author(s): Ao Zhou, Cheuk Lun Chow, Denvid Lau
      Corrosion attack due to chloride ions is a major problem found in steel reinforced concrete structures when subjected to marine environment. Glass fiber reinforced polymer (GFRP) has become an alternative reinforcement in marine concrete structures due to its excellent corrosion resistance, making it possible to combine with concrete composed of seawater and sea sand. However, the knowledge on the short-term and long-term properties of GFRP reinforced concrete columns is still limited. In order to facilitate the practical application of GFRP reinforced concrete in marine environment, the effect of chloride ions on the structural behaviors of GFRP reinforced concrete columns is investigated here. Numerous specimens consisting of GFRP reinforced concrete columns and steel reinforced concrete columns with different chloride concentrations were fabricated, conditioned and tested. The test results show that GFRP reinforced concrete columns cast with saturated water suffer a deterioration of 27.9% in load carrying capacity, but possess an enhancement of 104% in ductility when compared to those of specimens cast with distilled water. Meanwhile, it is observed that the GFRP reinforced concrete column possess a ductile failure mode, which indicates that the GFRP spirals can provide an effective confinement to the concrete core even in high chloride environment for a prolonged time. Such findings provide solid evidence to the feasibility and application of GFRP reinforced concrete in the offshore structures or artificial islands with great environmental and economic benefits.
      Graphical abstract image

      PubDate: 2017-10-26T15:30:28Z
       
  • The preparation of Ni/GO composite foils and the enhancement effects of GO
           in mechanical properties
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): You Li, Guofeng Wang, Siyu Liu, Shanshan Zhao, Kaifeng Zhang
      Graphene oxide (GO) was prepared by an improved Hummers method, and nanocrystalline (NC) Ni and Ni/GO foils were prepared by pulsed electrodeposition. This paper mainly investigated the effects of GO in Ni/GO composites. The surface of the prepared GO has many oxygen-containing functional groups and a high aspect ratio. The addition of GO in Ni/GO foils not only effectively lowers the matrix grain size but also contributes to the growth of Ni toward the (111) direction. Furthermore GO covers the surface of the matrix grains and passes through the grain boundary. Compared to NC Ni, the mechanical properties, such as hardness, elastic modulus, elongation and fracture strength showed significant improvements for the Ni/GO composite foil. The use of GO can effectively inhibit the growth of matrix grain boundaries at high temperatures.
      Graphical abstract image

      PubDate: 2017-10-18T15:04:13Z
       
  • A progressive intraply material deterioration and delamination based
           failure model for the crashworthiness of fabric composite corrugated beam:
           Parameter sensitivity analysis
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Yiru Ren, Hongyong Jiang, Binhua Gao, Jinwu Xiang
      A high-accuracy progressive failure model based on continuum damage mechanics (CDM) is proposed to simulate the quasi-static axial crushing of composite corrugated beam. To predict various physical phenomena, both of the intra-ply damage and inter-ply interface damage are considered. The damages of intra-ply fiber and matrix are initiated with stress failure criteria and progressive damage propagation is modeled with a stiffness discount method and energy criteria. The deformation gradient algorithm is effectively used for the erosion of failure elements. Further, the delamination damage is predicted by a triangle traction-separation model with a mix-mode fracture energy criterion. To obtain insights into complicated failure mechanisms, a parameter sensitivity study is carried out to study effects of numerical parameters on failure responses, including element erosions, failure strengths, elasticity modulus, friction properties, etc. Results show that the established model correlates well with experiment on failure modes, impact loads and energy-absorbing characteristics. It is found that element erosion parameters are the most influential parameters for impact loads. The fiber compression strength and friction coefficients exhibit dramatic effect on energy-absorbing capability and failure modes of specimen.

      PubDate: 2017-10-18T15:04:13Z
       
  • Postbuckling of sandwich plates with graphene-reinforced composite face
           sheets in thermal environments
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Yin Yu, Hui-Shen Shen, Hai Wang, D. Hui
      Present investigation deals with the buckling and postbuckling behavior of a sandwich plate with a homogeneous core and graphene-reinforced composite (GRC) face sheets resting on an elastic foundation in thermal environments. The material properties of GRC face sheets are assumed to be piece-wise functionally graded by changing the volume fraction of graphene in the thickness direction. The material properties of both the homogeneous core layer and the GRC face sheets are assumed to be temperature-dependent, and are estimated by the extended Halpin-Tsai micromechanical model. The higher order shear deformation plate theory and the von Kármán-type kinematic nonlinearity are used to derive the governing equations which account for the plate-foundation interaction and the thermal effects. The buckling loads and the postbuckling equilibrium paths are obtained by using a two-step perturbation technique. The impacts of the distribution type of reinforcements, core-to-face sheet thickness ratio, plate aspect ratio, temperature variation, foundation stiffness and in-plane boundary conditions on the postbuckling behavior of sandwich plates with functionally graded GRC face sheets are studied in detail.

      PubDate: 2017-10-18T15:04:13Z
       
  • A novel material degradation model for unidirectional CFRP composites
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Libin Zhao, Yang Li, Jianyu Zhang, Longwei Zhou, Ning Hu
      A novel material degradation model (MDM), which is an essential component of progressive damage models for failure analysis of composite structures, is proposed based on the representative volume element (RVE) method. In this model, a material degradation rule accounting for seven failure modes in a modified Hashin-type failure criterion is proposed. This rule determines the mechanical parameters that are degraded when a failure occurs. The degradation factors of these parameters are calculated from the RVE models for perfect and damaged materials corresponding to the seven failure modes, which are based on the fundamental properties of transverse isotropic fibers and isotropic matrix. To verify the proposed method, the calculated MDMs are used in the progressive failure analyses of open-hole laminates made of three types of CFRP composites under tensile and compressive loadings. Furthermore, the failure analyses of four kinds of double-lap single-bolted joint structures with various layups and geometry dimensions are also conducted under tensile loading. The numerical predictions of failure loads, failure patterns and load-displacement curves are compared to the experimental results. Good agreement between the model predictions and the experimental results demonstrates the effectiveness of the proposed MDM for the progressive damage analyses of open-hole laminates and composite bolted joints.

      PubDate: 2017-10-18T15:04:13Z
       
  • Buckling optimization of laminated truncated conical shells subjected to
           external hydrostatic compression
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Hsuan-Teh Hu, Hsien-Chih Chen
      Buckling analyses of laminated truncated conical shells subjected to external hydrostatic compression are carried out by employing the Abaqus finite element program. The critical buckling loads of these truncated conical shells with a given material system are maximized with respect to fiber orientations by using the golden section method. Through parametric studies, the influences of the end condition, shell thickness, shell length, shell radius ratio and cutout size on the optimal buckling loads, the associated optimal fiber orientations and the associated buckling modes are demonstrated and discussed.

      PubDate: 2017-10-18T15:04:13Z
       
  • Sustainable composite fused deposition modelling filament using recycled
           pre-consumer polypropylene
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): David Stoof, Kim Pickering
      Composite filaments with differing harakeke, hemp fibre or recycled gypsum contents (0-50 wt%) in pre-consumer recycled polypropylene (PP) were produced and mechanically assessed. Furthermore, a novel method of measuring shrinkage in 3D printed components was also developed and used to assess shrinkage of filaments. The most successful filaments contained 30 wt% harakeke fibre and had a tensile strength and Young's modulus of 39 MPa and 2.8 GPa respectively, providing improvements in tensile strength and Young's modulus compared to those of plain PP filament of 74% and 214% respectively. However, these properties were seen to reduce on printing, although fibre reinforcement was still observed to provide benefit in terms of strength and shrinkage. The cause of the mechanical property reduction was assumed to be stress relaxation of the polymer during printing which is conducted at lower pressure compared to filament production. 30 wt% harakeke filament also underwent the least shrinkage of 0.34% corresponding to a net reduction of 84% relative to plain PP.

      PubDate: 2017-10-18T15:04:13Z
       
  • Microwave absorption properties of holey graphene/silicone rubber
           composites
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Chun-Yu Chen, Nen-Wen Pu, Yih-Ming Liu, Li-Hang Chen, Chia-Hung Wu, Tsai-Yi Cheng, Ming-Hsien Lin, Ming-Der Ger, Yann-Jang Gong, You-Yu Peng, Peter M. Grubb, Ray T. Chen
      The complex permittivity and return loss (RL) for the composites of silicone rubber filled with holey graphene nanosheets (HGNS, prepared by ultra-rapid heating during the step of thermal reduction/exfoliation of graphite oxide) were measured in the 3–18 GHz range. HGNS-based composites were found to have significantly higher microwave absorption than composites incorporating other types of graphene reduced at lower heating rates. Even with only 1 wt.% loading, its experimentally measured RL reached −32.1 dB at 13.2 GHz with a thickness of 2 mm, and simulation suggested that at a thickness of 3 mm its RL can be as low as −45.3 dB at 7.8 GHz. Material characterization indicated that the density of the holes increased with the temperature ramp rate, and the hole sizes ranged from 5 to 300 nm. Compared to other graphene samples, HGNS possessed significantly larger specific surface area and higher density of defects, suggesting that defect-induced losses, interfacial polarization, and multiple reflection/scattering at the interfaces are the major loss mechanisms. Our simple and low-cost process as well as the very low loading ratio of HGNS are advantageous for cost reduction in future applications.
      Graphical abstract image

      PubDate: 2017-10-18T15:04:13Z
       
  • Modeling and classification of defects in CFRP laminates by thermal
           non-destructive testing
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): R. Marani, D. Palumbo, V. Renò, U. Galietti, E. Stella, T. D'Orazio
      Pulsed thermography has been used for many years to investigate the presence of subsurface defects in composite materials for aeronautics. Several methods have been proposed but only few of them include a complete automated approach for the effective defect characterization. This paper presents a novel method which approximates the thermal decays on the laminate surface, induced by a short heat pulse, by means of an exponential model in three unknowns (model parameters), estimated in the least squares sense. These parameters are discriminant and noise-insensitive features used to feed several classifiers, which are trained to label possible defects according to their depths. Experimental tests have been performed on a carbon-fiber reinforced polymer (CFRP) laminate having four inclusions of known properties. The comparative analysis of the proposed classifiers has demonstrated that the best results are achieved by a decision forest made of 30 trees. In this case the mean values of standard and balanced accuracies reach 99.47% and 86.9%, whereas precision and recall are 89.87% and 73.67%, respectively.

      PubDate: 2017-10-18T15:04:13Z
       
  • Inherent seismic resilience of RC columns externally confined with
           nonbonded composite ropes
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Theodoros C. Rousakis
      This paper highlights the inherent seismic resilience of reinforced concrete (RC) columns externally confined with nonbonded composite ropes. It critically reviews the inherent seismic resilience reserve of such columns at material, at section and at member level. The study further elaborates recent experimental evidence to reveal the structural resilience of the retrofit technique (excluding risk-based assessment). It focuses on the damage build-up and control at member level that may prevent the collapse of critical infrastructure. A new generalized design concept is concluded towards enhanced inherent resilience of similar members. It applies to members with the weakest link (in this case also being the main bearing material, the concrete core) suffering a local damage, susceptible to further build-up. This damage localization disrupts uniformity and homogeneity in response. The design approach suggests that adequate confining action with continuous elastic flexible rope (or tape) may preserve damage-sensitive-restriction in a way that globalizes damage. It may succeed damage redistribution inside the core throughout loading and make the core again more uniform and more homogeneous in response, thus maximizing energy dissipation.

      PubDate: 2017-10-18T15:04:13Z
       
  • A technical review on epoxy-clay nanocomposites: Structure, properties,
           and their applications in fiber reinforced composites
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Omid Zabihi, Mojtaba Ahmadi, Saeid Nikafshar, Karthik Chandrakumar Preyeswary, Minoo Naebe
      The review presents a survey of the literature on structure–property relationships in epoxy-clay nanocomposites. Herein, various pivotal parameters affecting structures and properties of the nanocomposites including various types of modification as well as a vast range of available dispersion techniques were discussed. Opportunities and challenges in regards to potential applications of nanoclay in multi-scale composites have been also addressed. The multi-scale composites containing nanoclays have been reviewed in terms of mechanical properties in both out-of-plane and in-plane directions, and compared with those containing carbon based nanofillers. In this regards, the improving mechanisms in mechanical properties of both epoxy-clay nanocomposites and nanoclay filled fiber reinforced composites were also discussed.

      PubDate: 2017-10-11T07:32:49Z
       
  • Phase transition and anomalous rheological behaviour of
           polylactide/graphene nanocomposites
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Sima Kashi, Rahul K. Gupta, Thomas Baum, Nhol Kao, Sati N. Bhattacharya
      Polylactide (PLA) nanocomposites with graphene nanoplatelet (GNP) contents of 0–15 wt% were prepared and characterised in terms of rheology and electrical conductivity. As expected for rigid nanofillers, GNP incorporation significantly enhanced the viscoelastic properties of the nanocomposites. Furthermore, above a certain GNP concentration the liquid-like melt flow behaviour changed into a solid-like behaviour. However, this rheological percolation threshold was found to decrease from near 9 wt% at 180 °C to below 6 wt% at 220 °C, detected and measured by Van Gurp-Palmen plots and Winter-Chambon method, respectively. It was also found that the viscoelastic properties of some of the nanocomposites increased with increasing temperature, which is in contrast to the rheology of ideal polymeric melts. The Electrical percolation threshold of the PLA/GNP system, which is determined by a sudden increase in DC conductivity and is indicative of establishment of interconnected conductive structures of GNPs within the matrix, was observed to be between 6 and 9 wt% GNPs. Morphological studies also showed physical contact between the platelets at 9 wt% while at 6 wt% they were still separated by the PLA matrix. These observations challenge the attribution of rheological percolation threshold to the formation of a percolating network of only filler particles within the matrix. A percolating network consisting of both polymer chains and filler particles might be the reason for the temperature dependency of rheological percolation threshold in the PLA/GNP system.
      Graphical abstract image

      PubDate: 2017-10-11T07:32:49Z
       
  • Carbon fiber reinforced silicon carbide composite-based sharp leading
           edges in high enthalpy plasma flows
    • Abstract: Publication date: 15 February 2018
      Source:Composites Part B: Engineering, Volume 135
      Author(s): Lei Luo, Yiguang Wang, Liping Liu, Xing Zhao, Yonghong Lu, Guolin Wang
      Carbon fiber-reinforced silicon carbide (C/SiC) and zirconium diboride-zirconium carbide (ZrB2-ZrC) modified C/SiC (C/SiC-ZrB2-ZrC) sharp leading edges (SLEs) were prepared in this study. Their ablation behaviors were tested in plasma wind tunnels. The results indicated that the ablation of C/SiC SLEs was controlled by the atomic oxidation of SiC, leading to the elimination of SiC. In contrast, C/SiC-ZrB2-ZrC SLEs showed little reduction in plasma flows. During ablation, a ZrO2 skeleton was formed with silica filling inside by the atomic oxidation of SiC. The ZrO2 skeleton suppressed the consumption of SiC, resulting in the improvement of the ablation resistance of C/SiC-ZrB2-ZrC SLEs.

      PubDate: 2017-10-11T07:32:49Z
       
 
 
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