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

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 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)
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Advances in Polymer Science     Hybrid Journal   (Followers: 41)
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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)
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Applied Physics Research     Open Access   (Followers: 3)
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Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
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Archives of Thermodynamics     Open Access   (Followers: 7)
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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)
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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)
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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 Composite Structures
  [SJR: 2.408]   [H-I: 92]   [265 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0263-8223
   Published by Elsevier Homepage  [3048 journals]
  • An approach for stress analysis of corrugated-core integrated thermal
           protection system under thermal and mechanical environment
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Chunlin Gong, Yifan Wang, Liangxian Gu, Shengbo Shi
      The stress distributions in trapezoidal corrugated-core integrated thermal protection system (ITPS) under thermal and mechanical loads are predicted by employing the equivalent sandwich model introduced in our previous study (Gu et al., 2017). The method for prediction of stress based on high-order layerwise theory and the principle of structural mechanics is presented, which considers the effects of temperature-dependent material properties and curvature in sheets. For the top face sheet of ITPS, the local displacement induced by out-of-plane pressure is taken into account in the prediction of stress. And for the bottom face sheet of ITPS, the local displacement induced by corrugated webs is also considered by treating the sheet as beams with proper displacement compatibility. The accuracy of the proposed method is verified by comparison with the results by three-dimensional (3D) finite element analysis. It has been shown that the proposed method requires significantly less computational effort and agrees well with the finite element results.

      PubDate: 2017-11-15T20:10:38Z
  • Nonlocal nonlinear finite element analysis of composite plates using TSDT
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): P. Raghu, A. Rajagopal, J.N. Reddy
      In this work, nonlocal nonlinear finite element analysis of laminated composite plates using Reddy’s third-order shear deformation theory (TSDT) (Reddy, 1984) and Eringen’s nonlocality Eringen and (Edelen, 1972) is presented. The governing equations of third order shear deformation theory with the von Kármán strains are derived employing the Eringen’s (Eringen and Edelen, 1972) stress-gradient constitutive model. The principle of virtual displacement is used to derive the weak forms, and the displacement finite element models are developed using the weak forms. Four-noded rectangular conforming element with 8 degrees of freedom per node has been used. The coefficients of stiffness matrix and tangent stiffness matrix are presented along with nonlocal force vector. The developed finite element model can be employed to capture the small scale deviations from local continuum models caused by material inhomogeneity and the inter atomic and inter molecular forces. Numerical examples are presented to illustrate the effects of nonlocality, anisotropy, and the von Kármán type nonlinearity on the bending behaviour of laminated composite plates.

      PubDate: 2017-11-15T20:10:38Z
  • Investigation of the effect of BaTiO3/CoFe2O4 particle arrangement on the
           static response of magneto-electro-thermo-elastic plates
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): M. Vinyas, S.C. Kattimani
      In this article, a framework based on finite element (FE) methods is proposed for predicting the influence of spatial arrangement of two phase Barium Titanate (BaTiO3) and Cobalt Ferric Oxide (CoFe2O4) particulate composites on the static response of magneto-electro-thermo-elastic (METE) plates. The coupled material properties such as piezoelectric, piezomagnetic, dielectric, magnetic permeability, thermal expansion and pyro co-efficients vary significantly with the spatial arrangement of BaTiO3/CoFe2O4 particulates. The coupled FE governing equations accounting the effect of particle arrangement is presented by incorporating linear coupled constitutive equations of METE composites. Through the condensation technique, the governing equations of METE plates are solved to obtain direct (thermal displacements, electric and magnetic potentials) and derived quantities (stresses, electric displacements and magnetic flux densities). A special attention has been placed on evaluating the pyro-electric and pyro-magnetic coupling effects for different packing arrangement considered namely, Body Centered Cubic (BCC), Face Centered Cubic (FCC) and Simple Cubic (SC) METE particulate composites. Further, parametric studies are carried out to analyse the influence of boundary conditions and aspect ratio. The present study reveals that the multiphysics response of METE plates changes significantly with the packing arrangements of BaTiO3/CoFe2O4 particulates and geometrical parameters. It is believed that the obtained solutions would provide insights into design aspects of METE structures.

      PubDate: 2017-11-15T20:10:38Z
  • Periodic mesh generation and homogenization of inclusion-reinforced
           composites using an element-carving technique with local mesh refinement
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Dongwoo Sohn
      An efficient periodic mesh generation scheme for representative volume elements (RVEs) of inclusion-reinforced composites is proposed with the aid of an element-carving technique. A background mesh with regular hexahedral elements is cut and split to fit periodic configurations of inclusions. The split hexahedral elements around the inclusion-matrix interfaces correspond to polyhedral elements, while the background hexahedral elements remain inside the inclusions and matrices. To further achieve an accurate and efficient RVE modeling, local refinement for the background mesh is introduced near the inclusion-matrix interfaces. Polyhedral elements that have arbitrary numbers of polygonal faces and nodes are also used to connect the refined and original background hexahedral elements. The generated meshes automatically have periodic boundary configurations, and no special treatment is thus required to impose periodic boundary conditions in a computational homogenization. In this paper, the cell-based smoothed finite element method is adopted to reduce the effort involved in explicitly defining shape functions and in accurately conducting numerical integration for polyhedral elements. The effectiveness of the proposed scheme is demonstrated in the numerical examples of generating RVEs, including spherical, ellipsoidal, or cylinder-shaped inclusions. Furthermore, the influences of inclusion configurations on estimating the effective elastic moduli are investigated with the generated meshes.

      PubDate: 2017-11-15T20:10:38Z
  • Biomechanical simulation of healing process of fractured femoral shaft
           applied by composite intramedullary nails according to fracture
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Ali Mehboob, Seung-Hwan Chang
      Flexible composite implants are receiving increased attention in this modern era of orthopedics for the stabilization of long bone fractures because they facilitate tissue development in calluses. An endochondral ossification process involves generation of calluses, and it is well known that this significantly affects the stabilization and healing of the broken bones. Therefore, the exact configuration of callus formation is highly important for the accurate simulation of bone healing. In this study, finite element analysis was performed to estimate the external callus shape by using the rejection coefficient (RC) algorithm. Regarding the application of a fractured femur by an intramedullary (IM) nail, the bone healing simulation was conducted by employing the biphasic mechano-regulation algorithm according to the fracture type (transverse (0°) and oblique (35°)), fracture location (proximal, medial, and distal ends), and nail property. The simulation results revealed that a glass/polypropylene fabric composite (Twintex [0]2nT) IM nail, which has the similar Young’s modulus to the cortical bone, provided the most appropriate bio-mechanical environment for bone healing.

      PubDate: 2017-11-15T20:10:38Z
  • Experimental study of CFRP strengthened steel columns subject to lateral
           impact loads
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Majid M.A. Kadhim, Zhangjian Wu, Lee S. Cunningham
      In both building and civil engineering structures, the occurrence of impact loading to column elements can be a significant issue, particularly in regard to disproportionate collapse. For existing structures vulnerable to impacts, the development of appropriate strengthening techniques is key to extending service life and improving robustness. In the case of structural steelwork, composites such as carbon fibre reinforced polymer (CFRP) offer a promising means of retrofitting and improving performance under impact. Towards this, the present study experimentally investigated a total of 12 square hollow section (SHS) columns under impact loads. The test series included both unstrengthened and CFRP strengthened samples with different fibre orientations with a view to finding the optimum CFRP configuration. As a means of simulating lateral impact on axially loaded elements, a purpose-built test rig was manufactured to apply a compressive preload to the samples prior to impact. Different preloading levels were applied to the samples before they were impacted transversely. The results show that the strengthening effectiveness increased with higher preloading level. The average reduction in the transverse displacement for the strengthened columns tested under 70% preloading level was around 32% compared to the unstrengthened column while this value was about 22% for the columns tested without compressive preload.

      PubDate: 2017-11-15T20:10:38Z
  • Effect of curing time on the fracture toughness of fly ash concrete
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Grzegorz Ludwik Golewski
      This paper presents the results of an experimental investigation carried out to evaluate the compressive strength and fracture toughness of concrete mixtures in which main binder (Ordinary Portland Cement – OPC) was partially replaced with Class F fly ash (FA). OPC was replaced with two percentages (20% and 30%) of FA by weight. Compressive strength and fracture toughness under mode III – K IIIc (torsional loading), were determined at: 3, 7, 28, 90, 180 and 365 days. Test results indicate significant improvement in the strength properties and fracture toughness of mature concrete, by the inclusion of 20% FA as partial replacement of OPC. On the other hand, the additive of FA in the amount of 30% weight of OPC has a beneficial effect on the mechanical parameters of concrete only after half a year ofcuring. The obtained results are significant in the analysis of concrete structures subjected to complex loading, or structures where torsional moment is the basic load.

      PubDate: 2017-11-15T20:10:38Z
  • To the design of highly fracture-resistant composites by the application
           of the yield stress inhomogeneity effect
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): M. Sistaninia, R. Kasberger, O. Kolednik
      Improvement of the fracture toughness by the introduction of thin, soft interlayers is investigated. The mechanism is the strong decrease of the crack driving force when the crack tip is located in the soft region. Based on numerical simulations with the configurational forces concept, it is demonstrated that the fracture toughness of brittle materials can be greatly improved by the introduction of soft interlayers, if the architectural parameters of the multilayer are appropriately chosen. The findings are compared to experimental results of fracture tests conducted on compounds made of high-strength steel as matrix and low-strength steel as interlayer material. The design concept presented in this paper can be applied for various types of composite materials.

      PubDate: 2017-11-15T20:10:38Z
  • Governing failure criterion of short-span hybrid FRP-UHPC beams subjected
           to high shear forces
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Mina Iskander, Raafat El-Hacha, Nigel Shrive
      An experimental investigation into the shear performance of a recently developed hybrid section constructed from a glass fibre reinforced polymer (GFRP) hollow box section with an ultra-high performance concrete (UHPC) flange and a bottom sheet made of steel fibre reinforced polymer (SFRP) or carbon fibre reinforced polymer (CFRP) is presented. This section has superior structural properties compared to sections made from conventional materials. Seven specimens were tested by applying a point load 280 mm from one support over a clear span of 1120 mm to induce shear failure. Two main parameters were investigated, namely, the effect of flange dimensions and the type of reinforcement used as the bottom (tension) sheet. All specimens failed similarly, indicating consistent behaviour for shear failure regardless of the changing parameters. Failure involved crack propagation at the corners of the GRFP box section followed by cracking of UHPC flange. Traditional calculations, based on the elastic analysis, of the shear stresses at the failure point are presented showing that high shear stresses are not the only cause of the mode of failure observed. The cause of failure is interpreted using a simple finite element analysis. Given the cause of failure, special consideration should be given to the design of the fibre orientation at the corner regions of such box sections.

      PubDate: 2017-11-15T20:10:38Z
  • Multi-objective multi-laminate design and optimization of a Carbon Fibre
           Composite wing torsion box using evolutionary algorithm
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Sachin Shrivastava, P.M. Mohite, Tarun Yadav, Appasaheb Malagaudanavar
      The present study aims to minimize the weight of multi-laminate aerospace structures by a classical Genetic Algorithm (GA) interfaced with a CAE solver. The structural weight minimization is a multi-objective optimization problem subjected to fulfilling of strength and stiffness design requirements as well. The desired fitness function connects the multi-objective design requirements to form a single-objective function by using carefully chosen scaling factors and a weight vector to get a near optimal solution. The scaling factors normalize and the weight vector prioritizes the objective functions. The weight vector selection was based on a posteriori articulation, after obtaining a series of Pareto fronts by 3D hull plot of strength, stiffness and assembly weight data points. During the optimization, the algorithm does an intelligent laminate selection based on static strength and alters the ply orientations and thickness of laminae for faster convergence. The study further brings out the influence of mutation percentage on convergence. The optimization procedure on a transport aircraft wing torsion box has showed 29% weight reduction compared to an initial quasi-isotropic laminated structure and 54% with respect to the metallic structure.

      PubDate: 2017-11-15T20:10:38Z
  • Characterizing the off-axis dependence of failure mechanism in notched
           fiber metal laminates
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Jipeng Zhang, Yue Wang, Jiazhen Zhang, Zhengong Zhou, Guodong Fang, Yuan Zhao, Shiming Zu
      Fiber metal laminates (FMLs) are usually more complicated in the failure aspect as compared to their constituents, especially when complex load is applied. In this paper, notched FMLs and the constituents, i.e., the aluminum and glass fiber reinforced plastic (GFRP) were subjected to off-axis tensile loading to evaluate the failure mechanism. Initial attention was paid on the off-axis dependence of mechanical responses, especially on its relation to the notch size. As expected, off-axis dependence of notched strength and notch sensitivity were closely related to the notch size, but different for GFRP laminates and FMLs due to their different damage behavior. Finite element model was employed to predict accurately the mechanical responses of FMLs, particularly for elucidating the damage mechanism. Failure of notched FMLs under off-axis loading was a combined transverse fracture and shear-off, while it was shear-dominated in notched GFRP laminates. Transverse fracture in aluminum appeared first, followed by the fiber breakage, which was postponed by the extensive subcritical damage. Thereafter, shear-failure in fiber and aluminum layers were encountered instantaneously at the descending part. Thus, the critical failure of off-axis notched FMLs was still tension-dominated as that in the on-axis case, but aluminum played the critical role.

      PubDate: 2017-11-15T20:10:38Z
  • Nondestructive evaluation of GFRP composite including multi-delamination
           using THz spectroscopy and imaging
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Dae-Hyun Han, Lae-Hyong Kang
      We utilize a fiber-coupled terahertz time-domain spectroscopy system (THz-TDS) based on photoconductive antennas to visualize multi-delamination and their thickness in a glass-fiber-reinforced polymer (GFRP) composite plate. We simulate a hidden multi-delamination by inserting a Teflon film in the GFRP composite plate that is fabricated using the vacuum-assisted resin transfer molding (VARTM) process. Reflected or transmitted terahertz (THz) waves are recorded from GFRP samples mounted on the x–y linear motorized stage during the investigation. The x–y linear motorized stage is driven in steps of 0.2 mm, thereby allowing us to scan the sample. We examine and compare the performances of the THz time-domain visualization (TTV) and THz frequency-domain visualization (TFV) algorithms to evaluate their characteristics for the visualization of defects. The thickness of the GFRP sample and multi-delamination is estimated using the reflection geometry method. Finally, we confirm that the hidden multi-delamination of the GFRP sample has been successfully visualized in the B- and C-scans. In addition, the thicknesses of the GFRP sample and the simulated delamination as compared with the experimental values exhibit a close consistency.

      PubDate: 2017-11-15T20:10:38Z
  • Characterization of elastic constants of anisotropic composites in
           compression using digital image correlation
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Olli Orell, Jyrki Vuorinen, Jarno Jokinen, Heikki Kettunen, Pertti Hytönen, Jani Turunen, Mikko Kanerva
      Experimental determination of elastic constants of anisotropic composite laminates in all orthogonal directions is generally a complex process. In this paper a simple direct technique to determine a broad set of elastic moduli is presented based on compression testing of a prism sample. Digital image correlation is used to measure the full-field deformations that allow the determination of Young’s moduli and all six Poisson’s ratios for the three orthogonal directions based on a single sample. Finite element model is used in evaluation of the effect of friction on the measured properties. In addition to quantitative characterization of the material properties, local strain mapping is used in qualitative evaluation of the sample structures.

      PubDate: 2017-11-15T20:10:38Z
  • Combined effects of steel fiber and coarse aggregate size on the
           compressive and flexural toughness of high-strength concrete
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Seok-Joon Jang, Hyun-Do Yun
      This paper investigates the effects of steel fiber content and coarse aggregate size on the mechanical properties of high-strength concrete with a specified compressive strength value of 60 MPa. The paper also explores the correlation between the compressive and flexural toughness of high-strength steel fiber-reinforced concrete (SFRC). For this purpose, twelve high-strength SFRC mixtures with four fiber volume fraction of steel fiber (Vf  = 0.5%, 1.0%, 1.5%, and 2.0%) and different aggregate sizes were designed and fabricated. Compressive and flexural tests for each concrete mixture were conducted, and the test results were used to investigate the effects of steel fiber volume fraction and aggregate size on the compressive and flexural toughness of high-strength SFRC prims. The results indicate that the mechanical properties of SFRC are related more closely to volume fraction than to aggregate size. The compressive and flexural toughness ratios of the SFRC significantly improved with an increase in fiber content. Also, equations that are suggested to determine the compressive toughness ratio based on the equivalent flexural strength ratio were used to predict the mechanical properties of the SFRC in this study.

      PubDate: 2017-11-15T20:10:38Z
  • Modeling the axial compressive stress-strain behavior of CFRP-confined
           rectangular RC columns under monotonic and cyclic loading
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Haytham F. Isleem, Daiyu Wang, Zhenyu Wang
      This paper presents a stress-strain model for rectangular reinforced concrete (RC) columns confined with carbon fiber-reinforced polymer (CFRP) composites and subjected to cyclic axial compression. The model is mainly based on experimental observations and results from a series of tests reported in the companion study, in which 24 large-size CFRP-confined rectangular unreinforced and reinforced concrete columns under monotonic and cyclic axial compression were tested. Relative experimental results compiled from the available literature are also used. The test database covers unconfined concrete compressive strengths ranging from 17.6 MPa to 51.5 MPa and cross-sectional side lengths ranging from 90 mm to 400 mm. The proposed stress-strain model is composed of three main components: (1) a monotonic stress-strain model for the envelope curve of cyclic response; (2) a parabolic expression for the unloading path; and (3) a straight line for the reloading path. The model also considers the effects of key parameters including cross-sectional size, aspect ratio, effective rupture strain of the CFRP, and internal longitudinal and hoop steel reinforcement. The performance of the model is finally verified through comparison of predictions made by this model with selected test results, as well as the predictions of more than 20 models of other researchers.

      PubDate: 2017-11-15T20:10:38Z
  • Multi-objective structural-acoustic optimization of beams made of
           functionally graded materials
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Meng-Xin He, Jian-Qiao Sun
      This paper presents a study of multi-objective structural-acoustic optimization of elastic beams made of functionally graded materials. The goal of this research is to discover the potentials to design multi-objective optimal volume fraction for better acoustic performance. The transfer matrix method is applied to obtain the structural-acoustic response of functionally graded beams. The hybrid of particle swarm optimization and cell mapping method is used to search for the Pareto optimal solutions. Two well-known distribution laws of material distribution are considered and compared with the spline interpolation of material distribution when spatially sampled material properties are used as design variables. Several cases are studied to demonstrate the multi-objective optimal design of functionally graded beams.

      PubDate: 2017-11-15T20:10:38Z
  • Damping vibration analysis of graphene sheets on viscoelastic medium
           incorporating hygro-thermal effects employing nonlocal strain gradient
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Farzad Ebrahimi, Mohammad Reza Barati
      In the present article, a nonlocal strain gradient plate model is developed for damping vibration analysis of viscoelastic graphene sheets under hygor-thermal environments. For more accurate analysis of graphene sheets, the proposed theory contains two scale parameters related to the nonlocal and strain gradient effects. Graphene sheet is modeled via a two-variable shear deformation plate theory needless of shear correction factors. Governing equations of a nonlocal strain gradient graphene sheet on viscoelastic substrate are derived via Hamilton’s principle. Differential Quadrature Method (DQM) is implemented to solve the governing equations for different boundary conditions. Effects of different factors such as temperature rise, nonlocal parameter, length scale parameter, elastic foundation and aspect ratio on vibration characteristics a graphene sheets are studied.

      PubDate: 2017-11-15T20:10:38Z
  • Experimental and numerical investigation on the impact behavior of
           dual-core composite sandwich panels designed for hydraulic turbine
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): R. Ouadday, A. Marouene, G. Morada, A. Kaabi, R. Boukhili, A. Vadean
      This paper focuses on the experimental characterization and modeling of the impact behavior of a multi-functional dual core sandwich panel designed for the rehabilitation of hydroelectric turbines. The studied sandwich panel consists of glass fiber reinforced epoxy (GFRE) facesheets and a dual core composed both of alumina trihydrate-filled epoxy (ATH/epoxy) and extruded polystyrene foam (XPS). Low-velocity impact tests are conducted at different impact energies to take into account the presence of debris in the water flow. A 3D numerical model is developed to simulate the impact tests and particularly the energy distribution within the sandwich constituents. A good correlation is achieved between the experimental data and numerical predictions. The dual core sandwich construction placed on a rigid foundation undergoes both local and global deformation under impact loading. The experimental results show that for the tested impact energy range, the sandwich panel absorbs approximately 50% of the impact energy. Although the top facesheet and the ATH/epoxy core govern the initial impact behavior, the recoverable compression deformation of the XPS foam core is the major energy absorption mechanism. This statement is well supported by the numerical simulation.

      PubDate: 2017-11-15T20:10:38Z
  • Effect of superplasticizer type and siliceous materials on the dispersion
           of carbon nanotube in cementitious composites
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): G.M. Kim, I.W. Nam, H.N. Yoon, H.K. Lee
      The influences of superplasticizers and siliceous materials on the dispersion of carbon nanotube (CNT) in cementitious composites were investigated. Three types of superplasticizer were used, and the siliceous materials such as silica fume and nano-silica were utilized as dispersion agents. The dispersion characteristics of CNT in the state of aqueous solution were explored via the UV–Vis spectra, and the zeta potential, while those of CNT in the cementitious matrix were investigated via the electrical characteristics of the CNT-incorporated cementitious composites and scanning electron microscopy images. The dispersion mechanism of CNT induced by the superplasticizers and the siliceous materials was thoroughly examined. The superplasticizers containing polycarboxylate were effective to disperse CNT in cementitious composites compared to other types of superplasticizers used here. The addition of silica fume to cementitious composites utilizing the superplasticizers with polycarboxylate was further improved the dispersion of CNT, while nano-silica did not improve the dispersion of CNT.

      PubDate: 2017-11-15T20:10:38Z
  • Comments on “High strain rate response of nanofiber interlayered
           structural composites” [Compos. Struct. 168 (2017) 47–55]
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): S. Gurusideswar

      PubDate: 2017-10-18T03:40:15Z
  • Analytical and finite element studies on hybrid FRP strengthened RC column
           elements under axial and eccentric compression
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): M. Chellapandian, S. Suriya Prakash, Amirtham Rajagopal
      Analytical and finite element studies on the behavior of Reinforced Concrete (RC) column elements strengthened using a hybrid Carbon Fiber Reinforced Polymer (CFRP) laminates and externally bonded fabric is explored in this study. The main objective of this study is to evaluate the effect of hybrid strengthening on the initial and post-cracking stiffness, peak and post-peak behavior, and change in failure modes of RC column elements. Both axial and eccentric loads are considered in this study. Experimental program is carried out by testing the column elements with and without different FRP strengthening. Analytical predictions are obtained using the strain compatibility approach based on the existing constitutive models for unconfined and confined concrete, steel and FRP composites. A numerical model of column elements is developed using a commercial software ABAQUS. The predictions obtained from the analytical and FE analysis were validated with the experimental results. Analytical and FE predictions exhibited a fair correlation with discrepancy of less than 5% when compared to test results. A parametric study is carried out using the validated FE analysis by varying the CFRP fabric ratio, CFRP laminate ratio and their hybrid combinations. Hybrid strengthening technique is found to be more efficient in improving the initial and post-cracking stiffness, strength and ultimate displacement ductility of RC column elements under compression.

      PubDate: 2017-10-18T03:40:15Z
  • Analysis of the mechanical behavior of composite T-joints reinforced by
           one side stitching
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): J. Bigaud, Z. Aboura, A.T. Martins, S. Verger
      T-joints stiffeners made from carbon/epoxy composites have been increasingly applied in aeronautical structures, however as majority of the carbon fiber reinforced structures, they have faced with delamination problems. Through-the-thickness reinforcements for laminate composites have been studied as manner to increase transversal strength, especially reducing delamination. In the present work, carbon/epoxy T-joints reinforced transversally by one side stitching (OSS) and molded on Resin Transfer Molding (RTM) process have been performed as well as the reference (unstitched T-joints). The stitching position were designed after analysis of the unstitched T-joints by means of strain field on Digital Image Correlation (DIC) under pull-off test to better improve the areas submitted to large strain. Also, the stitched samples were mechanically tested in pull-off mode and were analyzed during tests by in situ microscopy and post-failure on Scanning Electron Microscopy .The energy release was better contained in the stitched structures especially in the critical region (delta-fillet), due to crack bridging that improved the delamination toughness. Otherwise, the stitch pattern generated by OSS process changed the strain fields asymmetrically when analyzed on DIC during tests. The stitched T-joints showed greater ultimate strength (25%) and load recovery post ultimate strength (19%) in comparison to the reference.

      PubDate: 2017-10-18T03:40:15Z
  • Failure analysis of adhesively bonded steel corrugated sandwich structures
           under three-point bending
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Ye Yu, Liang Ying, Wen-bin Hou, Ping Hu, Xiu-xian Jia, Ganiy Akhmet
      Failure modes and critical loads for adhesively bonded steel corrugated sandwich structure under three-point bending in both longitudinal and transverse direction are investigated. An analytical model considering both adhesive joint effects and classic beam theory is developed for predicting the failure modes and stresses in each member of the sandwich structure. Then the corresponding experiments and the numerical analysis by using cohesive zone model are also carried out. The experimental data, numerical results and the analytical predictions are all agree well with each other. Furthermore, based on the analytical expressions, the failure mechanism maps for three-point bending are constructed to get better understanding of failure modes and minimum weight design. Besides, the effects of adhesive parameters on failure modes and stress distribution are further studied by using the analytical model.

      PubDate: 2017-10-18T03:40:15Z
  • Thermographic stepwise assessment of impact damage in sandwich panels
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Chiara Colombo, Mohamed Harhash, Heinz Palkowski, Laura Vergani
      Metal-polymer-metal sandwiches can find promising applications in the automotive field thanks to their lightweight and formability. The paper focuses on the effect of low velocity impacts on the residual mechanical behavior. Experimental stepwise tests are run on undamaged and impacted specimens with different combinations of thickness and grade for the outer steel skins and the inner polymeric core. Surface temperature evolution is thermally monitored during the tests with the aim to characterize the induced damage and to identify a parameter able to quantify the residual strength of the panel. Several approaches have been considered. The analysis of the thermal amplitude trend with the lock-in thermography evidences a variation in the thermal behavior of the specimens, defining a corresponding damage stress σD . We found a 20% σD difference between undamaged and damaged specimens. Moreover, impacted specimens experience a temperature and stress concentration at the impact area dependent on the indentation. Based on these results, we evidence the possibility to relate impact indentation with the damage stress estimated by thermography and with the stress concentration factor induced by the impact. Therefore, thermography is a useful and valid tool for post-impact damage detection, monitoring and quantification of these multi-layer sandwich materials.

      PubDate: 2017-10-18T03:40:15Z
  • Auxetic nail: Design and experimental study
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Xin Ren, Jianhu Shen, Phuong Tran, Tuan Duc Ngo, Yi Min Xie
      Under uniaxial compression (tension), auxetic materials would shrink (expand) laterally. It has been speculated that the auxetic property could be used to design superior nails for easier push-in and harder pull-out. In this study, the first auxetic nails are designed, fabricated and experimentally investigated. Pine timber and medium-density fibreboard are selected as testing materials. The push-in and pull-out performance of auxetic and non-auxetic nails is compared by using two key parameters of the maximum compressive force and the maximum tensile force. It is found that the auxetic nails do not always exhibit superior mechanical performance to non-auxetic ones. Also, the small auxetic deformation of one typical designed auxetic nail is revealed by the experimentally validated finite element model. The experimental and numerical results illustrate the limitations of exploiting the auxetic property in the nail application. Some suggestions are provided for more effective designs of future auxetic nails.

      PubDate: 2017-10-18T03:40:15Z
  • A Puck-based localisation plane theory for rate- and pressure-dependent
           constitutive modelling of unidirectional fibre-reinforced polymers
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Daniel M. Thomson, Borja Erice, Hao Cui, Justus Hoffmann, Jens Wiegand, Nik Petrinic
      A new constitutive model is presented that aims to accurately tackle the effects of multiaxial loading, strain rate and hydrostatic pressure on unidirectional FRPs, while doing so in an intuitive and physically-based manner. In this model, it is assumed that yielding occurs primarily due to shear stresses acting on a critical localisation plane while normal compressive stresses on this plane have a strengthening effect similar to pressure effects in a Drucker-Prager model. In this way, the orientation of the localisation plane, which depends on the stress state of the material, deals with the issue of multiaxiality and the pressure-dependency is accounted for by the Drucker-Prager based yield criterion. The main appeal of this approach is that a complex three-dimensional problem is reduced to essentially a case of 2D plasticity, which is conceptually very simple and easier to interpret. In addition, this model is supported by a strong physical basis, as it is constructed from the well-established Mohr-Coulomb and Drucker-Prager theories. A series of experimental results are provided that support the hypotheses on which this theory is based and against which the model has been benchmarked, showing its ability to reproduce the complex observed effects of multi-axial loading, strain-rate and pressure.

      PubDate: 2017-10-18T03:40:15Z
  • New 3-bar prismatic tensegrity units
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Heping Liu, Jingyao Zhang, Makoto Ohsaki
      Various methods have been presented for generating complex tensegrity structures by assembling simple units. Hence, generating new units will in turn benefit in obtaining various shapes of tensegrity structures. In this paper, we present three different new units by adding strings to the well-known 3-bar prismatic tensegrity unit. Analytical solutions are derived for their self-equilibrium analysis. Influences of structural parameters on internal forces of the members are investigated to study properties of the new tensegrity units.

      PubDate: 2017-10-18T03:40:15Z
  • Bending and vibration behaviors of matrix cracked hybrid laminated plates
           containing CNTR-FG layers and FRC layers
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Z.X. Lei, B.B. Yin, K.M. Liew
      The influence of matrix cracks on bending and vibration behaviors of hybrid laminated plates is investigated based on an element-free numerical framework. Carbon nanotube reinforced functionally graded (CNTR-FG) layers and conventional graphite fiber reinforced composite (FRC) layers are selected as layer elements for the considered hybrid laminated plates. To illustrate the degraded stiffness, a matrix-cracked model, namely self-consistent model (SCM), is employed. Based on the first-order shear deformation theory (FSDT), we can obtain the governing equation. An element-free numerical framework is proposed to solve the governing equation for obtaining the bending and vibration solutions. In addition, some selected calculations are furnished to illustrate the influences of matrix crack densities, boundary conditions, material parameters and geometric parameters on the bending and vibration behavior characteristics.

      PubDate: 2017-10-18T03:40:15Z
  • An experimental and numerical investigation on low velocity impact
           response of a composite structure inspired by dragonfly wing configuration
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): A. Arjangpay, A. Darvizeh, M. Yarmohammad Tooski, R. Ansari
      The low velocity impact response of a novel foam-based composite structure inspired by microstructural features of dragonfly wings is investigated through the use of FE model and experiments. A nonlinear progressive damage model of the composite skins is incorporated into the FE code by VUMAT subroutine. Inter-laminar damage is reproduced using interface cohesive elements and the foam core is modeled as a crushable foam material. The numerical results are compared with experimental data acquired by impact testing on bio-inspired structures consisting of E-glass/epoxy skins filled by polyurethane foam, where a good agreement is achieved. To assess the contribution of the sandwich vein on the impact behavior of the structure, a comparison is made between different veiny structures and monolithic laminates with the same materials under low velocity impact. It is concluded that the sandwich vein can limit the damage propagation and makes the rest of the structure remain intact.

      PubDate: 2017-10-18T03:40:15Z
  • Uncertainty analysis in composite material properties characterization
           using digital image correlation and finite element model updating
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Tiren He, Liu Liu, Andrew Makeev
      This work presents an uncertainty analysis on composite material constitutive parameters, which are extracted using digital image correlation (DIC) and finite-element-model-updating (FEMU). The uncertainty is induced by the measurement system noise in the DIC technique and the approximation error in the displacements and strains smoothing algorithm. The covariance matrix of the extracted material constitutive parameters has been given explicitly. Six material constitutive parameters were identified from a customized short-shear experiment simultaneously using an estimated optimal reconstruction mesh size as an illustration. Sensitivity of measurement noise and reconstruction parameter on extracted material properties has been investigated. The effects of region of interest (ROI) and DIC image number on uncertainties of extracted material properties have been addressed. It is suggested that there exist an appropriate ROI and the number of images, from which reliable material parameters can be identified, but much more data used in identification process always lead to smaller standard deviation and COV. It is observed that the material constants used to characterize the in-plane shear stress-strain behavior show strong robustness to the measurement noise. However, the identified longitudinal Young’s modulus is more sensitive to the measurement noise. Another key finding is that the reconstruction parameter in the global finite-element based approximation approach is critical for reliable material properties identification. Its value has to stay close to optimum for guaranteeing reliable identification of material properties.

      PubDate: 2017-10-18T03:40:15Z
  • Mechanical behavior of ultra-high toughness cementitious composite
           strengthened with Fiber Reinforced Polymer grid
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Yu-Zhou Zheng, Wen-Wei Wang, Khalid M. Mosalam, Zhong-Feng Zhu
      A new strengthening composite system, namely Basalt Fiber Reinforced Polymer (BFRP) grid – Ultra-High Toughness Cementitious Composite (UHTCC) for Reinforced Concrete (RC) structures is explored in this paper. Thirty UHTCC specimens internally strengthened with BFRP grid and six similar reference specimens without strengthening were tested to investigate the tensile mechanical behavior. The reinforcement ratio of the BFRP grid (0.17%, 0.68%, and 1.16%) and the mix proportion of the UHTCC were the two main test parameters. The experimental results highlighted two failure modes: 1) rupture or slip off failure of chopped PolyVinyl Alcohol (PVA) fibers at the critical crack sections in the reference specimens, and 2) partial rupture failure of BFRP grid within the UHTCC in all strengthened specimens. Moreover, the relative slip at the interface between the BFRP grid and the UHTCC substrate was not observed during testing. The tensile force capacity of the strengthened BFRP–UHTCC specimens increased by 42% to 172% compared to the reference specimens depending on the reinforcement ratio of the BFRP grid. On the other hand, the tensile force capacity of BFRP–UHTCC specimens slightly decreased by 1% to 14% with the increase of the water-to-cement material ratio of the UHTCC layer from 24% to 38%. Additionally, a stress–strain relationship and strength models of the strengthened specimens are proposed and verified with the test results to predict the tensile mechanical behavior.

      PubDate: 2017-10-11T07:43:48Z
  • 3D-printed multimaterial composites tailored for compliancy and strain
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): M.R. Mansouri, H. Montazerian, S. Schmauder, J. Kadkhodapour
      Co-continuous multimaterial composites are novel types of multifunctional structures. This study focuses on numerical and experimental investigation of the mechanical behavior of 3D periodic single-material cellular D-structure and the corresponding co-continuous composite. Different volume fractions of desired geometry were fabricated by multimaterial fused deposition modeling (FDM) technology and compressive mechanical properties of the samples were obtained by mechanical tests. It was observed that embedding a hyperelastic material to the cellular structure dramatically hindered the shearing bands in localized regions to develop, thereby made it feasible for composite material to undergo larger deformations without failure. Furthermore, it was demonstrated that the soft phase in multimaterial composite induces a homogeneous deformation to cellular structure, which enhances the load-bearing capacity and flexibility of the whole composite. In this paper, it was shown that the co-continuous multimaterial composite provides a well-balanced approach between desired flexibility and load-bearing which is referred to as compliancy. A strain recovery between 82 and 93% was also measured when unloading for multimaterial composite. These integrated properties could be valuable to various engineering applications such as synthetic limbs, soft robotics, and wearable structures as shoes and splints.
      Graphical abstract image

      PubDate: 2017-10-11T07:43:48Z
  • Effect of bending-twisting coupling on the compression and shear buckling
           strength of infinitely long plates
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Christopher Bronn York, Sergio Frascino Muller de Almeida
      This article describes the development of closed form polynomial equations for compression and shear buckling to assess the effect of Bending-Twisting coupling on infinitely long laminated plates with simply supported edges. The equations are used to generate contour maps, representing non-dimensional buckling factors, which are superimposed on the lamination parameter design spaces for laminates with standard ply orientations. The contour maps are applicable to two recently developed databases containing symmetric and non-symmetric laminates with either Bending-Twisting or Extension-Shearing Bending-Twisting coupling. The contour maps provide new insights into buckling performance improvements that are non-intuitive and facilitate comparison between hypothetical and practical designs. The databases are illustrated through point clouds of lamination parameter coordinates, which demonstrate the effect of applying common design heuristics, including ply angle, ply percentage and ply contiguity constraints.

      PubDate: 2017-10-11T07:43:48Z
  • Automatically assembled large-scale tensegrities by truncated regular
           polyhedral and prismatic elementary cells
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Li-Yuan Zhang, Song-Xue Li, Shi-Xin Zhu, Bo-Yang Zhang, Guang-Kui Xu
      As a novel type of reticulated structures, tensegrities have found various applications in science and engineering. In this paper, an ingenious assembly method is developed to construct large-scale tensegrities using truncated regular polyhedral tensegrities and prismatic tensegrities as elementary cells. The truncated polyhedral tensegrities with regular polygons on their surfaces are specified as islands, and the prismatic tensegrities are used as bridges to connect these polygons along different directions. This method allows us to construct many types of large-scale tensegrities satisfying the demands of the size and topology. Based on the node-on-node assembly scheme, Z-based truncated regular octahedral tensegrity and its matching quadruplex prismatic tensegrity are employed to produce representative examples with traditional and untraditional shapes. Their mechanical properties are evaluated from the viewpoints of self-equilibrium, stability, and mechanical responses. Our results help to manufacture demanded large-scale tensegrities with delicate mechanical properties, and may be beneficial to construct composite metamaterials.

      PubDate: 2017-10-11T07:43:48Z
  • Modeling for CFRP structures subjected to quasi-static crushing
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Guohua Zhu, Guangyong Sun, Guangyao Li, Aiguo Cheng, Qing Li
      Carbon fiber reinforced plastic (CFRP) composite materials demonstrate significant promise to further improve weight to performance in automotive engineering. Nevertheless, design of CFRP components for crashworthiness criteria remains rather challenging and typically requires laborious trial-and-error processes. This study aims to promote computational design of CFRP structures by establishing effective constitutive model that is implemented in the commercial finite element code Abaqus/Explicit. Two different numerical models (namely, the single layer shell model and the stacked shell model) were developed to simulate experimental crushing tests on the square CFRP tube. The effects of key parameters for these two FE models were analyzed, respectively. The comparisons of numerical results with experimental data indicated that the 9 layers stacked shell model is capable of reproducing experimental results with relatively higher accuracy. Based on the validated modeling approach, crushing behaviors of several CFRP thin-walled structures with different cross sectional geometries and thicknesses were further explored. The failure modes and key indicators in relation to the structural crashworthiness were investigated for identifying a best possible sectional configuration. It is found that the circular tube shows superior specific energy absorption capacity of all different tubal configurations with the same wall thickness, meaning that the tube with circular section is of good potential asa crashworthy CFRP structure.

      PubDate: 2017-10-11T07:43:48Z
  • Experimental investigation of substandard RC columns confined with SRG
           jackets under compression
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Georgia E. Thermou, Konstantinos Katakalos, George Manos
      This paper aims to explore the behaviour of substandard reinforced concrete (RC) columns confined with Steel-Reinforced Grout (SRG) jackets under monotonically increasing uniaxial compression. A total of 24 specimens of short RC columns of square cross section were designed to fail due to longitudinal reinforcement buckling. Single-layered SRG jackets were applied to 18 of these specimens, whereas the rest served for control without SRG jackets. Parameters of this investigation were the type and density of the steel fabric as well as the corner radius of the cross section. The employed SRG jacketing managed to increase the strength and strain capacity and postpone the buckling of the longitudinal steel bars to occur at higher compressive strain level. Confinement effectiveness with respect to the lateral confining pressure exerted by the used SRG jacketing is discussed along with the observed mode of failure.

      PubDate: 2017-10-11T07:43:48Z
  • Application of Kalman Filter based Neutral Axis tracking for damage
           detection in composites structures
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Rohan Soman, Katarzyna Majewska, Magdalena Mieloszyk, Pawel Malinowski, Wieslaw Ostachowicz
      Structural Health Monitoring (SHM) systems allow early detection of damage which allows maintenance planning and reduces the maintenance cost. The SHM system should be low cost, suitable for continuous monitoring, able to detect small levels of damage, and insensitive to ambient loading, changes in ambient temperature, and measurement noise. Neutral Axis (NA) location is a function of the condition of the structure alone and may be used as a damage sensitive feature. It has been shown that through proper signal processing, NA location is insensitive to measurement noise and ambient temperature changes. This paper aims at validating the use of NA as a damage sensitive feature through experimental study. This paper demonstrates the use of multi-rate Kalman Filter (KF) for accurate estimation of NA under different loading conditions. The methodology was employed on a composite beam instrumented with fiber optic strain sensors. Delamination was introduced in the beam and then progressively increased. The beam was subjected to different loading and temperature conditions for the different damage scenarios. The measured strains were then used for NA tracking. The results show that indeed the NA location may be used as a damage sensitive feature. Some of the loading scenarios were difficult to realise in the laboratory, so these loading scenarios were applied on a validated Finite Element (FE) model of the composite beam. The results indicate that under these dynamic loading scenarios, NA may be used for SHM. Based on the results it can be concluded that KF based NA tracking may be applied to structures for in-service SHM.

      PubDate: 2017-10-11T07:43:48Z
  • Shear strengthening of steel plates using small-diameter CFRP strands
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Hamid Kazem, Sami Rizkalla, Akira Kobayashi
      This paper presents the results of a comprehensive research program, including experimental and analytical studies, to examine the use of small-diameter CFRP strands for shear strengthening of steel structures and bridges. The experimental program examined the effectiveness of the proposed strengthening system to increase the shear capacity of steel plates subjected to pure shear stresses using a unique test set up. A nonlinear finite element analysis (FEA), calibrated the experimental results, was used to study parameters which were not included in the experiments. Research findings indicated that the proposed system is effective for shear strengthening of steel structures and eliminated the typical debonding failure commonly observed by CFRP laminates.

      PubDate: 2017-10-11T07:43:48Z
  • Large deformation of an auxetic structure in tension: Experiments and
           finite element analysis
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Jianjun Zhang, Guoxing Lu, Zhihua Wang, Dong Ruan, Amer Alomarah, Yvonne Durandet
      The present paper reports on the post-yield behaviors of an auxetic structure, honeycomb with representative re-entrant topology. Specimens were made of stainless steel and polymer, respectively. Quasi-static uniaxial tensile tests were conducted in the two principal directions, followed by simulations using the commercial code – ABAQUS 6.11-2. The deformation, tensile stress-strain curves and Poisson’s ratio were of interest. A good agreement was observed between the numerical simulations and the experimental results. Subsequently, the effect of cell wall thickness and initial cell angle was studied by means of finite element analysis. An analytical equation was also given for the yield stress of such materials under tension.

      PubDate: 2017-10-11T07:43:48Z
  • Nacre-inspired design of CFRP composite for improved energy absorption
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Zhibo Xin, Xiaohui Zhang, Yugang Duan, Wu Xu
      Discontinuous unidirectional fiber-reinforced composites are shown to possibly exhibit pseudo-ductile failure that is lacking in continuous fiber composites. The aim of this paper is to use a discontinuous and interdigitated design strategy which mimicks the nacre structure to improve the specific energy absorption (SEA) of a carbon/expoxy composite tube. Quasi-static axial compressive experiment is combined with a digital image correlation system to analyze the failure process of the specimens. Four kinds of tubular specimens which are based on different ply cut intervals and distributions are fabricated and crushed. The load-crushed displacement curves and the SEA values are obtained showing that circular shaped continuous ply cuts result is the highest fluctuation of the compressive force. Moreover, the tubes with helical and nacre mimicking ply cut structures result in a flatter load-crushed displacement curve. This work demonstrates that in a crush process, unidirectional composites with a well-designed discontinuity at the ply level can improve the SEA over 51% as compared to the unidirectional continuous tubes.

      PubDate: 2017-10-11T07:43:48Z
  • Experimental and numerical studies on indentation and perforation
           characteristics of honeycomb sandwich panels
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Guangyong Sun, Dongdong Chen, Xintao Huo, Gang Zheng, Qing Li
      Aluminum sandwich panels with honeycomb core have been widely used as energy absorption structure in lightweight design. This study aimed to characterize the indentation and perforation behaviors of sandwich structures with different geometric configurations. The specimens with four characteristic geometric variables, namely, facesheet thickness, core height, honeycomb core thickness and side length of hexagon cell were tested experimentally. Photographs of cross-sectional view near the loading area and failure modes in the tests were investigated in detail. For the first time, digital image correlation (DIC) technique through an ARAMIS™ real-time optical strain measurement system was adopted for capturing the deformation process of lower skin by acquiring the displacement-time data. Three typical damage modes were identified from the force-displacement curves with different geometric parameters and configurations. It was found that the thickness of facesheet has the most significant effects on both force-displacement curves and energy absorption capacity. Changes in the core parameters have relatively small influences in total energy absorption but sizeable effects on the force-displacement curve and failure modes. A finite element model for predicting damage evolution was also developed and validated through the force-displacement relation and deformation process on the bottom skin. The damage mechanisms of the sandwich panel subject to quasi-static indentation and perforation were analyzed through the numerical models. The present study contributed on understanding how the geometric parameters affect the characteristics of indentation and perforation, thereby providing useful guidelines for its potential applications in impact engineering.

      PubDate: 2017-10-11T07:43:48Z
  • Load transfer mechanisms in CFRP ground anchors with multi-strap ends
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Haifeng Fan, Anastasios P. Vassilopoulos, Thomas Keller
      An investigation of the load-transfer mechanism in carbon fiber-reinforced polymer (CFRP) ground anchors with multi-strap ends was conducted based on experimental and numerical studies of one- and two-strap anchors. Differences in the strap geometry, i.e. different curvature distributions and transitions from the rod to the strap cross section, and different strap numbers only influenced the local load transfer from the straps to the grout, but not the global pull-out behavior. At higher loads, frictional load transfer along the straps occurred only in the outer strap; the friction was not sensitive to confinement variations provided by different rock types. The load transfer at the strap division, however, was proportional to the confinement level. An empirical model was derived to predict the load transfer in multi-strap anchors and applied to design a new three-strap anchor with a targeted capacity of 2500 kN.

      PubDate: 2017-10-11T07:43:48Z
  • Thermomechanical deflection and stress responses of delaminated shallow
           shell structure using higher-order theories
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Chetan Kumar Hirwani, Subrata Kumar Panda, Trupti Ranjan Mahapatra
      The deflection responses of the damaged doubly curved shallow shell panels under the combined thermomechanical loading are investigated numerically in this article. The debonded layered structures are modeled mathematically using two higher-order displacement kinematic theories and solved via finite element method. The separation between the consecutive layers is included using two sub-laminate approaches in the current model including the intermittent displacement continuity conditions. Further, the weak form of the equilibrium equation for the deflected shell panel structure under the combined action of loading is achieved via two-dimensional nine noded isoparametric Lagrangian elements. The responses are obtained by minimising the total potential energy expression with the help of an original computer code (MATLAB) in association with the currently developed mathematical models. The consistency of the present numerical solutions is demonstrated by conducting the convergence test and the validity of the models checked through the proper comparison test. Lastly, some new examples are solved using the current models to show the consequence of the delamination (size and position) including the other structural parameters (the side to thickness ratio, the length to width ratio, the curvature ratio and the boundary condition) on the deflection responses under the influence of thermomechanical loading.

      PubDate: 2017-10-11T07:43:48Z
  • Design, manufacturing, and testing of a variable stiffness composite
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Mohammad Rouhi, Hossein Ghayoor, Jeffrey Fortin-Simpson, Tom T. Zacchia, Suong V. Hoa, Mehdi Hojjati
      Fiber steering is one of the promising capabilities of Automated Fiber Placement (AFP) technology in manufacturing of advanced composite structures with spatially tailored properties. The so-called variable stiffness (VS) composites have considerable scope to outperform their traditionally made constant stiffness (CS) counterparts. However, there are several design and manufacturing challenges to be addressed before practically using them as structural components. In this work we demonstrate the design, manufacturing and testing procedure of a variable stiffness (VS) composite cylinder made by fiber steering. The improved bending-induced buckling performance is the objective of the VS cylinder to be compared with its CS counterpart. The experimental results show that the buckling capacity of the VS cylinder is about 18.5% higher than its CS counterpart.

      PubDate: 2017-10-11T07:43:48Z
  • Mathematical simulation of pultrusion processes: A review
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Alexander A. Safonov, Pierpaolo Carlone, Iskander Akhatov
      A review of computational modelling and simulation of pultrusion processes is presented including such aspects as: resin flow and pressure distribution in a forming die; impregnation of reinforcing fibers; heat transfer and resin reaction; pulling force, stresses and strains development; methods for numerical optimization of the process. Development of models provides deeper knowledge concerning the mechanisms behind the process as well as the influence of constituent materials’ properties and manufacturing parameters. Consequently, accelerated development of pultrusion process, allowing for the manufacturing of geometrically complex profiles is promoted.

      PubDate: 2017-10-11T07:43:48Z
  • An experimental investigation of the mechanical behavior and damage of
           thick laminated carbon/epoxy composite
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Abderrahmane Djabali, Lotfi Toubal, Redouane Zitoune, Saïd Rechak
      In this study, mechanical behavior and damage of thick laminated carbon/epoxy composite are investigated through static and fatigue three-point bending tests. In order to supply a maximum of information about the mechanical behavior of these materials, which have been little studied in the literature, and to provide an accurate description of the different mechanisms involved during their damage process, three non-destructive evaluation and monitoring techniques were used in this study. The acoustic emission for damage assessment, identification, and their threshold detection, the infrared thermography for fatigue damage evaluation and fatigue limit estimation and the digital image correlation for strain and displacement fields measurements.

      PubDate: 2017-10-11T07:43:48Z
  • Modeling of honeycombs with laminated composite cell walls
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Ruoshui Wang, Jyhwen Wang
      Honeycombs are versatile structures. They have been widely employed in industries where the characteristics of high stiffness, high buckling resistance, large shock absorption and light weight are required. To explore the potential of honeycombs in various mechanical applications, this paper proposes a novel honeycomb with composite laminate cell walls in order to provide wider selection of constituent materials, improved specific stiffness and distinct cell wall surfaces. Analytical homogenization model of this special type of honeycombs is established by modeling the locally heterogeneous honeycomb as a homogeneous orthotropic bulk. Both full-detailed and homogenized models are built and tested using finite element analysis, and the results showed that the analytical model has excellent accuracy in property prediction at a relatively small computational cost. Parametric studies are also conducted to investigate the effect of thickness and elastic moduli of the cell wall plies on the structure’s overall mechanical response. Based on the results, suggestions on property optimizations are discussed.

      PubDate: 2017-10-11T07:43:48Z
  • Effect of stiffener damage caused by low velocity impact on compressive
           buckling and failure modes of T-stiffened composite panels
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Wei Sun, Zhidong Guan, Tian Ouyang, Riming Tan, Xiaodan Zhong
      Effect of stiffener damage caused by Low Velocity Impact (LVI) on compressive buckling and failure load of the three T-stiffened composite panel was studied by experiment in this paper. Stiffener damages were introduced at four impact energy levels with the impact position located on the panel side over the middle stiffener. The impact experimental results show that the impact energy inducing the initial damage of the stiffened panel is about 34 J. With the increase of impact energy, the damage of the panel is slighter than Barely Visible Impact Damage (BVID), while the stiffener damage and stiffener/panel debonding are serious. The panel dent will not be visible until the stiffener is completely fractured under a higher energy impact. Compression after Impact (CAI) experimental results show that although the initial compression stiffness of the stiffened panel is not affected by the stiffener damage, the compressive stiffness decreases with the increase of compressive load due to the damage propagation of the impacted stiffener and buckling of panel. The failure loads decrease significantly when the damage of stiffener and the stiffener/panel debonding occur as the result of LVI, with a maximum drop of 44% compared to the undamaged specimen.

      PubDate: 2017-10-11T07:43:48Z
  • A simple first-order shear deformation shell theory for vibration analysis
           of composite laminated open cylindrical shells with general boundary
    • Abstract: Publication date: 15 January 2018
      Source:Composite Structures, Volume 184
      Author(s): Qingshan Wang, Dong Shao, Bin Qin
      This paper presents, for the first time, a simple first-order shear deformation shell theory (S-FSDST) for free and transient vibration analysis of composite laminated open cylindrical shells with general boundary conditions. By partitioning the radial displacement into bending and shear components, the present theory contains only four unknowns and can be regarded as an enhanced classical shell theory with the consideration of the effects of shear deformation and rotary inertia terms. The governing equations and appropriate boundary conditions are derived from Hamilton’s principle. To obtain natural frequencies and transient responses accurately, the method of reverberation ray matrix (MRRM) is employed based on the obtained exact closed-form solutions. The artificial spring technology is adopted to achieve the general boundary conditions. Accordingly, the scattering matrix is redefined in MRRM to make it suitable for different boundary cases. The excellent accuracy, reliability and efficiency of the present theory and approach are verified by examining the free and transient vibrations of composite laminated open cylindrical shells under various combinations of classical and non-classical boundary conditions. Meanwhile, a variety of new parameter studies regarding the influence of the boundary conditions, geometry parameters, lamina number, material properties and loading forms are performed in detail.

      PubDate: 2017-10-11T07:43:48Z
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