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  • Facile synthesis of Ag/ZrO2 nanocomposite as a recyclable catalyst for the treatment of environmental pollutants
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-21
    Mehdi Maham; Mahmoud Nasrollahzadeh; S. Mohammad Sajadi
    更新日期:2020-01-21
  • Effects of fiber geometry and orientation distribution on the anisotropy of mechanical properties, creep behavior, and thermal expansion of natural fiber/HDPE composites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-21
    Xiaolong Hao; Haiyang Zhou; Binshan Mu; Lei Chen; Qiong Guo; Xin Yi; Lichao Sun; Qingwen Wang; Rongxian Ou
    更新日期:2020-01-21
  • Exchange coupling and improved properties of the multilayer CoFe2O4/La0.7Sr0.3MnO3 thin films
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-21
    Xianwu Tang; Shunjin Zhu; Renhuai Wei; Ling Hu; Jie Yang; Wenhai Song; Jianming Dai; Xuebin Zhu; Yuping Sun

    Hard/soft interface plays a role in the properties of the composite metal-based magnets, while it is less talked in the composite permanent oxide magnets on the magnetic interaction and properties due to easy interdiffusion. Here, multilayer thin films composed with hard CoFe2O4 phase and soft La0.7Sr0.3MnO3 layers were choose and synthesized without interdiffusion by a chemical solution method. Furthermore, the effects of the annealing temperature and the number of soft layer on the magnetic interaction and properties are investigated. All composite films behavior as one rigidly coupled composite magnet at room temperature, and the magnetic properties increase with increasing annealing temperature. The coercivity and maximum magnetic energy product can respectively reach 8.27 kOe and 2.4 MG Oe at the temperature of 300 K. Exchange coupling was effectively enhanced and even dominate the magnetic interaction with less soft layers for the in-plane direction. Conversely, dipolar interaction predominates, but becomes weak in the composite films with more soft layers and attenuates with increasing annealing temperature for the out-of-plane direction. All of the results suggest that a suitable grain size of the hard phase and an improved interface may be more important for a rigidly coupled composite oxide magnet with good performance.

    更新日期:2020-01-21
  • Hierarchically porous surface of PEEK/nMCS composite created by femtosecond laser and incorporation of resveratrol exhibiting antibacterial performances and osteogenic activity in vitro
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-20
    Guiquan Cai; Hui Wang; Yun Kyung Jung; Zhiyan Xu; Jiahong Zhang; Jiye He; Dongliang Wang; Jung-Woog Shin; Rames Kaewmanee; Saha Nabanita; Jie Wei

    To further improve the surface properties of polyetheretherketone (PEEK)/nanoporous magnesium calcium silicate (nMCS) composite (PMC), hierarchically porous surface of PMC (PMCF) were created by femtosecond laser, and resveratrol (RV) was incorporated into the porous surface of PMCF ([email protected]). Compared to PMC with flat surface, PMCF contained not only two types of micropores with different sizes (around 20 μm and 0.5 μm) but also nanopores (around 4 nm), which exhibited remarkably increase in surface roughness and protein adsorption. In addition, PMCF displayed a slow-release of RV while PMC showed a burst-release of RV into cell cultured medium. Moreover, compared with PMC and PMCF, [email protected] with antibacterial performances inhibited the growth of E. coli and S. aureus thanks to the release of RV. In addition, compared with PMC, PMCF and [email protected] significantly promoted adhesion and proliferation of rat bone mesenchymal stem cells (BMSC). Furthermore, compared with PMCF, [email protected] obviously enhanced the proliferation and osteogenic differentiation as well as bone related genes expressions of BMSC. The results demonstrated that PMCF with hierarchically porous surface and incorporating of RV displayed antibacterial performances and osteogenic activity in vitro, Therefore, as a drug-loaded implant, [email protected] with good cytocompatibility would have a big potential for applications in orthopaedic fields.

    更新日期:2020-01-21
  • Cracking behavior of geopolymer concrete beams reinforced with steel and fiber reinforced polymer bars under flexural load
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-20
    Khuram Rashid; Xiaoda Li; Yan Xie; Jun Deng; Faji Zhang

    The cracking pattern and spacing in reinforced concrete (RC) structures considerably influence structural performance. Cracking may be severe with the utilization of fiber reinforced polymer (FRP) bars as compared to steel due to its low modulus of elasticity. In this study, the crack initiation, propagation and spacing, failure mode and ultimate load of RC beams reinforced with steel, basalt FRP (BFRP) and carbon FRP (CFRP) were investigated. A four-point bending test was conducted on fifteen RC beams. The beams with FRP bars exhibited worse cracking resistance and faster propagation throughout the loading process than those including steel bars. The cracking pattern was associated with failure modes from flexural to flexural-shear failure, which ultimately influenced the failure load. Furthermore, the crack spacing was analytically evaluated by three models used in conventional RC structures. The results showed that incorporating the rebar-concrete bond strength in Zhang's model resulted in more precise analytical values. Then, the bond strengths of all the FRP-concrete beams were evaluated by four codes. A strong correlation between the analytical and experimental crack spacing values was observed when considering code Canadian Standard Association (CSA) S806-12, and a significant margin of safety was obtained when considering the Japanese Society of Civil Engineering (JSCE) code.

    更新日期:2020-01-21
  • Silica nanoparticles surface charge modulation of the electroactive phase content and physical-chemical properties of poly(vinylidene fluoride) nanocomposites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-20
    Sylvie Ribeiro; Rafaela Meira; Daniela M. Correia; Carmen R. Tubio; Clarisse Ribeiro; Carlos Baleizão; Senentxu Lanceros-Méndez
    更新日期:2020-01-21
  • Rapid synthesis of solid amine composites based on short mesochannel SBA-15 for CO2 capture
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-20
    Beibei Ma; Rijia Lin; Hui He; Qinghua Wu; Shuixia Chen
    更新日期:2020-01-21
  • Bioinspired functionally graded gyroid sandwich panel subjected to impulsive loadings
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-20
    Chenxi Peng; Phuong Tran

    Gradual and localised changes in mechanical properties can be achieved by functionally graded cellular structures with the aim to improve structural performance. Gyroid belongs to a class of cellular structures that naturally inspired continuous non-self-intersecting surfaces with controllable mechanical properties. In this work, dynamic compression on functionally graded gyroid and sandwich composite panels constructed from functionally graded gyroid core and metallic facets are numerically investigated and compared to evaluate the dynamic behaviours when subjected to extreme loadings. The Finite Element Analysis (FEA) is employed to characterises the deformation of proposed structures considering the rate-dependent properties, elastoplastic response and nonlinear contact. The Johnson-Cook model is utilised to capture the rate-dependent dynamic responses of the gyroid panels. The numerical model is then validated with experimental results under quasi-static compression. Owing to the symmetry, only a quarter of the gyroid panel is modelled using shell elements, which significantly reduces the computational cost. A series of studies are conducted to demonstrate the influences of different functionally graded cores on the blast resistances of gyroid composite panels. Reaction forces and critical stresses extracted from underneath protected structure are assessed. Gyroid sandwich structures clearly demonstrate unique dynamic crushing responses, impact energy mitigation & dissipation mechanisms, which leads to enhancement of the blast resistance.

    更新日期:2020-01-21
  • Light-weight, high-gain three-dimensional textile structural composites antenna
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-20
    Fujun Xu; Kun Zhang; Yipping Qiu

    Due to the multiple dimensional and embeddable characterizations, the three-dimensional woven structure is of great potential as a platform for multifunctional composites. As an example of this concept, we proposed a light-weight and high-gain three-dimensional woven spacer microstrip antenna (3DWS-MA) for the first time by integrating microstrip antenna into 3D woven spacer composites. The single-element 3DWS-MA showed superb electromagnetic performance with the gain value of 7.1 dB, which is more than four orders of magnitude higher than traditional microstrip antenna (2.5 dB). Furthermore, the 3DWS-MA maintained proper resonant frequency and impedance matching after the impact of 18 J, exhibiting excellent structural integrity.

    更新日期:2020-01-21
  • 更新日期:2020-01-21
  • Adjusting function of MoS2 on the high-speed emergency braking properties of copper-based brake pad and the analysis of relevant tribo-film of eddy structure
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-20
    Peng Zhang; Lin Zhang; Dongbin Wei; Peifang Wu; Jingwu Cao; Cairang Shijia; Xuanhui Qu

    In this paper, by studying the high-speed emergency braking performance of copper-base brake pads with different MoS2 contents and the corresponding structure of tribo-film, the adjusting function of MoS2 was revealed, which is mainly achieved by the reaction of MoS2 with Cu and Fe. The hard reaction products enhance the strength of the matrix and thus increase the resistance of plastic deformation. However, excessive addition of MoS2 in the matrix leads to the reduced particle size of Fe and the increased matrix discontinuities. Those reduce the deformation resistance of friction surface and the ability to hinder the movement of substances on friction surface, thereby resulting in formation of eddy structure on friction surface of the samples containing high content of MoS2 during high-energy braking. For the sample containing the optimum content of 2 wt % MoS2, the friction coefficient is relatively high and the wear loss is only 17.13% and 5.05% of the samples without MoS2 and with 10 wt % MoS2, respectively. The abnormal high wear loss and the reduction of friction coefficient is mainly determined by the dynamic process of formation and delamination of the eddy structure.

    更新日期:2020-01-21
  • Strain amplitude controlled fatigue of Flax-epoxy laminates
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-17
    Zia Mahboob; Habiba Bougherara

    Fatigue longevity and evolving material properties of Flax-epoxy laminates is examined under constant strain amplitude cycling. Several recent fatigue studies on Flax-composites, all of which were conducted under stress-control, found that certain laminates demonstrate a modulus increase over fatigue life, even while accumulating internal damage and permanent deformation. This study investigates whether such fatigue-stiffening phenomena are also observed under strain-control. Specimens of four layups ([0]16, [0/90]4S, [±45]4S, and [0/45/90/−45]2S) are tested under 5 Hz and strain ratio Rϵ=ϵminϵmax=0.1. Strain-life (ϵ–N) plots are generated, which are found to follow a consistent trend that can be modelled by a linearised relationship with identifiable parameters. No evidence of stiffening is observed. All specimens demonstrate stiffness degradation, thereby contradicting previous studies. The extent of degradation is proportional to loading applied. A directly proportional relationship is observed between strain-rate and measured modulus. It is proposed that the reported modulus increase in existing literature does not reflect any physical improvement of material stiffness, but is a consequence of stress-amplitude controlled loading conditions. As such, strain-controlled cycling may be more appropriate for fatigue studies on natural fibre composites.

    更新日期:2020-01-17
  • 更新日期:2020-01-16
  • Damage tolerance of CFRP airframe bolted joints in bearing, following bolt pull-through failure
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-15
    Ioannis K. Giannopoulos; Kaelan Grafton; Shijun Guo; Howard Smith

    The experimental study presented herein, investigated the residual strength of bolted joints on Carbon Fiber Reinforced Polymer (CFRP) airframe structures within the context of structural damage tolerance and airworthiness regulations. The damage scenario assumed, subjected a series of bolted joint CFRP laminate specimens to quasi-static bearing loading following bolt pull-through failure events of different magnitude. Representative CFRP laminate specimens manufactured from AS7/8552 carbon fiber/epoxy matrix system were artificially damaged under bolt pull-through loading, following the herein proposed modifications to the current pull-through ASTM testing procedure. The specimens were subsequently tested in static bearing loading for examining the specimen residual bearing strength. The residual joint bearing strength was related to the displacement travelled passed the initial failure stage in pull-through mode and was measured up to a maximum of a 13% decrease for the tested samples and the maximum damage imposed. The study explored of safe utilization of bolted joints at higher operating loading levels within the context of the current airworthiness regulations. The inherent damage arrest features of the joints were highlighted. The study concluded with comments and suggestions on the expansion of the current utilization spectrum of damaged bolted joints from pull-through loading in airframe design, bound by the current airworthiness certification requirements.

    更新日期:2020-01-15
  • The influence of fiber volume fraction and fiber length on the evolution of pore content and the paintability of sheet molding compounds
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-14
    Marton Kardos; Enrico Körner; Dayakar Penumadu; Niels Modler

    The porosity defects from components molded using sheet molding compounds is a well-recognized issue. It is the major source of paint defects in exterior applications, hindering the widespread use of these materials despite their inherent advantages over metals and thermoplastics. This study discusses the influence of fiber volume fraction and fiber length on the pore content and on the painted surface quality of class-A compounds. Compounds with varying glass fiber fraction and fiber length were compounded, compression molded and painted to analyze the influence of the aforementioned factors on the permeability of the fibrous network, the evolution of initial to final pore content and on the painted surface quality with regards to waviness and substrate-relevant paint defects. A new indicator, the pore transport efficiency factor is introduced to help quantify the related characterization feature. The results indicate that lower fiber fractions lead to decreased pore contents and thus, improved paintability.

    更新日期:2020-01-15
  • Evaluation of grit-blasting as a pre-treatment for carbon-fibre thermoplastic composite to aluminium bonded joints tested at static and dynamic loading rates
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-13
    Karthik Ramaswamy; Ronan M. O'Higgins; Ajay Kumar Kadiyala; Michael A. McCarthy; Conor T. McCarthy

    Light-weighting of transportation structures necessitates multi-material design employing composites and aluminium, with thermoplastic composites being of increasing interest to the industry. Adhesive bonding is a viable solution for joining dissimilar materials, but joint performance can be considerably affected by surface preparation. In this paper, alumina grit-blasting is investigated as a surface preparation technique for thermoplastic-matrix composites to be bonded to aluminium alloys. Grit-blasting is performed on composite adherends for varying durations, and the resulting chemical and morphological modifications are analysed using goniometry, profilometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Adhesively-bonded single-lap joints are tested at quasi-static and dynamic (0.5 m/s) loading rates, and fractography analysis is performed at macro and micro scales. It is found that high lap shear strength and work-to-failure can be achieved through optimisation of the grit-blasting parameters. The optimised process produces a composite surface with plasticised matrix, minimal fibre exposure, and favourable surface chemistry for adhesive bonding. Grit-blasting can thus be a simple, yet effective surface preparation technique for composites to be bonded to aluminium.

    更新日期:2020-01-13
  • Incorporation of functionalized reduced graphene oxide/magnesium nanohybrid to enhance the osteoinductivity capability of 3D printed calcium phosphate-based scaffolds
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-11
    Hossein Golzar; Dorsa Mohammadrezaei; Amir Yadegari; Morteza Rasoulianboroujeni; Mohadeseh Hashemi; Meisam Omidi; Fatemeh Yazdian; Mohammad Shalbaf; Lobat Tayebi

    Improving bone regeneration is one of the most pressing problems facing bone tissue engineering (BTE) which can be tackled by incorporating different biomaterials into the fabrication of the scaffolds. The present study aims to apply the 3D-printing and freeze-drying methods to design an ideal scaffold for improving the osteogenic capacity of Dental pulp stem cells (DPSCs). To achieve this purpose, hybrid constructs consisted of 3D-printed Beta-tricalcium phosphate (β-TCP)-based scaffolds filled with freeze-dried gelatin/reduced graphene oxide-Magnesium-Arginine (GRMA) matrix were fabricated through a novel green method. The effect of different concentrations of Reduced graphene oxide-Magnesium-Arginine (RMA) (0, 0.25% and 0.75%wt) on the morphology, mechanical properties, and biological activity of the 3D scaffolds were completely evaluated. Our findings show that the incorporation of RMA hybrid into the scaffold can remarkably enhance its mechanical features and improve cell proliferation and differentiation simultaneously. Of all scaffolds, β-TCP/0.25GRMA showed not only the highest ALP activity and cell proliferation after 14 days but it up-regulated bone-related genes and proteins (COL-I, RUNX2, OCN). Hence, the fabricated 3D printed β-TCP/0.25GRMA porous scaffolds can be considered as a high-potential candidate for BTE.

    更新日期:2020-01-13
  • Electrical and thermal conductivity of polyvinylidene fluoride (PVDF) – Conducting Carbon Black (CCB) composites: Validation of various theoretical models
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-10
    Ranvijai Ram; Vandna Soni; Dipak Khastgir

    Different composition dependent PVDF/CCB composites were prepared by solution mixing followed by casting technique. The morphology, crystallinity, electrical and thermal conductivity, sound velocity and storage modulus vary with composition. The effect of frequency, temperature and composition on electrical conductivity were investigated and electrical conductivity of these composites strongly depends on percolation threshold. The variation of thermal conductivity and storage modulus against temperature and concentration has also been investigated. The surface morphology has been viewed through Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Spectroscopy (AFM). The particle agglomerate structure of CCB was checked byHigh Resonance Transmission Electron Microscopy (HRTEM). Applicability of different theoretical models to predict electrical conductivity and thermal conductivity were also tested for these composites. To predict composition dependent thermal conductivity theoretical models like Series, Parallel, Geometrical mean, Maxwell, Nielsen Lewis, Hamilton-Crosser, and the Agari model have been used to check their validity for the present system.

    更新日期:2020-01-11
  • A study on adhesive characteristics of double cantilever beam specimens with inhomogeneous materials due to tensile and out-of-plane shear fractures
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-10
    J.W. Kim; J.U. Cho; C.D. Cho

    In this study, the adhesive characteristics of double cantilever beam specimens with the inhomogeneous adhesion materials due to tensile and out-of-plane shear fractures have been investigated. The experiments were conducted by applying a forced displacement rate of 3 mm/min at the upper position and fixing the lower position, while each experimental condition was maintained to be identical. In the tensile fracture of mode Ⅰ, the maximum reaction force was observed to be highest in the order of CFRP-Al, Al–Al_Foam, and CFRP-Al_Foam. The maximum energy release rate was highest in the order of Al–Al_Foam, CFRP-Al, and CFRP-Al_Foam. When the overall crack resistance curves were examined, all of the highest energy release rates could be seen to be produced at an early stage of cracking. In mode Ⅲ, the maximum reaction force was highest in the order of CFRP-Al, Al–Al_Foam, and CFRP-Al_Foam. The maximum energy release rate was observed to be highest in the order of CFRP-Al, CFRP-Al_Foam, and Al–Al_Foam. Considering that the higher reaction forces and energy release rates were produced in the specimen containing, it could be inferred that the use of a material with high rigidity increased the maximum strength of the adhesive.

    更新日期:2020-01-11
  • Shear behavior of woven and non-crimp fabric based thermoplastic composites at near-processing conditions
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-10
    Tobias Mattner; Michael Wrensch; Dietmar Drummer

    In intra-laminar shear testing of continuous fiber reinforced thermoplastic composites at near-processing conditions, several factors influence the measured forces in picture frame tests. These influences mostly result from tight clamping of the specimen in the frame and, depending on the heating strategy, possible unmelted areas near the clamping regions, yielding in a shift of the point of rotation of the fibers. An approach to compensate these effects has recently been suggested, but generally valid compensation settings could not yet be deducted. In addition, research on the shear properties of continuous fiber reinforced thermoplastics has been limited to quasi-static deformation speeds and thermodynamically stable temperature levels. This study examines the effect of high deformation speeds and temperature levels in the transitional region between melting point and recrystallization on the intra-laminar shear behavior of different types of continuous fiber reinforced thermoplastics to deduct a material behavior, which better resembles actual processing behavior by using a custom-built picture frame setup. The edge effects are analyzed to deduct generally recommendable compensation settings using a statistical approach. In addition, variations of the pathways of individual fibers in pre-forms are measured, revealing elongation reserves of 0.4–0.5%, which can be confirmed in picture frame tests. The results furthermore show the importance of performing material tests at near-processing conditions to deduct reliable material data for usage in forming simulation. Further research is necessary to understand the complex deformation behavior in the transitional region below melting point and before recrystallization is complete.

    更新日期:2020-01-11
  • Compression properties of polymeric syntactic foam composites under cyclic loading
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-10
    Z. Yousaf; M.J.A. Smith; P. Potluri; W.J. Parnell

    In the present work, polymer-based syntactic foams were studied under cyclic compression in order to investigate their compressibility, recoverability, energy dissipation and damage tolerance. These syntactic foams were manufactured by adding hollow polymer microspheres of various sizes and wall thicknesses into a polyurethane matrix. The associated loading and unloading curves during cyclic testing were recorded, revealing the viscoelastic nature of the materials. SEM images of the samples were obtained in order to study potential damage mechanisms during compression. It was observed that these syntactic foams exhibit high elastic recovery and energy dissipation over a wide range of compressional strains and the addition of polymer microspheres mitigates the damage under compressional loading.

    更新日期:2020-01-11
  • The evaluation of failure mode behavior of CFRP/Adhesive/SPCC hybrid thin laminates under axial and flexural loading for structural applications
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-10
    Muhammad Akhsin Muflikhun; Ryo Higuchi; Tomohiro Yokozeki; Takahira Aoki

    The failure mode behavior and the mechanical performance in terms of stress-strain of Carbon Fiber Reinforced Plastic - Steel Plate Cold Commercial (CFRP-SPCC) hybrid thin laminates are investigated in this study through axial tensile and flexural tests. Four different adhesives were used. Materials were characterized using Differential Scanning Calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). Surface behavior was monitored in real time and after completion (final failure) with an optical microscope during the tensile test. The results from DSC and FTIR show that the materials undergo complete curing. The results from the tensile test indicate that by adding SPCC in hybrid laminates, the premature failure of CFRP laminates can be delayed up to 58.5%. The result shows the strain at failure increases from 1.85% of CFRP laminates to 2.1% of hybrid laminates, which equals an increased rate of more than 13%. The flexural tests demonstrate that hybrid laminates have a higher strain value compared to CFRP laminates. With the addition of SPCC layers, the failure mode is shifted from premature fiber breakage to adhesive breakage followed by final failure with fiber breakage originating from the CFRP laminates.

    更新日期:2020-01-11
  • Development of a low cost and green microwave assisted approach towards the circular carbon fibre composites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-08
    Omid Zabihi; Mojtaba Ahmadi; Chao Liu; Roya Mahmoodi; Quanxiang Li; Minoo Naebe
    更新日期:2020-01-08
  • Flexible and robust silver coated non-woven fabric reinforced waterborne polyurethane films for ultra-efficient electromagnetic shielding
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-07
    Wei Ren; Huixin Zhu; Yaqi Yang; Yanhui Chen; Hongji Duan; Guizhe Zhao; Yaqing Liu
    更新日期:2020-01-07
  • Influence of anodization of aluminum 2024 T3 for application in aluminum/Cf/ epoxy laminate
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-07
    Alberto L. Santos; Roberto Z. Nakazato; Sebastian Schmeer; Edson C. Botelho

    This work deals with the processing and characterization of aluminum/carbon fiber/epoxy composites obtained from anodized and non-anodized aluminum plates. In this work, the electrochemical treatment employed was the phosphoric anodization, after chemical stripping. After this treatment, the fiber metal laminate (FML) coupons were laminated, the aluminum plates were interleaved with CF/epoxy prepreg layers. The next step was the use of hot compression molding technique in order to prepare the FML with and without anodized aluminum surface treatment, for comparison purposes. Several characterization techniques were used, such as: impact and perforation resistance analysis, laminar, translaminar (Iosipescu) and compression shear strength, in addition to optical macroscopy. After the analysis of the results, it was verified that the electrochemical treatment slightly reduces the impact and the perforation resistance of FML studied, because a more adhered interface promotes larger internal tensions and consequently reduces the capacity to absorb energy until failure. However, the adhesion properties were shown to be superior in the composites produced with the anodized plates. Additionally, the treatment proved to be an important means of obtaining FMLs, since most of the plates produced with non-anodized aluminum delaminated after a few weeks in stock, while the FML obtained from anodized aluminum did not delaminate after months of their production.

    更新日期:2020-01-07
  • A strain-displacement mixed formulation based on the modified couple stress theory for the flexural behaviour of laminated beams
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-07
    Luan C. Trinh; Rainer M.J. Groh; Giovanni Zucco; Paul M. Weaver

    A novel strain-displacement variational formulation for the flexural behaviour of laminated composite beams is presented, which accurately predicts three-dimensional stresses, yet is computationally more efficient than 3D finite element models. A global third-order and layer-wise zigzag profile is assumed for the axial deformation field to account for the effect of both stress-channelling and stress localisation. The axial and couple stresses are evaluated from the displacement field, while the transverse shear and transverse normal stresses are computed by the interlaminar-continuous equilibrium conditions within the framework of the modified couple stress theory. Then, axial and transverse force equilibrium conditions are imposed via two Lagrange multipliers, which correspond to the axial and transverse displacements. Using this mixed variational approach, both displacements and strains are treated as unknown quantities, resulting in more functional freedom to minimise the total strain energy. The differential quadrature method is used to solve the resulting governing and boundary equations for simply-supported, clamped and cantilever laminated beams. The deflections and stresses from this variational formulation for simply supported beams agree well with those from a Hellinger-Reissner stress-displacement mixed model found in the literature and the 3D elasticity solution given by Pagano. These strain-displacement models also accurately predict the localised stresses near clamped and free boundaries, which is confirmed by the high-fidelity Abaqus models.

    更新日期:2020-01-07
  • Effects of nanotube agglomeration on wave dynamics of carbon nanotube-reinforced piezocomposite cylindrical shells
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-07
    Hossein Bisheh; Timon Rabczuk; Nan Wu

    Dynamics of wave propagation in carbon nanotube (CNT)-reinforced piezocomposite cylindrical shells affected by nanotube agglomeration is investigated in this study for the first time by developing an analytical approach incorporating existing theories and models. The Mori-Tanaka micromechanics model in combination of the first-order shear deformation shell theory and wave propagation solution are employed to determine wave propagation characteristics of piezocomposite cylindrical shells reinforced with agglomerated CNTs. The effects of both partial and complete nanotube agglomeration on the effective elastic properties and wave dynamics are examined within various axial and circumferential wave numbers for different wave modes by solving an eigenvalue problem. It is found that nanotube agglomeration leads to the reduction of wave phase velocity as a result of decrease in the effective elastic properties. The developed methodology in this study can be used for analysis of the data of structural health monitoring by the non-destructive testing (NDT) in estimating the degree of nanotube agglomeration in nanocomposites.

    更新日期:2020-01-07
  • The fatigue repairing evaluation of hybrid woven composite patch with 2D&3D styles bonded Al-alloy plates under UV and thermal curing
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-03
    Jiaojiao Xi; Renkun Xia; Yannan He; Zhiqiang Yu

    The fatigue performance of repaired Al-alloy plates bonded by 2D&3D woven composite patch under UV and thermal curing was evaluated. The fatigue life N, crack growth rate da/dN, stress intensity factor range ΔΚ, the ‘m’ from Pairs equation and the fracture morphology were characterized to investigate the influence of patch styles and curing methods on the repairing effect. The results showed that fatigue performance was enhanced relative to unrepaired system. The stress was transferred from the crack tip to composite patch by adhesive for reducing the ΔK, and then da/dN was further restrained, contributing to the improvement of fatigue lifetime. The 3D patch had better repair effect than that of 2D patch, and UV curing was superior to thermal curing. It was more sensitive to the curing methods. The sample repaired by 3D patch under UV radiation (U-3D/25) presented the optimal performance, and fatigue lifetime reached 48651 cycles, increased by 806.14% relative to unrepaired system, which was proved by the decrease of ‘m’. The repair samples showed different fracture morphologies, which was attributed to changes of crack propagation path and stress distribution of different repair system. The fracture surface of U-3D/25 revealed ductile fracture features, presenting the optimal repair effect.

    更新日期:2020-01-04
  • Highly thermal conductive and electrical insulating polymer composites with boron nitride
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-03
    Meng Li; Mengjie Wang; Xiao Hou; Zhaolin Zhan; Hao Wang; Hui Fu; Cheng-Te Lin; Li Fu; Nan Jiang; Jinhong Yu
    更新日期:2020-01-04
  • Discontinuous micro-fibers as intrinsic reinforcement for ductile Engineered Cementitious Composites (ECC)
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-02
    Duo Zhang; Jing Yu; Haoliang Wu; Beata Jaworska; Brian R. Ellis; Victor C. Li

    Engineered Cementitious Composites (ECC) has demonstrated superior mechanical and durability performance than conventional concrete. In the micromechanical reinforcing system of ECC, fiber plays a pivotal role in establishing the ultrahigh tensile ductility and autogenous crack width control. This article reviews the state-of-the-art of discontinuous micro-fibers as intrinsic reinforcement of ECC regarding technical performance as well as environmental and economic impacts. Mechanical properties of ECC made with different micro-fibers, man-made or natural, and their embodied energy, emissions and material cost, are comprehensively surveyed. Further, studies on fiber hybridization are discussed regarding the combination of different fiber types to form synergetic reinforcements that mitigate total material cost, and potentially enhance the composite performance. Recommendations on fiber selections are highlighted and directions for future research are suggested.

    更新日期:2020-01-02
  • High-velocity impact onto a high-frictional fabric treated with adhesive spray coating and shear thickening fluid impregnation
    Compos. Part B Eng. (IF 6.864) Pub Date : 2020-01-02
    Yun Ho Kim; Sarath Kumar Sathish Kumar; Yurim Park; Hyunseok Kwon; Chun-Gon Kim

    The ballistic performance of a bullet-proof fabric can be increased by an increment in the friction between fibres. For enhancement of this performance, numerous studies on the shear thickening fluid (STF)-impregnated fabric have been conducted. The STF as a fluid, however, has inherent shortcomings. Our research aim is to understand and compare experimentally two different bullet-proof fabrics treated with a simple spray coating and STF impregnation. In this study, 71 single yarn pull-out and 90 high-velocity impact experiments were carried out. It was remarkable that the newly proposed Heracron fabric coated with a commercial coating spray increased by more than 90% the energy absorption before penetration, with only less than 15% of add-on weight. It was found that the polymeric anchors created on the fibre produce an exceptionally high level of friction between fibres, according to a microscopic morphological analysis and the single-yarn pull-out experiment. This study revealed the physical explanation of this coating method, showed its feasibility, and considered its effectiveness with excellent results.

    更新日期:2020-01-02
  • 更新日期:2020-01-02
  • Flexible La1.5Sr0.5NiO4/Poly(vinylidene fluoride) composites with an ultra high dielectric constant: A comparative study
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-30
    Keerati Meeporn; Prasit Thongbai

    Poly(vinylidene fluoride) (PVDF)–based polymer composites filled with high–permittivity La1.5Sr0.5NiO4 (LSNO) particles have been fabricated to produce a composite material with excellent dielectric performance and good mechanical flexibility. Micro–sized (μLSNO) and nano–sized LSNO (nLSNO) particles are used separately as fillers. The dielectric properties of the composites are determined by their particle sizes, resultant interfacial area, and the interparticle distances between the LSNO particles. The percolation threshold of the nLSNO/PVDF composite is lower than that of the μLSNO/PVDF composite. A greatly enhanced dielectric response with a high ε′ ≈ 565.9 at 1 kHz and room temperature and an effectively suppressed low loss tangent (tanδ ≈ 0.28) are obtained in the nLSNO/PVDF composite with a filler volume fraction of 30 vol %. The greatly enhanced ε′ value of nLSNO/PVDF can be explained by a combination of the interfacial polarization at the semiconducting nLSNO–insulating PVDF interfaces, an intrinsically giant ε′ response in nLSNO particles, and shorter interparticle distances between nLSNO particles in the PVDF matrix, while the retained low tanδ value is primarily attributed to the formation of a micro–capacitor microstructure.

    更新日期:2019-12-31
  • Halogen and halogen-free flame retarded biologically-based polyamide with markedly suppressed smoke and toxic gases releases
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-30
    Tongmin Cai; Junling Wang; Chuanhui Zhang; Min Cao; Sujun Jiang; Xin Wang; Bibo Wang; Weizhao Hu; Yuan Hu
    更新日期:2019-12-30
  • Aerogami: Composite origami structures as active aerodynamic control
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-26
    Mircea Cozmei; Tristan Hasseler; Everett Kinyon; Ryan Wallace; Antonio Alessandro Deleo; Marco Salviato

    This study explores the use of origami composite structures as active aerodynamic control surfaces. Towards this goal, two origami concepts were designed leveraging a combination of analytical and finite element modeling, and computational fluid dynamics simulations. Wind tunnel tests were performed at different dynamic pressures in conjunction with two different active control laws to test the capability of obtaining desired drag values. The experiments revealed excellent structural rigidity and folding characteristics under aerodynamic loading. These results are in very good agreement with one-way Fluid Structure Interaction (FSI) simulations, which show the potential of using high-fidelity modeling for the design and optimization of these structures. Future work will focus on developing advanced origami designs that allow for more deterministic folding as well as improved weight, stiffness, and fatigue characteristics in the use of materials.

    更新日期:2019-12-27
  • Dynamic interfacial debonding in sandwich panels
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-26
    Itay Odessa; Yeoshua Frostig; Oded Rabinovitch

    A nonlinear dynamic analytical approach is formulated aiming to investigate the dynamic interfacial debonding mechanism in sandwich panels. The approach is derived using the variational principle of virtual work and it incorporates the Extended High-Order Sandwich Panel Theory with a cohesive interface modeling for the interfaces between the face sheets and the core. The model adopts the first-order shear deformation theory kinematic assumptions for the face sheets along with a geometrically nonlinear behavior. The high-order small deformations kinematic assumptions that account for out-of-plane compressibility are considered for the core layer. The two interfaces link the three components of the panel together and the nonlinear traction-displacement laws introduce the interfacial nonlinearity into the model. The model considers dynamic effects in order to assess the influence of the inertial terms on the interfacial debonding mechanism and to examine the coupling between the two. The results of the dynamic analysis are compared with results of a static analysis for two cases: a sandwich panel with a pre-existing delamination subjected to an end-shortening loading and an intact sandwich panel subjected to three-point-bending. In the second case, the interfacial debonding triggers a dynamic response that substantially affects the structural behavior. The dynamic results, the assessment of the time scales of the process, and the comparison with the static results shed light on the significance of the dynamic nature of the interfacial debonding failure mechanism.

    更新日期:2019-12-27
  • Experimental and numerical study on creep and shrinkage effects of ultra high-performance concrete beam
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-24
    Li Zhu; Jia-Ji Wang; Xuan Li; Guan-Yuan Zhao; Xue-Jin Huo

    Compared with normal concrete, ultra high-performance concrete (UHPC) is of increasing interest for bridge engineering because of its superior tensile strength, compressive strength, and significantly enhanced durability. The creep and shrinkage effect have a significant influence on the long-term behavior of UHPC. However, the existing research on the time-dependent behavior of UHPC is still limited. In this research, based on numerical integration method, the ABAQUS user subroutine for simulating creep and shrinkage of both normal concrete (NC) and UHPC were developed by the recursive algorithm of adjacent stress increment in the time history. The accuracy of developed user subroutine was validated by creep and shrinkage test of reinforced NC beams. Subsequently, the long-term creep and shrinkage test of UHPC specimens was conducted with stress to strength ratio of 20%, 30%, and 40%, respectively. Based on the test results and the CEB-FIP Model code 1990, the simplified design formulas for predicting creep and shrinkage of UHPC were proposed respectively based on the developed UHPC material. In the proposed design formulas, the final shrinkage strain was 145 με, and the final creep coefficient was 0.46 for the developed UHPC specimens based on the test environment condition. The comparison between the test result and proposed formulas indicated good applicability and accuracy of the proposed formulas. Based on the developed ABAQUS user subroutine and the proposed design formula for creep and shrinkage, the finite element (FE) models of RC beam and UHPC beam were developed. The influence of creep and shrinkage on the long-term mechanical behavior of simply supported prestressed beams were investigated.

    更新日期:2019-12-25
  • Effect of temperature on the bond behaviour of GFRP bars in concrete
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-11-16
    Sandor Solyom; Matteo Di Benedetti; Maurizio Guadagnini; György L. Balázs

    Glass Fibre Reinforced Polymer (GFRP) bars have been employed as internal reinforcement for concrete members when corrosion of the commonly used steel bars is expected to be an issue. While a good bond is anticipated between GFRP bars and concrete at ambient temperature, the bond performance at high temperature is expected to be reduced due to the physical and mechanical changes that the matrix undergoes at temperatures approaching the glass transition temperature (Tg). Up to date this phenomenon has only been marginally investigated and most of the available bond tests are performed at ambient temperatures after cooling of the heated specimens. This paper presents the results of an experimental investigation on the bond behaviour of GFRP bars in concrete and exposed to temperature levels ranging from ~20 °C to 300 °C. The test specimens, consisting of an indented GFRP bar embedded in a cylindrical concrete block, were heated in an electric furnace. The pull-out tests were carried out within the furnace only after the temperature level, measured with thermocouples at the interface of GFRP and concrete, stabilized to the desired value. The paper discusses the effect of temperature on bond behaviour in terms of bond strength, bond stress-slip relationships and failure modes. A contactless technique measuring the free-end slip during pull-out tests at high temperatures was developed and its effectiveness demonstrated. Finally, the experimental results were used to calibrate the parameters of the two most widely used analytical models: mBPE and CMR.

    更新日期:2019-12-25
  • Direct tensile self-sensing and fracture energy of steel-fiber-reinforced concretes
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-23
    Duy-Liem Nguyen; My Ngoc-Tra Lam; Dong-Joo Kim; Jiandong Song

    Based on the experimental tests, the tensile self-sensing and fracture energy of steel-fiber-reinforced concretes (SFRCs) were focused to investigate. Firstly, the plain mortar matrix of SFRCs produced the strain-softening behavior and no self-sensing ability. Secondly, among six fiber types with same amount 1.5 vol.-% as follows: macro twisted (T30/0.3), macro smooth (S30/0.3), macro hooked (H30/0.375), meso twisted (T20/0.2), meso smooth (S19/0.2) and micro smooth (S13/0.2), the T20/0.2 revealed the highest first gauge factor (GFcc) and first-cracking strength whereas the S30/0.3 produced the highest first-cracking strain. Thirdly, the strain-sensing capacity of SFRCs using macro twisted fiber was observed to increase with increasing of fiber content in range of 0–2.0 vol.-%. Fourthly, in evaluating three SFRC matrices with same amount 1.5 vol.-% macro hooked fibers including M1 (control), M2 (added CB), M3 (added GGBS), M2 produced a significant enhancement in both self-sensing capacity and tensile strength while M3 produced a slight enhancement of them, in comparison with M1. Finally, the fracture energy of the investigated SFRCs were comparatively evaluated as follows: the ratio between elastic fracture energy and total fracture energy was the lowest, from 0.02 to 0.08 while the ratio between localized fracture energy and total fracture energy was the highest, from 0.38 to 0.82.

    更新日期:2019-12-23
  • Characterisation on the hygrothermal degradation in the mechanical property of structural adhesive: A novel meso-scale approach
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-11-17
    Xiao Han; Edmund Pickering; Arixin Bo; Yuantong Gu

    Structural adhesives are being increasingly used for bonding of dissimilar materials, however environmental degradation remains a significant challenge limiting the bonding reliability. A common form of degradation comes from water ingress, regarding which there is limited quantitative understanding of how water diffusion affects the adhesive local mechanical properties. This work proposes a meso-scale approach to characterise the influence of water diffusion on local mechanical properties of structural adhesives at elevated temperature, aiming to develop a model of degradation due to water exposure. Gravimetric study was conducted on adhesives immersed in deionised and 5 wt% NaCl water, to obtain water diffusion characteristics. The immersed specimens were periodically removed from the aqueous environment and precisely cut to expose the internal section. The samples were then indented using nanoindentation to extract the modulus and hardness distribution. SEM observation was conducted to analyse the microscopic morphology and ageing mechanism. Experimental results revealed that water diffusion caused significant local (meso-scale) degradation in adhesive mechanical properties. Increase in local moisture concentration led to greater degradation as moisture gradually diffused inward. Comparing to salt water immersion, the elastic modulus and hardness of adhesive saturated in deionised water decreased by further 5.9% and 11.9%, respectively. The developed degradation model coupled with insights from ageing mechanism provides a detailed understanding of degradation in adhesive property due to water diffusion. The proposed characterisation approach can be readily applied to other adhesives. Furthermore, this model allows for degradation of such adhesives to be reasonably predicted through FE modelling effort.

    更新日期:2019-12-23
  • Effect of matrix and fibre type on the impact resistance of woven composites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-21
    Jonas Claus; Rafael A.M. Santos; Larissa Gorbatikh; Yentl Swolfs

    Thermoplastic composites are emerging in the automotive industry as serious competitors to typical epoxy composites thanks to their higher toughness and reprocessability. Additionally, composites with polymer fibres can yield higher impact resistance than composites with conventional structural fibres like carbon and glass, while still delivering a high stiffness. In this work, woven composites with different fiber types (aramid, poly(p-phenylene-2,6-benzobisoxazole) (PBO), polyarylate (PAR), carbon) and different matrices (epoxy, polypropylene) were investigated under penetrating impact. It was found that aramid-PP composites absorb 2.82 times the energy of aramid-epoxy. PBO-PP absorbed almost twice as much energy as the other polymer fibre composites. PBO-PP and PAR-PP fractured the specimen with an unusual “X” shape while all other composites exhibited a “+“shape, which is typical for woven fabric composites. It is hypothesised that the unusual failure shape and the high energy absorption are linked to the high fibre anisotropy.

    更新日期:2019-12-21
  • Strength and toughness trade-off optimization of nacre-like ceramic composites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-20
    Kaoutar Radi; David Jauffres; Sylvain Deville; Christophe L. Martin

    Bio-inspired by abalone nacre, all ceramic brick-and-mortar composites with impressive mechanical properties have been recently manufactured. Albeit comprising only brittle constituents, extrinsic reinforcement mechanisms impart to these nacre-like ceramics high toughness and non-catastrophic crack propagation properties. While several models have been developed to understand the mechanical properties of natural and synthetic brick-and-mortar materials, they have always considered a ductile interface and focused mostly on intrinsic toughening mechanisms. Modeling so far has not captured the extrinsic toughening mechanisms responsible for the properties of nacre-like ceramics. Here we show that the Discrete Element Method (DEM) can account for reinforcement mechanisms such as microcracking and crack deflection, and quantitatively assess strength, initiation toughness and crack growth toughness. Two approaches are studied to enhance strength and toughness of nacre-like ceramics, either by reinforcing the interface globally (an increase of the interface strength) or locally (addition of nano-bridges). We combine the results to provide design guidelines for synthetic brick-and-mortar composites comprising only brittle constituents.

    更新日期:2019-12-21
  • Hybrid multi-cell thin-walled tubes for energy absorption applications: Blast shielding and crashworthiness
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-20
    Mahmoud Abada; Ahmed Ibrahim

    Nowadays, thin-walled structures are recognized for their significance in numerous technical fields particularly in automotive, aeronautics, and structural engineering. State-of-the-art studies reveal various techniques for improving energy absorptions of thin-walled structures, and each technique has its pros and cons. This paper proposes a combination of two energy absorption techniques to attain a high-level energy absorber component applicable to a wide range of blast-resistant design and crashworthiness applications. Thus, experimental and numerical investigations have been conducted to study the influence of applying internal stiffeners and staking composite layers on the behavior of aluminum (AL) thin-walled tubes. Single, double, and quadruple thin-walled metallic and hybrid tubes were tested under axial quasi-static compression test. The specimens were fabricated from unidirectional CFRP, epoxy resin and aluminum alloy T6061-T6. Various crashworthiness parameters were assessed such as the absorbed crash energy, specific energy absorption, crush force efficiency, average crushing load and peak load absorbed in order to highlight the behavior of the novel configurations. The hybrid quadrable multi-cell structure showed the highest energy absorption capabilities between the other proposed configurations. Its energy absorption improved by 116% compared to the solo hollow AL tube. In addition, nonlinear finite element analysis (FEA) using the commercial ANSYS-LSDYNA Workbench software was utilized to verify the experimental results. Numerical simulations showed very good decent agreement with the experimental results. The energy absorption of the proposed techniques has been significantly improved, with the most effective configuration (Hybrid quadruple-cell) showed 131.70% more than the control single-cell AL tube.

    更新日期:2019-12-20
  • The experimental and numerical study on the mechanical behaviours of adhesively bonded joints
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-20
    Elanur Çelebi̇ Kavdir; Murat Demir Aydin

    Experimental and numerical analyzes of single lap joints formed by combining AA2024-T3 aluminum alloys with two-component liquid structural adhesive DP410 were carried out in the present study. Tension and four-point bending experiments of single lap joints were performed in the experimental analysis section of this study in addition to 2-D Digital Image Correlation (DIC) analyses performed via the processing of the images obtained during these experiments. Whereas, three dimensional nonlinear finite element analyses of tensile and four point bending of single lap joints were performed for the numerical analysis section of the study by taking into consideration the load and boundary conditions applied during experimental analyses. Normal and shear strain distributions obtained via DIC and finite element method were compared by taking into consideration the middle line of the adhesive layer in the case of tensile and four-point bending loads of single lap joints. As a result of this comparison, it was found that there was a sufficient level of compatibility (not very close agreement) in strain distributions between finite element analyzes and DIC technique. As a result, it can be said that three-dimensional DIC analysis will yield more harmony and more accurate results when it is taken into account that three-dimensional finite element analysis and 2D DIC analysis were performed in the study.

    更新日期:2019-12-20
  • Effect of volume fraction and unidirectional orientation controlled graphite on thermal properties of graphite/copper composites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-20
    Jun-Ho Jang; Hyun-Kuk Park; Jeong-Han Lee; Jae-Won Lim; Ik-Hyun Oh

    This study aims to investigate the effect of the orientation of Gr powder and the volume fraction of Cu and Gr on the thermal conductivity (TC) and coefficient of thermal expansion (CTE) of Cu-Gr composites. Coarsening Gr flake (CGF) powder was coated with Cu through electroless plating (EP) method and was then sintered using pulsed current activated sintering. The present study confirmed that the presence of Cu oxide layer formed between Cu layer and CGF powder via electroless plating process and how it decomposes during the pulsed current activated sintering process. The anisotropy Gr has different characteristics depending on the bonding direction. In order to control the bonding direction of outstanding thermal properties of Gr, a stacking-pressing process was carried out, and the thermal conductivity was measured. The TC and CTE of Cu-Gr composites were measured in the longitudinal and transverse direction according to difference of Cu-Gr volume fraction, and were compared with theoretical value.

    更新日期:2019-12-20
  • Nonlocal bending and buckling of agglomerated CNT-Reinforced composite nanoplates
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-19
    Hamid Daghigh; Vahid Daghigh; Abbas Milani; Dwayne Tannant; Thomas E. Lacy; J.N. Reddy

    The study presents a nonlocal bending and buckling analysis of agglomerated carbon nanotube-reinforced composite nanoplates resting on a Pasternak foundation. A two-parameter micromechanics model incorporating agglomeration is used to obtain the effective mechanical properties of the nanoplates. Using Hamilton's principle, the governing differential equations are derived based on the Eringen's nonlocal elasticity theory and the sinusoidal shear deformation theory. The deflection and critical buckling load of the nanoplates are obtained by Navier's analytical solution. To verify the approach, the results are compared with experimental, analytical, and numerical findings in the literature. Detailed parametric studies are then performed to discuss the influences of the following parameters on the static bending and buckling response of the nanoplates with agglomerated CNTs: degree of agglomeration, nonlocal material scale parameter, temperature, foundation properties, volume fraction of CNTs, and length-to-thickness aspect ratio for the plate.

    更新日期:2019-12-19
  • Constitutive modeling for time- and temperature-dependent behavior of composites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-19
    Orzuri Rique; Xin Liu; Wenbin Yu; R. Byron Pipes

    Structural integrity, durability, and thermal stability represent critical areas for adequately modeling the behavior of composite materials. Polymeric matrices are prone to have time-dependent behavior very sensitive to changes in temperature that influence the effective properties of the composite. This study extends mechanics of structure genome (MSG) to construct a linear thermoviscoelastic model that allows to homogenize three-dimensional heterogeneous materials made of constituents with time- and temperature-dependent behavior. The formulation models the transient strain energy based on integral formulation for thermorheologically simple materials and treats thermal expansion creep as inherent material behavior. An analytical three-dimensional thermoviscoelastic homogenization solution has been derived for laminates modeled as an equivalent, homogeneous, anisotropic solid. Three-dimensional representative volume element (RVE) analyses and direct numerical simulations using a commercial finite element software have been conducted to verify the accuracy of the MSG homogenization. Unlike MSG, the RVE method exhibits limitations to properly capture the long-term behavior of effective coefficients of thermal expansion (CTEs) when time-dependent constituent CTEs are considered. The analyses of the homogenized properties also reveal that the shift factor of the polymeric matrix drives the temperature dependencies of the effective CTEs and engineering constants of the heterogeneous composite material regardless of the structural scale.

    更新日期:2019-12-19
  • Effect of tensile loading rate on interfacial properties of SMA/polymer composites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-19
    H. Fathi; M.M. Shokrieh; A. Saeedi

    In the present paper, the effect of loading rate on the interfacial properties of shape memory alloy (SMA) reinforced polymer composites is investigated using experiments and theoretical methods. First, experimental pull-out tests were performed at three different loading rates with the crosshead speeds of 0.3, 25 and 400 mm/min. The effect of loading rate on the tensile properties of SMA wires was also examined using tensile tests. For each loading rate, three pre-strain levels (0, 2 and 4%) were considered. A previously developed theoretical model was modified to determine the effect of loading rate on the interfacial behavior between SMA wires and polymer. According to results obtained, increasing the loading rate led to a reduction in the tensile strength and Young's modulus of SMA wires. On the other hand, interfacial shear strength between SMA and polymer was improved in higher loading rates. Enhancement of 70% was obtained for the interfacial shear strength at 400 mm/min in comparison with 0.3 mm/min crosshead speed. By comparing the results of the theoretical model and experiments good agreement was obtained. Moreover, the optical microscopy was utilized to investigate the effect of the generated recovery force in SMAs, on the compressive zone in SMA/polymer specimens.

    更新日期:2019-12-19
  • 更新日期:2019-12-19
  • 更新日期:2019-12-19
  • Characterization of rubberwood particleboard made using carboxymethyl starch mixed with polyvinyl alcohol as adhesive
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-18
    Junidah Lamaming; Ng Boon Heng; Amina Adedoja Owodunni; Sofie Zarina Lamaming; Nurul Khizrien Abd Khadir; Rokiah Hashim; Othman Sulaiman; Mohamad Haafiz Mohamad Kassim; Mohd Hazwan Hussin; Yazmin Bustami; Mohd Hazim Mohamad Amini; Salim Hiziroglu

    The aim of the study was to produce and characterize the modified starches and their suitability as wood adhesive for the particleboard manufacturing. The adhesive properties and particleboard manufactured from rubberwood using the modified starch and modified starch mixed with polyvinyl alcohol (PVA) were evaluated. Mixing of PVA with modified starch reduced the viscosity but increased the solid content and thermal property of the modified starch. Particleboard bonded with modified starch mixed with PVA also had improvement in physical and mechanical properties, showing great potential of modified starch and PVA as an adhesive for the green particleboard with good properties.

    更新日期:2019-12-18
  • Flexural deformation behavior of carbon fiber reinforced aluminium hybrid foam sandwich structure
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-18
    Ashutosh Pandey; Dilip Muchhala; Rajeev Kumar; Sriram S; A.N. Ch Venkat; D.P. Mondal
    更新日期:2019-12-18
  • Design strategy for optimising weight and ballistic performance of soft body armour reinforced with shear thickening fluid
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-17
    Mukesh Bajya; Abhijit Majumdar; Bhupendra Singh Butola; Sanjeev Kumar Verma; Debarati Bhattacharjee

    This study presents some soft armour panel design strategies using shear thickening fluid reinforced Kevlar® fabric. The effect of size of silica nano and sub-micron particles on the ballistic performance of soft body armour panels against the small arms ammunition (velocity ∼ 430 ± 15 m/s) has been analysed. Shear thickening fluids (STFs), namely STF-500 and STF-100, were prepared using silica particles of 500 nm and 100 nm sizes, respectively, and dispersing them in polyethylene glycol (PEG) 200. Kevlar® fabrics were impregnated with both the STFs. Multiple layers (20–24) of fabrics were stitched to prepare 13 soft armour panels which were evaluated for back face signature (BFS) against 9 × 19 mm lead core bullet. Soft armour panels comprised of fabrics impregnated with STF-500 yield lower BFS than the respective panels comprised of fabrics impregnated with STF-100. This study also reveals that STF impregnation of Kevlar® fabrics can reduce the BFS by 2.5 mm–2.8 mm while keeping the areal density of the panel same (5 kg/m2). The areal density of soft armour panel can be reduced further by 10% (4.5 kg/m2), while keeping the BFS comparable or lower than that of a STF impregnated homogenous panel, by judiciously placing the STF impregnated fabrics at the rear side while neat fabrics are placed at the strike face of the panel. STF impregnated panels are found to stop the impacting bullet earlier than that by neat panel.

    更新日期:2019-12-18
  • Impact and post-impact properties of multiscale carbon fiber composites interleaved with carbon nanotube sheets
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-17
    W. Xin; F. Sarasini; J. Tirillò; I. Bavasso; F. Sbardella; L. Lampani; I.M. De Rosa

    The effects of the integration of continuous sheets of randomly oriented multi-walled carbon nanotubes on the low velocity impact behavior of cross-ply carbon/epoxy laminates have been investigated. Three different energy levels were used, namely 5 J, 10 J, and 20 J and significant reductions in delaminated area in the range 11%–39% compared to the baseline laminates were achieved by incorporating interleaves at each 0/90 interface. This resulted in a better flexural damage tolerance of modified laminates. The combination of ultrasonic C-scans, profilometry, and scanning electron microscopy showed that interlaminar crossing between CNT sheets and carbon fibers occurred in modified laminates and that nanotube pull-out, bridging and improved fiber/matrix adhesion are the mechanisms responsible for the enhanced impact performance.

    更新日期:2019-12-18
  • Fabrication of hybrid composite T-Joints by Co-Curing with 3d printed dual cure epoxy
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-17
    Vera Dahmen; Alec J. Redmann; Johannes Austermann; Adam L. Quintanilla; Sue J. Mecham; Tim A. Osswald

    A 3D printed dual cure epoxy is evaluated as a bonding material for composite T-joint structures and compared with other traditional bonding materials by mechanical testing. The epoxy is processed in two steps. First, it is 3D printed using Digital Light Synthesis (DLS), a vat photopolymerization process, resulting in semi-rigid, but only partially cured part. This part is then integrated with pre-impregnated fiber reinforced epoxy resin sheets and co-cured in a second, thermally activated, stage. The bonding strength of the 3D printed epoxy is first investigated by single lap-shear joints and is then implemented in the manufacturing of composite T-joints. The T-joints utilizing 3D printed epoxy as a bonding material show sufficient joint strength in tensile pull-out tests when compared to other common bonding methods. In addition, the 3D printed joints provide a highly reproducible, defect-free bond with improved geometric accuracy. This technology enables the ability to manufacture hybrid composite structures with decreased manufacturing costs due to fewer fixtures, shorter manufacturing times, and a reduction in defects. Furthermore, these adhesive parts can utilize the design freedom of 3D printing by including intricate internal geometries, such as lattice structures, textures, or channels.

    更新日期:2019-12-18
  • A novel detailed analytical approach for determining the optimal design of FRP pressure vessels subjected to hydrostatic loading: Analytical model with experimental validation
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-17
    Mohammad Hadi Hajmohammad; Ali Tabatabaeian; Ahmad Reza Ghasemi; Fathollah Taheri-Behrooz

    A new practical analytical approach has been developed in order to reach the optimal fiber orientation in design of fiber reinforced polymer pressure vessels (FRPPVs) subjected to hydrostatic pressure. The method consists of analytical solutions along with optimizing process in which different decisive factors such as buckling pressure, weight, failure mode of fiber and matrix, thickness, number and angle of layers are considered as problem constraints. In analytical part, besides the buckling analysis, Tsai-Wu and Hashin failure criteria are employed to analyze the failure mode of the structure. Then, the genetic algorithm (GA), as a robust optimization method, is applied to achieve the optimal orientation pattern with minimum weight and maximum buckling load. In addition, the impact of mapped fitness function in optimization process is exclusively analyzed. Next, to validate the reliability and effectiveness of the proposed approach, two different experimental methods including the strain gauge and volume control methods are performed and measured buckling pressure is compared with the analytical results. The results indicated that using the proposed approach, critical buckling load increases by 40% while the weight is reduced by 15%, simultaneously.

    更新日期:2019-12-18
  • Experimental investigation of adhesive fillet size on barely visible impact damage in metallic honeycomb sandwich panels
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-17
    Patrick Kendall; Mengqian Sun; Diane Wowk; Christopher Mechefske; Il Yong Kim

    Aluminum hexagonal honeycomb panels are commonly used in the aerospace industry to reduce weight due to their high stiffness to mass ratio. The panels are commonly involved in incidents where they are dented in the out-of-plane direction which causes plastic deformation in the face-sheet and buckling collapse of the thin repeating cell-walls in the core. This paper investigates the responses to barely-visible-impact-damage (BVID) in aluminum honeycomb sandwich panels in the out-of-plane direction with attention to the structural adhesive. The structural adhesive forms a fillet shape between the face-sheet and the aluminum core during the curing process and in some cases can encompass over 50% of the honeycomb core thickness. The adhesive fillets become stiff after curing and are able to brace the thin metallic cell-walls and prevent buckling in sections of the core enclosed in adhesive. It was shown that larger fillets cause the damage to occur deeper in the core. Force-displacement data collected from quasi-static experiments showed that as the amount of adhesive used in honeycomb panels was increased, the peak force required to produce a specified maximum dent depth increased as well. Absorbed energy positively correlated with an increasing quantity of adhesive; showing improvements of up to 50% when comparing panels with the largest amount of adhesive and no adhesive. This paper provides relationships between the quantity of adhesive used to fabricate metallic honeycomb sandwich panels and the damage resistance and energy absorption under BVID conditions.

    更新日期:2019-12-18
  • Investigating the effects of liquid-plasma treatment on tensile strength of coir fibers and interfacial fiber-matrix adhesion of composites
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-17
    Andi Erwin Eka Putra; Ilyas Renreng; Hairul Arsyad; Bakri Bakri

    The liquid-plasma treatment based on microwave plasma in the liquid was used to treat coir fiber in this study. The effects of such treatment on tensile properties of coir fiber and its compatibility with the epoxy matrix were investigated. Water and sodium bicarbonate (NaHCO3) solution was used as a medium in this treatment. Tensile properties and interfacial shear strength (IFSS) between coir fiber and epoxy resin were determined with single fiber tensile and pull-out tests respectively. Fourier transform infrared spectroscopy, scanning electron microscope and X-ray diffraction were used to characterize the alteration of treated coir fibers. The results show that tensile strength of coir fibers slightly reduce after liquid-plasma treatment with both water and sodium bicarbonate medium except on 12 wt% sodium bicarbonate solution medium for 5 min exposure time. Meanwhile, the interfacial shear strength of coir fiber-epoxy matrix is obtained improvement after water and sodium bicarbonate medium treatment due to good interfacial adhesion between fiber and matrix which could be influenced by micropores on fiber surfaces leading to interlocking adhesion.

    更新日期:2019-12-18
  • 更新日期:2019-12-18
  • Compressive behavior of stretched and composite microlattice metamaterial for energy absorption applications
    Compos. Part B Eng. (IF 6.864) Pub Date : 2019-12-17
    Mahmoud M. Osman; Mostafa Shazly; Ehab A. El-Danaf; Parastoo Jamshidi; Moataz M. Attallah

    A new proposed truss lattice metamaterial is introduced and compared with the conventional octet truss lattice (OTL) material with regards to specific energy absorption (SEA) and energy absorption efficiency (EAE). The proposed lattice architecture resembles the Face-Centered Cubic (FCC) metamaterial with a mesostructural unit cell with an aspect ratio of 1:1:2, referred to as the stretched cell lattice (SCL). SCL and OTL samples were fabricated from stainless steel 316L by selective laser melting (SLM). Quasi-static compression experiments on the SLM fabricated metamaterials revealed an unstable twisting deformation mode for the SCL, whereas a stable crushing behavior was observed for the OTL. SCL samples provided higher SEA and EAE than OTL by 26% and 17%, respectively. Additionally, it was shown analytically, numerically and experimentally that the yield strength of the proposed SCL is ∼80% higher than that of the OTL metamaterials of the same base material and relative density. A hybrid composite lattice structure based on acrylic matrix and the additively manufactured microlattice metamaterials was produced to enhance the struts buckling resistance. The hybrid composite showed a 47% higher specific strength while the SEA and EAE dropped by 31.5% and 30.7%, respectively, when compared to the bare stainless steel microlattice. Dynamic compression experiments using Split Hopkinson Pressure Bar (SHPB) at strain rates in the order of 103/s demonstrated a similar deformation plateau as the static compression experiments with a dynamic increase factor (DIF) of ∼1.3 for the bare stainless steel metamaterials and ∼2 for the acrylic-stainless steel hybrid composite material.

    更新日期:2019-12-18
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