bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Shot-Peening on the Fatigue Life of Unidirectional Titanium-Based Metal Matrix Composites
Authors: Solis-Romero J. , de los Rios E. R. , Rodopoulos C. A. , Yates J. R. , Godfrey S. P.
Published: January 2019

This pioneer work demonstrates the possible link between surface engineering techniques like shot-peening (SP) and metal matrix composites. The SP process on MMCs aims to reduce the amount of tensile residual stresses developed on the matrix during manufacturing and consequently to allow the matrix to bear significantly higher strains at the crack tip during cycling. Measurements taken from peened 32%, SM 1140/Ti-6-4[ 8 ] revealed notable changes in the profile of the matrix residual stresses. Further experimental work revealed an increase of 45% on the fatigue limit of the peened material.
Influence of the Detailed Structure of two Variants of Non-Crimped Carbon Fabric on the Drape Properties
Authors: Potter Kevin
Published: January 2019

Two carbon fibre non-crimped fabrics have been subjected to a drape evaluation using bias extension testing. The two fabrics were produced by different suppliers but were nominally identical in structure, in terms of fibre type and directions, weight/unit area, stitch style, pitch and density. Despite the close similarity between the two materials, their bias extension responses were dramatically different. This paper compares the bias extension behaviour of the two materials and discusses the small differences in structure that lead to great differences in performance.
Thermoelastic Behaviour of Synthetic Rubber/Organoclay Nanocomposites at Low Elongations
Authors: Privalko V.P. , Ponomarenko S.M. , Privalko E.G. , Schon F. , Gronski W.
Published: January 2019

Melt-compounded nanocomposites of synthetic styrene- co-butadiene rubber (BUNA SL18) and clay particles pretreated with three different modifiers were characterised by stretching calorimetry in the range of relative elongations λ < 1.3. In contrast to the pristine rubber, all nanocomposites exhibited irreversibility of both mechanical work and heat effects in stretching/contraction cycles at fairly low elongations. The observed irreversibility was considered as evidence for chain slippage effects.
Optical Fibre Flow-Sensor for Composites Manufacturing
Authors: Lekakou C. , Cook S. , Ang T.W. , Reed G.T.
Published: January 2019

An optical fibre has been used as an intensity-based sensor for the monitoring of the fluid front infiltrating a reinforcing fibre mat in composites manufacturing. The sensor length comprised the fibre core, initially surrounded by air or vacuum and subsequently covered by the infiltrating fluid. Two configurations were tested where a step-change or a continual output signal was obtained, respectively. In the latter case, the sensor used in this study demonstrates an improvement of up to two orders of magnitude over conventional monitoring techniques used for this application. This performance is coupled with more obvious advantages of low cost, compatibility with composite fabrication, and ease of use.
Percolation and Gas Sensing Behaviours of Ternary Conductive Composites: Vapour-Grown Carbon Fibres/Carbon Black/Poly(Methyl Methacrylate)
Authors: Dong Xian Ming , Qin Zhi Pei , Fu Ruo Wen , Zhang Ming Qiu , Zhang Bin , Rong Min Zhi
Published: January 2019

To reduce the dosage of carbon black (CB) in conductive polymer composites, vapour-grown carbon fibre (VGCF) were incorporated in the present work. The experimental results indicated that only small amount of VGCF is sufficient to significantly improve the conductivity of the composites based on poly(methyl methacrylate) (PMMA), as characterized by an additional percolation process. Besides, the ternary composites exhibit electrical responsivity to saturated ethyl acetate vapour as high as 105 in association with good reproducibility. In comparison to CB/PMMA composites having the same filler loading, VGCF/CB/PMMA composites provide higher response rate and recoverability.
Frequency Analysis and Process Monitoring in Drilling of Composite Materials
Authors: Kim D. , Ramulu M.
Published: January 2019

Drilling experiments were conducted using carbide and cryogenic treated carbide drills into carbon fiber-reinforced thermoplastic composites, namly Graphite/PIXA-M (PIXA-M) composites. Drilling force signals were collected from all conditions and analysed using fast Fourier transformations and autoregressive (AR) time series models. Power spectrums were used to examine the cutting characteristics in the drilling process. AR coefficients were used to distinguish the cutting signals of autoclaved and induction heated PIXA-M composites, and conventional and cryogenic treated carbide drills.
Generalized Shear-Lag Analysis Including Imperfect Interfaces
Authors: Nairn J. A.
Published: January 2019

Two recent papers showed that shear-lag analysis can be an effective tool for stress analysis of composites when done properly and when applied to problems for which it is appropriate. This paper extends the prior analysis of concentric cylinders to a generalized shear-lag analysis in which the transverse variations of shear stress are described by arbitrary shape functions. The shear-lag analysis and solution can be derived in terms of averages of the new shape functions. The shape functions can be specified after analysis and tailored to suit specific problems. This paper also extends shear-lag analysis of both concentric cylinders and multilayered structures to model imperfect interfaces between the layers. The generalized methods were applied to several issues in fibre/matrix stress transfer modelled as two concentric cylinders. By modifying prior shape functions, it was possible to extend shear-lag analysis to work for any fibre volume fraction. Prior shear-lag models were all unacceptable at low fibre volume fraction. The full shear-lag analysis can model stress transfer for both isotropic and anisotropic fibres. The new imperfect interface capability was used to interpret experimental results for fibre/matrix stress transfer in terms of interface quality.
Mechanical and Crash Behaviour of Sheet Moulding Compound Materials
Authors: Yuan Qiang , Bateman Stuart , Ye Lin
Published: January 2019

The mechanical and crush behaviour of high-performance sheet moulding compounds (SMCs) was studied. SMC laminates and half tubes were consolidated using a hot press. SMC tubes were made using two half tubes joined together with adhesive bonding and/or mechanical fastening. Both high-toughness SMC (SMC-T) and high-strength SMC (SMC-S) showed excellent tensile and flexural properties under static loading. The fracture toughness of SMC-S was somewhat higher than that of SMC-T, but at room temperature the energy absorption of SMC-T was higher than that of SMC-S. However, the impact strength of SMC-T decreased rapidly with increasing temperature, while that of SMC-S dropped only slightly up to 100°C. Dynamic mechanical thermal analysis (DMTA) results showed that SMC-S maintained its mechanical properties up to 150°C, while the storage modulus of SMC-T reduced rapidly with increasing temperature. SMC tubes were crushed at a speed of 500 mm/min. The specific energy absorption of both SMC-S and SMC-T tubes could reach 50 kJ/kg. The crush strength of the mechanically fastened SMC tubes was much higher than that of adhesively bonded ones.
Modelling Fatigue Life of Multidirectional GFRP Laminates under Constant Amplitude Loading with Artificial Neural Networks
Authors: Vassilopoulos Anastasios P. , Georgopoulos Efstratios F. , Dionysopoulos Vasileios
Published: January 2019

An artificial neural network has proven to be a sufficient tool for modelling fatigue life of multidirectional composite laminates made of Glass Fibre Reinforced Plastic (GFRP) composite materials and tested under constant amplitude loading patterns. Modelling efficiency of the network was satisfactory for both on- and off-axis coupons life, irrespective of test conditions, i.e., R-ratio that defines the developed stress state on the coupon. Tension-Tension, Compression-Compression and even Tension-Compression loading patterns were investigated and modelling accuracy of the proposed ANN model was validated. The main benefit that this new modelling tool brings is that only a small portion, in the order of 40%-50%, of the experimental data is needed for the whole analysis and thus, expensive and time consuming tests needed for the establishment of S-N curves could be eliminated without any significant loss of accuracy.
Mechanism of Increasing the Electromagnetic Absorption of Composites Prepared by BaFe12O19 and TiO2
Authors: Qiu Jianxun , Lan Lijuan , Zhang Hong
Published: January 2019

The composites of BaFe12O19 and TiO2 are prepared with sol-gel method. The imaginary parts of the relative complex permittivity and permeability, sublattice structure, and saturation magnetization of composites were measured with vector network analysis, Mϕssbauer spectroscopy, and vibrating sample magnetometry. The doping by TiO2 changes the sublattice structure of BaFe12O19, and results in the quadrupole splitting and isomer shifts. The capabilities of dielectric and magnetic losses of BaFe12O19 are improved. The effect of the doping by TiO2 on improving the energy absorption of BaFe12O19 is analyzed.
Microstructural Analysis of SiO2/Polyethylene Nanocomposites on Local and Macroscopic Scales
Authors: Lehmann B. , Sustacha J. , Schlarb A.K. , Friedrich K. , Zhang M.Q. , Rong M.Z.
Published: January 2019

High density polyethylene filled with nano-SiO2 of different face modification and content is investigated by nanoindentation, microindentation, scratching and dynamic mechanical thermal analysis. The results of the nanoindentation are compared with respect to more macroscopic measurements in order to obtain information if the surface modification and/or the filler content significantly changes the material properties on a local scale.
Measurements of Yarn Paths in 3D Braids
Authors: Tolosana N. , Koissin V. , Lomov S.V. , Stóve J. , Miravete A. , Gonzalez J.
Published: January 2019

Internal structure of 3D braids with square or rectangular cross-section is studied experimentally. The yarn paths and cross-sections are measured using the marked yarn technique. The presented data can be useful for validation of theoretical models of a 3D braid internal geometry.
Effect of Nanodiamond Particles on Properties of Epoxy Composites
Authors: Špitalský Zdeno , Kromka Alexander , Matějka Libor , Černoch Peter , Kovářová Jana , Kotek Jiří , Šlouf Miroslav
Published: January 2019

The epoxy nanocomposites filled with 0.1, 0.5, and 1 wt% nanodiamonds (nanoD) were prepared and their properties were compared with neat epoxy network or epoxy nanocomposite filled with 1 wt% multiwalled carbon nanotubes (MWCNTs). The obtained nanoD-epoxy composites increased significantly thermal stability of prepared nanocomposites in comparison with neat epoxy matrix. The exponential decay of light transmittance with increasing concentration of nanoD in sample was observed. The values of storage modulus G` and glass transition temperature Tg significantly decreased by addition of nanoD to epoxy network. This is caused by inhibition of cross-linking reaction of epoxy- and amino- groups by nanoD.
Multi-Wall Carbon Nanotubes Chemically Grafted and Physically Adsorpted on Reinforcing Carbon Fibres
Authors: Karapappas P. , Tsantzalis S. , Fiamegou E. , Vavouliotis A. , Dassios K. , Kostopoulos V.
Published: January 2019

Carbon nanotubes (CNTs) because of their properties are alleged to be the key candidate additives for improving the mechanical properties of polymers and carbon fibre reinforced polymers (CFRPs). Nevertheless in order for the reinforcing effect of the nanotubes to be of practical use, the CNTs have to be mixed with the matrix material. In the current work an effort was made to chemically graft Multi-Wall Carbon Nanotubes (MWCNTs) on the actual reinforcing Carbon Fibres (CFs) in order to skip the sometimes complex mixing stage. Two different solutions were used in order to treat/prepare the CNTs; a) an acid solution of H2SO4/HNO3 and, b) a toluene solution. The treated CFs were added to each solution, sonic bathed with deionised water and then dried in an oven. The resulting CFs were examined under SEM and both the solutions used proved to be reasonable successful with further investigation/optimisation to be necessary.
Preparation of Solution Impregnated Continuous Carbon Fibre Reinforced Poly (Phthalazinone Ether Sulfone Ketone) Composites
Authors: Zheng Liang , Liao Gong Xiong , Jian Xi Gao
Published: January 2019

Continuous carbon fibre reinforced Poly (phthalazinone ether sulfone ketone) (PPESK) composites were prepared using a solution impregnation process and hot-press molding method. The effects of polymer solution viscosities on fibre impregnation, fibre volume fraction and thereby on mechanical properties of composites were studied. The results show that the fibre impregnation and fibre volume fraction decreased with increasing polymer solution viscosities, and the mechanical properties of composites mainly depended on the fibre volume content.
Evaluation of the Tribological Properties of Poly(Vinylidene Fluoride) Composites Filled with Carbon Fibers
Authors: Li J. , Li X.Z.
Published: January 2019

The tribological performance of poly(vinylidene fluoride) (PVDF) and carbon fibre reinforced poly(vinylidene fluoride) (CF/PVDF) were examined. Different contents of carbon fibres were employed as reinforcement. All filled and unfilled polyimide composites were tested against CGr15 ball and representative testing was performed. The effects of carbon fibre content on tribological properties of the composites were investigated. The worn surface morphologies of neat PVDF and its composites were examined by scanning electron microscopy (SEM) and the wear mechanisms were discussed. Moreover, all filled PVDFs have superior tribological characteristics to unfilled PVDFs. The optimum wear reduction was obtained when the content of carbon fibre is 20vol%.
Effect of Particle Morphology on the Properties of Polypropylene/Nanometric Zinc Oxide (PP/Nanozno) Composites
Authors: Lin Ong Hui , Akil Hazizan Md , Mahmud Shahrom
Published: January 2019

Polypropylene/nanometric zinc oxide (PP/nanoZnO) composites at 1 wt% nanoZnO content were prepared using melt blending method using a thermo Haake internal mixer. Three different types of zinc oxide (ZnO) with different morphologies were used as fillers. Each composite was subjected to characterization analyses including tensile testing, UV-vis spectroscopy and electron microscopy. The tensile strength, tensile modulus and elongation at break of the PP/nanoZnO composites were observed to be greatly enhanced despite the low filler content (1 wt%). All ZnO-reinforced composites exhibited superior UV absorption characteristic especially for composite specimens reinforced with ZnO morphology rich in nanorods.
Numerical Investigation of the Dynamic Response of Symmetric Laminated Composite Beams to Harmonic Excitations
Authors: Kıral Zeki
Published: January 2019

The aim of this study is to investigate the dynamic response of a laminated composite beam subjected to a harmonic excitation by a numerical time integration method known as Newmark method. The finite element method based on the classical laminated plate theory is used in order to obtain structural stiffness. The structural damping is modelled as proportional damping which is referred to as Rayleigh damping and two different damping ratios are used. The effect of damping on the frequency response of the beam is investigated for a broad range of excitation frequency. The effect of excitation point on the harmonic response is also considered. Four different lay-up configurations namely [0]2s, [0/90]s, [45/-45]s and [90]2s are considered in order to show the effect of the stacking sequence on the frequency response of the beam. The numerical results presented in this study show that, the magnitude of the harmonic response of the beam reduces considerably as the damping ratio increases and [90]2s lay-up produces largest dynamic response due to the reducing flexural rigidity. Numerical results also show that the location and frequency of the harmonic excitation has important role on the dynamic response of the beam.
Moisture Absorption and Degradation of Glassfibre/Vinylester Laminates with Internal Flow Layers
Authors: Mannberg Peter , Holmberg J. Anders
Published: January 2019

Vacuum Infusion is a closed mould manufacturing process that can replace open mould processes. To improve resin flow it is common to add flow enhancement layers to the reinforcement stack. The basic feature for all flow enhancements is a coarse micro structure with regions of low fibre content. Degradation of mechanical properties due to environmental loading such as temperature and moisture is very important. A lot of research has been done on this area but earlier work has been done on materials without internal flow layer. The question is how well vacuum infused laminates, based on reinforcements containing internal flow layer, resist environmental ageing. Present work presents 3000 h 90°C water ageing data and differences between the material types in the rate of water uptake, Tg, mechanical properties and density was investigated. The results show that the relative weight gain is an increasing function of time. From the Tg measurements we see that Tg is increasing for the immersion aged materials. Tensile tests after 3000 h of immersion ageing show a decrease in Young's modulus, tensile strength and failure strain for the immersion aged material. Density measurements show that the average density has increased for the immersion aged materials.
Tensile Behaviour and Damage Evolution of a C/SiC Minicomposite Fabricated by Chemical Vapour Infiltration
Authors: Wang Yiqiang , Zhang Litong
Published: January 2019

The tensile behaviour of a C/SiC minicomposite fabricated by chemical vapour infiltration was examined and the associated damage evolution was monitored by using acoustic emission (AE) technique. The microstructure of minicomposite can be characterized by a uniformly thick SiC sheath, the thin fibre coatings, and large pores due to the tendency of fibres to cluster in the minicomposite. The load-displacement curves of minicomposite show a greatly nonlinear behaviour with four distinct regimes: initial self-alignment due to relaxation of fibres followed by preexisting microcrack extension, matrix macrocrack multiplication and then saturation. All these regimes can be well characterized by the corresponding AE activities. Therefore, it is believed that such experimental results would be beneficial to the optimization of processing conditions and derivation of parameters necessary for further modelling of the thermomechanical behaviours of real C/SiC composites with more complex architectures by fabricating minicomposites in a short time.
Ceramifying Fire-Resistant Polyethylene Composites
Authors: Shao Haibin , Wang Tingwei , Zhang Qitu
Published: January 2019

Glass fillers were added into polyethylene (PE) with the aim to prepare fire-resistant PE composites. The effect of glass additives on ceramification of the composites and the properties of ceramic residue was investigated. Scanning electron microscopy (SEM) showed that there was a stronger interaction between glass fibres than that between glass powders. A torque rheometer was used to explore the rheological behaviour. It was concluded that expansion of composites was driven by the motion of low molecular weight substances such as water, carbon dioxide pyrolysed during heat treatment, while softened inorganic additives shrank at elevated temperature resulted in shrinkage of composites. The effect of the form and softening point of glass additives on waterproofness and thermal shock resistance of residue was investigated. The results showed that the composition significantly affected the compactness of residue. Thermal shock resistance of residues of each composite was good. Combustion tests showed that flame retardance and anti-dripping of the composites should be improved.
Buckling Optimization of Wood Composite Columns with Variable Cross-Sectional Area: A Comparison between two Tree Species
Authors: Pekbey Yeliz , Ozdamar Aydogan , Sayman Onur
Published: January 2019

The minimization of structural weight and the maximization of critical buckling load are problems that have been addressed many times. The problem of maximizing the buckling load of a wood composite column of given volume, length and material is studied. Tadjbakhsh and Keller were the first to obtain an optimum solution analytically for the case of clamped-clamped case. Unimodal solutions obtained by Tadjbaksh-Keller are not optimal because they buckle by the modes with discontinuities of the slope corresponding to the lower critical load. This leads to taking into account bimodal formulation of the optimization problem. Olhoff-Rasmussen (1977) first discovered that the unimodal solution given for the clamped by Tadjbaksh-Keller (1962) is incorrect. The optimal columns must be considered from the point of view of practical design. In this paper, it will be shown that bimodal solution is not practical and optimal since in points of minimum thickness crush occurred but not buckling. This leads to the necessity of both stability and crush formulation of the optimization problem. The present contribution of this paper is that crush is taken into account in the formulation of column optimization problem allowing for bimodal optimum solution. To test the accuracy of our new optimization column with clamped ends, experimental data were compared to numerical analysis using ANSYS. Both necessary and sufficient optimality conditions are derived. One important conclusion of this paper is that our new optimal solution is in agreement with results obtained by numerical analysis and by experiments.
Biological Response of Biphasic Hydroxyapatite/Tricalcium Phosphate Scaffolds Intended for Low Load-Bearing Orthopaedic Applications
Authors: Baghbani F. , Moztarzadeh F. , Nazari A. Gafari , Kamran A.H. Razavi , Tondnevis F. , Nezafati N. , Gholipourmalekabadi M. , Mozafari M.
Published: January 2019

In this study, a calcium phosphate scaffold of hydroxyapatite (HAp) and dicalcium phosphate dihydrate (DCPD) for application in osteoconductive and osteoinductive scaffolds was synthesized and characterized. The important note is that the prepared composites converted to HAp/tricalcium phosphate (TCP) after heat-treatment. This class of composites is interesting because porous HAp/TCP generally degrade more rapid than HAp due to the increased resorption rate of TCP. According to the obtained results, the values of elastic modulus, compressive strength and density of the samples reduced with increasing the percentage of the DCPD phase. It is worth mentioning that the mechanical properties of the prepared samples were near the natural compact bone. The samples were examined in vitro to confirm the apatite forming ability of the composites. Also, in vivo examination in a rabbit model was employed. After fully observation it was concluded that new bone formed on the pore walls, as osteoids and osteoclasts were evident two months postoperatively. Based on the obtained results, the prepared scaffolds seem to be a promising biomaterial for low weight bearing orthopaedic applications.
Polyethylenimine-Silica Mesoporous Hybrid: A Novel Adsorbent for CO2 Capture
Authors: Fu Xin
Published: January 2019

A facile pathway has been developed to synthesize polyethylenimine-modified mesoporous hybrid materials with highly efficient CO2 capturer. It is the special feature of this pathway that there are no surfactants introduced and the amine guest can be dispersed within the channels of the silica materials during the hydrolysis and polycondensation process. The obtained materials exhibit high specific surface areas, high porosity and high CO2 uptake. The amount of polyethylenimine (PEI) has important effect on the surface area, pore size and CO2 adsorption capacity of the adsorbents. For the sample containing 50 wt% PEI, the adsorbent exhibits a high adsorption capacity of 186.6 mg/g-PEI, and in situ FTIR show that CO2 is sorbed on amine sites through the formation of alkylammonium carbamates. The adsorbed CO2 could be desorbed completely from the sample at 150 °C. Moreover, the adsorbents show a stable cyclic adsorption-desorption performance.
Fabrication and Mechanical Properties of Cnt/6063 Al Composites Prepared by Vacuum Assisted Infiltration Technique Using Cnt-Al Preforms
Authors: Kucukyildirim Bedri Onur , Eker Aysegul Akdogan
Published: January 2019

Industrial type multi-walled carbon nanotube (MWCNT) reinforced aluminum (Al) matrix composites are successfully fabricated by vacuum assisted infiltration of Al into the CNTs-Al preform and compressive mechanical properties of these composites are investigated. The compressive properties and hardness of CNT reinforced composites are fairly increased compared with the previous CNT/Al composite studies. Furthermore, our study confirms that the mechanical enhancements of the composites are interrelated with bridging and pulling-out of CNTs in the fracture surfaces. Moreover, the presence of CNTs leads to dispersion strengthening of the matrix because of their nano size.
Microstructures and Wear Resistance of Laser Melting Deposited Composites on Ati-Alloy
Authors: Peng Li
Published: January 2019

This work is based on the dry sliding wear of Stellite 4-FeSi-B4C composites deposited on a TA10 titanium alloy using a Laser melting deposition (LMD) technique, the parameters of which are such as to provide almost crack-free composites with very low porosity. To our knowledge, it is the first time that Stellite4-FeSi-B4C mixed powders are deposited as the hard composites by the LMD technique. Scanning electron microscope results indicate the nanoscale particles and nanorods are produced in such composites. Furthermore, due to the characteristics of the laser technology, the ultrafine nanoscale polycrystalline phases can be easily produced. Compared with a TA10 alloy substrate, the improvements of the micro-hardness and wear resistance are obtained for such composites.
Novel Route for Incorporation of Palladium Nanoparticles into Mesostructured Silicas Sba 15 and Sba-16
Authors: Ivashchenko N. , Tertykh V. , Skubiszewska-Zięba J. , Leboda R. , Khainakov S. , Oranska O.
Published: January 2019

Palladium nanoparticles with controlled size were synthesized within the pores of the mesoporous SBA-15 and SBA-16 silicas with grafted silicon hydride groups. Nitrogen adsorption-desorption method, X-ray diffraction and transmission electron microscopy (TEM) were used for characterization of palladium-containing composites. Results of material study clearly revealed that Pd nanoparticles prepared by this method were located inside the porous channels and were quite uniform in size (mostly 5–6 nm). The influence of metal content on the particles size and porous structure of supports was investigated.
A Study on Continuous Flax Fibre Reinforced Polypropylene Composite in Stamp Forming Process
Authors: Wang Wentian , Lowe Adrian , Kalyanasundaram Shankar
Published: January 2019

This study investigates the forming behaviour of flax fibre reinforced polypropylene composites through stamp forming. A real time photogrammetric three dimensional strain measuring system was employed to capture the surface motion and compute strain deformation during forming. Failure mechanisms exhibited in the flax/polypropylene composites at different forming temperatures were determined by visual and microscopical examinations. Fibre fracture was identified as the major failure mode. At a forming temperature of 160 °C, fibre pull out was also observed in addition to fibre fracture. A study of forming modes exhibited at various forming temperatures illustrated that there is an optimal temperature window for forming. A key finding from this work is that the matrix shear deformation can aid in superior forming for this class of material systems.
Effect of Preheating and Post-Curing Time on the Mechanical Properties of Epoxy Resin
Authors: Bourchak Mostefa , Khan Adnan , Juhany Khalid A.
Published: January 2019

The purpose of this study is to compare the mechanical properties in the form of ultimate tensile strength, ultimate tensile strain and Young's modulus of an epoxy resin at different curing cycles. The work carried out consisted of investigating the effect of preheating time and then the effect of post-curing time at the same temperature. Five repeats of static tensile tests were then carried out using universal test machine. Results indicated that compared to a shorter epoxy resin preheat duration of 15 min at 80°C, a longer duration of 30 min at 80°C of preheating degrades the material ultimate tensile strength and ultimate tensile strain leading to a suffer material. However, compared to no further post-curing of the epoxy resin, a two-hour post-cure duration at 80°C slightly increased the ultimate tensile strength and significantly decreased the ultimate tensile strain making the material even suffer than in the case of preheating. The implication is that in-house cure cycle tests should be carried out to characterize the resin instead of exclusively relying on resin manufacturer proposed cure cycles.
Investigation of Fluorine Incorporation within Gelatin/Calcium Phosphate Nanocomposite Scaffold Prepared through a Diffusion Method
Authors: Baheiraei Nafiseh , Azami Mahmoud
Published: January 2019

In this study diffusional method was used to prepare a biomimetic calcium phosphate/gelatin nanocomposite as a scaffold for bone and tooth tissue engineering. Incorporation of fluorine into mineral phase of the scaffold was also investigated. Addition of fluoride to the synthesis process caused formation of fluoroapatite and calcium fluoride along with hydroxyapatite within gelatin while in the sample lacking fluorine atoms, hydroxyapatite and octacalcium phosphate were detected. With addition of fluorine within the structure of precipitated minerals, morphology of minerals was dramatically changed from oriented rod-like minerals with rectangular cross section toward spherical particles consisting of smaller crystals with uneven surface scattered over the gelatinous bulk material.
Energy Absorbed by Composite Conical Structures in Axial Crushing
Authors: Boria Simonetta , Pettinari Silvia
Published: January 2019

Recently crashworthiness trend is the use of thin-walled composite impact attenuators in specific vehicle zones, ensuring kinetic energy absorption. The present paper addresses the composite conical structures design using an analytical approach for predicting energy dissipation in a controlled way. A balance of internal energies involved in the absorption and external force yields the average crush load and the total displacement through a numerical method. Comparison between theory and experiments shows the efficiency of the proposed relatively simple model for predicting energy absorption of axially collapsing composite shells.
Non Destructive Analysis of Carbon Nanotube Based Strain Sensor Using Raman Analysis and Raman Mapping
Authors: Deepak A. , Ramya S. , Ganesan Vaidehi , Shankar P.
Published: January 2019

The objective of this work is to use techniques like Raman analysis, XRD and AFM imaging to confirm that multiwall carbon nanotubes (MWCNT) based Polyvinylidene Fluoride (PVDF) composites can be used in strain sensing engineering applications. ID/IG ratio, obtained from Raman Analysis is used to predict the defect level and study the details related to uniformity and smoothness of an unstrained film with respect to a strained film. By comparing the band shift in the spectra, the defect level present in a strained specimen compared to that of an unstrained specimen can be predicted. Area mapping is also carried out to check the homogeneity of the film. AFM analysis is also carried out to correlate the relationship between surface roughness and defects of the film with ID/IG ratio obtained from Raman Spectrum.
Optimization of Wedm Parameters for Surface Roughness on Hybrid Mmcs
Authors: Satishkumar D. , Kanthababu M.
Published: January 2019

Metals or alloys when reinforced with more than one reinforcement materials are generally considered as hybrid metal matrix composites (MMCs). The superior properties of the hybrid MMCs deter its wide applications due to the difficulty in machining. Wire electrical discharge machining (WEDM) is an effective unconventional machining process which can be used to machine difficult to machine materials. This work is aimed towards optimizing the WEDM parameters to achieve better surface roughness ( Ra) during machining of stir cast unreinforced A17075 alloy and A17075/B4C/Al2O3 based hybrid MMCS. The experiments were carried out as per central composite design of response surface methodology (RSM). It is observed that all the process parameters such as pulse-on time ( TON), pulse-off time ( TOFF), wire feed (F), gap voltage (V) considered in this work were significant.
Experimental Study of Sandwich Multilayer Reinforced by Glass Fibre and Agglomerated Cork
Authors: Hami B. , Irekti A. , Aribi C. , Bezzazi B. , Mir A.
Published: January 2019

This paper presents an experimental study which is determined the mechanical properties of a composite material sandwich multilayer developed in the laboratory of mechanics of materials and composites, Materials Research Unit, process and environment. This type of sandwich is composed of four layers laminated based on an epoxy resin reinforced by woven glass fibres and mast between which three plates of agglomerated cork with stacked alternately laminated layers. Specimens for bending tests three and four points were prepared from the multilayer sandwich panels. A first series of static three-point bending tests shows a clear difference in the fracture behaviour for materials, laminate and cork. These materials have undergone a large plastic deformation without rupture achieve full sandwich, with the onset of delamination between layers laminated material and cork. In order to determine the bending stiffness modules D, the shear modulus and flexural N and the shear modulus of the soul Ga, we conducted a second test campaign four points bending. As a result, we can develop a variety of white cork produced in Algeria in order to use it in the construction and automotive industries.
Influence of Mesophase Pitch on Thermal Conductivity OF CNTs-Based Nanocomposite
Authors: Zhang Zhe Juan , Zhu Qing , Mao Yanting , Sun Zhuo
Published: January 2019

Mesophase pitch solution was melted into carbon nanotubes (CNTs) sheet to fabricate carbon composites. The influence of heat treatment and mesophase pitch on microstructure and thermal conductivity was investigated. The structure evolution was characterized by SEM, Raman spectroscopy and thermal behavior was studied by thermal Analyzer. The results reveal that CNTs in nanocomposites linked each other by pitch carbon and form into CNTs networks. The micro structure and crystallization of CNTs-based nanocomposites appear to be improved by changing carbonization temperature from 400 to 800. The results proved that the thermal conductivities of CNTs-based nanocomposites are directly affected by carbonization temperature after pitch compounded with CNTs sheet.
Buckling Load Design of Long Cross-Ply Laminates of Hybrid Construction with Material Uncertainties
Authors: Radebe Isaac Sfiso , Adali Sarp
Published: January 2019

Elastic constants of composites are often determined with some level of uncertainty. In the present study minimum cost design problem for long cross-ply plates of hybrid construction is solved subject to material uncertainties. By using minimum amount of more expensive composite in outer layers and less expensive composite in inner layers, a more efficient and cost-effective design is obtained. The effect of hybridization is studied for uniformly and linearly varying buckling loads.
Evolution of Static and Dynamic Properties of Gfrp Laminates during Ageing in Deionized and Seawater
Authors: Katunin Andrzej , Gnatowski Adam , Kajzer Wojciech
Published: January 2019

GFRP laminates are widely used for constructional purposes of boats and wind turbines. During the operation of elements made of these materials in environmental conditions they are subjected to contact with aggressive media like seawater. In this paper the authors evaluated the degradation process of GFRP laminates at the different stages of ageing in deionized and seawater based on evolution of static and dynamic properties. The analysis of evolution of tensile properties as well as dynamic moduli and characteristic temperatures of transition allow for concluding about the nature of the degradation mechanisms during ageing in various media. Obtained results allow describing this process, which can be applied at the stage of design as well as operation of GFRP elements contacted with water.
A Numerical Procedure for the Virtual Compression after Impact Analysis
Authors: Borrelli Rosario , Franchitti Stefania , Di Caprio Francesco , Romano Fulvio , Mercurio Umberto
Published: January 2019

The aim of the proposed research activity is to investigate on the structural behaviour of composite plates in order to develop numerical models able to describe their damage resistance to impact loads and their damage tolerance through compression after impact (CAI) test. The present paper presents a two-step simulation approach for determining the residual strength after a low velocity impact on a composite laminate of aeronautical interest. The first step is aimed at determining the damage extent after the impact event and it is performed by using an explicit finite element code. Hence, the damage status induced by the impact is transferred to the finite element model for the virtual compression after impact test which is simulated in a second step by using an implicit finite element code. Numerical results, in terms of force vs. displacement impact curve, damage envelope and reaction vs. applied strain compression curve, were compared to the experimental ones for validation purpose.
Artificial Neural Network Prediction of Ultimate Tensile Strength of Randomly Oriented Short Glass Fibre-Epoxy Composite Specimen using Acoustic Emission Parameters
Authors: Ramkumar S.
Published: January 2019

Acoustic emission (AE) data have been collected from 20 randomly oriented short E-glass fibre – unsaturated polyester tensile specimens, while loading up to failure in a tensile testing machine. Peak amplitude and cumulative energy data from AE response of each specimen were classified and segregated by understanding the failure mechanism and data acquired up to 50% of the failure load was utilized for analysis. An optimized feed-forward back-propagation (FFBP) type artificial neural network (ANN) was designed and the segregated data of amplitude hits and cumulative energy was processed using it. Even though the accuracy of both networks were satisfactory, amplitude hit based network gave better predictions of the ultimate tensile strength (UTS) than the energy based network. Also the performance of various training algorithms in the designed network was analysed and the results were compared.
Parametric Study of Dry Sliding Wear Behaviour of Functionally Graded Al LM25/Si3N4 Composite by Response Surface Methodology
Authors: Radhika N. , Raghu R.
Published: January 2019

Functionally graded aluminium LM25/silicon nitride composite was produced through stir casting followed by centrifugal casting and obtained a hollow cylindrical cast component with dimensions of 150 × 150 × 20 mm. The microstructural examination and the hardness test were carried out on the outer (1 mm) and inner surface (17 mm) as the function of radial distance from the outer periphery. The outer surface was observed with particle enriched region compared to inner surface and exhibited higher hardness. Hence the outer surface of the functionally graded composite was only further subjected to sliding wear test in pin-on-disc tribometer. The Central Composite Design in Response Surface Methodology was used to design the experiments for the selected parameters such as load (15–45 N), velocity (0.5–2.5 m/s) and sliding distance (500–2000 m). Regression test and Analysis of Variance were conducted to check the adequacy of the constructed model. The surface plots for wear rate showed that wear rate increased with increase in load and non-linearly varied with increase in velocity and sliding distance. Scanning Electron Microscopy analysis was conducted on the worn-out surfaces and observed mild to severe wear transition on increase of load.
Health Monitoring of Single Lap Joint of Woven Glass Fibre Reinforced Epoxy Composites Modified with MWCNTs
Authors: Turan Fatih , Aktaş Alaattin , Gürkan Koray , Güçlü Mehmet , Taşkin Yener , Demirci Tülay Bal
Published: January 2019

In this study, in situ monitoring of single lap joint of woven glass fabric reinforced epoxy composites modified with multi-walled carbon nanotubes (MWCNTs) is presented. Woven glass fibre reinforced/epoxy composite plates modified with 3% wt. highly electrically conductive MWCNTs were manufactured by hand lay-up process for obtaining adherends. MWCNTs were used in 1% and 2% by weight in order to investigate the effect of the MWCNTs level on the shear lap joint strength and the self-sensing sensitivity of bonded area. One, four, and seven plies of adhesive woven cloths were employed for bonding adherends to examine the thickness effect on both the shear lap joint strength and the self-sensing sensitivity of bonded area. In order to provide low electrical contact resistance, woven carbon fibres were placed on the top and bottom of the glass fibre layer during production. Results indicate that the health monitoring of lap joints in the woven glass reinforced epoxy composites can be successfully achieved.
Free Vibration Analysis of Laminated Composites by a Nine Node Isoparametric Plate Bending Element
Authors: Kalita Kanak , Ramachandran M. , Raichurkar Pramod , Mokal Sneha D. , Haldar Salil
Published: January 2019

Composite laminates are being widely used in engineering industry primarily due to their high strength-to-weight ratio. Considerable research has been carried out to understand the static and dynamic behaviour of laminated composite plates. There is much demand for developing efficient finite element codes which can predict the dynamic responses of laminated structures at affordable computational cost. In this paper a nine node isoparametric plate bending element has been used for free vibration analysis of laminated composite plate. The first-order shear deformation theory (FSDT) has been incorporated in the element formulation. Composite plates with different side-to-thickness ratio (a/h), ply orientations and number of layers have been analysed. Based on comparison with literature data, we propose that the present formulation is capable of yielding highly accurate results. Laminated composites with central cut-outs are also studied. Novel data is reported for skew laminated composites. It is found that the natural frequency increases with the increase in skew angle (a) and decreases with increase in aspect ratio (b/a) and thickness (h).
Electromagnetic Wave Absorbing and Mechanical Properties of Cement-Based Composite Panel with Different Nanomaterials
Authors: Yafei Sun , Peiwei Gao , Hailong Peng , Hongwei Liu , Xiaolin Lu , Kai Song
Published: January 2019

This paper presents the microstructures and mechanical and absorbing properties of double and triple layer, cement-based, composite panels. The results obtained show that the frequency range in 2-18GHz had less than −10dB effective bandwidth, which correlates with 3.7and 10.8GHz in double and triple layer cement-based composite panels. Furthermore, the double layer panel's compressive strength at 7 and 28 days was 40.2 and 61.2MPa, respectively. For the triple layer panel, the strength values were 35.6MPa and 49.2MPa. The triple layer panel's electromagnetic wave (EMW) absorbing properties were superior compared to the properties of the double layer panel. However, the triple layer panel's mechanical performance was inferior to that of the double layer panel. This study proposes that carbon nanotubes can effectively improve the compressive strength and interface structure of cement-based composite panels.
Fabrication and Properties of Magnesium Matrix Composite Reinforced by Carbon Nanotubes-Alumina Hybrid Reinforcements
Authors: Li Y J , Sun X W , Fan J W , Li B E , Cao H C , Liu W , Li H P
Published: January 2019

Magnesium matrix composite reinforced by carbon nanotubes (CNTs)-Al2O3 hybrid reinforcements was successfully fabricated by a novel process. CNTs-Al2O3 in-situ mixture was synthesized by directly growing CNTs on Al2O3 particles acting as the carrier of Ni catalysts via chemical vapour deposition. The influences of Ni catalyst content on the morphology, structure and yield of CNTs were investigated. By powder metallurgy process, the CNTs-Al2O3 in-situ mixture was dispersed in Mg powder to fabricate the CNTs-Al2O3 synergistically reinforced Mg matrix composite. The performance test results showed that, the Mg matrix composite possessed improved mechanical properties, and the strengthening effects of CNTs-Al2O3 in-situ mixture were prior to those of single CNTs or Al2O3 reinforcement. The improvement of mechanical properties was due to that the introduction of Al2O3 can promote the dispersion of CNTs in Mg matrix and improve the interfacial bonding between CNTs and Mg.
Study of New Type Clamp Made of Epoxy Vinyl Resin on Standing Pipe under Sea
Authors: Zhang B. , Wang Z. , Wang T. , Wang D.H.
Published: January 2019

The disadvantages of the traditional steel clamp include installation difficulty, a short service life. Therefore, a non-metallic clamp was designed to relieve these issues. MFE711 bisphenol-A epoxy vinyl resin was identified as the matrix materials needed to meet the requirements of corrosion resistance, impact resistance and other performances. After analyzing the wave load on the clamp, the resultant force on the cable protection pipe is 78784N, and its maximum equivalent stress is 73.78 MPa. This is less than the value of 155 MPa of yield strength on the clamp; therefore it meets the predetermined design requirements. Presently, there are 11 Clamp products that have been installed on the standing pipe under the offshore platform and will apply widely to engineering.
Fracture Analysis of a Square-Hole Mullite Ceramic Regenerator
Authors: Liu Yongqi , Shang Qinghui , Wang Yangxia , Zhang Donghuang , Sun Tiantian
Published: January 2019

According to actual working conditions, the heat transformation process of a square-hole honeycomb regenerator was analyzed using a thermo-solid coupling method. The distribution of the temperature field was analyzed first and then, based on the Mohr strength theory, the fracture position of the regenerator was analyzed. It was found that the temperature of the regenerator increased in a wave pattern with increased cycle time. The maximum temperature difference in its steady state was about 240. The variation of the temperature gradient on different parts of the regenerator revealed the same trend with cycle times. The temperature gradient of each node reached the highest at the end of the endothermic period and the beginning of the exothermic period. It was theorized that the position on the center hole with a high temperature gradient would be destroyed first. The stress state in the highest stress point was revealed to be bi-directional compression.