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Composites Part B : Engineering
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  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1359-8368
Published by Elsevier Homepage  [3159 journals]
  • Meshless modeling of bending behavior of bi-directional functionally
           graded beam structures
    • Abstract: Publication date: 15 December 2018Source: Composites Part B: Engineering, Volume 155Author(s): Jiao Li, Yanjin Guan, Guangchun Wang, Guoqun Zhao, Jun Lin, Hakim Naceur, Daniel Coutellier Bi-directional Functionally Graded Materials (FGMs) is of more and more focus in special engineering application like aerospace craft at high altitude and speed. In this paper, bending analysis of this type Functionally Graded Beam (FGB) is performed by a proposed meshless Total Lagrangian (TL) Corrective Smoothed Particle Method (CSPM) which owns more capability in accuracy and stability than the classical Smoothed Particle Hydrodynamics (SPH) method. This method is validated by comparison of the bending deformation with analytical method, ABAQUS and a self-programmed finite element code. The influence of the gradient indexes and boundary conditions on the deformation behavior is also investigated. The method is proved to be more precise and stable than the semi-analytical and FE results when dealing with power-law bi-directional FGB.
       
  • Facile fabrication of silver decorated polyarylene ether nitrile
           composites micro/nanospheres via microemulsion self-assembling
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): Dawei Zhang, Ruoyu Zhang, Xiaohong He, Kun Jia, Xiaobo Liu Although soft micro/nanoreactors obtained from amphiphilic block co-polyolefin are intensively used for metallic nanoparticle synthesis, the intricate crosslinking after self-assembling of copolymers is an indispensable step. In this work, an amphiphilic block copolymer made of aromatic macromolecular with rigid backbone structures (i.e. polyarylene ether nitrile, PEN) is explored to formulate a robust micro/nano-reactor for direct silver nanoparticles (Ag NPs) synthesis without any crosslinking step. We show that the polymeric micro/nanoreactors can be fabricated in both microemulsion and reverse microemulsion system. More importantly, Ag NPs with modulated morphology and optical properties can be in-situ synthesized using these PEN micro/nanoreactors, which is due to the coordination between Ag+ and pendant cyano/sulfonate groups of PEN. Interestingly, the anisotropic polygonal plate-like hybrid nanostructures are obtained via the optimization of nucleation and growth kinetics of Ag NPs using PEN nanoreactor in the water-in-oil W/O reverse microemulsion. Based on these results, the present work would open the way for the facile fabrication of soft micro/nanoreactors for plasmonic nanostructures synthesis using amphiphilic block-copolymers with rigid molecular structures.
       
  • Fabrication of polymer composite films with carbon composite nanofibers
           doped MWNTs-OH for multilevel memory device application
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): Yuanyuan Liu, Jinghua Yin, Xiaoxu Liu, Xiaofeng Zhao, Minghua Chen, Jialong Li, He Zhao, Congcong Zhu, Bo Su Novel carbon composite nanofibers with hierarchical microstructure were synthesized using electro-spinning and carbonization (SC) techniques, and were combined into polyimide matrix based on in-situ polymerization method. The resulted polyimide composites exhibit multilevel resistive switching behavior (MRSB) for memory storage applications, with a favorable ON/OFF current ratio and a high retention time at an operating voltage less than 3 V. A hierarchical microstructure can be observed by SEM, TEM and SAXS tests, which was formed with different sizes between the hydroxyl multi-walled carbon nanotubes (MWNTs-OH), carbon nanofibers and PI matrix, influencing on the MRSB of the composite films. A physical model based on the molecular orbit energy level was utilized to investigate how the microstructures acting as charge transmission layers affect the MRSB. This result provides a new strategy for further improving the high density storage of polymer multilevel switching memory storage device.
       
  • Vibration of FG magneto-electro-viscoelastic porous nanobeams on
           visco-Pasternak foundation
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): Hu Liu, Hua Liu, Jialing Yang In this paper, the size-dependent vibrational behaviors of functionally graded (FG) magneto-electro-viscoelastic nanobeams in the presence of porosities and embedded in the viscoelastic medium are studied based on the nonlocal Timoshenko beam theory in conjunction with the Kelvin-Voigt viscoelastic model. The viscoelastic medium is modeled as a visco-Pasternak foundation with consideration of both shear modulus and medium damping coefficient. The FG material properties are supposed to vary along the thickness direction in a power-law exponent form, and two types of porosity distributions are considered. The present model is validated by comparison with several existing theories and a good agreement is achieved. Parametric studies are carried out to investigate the coupling influences of the nonlocal parameter, FG power-law index, porosity volume fraction, porosity distribution, boundary condition, structural damping coefficient and viscoelastic foundation parameters, as well as electric voltage and magnetic potential on the vibrational performance of FG magneto-electro-viscoelastic porous nanobeams. The results are helpful for the design and applications of nano-electro-mechanical systems (NEMS).
       
  • High selective production of 5-hydroxymethylfurfural from fructose by
           sulfonic acid functionalized SBA-15 catalyst
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): Lei Wang, Libo Zhang, Hongyi Li, Yubo Ma, Ronghui Zhang A mesoporous SBA-15 supported sulfonic acid catalyst (SBA-15-SO3H) was successfully prepared and used for the selective conversion of fructose to 5-hydroxymethylfurfural (HMF). Up to 96% of HMF selectivity with 100% fructose conversion was obtained under mild conditions (120 °C, 60 min, DMSO as solvent). Solvent effect, reaction time, reaction temperature and fructose-to-catalysts mass ratio have been investigated. The SBA-15-SO3H solid acid catalyst can be separated from the reaction mixture after reaction and reused by simple centrifugalization, and 100% fructose conversion with 95% HMF yield could be retained. Further, reaction activation energy of 56.4 kJ/mol has been fitted with kinetic analysis, which means that the dehydration of fructose into HMF is relative easier over SBA-15-SO3H catalyst in this work. Besides, X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM) measurements reveal that the –SO3H grafting on the SBA-15 surface have no obvious influence on its mesoporous structure even after five catalytic cycles, and acid site measurements demonstrate that there was no significant loss of acid site concentration, indicating high catalytic stability. This fruit give a useful reference to chemical engineering and materials.
       
  • Development and characterisation of dynamic bi-phase (epoxy/PU) composites
           for enhanced impact resistance
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): Muhammad Kashif Bangash, Alaitz Ruiz de Luzuriaga, Jon Aurrekoetxea, Nerea Markaide, Hans-J. Grande, Monica Ferraris The thermosets are non-repairable and non-recyclable and non-repairable polymers. However, the introduction of reversible/dynamic chemical bonds into polymer networks has overcome such limitations of the thermoset composites. In this study, utilizing the dynamic polymer systems, a new approach to enhance the impact resistance of thermoset composites is adopted. Separate CFRP laminates produced with dynamic epoxy and dynamic PU resin systems are joined in three different configurations to obtain dynamic two-phase composites with repairable, recyclable, self-healing and enhanced impact resistance properties. The bi-phase dynamic composites were characterised for structural, thermal, flexural and impact properties in comparison to a reference dynamic single-phase epoxy composite.Graphical abstractImage 1
       
  • Bending strength of CFRP laminated adhesive joints fabricated by
           vacuum-assisted resin transfer molding
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): Mahmoud R. Abusrea, Seung-Wook Han, Kazuo Arakawa, Nak-Sam Choi The laminated joints used in this work were adhesive joints constructed using two dry carbon fiber halves. Some improvements were introduced to the joints to enhance their bending strength performance: stitching of the two halves together by fiber bundles and inserting extra carbon fiber covers in the joint connection. We studied three adhesive joints: a conventional basic and two improved laminated joints. All joint specimens were fabricated using a vacuum-assisted resin transfer molding (VARTM) process. The joints were evaluated with a bending test, and were compared to the bending strength of a jointless carbon fiber reinforced plastic (CFRP) laminate. Two acoustic emission (AE) sensors were placed on the specimen to monitor the fracture progresses during the test. The improved laminated joints, stitched and multiple-cover overlapped joints, showed enhanced bending strength and joint efficiency. The improvement depended significantly on the number of carbon fiber layers. The maximum increase was 24% for the stitched laminated joint of 5 layers and 58% for the multiple-overlapped joint of 6 layers, respectively. Such high joint efficiency was due to the effect of the carbon fiber reinforcement on the joints, by which many carbon fibers supported the strength in advance of reaching the maximum load point, as confirmed by AE measurement analysis.
       
  • Numerically-aided 3D printed random isotropic porous materials approaching
           the Hashin-Shtrikman bounds
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): O. Zerhouni, M.G. Tarantino, K. Danas The present study introduces a methodology that allows to combine 3D printing, experimental testing, numerical and analytical modeling to create random closed-cell porous materials with statistically controlled and isotropic overall elastic properties that are extremely close to the relevant Hashin-Shtrikman bounds. In this first study, we focus our experimental and 3D printing efforts to isotropic random microstructures consisting of single-sized (i.e. monodisperse) spherical voids embedded in a homogeneous solid matrix. The 3D printed specimens are realized by use of the random sequential adsorption method. A detailed FE numerical study allows to define a cubic representative volume element (RVE) by combined periodic and kinematically uniform (i.e. average strain or affine) boundary conditions. The resulting cubic RVE is subsequently assembled to form a standard dog-bone uniaxial tension specimen, which is 3D printed by use of a photopolymeric resin material. The specimens are then tested at relatively small strains by a proper multi-step relaxation procedure to obtain the effective elastic properties of the porous specimens.
       
  • Preparation and properties of modified porous starch/carbon black/natural
           rubber composites
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): Xueyu Du, Yucang Zhang, Xuemei Pan, Fanrong Meng, Jianhua You, Zhifeng Wang Starch is considered as a cost-effective, abundant, renewable and environmental-friendly filler for rubber reinforcement via proper modification. In the present study, porous starch (PS) was modified by esterification with dodecenyl succinic anhydride (DDSA) for preparation of DDSA-modified porous starch (DDSA-PS). The suitable esterification conditions (e.g., temperature, time and dosage of DDSA) were discussed by single-factor experiments as 40 °C, 8 h, and 8 wt % (based on porous starch dry weight), respectively. Later on, a series of DDSA-PS/carbon black (CB)/natural rubber (NR) composites were prepared from the mixture of carbon black and DDSA-PS/NR compound that was pre-processed by co-coagulation of DDSA-PS and rubber latex. When the total filler dosage is constant as 60 parts per hundred rubber (phr), various properties of DDSA-PS/CB/NR composites were investigated by varying the composition ratio of DDSA-PS/CB. The results showed that when the ratio of DDSA-PS/CB was increased, the Payne effect of rubber compounds was attenuated to a large extent as well as the reduction of mechanical properties and wear resistance of vulcanized rubbers. Notably, the rolling resistance and hysteretic property were improved, reflected as the reduction of heat built-up, by incorporation of modified porous starch into the final NR composites. Therefore, DDSA-PS could be served as a promising filler for rubber industry partially instead of carbon black.
       
  • Porous bioceramics produced by inkjet 3D printing: Effect of printing ink
           formulation on the ceramic macro and micro porous architectures control
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Part B: EngineeringAuthor(s): Boqing Zhang, Xuan Pei, Ping Song, Huan Sun, Huiyong Li, Yujiang Fan, Qing Jiang, Changchun Zhou, Xingdong Zhang Hierarchical structures with tailored macro/micro-porosity architecture play an important role in bone tissue regeneration. In 3D printing process, the printing ink formulation will influence on the ceramic macro and micro porous architectures. In this paper, HA powders of nano-sized grains (NP) with diameters of 30–50 nm, air jet milling powders (AP) with diameters of 10–30 μm, and spherical powder (SP) with diameters of 10–50 μm, were used as the initial printing materials in the printing ink formulations. The viscosity and the rheological behavior of printing inks were studied. The microstructure and morphology of the printed scaffold were observed and the mechanical properties of different types of scaffolds were tested. The results showed that the initial printing materials would influence on printing performance, both of the AP and SP inks may print porous scaffolds successfully. However, NP printing inks exhibited dramatic shrinkage and it is not suitable for 3D printing of bioceramics. The printing ink formulation also have effects on the ceramic macro and micro porous architectures and mechanical properties. The maximum compressive strength of SPS were 5.5 MPa, 3.2 MPa and 0.9 MPa with porosities of 60%, 70% and 80%, respectively. As the macroporosity decreases, the mechanical properties of the material would drop dramatically. With the same porosities, the compressive strength of APS were slightly higher than that of the SPS specimens.
       
  • Sulfonated poly ether sulfone/heteropoly acid composite membranes as
           electrolytes for the improved power generation of proton exchange membrane
           fuel cells
    • Abstract: Publication date: Available online 12 August 2018Source: Composites Part B: EngineeringAuthor(s): Ae Rhan Kim, Chul Jin Park, Mohanraj Vinothkannan, Dong Jin Yoo The organic/inorganic hybrid membranes consisting of different concentrations of phosphotungstic acid (PWA) in sulfonated polyether sulfone (SPES) were constructed for the usage as electrolyte in proton exchange membrane fuel cells (PEMFCs). The repulsion applied between the hydrophilic moieties of host and guest components resulted in the porosity of prepared composite membranes. The as-made membranes demonstrated the prompt thermal stability and validated its applications in elevated temperature operation of PEMFCs. When the concentration of PWA was increased to 30 wt% in sulfonated polyether sulfone, the ionic conductivity of the corresponding membrane was increased to 19 mS/cm at room temperature, presumably due to the inherent conductivity of the PWA molecules and the enhanced acidity of sulfonic acid groups in the membranes. The SPES/PWA composite membrane (IEC 1.74 meq/g) comprising 30 wt% of PWA exhibited a maximum ionic conductivity of 116 mS/cm at 90 °C under 100% relative humidity (RH). The as-made SPES/PWA-30 composite membrane exhibited the maximum PEMFC power density of 305 mW/cm2, which validated its potential applications in PEMFCs.
       
  • Experimental study of cfrp-confined reinforced concrete masonry columns
           tested under concentric and eccentric loading
    • Abstract: Publication date: Available online 12 August 2018Source: Composites Part B: EngineeringAuthor(s): Khalid Saqer Alotaibiss, Khaled Galal Using Carbon Fiber Reinforced Polymers (CFRP) jackets to confine existing concrete masonry columns for capacity and ductility enhancement has been approved in axial compression applications. Considering that the majority of columns in practice are loaded under a combination of axial compression load and bending moment, experimental work for testing reinforced concrete masonry columns confined by CFRP jackets under eccentric loading is needed. This paper presents the results of testing 28 half-scale fully grouted reinforced concrete masonry columns under different concentric, eccentric loading conditions and variations in CFRP jacketing. The ability of CFRP jackets to improve the structural performance is evaluated. Axial force-bending moment interaction diagrams of confined reinforced concrete masonry columns are compared against the unconfined masonry columns to quantify the enhancement in strength and moment. The results indicate that increasing the CFRP jacket thickness enhanced the performance of masonry columns regarding axial strain and strength; however, there was a noticeable reduction in strength gain under strain gradient condition upon increasing the eccentricity level. Also, axial force-bending moment interaction diagrams of confined masonry columns showed an increase in the load and the moment capacity compared to that of unconfined masonry columns.
       
  • A new method for an efficient porous carbon/Fe3O4 composite based
           
    • Abstract: Publication date: Available online 12 August 2018Source: Composites Part B: EngineeringAuthor(s): Zhi Liu, Yunxia Lv, Jiyong Fang, Xiaodan Zuo, Chongyang Zhang, Xigui Yue A new strategy was developed for the fabrication of the honeycomb-like porous carbon (HPC) material, involving a liquid-liquid phase separation process and a pyrolysis process. First of all, a novel polyimide containing benzothiazole moieties was designed and synthesized as the carbon precursor. Due to the high glass-transition temperature (Tg, 404 °C) and the low initial thermal decomposition temperature (394 °C) of this specially designed polyimide, the pore structure formed during the phase separation process was well maintained in the following pyrolysis process. As determined by SEM, the product has a honeycomb-like pore structure with a high uniformity. XRD and Raman spectra manifested the resulting carbon material possessed a disordered graphite structure, which can greatly contribute to its EM wave dissipation ability. After modifying HPC with Fe3O4 nanoparticles, the nanocomposites (HPC/Fe3O4) achieved an excellent EM wave absorption performance. At the absorber thickness of 5.5 mm, a minimum reflection loss (RL) value of −20.1 dB was achieved. Moreover, with the variation of the absorber thickness from 1.3 to 5.0 mm, the minimum RL curves in Ku band were all lower than −10 dB. These results demonstrated the polyimide could be an excellent precursor for the synthesis of porous carbon materials with controllable morphology. Additionally, HPC/Fe3O4 could be a promising material for applications in the field of EM wave absorption.Graphical abstractThe polyimide precursor with high glass-transition temperature and low initial thermal decomposition temperature can stay in initial solid state morphology during the carbonization process.Image 1
       
  • Comparison on damage tolerance of scarf and stepped-lap bonded composite
           joints under quasi-static loading
    • Abstract: Publication date: 15 December 2018Source: Composites Part B: Engineering, Volume 155Author(s): Chao Wu, Chen Chen, Li He, Wenyi Yan Scarf or stepped-lap repairs are desirable for composite structures in aerospace, especially where a flush finish is required. Damage tolerance is a critical issue in the repair design. This paper investigates and compares the damage tolerance of scarf and stepped-lap joints (repairs) under quasi-static loading using finite element analysis (FEA). The damage was represented by a flaw embedded in the bondline between composite adherents. 3D FE models were built for both scarf and stepped-lap joints. Both linear and nonlinear adhesive properties were simulated under room temperature (RT) and hot-wet (HW) conditions. The flaws with varying length and width were imbedded in the bondline, so that the sensitivity of damage tolerance to the flaw size can be analysed and compared between scarf and stepped-lap joints. Other parameters, which may affect the damage tolerance of both joints, include flaw location, number of steps of stepped-lap joint, stacking sequence of laminate adherend, out-of-plane boundary conditions and the presence of an external doubler. The results showed that the stepped-lap joint exhibited better damage tolerance than the scarf joint with linear elastic adhesive. The damage tolerance of both joints became similar when the adhesive became nonlinear under RT or HW conditions. The damage tolerance of both joints can be improved by attaching composite doubler reinforcement or constraining the out-of-plane movement.
       
  • A power model to predict the electrical conductivity of CNT reinforced
           nanocomposites by considering interphase, networks and tunneling condition
           
    • Abstract: Publication date: 15 December 2018Source: Composites Part B: Engineering, Volume 155Author(s): Yasser Zare, Kyong Yop Rhee This study develops a power-law model for characterizing the conductivity of polymer carbon nanotube (CNT) nanocomposite by defining the “b” exponent as a function of main parameters such as filler dimensions, filler waviness, interphase thickness, network fraction, tunneling distance, and polymer-filler interfacial energy. Both “b” and conductivity are calculated, and the effects of these parameters on the conductivity are determined. The model accurately predicts the experimentally measured conductivity of the samples. The highest filler conductivity and the lowest “b” exponent cause the maximum conductivity. Some parameters, such as tunneling distance, filler concentration, filler radius, interphase thickness, and waviness, directly affects the “b” exponent, while other parameters, such as the fraction of percolated CNT, interfacial energy, and filler length, demonstrate an inverse relationship with “b.” In addition, short tunneling distance, high filler fraction, thin and large nanotubes, thick interphase, poor waviness, high network fraction, and high interfacial energy produce a high conductivity.
       
  • Evolution of curing residual stresses in composite using multi-scale
           method
    • Abstract: Publication date: 15 December 2018Source: Composites Part B: Engineering, Volume 155Author(s): Zhenyi Yuan, Yongjun Wang, Guigeng Yang, Aofei Tang, Zhenchao Yang, Shujuan Li, Yan Li, Danlong Song Residual stresses occur in composite structures during curing process which play an important role in the deformation and mechanical properties of composite, especially for thick laminates. However, the experimental measurement of curing residual stresses is often costly and complicated. Alternatively, computational tools are used to predict the curing residual stresses. Considering the effect of multi-scale in composites, this paper proposes a multi-scale model to predict the residual stresses of composites during the curing process. At the part level, a macro-scale three-dimensional model, which incorporated the thermo-chemical model and residual stress model, is developed by considering the time-dependent properties of material performances during curing process. The two sub models are mathematically coupled to solve for the process with variables interactively to obtain part-level temperature, degree of cure gradients and macro curing residual stresses. At the reinforcement level, a representative volume elements (RVE) is employed to calculate the micro-scale residual stresses by using the results of macro-scale simulations. The results show there is a significant difference in the calculation of micro residual stresses by introducing the effect of multi-scale model. Subsequently, the effect of different boundary conditions and fiber arrangement are discussed.
       
  • The effects of delamination deficiencies on compressive mechanical
           properties of reinforced composite skin structures
    • Abstract: Publication date: Available online 11 August 2018Source: Composites Part B: EngineeringAuthor(s): Hanhua Li, Yongtao Yao, Liuyu Guo, Qiuhua Zhang, Bing Wang In this study, the compressive properties and failure mode of reinforced composite skin structures having different delamination deficiencies were investigated systematically. Different kinds of delamination deficiencies were presented at specific locations in the specimens. The compressive mechanical properties of the materials were performed by axial compression testing, and strain distribution in different parts of the specimen and bearing capacity were monitored during the compressing processes. The ultimate compression bearing capacity, the failure mode and the expansion of internal damage were investigated as well. Results showed that the existence of delamination deficiencies have effects on the ultimate loading capacity of the specimens in different degree, in which the influence of delamination deficiencies in the skin is the most serious. Comparing with the specimen without deficiencies, the ultimate load-carrying capacity of the specimen with delamination deficiencies in the skin and in the stiffener under compressive load reduced by 38.58% and 22.34%, respectively. The failure modes of specimens with and without delamination deficiencies are similar. Compression failure is the main form of the stiffener, and the skin having different degree of buckling and delamination.
       
  • Phytic acid assisted fabrication of graphene/polyaniline composite
           hydrogels for high-capacitance supercapacitors
    • Abstract: Publication date: Available online 11 August 2018Source: Composites Part B: EngineeringAuthor(s): Jiawen Ji, Ran Li, Huiyu Li, Yang Shu, Yang Li, Shengqiang Qiu, Chengen He, Yingkui Yang Graphene/polyaniline composites were fabricated by an in-situ chemical oxidative polymerization of aniline in the presence of graphene oxide with the assistance of phytic acid. Here graphene sheets construct large conjugated frameworks for anchoring polyaniline through electrostatic, hydrogen bonding, and π-π interactions. Meanwhile, phytic acid functions as the protonation agent for doping polyaniline and also the physical crosslinker for bridging polyaniline chains. Such synergistic effects result in the formation of graphene/polyaniline composite hydrogels. The as-fabricated hydrogels were then used as the additive-free supercapacitor electrodes, which deliver specific capacitances as high as 1217.2 F/g at the scan rate of 10 mV/s, and 865.6 F/g at the current density of 1 A/g in an aqueous electrolyte of 1 M H2SO4, respectively. The initial capacitance remains 78.3% upon increasing to 10 A/g of the current density and retains 82% after charging/discharging 1000 cycles. Such high specific capacitance, good rate capability, and excellent cycling stability are due to the synergistic effect of bifunctional phytic acid and conductive graphene sheets. This work may offer an alternative strategy to produce composite hydrogels for the development of high-performance supercapacitors.
       
  • Preparation and characterization of bioinspired three-dimensional
           architecture of zirconia on ceramic surface
    • Abstract: Publication date: Available online 11 August 2018Source: Composites Part B: EngineeringAuthor(s): Baoxi Zhang, Mingjiang Xiang, Qiang Zhang, Qi Zhang Inspired by bioinspired coating with nanostructures, a heterogeneous zirconia (ZrO2) ceramic membrane has been extensively aspired for changing its intrinsic surface properties. Hence, synthesizing specific nano-microscale architectures of ZrO2 has achieved great interest due to its novel surface properties and application. Here we reported a sol-gel strategy that involved the organic of P123, Brij@C10 and inorganic of Zr-precursor. Impressively, the heterogeneously growth demonstrated that an ultrathin buffer layer could be utilized as the rational mediation of thermal expansion mismatches between their heterogeneously interfaces. This work will raise the potential of bioinspired membrane for emerging applications in industrial processes, such as surface adhesion.
       
  • Flat prestressed unbonded retrofit system for strengthening of existing
           metallic I-Girders
    • Abstract: Publication date: Available online 10 August 2018Source: Composites Part B: EngineeringAuthor(s): Ardalan Hosseini, Elyas Ghafoori, Masoud Motavalli, Alain Nussbaumer, Xiao-Ling Zhao, Riadh Al-Mahaidi In this study, a novel retrofitting system is developed to strengthen existing metallic I-girders using prestressed unbonded carbon fiber reinforced polymer (CFRP) plates. The system relies on a pair of mechanical clamps. Each clamp holds two CFRP plates (each having cross-sectional dimensions of 50 × 1.4 mm) and anchors their prestressing forces to a metallic I-girder via friction. A finite element (FE) model was established to optimize the design of the required mechanical components, and a set of pull-off tests was performed to evaluate the capacity of the optimized system. The proposed flat prestressed unbonded retrofit (FPUR) system was then applied on a 6.4-m-long steel I-beam, and the excellent performance of the system, in terms of stress reduction in the beam bottom flange, was confirmed based on the results of a set of static four-point bending tests. Moreover, a fatigue four-point bending test was conducted on the steel I-beam, strengthened using the proposed FPUR system with a prestressing level of 53% (i.e., approximately 1120 MPa prestress in the CFRPs). Experimental results of the high-cycle fatigue test confirmed the excellent fatigue performance of the proposed FPUR system, as no prestress loss was observed after 20 million fatigue cycles. An analytical model is proposed to accurately predict the stress state in an I-girder strengthened with the proposed FPUR system, while design recommendations are provided concerning the practical use of the system. Relying on the laboratory experimental test results, the proposed FPUR system was used to strengthen the metallic cross-girders of a 121-year-old bridge in Australia.
       
  • Advanced carbon fibre composites via poly methacrylic acid surface
           treatment; surface analysis and mechanical properties investigation
    • Abstract: Publication date: Available online 10 August 2018Source: Composites Part B: EngineeringAuthor(s): Dionisis Semitekolos, Panagiotis Kainourgios, Craig Jones, Amit Rana, Elias P. Koumoulos, Costas A. Charitidis In the present study the enhancement of fibre-matrix interfacial strength in carbon fibre composites was investigated via the electro-polymerization of poly methacrylic acid on commercially available carbon fibre fabrics. The surface modification of the fabrics was examined by means of Infrared (IR) and X-Ray photoelectron (XPS) spectroscopy whereas the surface morphology was studied via Scanning Electron Microscopy (SEM) and Atomic Force Microscopy(AFM). The wetting properties of the modified carbon fibres were investigated via contact angle measurements in single fibre and bundle specimens. For the mechanical performance assessment carbon fibre reinforced polymers (CFRPs) were prepared, via the vacuum resin infusion technique, using both modified and pristine fabrics and subsequently tested via macro scale mechanical testing. All modified composite specimens exhibited increased mechanical performance whereas the most optimum result was reported in Interlaminar Shear Strength (ILSS).
       
  • Microwave absorption and mechanical properties of cross-scale SiC
           composites
    • Abstract: Publication date: Available online 10 August 2018Source: Composites Part B: EngineeringAuthor(s): Qiong Wu, Hanjun Gao, Yidu Zhang, Weijia Shui SiCp/PVDF composite films with cross-scale SiC particle sizes (40 nm and 5, 10, 14, and 28 μm) and five different mass fractions for each particle size (10%, 20%, 30%, 40%, and 50%) were prepared in the present study, and their characteristics, adsorption properties, and mechanical properties were investigated. FE models were also established to study the mechanical properties of the composites further. The results showed that: 1) the SiCp/PVDF composites have good absorption properties over a wide bandwidth, and reflection loss increases with decreasing particle size; 2) the elastic modulus (E) of the films first increases and then decreases with the SiC mass fraction; 3) E decreases with the particle size when the mass fraction ranges from 10% to 20% and first increases and then decreases with the particle size when the mass fraction ranges from 30% to 50%; and 4) the maximum E of the prepared composites is 933 MPa, which is 3.6 times that of conventional PVDF films.Graphical abstractImage 1
       
  • The in situ laser-induced synthesis of the sensor-active microcomposites
           based on molybdenum and its oxides
    • Abstract: Publication date: Available online 9 August 2018Source: Composites Part B: EngineeringAuthor(s): Valeriia E. Baranauskaite, Maxim O. Novomlinskii, Ilya I. Tumkin, Evgeniia M. Khairullina, Andrey S. Mereshchenko, Irina A. Balova, Maxim S. Panov, Vladimir A. Kochemirovsky In the current paper, the in situ laser-induced synthesis of the sensor-active microcomposites based on molybdenum and its oxides has discussed. The influence of pH of the solutions used for deposition and the optical characteristics of the dielectric substrate on the electrical conductivity and the sensor properties of the synthesized deposits has studied. It was shown that the phase distribution in the synthesized materials is consistent with the temperature level in the thermal zones of the laser beam focused on the surface of a dielectric substrate of different type. In turn, highly developed surface area of the obtained deposits is directly responsible for their high sensitivity, short response time, and low temperature of regeneration with respect to hydrogen sulfide and ammonia. Indeed, the highest sensitivity was observed for detection of small concentration (≤50 ppm) of hydrogen sulfide at temperatures of 300–350 °C, whereas at temperatures of 300 °C or less the deposited structures are applicable for the ammonia sensing. The results obtained in this work demonstrate that the method of laser-induced metal deposition is a promising and perspective approach for fabrication of new effective standalone micro-sized gas sensors.Graphical abstractImage 1
       
  • The effect of delamination size and location to buckling behavior of
           composite materials
    • Abstract: Publication date: Available online 9 August 2018Source: Composites Part B: EngineeringAuthor(s): Galip İpek, Yusuf Arman, Abdullah Çelik In this study, the size and location of delamination effects to layered composites' mechanical properties in buckling behavior are inspected experimentally. Composite plates were produced in accordance with the different dimensions of delaminations and the positions between the layers. These plates consist in delamination rates of a/L=0.3,0.5,0.7 (a: Delamination width and L: Buckling length). The specimens were subjected to buckling tests with placed on its two edges, while the others are free. In the experiments two results are considered. First, we determined load-displacement graphs. Critical buckling loads (Pcr) were determined from the obtained load-displacement graphs. Second, we acquire lateral displacements, which occurred with the effect of applied load in the delamination area in direction of plate thickness. By comparing Pcr with each other, an optimum delamination dimension was determined for composite materials with delamination zones. In the applications, the negative effect on the mechanical properties due to delaminations can be seen, proportionally according to the delamination location.
       
  • Multi-scale digital image correlation for detection and quantification of
           matrix cracks in carbon fiber composite laminates in the absence and
           presence of voids controlled by the cure cycle
    • Abstract: Publication date: 1 December 2018Source: Composites Part B: Engineering, Volume 154Author(s): Mahoor Mehdikhani, Eline Steensels, Axelle Standaert, Katleen A.M. Vallons, Larissa Gorbatikh, Stepan V. Lomov Digital image correlation is applied to the images of a deforming composite to obtain strain maps at three length scales: micro-scale (ply level, hundreds of micrometers), meso-scale (laminate level, millimeters), and macro-scale (specimen level, tens of millimeters). The images are acquired in-situ with optical cameras and an electron microscope. The strain mapping at the macro- and meso-scales allows semi-automatic detection of matrix cracks and quantification of their density evolution in function of the applied strain. The micro-scale examination provides additional insights into the failure mechanisms. The technique is developed and then applied to characterize transverse cracking in cross-ply carbon fiber/epoxy composites in the absence and presence of manufacturing defects (including voids). Laminates with defects were produced by lowering the autoclave pressure and the cure temperature, intentionally. The strain for cracking onset and the saturation crack density are found to be different in the inner and outer transverse plies of both types of laminates. The change in processing conditions that led to the presence of voids and incomplete matrix cure resulted in a lower strain for cracking onset and up to 3.5 times increase of the crack density in comparison with the reference material without defects.
       
  • Numerical study on the flexural capacity of ultra-light composite timber
           sandwich panels
    • Abstract: Publication date: Available online 8 August 2018Source: Composites Part B: EngineeringAuthor(s): Siavash Darzi, Hassan Karampour, Benoit P. Gilbert, Henri Bailleres The flexural stiffness and ultimate load capacity of novel ultralight composite sandwich panels, made of plywood faces and bamboo or peeling cores are investigated herein. Modified Ritz method and sandwich beam theory formulations for composite sandwich panels with thick faces and thick/stiff cores are developed, and are used to find the bending stiffness of the panels in one-way and two-way bending. The ultimate capacity and failure modes of the panels are then predicted from nonlinear material and geometric finite element analyses (FEA). The numerical methods are validated against published experimental results of orthotropic composite sandwich panels. It is shown that at similar panel depths, the proposed composite timber panels can be as high as 15% stiffer and 40% lighter than the existing commercial cross-laminated timber (CLT) panels. Results of a parametric study on selected composite panels with different yield stresses in compression, show that panels with bamboo cores exhibit relatively more ductile behaviour compared to those with peeling cores. At the ultimate flexural capacity, the tensile face of the panels fails in tension parallel to the grain, while the compressive face almost reaches its yield capacity.
       
  • Factors affecting barrier performance of composite anti-corrosion coatings
           prepared by using electrochemically exfoliated few-layer graphene as
           filler
    • Abstract: Publication date: Available online 8 August 2018Source: Composites Part B: EngineeringAuthor(s): Sneha Daradmare, Sunny Raj, Arup R. Bhattacharyya, Smrutiranjan Parida The electro-exfoliated few-layer graphene (FLG) sheet and epoxy composite systems were studied as model composite coatings. Increasing the loading up to 1 wt% increased the corrosion resistance of the coating by ∼20 times, hardness by 30%, elastic modulus by 35% as compared to neat epoxy coating. At a fixed FLG loading, the above mentioned parameters strongly varied with the homogenization time. The mean ‘agglomerates’ size of FLG in the composite coating decreased from 17.4 μm to 10.6 μm for increasing the homogenization from 10 to 60 min. Correspondingly, mechanical properties of the composite coatings decreased and anticorrosion property increased.Graphical abstractImage 1
       
  • In-situ homogeneous growth of ZrC nanowires on carbon cloth and their
           effects on flexural properties of carbon/carbon composites
    • Abstract: Publication date: Available online 7 August 2018Source: Composites Part B: EngineeringAuthor(s): Ningning Yan, Xiaohong Shi, Kun Li, Qiangang Fu, Wei Xie, Hongrui Zhang, Qiang Song In-situ ZrC nanowires (ZrCNWs) has been successfully synthesized on carbon cloth by precursor pyrolysis. The morphology, microstructure and chemical composition of the ZrCNWs were characterized by SEM, TEM, EDS and XRD. The results show that the ZrCNWs are single crystal structures with diameters of approximately 500–1000 nm and an aspect ratio of up to 100. A growth model based on SLS (Solid-Liquid-Solid) mechanism is proposed to explain the growth of ZrCNWs, which reveals that the reason for the formation of ZrCNWs was the auxiliary action of the catalyst. The pyrolytic carbon (PyC) has high texture (HT) whose extinction angle is 18–20° and the growth mode of PyC is cone-shaped in ZrCNWs modified C/C composites. The toughening mechanism in ZrCNWs modified carbon/carbon (C/C) composites can be realized by the bridging of ZrCNWs, cracks deflecting, and the enhancement of interfacial bond strength between matrix and fiber. The flexural strength of C/C composites is increased by 163.2% after the introduction of ZrCNWs.
       
  • Geometrically nonlinear analysis of laminated composite quadrilateral
           plates reinforced with graphene nanoplatelets using the element-free
           IMLS-Ritz method
    • Abstract: Publication date: Available online 7 August 2018Source: Composites Part B: EngineeringAuthor(s): Hulun Guo, Shuqian Cao, Tianzhi Yang, Yushu Chen This paper investigates the nonlinear bending of graphene nanoplatelet (GPL) reinforced laminated composite quadrilateral plates using the element-free IMLS-Ritz method. The effective material properties including Young's modulus, mass density and Poisson's ratio are determined by the modified Halpin-Tsai model and rule of mixture. The first-order shear deformation theory (FSDT) and the IMLS-Ritz approximation are employed to obtain the discrete nonlinear governing equation of quadrilateral plates with large deformation. The Newton-Raphson method is used to solve the nonlinear equation. The accuracy of the IMLS-Ritz results is examined by comparing with the published values. A comprehensive parametric study is carried out, with a particular focus on the effects of geometric parameters of quadrilateral plates and GPLs distribution pattern, weight fraction, total number of layers, and geometry and size of GPLs on the nondimensional deflection of GPLs reinforced laminated composite quadrilateral plate.
       
  • High strain rate effects on mechanical properties of inductively coupled
           plasma treated carbon nanotube reinforced epoxy composites
    • Abstract: Publication date: Available online 7 August 2018Source: Composites Part B: EngineeringAuthor(s): Hana Jung, Hoi Kil Choi, Hun-Su Lee, Yonjig Kim, Jaesang Yu Structures can be loaded statically or dynamically with a wide range of strain rate. With high strain rates, the relationship between stress and strain is not the same as that in static loading. It has been observed that polymer composite properties are dependent upon the strain rate at which they are tested. The most commonly used method for determining the dynamic response of materials is the Split Hopkinson pressure bar, which can test materials at strain rates as high as 1200/s to 4200/s. It is observed that the compressive strength of thermoset epoxy resin increases up to 107% at a high stain rate compared with that at quasi-static loading.This shows strongly sensitive compressive behavior at high strain rates; i.e. the structural properties of the reinforcement and energy absorption capacity are affected at high strain rates. Reinforcing nitrogen doped multi-walled carbon nanotubes (MWCNTs) can effectively improve the compressive strength as well as the strain energy of the epoxy matrix due to their uniform dispersion in the epoxy matrix.
       
  • Cure behaviors of furfuryl alcohol/epoxy/methyltetrahydrophthalic
           anhydride and their enhanced mechanical and anti-acid properties of basalt
           fiber reinforced composites
    • Abstract: Publication date: Available online 7 August 2018Source: Composites Part B: EngineeringAuthor(s): Zhi Wang, Fanbin Meng, Xiangyu Li, Xin Zhang, Weihong Hu, Guizhe Zhao Catalyzing furfuryl alcohol and epoxy simultaneously with a suitable catalyst plays a key role in the preparation of high-performance blends. Herein, methyltetrahydrophthalic anhydride was utilized to cure furfuryl alcohol/epoxy resins, which reacted with epoxy firstly, then catalyzed the furan reaction and also linked furfuryl alcohol and epoxy. Moreover, partly ring-opened furan further catalyzed the curing reaction of epoxy. The addition content of methyltetrahydrophthalic anhydride affected the curing behaviors of furfuryl alcohol/epoxy blends, and their Tg and char yield at 700 °C reached the maxima of 140 °C and 16.79% respectively as the content increased to 50%. The mechanical and anti-acid properties of basalt fiber-reinforced composites were further studied. The mechanical properties of composites changed identically to those of the matrix did. Furfuryl alcohol improved the acid resistance of composites, probably because furan could be cured in acidic condition and basalt fiber was resistant to acid. All these changes were related to the curing mechanism and crosslinking density of furan/epoxy/methyltetrahydrophthalic anhydride blends.
       
  • Steel fiber confined graphite concrete for pavement deicing
    • Abstract: Publication date: Available online 7 August 2018Source: Composites Part B: EngineeringAuthor(s): Rui Rao, Jiyang Fu, Yijen Chan, Christopher Y. Tuan, Chunhui Liu Electric heating concrete is a specialized concrete containing electrically conductive components to attain stable conduction of electricity. Due to its electrical resistance, a thin electric heating concrete overlay can generate heat to prevent ice formation on a concrete roadway when connected to a power source.This electric heating concrete (EHC) deicing technology has been implemented in China at a large scale for the first time. A 3.5-in. (9 cm) thick electric heating concrete layer was cast on the top of two existing parking ramps in Harbin. The East Ramp is 135 feet (41 m) long and 18.5 feet (5.6 m) wide and the North Ramp is 135 feet (41 m) long and 25 feet (7.6 m) wide, both having a steep slope of 15%. The overlay on each parking ramp was divided into 20 blocks.The electric heating concrete overlays were cast in place. Transformers converting 220 V AC to 48 V AC were used for the power source. Steel angle structural shapes were embedded in the electric heating concrete for electrodes. Some electric wires were pulled off from the electrodes during the construction. As a result, the power to a few blocks on each ramp was cut. A hand-held magnetic field meter was used to troubleshoot the disconnection locations. Based on measurements of the magnetic field strengths, all the disconnected wires in the hardened concrete were detected and reattached to the electrodes. The drilled holes were patched with carbon cement paste. Subsequent testing showed that good heating performance was successfully restored.
       
  • Reinforcement of interfacial and bonding strength of soybean meal-based
           adhesive via kenaf fiber–CaCO3 anchored N-cyclohexyl-2-benzothiazole
           sulfenamide
    • Abstract: Publication date: Available online 7 August 2018Source: Composites Part B: EngineeringAuthor(s): Xiaorong Liu, Kaili Wang, Weidong Gu, Feng Li, Jianzhang Li, Shifeng Zhang The development of soybean meal-based adhesive is currently hindered by its weak bonding strength and poor water resistance. This study aims to develop a natural fiber-reinforced soybean meal adhesive with enhanced water resistance and bonding strength. To improve the interfacial interaction between the matrix and kenaf fiber (KF), the fiber was modified using a two-step process, (1) KF was treated with calcium carbonate (TKF) via an inorganic nanoparticle impregnation (INI) process; and (2) N-cyclohexyl-2-benzothiazole sulfenamide (CZ) was chemically bonded onto TKF to obtain the functionalized fiber (TKF-s-CZ). The bonded CZ molecules on TKF were found to have stronger interfacial interaction between TKF-s-CZ and the matrix, accelerating the crosslinking reaction. The resultant PSM/TKF-s-CZ adhesive exhibited higher bonding strength and water-resistance than the control one. Compared to the control one, the wet shear strength of the PSM/TKF-s-CZ adhesive increased from 0.38 MPa to 1.64 MPa, counting for an increase of 331.57%. The moisture uptake was reduced to 8.75% (10.76% of the PSM/TKF adhesive). This work also provides a new design strategy for the surface modification of filler and prepares a renewable, value-added soybean meal-based adhesive, which could play an important role in expanding the industrialized applications of these adhesives.Graphical abstractImage 1
       
  • Direct activation of copper electroplating on conductive composite of
           polythiophene surface-coated with nickel nanoparticles
    • Abstract: Publication date: Available online 7 August 2018Source: Composites Part B: EngineeringAuthor(s): Jiujuan Li, Guoyun Zhou, Xiaofeng Jin, Yan Hong, Wei He, Shouxu Wang, Yuanming Chen, Wenjun Yang, Xinhong Su In this work, a novel method involving conductive polymer and nanoparticles for copper electroplating on insulating substrate is proposed. Nickel nanoparticles is introduced into the network of polythiophene (PT) to form PT-based composite is confirmed to be the essential prerequisite to initiate copper electroplating. It thus realizes the direct metal electroplating on conductive polymers-based composite. Multiple characterizations are conducted to confirm that the nickel nanoparticles act as metal crystal nucleus for copper deposition during the electroplating. The electroplating rate and peel strength are systematically examined to evaluate the practical performances of as-obtained copper on PT-based composite. Experimental results show that the conductive composite of PT surface-coated with nickel nanoparticles (NiNPs) mediated copper layer holds excellent adhesion property in comparison with the one generated through conventional metal deposition method.Graphical abstractImage 1
       
  • Experimental assessment of the mechanical behaviour of 3D woven composite
           T-joints
    • Abstract: Publication date: Available online 4 August 2018Source: Composites Part B: EngineeringAuthor(s): Shibo Yan, Xuesen Zeng, Andrew Long To understand the influence of the fibre architecture of 3D woven composite T-joints on mechanical performance, as well as the benefits that 3D woven T-joints can offer over the equivalent 2D laminates, experimental testing is performed on two types of 3D woven T-joint with only weave variation at the junction, and one type of 2D woven laminate T-joint. A quasi-static tensile pull-off loading is selected in this work as this out-of-plane load case is one of the typical loading conditions for such T-joint structures. The significant advantages of 3D woven composite T-joints in terms of ultimate strength and damage tolerance over the 2D alternative were identified in the testing. More importantly, this work showed that variation in the fibre architecture can considerably enhance properties such as delamination resistance and total energy absorption to failure, as well as increasing slightly the stiffness and initial failure load. This experimental assessment has demonstrated that using 3D woven reinforcements is an effective way to improve the load-bearing capability of composite T-joints over laminates, and also that this improvement could be optimised with regard to fibre architecture.
       
  • Experimental determination of the static and fatigue strength of the
           adhesive joints bonded by epoxy adhesive including different particles
    • Abstract: Publication date: Available online 4 August 2018Source: Composites Part B: EngineeringAuthor(s): İsmail Saraç, Hamit Adin, Şemsettin Temiz Because of their many advantages, adhesively bonded joints are intensively used in many engineering fields. So, the mechanical research of the adhesively bonded joints is very important to use these joints safely. There are many studies performed by researchers to investigate the mechanical properties of the adhesive joints. There has been a considerable interest in nanoparticles added to structural adhesives recently because nanoparticles improve the mechanical properties of adhesives and joints. In this paper, different nanoparticles reinforced by epoxy adhesive, and neat adhesive were used to produce single lap joints. The static and fatigue strengths of single lap joints incorporating nanoparticles were compared to those without nanoparticles. Experiments were performed at 20 mm overlap length. DP460 epoxy was used as the adhesive material, and nano-Al2O3, nano-TiO2 and nano-SiO2 were used as the nanoparticles; and AISI 304 stainless steel plates were used as the adherents. The results of the experimental research revealed that average failure load increased significantly in nanoparticle-reinforced adhesive joints. The highest average failure load was obtained with 4 wt% nano-Al2O3 in epoxy adhesive. Fatigue tests were performed at 10 Hz frequency, and 0.1 loading ratio (R). When the fatigue test results were examined, it was observed that the addition of the nano-Al2O3 and nano-SiO2 to the adhesive increased fatigue strength of the adhesive joints, on the other hand, the addition of the nano-TiO2 to the adhesive reduced fatigue strength of the adhesive joints.Graphical abstractImage 1
       
  • CNT-polymer nanocomposites under frictional contact conditions
    • Abstract: Publication date: Available online 4 August 2018Source: Composites Part B: EngineeringAuthor(s): Luis Rodríguez-Tembleque, Enrique García-Macías, Andrés Sáez The unique intrinsic physical properties of Carbon NanoTubes (CNTs) suggest that they are ideal fillers for high-performance composites. Although some experimental studies have revealed the potential of these nanoparticles to tailor the tribological properties of polymer-based composites, the number of theoretical studies on the characterization of their frictional behavior is still very low. This paper is aimed at filling this lacuna by addressing the theoretical analysis of the indentation response of CNT-polymer nanocomposites. To do so, it is first necessary to compute the overall mechanical properties of CNT-polymer composites. Secondly, these properties must be used to evaluate the macroscopic indentation response of the composites. In this work, an extended Mori-Tanaka approach is used to extract the constitutive properties of CNT-polymer nanocomposites. On the basis of ad hoc Eshelby's tensors accounting for particular wavy filler geometries, along with a two-parameter agglomeration model, the homogenization process is performed considering the coupled effect of fillers' waviness and agglomeration. Afterward, a 3D boundary element formulation for contact modeling is applied to study the indentation response of these nanocomposites. The main objective of this paper focuses on analysing the influence of micromechanical features such as fiber content, orientation, waviness, and dispersion on the indentation response of CNT-polymer nanocomposites. Detailed parametric analyses are presented to characterize this phenomenon under frictional contact conditions. The numerical results demonstrate that fillers' waviness and agglomeration have a coupled detrimental effect on the macroscopic response of CNT-reinforced composites.
       
  • Structural laminated hybrid composites based on raffia and glass fibers:
           Effect of alkali treatment, mechanical and thermal properties
    • Abstract: Publication date: Available online 3 August 2018Source: Composites Part B: EngineeringAuthor(s): Wafa Ouarhim, Hamid Essabir, Mohammed-Ouadi Bensalah, Nadia Zari, Rachid Bouhfid, Abou el kacem Qaiss This work deals with the effect of the alkaline treatment of laminated hybrid composite materials based on Rafia fibers and glass fibers in sandwich structure. Structural analysis (Fourier Transform Infrared Spectroscopy) has shown that most of the changes caused by the alkaline treatment of Rafia fibers involve the removal of fiber surface from a certain amount of wax, hemicellulose, pectin and lignin. These changes are at the origin of the improvement of the mechanical properties of the composites. Flexural modulus results show an increase of 3.4 GPa–3.6 GPa for the untreated and treated Rafia fiber sandwich composites, respectively. The degree of interfacial adhesion quantified by a droplet test, shows that the alkaline modification reveals a sharp increase in shear stress for processed Rafia fibers with a 38% gain compared to untreated fibers. In addition, the measurement of the thermal conductivity has proved that the alkaline treatment decreases the thermal conductivity of the fibers. Finally, the mixing rule technique was used to predict the flexural modulus of the laminates using the mechanical parameters of each layer and the result was compared to the experimental data. It is assumed that Rafia fiber treatments will support the development of synthetic fiber reinforced sandwich polymer composites for industrial applications.
       
  • Experimental mechanical characterization of composite-concrete joints
    • Abstract: Publication date: Available online 3 August 2018Source: Composites Part B: EngineeringAuthor(s): J. Justo, F. París The use of composite materials as a reinforcement for concrete in civil construction has become a significant topic, the quality of the joint between composite and concrete being one of the key parameters to study. The preparation of surfaces involved in the joint and the fabrication procedure are relevant factors in this quality. Two surface treatments of concrete (grinder and grit sandpaper) and three manufacturing techniques of the composite and corresponding joining to the concrete (precured composite, wet hand lay-up and infusion) have been employed. To evaluate the quality of the joint, four tests have been applied: Lap peeling, Lap shear, Pull off and Shear torsion. Once the tests were carried out, all of them were found representative of the quality of the joint and it was observed that concrete cracking predominates over adhesive or cohesive failures, which indicates a satisfactory adhesion between the concrete and the composite. Grinder surface treatment was found the best option, and with reference to the manufacturing technique, the use of pre-fabricated reinforcement was found to lead to undervalues of the properties.
       
  • New evaluation of interfacial properties and damage sensing in CFRC by
           VARTM using 3D ER mapping
    • Abstract: Publication date: Available online 3 August 2018Source: Composites Part B: EngineeringAuthor(s): Jong-Hyun Kim, Dong-Jun Kwon, Pyeong-Su Shin, Yeong-Min Baek, Ha-Seung Park, K. Lawrence DeVries, Joung-Man Park Currently carbon fiber reinforced composites (CFRC) are commonly used in application in which the manufacturing of holes is necessary. In the research reported here CFRC plates were manufactured using two different resins, epoxy and unsaturated polyester (UP), by a vacuum assisted resin transfer molding (VARTM) process. The permeability, as indicated by the spreading difference via VARTM, was measured for two composites with the same fiber volume fraction but different viscosities. The interfacial properties of the CFRC, manufactured using these different resins, were evaluated utilizing the interlinear shear strength (ILSS) test and contact angle measurements. Three dimensional electrical resistance (3D ER) mapping was used to detect damage caused by the drilling of holes in the CFRC plates. Typically such drilling results in damage such as delamination, for which the location and extent of damage of was determined using 3D ER mapping. It was determined that the carbon fiber/UP composite experienced more damage during drilling than the carbon fiber/epoxy composite. This research illustrated the utility of 3D ER mapping for successfully detecting damage in composites and its potential for use in various other practical applications.
       
  • The effect of tension compression asymmetry on modelling the bending
           response of sheet moulding compound composites
    • Abstract: Publication date: Available online 3 August 2018Source: Composites Part B: EngineeringAuthor(s): Jonathan Tham, Trevor Sabiston, Anna Trauth, Julie Lévesque, Kay André Weidenmann, Kaan Inal Phenomenological models are required to predict the behaviour of a glass fibre reinforced Sheet Moulding Compound (SMC) composite material for use in the automotive industry. Material testing is conducted in tension, compression, in-plane shear, and three-point bending. The SMC composite exhibits tension-compression asymmetry and in-plane anisotropy. A model, which incorporates an anisotropic and asymmetric yield function, is developed. The model is calibrated to the experimental tension, compression and in-plane shear tests and are validated using the three-point flexure test. The model captures the flexure response within 8.1% of the experimental observations. The importance of including tension compression asymmetry within the model is demonstrated.
       
  • Silver/poly(vinyl alcohol)/chitosan/graphene hydrogels – Synthesis,
           biological and physicochemical properties and silver release kinetics
    • Abstract: Publication date: Available online 3 August 2018Source: Composites Part B: EngineeringAuthor(s): Katarina Nešović, Ana Janković, Vesna Kojić, Maja Vukašinović-Sekulić, Aleksandra Perić-Grujić, Kyong Yop Rhee, Vesna Mišković-Stanković This study presents the synthesis of novel silver/poly(vinyl alcohol)/chitosan/graphene (Ag/PVA/CHI/Gr) nanocomposite hydrogels by in situ electrochemical reduction of silver ions in the hydrogel matrix and their thorough characterization by UV-visible and Raman spectroscopies, field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and silver release measurements. The influence of chitosan content on the incorporation and stabilization of silver nanoparticles (AgNPs) was investigated, and we found that hydrogels with higher chitosan content contain higher amounts of AgNPs. In addition, the cytotoxicity and antibacterial activity of Ag/PVA/CHI/Gr nanocomposite hydrogels were evaluated. Based on in vitro investigations, the obtained materials exhibit diffusion-controlled release profiles over 28 days, strong antibacterial activity against Staphylococcus aureus and Escherichia coli bacterial strains, and no cytotoxicity toward human and mice fibroblast cell lines.Graphical abstractImage 1
       
  • Mimicking nature: Fabrication of 3D anisotropic electrospun
           polycaprolactone scaffolds for cartilage tissue engineering applications
    • Abstract: Publication date: Available online 3 August 2018Source: Composites Part B: EngineeringAuthor(s): André F. Girão, Ângela Semitela, Gonçalo Ramalho, António Completo, Paula A.A.P. Marques There is a growing need to develop strategies capable of engineering the anisotropic cartilaginous fibrous network in vitro and consequently overcome the anatomical and functional restrictions of the standard medical procedures used for cartilage regeneration. In this work, we suggest a fabrication procedure to build 3D anisotropic multi-layered fibrous scaffolds. Polycaprolactone (PCL) was used as bulk material for the different electrospun layers (horizontally, randomly and vertically aligned) that were assembled and then structurally maintained by a biocompatible graphene-oxide-collagen (GO-collagen) microporous network. To validate the resourcefulness of the technique, four PCL-GO-collagen scaffolds with different anisotropic properties were produced and characterized by analysing their depth dependent morphological and mechanical properties.Graphical abstractImage 1
       
  • High corrosion resistance performance of 304 stainless steel after liquid
           nitrocarburization
    • Abstract: Publication date: Available online 2 August 2018Source: Composites Part B: EngineeringAuthor(s): Han Zhao, Lian Duan, Guang Chen, Hongyuan Fan, Jun Wang, Changchun Zhou 304 stainless steel is widely used in many industrial fields, however, poor wear resistance of H2S limited its applications. In this study, novel composites coatings were deposited onto stainless steel surface by a liquid nitrocarburization technique. XRD, EMPA, SEM were conducted to investigate the surface modification of 304 Austenitic Stainless Steel after liquid nitrocarburization for 8 h at 703 K (430 °C). Wear test results showed that the wear resistance of nitrocarburized 304 stainless steel was increased in comparison with the non-nitrocarburized one. The corrosion potential was investigated by standard saturated hydrogen sulfide gas. And the results indicated that the austenite transformed into the S phase after forming supersaturated solid solution of N on the surface and kept intact after corrosion test. The corrosion current density was clearly reduced. Low diffusion coefficient of hydrogen atoms in S-phase reduced the possibility of environmental cracking of H2S and improved the H2S corrosion resistance of after liquid nitrocarburization.
       
  • The evolution of anti-vortex like domain under electric field in
           polycrystalline ferroelectric
    • Abstract: Publication date: Available online 1 August 2018Source: Composites Part B: EngineeringAuthor(s): Xiaobao Tian, Changchun Zhou, Xiaoqiao He, Zhihong Zhou, Yu Chen, Hao Guo, Haidong Fan Domain wall (DW) plays an important role in the domain evolution. The anti-vortex could be a special domain structure of the mixed DWs, i.e. the Ising wall and the Mixed Ising-Neel wall. The anti-vortex domain in polycrystalline ferroelectric has been investigated by a modified first-principles-based atomistic method incorporating the anisotropic shell model. Results show that the nucleation and the disappearance of the anti-vortex happen at grain boundaries (GBs) under sinusoidal electric fields loading. As the anti-vortex motion by the electric field, it is a perfect view point for the domain evolutions. It has been found that the anti-vortex core can't pass through the GBs because of the size and disorder field. This phenomenon indicated that anti-vortex is only been obtained in grains at polycrystalline ferroelectric, and the electric field range must between −6.3 and 6.3 × 108 V/m.
       
  • Analysis of multilayered structures embedding viscoelastic layers by
           higher-order, and zig-zag plate elements
    • Abstract: Publication date: Available online 1 August 2018Source: Composites Part B: EngineeringAuthor(s): M. Filippi, E. Carrera, S. Valvano In this work, a number of higher-order plate elements and an improved theory based on a zig-zag power function have been applied to metallic and composite layered structures with viscoelastic layers. The kinematic field is written by using an arbitrary number of continuous piecewise polynomial functions. The polynomial expansion order of a generic subdomain is a combination of zig-zag power functions depending on the plate thickness coordinate. Damped free-vibrations and frequency response analysis are performed modelling the viscoelastic properties with the complex modulus approach, and taking into account different damping laws for the viscoelastic layers included a five-parameter fractional-derivative model. The governing equations are derived from the Principle of Virtual Displacements and solved using the Finite Element (FE) method, and both full and reduced-order formulation are taken into account. Furthermore, the Mixed Interpolated Tensorial Components (MITC) method is employed to contrast the shear locking phenomenon. The Carrera Unified Formulation (CUF) has been employed to derive the governing FE equations for the various theories considered in this paper in an unified form. Several numerical investigations are carried out to validate and demonstrate the accuracy and efficiency of the present plate element. The results are reported in terms of frequencies, modal loss factors and frequency responses, and they are compared with solutions published in the literature and with solid finite element models.
       
  • Toward improved performances of para-aramid (PPTA) paper-based
           nanomaterials via aramid nanofibers(ANFs) and ANFs-film
    • Abstract: Publication date: Available online 1 August 2018Source: Composites Part B: EngineeringAuthor(s): Bin Yang, Meiyun Zhang, Zhaoqing Lu, JingJing Luo, Shunxi Song, Jiaojun Tan, Qiuyu Zhang Para-aramid (PPTA) paper serves as the promising candidates for the heat-resistance insulating material and lightened-weight structure component due to its impressive mechanical property, inherent dielectric strength and thermal durability. However, the chemical inertness and the smooth surface of PPTA fibers lead to poor interfacial adhesion and inferior quality of PPTA paper. Here, for the first time, a facile and promising strategy to significantly improve the performances of the PPTA paper via incorporating the aramid nanofibers (ANFs) or laminating with the ANFs-film is proposed. The microstructures, mechanical properties, dielectric strength and reinforcing mechanisms of the resultant PPTA papers were investigated. PPTA paper with 6.0 wt% ANFs shows improved ultimate strength and dielectric strength (145.1% and 44.1% increases, respectively) than the pristine PPTA paper due to the interfacial bonding improvement of the ANFs serve as the bridging binders, fillers, inlaying nails and self-assembly films. Moreover, the adhesive-free ANFs-films laminated PPTA papers with tailored structures also exhibit remarkable mechanical and dielectric strength. The results indicate the great potential of ANFs or ANFs-film as a new class of reinforcements for PPTA paper, and also paves a promising way to fabricate high-performance paper-based nanomaterials, such as insulating materials and flexible display materials, etc.Graphical abstractImage 1
       
  • Higher performance carbon fiber reinforced thermoplastic composites from
           thermoplastic prepreg technique: Heat and moisture effect
    • Abstract: Publication date: Available online 1 August 2018Source: Composites Part B: EngineeringAuthor(s): Yan Ma, Shanshan Jin, Masahito Ueda, Tomohiro Yokozeki, Yuqiu Yang, Fumitake Kobayashi, Hiroaki Kobayashi, Toshi Sugahara, Hiroyuki Hamada In this study, higher performance unidirectional carbon fiber reinforced polyamide-6 composites were manufactured from prepreg by using hot compression methods with assistance of spread tow technology. UD CF/PA6 laminates with uniform fiber distribution and in good impregnation are achieved. Various mechanical properties of UD CF/PA6 laminates were evaluated by using tensile tests and three-point tests. The effects of heat and moisture on the flexural properties of UD CF/PA6 laminates were carried out through hot air exposure and hot water immersion process at different temperature for different time, respectively. The corresponding effects on the neat resin were also investigated to verify the role of matrix degradation by three-point bending tests and fourier transform infrared spectroscopy analysis. The optical microscopy and scanning electron microscopy observation were carried out to investigate the fracture behaviors and explain the fracture mechanism. Results indicated that no obvious negative effect of heat (
       
  • Thermal stability and ablation resistance, and ablation mechanism of
           carbon–phenolic composites with different zirconium silicide particle
           loadings
    • Abstract: Publication date: Available online 31 July 2018Source: Composites Part B: EngineeringAuthor(s): Jie Ding, Tao Yang, Zhixiong Huang, Yan Qin, Yanbing Wang ZrSi2 modified carbon–phenolic (C-Ph) composites are prepared using different weight loadings of zirconium silicide particle by compression moulding. The thermal stability and ablation resistance of composites are investigated by thermal gravimetric analysis (TGA) and oxyacetylene torch test. Moreover, the phase composition and microstructure of ablated surface are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). The results show that introduced ZrSi2 particles result in an evident increase in the residual weights of C–Ph composites at high temperatures, and the enhancement in thermal stability under air atmosphere exhibits positive effects on improving the ablation resistance of C-Ph composites. The optimum ZrSi2 weight loading for the improvement of ablation resistance in C-Ph composites is 5wt%. The linear and mass ablation rates of composites after modifying with 5wt% ZrSi2 particles are reduced by 80.5% and 55.2%, respectively. This work provides an effective way to prominently improve the ablation performance of C–Ph composites, and it maybe become a backbone of thermal protection system in aerospace.
       
  • Bending and free vibration of multilayered functionally graded doubly
           curved shells by an improved layerwise theory
    • Abstract: Publication date: Available online 31 July 2018Source: Composites Part B: EngineeringAuthor(s): M.E. Fares, M. Kh Elmarghany, Doaa Atta, M.G. Salem An improved layerwise theory is established for the bending and vibration responses of multi-layered functionally graded doubly curved shells with material properties varying gradually and continuously across the whole shell thickness. The theory accounts for shear deformation and normal strain effects by assuming for each layer, a displacement field with zigzag first-order in-plane displacements and through-the-thickness parabolic transverse displacement. Moreover, it is assumed a stress field satisfying the loading conditions on the external shell faces and the continuity conditions of the internal stresses at the layers interfaces, so, there is no need for introducing in the present formulation any shear correction factor. For this purpose, a mixed variational statement is used. The continuity conditions for the displacements at the layers interfaces are used to decrease the degrees of freedom of the theory. Bending and free vibration problems are solved for FGM single- and three-layered sandwich open cylindrical and spherical shells with completely simply supported or clamped edges. Comparisons for some present results with numerical results obtained by other authors due to advanced 2D and 3D elasticity solutions are made showing the high efficiency of the present theory in predicting the bending and vibration parameters. Graphics are presented to demonstrate the importance of the normal strain effect for the static bending and free vibration of the considered shells.
       
  • Polydopamine induced natural fiber surface functionalization: A way toward
           flame retardancy of Flax/Poly(lactic acid) biocomposites
    • Abstract: Publication date: Available online 29 July 2018Source: Composites Part B: EngineeringAuthor(s): Lu Zhang, Zhi Li, Ye-Tang Pan, Adriana Pérez Yáñez, Shuang Hu, Xiu-Qin Zhang, Rui Wang, De-Yi Wang Aiming to improve flame retardancy of natural fiber reinforced poly (lactic acid) (PLA) composites, a bio-inspired fiber surface modification approach was investigated in this study. Raw flax fiber was firstly coated with a thin adhesive polydopamine (PDA) film in an aqueous solution of dopamine, followed by in situ growth of iron phosphonate on the fiber surface. The modified flax fiber was added into PLA to prepare flame retardant biocomposite. Compared with raw flax reinforced PLA with a limiting oxygen index (LOI) of 19.1% and no rating in vertical burning test (UL-94), the modified PLA composite possessed a high LOI of 26.1% and V-2 rating. Meanwhile, the fiber surface modification resulted in suppression on both peak heat release rate (decreased by 16%) and total smoke production (decreased by 21%) in cone calorimeter test (CCT). Moreover, tensile modulus of the flame retardant composite was remarkably enhanced, accompanied with a slightly decreased tensile strength compared to raw PLA. The polydopamine assisted surface modification proved to be a feasible approach to improve the flame retardancy of fiber reinforced composites.Graphical abstractImage 1
       
  • Decoupled stability equation for buckling analysis of FG and multilayered
           cylindrical shells based on the first-order shear deformation theory
    • Abstract: Publication date: Available online 27 July 2018Source: Composites Part B: EngineeringAuthor(s): Famida Fallah, Ehsan Taati, Mohsen Asghari Based on the first-order shear deformation and Donnell's shell theory with von Karman non-linearity, one decoupled stability equation for buckling analysis of functionally graded (FG) and multilayered cylindrical shells with transversely isotropic layers subjected to various cases of combined thermo-mechanical loadings is developed. To this end, the equilibrium equations are uncoupled in terms of the transverse deflection, the force function and a new potential function. Using the adjacent equilibrium method, one decoupled stability equation which is an eighth-order differential equation in terms of transverse deflection is obtained and conveniently solved to present analytical expressions for buckling loads of cylindrical shells under any type of loading. These analytical expressions can be used in design and as a benchmark in numerical studies. For numerical purpose, the formulation is applied to FG shells, a three-layer shell laminated of transversely isotropic layers, and sandwich shells with an isogrid lattice core and transversely isotropic face sheets. The results are validated with the existing ones in the literature. Finally, the effect of different parameters on the buckling loads in the presence of combined loadings is discussed in detail. Numerical results show that the existence of an initial hoop stress as a main type of initial imperfection has significant influence on the buckling behavior (including buckling values and mode shapes) of long cylindrical shells subjected to axial loading and this effect reduces for cylindrical shells with a lattice core. Furthermore, the critical values of torsion significantly reduce under combined loading.
       
  • Effect of transverse strains and angular distortions on the nanoscale
           elastic behavior of platelet nanocomposites
    • Abstract: Publication date: Available online 27 July 2018Source: Composites Part B: EngineeringAuthor(s): G. Fernández Zapico, J.M. Muñoz Guijosa, Benito del Río, Hiroki Akasaka In order to correctly predict the macroscale elastic behavior of nanocomposite macroscale structures, an accurate nanoscale model must be available for subsequent homogenization. In this work, we demonstrate that the accuracy of that nanoscale model greatly depends on the consideration of transverse strains and angular distortions, which are not frequently taken into account, but have a significant influence on the cohesive mechanisms at the nanofiller-matrix interface. We use a nanoscale cohesive model to qualitatively and quantitatively analyze the effect of transverse shear and angular distortion on the interfacial stress transfer mechanisms. While the effect of the transverse strain is less significant, results show that angular distortion greatly affects the interfacial damage pattern. It appears to shift the interfacial shear stress distribution to one of the interface ends, which consequently also modifies the interfacial longitudinal stress distribution and its mean value, resulting in reduced nanocomposite stiffnesses. The effect should be taken into account as shear and transverse strains may be present at the macroscale if, for instance, nanofiller misalignment or stress concentrators exist. We also provide design maps representing damage onset for different 2D multiaxial strain states in graphene-epoxy nanocomposites, so that the strain state limit can be inferred for the given nanocomposite properties. A substantial reduction in the allowable strains can be observed.
       
  • Effect of delamination on the stochastic natural frequencies of composite
           laminates
    • Abstract: Publication date: Available online 26 July 2018Source: Composites Part B: EngineeringAuthor(s): T. Mukhopadhyay, S. Naskar, P.K. Karsh, S. Dey, Z. You The coupled effect of manufacturing uncertainty and a critical service-life damage condition (delamination) is investigated on the natural frequencies of laminated composite plates. In general, delamination is an unavoidable phenomenon in composite materials encountered often in real-life operating conditions. We have focused on the characterization of dynamic responses of composite plates considering source-uncertainty in the material and geometric properties along with various single and multiple delamination scenarios. A hybrid high dimensional model representation based uncertainty propagation algorithm coupled with layer-wise stochastic finite element model of composites is developed to achieve computational efficiency. The finite element formulation is based on Mindlin's theory considering transverse shear deformation. Numerical results are presented for the stochastic natural frequencies of delaminated composites along with a comprehensive deterministic analysis. Further, an inevitable effect of noise is induced in the surrogate based analysis to explore the effect of various errors and epistemic uncertainties involved with the system.
       
  • Finite element modelling of flexural behaviour of geosynthetic
           cementitious composite mat (GCCM)
    • Abstract: Publication date: Available online 26 July 2018Source: Composites Part B: EngineeringAuthor(s): Tidarut Jirawattanasomkul, Nuttapong Kongwang, Pitcha Jongvivatsakul, Suched Likitlersunag This paper presents a finite element modelling of a new geosynthetic cementitious composite material called GCCM. The framework adopted a concept of concrete externally bonded by fibre-reinforced polymer (FRP). The existing bond-slip model was used to predict a flexural behaviour of GCCM, considering the effect of needle-punch process during manufacturing. The finite element modelling was calibrated against the experimental data of bending tests. The parameter optimisation was employed to define a set of the bond-slip model parameters. The analytical load-displacement curves predicted by the bond-slip model could agree well with those obtained from the experiments.
       
  • Highly filled biochar/ultra-high molecular weight polyethylene/linear low
           density polyethylene composites for high-performance electromagnetic
           interference shielding
    • Abstract: Publication date: Available online 26 July 2018Source: Composites Part B: EngineeringAuthor(s): Suiyi Li, An Huang, Yann-Jiun Chen, Dagang Li, Lih-Sheng Turng Highly filled (up to 80 wt%) biochar/ultra-high molecular weight polyethylene (UHMWPE)/linear low density polyethylene (LLDPE) composites with excellent electromagnetic interference (EMI) shielding performance were successfully prepared using mass-producing extrusion and hot-compression methods. Carbonizing bamboo charcoal (BC1100) at 1100 °C resulted in a graphite-like structure leading to good electrical conductivity and a high specific surface area. The surface morphology and crystalline structure, as well as the thermal, mechanical, electrical, and EMI shielding properties of the composites, were characterized. The addition of BC1100 enhanced the Young's modulus, tensile strength, and hardness of the composites, but reduced the ductility. Most importantly, the BC1100 biochar remarkably improved the electrical conductivity and EMI shielding effectiveness (SE) of the composites. In particular, the composite with 80 wt% BC1100 exhibited a conductivity of 107.6 S/m, one of the highest values among reported conductive polymer composites fabricated by melt processing, and a very high EMI SE of 48.7 dB (99.998% attenuation) at 1500 MHz. The specific EMI SE of the 80 wt% BC1100 composite was 39.0 dB cm3/g, nearly four times higher than that of copper (10 dB cm3/g). These results suggest a new, scalable way of effectively utilizing renewable biochar in conductive polymer composites, especially for EMI shielding applications.Graphical abstractImage 1
       
  • In-situ heat dissipation monitoring in adhesively bonded composite joints
           under dynamic compression loading using SHPB
    • Abstract: Publication date: Available online 25 July 2018Source: Composites Part B: EngineeringAuthor(s): Sonia Sassi, Mostapha Tarfaoui, Hamza Ben Yahia It is well known that the mechanical energy transforms partly into heat under impact and this heat can affect the material integrity. In this research, heat generation in adhesively bonded composite joints during dynamic compression tests had been studied because of their frequent use in naval applications. Experiments were designed to identify the mechanisms that lead to the heat generation and to measure the temperature rise in the specimens under various loading conditions. Compression Split Hopkinson Pressure Bars (SHPB) coupled with a high-speed and infrared cameras were used for real-time monitoring of change in dynamic parameters, damage kinetics and heat generation in the samples with respect to variation in strain rates. In addition, small thermocouples were also attached with the specimens and insterted at the heart of the material for assessing the change in temperature. During the experiments, significant temperature rise was observed, primarily at high strain rates. Mechanical, thermal and high speed photographs results altogether indicate that the rise of temperature was mainly due to damage in material. Significant variation in the heat generation by changing strain rate was observed. This variation was explained as different damage modes were activated at each strain rate. These results have shown that thermomechanical coupling must be taken into account when developing damage models under impact.
       
  • Elastoplastic nonlinear FEM analysis of FGM shells of Cosserat type
    • Abstract: Publication date: Available online 25 July 2018Source: Composites Part B: EngineeringAuthor(s): Stanisław Burzyński, Jacek Chróścielewski, Karol Daszkiewicz, Wojciech Witkowski The paper is a continuation of [1] where the formulation of the elastic constitutive law for functionally graded materials (FGM) on the grounds of nonlinear 6-parameter shell theory with the 6th parameter (the drilling degree of freedom) was presented. Here the formulation is extended to the elasto-plastic range. The material law is based on J2 Cosserat plasticity and employs the well-known Tamura-Tomota-Ozawa (TTO) [2] mixture model with additional formulae for Cosserat material parameters. Formulation is verified by solving a set of demanding analyses of plates, curved and multi-branched shells, including geometry, thickness and material distribution variation parameter analyses.
       
  • Novel TiB2-reinforced 316L stainless steel nanocomposites with excellent
           room- and high-temperature yield strength developed by selective laser
           melting
    • Abstract: Publication date: Available online 25 July 2018Source: Composites Part B: EngineeringAuthor(s): Bandar AlMangour, Young-Kyun Kim, Dariusz Grzesiak, Kee-Ahn Lee Selective laser melting (SLM) is an emerging additive manufacturing process to fabricate multifunctional parts by locally melting and consolidating powders in a layer-by-layer manner. Its flexibility enables the development of new alloys and metal matrix composites with unique, fine microstructures and complex-shaped components that are all difficult to realize with traditional manufacturing processes. This study investigates how TiB2 nanoparticle reinforcements affect the microstructure and high-temperature deformation behavior of a 316 L stainless steel matrix. In SLM-processed pure stainless steel, fully directional columnar grains were observed, whereas TiB2 nanoparticles added to the steel matrix significantly reduced sizes of the molten pools and grains and disrupted the directional structures. A chemical analysis revealed no compositional difference between the boundary and interior of the molten pool areas of the SLM-processed TiB2/316 L nanocomposites, suggesting that elements did not segregate macroscopically. However, for higher TiB2 contents, alloying elements microsegregated at the boundaries of cellular structures due to the particle accumulation structure mechanism. Transmission electron microscopy confirmed the existence of mostly cube-like TiB2 nanoparticles both at the boundaries and in the interiors of the cellular structures. The nanocomposites exhibited high compressive yield strength and ductility at room and high temperatures, except at 600 °C, where embrittlement was observed. Observing the microstructure and flow stress of nanocomposites deformed at 700 and 800 °C shed light on the dynamic recovery and dynamic recrystallization phenomena. However, several conventional strengthening effects could not predict the entire yield strength increase. Thus, a novel microsegregation strengthening mechanism was presented to explain the effect of TiB2 on the refined microstructure, and the novel microsegregation phenomenon and the enhanced mechanical properties were correlated. Hence, the SLM process shows high potential for fabricating new materials with outstanding properties.Graphical abstractImage 1
       
  • Mixed Mode delamination in carbon nanotube/nanofiber interlayered
           composites
    • Abstract: Publication date: Available online 25 July 2018Source: Composites Part B: EngineeringAuthor(s): Ozge Kaynan, Yagmur Atescan, Elif Ozden-Yenigun, Hulya Cebeci Laminated composites mostly suffer from layer separation and/or delamination, which may affect the stiffness, strength and lifetime of structures. In this study, we aim to produce micron-scale thin carbon nanotubes (CNTs) reinforced adhesive nanofibrous interleaves and to explore their effectiveness when incorporated into structural composites. Neat polyvinyl butyral (PVB) and solutions containing low fractions of CNTs from 0.5 to 2 wt.% were electrospun directly onto carbon fiber prepregs. These interlayered laminates were cured above the glass transition temperature (Tg) of PVB to achieve strong interlaminar binding and also to resist crack re-initiation. The effect of CNTs presence and their mass fractions both on total Mixed-Mode I + II fracture toughness (GC) and crack length was investigated under Mixed-Mode I + II loading. Almost 2-fold increase in GC was reported in interlayered composites compared to non-interlayered laminates, associated to toughening effect of adhesive PVB/CNTs nanofibrous interlayers. Furthermore, the post-fracture analysis revealed the aid of CNTs interleaves in retarding delamination and afterward stabilization of crack propagation.Graphical abstractImage 1
       
  • Laser ablation behavior of nano-copper particle-filled phenolic matrix
           nanocomposite coatings
    • Abstract: Publication date: Available online 24 July 2018Source: Composites Part B: EngineeringAuthor(s): Chen Ma, Zhuang Ma, Lihong Gao, Yanbo Liu, Jiawei Wang, Mingying Song, Fuchi Wang, Hatsuo Ishida Laser is becoming increasing threat to materials due to its high energy that can induce thermal damage, especially high energy continuous-wave (CW) laser. In this case, laser protection has attracted more and more concerns. Nanocomposite coatings that consist of nano-copper filler with phenolic resin matrix have been designed and successfully prepared to meet the requirement of anti-laser ablation. The anti-laser ablation ability of the nanocomposite coatings is evaluated through the temperature of the back-surface substrate. Results show that the transpiration cooling effect of nano-copper particles do improve the anti-laser ablation property of the coating. The residual char with porous structure which is the pyrolysis result of phenolic resin plays a key role as a barrier to prevent laser from irradiating inside of the coating. The amorphous carbon gradually transforms to graphitic structure during CW laser irradiation. The latter has better stability at high temperature, improving anti-laser ablation. The micro-morphologies and element content analysis indicate that the evaporation of nano-copper particles occurs layer by layer until the total pyrolysis of phenolic resin located in the vertical direction of the coating. All the analyses show that this nanocomposite coating has excellent performance as a protective shield to anti-laser damage.
       
  • Fabrication and characterization of synergistic Al-SiC-GNPs hybrid
           composites
    • Abstract: Publication date: Available online 20 July 2018Source: Composites Part B: EngineeringAuthor(s): Mahmut Can Şenel, Mevlüt Gürbüz, Erdem Koç The traditional aluminum matrix composites were fabricated using pure graphene nanoplatelets (GNPs) and silicon carbide (SiC) in aluminum matrix due to the solid lubricant properties of GNPs and high hardness, compressive strength of SiC. However, a few studies are available on the effect of the binary SiC-GNPs reinforced aluminum hybrid composites in large scale. In this study, aluminum matrix was reinforced with pure SiC (varying from 0 to 30 wt.%), GNPs (changing from 0.1 to 0.5 wt.%) and their hybrid form (SiC-GNPs) by powder metallurgy method. From the results, hardness was improved to 79 ± 2 HV (Al-30SiC) and 57 ± 2.5 HV (Al-0.1GNPs) from 28 ± 2 HV, respectively. Similarly, compressive strength of the pure SiC and GNPs reinforced aluminum composite was enhanced to 221 ± 6 (Al-30SiC) and 138 ± 4 MPa (Al-0.5GNPs) from 106 ± 4 MPa, respectively. Interestingly, the highest hardness and compression strength of the hybrid composites were measured as 85 ± 2.6 HV (Al-30SiC-0.5GNPs) and 271 ± 7 MPa (Al-30SiC-0.1GNPs), respectively.
       
  • Free vibrations of FG elastic Timoshenko nano-beams by strain gradient and
           stress-driven nonlocal models
    • Abstract: Publication date: Available online 20 July 2018Source: Composites Part B: EngineeringAuthor(s): R. Barretta, S. Ali Faghidian, R. Luciano, C.M. Medaglia, R. Penna Size-dependent vibrational behavior of functionally graded (FG) Timoshenko nano-beams is investigated by strain gradient and stress-driven nonlocal integral theories of elasticity. Hellinger-Reissner's variational principle is preliminarily exploited to establish the equations governing the elastodynamic problem of FG strain gradient Timoshenko nano-beams. Differential and boundary conditions of dynamical equilibrium of FG Timoshenko nano-beams, with nonlocal behavior described by the stress-driven integral theory, are formulated. Free vibrational responses of simple structures of technical interest, associated with nonlocal stress-driven and strain gradient strategies, are analytically evaluated and compared in detail. The stress-driven nonlocal model for FG Timoshenko nano-beams provides an effective tool for dynamical analyses of stubby composite parts of Nano-Electro-Mechanical Systems.
       
  • Fire performance of polymer-based composites for maritime infrastructure
    • Abstract: Publication date: Available online 4 July 2018Source: Composites Part B: EngineeringAuthor(s): Phuong Tran, Quynh Thuy Nguyen, K.T. Lau The fire performance of fiber-reinforced polymer composites used in naval ships, submarine and maritime structures are reviewed and discussed in this work. Polymer composites has been developed and used for wide range of applications in aircraft, spacecraft, boats, ships, automobiles, civil infrastructure, sporting goods and consumer products grown at an impressive rate over the last 50 years. In particular, the use of composites for naval vessels continues to grow in coming years for various applications including decks, bulkheads, propellers, propulsion shafts, pipes, pumps, and other machinery parts. Composites demonstrated as ideal materials in a wide variety of applications due to many outstanding physical, thermal-mechanical and chemical properties. Specifically, composites offers high specific stiffness and specific strength, low density, good fatigue resistance, outstanding corrosion resistance, excellent thermal insulation and low thermal expansion over many metal alloys. A major disadvantage of many composite materials is poor performance when exposed to high temperatures, in which the organic matrix decomposes with the potential to release of heat, smoke, soot and toxic volatiles. Offshore environment poses even more challenges for naval structure design, where fires although infrequent can have catastrophic effects due to their intensity and the isolation of the offshore construction. Although most of polymer composites are flammable, their resistance to pyrolysis can be improved.
       
 
 
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