bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Properties of SiC Short-Fibre-Reinforced SiC Composites Fabricated by Tape Casting and Hot-Pressing
Authors: Lee Jae-Seol , Yano Toyohiko
Published: January 2019

In order to examine the effects of sintering additives on microstructure and mechanical properties of SiC short-fibre-reinforced SiC composites, a ZrO2-Y2O3-Al2O3 additive system was applied in this study. The aim of this study was to investigate the influence of the sintering additives on the mechanical properties of SiC/SiC composites using Tyranno SA short fibres. A ZrO2-Y2O3-Al2O3 mixture was chosen for fabrication of the short-fibre-reinforced SiC composites as sintering additives because of their relatively low densification temperature and non-reactivity with SiC. Compare with the previous results, the influence of sintering additives on the mechanical and thermal properties of the SiC/SiC composites was discussed.
An Energy-Based FEM Technique for Analysing Delamination Development in Fibre-Reinforced Polymers (FRP)
Authors: Fan Chengye , Jar P.-Y. Ben , Cheng J.J. Roger
Published: January 2019

This paper presents a technique that uses finite element method (FEM) to analyse energy release rate ( G) for delamination growth in fibre-reinforced polymers (FRP). Using end-notched-flexure specimen as an example, G values obtained from the technique show excellent agreement with those from compliance derivative or virtual crack closure techniques that have been widely accepted for this purpose. The new technique has the advantage on its simplicity for the G calculation and provides potentials for the prediction of a complex delamination growth pattern that often exists in large FRP structures when subjected to complex loading.
Synthesis and Characterization of LiZn Ferrite-Coated CNT via a Sol-Gel Method
Authors: Chang Sun , Kangning Sun
Published: January 2019

A novel CNTs-based composite, LiZn ferrite (Li0.435Zn0.195Fe2.37 O4) coated CNTs core-shell nanostructure, was successfully prepared by a sol-gel method. The core-shell hetero-nanostructure have confirmed by TEM and XRD. The effect of surface oxidation treatment of MWNTs was investigated by FT-IR. The result showed that MWNTs functionalized with–COOH and –OH, etc. groups form an efficient matrix for the growth of LiZn ferrite crystals.
Delaminated Polymer/Lamellar Aluminophosphate Nanocomposites Prepared via in SITU Polymerization
Authors: Wang Jingyu , Chen Guoping , Zhou Quan
Published: January 2019

A method to synthesize completely delaminated polymer/lamellar aluminophosphate (Mu-4) nanocomposites has been successfully developed, wherein organo-modification of Mu-4 followed by in situ polymerization was applied. It can be found that the long chain n-dodecylamine molecules can favor the intercalation of Mu-4 and thus readily make the Mu-4 layers delaminated in the polymer matrix compared with the short chain N,N-dimethylpropane-1,3-diamine.
Experimental Characterization of An E-Glass/Epoxy Composite Plate in Pin-Loaded Joints
Authors: Pekbey Yeliz
Published: January 2019

Because of increased use of composites, understanding the failure behaviour of composites is important for effective structural designs. In this study, an experimental investigation was carried out to study the behaviour of pin connected E-GLASS/EPOXY composite joints under static loading conditions. Several specimens were fabricated by varying width and hole-to-edge distance and tested in pin bearing. Details of the test-setup were given and the joint configurations were used in a series of 75 such tests on single bolt joints. The results of this study were presented as experimental characterization. The effects of geometric parameters such as ratio between end distance-hole diameter (E/D) and width ratio (W/D) were evaluated. Three failure modes were observed, net-tension, bearing and shear-out failure at the bolt, depending on the geometry adopted. Under single bolt-bearing conditions, the load-displacement curve labelled for E-GLASS/EPOXY composite with [0/90/45/-45/-45/45/90/0] stacking sequence. In addition, bearing strength, shearing and net-tension stress at failure data were presented as functions of the geometric ratios. The results provided useful information for the structural design with this material against joint failures. From the experimental results obtained, it was concluded that the edge distance ratio (E/D) of the specimen strongly affected the bearing strength of composites. In addition, width ratio (W/D) remarkably affected the failure mode. Bearing failure occurred if (E/D) and (W/D) were large enough. Bearing failure mode was thought as the desirable mode since it generally gave a higher strength and failure was less brittle. Net-tension and shear-out failure modes were catastrophic and not progressive. Therefore, the geometry of the composite plate in pin-loaded joints was designed to undergo bearing failure only.
The Vibration Response of Composite Sandwich Beam with Delamination
Authors: Baba Buket Okutan , Gibson Ronald F.
Published: January 2019

The aim of this study is to report the effect of delamination on the vibration characteristics of composite sandwich beams. The natural frequencies and corresponding vibration modes of a free-free sandwich beam with delamination of various sizes and locations are predicted using a two-dimensional finite element analysis (FEA). The presence of delamination affects the stiffness of the delaminated beam and results in differences on the natural frequencies of the beam. Assessment of the differences light the way for the existence, size and location of the delaminated region and can be used for a non-destructive evaluation of the damage characteristics of the delaminated beams. Vibration tests are conducted on fully bonded sandwich beams with carbon/epoxy laminated composite faces and foam core to verify the finite element results. Agreement between predictions of the model and experimental observations is good.
Failure Strength of E-Glass/Epoxy Composite Pinned Joints: Effect of Geometry, Clamping Torque and Laminate Orientation
Authors: Pekbey Yeliz
Published: January 2019

The experimental investigations described in this paper were conducted in order to study the strength and failure behavior of composite plate with pin-loaded conditions. The main objective of the present paper was to investigate the influence of certain factors on the strength of the pin-loaded in E-GLASS/EPOXY composite plate with different orientations such as [0/90/±30]s and [0/90/±60]s. These factors included the preload moment (M=0, 2 Nm), the ratio of the edge distance to the pin diameter ( E/ D), and the ratio of the specimen width to the pin diameter ( W/ D). The mechanical properties and failure strengths of E-GLASS/EPOXY composite were obtained with experimental measurements. Based on experiments, the effects of laminate orientation, and preload moment on joint strengths were systematically investigated. In addition, geometrical configurations of specimens were suitably varied in order to observe all possible failure modes. A total of 150 different pin-loaded composite plate specimens were tested under static loading conditions. The specimen tested exhibited different failure modes, consisting of bearing, net-tension and shear-out, depending on the geometry adopted. Guidelines for effective laminate orientations, geometrical configurations and preload moment for mechanically pin connected E-GLASS/EPOXY composite plate were specified based on ultimate bearing strength. From the experiments, it was also found that glass-epoxy with [0/90/±30]s yielded the highest bearing strengths. Bearing strengths reached when E/D and W/D ratios were equal or greater than 4 both [0/90/±30]s and [0/90/±60]s orientations. Besides, the experimental results showed that the load-displacement curve of specimen with M=0, had the lowest the failure strength. M=2Nm preload moment, had the maximum failure load.
Tribological Behaviours of Epoxy Composites Filled with Silicon Carbide Nanoparticles
Authors: Zhang Chun Yuan , Rong Min Zhi , Zhang Ming Qiu
Published: January 2019

Epoxy composites filled with silicon carbide nanoparticles were fabricated in this work. Sliding wear tests in association with morphological observation indicated that the wear mode of the nanocomposites was rather mild, forming a striking contrast to the severe wear of unfilled epoxy characterized by substantial material loss under the same measurement conditions. Both specific wear rate and friction coefficient of the nanocomposites were significantly lower than those of the unfilled epoxy. On the basis of mechanical testing and tribochemical analysis, it was found that the addition of nano-SiC particles into epoxy increased the mechanical properties of the matrix and facilitated some favourable tribochemical reactions during rubbing, which accounted for the great improvement in the tribological performance.
A Novel Self-Healing Epoxy System with Microencapsulated Epoxy and Imidazole Curing Agent
Authors: Rong Min Zhi , Zhang Ming Qiu , Zhang Wei
Published: January 2019

This work reported a novel epoxy system that can perform a self-repairing operation against cracks at elevated temperature. For this purpose, a two-component healing agent consisting of microencapsulated epoxy and imidazole was pre-embedded into epoxy matrix. The microencapsulated epoxy was self-synthesized in advance using poly(urea-formaldehyde) as the wall material through a two-step polymerization approach in an oil-in-water emulsion. The performance of the self-healing epoxy composite was evaluated by fracture toughness measurement. It was found that the self-healing epoxy containing 20wt.% healing agent received a healing efficiency of 106% at the optimum capsulated imidazole-to-epoxy weight ratio of 0.2.
Oxidized Multi-Walled Carbon Nanotube Film Fabrication and Characterization
Authors: Kastanis D. , Tasis D. , Papagelis K. , Parthenios J. , Tsakiroglou C. , Galiotis C.
Published: January 2019

The topological and mechanical properties of carbon nanotube films prepared by different oxidized treatments have been studied. Tensile parameters have been found to be strongly correlated with topological parameters such as porosity and bundle size. It was found that low porosity films prepared from highly oxidized CNTs result in the enhancement of their mechanical properties.
Use of Near-Infrared Spectroscopy for On-Line Monitoring the Quality of Prepreg Cloth
Authors: Li Wei , Huang Yu Dong , Chen Ping
Published: January 2019

On-line monitoring the prepreg quality in the polymer composite industry continues to be a major emphasis, it will reduce the amount of prepreg manufactured under “outside specifications”. A near-infrared spectroscopy has been implemented for measurement of resin content, pre-curing degree of resin and volatile content during the manufacture of glass/phenolic resin prepreg cloth. The regression method employed was partial least squares (PLS). The optimum models were obtained by selecting different spectral pretreatments and spectral ranges. The determination coefficients (R2) for the resin content, pre-curing degree and volatile content were 98.36, 98.76 and 98.33, respectively. The root mean squares of cross-validation (RMSECV) were 0.364, 0.145 and 0.182 respectively for the resin content, pre-curing degree and volatile content, respectively. The NIR method was applied to monitor the quality of prepreg cloth on line. The results showed that the monitored values were closed to the actual values. The study indicates that the on-line quality analysis of prepreg cloth was realised by using NIR technique.
Influence of Processing Conditions on the Micro-Mechanical Properties of Particulate-Reinforced Aluminium Matrix Composites
Authors: Myriounis D. P. , Hasan S. T. , Matikas T. E.
Published: January 2019

During processing, metal matrix attempts to deform and this deformation plays the key role in the microstructural events of segregation and precipitation at the matrix-reinforcement interface. The important aspect of this behaviour is to identify the strengthening micro-characteristics which enhance the material's interphasial reactions in order to improve the bonding properties of the matrix-reinforcement interface. This work focuses on the non-equilibrium segregation which arises due to imbalances in point defect concentrations set up around interfaces during non-equilibrium heat treatment processing of SiC particle reinforced aluminium matrix composites. The important factors affecting the heat treatment process are the temperature, the cooling rate, the concentration of solute atoms and the binding energy between solute atoms and vacancies. Aluminium – silicon – magnesium alloy matrix reinforced with varying amounts of silicon carbide particles were used in this study. Samples in the as-received and heat treated condition were examined by microstructural and microhardness analyses. Based on the analysis, it has been observed that the macroscopic mechanical behaviour of the composite is influenced by several factors including the manufacturing process, the processing conditions, the inter-particle distance, as well as the mean size and the percentage of reinforcement.
Micro Electro Discharge Machining of Polymethylmethacrylate (PMMA)/Multi-Walled Carbon Nanotube (MWCNT) Nanocomposites
Authors: Wan Yi , Kim Dave (Dae-Wook) , Park Young-Bin , Joo Sung-Kwan
Published: January 2019

This study investigated micro electro discharge machining (micro-EDM) of Polymethylmethacrylate (PMMA)/Multi-Walled Carbon Nanotube (MWCNT) nanocomposites. PMMA/MWCNT nanocomposites were fabricated using solution casting, in which MWCNTs were dispersed in the polymer-solvent solution via high energy sonication, followed by precipitation and hot pressing. MWCNT loading was varied to investigate the effect of electrical conductivity of nanocomposites on the machinability. Micron-size holes were created to study the material removal mechanism in micro-EDM. The electro discharge phenomena may occur between electrically conductive MWCNT and the tungsten electrode during the process. As a result, PMMA/MWCNT nanocomposite samples with 10 to 35 wt% MWNTs were able to be EDMed with proper machining conditions. It was observed that the material removal rate increases with increasing micro-EDM supply voltage and MWCNT loading on the material system. Both optical microscope and scanning electron microscope (SEM) were used to investigate the characteristics of the machined holes and nanocomposite surfaces.
Static and Dynamic Stability Analyses of the Symmetric Laminated Cantilever Beams
Authors: Kiral Binnur Goren
Published: January 2019

This article deals with the static and dynamic stabilities of cantilever symmetric laminated beams. In this study, three-dimensional finite element model based on the classical lamination plate theory is used. A computer code is developed using MATLAB software to perform the finite element analyses. Effects of the ply orientation, static and dynamic load parameters on the stability are examined. It is observed that ply orientations affect the location and the width of the instability regions.
Real-Time Observation of Damage Nucleation in 3D Braided Carbon/Carbon Composites
Authors: Kan Jin , Wei Liming , Meng Songhe , Xu Chenghai
Published: January 2019

The micro mechanisms of flexure damage at the notch tip in a three-dimensionally braided carbon/carbon composite (3D–C/C) were investigated in real-time through a Scanning Electron Microscopy. It was found that the damage was nucleated in the fibre bundle/matrix interface around the notch tip. The different damage modes were found in different directions of the 3D–C/C. The x-directional flexural specimens seem to be insensitive to the pre-notch while the z-directional flexural specimens seem to be sensitive to the pre-notch. Fibre yarns acted as an obstacle to crack propagation and it was necessary to increase the load to propagate the crack through the adjacent fibre yarn. Comparing with the x-directional flexural specimens, the forces could be better transmitted in z-directional flexural specimens because the fibres of z-direction bundles can tightly adjoin to each other.
Design of a Carbon Fiber Bicycle Stem using a Novel Internal Bladder Resin Transfer Molding Technique
Authors: Thouin Maxime , Ghiasi Hossein , Lessard Larry
Published: January 2019

The goal of this research is to design, analyze, and manufacture a carbon fibre bicycle stem that maximizes the use of carbon fibre composites. The stem is a part of the bicycle that connects the handlebar to the fork. The design is difficult due to the small size and complex geometry of the part, thus not obvious to conceive with a standard composite manufacturing approach. A novel approach using an inner bladder resin transfer moulding (RTM) technique is used to manufacture the bicycle stem. The design of the moulds incorporates some efficient devices to facilitate various steps in the manufacturing process. The resulting design is successful in terms of weight, stiffness, strength, and aesthetic properties. The developed technique used in this project can be applied as a possible solution to the design and fabrication of small, complex, hollow composite parts.
Effective Modulus of Single- and Multi-Walled Carbon Nanotubes in Melt-Compounded Polycarbonate Nanocomposites
Authors: Wang Zhujuan , Bilotti Emiliano , Peijs Ton
Published: January 2019

This study compares the reinforcing efficiency of multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) in polycarbonate (PC) films processed using melt-compounding followed by hot-pressing. The effect of carbon nanotube (CNT) type on composite properties is studied by means of dynamic mechanical analysis (DMA). Composite theory is used to analyse the results. It is found that, despite the good dispersion and interfacial interactions reported in the literature for PC/CNT nanocomposites, SWNTs and MWNTs efficiently reinforce PC only at nanofiller contents below 0.3 wt.% and 0.5 wt.%, respectively. Nevertheless, effective moduli of CNTs (in particular SWNT) close to the theoretical values were achieved for low nanofiller content.
Dielectric Spectroscopy and Tunability of Multi-Walled Carbon Nanotube / Epoxy Resin Composites
Authors: Špitalský Z , Georga S N , Krontiras C A , Galiotis C
Published: January 2019

The dielectric response of oxidized multi-walled carbon nanotube / epoxy resin composites, is investigated with respect to filler content concentration, over a wide temperature and frequency range. Specimens, below the percolation threshold, exhibit similar behaviour to that of the neat epoxy. Two relaxation modes are observed in the low temperature region, attributed to the re-arrangement of small parts of the polymer chain (γ-mode) and the reorientation of polar side groups (β-mode) respectively, where in the high temperature region the evolution of the α-mode is present. Direct current (DC) conduction follows the Vogel – Tamann - Fulcher equation as expected. The dielectric response of specimens, above the percolation threshold, follows the “Random Free Energy Barrier Model”. DC conductivity exhibits Arrhenius temperature dependence with two distinct regions. The activation energies of both regions were evaluated. The contact resistance between two adjacent carbon nanotubes was also calculated. The effective dielectric constant as well as the capacitance of the specimens, above the percolation threshold, can be modulated by means of an applied DC bias voltage.
Cutting Forces in Orthogonal Turning of Unidirectional Glass Fibre Reinforced Plastic Composites
Authors: Işık Birhan , Altan Erhan
Published: January 2019

Experimental investigation of machining is cost prohibitive. The number of parameters to control, the exhaustive material characterisation and the time consuming procedure to determine the mechanical responses like cutting forces restricts experimental studies. In this context, mathematical modelling can be a feasible tool for studying the various responses in machining. This paper presents an attempt to investigate orthogonal machining of unidirectional Glass Fibre Reinforced Plastic Composite (UD-GFRP) materials using mathematical modelling. The model entailing fibre orientation, shear strength, depth of cut, feed, friction angle and rake angle is constructed for investigating the tangential cutting and feed cutting force developed during machining. The numerical results are compared to the experimental results. The comparison indicates that the model provides satisfactory prediction of the cutting forces. The relations between process parameters are discussed.
Effect of Water Absorption on the Mechanical Properties of Pultruded Kenaf Fibre Reinforced Polyester Composites
Authors: Nosbi Norlin , Akil Hazizan Md. , Ishak Z.A. Mohd , Bakar Azhar A.
Published: January 2019

Kenaf fibre reinforced polyester composites (KFRPC) were prepared using pultrusion method with 30:70 matrix to fibre ratio. The effect of water absorption 260 days in distilled water at room temperature on the mechanical properties was evaluated. Test results indicated KFRPC strengths had decreased with increase in percentage of water uptake. The moisture absorption leads the degradation and creating poor stress transfer efficiencies resulting in a reduction of mechanical properties.
Analytical and Experimental Study of Flexural Strengthening of RC Members using Mechanically Fastened FRP Strips
Authors: Papalou Angeliki , Triantafillou Thanasis C.
Published: January 2019

The main objective of this work is to investigate the behaviour of reinforced concrete members strengthened for flexure using mechanically fastened fiber reinforced polymer (FRP) strips. Experiments were conducted on strengthened reinforced concrete beams loaded to failure with an increasing load in four-point bending. An analytical-numerical model was developed predicting the behaviour of the strengthened concrete beam and reproducing its large ductility before failure.
Synthesis and Characterization of High-Pure Nanocrystalline Forsterite and its Potential for Soft Tissue Applications
Authors: Razavi Kamran Amir Hossein , Moztarzadeh Fathollah , Mozafari Masoud
Published: January 2019

This research reports the successful synthesis and formation of nanocrystalline forsterite (Mg2SiO4) powder by sol-gel method as a second phase for using in soft tissue engineering nanocomposite scaffolds. As high-pure and nanostructured forsterite is expected to have better biocompatibility and bioactivity, heat-treatment process was done on the synthesized nanopowder to obtain high-pure nanocrystalline forsterite. However, during the synthesis of forsterite, it is very difficult to avoid the formation of MgSiO3 (enstatite) and MgO (periclase). Moreover, increasing of the treatment temperature resulted in the improvement of the purity of the sample and the formation of single-phase forsterite. The TEM micrograph of the synthesized forsterite after the final heat-treatment process indicated that the particles were nearly elliptical shaped morphology and the size was in the range of 10 to 20 nm. This research also demonstrated that the pure forsterite did not show any signs of toxicity after 48 h with fibroblast cells and the cytotoxic scale was measured as zero. In addition, the combined results of the microstructural and biological studies suggested that this material exhibit good potential and biocompatibility for soft tissue engineering applications.
Electric and Magnetic Properties of Recycled NdFeB-Natural Rubber Composites
Authors: Jantarattana P , Sirisathitkul C , Hunyek A , Maensiri S
Published: January 2019

Electromagnetic properties of natural rubber (NR) incorporated with recycled neodymium-iron-boron (NdFeB) powder from 0 to 120 phr by the two-roll mill technique were studied. The remanent magnetization, coercive field and logarithmic value of the electrical permittivity were linearly increased with the NdFeB loading according to the rule of mixture suggesting that interactions between NdFeB clusters were moderate. The addition of 120 phr NdFeB also increased the reflection loss of NR.
Shear Properties of a Glass-Fibre/Vinylester Composite Cured with High Intensity Ultraviolet Light for use in Automated Manufacturing Processes
Authors: Di Pietro A. , Compston P.
Published: January 2019

This work presents preliminary results on the potential for rapid curing of a glass-fibre/vinylester composite with high-intensity ultraviolet (UV) light. Two 10-ply laminates were manufactured by hand lay-up with a resin formulated with a photo-initiator (Derakane 411-350 vinylester and Ciba Specialty Chemicals Irgacure 819 photo initiator). For the first laminate, all 10 plies were laid-up at once, then cured in approximately 4 minutes using a high intensity 200 Watt mercury short arc UV light. For the second laminate, each ply was laid and then exposed for less than 1 second to the same UV light. Testing of the resin-sensitive interlaminar shear strength showed no difference in properties between the two laminates. Furthermore, the shear strength was comparable to the properties of laminates cured via traditional heat curing methods with a typical 24-hour room temperature cure followed by a thermal post-cure. The study shows that a ply-by-ply approach to lay-up and partial cure, which is the likely procedure for automated ply-by-ply placement process, such as automated fibre placement, does not affect laminate performance.
Influence of Projectile Nose Shape on Ballistic Limit and Damage to Glass/Vinyl Ester Composite Plates
Authors: Sasikumar M. , Sundareswaran V.
Published: January 2019

In the recent past, the substantial structural strength, light weight and stiffness properties of polymer based composite materials find its application in aircraft and automotive structures at prodigious rate. Fibre glass Reinforced Plastic (FRP) composites are partially elastic and brittle. The present study evaluates the ballistic limit, energy absorbed and the damage area caused by different projectile nose shapes on the composite plates made of glass fibre and vinyl ester resin with the orientation of (0/90)s. The number of plies in the plates is varied to 4, 6 and 8 and thus lead to different thicknesses. The projectile nose geometry is varied (hemispherical, conical, truncated conical, ogival and truncated ogival) to have realistic effect on the impact. The influence of projectile nose shape over ballistic limit is found experimentally and compared with the analytical predictions by H. M. Wen [ 5 , 6 ]. The ballistic limit, perforation mechanism, energy absorption at ballistic limit and the damage area at ballistic limit velocity has been studied. The influence of thickness of the composite plate over the ballistic limit have also been discussed. It is found that the truncated conical nose shaped projectile resulted in highest ballistic limit and largest damage area dominated by delamination. Experimental results showed that the analytical method [ 5 , 6 ] could satisfactorily predict the ballistic limit.
Minimizing Thickness Variation in the Vacuum Infusion (VI) Process
Authors: Yenilmez Bekir , Akyol Talha , Caglar Baris , Sozer E. Murat
Published: January 2019

In the Vacuum Infusion (VI) process, the thickness of a composite part changes as the compaction pressure on the vacuum bag and reinforcing fibre preform changes. Pressure and thickness were monitored along a 1D resin flow using pressure transducers and non-contact laser displacement sensors. To decrease the thickness variation, control actions were taken by adjusting the injection conditions, such as opening/closing gates/vents, changing pressure of them in the post-mold filling stage and bleeding out the excess resin. The control actions were taken based on an available compaction/decompaction database for the fabric type used. Compared to the case study with no control action other than bleeding, a better job was done in the controlled case study by decreasing the maximum thickness variation from 5.44% to 0.39%. A coupled flow and compaction model qualitatively verified the pressure and thickness distributions for both filling and post-filling stages.
Investigation of Free Vibration Response of E-Glass/Epoxy Delaminated Composite Plates
Authors: Ercopur Turan , Kiral Binnur Goren
Published: January 2019

This paper deals with the finite element analysis of free vibration response of the delaminated composite plates. Free vibration analysis is performed by using ANSYS commercial software developing parametric input files. Natural frequency values and associated mode shapes of E-glass/epoxy composite delaminated plates are determined. Effects of delamination shape, dimension and location on the natural frequency and associated mode shapes are investigated and for the purpose of the observing the effect of the boundary conditions, cantilever and clamped-pinned delaminated composite plates are taken into consideration. Comparisons with the results in literature verify the validity of the developed models in this study. It is observed that the natural frequency decreases in the existence of the delamination and level of the decrease depends on the dimension, shape and location of the delamination.
The Meshless Element Free Galerkin Method for Buckling Analysis of Simply Supported Laminate Composite Plates
Authors: Pekbey Yeliz , Maleki Farshid K. , Yildiz Hasan , Hesar Goudarz G.
Published: January 2019

A meshless element free Galerkin method (EFG) is presented to analyze the buckling of laminated composite plates using the classical (Kirchhoff's) plate theory (CPT) formulation. In the meshless EFG method, the moving least-squares (MLS) technique which does not satisfies the Kroneckar delta feature is used to set up the shape functions. The accuracy and the efficiency of the meshless EFG method are thus demonstrated by the numerical analysis of laminated composite plates with simply supported boundary conditions. Effects of the number of layers, ply orientations, the length-to-width ratio and modulus ratio on the dimensionless buckling loads are investigated. The results obtained by the EFG method are compared with those obtained by the CPT and the finite-element method (FEM). EFG results have good agreements with the analytical solutions. Comparison of results with the CPT as well as the FEM suggests that the meshless element free Galerkin method (EFG) yields an effective solution method for the analysis of laminated composite plates.
Strain Rate Effects on Tensile and Compressive Behaviour of Woven-Knitting Glass/Epoxy Composites
Authors: Aktas Mehmet , Balcioğlu H. Ersen , Külahli Gürhan
Published: January 2019

The main purpose of this study was to investigate the tensile and compressive behaviour of woven-knitting glass/epoxy composites under low strain rate by using UTEST testing machine with capacity of 50kN. The strain rate values were selected as 0.005, 0.0005 and 0.00005s−1. The effect of knitting direction as wale, course and 45° and knitting structure as rib and milano on the tensile and compressive behaviour of woven-knitting glass/epoxy composites under low strain rate was also discussed. The woven-knitting composite samples were tested under uni-axial tensile and compressive loading. The woven-knitting composites have eight layer with woven fabric (W), rib (R) and milano (M) knitting fabrics as (W2/R2)S and (W2/M2)S. The woven-knitting composites were manufactured by hand lay-up method. The fibre volume fraction and thickness of manufactured woven-knitting composites were measured 65% in weight and 2.9mm, respectively. The experimental results showed that the tensile and compressive properties of woven-knitting glass/epoxy composites decrease from 0.005 s−1 to 0.00005s−1. The tensile properties in all directions of plate with rib knitting were obtained higher than the plate with milano knitting. However, the highest compressive properties were obtained from plate with rib knitting in course direction.
An Experimental Investigation of Curvature Effect on the Laminated Composites at Low Velocity Impact
Authors: Belevi Melih , Koçhan Cemal , Yirtimci Arif Yaşar Ozan
Published: January 2019

The aim of this study is to investigate experimentally effects of curvature, fibre orientation and ageing process on the low velocity impact behaviour of E-glass/epoxy composites. To investigate ageing effect, the half of the specimens have been left to dry at room condition and the other half was aged by the salt spray test. An apparatus was designed and produced to conduce impact tests of curved specimens. 20 J impact energy was used for experiments.
Morphological and Microstructural Property Comparison of Bulk and Aligned Cvd-Grown Carbon Nanotubes
Authors: Mei Hui , Bai Qianglai , Dassios Konstantinos , Li Haiqing , Cheng Laifei , Galiotis Costas
Published: January 2019

Carbon nanotubes are one-dimensional materials found in various forms, the most important of which are bulk unordered carbon nanotubes of lengths of few microns and aligned tubes regularly a few millimeters long. Differences in length, orientation, alignment, nanotube graphitization and purity will influence the eventual performance of the material. Herein four characterization methods are used to characterize and compare bulk and aligned carbon nanotubes. Results show that the diameters of the millimeter-long aligned carbon nanotubes are approximately 60 ∼ 80 nm with thick nanotube walls of about 25–30 nm, while the diameters of the bulk carbon nanotubes are about 15–20 nm with much thinner walls. The aligned carbon nanotubes have significantly larger graphitization degrees, higher purity and greater orientation than the bulk carbon nanotubes that tend to self-agglomerate under no external stimulus. Silicon carbide matrix nanocomposites reinforced by the aligned carbon nanotubes were found to be denser that those reinforced by the bulk carbon nanotubes and also exhibit extensive, uniform, and long pullout of carbon nanotubes.
Experimental Investigation on the Crashworthiness of Braided Glass/Epoxy Tubes Subjected to Axial Impacting
Authors: Zhang Ping , Gui Liang-Jin , Fan Zi-Jie , Liu Jing-Yu
Published: January 2019

This paper presented an experimental study on the low-velocity impact response of triaxial braided composite circular tubes, which were fabricated with S-glass/epoxy composite. The impact responses were recorded and analyzed in terms of impact load-displacement curves and specific energy absorption. In addition, four basic failure modes called delaminating, splaying, fragmental fracture and progressive folding were founded. The levels of the mean impact load and specific energy absorption (SEA) are determined by the energy absorption mechanisms, which are related to the dominant failure modes of the tubes. In general, delamination which exhibits the poor energy absorbing performance is the dominant failure mode for all the specimens. Impact test results showed that all three types of tubes had almost the same SEA. Compared to the quasi-static test results, the first peak load and the mean load decrease at about 50% and 10% respectively, SEA generally decreases at an average level 10%.
Investigations on the Effect of Flyash on the SiC Reinforced Aluminium Metal Matrix Composites
Authors: RameshKumar K.A. , Balamurugan K. , Gnanaraj D. , Ilangovan S.
Published: January 2019

The Al-SiC composites have been prepared by using liquid sand casting technique with aluminium as the base material with 10 % SiC particulates by weight. Flyash content is varied and the abrasive wear study has been conducted on a Pin-on-Disc method. Dry sliding wear characteristics of the samples were investigated in detail. Vicker's microhardness test was carried out for the Al-SiC metal matrix composites. Scanning electron microscopic (SEM) analysis was carried out for the worn out surface to visualize the surface phenomena. The results indicate that the increase in flyash composition increases the wear resistance characteristics. The results have been discussed and are outlined in detail.
A New Method for Calculating the Stiffness of Filament Wound Composites considering the Fibre Undulation and Crossover
Authors: Shen Chuangshi , Han Xiaoping , Guo Zhangxin
Published: January 2019

The filament-winding process leads to fibre undulations and the nonorthogonality of crossover geometries into thin-shell cylinders. In this paper, the micromechanical geometry in the fibre crossover regions of filament-wound cylinders is first identified. A three-step method is then presented for calculating the stiffness of filament winding composites. In Step 1, the 3D stiffness for the undulating layer is converted to an effective 2D stiffness via the two angles, namely the filament winding angle and the inclination angle due to the fibre undulation. In Step 2, the lamination theory is used to obtain the local laminate stiffness as a function of the undulation direction and the stiffness constants through the numerical integrating and averaging along the length of undulation. In Step 3, the whole stiffness of filament winding composites is calculated through the transformation from the principal coordinate axis to the direction of filament-winding. The effects of the filament winding angles, winding sequence and filament undulating region on the stiffness are finally discussed.
Damage Evaluation of Carbon-Fibre Reinforced Polymer Composites Using Electromagnetic Coupled Spiral Inductors
Authors: Li Z. , Haigh A. D. , Soutis C. , Gibson A.A.P. , Sloan R. , Karimian N.
Published: January 2019

This paper presents the application of electromagnetic coupled spiral inductors for the non-destructive evaluation of carbon-fibre reinforced polymer (CFRP) plates. Three types of representative damage in carbon fibre composites are evaluated, i.e. barely visible impact damage (BVID), subsurface defects and internal micro-cracks. This work indicates that the size and location of the subsurface defects can be quantitatively assessed from the signal data acquisition.
Investigation of Graphite Nano Particle Addition on the Physical and Mechanical Properties of ZA27 Composites
Authors: Dalmis R. , Cuvalci H. , Canakci A. , Guler O.
Published: January 2019

The physical and mechanical properties of composites consisting of ZA27 alloy reinforced with nano-sized graphite particles were investigated with the main objective of understanding the effect of the nano particulate reinforcement. These properties were determined by measuring the density, hardness and tensile strength values. The microstructure of the ZA27-Graphite (Gr) nanocomposites was investigated using a scanning electron microscope (SEM). The results indicated that density values of nano graphite added nanocomposites (GANs) decrease with increasing graphite rate while porosity ratio increases. Also the UTS and Brinell hardness values decreased with increasing graphite content.
Frequency Characterizations of Epoxy/CNTs Composites under Compression at Different Strain Rates
Authors: Ma Pibo , Chang Yuping , Jiang Gaoming
Published: January 2019

This paper reports the compression behavior of epoxy composites with various carbon nanotubes (CNTs) contents, under quasi-static and high strain rate compression. The compression behaviours of epoxy composites with various CNTs contents under quasi-static and high strain rate compression were compared and analyzed in the frequency domain using the fast Fourier transform (FFT) method. The results show that the compression behavior, amplitude spectrum and phase spectrum of the epoxy/CNTs composite are strain rate sensitive. The epoxy/CNTs composites can absorb higher energy in a specific frequency range.
The Study on Timber Pier Columns Strengthened with Cfrp Hoops in Ancient Architecture
Authors: Xiong X Y , Lu X X , Xue R J
Published: January 2019

Timber structure is the mainstream method of ancient Chinese architecture. However due to the effect of weathering and long history, it was badly damaged. Therefore, the protective repairing is imminent. The traditional reinforcement method of pier columns strengthened with iron sheet presents unsatisfactory performance in recovering the bearing capacity, and the study on Carbon Fibre Reinforced Plastics (CFRP) material applying in strengthening pier column is relatively lacking. This paper studied the mechanical properties of 20 timber columns, 17 of which used the CFRP for reinforcement, and one specimen is strengthened with iron sheet. With the maximum bearing capacity of reinforcement columns with CFRP recovering up to 103.22%, the research proves reasonable arrangement of CFRP hoops and suitable strengthening quantity of CFRP could get commendable reinforcement results. Finally, considering the effect of the pier type on the bearing capacity of pier columns, this paper puts forward a more accurate and universal formula compared to Su model, which provides theoretical foundation for restoration projects of ancient architecture.
Molecular Dynamics Simulation Study of Eucommiaulmoides GUM/AG Nanoparticle Composites
Authors: Li Fei-Zhou , Lu Zhen-Lin , Xi Yuntao , Wang Xin-sheng , Zhu Ming-qiang
Published: January 2019

A study of eucommia ulmoides gum (EUG)/Ag nanoparticle (NP) composites by molecular dynamics (MD) simulations to understand their structure, polarizability, thermodynamic properties, and mechanical properties is proposed. The effects of simulation temperature and Ag NPs size on these parameters were also studied. The results revealed that the composites exhibited an isotropic amorphous structure, and the distribution uniformity of the Ag NPs was enhanced by changing the simulation temperature. Several atoms of the Ag NPs were in an amorphous state, and a polarized layer was observed on the interface between the Ag NPs and the eucommia ulmoide matrix. The interface size increased as the temperature increased and nanoparticles size decreased. The isochoric heat capacity and thermal pressure coefficient of the EUG/Ag-NP composites exhibited significant size effects and improved thermal interferences, which indicated that the presence of the Ag NPs had a positive effect on the mechanical properties of the EUG.
Experimental Research on AFRP Reinforced Recycled Steel Tube Columns Subjected to Axial Compression
Authors: Hou Min , Dong Jiangfeng , Li Lang , Yuan Shucheng , Wang Qingyuan
Published: January 2019

In order to make an effective use of the recycled aggregate concrete (RAC), a total of six steel tube RAC columns and six basalt fiber (BF) reinforced RAC columns, including six columns that were externally strengthened with aramid fiber reinforced polymer (AFRP) sheets, were fabricated and tested. This were to provide a strengthening solution to upgrade the load carrying capacity, ductility and rigidity of the RAC filled steel tube columns. Besides, the recycled coarse aggregate (RCA) replacement ratios for production of RAC was analyzed. The results show that the load carrying capacity and ultimate displacements of the RAC filled ST columns could be improved greatly by adding of basalt fiber, especially for the specimens with 50% and 100% RCA replacement ratio. The similar result was also found for the specimens strengthened with AFRP reinforcement, along with the stiffness of the columns were enhanced obviously. Moreover, the highest improving on the load carrying capacity, stiffness and ultimate displacement was found in the specimens both reinforced by adding of BF and strengthening of AFRP. However, the failure modes of the specimens with BF reinforced RAC gave a higher deformability than the one with AFRP strengthening arrangement.
Optimizing Drilling Induced Delamination in GFRP Composites using Genetic Algorithm& Particle Swarm Optimisation
Authors: Kalita K. , Mallick P. K. , Bhoi A.K. , Ghadai K.R.
Published: January 2019

Composites are widely used in several applications ranging from automotive to aircraft industry due to their high strength to weight ratio. More often than not drilling on these composite laminates are conducted to serve some functional or aesthetic requirement. Delamination caused due to drilling pose a severe problem to the integrity of the structure. It is often not possible to develop an exact mathematical model to predict the delamination associated with such drilling. So, in this paper, an empirical model is developed based on the extensive experiments performed on polyester composite reinforced with chopped fibreglass. To account for the various parameters a Box-Behnken design of experiments is conducted for four parameters (material thickness, drill diameter, spindle speed, and feed rate) each having threedistinct levels. Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) techniques are then used for predicting the global optimum (minimum delamination factor). The performance of both GA and PSO in terms of predicting the global optimum is found to be same. However, PSO converged much faster and required far lesser computational time.
Influence of Natural Weathering Conditions on the Natural Frequency Change of Woven Carbonfibre Reinforced Composites
Authors: Kaya Ali Ihsan , Kisa Murat , Ozen Mustafa
Published: January 2019

This paper reports the effect of three different aging natural conditions on natural frequencies of woven carbon fibre reinforced epoxy composites. Composite beams were aged for a year and fivesamples of composite beams were examined for vibration tests within 3 months interval. Validation of test method was done by using ANSYS. Results show that a combination of water and temperature natural aging condition has the most severe effect on composite beams.
Interfacial Bonding Mechanism Ofaluminium and Steel Composites
Authors: Yang Xian , Weng Hao , Tang Chao-lan
Published: January 2019

The research on singular material is gradually converted to composite material which serves to rectify weaknesses possessed by each constituent when it exists alone. Experiments on Al-alloy 4A60 and 08Al steel plate compounded by cold roll bonding were conducted to analyze the bonding mechanism of the interface during the composite process of laminated metal. SEM, EDS, and laser confocal microscope were used to observe the interface and section of composites while the bonding strength was tested by universal tensile machine. The result showed that bonded metal's surface microtopography, reduction and diffusion annealing were the most critical influences on the bonding of composites, and the roll bonding mechanism of 4A60/08Al composite was divided into three stages: 1) Physical contact. Two component layers were mechanically occluded by the rolling pressure, the bonding strength was low; 2) Metallic bonding. The oxide layer and the hardened layer covered on the metal surface break which made the two component fresh metals to full contact, chemical action happened and metallic bonding formed when the interatomic distance reached a certain stage, the bonding strength increased; 3) Metallurgical bonding. In the subsequent annealing treatment, the bonding strength significantly increased because the diffusion of metal atoms at the interface.
Characterization of Deformation States after Thermoforming of Long Discontinuous Fiber Composites (LDF™) by Using Ultrasonics
Authors: Schuster J , Friedrich K
Published: January 2019

Long Discontinuous Fiber - Composites (LDF™) were developed for thermoforming. This material with 5 cm long aligned fibers in a PEKK matrix has similar static mechanical properties as continuous fiber systems. A method is described to determine the elongation created by thermoforming without post-compression based on ultrasonic evaluation. During the experiments, a correlation between the plastic deformation of the material and the generated voids in the material was found.
A New Approach in Analysing the Three-dimensional Behaviour of a Composite Plate
Authors: Isometsä J. , Sjölind S-G. , Pramila A.
Published: January 2019

The bending of a thick composite plate is studied by using a 2-d plate element with a stiffness matrix derived by a 3-d solid model for a typical element. Constraint equations are used to ensure full displacement continuity between adjacent plate elements. After solving the global behaviour by 2-d elements the local behaviour is studied by using the 3-d model of the typical element. The approach is verified by comparing the full 3-d stress state obtained with an available analytical solution.