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Composites Part A : Applied Science and Manufacturing
Journal Prestige (SJR): 1.539
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  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1359-835X
Published by Elsevier Homepage  [3181 journals]
  • Recyclable and self-healing rubber composites based on thermorevesible
           dynamic covalent bonding
    • Abstract: Publication date: Available online 19 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Zhixin Jia, Shuli Zhu, Yongjun Chen, Wenqiang Zhang, Bangchao Zhong, Demin Jia Commercial ethylene propylene diene monomer (EPDM) rubber grafted with maleic anhydride (EPDM-g-MA) was thermoreversibly crosslinked by silane modified silica. EPDM-g-MA was first modified with furfurylamine to obtain furan functionalized EPDM (EPDM-g-FA) which was then crosslinked with 3-methacryloxypropyltrimethoxysilane (as electron-poor agent) modified silica via a Diels-Alder reaction. The as-formed rubber network could be broken at high temperature and reconstructed by thermal annealing, which were proven by differential scanning calorimetric analysis and solubility testing. The mechanical strength of the resulting EPDM/silica composites could be tailored by the amount of modified silica and were superior to the previously reported EPDM rubber crosslinked by low molecular organic agents. More importantly, the rubber composites showed good thermal reprocessability and self-healing behavior, by which the crosslinked composites could be recycled to use with comparable mechanical property as the original composites.
  • Experimental comparative study of the variants of high-temperature
           vacuum-assisted resin transfer moulding
    • Abstract: Publication date: Available online 19 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Masoud Bodaghi, Ricardo Costa, Rui Gomes, João Silva, Nuno Correia, Fernando Silva A considerable collection of VARTM choices for composite manufacturing techniques can be both found in literature as well as in industry. Each manufacturing process provides different benefits that must be carefully considered depending on the final application of the desired composite. Here, we present a performance comparison in terms of process effectiveness related to fibre volume fraction, the magnitude of thickness variation, and void contents of 16 laminated composites manufactured by different variants of VARTM (DBVI, VAP, and CAPRI) as well as HIPRTM. Non-crimp carbon textile reinforcements and five-harness satin woven carbon textile reinforcements with a PRISM® EP2400 resin system as base constituents are used to produce composite panels. After manufacturing 16 composite panels, an evaluation of the pros and cons of the processing vs properties/performance obtained with each of them is discussed.
  • Highly Thermally Conductive Phase Change Composites for Thermal Energy
           Storage Featuring Shape Memory
    • Abstract: Publication date: Available online 18 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Fubin Luo, PinPing Yan, Qingrong Qian, Hongzhou Li, Baoquan Huang, Qinghua Chen, Kun Wu, Mangeng Lu Highly thermally conductive form-stable phase change materials (PCMs) possessing shape memory are designed based on covalent-noncovalent interpenetrating polymer network and boron nitride. The matrix network relies on the composition of two functional species, cured mesogenic epoxy (EO) and polyethylene glycol (PEG). It is demonstrated that the covalent network of EO can trap PEG by forming hydrogen bond with PEG chains. On the basis of EO/PEG networks, by incorporating boron nitride, the thermally conductivity of the PCMs can reach to 2.962 W m-1 K-1. The prepared composites show satisfied thermal energy storage capability and good shape stability when undergo long time heating at 80 °C. In addition, the prepared composite exhibits excellent shape memory function. Diverse functions of the PCMs might produce new applications in thermal energy storage or thermal management fields.
  • Mechanical characteristics of tunable uniaxial aligned carbon nanotubes
           induced by robotic extrusion technique for hydrogel nanocomposite
    • Abstract: Publication date: Available online 17 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Weiwei Zhao, Sanming Hu, Zhijun Shi, Tommaso Santaniello, Cristina Lenardi, Jin Huang The utilisation of additive manufacturing technique for producing soft hydrogel nanocomposites could enable extraordinary advances in controlling of the material’s structure at microscale. A soft gel-printing based on 2-hydroxyethyl methacrylate (HEMA)-based gelation system with embedded uniaxial aligned carbon nanotubes (CNTs), was proposed in this paper. Shear-induced alignment determines the uniform orientation of CNTs during the gel-printing process, thereby introducing tunable mechanical anisotropy into the printed nanocomposite products. Herein, mechanical characterisation in terms of uniaxial tension, dynamic cyclic tension, and numerical simulations have been implemented on the printed samples. The numerical modelling findings, verified by the experimental observations, confidently confirm that the orientation of CNTs significantly impacts the mechanical properties of the nanocomposite, i.e. the ultimate strength, degree of viscoelasticity and strain-rate-sensitivity. Both the gel-printing technique and the anisotropic PHEMA-CNTs nanocomposite will ultimately assist to the rapid manufacture of diverse applications such as flexible electronics or tissue engineering.Graphical abstractGraphical abstract for this article
  • A microstructures generation tool for virtual ply property screening of
           hybrid composites with high volume fractions of non-circular fibers -
    • Abstract: Publication date: Available online 16 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): M. Herráez, J. Segurado, C. González, C.S. Lopes Within the framework of computational micromechanics (CMM), a simulation toolset is being developed to predict the mechanical behavior of fiber-reinforced polymers from the measured properties and spatial distribution of the different phases and interfaces in the composite. Towards this end, a numerical methodology is proposed herein for the generation of 2D periodic microstructures with arbitrary fiber geometries. A major advantage of the approach presented in this work is the ability of generating high volume fractions of non-circular fibers very efficiently. The underlying algorithm is based on the minimization of fiber overlapping by dynamic translation and rotation of the fibers until intersections are eliminated. The randomness of the microstructures obtained is assessed by means of multiple spatial descriptors.
  • Simultaneously improving mode I and mode II fracture toughness of the
           carbon fiber/epoxy composite laminates via interleaved with uniformly
           aligned PES fiber webs
    • Abstract: Publication date: Available online 15 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Chao Cheng, Zhengguo Chen, Zhuang Huang, Chenyu Zhang, Rogers Tusiime, Jinli Zhou, Zeyu Sun, Yong Liu, Muhuo Yu, Hui Zhang In this work, a uniformly aligned polyethersulfone (PES) fiber web was designed and fabricated by the melt-spinning PES yarns. Such fiber web was adopted as an interleave to simultaneously improve both mode I and mode II fracture toughness of the carbon fiber/epoxy composite, addressing the issue of transforming the thermoplastic component into a well-controlled uniform and ordered phase structure without being influenced by the liquid forming process. The dissolution behaviors of the PES filaments in the epoxy resin were studied by the optical microscopy with a hot stage. The results indicated that the PES filaments were not dissolvable at the temperature of the resin infusion process, but could be dissolved during the curing process of the epoxy resin in a well controllable way and period. Both the mode I and mode II interlaminar fracture toughness of the composites were investigated as a function of areal densities of the PES fiber webs (7.3, 14.7, 21.2 and 28.3 gsm) carefully. A maximum enhancement up to 120% and 68.8% on mode I and II fracture toughness, respectively was obtained with the introduction of the 28.3 gsm-PES fiber web compared to the laminates without interleaves. Analysis of the fracture surfaces of the laminates elucidated that the distinctive improvement of the interlaminar fracture toughness could be attributed to the characteristic interlaminar structures induced from the phase separation of PES in epoxy resin. Moreover, the interleaved laminates displayed an increase of 18.2% and 43.8% for the interlaminar shear strength (ILLS) and compression-after-impact (CAI) properties, respectably. The tensile and flexural properties of the composite were thereafter explored which indicated slightly enhancement on the strengths.
  • Gradient nanocomposite with metastructure design for broadband radar
    • Abstract: Publication date: Available online 15 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Qunfu Fan, Xuezhao Yang, Hongshuai Lei, Yayun Liu, Yixing Huang, Mingji Chen Absorbers with gradient or stepwise gradient design have been demonstrated to be very beneficial for broadband radar absorption. However, it is still rather difficult to achieve strong absorption at low frequencies such as 2GHz by a thin gradient medium absorber. In this study, metastructure design is introduced to a stepwise gradient nanocomposite containing flaky carbonyl iron power (FCIP) and graphene nanosheet (GNS) as fillers, in order to obtain a thin and ultra-broadband radar absorber. The matrix of the nanocomposite is hybrid of cyanate ester (CE) and Bisphenol-A based epoxy (E51). The absorption band of the fabricated 5mm thick nanocomposite covers the full measured frequency band (2GHz-18GHz, 26.5GHz-40GHz) below -10dB, except for the range of 5.7GHz-7.6GHz (below -9dB).
  • A Novel Composite Negative Stiffness Structure for Recoverable Trapping
    • Abstract: Publication date: Available online 15 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Shuai Chen, Bing Wang, Shaowei Zhu, Xiaojun Tan, Jiqiang Hu, Xu Lian, Lianchao Wang, Linzhi Wu Negative stiffness (NS) structures, as hopeful metamaterials, are potential in the energy absorption (EA) field. However, low specific energy absorption (SEA) limits its engineering application. In this paper, a novel reusable composite NS structure composed of Two-material systems is proposed and investigated. It is potential to be used in shock isolation, vibration control and deployable structure. Specimen was fabricated by additive manufacturing technology. Mechanical properties of this structure are studied with a combination of compression tests and simulations. Repeatability of the structure is then verified through cyclic compression. Besides, plate-impact tests were also carried out to study the cushion performance of this structure. The results of the impact tests reveal that the composite NS structure has good cushion performance by adjusting the threshold of acceleration response amplitude and completely reusable when the snap-through behavior occurs.
  • 2D Ti3C2Tx MXene/Polyvinylidene fluoride (PVDF) nanocomposites for
           attenuation of electromagnetic radiation with excellent heat dissipation
    • Abstract: Publication date: Available online 13 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Krishnamoorthy Rajavel, Suibin Luo, Yanjun Wan, Xuecheng Yu, Yougen Hu, Pengli Zhu, Rong Sun, Chingping Wong The present study deals with novel, and cost-effective preparation of 2D MXene (Ti3C2Tx) filled polyvinylidene fluoride (PVDF) polymer nanocomposite for the attenuation of electromagnetic interference (EMI). The obtained nanocomposite showed remarkable shielding effectiveness (SE) of 48.47 ± 3.5 dB for 22.55 vol% filler contents at a thickness of 2 mm. Formation of conducting network along with the assembly of micro capacitor network preserved for its high EMI shielding performance. The absorption dominated EMI shielding mechanism explained by the strong resonance, and interfacial polarization favors the loss of incident EM energy confirmed dielectric measurements. Besides, the enhanced thermal conductivity of MXene-PVDF nanocomposites about 0.767 ± 0.034 Wm-1K-1 at 22.55 vol% filler content depicts that a large amount of incident EM wave attenuated majorly by dielectric components which would be dissipated as heat quickly. The fabricated MXene-PVDF nanocomposites could be a potential candidate for EMI shielding materials and promising multifaceted electronic utilization.
  • Effect of metal-based nanoparticles decorated graphene hybrids on
           flammability of epoxy nanocomposites
    • Abstract: Publication date: Available online 13 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ehsan Naderi Kalali, Wenwen Guo, Xin Wang, Weiyi Xing, Lei Song, Yuan Hu To overcome the flammability of epoxy resins (EPs), metal-based nanoparticles decorated reduced graphene oxide (rGO) hybrids including Ag@rGO, Cu2O@rGO and TiO2@rGO, were synthesized through microwave irradiation technique and subsequently incorporated into EPs. The structure and morphology of the metal-based nanoparticles decorated rGO hybrids were characterized by XRD, XPS, TEM and SEM, which confirmed successful synthesis of the hybrid materials. The metal-based nanoparticles were uniformly deposited to the rGO nanosheets, which could avoid re-stacking of graphene nanosheets. The addition of metal-based nanoparticles decorated rGO hybrids significantly diminished the flammability of epoxy nanocomposites. Specifically, the Cu2O@rGO/EP nanocomposite showed 50% and 29% reduction in peak heat release rate and total smoke production, respectively. The reduced flammability was attributed to the improved char yield that restrained the heat and smoke release during combustion. It is prognosticated that metal-based nanoparticles decorated graphene hybrids will provide an efficient solution to improve fire safety of polymeric materials.
  • Studies on the dimensional stability and mechanical properties of
           nanobiocomposites from polyamide 6-filled with biocarbon and nanoclay
           hybrid systems
    • Abstract: Publication date: Available online 13 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Mohamed Abdelwahab, Amandine Codou, Andrew Anstey, Amar K. Mohanty, Manjusri Misra Polyamide 6 (PA 6) nanobiocomposites were produced using a novel hybrid reinforcement strategy, utilizing a combination of biocarbon and nanoclay. Using melt extrusion and injection moulding, composites containing 30 wt.% filler were produced with various ratios of nanoclay to biocarbon. The morphology and crystalline structure were studied and revealed the anisotropic nature of the biocomposites. Further investigation of the polymer crystallization by differential scanning calorimetry and wide angle X-ray diffraction revealed that while the fillers did not affect the degree of crystallization, they strongly influenced the orientation of the crystallites. By using hybrid fillers, the coefficient of linear thermal expansion and mechanical properties of the PA 6 biocomposites were improved with the addition of only a small fraction of nanoclay. These injection moulded hybrid nanobiocomposites with ∼ 28.5 wt.% bio-based content had excellent mechanical properties along with improved dimensional stability, and show potential for use in sustainable automotive parts.Graphical abstractGraphical abstract for this article
  • Multilayer WPU conductive composites with controllable electro-magnetic
           gradient for absorption-dominated electromagnetic interference shielding
    • Abstract: Publication date: Available online 11 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): An Sheng, Wei Ren, Yaqi Yang, Ding-Xiang Yan, Hongji Duan, Guizhe Zhao, Yaqing Liu, Zhong-Ming Li A well-designed multilayered waterborne polyurethane (WPU) shielding composites with absorption-dominated shielding feature are realized by constructing a controllable electro-magnetic gradient. Using the layer-by-layer casting method with reasonable arrangement of Fe3O4@rGO and MWCNT nanofiller, an ordered multilayer shielding network can be constructed to provide the WPU composites with positive electrical conductivity gradient and negative magnetic gradient. Hence, the penetrating microwave would undergo a particular “absorption-reflection-reabsorption” process and interface polarization loss induced absorption process between impedance matching layer and high conductive layer, leading to rather low microwave reflection with effect electromagnetic interference shielding effeteness (EMI SE). With the increase of electro-magnetic gradient, the EMI SE of the Fe3O4@rGO/MWCNT/WPU composites reaches 35.9 dB, while the power coefficient of reflectivity can be significantly decreased to 0.27. This work offers a feasible strategy for designing absorption-dominated shielding material with tunable electromagnetic performance that suitable for next-generated smart electronic devices.
  • A Constitutive Model for Fiber Kinking: Formulation, Finite Element
           Implementation, and Verification
    • Abstract: Publication date: Available online 9 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Andrew C. Bergan, Miguel Herráez, Carlos González, Cláudio S. Lopes A new mesoscale material model is proposed to analyze structures that fail by the fiber kinking damage mode. The model is formulated following the fiber kinking theory such that the interaction of shear nonlinearity and fiber rotation are tracked throughout the loading history. The model is implemented as a user-defined material in a commercial finite element code. A decomposition algorithm is introduced in the finite element implementation to decouple the mesh size and kink band width. To evaluate the assumptions of the mesoscale model, the results were compared with those of a high-fidelity micromechanical model. A direct comparison between the two models shows remarkable correlation, providing evidence that the key features of the fiber kinking phenomenon are appropriately accounted for in the mesoscale model. The model is demonstrated for a simple unnotched compression configuration. The results show that the model is successful at representing the kinematics of fiber kinking.
  • A review on alfa fibre (Stipa tenacissima L.): From the plant architecture
           to the reinforcement of polymer composites
    • Abstract: Publication date: January 2020Source: Composites Part A: Applied Science and Manufacturing, Volume 128Author(s): Fatima Ezzahra El-Abbassi, Mustapha Assarar, Rezak Ayad, Alain Bourmaud, Christophe Baley The automotive and aeronautic industries have become strategic sectors for North African countries. However, the future growth of these sectors will likely depend on the availability of raw materials such as plant fibres to reinforce polymers. In the framework of this paper, we reviewed the research that focused on alfa fibres, which are deemed to be one of the most available fibres in the Mediterranean area. This plant also plays an essential role in protecting the Mediterranean countries from desertification and desert encroachment. Throughout this review, we discussed and expounded the morphological, chemical compositions and the mechanical properties of the alfa fibres and we compared them to other plants fibres. Moreover, we surveyed several academic research works that used different alfa fibres as reinforcement of thermoset and thermoplastic matrices. In particular, we outlined that alfa fibre can constitute a potential reinforcement of polymer matrices in the North Africa countries.
  • Form-Stable Phase Change Materials Based on Delignified Wood Flour for
           Thermal Management of Buildings
    • Abstract: Publication date: Available online 6 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Le Cheng, Jiachun Feng In this work, form-stable phase change composites (PCCs) was prepared based on wood flour (WF), the by-product of timber industry, via delignification and impregnation with myristyl alcohol (MA). After delignification, the micro-channel structure inherited from wood was still maintained and unblocked in delignified wood flour (dWF), which are beneficial to accommodate and restrict solid-liquid phase change materials (PCMs). The dWF/MA PCCs exhibit excellent leakage-proof properties even at temperature much higher than the melting point of MA and high phase change enthalpy. The dWF/MA PCCs were further used to fabricate composite boards by bonding with urea-formaldehyde (UF) resin. The temperature management effect of dWF/MA/UF boards was tentatively demonstrated through constructing building models and measuring the inner temperature-time curves. This work provides a promising way to fully utilize and functionalize WF and broad its application in energy-related areas.Graphical abstractBy taking advantages of the good processing characteristic and micro-channels structures, wood flour was used as raw materials to prepare form-stable phase change composite with high thermal storage capacity as well as thermal and shape stability by delignification and impregnation with liquid myristyl alcohol.Graphical abstract for this article
  • Electrospun Submicron NiO Fibers Combined with Nanosized Carbon Black as
           Reinforcement for Multi-functional Poly(lactic acid) Composites
    • Abstract: Publication date: Available online 6 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Lu Zhang, Wei Liu, Xin Wen, Jiayin Chen, Chenshou Zhao, Miguel Castillo Rodríguez, Lingwei Yang, Xiu-Qin Zhang, Rui Wang, De-Yi Wang From the point of designing fiber reinforced multi-functional polymer composites, porous submicron nickel oxide (NiO) fibers were fabricated via electrospinning and subsequent pyrolysis process. Combined with nanosized carbon black (CB), the influences of NiO fibers on the mechanical properties and flame retardancy of polylactide (PLA) composites were investigated. The results showed the electrospun NiO fibers imparted higher tensile strength and modulus to PLA composites. With the increase of NiO fiber content in PLA composites, the Young’s modulus, storage modulus from dynamic mechanical analysis and elastic modulus derived from nanoindentation test showed similar increasing trends. In addition, compared with commercial NiO particles, NiO fibers exhibited a better flame retardant effect, which was attributed to the formation of continuous and intact char layer network. The proposed combination of electrospun NiO fibers and nanosized CB in PLA matrix is expected to inspire new strategies to prepare multi-functional fiber reinforced polymer matrix composites.
  • High Thermal Conductive Epoxy Based Composites Fabricated by
           Multi-Material Direct Ink Writing
    • Abstract: Publication date: Available online 4 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Junchao Liu, Yufeng Guo, Chuanxin Weng, Hui Zhang, Zhong Zhang Thermal management is of importance to microelectronic industry. Owing to both excellent thermal conduction and electrical insulation, hexagonal boron nitride (BN) platelets are the widely-used thermal conductive fillers in polymers. Adding high content of BN can endow polymers high thermal conductivity, but in most cases, destroy the flexibility, failure strength as well as processability of the polymers significantly. Here, we report a multi-material 3D printing technique to prepare high thermal conductive epoxy based composites, by which BN platelets were assembled tegother in heat-conducting phase to form the dense, continuous thermal pathway. The BN platelets show excellent alignment along printing direction in epoxy matrix due to the shear-inducing effect of printing. The composites at filler loading of 20 wt% exhibit the thermal conductivity of 2.52 W·m-1·K-1 along printing direction. The thermal conductivity of the composites is in good agreement with the prediction of parallel model. It indicates that the composites with specific thermal conductivity can be prepared by tailoring the printing ratio of the heat-conducting phase to the matrix phase. Mechanical and insulating performance of the composites maintain good enough as well.
  • Multifunctional light-responsive graphene-based polyurethane composites
           with shape memory, self-healing, and flame retardancy properties
    • Abstract: Publication date: Available online 4 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Weining Du, Yong Jin, Shuangquan Lai, Liangjie Shi, Yichao Shen, Heng Yang It is a challenge to manufacture light responsive polymer composite that possesses shape memory, self-healing, and flame retardancy capacities. Herein, multi-functionalized graphene oxide (mfGO) wrapped with nitrogen-, phosphorus-, and silicon- containing units was prepared via in-situ polymerization and subsequently was incorporated into a diselenide-containing polyurethane (dPTD) matrix to fabricate composite. The successful functionalization of mfGO was initially confirmed by a series of measurements. Taking advantage of the crystallization-induced and photo-thermal effects of mfGO as well as the dynamic exchange characteristic of diselenide bonds, the dPTD-mfGO2 composite containing 2 wt% of mfGO exhibited admirable shape memory and self-healing behaviors under visible-near infrared light within 3 min, and its shape memory characteristics and healing efficiencies were kept above 90% and 76% after three cycles, respectively. Further combustion experiments demonstrated that dPTD-mfGO2 composite showed superior LOI (24.9%) and UL-94 rating (V-2) without flaming drips, owing to the synergistic catalyzing carbonization and barrier effect of mfGO. Additionally, the dPTD-mfGO2 composite possessed an improved water contact angle of 109.5°. These findings suggest that the introduction of 2 wt% mfGO to the dPTD matrix can synergistically improve the toughness, shape memory, self-healing, flame retardancy, and water resistance as compared with the neat dPTD. This work provides a promising pathway to fabricate stimulus-responsive composite materials with versatile functions.
  • Computationally efficient method of tracking fibres in composite materials
           using digital image correlation
    • Abstract: Publication date: Available online 4 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): K. Amjad, W.J.R. Christian, K. Dvurecenska, M.G. Chapman, M.D. Uchic, C.P. Przybyla, E.A. Patterson A computationally efficient method based on digital image correlation (DIC) has been introduced in this paper for fast and accurate characterisation of fibre orientation fields from a series of optical mosaics of a continuous fibre-reinforced composite (CFRC) specimen, which were obtained using a well-established automated serial sectioning technique. The newly developed method has the capability of determining fibre paths from the sequence of mosaics in scenarios where the serial section spacing between the adjacent mosaics is atypically large, resulting in shifts in the fibre locations on the order of 90 pixels or twelve fibre diameters. The performance of the proposed method was quantitatively compared with a state-of-the-art fibre-tracking algorithm based on a Kalman filter, by applying them to the mosaic sequences from two CFRC material specimens. It was demonstrated from the fibre-tracking results that the proposed DIC-based method outperformed the Kalman filter algorithm in terms of both reliability and speed.
  • A thick-walled sheet moulding compound automotive component: manufacturing
           and performance
    • Abstract: Publication date: Available online 4 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): L.M. Martulli, Thomas Creemers, Erich Schöberl, Nicholas Hale, Martin Kerschbaum, Stepan V. Lomov, Yentl Swolfs Carbon Fibre Sheet Moulding Compounds (CF-SMCs) are lightweight materials very suitable for automotive parts. So far, their use was limited to thin components. This work presents a feasibility study on the compression moulding of a thick-walled SMC component, with a compound of randomly oriented chopped carbon fibre tapes. Bending tests were used to evaluate the effects of the manufacturing conditions on the mechanical performance. The choice of the charge pattern configuration played the paramount role in the final part performance, especially via the creation of weld surfaces, leading to a maximum strength difference of over 400%. The moulding temperature, pressure and cooling method showed no statistically significant influence on both strength and stiffness of the part. The results of this work can be used as a starting point in the design of manufacturing processes for thick SMC components.
  • Interlayer Controllable of Hierarchical MWCNTs@C@FexOy Cross-linked
           Composite with Wideband Electromagnetic Absorption Performance
    • Abstract: Publication date: Available online 4 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Guanglei Wu, Zirui Jia, Xinfeng Zhou, Guozhe Nie, Hualiang Lv Magnetic multi-walled carbon nanotube (MWCNTs) hybrids are a promising high-performance electromagnetic (EM) absorber with the merits of wideband, thin thickness and lightweight etc. Even so, it remains a challenge to achieve a wideband absorption under a thickness (d
  • Lightweight, Flexible and Superhydrophobic Composite Nanofiber Films
           Inspired by Nacre for Highly Electromagnetic Interference Shielding
    • Abstract: Publication date: Available online 4 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ting-Ting Li, Yanting Wang, Hao-Kai Peng, Xuefei Zhang, Bing-Chiuan Shiu, Jia-Horng Lin, Ching-Wen Lou Inspired by the hierarchical structure of nacre, this study prepared a lightweight, flexible, and superhydrophobic polyacrylonitrile (PAN)@SiO2-Ag composite nanofibrous film with high performance electromagnetic-interference shielding via electrospinning. SiO2 incorporated into PAN electro-spun films provided the adhesion site for Ag nanoparticles (AgNPS). AgNPS were then deposited onto the surface of PAN@SiO2 electrospinning nanofibers via facile wet electroless deposition, thus endowing the resulting nanofibers with a core-shell structure. After finishing with a PTDT agent, PAN@SiO2-Ag composite nanofiber films had super hydrophobic property, and their water contact angle reached 156.99°. This scenario also presented high conductivity (approximately 17788 S/m), average shielding effectiveness (SE), specific SE (SSE), and SSE/t, achieving 82 dB, 367 dB cm3g−1 and 73,478 dB cm2g− 1, respectively. This study provides an easy method to prepare bioinspired composite films with high conductive and electromagnetic shielding and high potential applications, such as in wearable and flexible sensors.
  • Hydroxyapatite/polyurea nanocomposite: preparation and multiple
           performance enhancements
    • Abstract: Publication date: Available online 2 November 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Tao Zhang, Wei Cai, Fukai Chu, Feng Zhou, Shuen Liang, Chao Ma, Yuan Hu In order to obtain polyurea (PUA) with better mechanical properties, hydroxyapatite (HAP)/PUA nanocomposites were prepared by the in-situ polymerization of polycarbodimide modified diphenylmethane diisocyanate (MDI-100L) covalently connected onto the HAP and Poly(tetramethylene oxide-di-p-aminobenzoate) (PTMO, P1000). The performance enhancements of nanocomposites were investigated through observing dispersion and interface interactions. As for the mechanical performance, tensile testing results indicated that the PUA/HAP nanocomposite with 0.2 wt% HAP nanorods exhibited improvements in tensile stress (52.4%). Scanning electron microscope (SEM), attenuated total reflection flourier transformed Infrared (ATR-FTIR) and X-ray diffraction (XRD) indicate that dispersion of HAP and the hydrogen bonds between the HAP nanorods and PUA are the significant factors for mechanical strength developing of PUA composites. Moreover, the self-stiffness of PUA was effectively suppressed by the incorporated HAP nanorods and decreased with the increase of HAP contents. Therefore, herein we provide useful information for the development of PUA/HAP composites.
  • Sustainable Biocomposites from Nylon 6 and Polypropylene Blends and
           Biocarbon – Studies on Tailored Morphologies and Complex Composite
    • Abstract: Publication date: Available online 31 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Amandine Codou, Manjusri Misra, Amar K. Mohanty The ability of irregular and polydisperse sustainable biocarbon (BC) particles to deform a binary immiscible blend in composites formulations was investigated at different particle polarity. Herein, up to 40 wt. % of biocarbon particles with size of ∼ 1.80-2.00 µm were melt-compounded with polyamide 6 (PA6) and polypropylene (PP) at 80/20 and 20/80 (w/w). A high affinity of biocarbon for the PA6 phase over the PP phase was observed and was not affected by the polarity. A critical filling ratio (φBC in PA6 or φPA6+BC in PP) marking the formation of a 3-dimensional percolated network between the particles was estimated at ∼0.26-0.31, yielding a fractal network of dimension df ∼1.7-2.0. This critical ratio was assessed by measuring the droplet size, material viscosity, and yield stress. In addition, a transition from a droplet suspension to funicular morphology was observed at φPA6+BC ∼0.36 in PP. It was furthermore found that solid- or liquid-like behavior in such morphologies was induced by a high or low biocarbon surface functionality as a result of low or high biocarbon pyrolysis temperature. As such this work gives new insight on morphology development and properties of complex composite structures with heterogeneous particles.
  • A Review on the Hybrid Titanium Composite Laminates (HTCLs) with Focuses
           on Surface Treatments, Fabrications, and Mechanical Properties
    • Abstract: Publication date: Available online 30 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): M.E. Kazemi, Logesh Shanmugam, Lei Yang, Jinglei Yang This paper reviews fiber metal laminates (FMLs) with a focus on hybrid titanium composite laminates (HTCLs). FMLs are high-performance hybrid structures based on alternating stacked arrangements of fiber-reinforced polymer composite (FRPC) plies and metal alloy sheets. The mechanical performance potential of FMLs inspired an investigation into new composites, metals, and adhesive systems to further improve their mechanical properties and to reduce the weight of these structures. HTCLs offer better advantages when compared to traditional FMLs and FRPCs, especially in aeronautical, marine, military, and offshore applications both at room and elevated temperatures as well as harsh environmental conditions. They are outstanding in terms of stiffness, yield stress, fatigue, and high-velocity impact properties; however, there are some challenges regarding fabrication, surface treatment, and mechanical properties of such structures, which need to be further addressed. Due to the lack of consolidated research surrounding HTCLs, a review is necessary for effective comparison.
  • Shear deformation and energy absorption analysis of flexible fabric in
           yarn pullout test
    • Abstract: Publication date: Available online 28 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ruixiang Bai, Yu Ma, Zhenkun Lei, Yang Feng, Jianchao Zou, Da Liu The friction level between yarns significantly affects the ballistic performance of flexible fabrics. In this study, single yarn pullout tests of Kevlar 49 plain weave fabric under different preloads and different yarn pullout rates were carried out. The in-plane shear deformation of the fabric was measured using a digital image correlation method to determine the global shear strain and shear modulus. In addition, based on the stick-slip phenomenon in the process of yarn pulling, a bilinear stress transfer model between yarns was developed. The energy absorption mechanism and interface shear stiffness were theoretically analyzed, and the yarn interface parameters were inversely obtained from the experimental data. The analytical results of the proposed stress transfer model are consistent with the experimental load-displacement curve.
  • Simultaneously improved dielectric constant and breakdown strength of
           PVDF/Nd-BaTiO3 fiber composite films via the surface modification and
           subtle filler content modulation
    • Abstract: Publication date: Available online 23 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Zhong Yang, Jing Wang, Yiliang Hu, Chaoyong Deng, Kongjun Zhu, Jinhao Qiu Flexible dielectric capacitors with large energy storage density play key role in modern electronic devices. Ceramic fibers with large dielectric constants are benign candidates to be introduced into the polymer matrix to enhance the energy storage density while guaranteeing the flexibility. In present work, Nd doped BaTiO3 (NBT) fibers with and without dopamine (PDA) coating were successfully fabricated and introduced into the Poly(vinylidene fluoride) (PVDF) matrix. The dielectric constants and breakdown strength were simultaneously enhanced with a small loading of NBT filler. The subtle modulation was then performed around the filler loading at which the large energy density was obtained. With the NBT loading of 2.5 wt% and 4.2 wt%, the maximum energy density of 9.3 and 10.4 J/cm3 were obtained in PVDF/NBT and PVDF/NBT@PDA composites, respectively. Both of experimental results and simulation indicate the effectiveness of dopamine coating on the uniform distribution of electric field and good comparability between the matrix and fillers.
  • Anomalously enhanced toughness of poly (lactic acid) nanocomposites by
           core-shell particles with high thickness soft shell
    • Abstract: Publication date: Available online 23 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Hailing He, Zhiwei Duan, Zhenqing Wang The anomalous improvement in ductility and toughness of biodegradable poly (lactic acid) (PLA) was achieved by incorporating the silica-g-poly(caprolactone-co- lactide) (SiO2-PCLLA) core-shell nanoparticle with high thickness rubber shell. The variation of mechanical properties and toughening mechanism of nanocomposites with rubber shell thickness were investigated via tensile tests and surface morphology observation, X-ray scattering (SAXS) and diffraction (WAXD). The experimental results showed that the core-shell nanoparticle with high thickness rubber shell of 25 nm extremely remarkably improved the ductility and toughness of nanocomposite, about 34 times higher than those of neat PLA, particularly nearly without reducing its strength. This considerable increment of toughness is attributed to that the cavitation occurred in thick rubber shell can induce the intense plastic flow of matrix, forming the fibrillated structure like ‘bamboo joint’. In addition, it was found that the toughening of PLA is not only related to the rubber shell thickness, but also to the added nanofiller content.
  • In situ observation of interactive failure modes in a single-edge notched
           symmetric cross-ply laminate using synchrotron X-ray tomography
    • Abstract: Publication date: Available online 22 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Eonyeon Jo, Sooyoung Lee, Chaeyoung Hong, Wooseok Ji Interactive failure mechanisms of a single-edge notched (SEN) symmetric cross-ply laminate subjected to tensile loading are studied in situ using synchrotron X-ray tomography and a DIC technique at the micro- and macro- scales. The SEN configuration guarantees the repeatability and consistency of the progressive and interactive failure behavior at the two different scales. The evolution of various fracture modes in different layers is observed through synchrotron radiation CT images. Due to the geometrically asymmetric configuration, all the initial cracks sequentially occurring near the notch tip can be captured in a narrow field of view. Stress relaxation due to the subsequent fracture initiations is indirectly captured by measuring the crack lengths and opening displacements from the 3D CT images at different loading steps. The stress relaxation is directly measured by DIC analysis using the macro-scale test data. DIC results show strains relaxed in the region between existing and emerging transverse cracks.
  • Design of network Al2O3 spheres for significantly enhanced thermal
           conductivity of polymer composites
    • Abstract: Publication date: Available online 22 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Yuge Ouyang, Fei Ding, Liuyang Bai, Xiaofei Li, Guolin Hou, Junmei Fan, Fangli Yuan It is of great significance to realize high thermal conductivity of polymer composites, which are used in electronic devices. However, traditional polymer composites exhibit limited thermal conductivity due to high interfacial thermal resistance. Herein, network Al2O3 (N-Al2O3) with multidimensional continuous structures is fabricated by a feasible strategy and first used as fillers for phenolic resin (PR), achieving significantly enhanced thermal conductivity of 4.01 Wm−1 K−1, enhanced by 1800% compared with neat matrix. The unique N-Al2O3 is responsible for the excellent thermal conductivity, which contributes to the continuous thermal transfer pathways with decreased interfacial thermal resistance. Additionally, owing to the interpenetrating structure of N-Al2O3 and PR, composites display improved mechanical properties and thermal stability. Dielectric loss tangent of composites decreases with increasing N-Al2O3, which is unusual and desired for thermal interface materials used in electronic devices. Therefore, our strategy offers new guidelines in fabricating high-quality composites for commercial applications.
  • Preparation and characterization of foamed wheat straw fiber/polypropylene
           composites based on modified nano-TiO2 particles
    • Abstract: Publication date: Available online 22 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Dong Wang, Lihui Xuan, Guangping Han, Andrew H.H. Wong, Qingxiang Wang, Wanli Cheng The nano-TiO2 modified foamed wheat straw fiber/polypropylene (F-WSFs/PP) hierarchical composites were fabricated by a hot-extrusion process. To improve the dispersion of nano-TiO2 and increase the compatibility between WSFs and PP, the WSFs were immersed in 1-5 wt% unmodified and coupling agents (A171 or KH550)-modified nano-TiO2 suspensions by vacuum pressure. The size, crystallinity and composition of modified nano-TiO2 were analyzed by Laser particle size analyzer (LS), XRD and FT-IR. Moreover, the modification mechanism was clarified to understand interface interaction between WSFs and PP. SEM results showed that nano-TiO2 was deposited on the WSFs surfaces. UV-Vis showed that WSFs treated with modified-TiO2 exhibited excellent UV-shielding properties in the range of 100-200 nm. Mechanical testing indicated that WSFs treated with 4% KH550-modified nano-TiO2 exhibited the highest flexural (29.27 MPa), tensile (14.38 MPa), and impact (4.55 KJ/m2) strengths. Overall, the TiO2-KH550 modified F-WSFs/PP composites excellent UV-shielding properties and mechanical strengths.
  • Thermo-mechanical properties of compaction molded cement-based composite
           containing a high volume fraction of phase change material for thermal
           energy storage
    • Abstract: Publication date: Available online 21 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Guochen Sang, Yangkai Zhang, Min Fan, Xiaoyun Du, Hongzhi Cui, Xiaoling Cui, Yiyun Zhu, Qin Zhao This study presents a novel compaction molded composite of sulphoaluminate cement-based thermal energy storage mortar (SCTESM) containing shape stabilized phase change materials (SSPCM) up to 25.9 wt%. A series of tests were conducted to investigate the thermo-mechanical properties of SCTESM. The results show that the thermal conductivity of the compaction molded SCTESM is about 60% higher than that of casting molded one. A mathematical model for thermal conductivity prediction was proposed with a maximum relative error of 5.69%. Furthermore, the thermal penetration depth of SCTESMs was also analyzed, and the thermal penetration depth of the compaction molded samples was over 30% higher than that of casting molded sample of same SSPCM dosage. The mechanical strength determination revealed that compaction molding method can increase the 28-day compressive strength and flexural strength of SCTESM by 28.0% and 40.0% than that of casting molded one with the same SSPCM dosage.
  • Achieving electrical insulation, high thermal conductivity and high
           fracture toughness in polyamide 6/carbon nanofiber composites through the
           interfacial welding effect of elastomer
    • Abstract: Publication date: Available online 21 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Wen-yan Wang, Xiao Ma, De-xiang Sun, Xiao-dong Qi, Jing-hui Yang, Yong Wang Interfacial interaction exhibits important role in determining the performance of polymer composites, especially at high filler content. In this work, illuminated from the braze welding technology that is applied to joint different metals using the welding stick with relatively high plastic deformation ability or high toughness, a new concept of ‘interfacial welding’ was proposed to engineer the strong interfacial interaction of the thermally conductive composites. A commercial elastomer, i.e. anhydride-modified ethylene-based copolymer (AEC), was incorporated into the polyamide 6 (PA6)/carbon nanofibers (CNFs) composites. Due to the presence of the insulating AEC and the stronger interfacial affinity between CNFs and AEC, the ternary PA6/CNF/AEC composite samples showed largely enhanced electrical resistance and comparable thermal conductivity compared with the binary PA6/CNF composite samples. Specifically, largely enhanced fracture toughness was achieved for the ternary composite samples. The concept of ‘interfacial welding’ may be extended to fabricate the other composites with excellent comprehensive performances.Graphical abstractGraphical abstract for this article
  • Synchronously improved electromagnetic interference shielding and thermal
           conductivity for epoxy nanocomposites by constructing 3D copper
           nanowires/thermally annealed graphene aerogel framework
    • Abstract: Publication date: Available online 20 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Xutong Yang, Shuguang Fan, Ying Li, Yongqiang Guo, Yunge Li, Kunpeng Ruan, Shengmao Zhang, Junliang Zhang, Jie Kong, Junwei Gu 3D copper nanowires-thermally annealed graphene aerogel (CuNWs-TAGA) framework is firstly prepared by freeze-drying followed by thermal annealing from CuNWs, graphene oxide (GO) and L-ascorbic acid. Epoxy resin is then poured back into the above 3D CuNWs-TAGA framework to fabricate the CuNWs-TAGA/epoxy nanocomposites. CuNWs with average diameter of about 120 nm and length of approximate 10 μm are successfully prepared. When the mass fraction of CuNWs-TAGA is 7.2 wt% (6.0-1.2 wt% CuNWs-TAGA), the thermal conductivity coefficient (λ) value of the CuNWs-TAGA/epoxy nanocomposites reaches the maximum of 0.51 W/mK. Meantime, the CuNWs-TAGA/epoxy nanocomposites exhibit the maximum electromagnetic interference shielding effectiveness (EMI SE) value of 47 dB and electrical conductivity (σ) of 120.8 S/m, ascribed to perfect 3D CuNWs-TAGA conductive network structures. Meanwhile, the corresponding elasticity modulus, hardness, glass transition temperature (Tg) and heat-resistance index (THRI) of the CuNWs-TAGA/epoxy nanocomposites increase to 4.69 GPa, 0.33 GPa, 126.3°C and 181.7°C, respectively.
  • Locally connected nano-micro two-dimensional fillers in nanocomposites for
           advanced thermal management
    • Abstract: Publication date: Available online 16 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Jialong Li, Jinghua Yin, Xiaoxu Liu, He Zhao, Yanpeng Li, Congcong Zhu, Dong Yue, Jimin Wang, Yu Feng, Bo Su The co-filling of nano-sized 2D-BN pellets and micro-sized 2D-Ag sheets (AgMSs) (2 wt%) was used to improve thermal conductivity (λ) of PVDF-HFP-based composites. The nano-micro co-filled composites simultaneously possess high λ and excellent insulation properties. Compared with the sole-BN filled composites, high λ of the co-filled composites could be realized at relative low filler loading, and a maximal λ of 5.38 W m-1K-1 is achieved in the PVDF-HFP/BN20/Ag2 composite. According to the detailed characterization results, a mechanism related to the construction of locally-connected structures, denser overall microstructure and reduced interfacial thermal resistance in the composites is proposed to be responsible for the enhanced λ and the excellent electrical insulating properties. Moreover, the finite element analysis (FEA) simulation results provide compelling evidence that the co-filled composites exhibit promising potential in thermal management applications. Consequently, this work provides a simple and effective method in fabricating superior thermal conductive yet insulating polymer-based composites.
  • Interleaving light veils to minimise the trade-off between mode-I
           interlaminar fracture toughness and in-plane properties
    • Abstract: Publication date: Available online 15 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): S.M. García-Rodríguez, J. Costa, K.E. Rankin, R.P. Boardman, V. Singery, J.A. Mayugo Interleaving heavy micro-fibre veils, commonly used to improve interlaminar fracture toughness, severely compromises tensile and compressive properties. To reduce the trade-off, this study interleaved two different types of light (4 g/m2) co-polyamide veils into a thin-ply quasi-isotropic baseline laminate. Sub-micron resolution X-ray micro-computed tomography provided insight into the after-manufacturing state of the veil fibres as well as into the fracture process zone of mode-I interlaminar fracture toughness specimens. The veil fibre diameter was the key parameter in determining the tensile properties (the veil with thinner fibres avoided resin accumulation at the interfaces and left the baseline properties unaffected). Both veils decreased the compressive strength by up to 9%. Mode-I crack propagation was controlled by the adhesion between the veil fibres and resin. Veils fibres with the higher adhesion deflected crack propagation to the surrounding 0° plies, which improved mode-I initiation and propagation interlaminar fracture toughness (by 101% and 43%).
  • Study of matrix-filler interaction of polypropylene/silica composite by
           combined infrared (IR) spectroscopic imaging and disrelation mapping
    • Abstract: Publication date: Available online 12 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ryota Watanabe, Aki Sugahara, Hideaki Hagihara, Hiroaki Sato, Junji Mizukado, Hideyuki Shinzawa We demonstrate a Fourier transform infrared (FTIR) spectroscopic imaging combined with two-dimensional (2D) correlation analysis to elucidate matrix-filler interaction of polymer composites. Composite of maleic anhydride grafted polypropylene (MAPP) and silica sphere (SS) was fabricated. The FTIR image and disrelation map derived from sets of FTIR spectra suggest that the maleic anhydride groups in MAPP surround the SS surface and interact with the silanol on the surfaces of SS via hydrogen bonding. This clear link between MAPP and SS indicates that MAPP can be utilized as a suitable amphiphilic compatibilizer for an SS filler when it is mixed with hydrophobic polymer. FTIR imaging analysis was then further extended to categorize the interfacial states of more complicated polymer composites consisting of polypropylene (PP)/SS containing MAPP as a compatibilizer. Probing the interfacial chemical state using FTIR imaging revealed the interaction between MAPP and SS to contribute to improved elastic modulus of PP/MAPP/SS.Graphical abstractGraphical abstract for this article
  • Interlaminar fracture toughness of aerospace-grade carbon fibre reinforced
           plastics interleaved with thermoplastic veils
    • Abstract: Publication date: Available online 9 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Dong Quan, Francesca Bologna, Gennaro Scarselli, Alojz Ivankovic, Neal Murphy This work investigates the toughening performance of thermoplastic veils when used to interlay aerospace-grade CFRPs. Veils based on Polyethylene-terephthalate (PET), Polyphenylene-sulfide (PPS) and Polyamide-12 (PA) fibres (∼10 μm in diameter) were used as interlayers of unidirectional (UD), non-crimp fabric (NCF) and 5-Harness satin weave (5H) carbon fibre/epoxy laminates. During a hot curing process of the laminates, the PET and PPS veils remained in a fibrous form, and the PA veils melted. This resulted in different toughening mechanisms, i.e. interlaying the PET and PPS veils introduced extensive thermoplastic fibre bridging, and adding the PA veils improved the fracture toughness of the epoxy matrix. The different toughening mechanisms of the veils, together with the different fracture mechanisms of the laminates, dramatically affected the toughening levels. In general, the PET and PPS veils were more effective for toughening the UD laminates, and the PA veils were superior for the NCF and 5H laminates.
  • Ultra-thin-ply CFRP Bouligand bio-inspired structures with enhanced
           load-bearing capacity, delayed catastrophic failure and high energy
           dissipation capability
    • Abstract: Publication date: Available online 5 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Lorenzo Mencattelli, Silvestre T. Pinho In this work, we demonstrate for the first time that the inherent low performance to out-of-plane loading of thin-ply Carbon Fibre Reinforced Plastics (CFRPs) can be overcome with tailored bio-inspired Bouligand microstructures. To this end, we designed, manufactured ultra-thin-ply CFRP Bouligand laminates and conducted an original study which combines full-penetration quasi-static indentation tests, in-situ three-point bending tests conducted under a SEM and detailed analytical modelling. We investigated a wide range of mismatch (pitch) angles [2.5°, 5°, 10°, 20°, 45°], showing that decreasing pitch angles simultaneously achieved a larger (i) load-bearing capability, (ii) delay in catastrophic failure and (iii) total dissipated energy. We then investigated the role of the pitch angle on the activation of the highly dissipative sub-critical failure mechanisms responsible for the high mechanical performances achieved by small pitch angles laminates. Our investigation clearly shows that, with ultra-thin-ply CFRP, smaller pitch angles achieve higher damage tolerance and structural integrity.
  • Effects of accelerated weathering on the mechanical properties of hemp
           fibre/ polybenzoxazine based green composites
    • Abstract: Publication date: Available online 3 October 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Abdul Qadeer Dayo, Aijaz Ahmed Babar, Qi-rui Qin, Sadia Kiran, Jun Wang, Ahmer Hussain Shah, Abdeldjalil Zegaoui, Hamid Abdelhafid Ghouti, Wen-bin Liu In the current study, three different kinds of hemp fibre treated polybenzoxazine composites were exposed to accelerated weathering at 30 oC and 80% relative humidity (RH), till the saturated moisture uptake. The tensile, flexural, and impact properties of saturated samples were evaluated and results were compared with the unconditioned samples. The silane treated hemp fibre (STHF) composites showed the lowest decline in the properties. Afterwards, the STHF composites were exposed to various accelerated weathering conditions, in the range of 25-35 oC and 40-80% RH. Moisture uptake was slightly increased and tensile and flexural properties were gradually decreased as the exposure temperature and RH were increased. Highest decline was observed in the samples exposed at 35 oC and 80% RH. Furthermore, the slightly higher impact values were observed for the exposed composites. The composites colour was slightly lost and changes to lower shaded as the temperature and RH were raised.
  • Swarm intelligence integrated micromechanical model to investigate thermal
           conductivity of multi-walled carbon nanotube-embedded cyclic butylene
           terephthalate thermoplastic nanocomposites
    • Abstract: Publication date: Available online 24 September 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Seong Yun Kim, Ji-un Jang, Bezawit F. Haile, H.K. Lee, Beomjoo Yang With the recent demand for miniaturization and integration of electronic devices, there has been a growing interest in device malfunction due to high temperature. In this study, a experimental and theoretical study on the composites with improved thermal conductivity by dispersing multi-walled carbon nanotubes (MWCNTs) in the thermoplastic resin was carried out. A micromechanical model was derived based on the ensemble volume-averaging method and the modified Eshelby’s tensor reflecting the interface properties. The effects of the waviness, interface, and orientation of fillers on the thermal conductivity of composites were numerically analyzed. A computational intelligence-based particle swarm optimization (PSO) algorithm was adopted to the proposed model for optimizing the model constants. The thermal conductivity of the polymerized cyclic butylene terephthalate (pCBT)/MWCNT composites was experimentally measured according to the content of MWCNT. Finally, the experimentally measured data were utilized in the PSO to improve the predictive capability of the proposed model.
  • Mitigating forming defects by local modification of dry preforms
    • Abstract: Publication date: Available online 23 September 2019Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Mark A. Turk, Bruno Vermes, Adam J. Thompson, Jonathan P.-H. Belnoue, Stephen R. Hallett, Dmitry S. Ivanov Forming of dry fibre textile pre-forms is a commonly used technique to achieve complex shapes for light weight composite structures. Most conventional engineering fabrics can only deform through shearing. Excessive shearing often results in the formation of detrimental features, such as wrinkles, folds and fabric distortions. This paper shows the feasibility of improving formability by local modification of preforms in critical areas to enhance forming and mitigate against defects. Modification is implemented by printing localised resin patches onto textile preforms. The technique allows for continuity of fibres throughout the preform with the additional benefit that the deposited resin can be thermally staged to the desired level of cure to tune the viscosity of the region for forming and consolidation. The location and dimensions of patches are specified through numerical modelling to inform the subsequent manufacturing process. Manufacturing trials successfully demonstrate the possibility of defect mitigation using this technique.
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