bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Inter-Fibre Distance on Energy Transfer in Unidirectional Composites Containing Ultrasonic Waves
Authors: Hasheminejad Seyyed M. , Miri Amir K.
Published: January 2019

Interaction of time harmonic monochromatic anti-plane (SH) waves with a pair of parallel unidirected elastic cylindrical fibres embedded in an unbounded elastic matrix is considered. The classical method of separation of variables along with the appropriate wave field expansions, the pertinent boundary conditions, and the translational addition theorems for cylindrical wave functions are employed to obtain a series solution in terms of Fourier coefficients. The presented development is illustrated with numerical examples in which the fibres are insonified at end-on/broadside incidence for a relatively wide range of nondimensional frequencies. Particular attention has been focused on the effects of lateral fibre spacing on energy transfer between the fibres and matrix. The numerical results reveal that, while inter-fibre scattering (interference) has a small influence on the normalized fibre energies for broadside incidence at all frequencies, it has a considerable impact on the energy distribution for end-on incidence (fibres positioned in the eclipse configuration) at intermediate and high frequencies. The proposed model can complement acousto-ultrasonic (AU) techniques in non-destructive evaluation of unidirectional fibre-reinforced composite materials which is generally hampered by the highly dense concentration of the fibres. Limiting case is considered and fair agreement with a well-known solution is established.
Influences of Fibre Surface Treatment and Solvent Species on RTMED Silica Fibre/Phenolics Composites
Authors: Wang Baichen , Huang Yudong , Chen Ping , Gao Yu
Published: January 2019

In this study the effects of solvent species and silane coupling agent on the resin transfer moulded (RTMed) silica fibre/phenolics composites were investigated. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and wettability measurement were carried out. The interlaminar shear strength (ILSS) measurements and morphological observations of the silica fibre/phenolics composites were also performed. The interactions occurring between silica fibre and the components of phenolics solution affect the dynamic adsorption behaviour of phenolic resin onto fibre reinforcement. The competitive adsorption of solvent onto silica fibre suppresses that of phenolic resin. Fibre surface silanization with γ-aminopropyl-triethoxysilane (γ-APS) leads to the improvement of mechanical interfacial properties of silica fibre/phenolics composites on one hand and decreases inhomogeneities of resin distribution and mechanical interfacial properties of the RTM product on the other. For the first time it has shown that the RTM process of silica fibre/phenolics composites is highly solvent dependent. Phenolics form distribution gradient in RTM mould with respect to isomeric composition under the effect of solvent, which result, to varying extent, in the inhomogeneity of void content and thus ILSS of the resulting product. Our work gives an insight into the role of organic solvent in RTM processing and this will help in choosing the best possible solvent for the solution impregnation system.
Effect of Sewing Threads on Interlaminar Shear Strength and Flexural Bending Strength of Stitched Non-Crimp Carbon Fabric Laminates
Authors: Mitschang Peter , Ogale Amol
Published: January 2019

Interlaminar shear strength and flexural bending strength of stitched and non-stitched carbon fibre reinforced polymer (CFRP) laminates were studied with reference to three different sewing threads. The preforms were stitched through-the-thickness by two different hybrid carbon fibre threads and a Zylon (polyphenylen-2,6-benzobisoxazol, PBO) thread with 16 stitches/cm2 stitch density. The short beam interlaminar shear strength of the laminate increases where as flexural bending strength of the laminate shows mixed results depending on the stitching direction. Carbon fibre threads show relatively less positive influence on the laminate properties than the PBO thread. The results of this study differ partly from the literature studies.
Mechanical Properties of Compression Moulded Glass and Jute Fibre Reinforced Polypropylene
Authors: Sommer Marcel M. , Galan Isabel , Schledjewski Ralf
Published: January 2019

This work is concerned with the evaluation of the mechanical properties of compression moulded fibre reinforced polypropylene composites. Herein commercial glass and jute fibre polypropylene composites pellets were mixed to the content ratio varying in a range from 0 to 30 weight-% each, but to a constant reinforcement fraction of 30 weight-% in total. The different ratios were analyzed in mechanical testing to gain an optimum. The evaluation is proceeded with regard to the densities. The results obtained show how to use jute fibres for more than only a filler. Aimed applications are components where not very high mechanical properties are demanded, but where certain elasticity, weight, price, and environmental impact are important issues, too.
A Review of the Pull-Out Mechanism in the Fracture of Brittle-Matrix Fibre-Reinforced Composites
Authors: Dassios Konstantinos G.
Published: January 2019

The current work addresses the role of damage mechanisms such as interfacial debonding, crack deflection, bridging and sliding during fracture of a brittle-matrix fibre-reinforced composite with respect to their energy dissipation capacity and their impact on the pull-out mechanism. The aim of the paper is to explain why fibre failure is preferably concentrated within the matrix environment to give rise to the pull-out mechanism and not within the crack flanks where fibre stress is maximum. Two approaches, mechanics of materials and fracture mechanics, are invoked to demonstrate that pull-out is triggered and dominated primarily by the fibres’ surface flaw distribution rather than by fibre strength. The origins of pull-out are also explained in terms of statistics and the identified failure pattern of fibres in composites is discussed in view of its implications to experimental practice. The implications of the findings are summarized in a current need for a deeper investigation into the micromechanics of reinforcement in composites, the role of surface flaws and the interface as well as in the competing roles of strength and flaw size.
Computer Simulation of Thermal Residual Stress of Carbon Fibre/Ppesk Composite
Authors: Lu Chun , Chen Ping , Yu Baijie
Published: January 2019

A 3-D FEA technique was employed to analyze the thermal stress distribution in a carbon fibre/PPESK composite. The zone close to the free surface and to the inner zone were examined, and the parabolic failure criterion was used to predict the potential failure zone of the composite. The obtained results indicated that the maximum residual stress on the fibre surface was located at the fibre/matrix interface with the longest distance between the fibres and the maximum matrix residual stress was located at the composite inner zone with the closest distance between the fibres. The potential failure mechanism in the free-end zone was fibre/matrix interfacial debonding, while the potential failure mechanism in the inner zone was matrix cracking.
Preparation of Chitosan/Carbon Nanotubes Composites
Authors: Liu Ai-hong , Sun Kang-ning , Li Ai-min
Published: January 2019

In this paper, multi-walled carbon nanotubes (CNTs) were first purified and oxidized by blend acid composed of vitriol and nitric acid, and then surface decorated with biopolymer chitosan via a controlled surface deposition and crosslinking process. The results showed that the diameter of CNTs became thicker because the surface of CNTs was covered with chitsoan, and the dispersion of CNTs was improved.
Study of the Behaviour of Glass-Fibre Fabric Reinforced PEI Subjected to Thermal Loads. Influence of Aging
Authors: Chacon L. , Arguelles A. , Vina I. , Castrillo M.A. , Vina J.
Published: January 2019

The behaviour of specimens from a composite made of a thermoplastic matrix PEI (polyetherimide) reinforced with glass-fibre fabric was studied. The material was exposed to accelerated aging in a climatic chamber at 70°C and a relative humidity of 95%, during periods of time of 10, 30, 60, 90, 180 and 360 days. The specimens were subsequently subjected to isothermal tests at 50, 100 and 150°C during 250, 750 and 2000 minutes with a constant stress of 40% of the material's tensile strength (obtained to ambient temperature). These three temperature values were selected from the results obtained in tensile tests carried out on specimens subjected to different temperatures ranging between ambient temperature and that of glass transition. In addition, the behaviour of the aged specimens was compared with the original material, using the same parameters of temperature, time and constant stress. An increment in tensile strength with regard to the original material was observed.
Filtration of Particles through a Single Layer of Dual Scale Fibrous Porous Media
Authors: Chohra Mourad , Advani Suresh G , Yarlagadda Shridhar
Published: January 2019

Functionally Graded Composites exhibit properties or functions within the material that vary gradually or in a stepwise manner without a recognizable boundary. One technique to manufacture Functionally Graded Polymer Composites is by a resin infusion process. In this process, preforms of glass, aramid or carbon fabric are stacked in a closed mold and resin with suspended micron-sized particles is injected into the mold. The preforms are usually fabrics with yarns or bundles of thousand or more micron-sized fibres woven, stitched or knitted together. This architecture gives rise to a bimodal distribution of pore sizes; the larger pores in between the bundles and smaller ones within the bundles. The dual-scale nature of the fabric creates a network of pore sizes through which the resin will flow to cover the fibres, but the infiltration and the final concentration distribution of the particles will establish the gradient of the properties in the composite. In this paper, we present a model to predict the concentration distribution of particles within this dual-scale fibrous porous media infused under a constant pressure drop. The approach uses Darcy's law and accounts for lowering in the permeability value due to the particle entrapment in the available pores. Experiments are conducted and the concentration of the particles in the fabric is measured. The results compare well with the predictions despite many assumptions made in the model. A non-dimensional analysis is conducted and a parametric study explores the influence of critical non-dimensional parameters on the filtration efficiency.
A Comparison of Ply-Level and Sublaminate-Level Scaling Offibre-Metallaminates with In-Plane Dimensions
Authors: Carrillo J. G. , Cantwell W. J.
Published: January 2019

The work presented in this paper investigates size effects in 2D-scaled (in-plane dimensions) FMLs based on a self-reinforcing polypropylene composite and aluminum. Two different scaling approaches are adopted in this study, these being ply-level scaling using laminates with a stacking sequence of [Aln, 0°/90°n]s and sublaminate-level scaling involving a stacking sequence of [Al, 0°/90°]ns where n =¼, ½, ¾ and 1, representing the increase of in-plane dimensions. An apparent increase in strength for ply-level specimens was observed with scale size while sublaminate-level scaling did not present scaling effects.
Modification of C/SIC Composites using Partial Boron Carbide Self-Sealing Matrix by ICVI
Authors: Liu Yongsheng , Zhang Litong , Cheng Laifei , Yang Wenbin , Xu Yongdong
Published: January 2019

C/SiC composites were modified using partial boron carbide (BCx) as matrix by isothermal chemical vapour infiltration technique (ICVI). SEM results showed that the multilayer SiC-BCx matrix exist among fibre bundles, nevertheless there were still SiC matrix among monofilaments. The modified composites hold better fracture roughness than the conventional C/SiC composites, although the other mechanic properties of the two kinds of composites were similar. The pull-out of multilayer matrix was the main factor of the increase of fracture toughness. Compared with the C/SiC composites coated with SiC/SiC/SiC, SiC/B-C/SiC or SiC/B/SiC coatings, the lower weight loss and higher residual strength of the modified composites were demonstrated. Furthermore, the weight gain and strength increase of the modified composites were found after oxidation at 1000°C and 1300oC due to the self-sealing of the micro-cracks and pores as shown in SEM results.
Thermal Elastic-Plastic Stress Analysis of an Aluminium Composite Disc under Linearly Decreasing Thermal Loading
Authors: Topcu Muzaffer , Altan Gurkan , Callioglu Hasan , Altan Burcin Deda
Published: January 2019

In this study, an elastic-plastic thermal stress analysis of an orthotropic aluminium metal matrix composite disc with a hole has been investigated analytically for non-linear hardening material behaviour. The aluminium composite disc reinforced curvilinearly by steel fibres is produced under hydraulic press. The mechanical properties of the composite disc are obtained by tests. A computer program is developed to calculate the thermal stresses under a linearly decreasing temperature from inner surface to outer surface. Elastic, elastic-plastic and residual thermal stress distributions are obtained analytically from inner surface to outer surface and they are presented in tables and Fig. s. The elastic-plastic solution is performed for the plastic region expanding around the inner surface. The magnitude of the tangential stress component has been found out in this study to be higher than the magnitude of the radial stress component. Besides, the tangential stress component is compressive at the inner surface and tensile at the outer surface. The magnitude of the tangential residual stress component is the highest at the inner surface of the composite disc.
Microstructural Characterization and Tensile Behaviour of a 3D Braided C/SiC Composite Fabricated by Chemical Vapour Infiltration
Authors: Wang Yiqiang , Zhang Litong , Cheng Laifei , Ma Junqiang
Published: January 2019

The microstructure of a 3D C/SiC composite was characterized and the tensile behaviour was investigated in conjunction with acoustic emission (AE) technique. A computer model of the fibre architecture was generated for visualization and further stress analysis. The results show that the stress-strain curves exhibit mostly nonlinear behaviour with four distinguishable regions, which compare well with the AE characteristics. Microstructural observations reveal the superficial matrix cavities and large inter-bundle pores due to the 3D braiding fibre architecture. The failed specimens show ragged fracture surfaces and extensive fibre pullout, as well as interfacial debonding.
Easy Synthesis and Efficient Photocatalytic Activities of ZnO/Mordenite Composite
Authors: Wang Lingling , Wu Hong , Xu Jinquan , Li Ling
Published: January 2019

A new nanoporous material consisting of nano-ZnO particles designed within the cavities and frameworks of mordenite has been synthesized and characterized. The synthesis involves a precipitation of Zinc oxide from Zinc nitrate solution on mordenite by salt melting procedure which is in the present of Nitric acid. These materials were characterized by BET surface area, XRD, UV-Vis-DRS, AAS, and HRTEM. The characterization of ZnO/mordenite composite clearly shows that some of nano-ZnO particles were encapsulated within the cavities and frameworks of mordenite. The photodegradation of methyl orange which occurs in the present of ZnO/mordenite composite is a little superior to that of Degussa P25 TiO2.
Shear Strengthening of RC Beams Subjected to Cyclic Load Using CFRP Strips
Authors: Sakar Gokhan
Published: January 2019

An experimental investigation was conducted to study the effect of composite carbon fabric shear reinforcement on the ultimate strength and behaviour of reinforced concrete beam. Shear deficient specimens were strengthened by using side-bonded and wrapped CFRP straps. Eight beams were fabricated and tested under the cyclic loads. The main objective of the study is to obtain ductile flexural behaviour from the shear deficient RC beams. To verify the reliability of shear design equations and guidelines, experimental results were compared with all common guidelines and published design equations.
Analytical Modeling of Circular Glare Laminated Plates under Lateral Indentation
Authors: Tsamasphyros George J. , Bikakis George S.
Published: January 2019

In this paper analytical solutions are derived to predict the static response of thin circular clamped GLARE fibre-metal laminated plates under the action of a lateral hemispherical indentor. The load-indentation curve is calculated along with the first failure load and deflection due to glass-epoxy tensile fracture. The Ritz method is employed with one, two and three-parameter Ritz approximation functions. The derived formulas are applied to GLARE 2-2/1-0.3 and to GLARE 3-3/2-0.4 circular plates with various diameters. The results converge satisfactorily in all examined cases. The calculated load-indentation curve and the first failure agree well with published experimental data for the case of a GLARE 2-2/1-0.3 plate with a radius of 40 mm (failure load within 7% and failure deflection within 3%). The same load-indentation curves are also calculated using ANSYS and by comparison to FEM results the validity of the analytical model is further verified. No analytical solution of this problem is known to the authors.
Error Assessment in Permeability Measurement Using Radial Flow Method
Authors: Gommer Frank , Lomov Stepan , Vandenbosche Kelly , Verpoest Ignace
Published: January 2019

Permeability values measured on textile reinforcements with different methods or different test set-ups can differ significantly from each other. Even measurements preformed on the same test set-up can have a substantial scatter of measured permeability values. This paper discusses the sources of possible measurement errors for a radial flow set-up and their influence on the measured permeability results. Suggestions are given to improve the reliability of permeability measurements.
Effect of Subsequent Aging in SiCP Reinforced AA2124 Aluminum Metal Matrix Composite
Authors: Bozkurt Yahya , Artir Recep , Uzun Hüseyin , Salman Serdar
Published: January 2019

The present study is focused on the evaluation of the aging behaviour and microstructure characterization of AA2124/SiC/25p composite under the aging temperatures of 180, 185 and 190 °C for various dwelling time ranging from 0 up to 100 hours. The microstructure was characterized by means of scanning electron microscopy. The hardness, energy dispersive spectroscopy analysis and X-ray diffraction measurements were also performed to evaluate the characteristics of aged AA2124/SiC/25p composite. The results show that the hardness values of as-received composite were considerably improved up to two third by the subsequent aging. The hardness increasing was attributed to the presence of CuAl2, Al4SiC4 and precipitation phases in aged AA2124/SiC/25p composite.
Optimum Fibre Content for Minimum Weight Monolithic Composite Laminates using Rules of Mixture
Authors: Grove Stephen
Published: January 2019

Using simple rules of mixtures for fibre composite tensile modulus and density, an expression is derived for the optimum fibre content for beams and panels made from monolithic laminates, assuming a minimum stiffness / weight design criterion. Values are considered for a range of typical fibre types, including natural fibres, in the light of practically achievable fibre contents.
The Effect of PP-g-MA/Montmorillonite Ratio on the Rheological Behaviour of Polypropylene/Montmorillonite Nanocomposites
Authors: Chaoui S. , Mehamha A. , Lefebvre J-M. , Miri V. , Seguela R. , Benachour D. , Belkhame N.H. , Cerrada M.L.
Published: January 2019

Nanocomposites polypropylene and modified montmorillonite were prepared by mixture in the melted state using an internal mixer. The effect of the PP-g-MA/Mmt-C18 ratio on the quality of clay dispersion was examined. Results obtained showed that clay is mainly intercalated. The mixture whose PP-g-MA/Mmt-C18 ratio is 3/1 presents the best dispersion of clay. The microstructure and scaling of rheological properties of polypropylene/montmorillonite nanocomoposite have been investigated. The dynamic modulus follows a power law of the type G’ ∼ mps. This evolution show tow zone with different values of the critical exponent s, which can give information about dominant forces in the formed structure.
Elastic Stability Analysis of a Two-Layered Functionally Graded Cylindrical Shell under Axial Compression with the use of Energy Approach
Authors: Sepiani H. , Rastgoo A. , Ahmadi M. , Arani A.Ghorbanpour , Sepanloo K.
Published: January 2019

This paper investigates the elastic axisymmetric buckling of a thin, simply supported functionally graded (FG) cylindrical shell embedded with an elastic layer under axial compression. The analysis is based on energy method and simplified nonlinear strain-displacement relations for axial compression. Material properties of functionally graded cylindrical shell are considered graded in the thickness direction according to a power-law distribution in terms of the volume fractions of the constituents. Using minimum potential energy together with Euler equations, equilibrium equations are obtained. Consequently, stability equation of functionally graded cylindrical shell with an elastic layer is acquired by means of minimum potential energy theory and Trefftz criteria. Another analysis is made using the equivalent properties of FG material. Numerical results for stainless steel-ceramic cylindrical shell and aluminum layer are obtained and critical load curves are analyzed for a cylindrical shell with an elastic layer. A comparison is made to the results in the literature. The results show that the elastic stability of functionally graded cylindrical shell with an elastic layer is dependent on the material composition and FGM index factor, and the shell geometry parameters and it is concluded that the application of an elastic layer increases elastic stability and significantly reduces the weight of cylindrical shells.
Design and Evaluation of an Idealized Porous Medium for Calibration of Permeability Measuring Devices
Authors: Vechart Andrew P. , Masoodi Reza , Pillai Krishna M.
Published: January 2019

Calibration of permeability measuring devices or experimental setups remains an important concern of the flow modeling community of LCM processes (the set of technologies, including RTM and VARTM, that are used for manufacturing polymer composites) since the fidelity of any mold-filling simulation depends on the accuracy of fiber-mat permeability measured through experiments. The design and evaluation of a new cost-effective and accessible calibration-tool for use in both 1-D and radial flow set-ups used in the permeability evaluation experiments is presented here. The tool, comprising of a lattice-like structure patterned out of a repeating unit-cell and based on the design proposed by Morren et al. [ 9 ], represents an idealized porous medium of known permeability that can be used for such calibrations. Stereolithography technique was used to manufacture the tool out of a plastic to fine tolerances. Computational fluid dynamics (CFD) simulations were then performed in the unit cell to evaluate the principle permeabilities of the idealized porous medium. Thereafter, the proposed calibration tool was used in our experimental apparatus to evaluate the accuracy of our permeability measurements. The tool was used for the estimation of accuracy of four different methods: the transient and steady-state tests for the 1-D flow device, and the transient and steady-state tests for the radial flow device. Results show close agreement between the permeabilities estimated through experiments and the permeabilities estimated from the CFD simulation. The study thus establishes the usefulness of the idealized porous medium for calibrating permeability measuring devices.
Vibration and Buckling Analysis of Cylindrical Shells Made of Functionally Graded Materials under Combined Static and Periodic Axial Forces
Authors: Ebrahimi F. , Sepiani H.A.
Published: January 2019

In this study, a formulation for the free vibration and buckling of cylindrical shells made of functionally graded material (FGM) subjected to combined static and periodic axial loadings are presented. The properties are temperature dependent and graded in the thickness direction according to a volume fraction power law distribution. The analysis is based on two different methods of first-order shear deformation theory (FSDT) considering the transverse shear strains and the rotary inertias and the classical shell theory (CST). The results obtained show that the effect of transverse shear and rotary inertias on vibration and buckling of functionally graded cylindrical shells is dependent on the material composition, the temperature environment, the amplitude of static load, the deformation mode, and the shell geometry parameters.
Development of 3D Bioactive Nanocomposite Scaffolds Made from Gelatin and Nano Bioactive Glass for Biomedical Applications
Authors: Mozafari M. , Moztarzadeh F. , Rabiee M. , Azami M. , Nezafati N. , Moztarzadeh Z. , Tahriri M.
Published: January 2019

In this research, macroporous, mechanically competent and bioactive nanocomposite scaffolds have been fabricated from cross-linked gelatine (Gel) and nano bioactive glass (nBG) through layer solvent casting combined with freeze-drying and lamination techniques. This study has developed a new composition to produce a new bioactive nanocomposite which is porous with interconnected microstructure, pore sizes are 200-500 μm, porosity are 72%-86%. Also, we have reported formation of chemical bonds between nBG and Gel for the first time. Finally, the in vitro cytocompatability of the scaffolds was assessed using MTT assay and cell attachment study. Results indicated no sign of toxicity and cells found to be attached to the pore walls offered by the scaffolds. These results suggested that the developed nanocomposite scaffold possess the prerequisites for bone tissue engineering scaffolds and it can be used for tissue engineering applications.
Water Absorption Study on Pultruded E-Glass Fibre Reinforced Unsaturated Polyester Composites
Authors: Akil Hazizan Md , Cheng Leong Wei , Affzan M. H. , Bakar A. Abu , Ishak Z.A. Mohd
Published: January 2019

Glass fibre reinforced unsaturated polyester composites were subjected to water immersion tests in order to study its water absorption behaviour its effects on mechanical properties. Water absorption tests were conducted by immersing composite specimens into three different environmental conditions included distilled water, sea water and acidic solution. Water absorption curves were obtained and diffusion coefficient ( D) and maximum moisture content ( Mm) were determined. The water absorption behaviour of composite was found to follow a so-called Fickian behaviour. The flexural and compression properties were found to decrease with increasing water uptake.
Environmental Effects on Compressive Strength after Impact Loads in Composite Laminates
Authors: Amaro A.M. , Reis P.N.B.
Published: January 2019

The aim of this work is to study the influence of short time water exposition (until 100 h) and temperature in compressive strength of carbon-fibre-reinforced epoxy laminates, before and after low velocity impacts. Specimens were immersed in water at room temperature during 50 h or 100 h, while others were subjected to 80°C during 12 hours, followed by cool down to room temperature. The laminates were manufactured with sixteen unidirectional carbon layers and two stacking sequences [0,90,0,90]2s and [0,90]8. Results show that the temperature influences the compressive strength while the time water exposure studied does not present a significant influence. Pultrusion
Synthesis and Photocatalytic Activity of ZnO/H3PW12O40-Supported Mordenite Composite
Authors: Wang Lingling , Huang Miaoling , Xie Xiaolan
Published: January 2019

12-tungstophosphoric acid (H3PW12O40) and Zinc oxide (ZnO) particles were encapsulated into mordenite by salt melting procedure. The material was characterized by X-ray diffraction (XRD), Ultraviolet-visible diffuse reflectance spectra (UV-Vis-DRS), High Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive Spectrometer (EDS), and Brunauer, Emmett and Teller surface area (BET). The characterization of ZnO/H3PW12O40-supported mordenite composite (ZnO/PW12/mordenite) clearly shows that some of ZnO and H3PW12O40 particles were encapsulated within the cavities and frameworks of mordenite, which effectively increases the photocatalytic activity on degradation of methyl orange. The ZnO/PW12/mordenite composite showed 1.7-fold increase amplitude of the photodegradation rate versus that of ZnO-supported mordenite composite (ZnO/mordenite) without H3PW12O40.
A Study on Ni-Al2O3 Nanocomposite Coating Prepared by Jet Electrodeposition
Authors: Chen Jinsong , Huang Yinhui , Wei Chanzhou , Qiao Bin , Yang Jianming , He Yiqiang
Published: January 2019

Ni-Al2O3 nanocomposite coatings were fabricated by jet electrodeposition process. Effect of concentration of Al2O3 in the electrolyte, current density and electrolyte jet speed on nano-Al2O3 content were analyzed. The composite coatings’ micro structure, energy spectrum was observed under the scanning microscope(SEM). Effect of nano-Al2O3 content on the microhardness and corrosion resistance were evaluated. The results shows that the Ni deposited layers have nanocrystalline micro structure with average size of 50 nm. Al2O3 particles are well dispersed in layer and the particles content is up to 12.2 at %. Microhardness of the coating increase, bond strength and corrosion resistance of the coatings first increase then decrease with increase of Al2O3. content in coatings.
Effect of Boundary Conditions on the Energy Absorption of Composite Tubes
Authors: Huang Jiancheng , Wang Xinwei
Published: January 2019

Composite tubes with different cross-sectional shapes, including quarter circle, half circle and three-quarter circle, are axially crushed to study the boundary effects on the energy absorption of cylindrical shells and develop a semi-empirical analysis method for the crashworthy design of composite structures. It is observed experimentally that all specimens crush from the chamfered end and exhibit stable progressive crushing with similar macroscopic failure modes. Experimental results indicate that the load-displacement curves of all specimens are similar to those of full-circle tubes. And the quarter-circle tubes show the lowest energy absorption capability, while the half-circle tubes and three-quarter-circle tubes show almost the same energy absorption capability. It is found that quarter-circle thermoset tubes without and with one free edge provide 19% and 13% higher energy absorption capability than the quarter-circle thermoset tubes with two free edges; while quarter-circle thermoplastic tubes without and with one free edge provide 6% and 2% higher energy absorption capability than the quarter-circle thermoplastic tubes with two free edges, respectively. It is also found that the semi-empirical analysis method based on crush data and boundary effects of the quarter-circle tubes can accurately predict the energy absorption capability of half-circle or full-circle tubes.
A Novel Manufacturing Technique to Improve Bearing Strength of Pin Loaded Woven Composites
Authors: Sevkat Ercan , Brahimi Malek , Berri Sidi
Published: January 2019

The bearing strength of pin-loaded woven glass-fibre reinforced epoxy composites was investigated. As an alternative to the hole-drilling procedure, a novel composite manufacturing technique has been implemented for pin-hole creation. The bearing performance of composite joints manufactured using both techniques was compared. Specimen with various edge- distances to pin-hole diameter ratios (e/d) and, width to pin-hole diameter ratios (w/d) were tested. It was observed that composite joints manufactured using the novel technique sustained more load compared to the joints manufactured by the hole-drilling procedure. Geometrical parameters were found to be effective on failure modes, bearing strength and magnitude of sustained load.
The Effect of Reinforcement Ratio on the Composite Structure and Mechanical Properties in Al-MgO Composites Produced by the Melt Stirring Method
Authors: Çalin Recep , Muharrem Pul , Çitak Ramazan , Şeker Ulvi
Published: January 2019

In this study, Al- MgO metal matrix composites (MMC) were produced with 5 %, 10 % and 15 % reinforcement- volume (R-V) ratios by the melt stirring method. In the production of composites 99.5 % pure Al was used as the matrix and MgO powders with the particle size of −105 μm were used as the reinforcement. For every R-V ratio; stirring was made at 500 rev/min at 750°C liquid matrix temperature for 4 minutes and the samples were cooled under normal atmosphere. Then hardness and fracture strengths of the samples were determined and their micro structures were evaluated by using Scanning Electron Microscope (SEM). In general, it was observed that the reinforcement exhibited a homogeneous distribution in horizontal direction. But there is a slight inhomogeneity in vertical direction. It was determined that the increase in the R-V ratio increased the porosity and also the hardness. As for the fracture strength, the highest strength was obtained with the 5 % MgO reinforced sample.
Analytical and Finite Element Modelling of Circular Glare Plates under Indentation Loading and Unloading
Authors: Tsamasphyros George J. , Bikakis George S.
Published: January 2019

In this paper, analytical expressions are derived and a finite element modelling procedure is proposed in order to predict the static load-indentation curves of circular GLARE fibre-metal laminates during loading and unloading by a hemispherical indentor. Analytical formulas have been recently published for the static indentation of circular GLARE plates which are now used during the loading stage. Here, considering that aluminum layers are in a state of membrane yield and employing energy balance during unloading, the unloading path is determined. Using this unloading path, an algebraic equation is derived and solved for calculating the permanent dent depth of the GLARE plate after the indentor's withdrawal. ANSYS software is used and a non-linear analysis is employed with geometric and material non-linearities for FEM calculations. The derived formulas and the proposed finite element modelling procedure are applied to GLARE 2-2/1-0.3 and to GLARE 3-3/2-0.4 circular plates. The analytical results are compared with corresponding FEM results and a good agreement is found. The analytically calculated permanent dent depth is within 6 % for the GLARE 2 plate, and within 7 % for the GLARE 3 plate, of the corresponding numerically calculated result. No other solution of this problem is known to the authors.
Investigation of Unlubricated Sliding Wear Behaviours of In-Situ AlB2/Al Metal Matrix Composite
Authors: Ficici Ferit , Koksal Sakip , Kayikci Ramazan , Savas Omer
Published: January 2019

In this study, wear behaviour of AlB2/Al composite materials produced through in-situ method have been experimentally investigated. Four different composite materials that include 5wt.%, 10wt.%, 20wt.% and 30wt.% AlB2 reinforcement phase were tested using pin-on-disk arrangement. The effects of the rate of reinforcement on wear and friction behaviours have been investigated. Wear tests are carried out at 1.83, 3.40 and 4.71 m/s sliding speeds under 10, 20 and 40 N applied loads. The test results show that wear rate increases with the increase in applied load and sliding distance. Increasing the rate of reinforcement phase in the matrix has proportionally increased the wear resistance by 3% to 30%. Hence the greatest wear resistance has been observed with the composite materials having 30wt. % AlB2 reinforcement. Analysis of the worn surfaces of composite samples shows that abrasive and adhesive wear mechanisms are more effective.
Sensitivity Analysis for the Spring-in of Composite Shells
Authors: Dong Chensong
Published: January 2019

Composite materials are a class of engineering materials widely used in a wide range of industries. Spring-in is a common dimensional variation of composite shells. It is well known that spring-in is dependent on many factors e.g. the constituent properties and coefficients of thermal expansion (CTE). A sensitivity analysis on the spring-in is presented in this paper. The sensitivities of the spring-in to the constituent properties and CTE are studied by the Design of Experiments (DOE) and the Response Surface Method (RSM). It is shown that the spring-in is predominantly sensitive to the Poisson's ratio of the matrix and the transverse CTE of the fibres. The results can be used to estimate the uncertainty of the spring-in from the uncertainties of the constituent properties and CTE, which is potentially useful for the design of composite products with improved dimensional control.
State of the Art on Permeability Characterization of Fibrous Reinforcements used in Resin Transfer Molding Process
Authors: Patiño I.D. , Vanegas J.D. , Correa C.E.
Published: January 2019

The physical and mathematical fundamentals that are required for the measurement of permeability of fibrous reinforcement used in Resin Transfer Molding (RTM) and to interpret correctly the results of those experiments are considered in this article. The basic concepts of fluid dynamics through porous media applied to the analysis of the impregnation phenomena in fibre preforms are discussed. The principal assumptions to simplify the governing equations into the Darcy's law are summarized in order to give an idea of some typical features of the permeability tests regarding the injection parameters and types of fluids and preforms used. Three important concepts for determining permeability in any direction for anisotropic preforms are introduced: permeability tensor ( Kij), permeability ellipse and effective permeability ( Keff). This paper also deals with the deduction, from Darcy's law and Laplace Equation, of the basic equations used on the unidirectional and divergent radial permeability tests. The final conclusion remarks the importance of the concepts exposed in this work.
Application of Taguchi Method to Investigate the Effect of Some Factors on In-Situ Formed Flake Structures of AL/ALB2 Composite
Authors: Savaş Ö. , Kayikci R. , Köksal S.
Published: January 2019

A new in-situ metal matrix composite has been produced by liquid state reaction between aluminium and boron. The common boride phases obtained from this reaction are AlB12 and AlB2 of which the latter is stable at room temperature. One of the critical parameters of the reinforcement is the aspect ratio of AlB2 flakes. In this study, the Taguchi design method has been employed to examine the effects of three process parameters of additive elements to Al matrix, cooling rate in the AlB12(solid) + Al(liquid) region, and cooling regime in the AlB2(solid) + Al(liquid) region on the size of AlB2 flakes. In the experiments, melting, casting, solidification, metallographic techniques, optical microscope, SEM and wet analysis techniques have been used. Results showed that 1.3 wt % boron has been dissolved in the aluminium at 1400 °C by adding boron oxide (B2O3) resulting in AlB2 flakes of 2.5 % by volume. It is also concluded that the AlB12(solid) + Al(liquid) region has to be passed with adequately high cooling rates in order to obtain AlB2 flakes with highest possible aspect ratios.
Fatigue and Thermal Failure of Polymeric Composites Subjected to Cyclic Loading
Authors: Katunin Andrzej , Fidali Marek
Published: January 2019

In the presented study the experimental results for the investigation of fatigue of polymeric composites subjected to intensive cyclic loading with presence of the self-heating effect were presented. Experiments were carried out on laboratory stand, which provides the synchronous measurement of loading force, displacements and temperature. It was observed, that the fatigue process during occurrence of the self-heating effect consists of three phases, which were analyzed and described. The characteristic self-heating temperature distributions and their evolution during the whole loading history were analyzed. The parametric analysis of influence of loading conditions on the self-heating temperature evolution and fatigue of polymeric composites was presented. Basing upon the measurement results the authors proposed empirical models, which give a qualitative evaluation of parametric dependencies.
Wear Properties and Microstructures of the Laser Synthese Ceramics Reinforced Composite Coatings on Titanium
Authors: Liu Peng , Zhang Yuanbin , Luo Hui , Huo Yushuang
Published: January 2019

In this study, the Al/Mg powders were firstly used to improve the wear resistance of titanium by mean of the laser cladding technique, which owned a great potential in the field of the surface modifications of the metals. Laser cladding of the Mg/Al+TiN pre-placed powders on pure Ti can form the TiN reinforced composite coatings. With addition of 10wt.%TiC, the growth of the TiN was retarded in a certain extent, which further increased the wear resistance of the coating. This research provided essential experimental and theoretical basis to promote the application of the laser cladding technique in the manufacturing and repairing of the aerospace parts.
Development of Empirical Relations for the Transversely Isotropic Properties of Zigzag, Armchair and Chiral Single-Walled Carbon Nanotubes
Authors: Jalan S.K. , Rao B. Nageswara , Gopalakrishnan S.
Published: January 2019

Finite element analysis has been performed to evaluate transversely isotropic properties of the single walled carbon nanotubes (SWCNTs). Finite element models of SWCNTs are generated by specifying the C-C bond rigidities (which are arrived by equating the energies from molecular mechanics and continuum mechanics). The five independent transversely isotropic properties for different chiralities are evaluated using the stress fields of thick-walled cylinders and the elastic deformations of SWCNTs subjected to pure extension, internal pressure and pure torsion loads. The adequacy of the elastic properties is demonstrated through modelling of an equivalent overall orthotropic hollow thick-walled cylinder under different loading conditions. Empirical relations are provided for the five independent elastic constants useful for armchair, zigzag and chiral zigzag SWCNTs.
Optimization of Wedm Parameters on Machining of Al7075 Based Hybrid MMCs
Authors: Satishkumar D. , Kanthababu M. , Saravanan R. , Moorthy T. , Saravanan P. , Srinivasan G.
Published: January 2019

This investigation is aimed towards the optimization of wire electrical discharge machining (WEDM) parameters of the hybrid MMCs consisting of aluminium alloy (Al7075) reinforced with boron carbide (B4C) and alumina (Al2O3) particles at four distinct volume fractions. The effect of important WEDM parameters such as pulse-on (TON), pulse-off (TOFF), gap voltage (V) and wire feed (F) on material removal rate (MRR) and surface roughness (Ra) are studied. The experiments are carried out as per L9 orthogonal array (OA) using design of experiments (DOE) approach. Analysis of variance (ANOVA) is used to identify significant parameters for achieving higher MRR and lower Ra. From the study, it is observed that increase in percentage volume fraction of the reinforcements resulted with decrease in MRR but increase in the Ra value. Regression equations are presented to represent the relationship between input and output parameters.
Impactor Shape Effect on Low Velocity Impact Response of Woven Glass Epoxy Composites
Authors: Icten Bulent Murat , Kıral Binnur Gören
Published: January 2019

This study deals with the effect of impactor shape on the impact response of plain woven glass-epoxy laminates. Impact tests were performed by using Fractovis Plus test machine with seven different impactor noses grouped as hemispherical, conical and flat. Specimens were impacted at low (5 J) to high energy levels (45 J) enough to obtain perforation of the composite at the room temperature. Variation of the impact characteristics such as maximum contact load, maximum deflection, total contact time and absorbed energy versus impact energy are depicted in Figs. Results indicated that the projectile shape highly affects the impact response of composite materials.
Effect of Washer Type on Bearing Strength of Bolted-Joint Laminated Composites
Authors: Arman Yusuf
Published: January 2019

There are various parameters for bolted joints used in so many industries. The main objective of this work was to investigate the influence of washer type as a bolting parameter on the bearing strength of bolted joints in laminated composites. Therefore, by using three different washer types; flat washer, spring washer and tooth lock washer, an experimental study was performed. Quasi-isotropic glass-fibre reinforced epoxy laminated composites were used in the study. Four different tightening torques ( T = 2, 3, 4, 5 Nm) were chosen for the bolted joints in the experiments, for each washer type. E/W ratio was chosen as 0.25, 0.5, 0.75 and 1 in order to investigate damage modes of composite samples. It was applied tensile test, through a centroidal axis, on each specimen. From these tests, load-displacement curves of the specimens were drawn. The maximum failure loads and bearing strengths of the bolted joints were obtained from the load-displacement curves. From the experimental results, it is noted that bearing strength of the specimens with flat washer is higher than the specimens with tooth lock and spring washer, respectively. Also, it is concluded that higher tightening torque increases the bearing strength, and E/W ratio should be determined as larger than 0.25 for a damage tolerant design in terms of bearing strength.
Preparation of Poly (Methacrylic Acid-Ethanolamine Modified Maleic Anhydride)/Montmorillonite Nano-Composite Using Initiator-Montmorillonite Hybrid
Authors: Bao Yan , Jianzhong Ma , Tao E.
Published: January 2019

2,2′-Azobis (2-methylpropionamidine) dihydrochloride-montmorillonite (AIBA-MMT) hybrid was prepared by cationic exchange between the Na+ ion in the MMT galleries and the quaternary ammonium of the azo-initiator. Then the methacrylic acid-ethanolamine modified maleic anhydride copolymer/montmorillonite [P(MAA-EMA)/MMT] nano-composite was prepared via in-situ polymerization method using above AIBA-MMT hybrid. The structures of AIBA-MMT hybrid and P(MAA-EMA)/MMT nano-composite were characterized with X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The interlayer d-spacing of AIBA-MMT was 1.50 nm. The amount of the initiator intercalated into the clay galleries was 0.508g/gMMT. The P(MAA-EMA)/MMT nano-composite was categorized as exfoliated and intercalated one. The application results of P(MAA-EMA)/MMT nano-composite for leather tanning indicated that nano-composite can improve the wet-heat resistance temperature of collagen and facilitate the absorption of chromate.
Composite Foams Prepared through Hollow Glass Microspheres Assisted Bubbling
Authors: An Zhenguo , Zhang Jingjie
Published: January 2019

Composite foamy structures were prepared through hollow glass microspheres (HGM) assisted bubbling of silicone rubber with ammonium hydrogen carbonate as the blowing agent. The presence of HGM not only favoured the foaming process (acted as nucleating agent for the formation of minute bubbles at the initial stage of the bubbling), but also bring heterogeneous close-cell bubbles with stable inorganic shells into the foamy structure, which played an important part in the improvement of the heat insulation property of the product. Compared to the foamy structures without HGM, The composite foamy structures possessed improved heat insulation and sound absorbing properties. This work provides an additional strategy to fabricate composite foams with tailored cell structure and properties.