bluuebunny/crossref_metadata_2025 huggingface dataset:
Design Buckling Curves for Clamped Orthotropic Laminated Plates
Authors: Tsouvalis Nicholas G. , Papazoglou Vassilios J.
Published: January 2019

Non-dimensional design buckling curves for clamped rectangular orthotropic plates are presented in this study. These curves provide the critical buckling load of thin, symmetric, cross-ply laminated plates as a function of the laminate's rigidities and aspect ratio for the following seven configurations of the applied in-plane loads: uniform uniaxial compression, triangular uniaxial compression, uniaxial in-plane bending, pure shear, uniform uniaxial compression combined with shear, triangular uniaxial compression combined with shear, and uniaxial in-plane bending combined with shear. Approximate mathematical formulae are also provided. The Classical Lamination Theory, in conjunction with the Rayleigh-Ritz method, has been used for the determination of the critical buckling load. The validity of the study is confirmed by comparing its results with other both theoretical and numerical ones.
A Study on the Measurement Technique of Resin Flow and Cure during the Vacuum Assisted Resin Transfer Moulding Process using the Long Period Fibre Bragg Grating Sensor
Authors: Yoon Youngki , Chung Seunghwan , Lee Woo Il , Lee Byoungho
Published: January 2019

Long Period Gratings (LPGs) are currently being used in various fibre-optic sensor implementations. In this study, Long Period Fibre Bragg Grating was applied to monitor the resin flow and the curing process in the Vacuum Assisted Resin Transfer Moulding (VARTM) process. The principle of measurement is explained. In order to demonstrate the effectiveness of the method, gratings are inserted into the glass mat to monitor the resin flow during VARTM process. Signal from the sensor is processed by an optical spectrum analyzer (OSA). The curing reaction is also monitored using the same method. From the results, it is shown that the proposed LPGs sensor is effective in monitoring the resin flow as well as the curing reaction during VARTM process.
Modelling of Moisture Sorption by Cfrp Rebars with Vinylester Matrix
Authors: Starkova Olesja , Aniskevich Andrey
Published: January 2019

The results of experimental investigation and modelling of moisture sorption by CFRP rebars and vinylester matrix are presented. Experimental values of the rebar diffusion coefficients essentially differ from those predicted using structural approach. Essential anisotropy of sorption process in longitudinal and transverse directions is observed. Quasi three phase model is suggested for description of the CFRP rebar sorption. The model is based on consideration of sorption process of the diffusion character in the composite consisted of two phases: resin and microplastic, which includes fibres and fibre-resin interphase. The suggested model describes the experimental sorption data quite satisfactorily and explains high anisotropy effect.
Effects of Piezoceramic Particle Addition on the Fracture Toughness Behaviour of CF/EP – Composites
Authors: Rosso Patrick , Tanimoto T. , Friedrich Klaus
Published: January 2019

In this study, the influence of piezoelectric ceramic particles (PZT) on a continuous carbon fibre (CF) reinforced epoxy was investigated. Therefore, unidirectional laminates were produced via film stacking in an autoclave. Mode-I interlaminar fracture toughness tests were carried out as well as tensile tests and short beam shear test to evaluate E-modulus and interlaminar shear strength (ILSS), respectively. The amount of PZT was varied and additional fracture surface analysis by scanning electron microscopy (SEM) clarified how the PZT affects the GIC of the particular laminates. It was found, that the addition of the PZT-particles caused a significant decrease in fracture toughness, whereas stiffness and ILSS were effected only marginally.
A Novel Adaptive Process Control for Injection Moulding of BMC and CIC Polyester Compounds
Authors: Lafranche Eric , Cilleruelo Laura , Ryckebusch Marc , Krawczak Patricia
Published: January 2019

The formulation of unsaturated polyester Bulk Moulding Compounds (BMC) or Continuously Impregnated Compounds (CIC) induces a variation of their reactivity or viscosity, which reflects the heterogeneity of the material batches produced. This experimental study has pointed out the benefits brought by an advanced process control of the injection moulding holding stage (feedback control on the polymer pressure in the mould cavity with automatic set up of holding time) compared to a regular process control (feedback control on the hydraulic pressure). The advanced process control actually leads to the reduction of the scattering observed on bulk (weight, specific gravity), surface (porosity, roughness) or mechanical properties (Charpy impact strength). It allows smoothing the thermal perturbations induced by a manufacturing start-up, as well as the rheological perturbation due to the material batches heterogeneity that are frequently encountered in the unsaturated polyester compound injection moulding industry. This scattering decrease, centred on the mean value of the target properties, directly involves significant quality and productivity improvement.
Fibre Orientation Effects on High Strain Rate of Carbon/Epoxy Composites
Authors: Ferrero J. F. , Tawk I. , Rivallant S. , Barrau J. J. , Sudre M.
Published: January 2019

Specific mechanical properties of composites make them particularly attractive. Dynamic loads are of prime interest for their applications. Laminated structures’ impact modelling implies prior material dynamic characterisation. This study suggests an analysis of split Hopkinson bar compression testing on T300/914 carbon/epoxy composite material. First, the effect of fibre orientation and stratification on compression dynamic behaviour is studied. Results show a high non-linearity for +/-45° laminates testing. This non-linearity is not observed when the laminates are reinforced with 0° and 90° plies. Analytical modelling is in agreement with the experimental results. Secondly, experiments are performed on pre-cracked specimens to show the influence of cracking on dynamic behaviour.
Elastic-Plastic Thermal Stresses in a Composite Disc with Multiple Holes
Authors: Sen Faruk
Published: January 2019

The goal of this study was to investigate elastic-plastic thermal stresses in a thermoplastic composite hollow disc with multiple holes. Different uniform temperature distributions were subjected to the disc as thermal loadings. The thermoplastic composite disc was reinforced by steel fibres as unidirectional for radial direction. Finite element method (FEM) was used to calculate both thermal and residual stresses. Therefore, the thermal stress analysis was carried out using ANSYS finite element software which is known a general purpose engineering simulation. Due to the composite disc having different thermal expansions in radial and tangential directions, thermal stresses were created in it by the applied thermal loadings. The magnitude of the tangential stress components both elastic and elastic-plastic solutions was higher than the radial stress components except edges of multiple holes. In addition, the residual stress components were computed using elastic and elastic-plastic solution results. The calculated results pointed out that the magnitude of thermal and residual stresses were considerably affected increasing of uniform temperature loadings.
Draping of Textile Composite Reinforcements: Continuous and Discrete Approaches
Authors: Boisse P. , Hamila N. , Helenon F. , Aimene Y. , Mabrouki T.
Published: January 2019

The textile reinforcements used for composites are multiscale materials. A fabric is made of woven yarns themselves composed of thousand of juxtaposed fibres. For the simulation of the draping of these textile reinforcements several families of approaches can be distinguished in function of the level of the modelling. The continuous approaches consider the fabric as a continuum with a specific behaviour. The discrete approaches use models of some components such as the yarns and sometimes the fibres. Different approaches used for the simulation of woven reinforcement forming are investigated in the present paper. Among them, an approach based on semi discrete finite elements made of woven unit cells under biaxial tension and in-plane shear is detailed. The advantage and inconvenient of the different approaches are compared.
Analysis of Load Transfer Behaviour and Determination of Interfacial Shear Strength in Single-Fibre-Reinforced Titanium Alloys
Authors: Matikas Theodore E.
Published: January 2019

The effect of interfaces on load sharing behaviour has been evaluated by performing single-fibre fragmentation (SFF) experiments and analysis of titanium matrix composites at ambient and elevated temperatures. Fibre breaks were monitored by acoustic emission sensors, and the break locations were determined in-situ by an innovative ultrasonic non-destructive evaluation technique. Data analysis of SFF testing was performed using the Kelly-Tyson model. The length of fibre fragments and distribution were determined using innovative nondestructive technique. This study demonstrates that composite processing conditions can significantly affect the nature of the fibre/matrix interface and the resulting fragmentation behaviour of the fibre. Further, thermal micro-residual stresses, generated during the fabrication process and in-service due to the difference in thermomechanical characteristics of the model composite's constituents, play a major role influencing the interfacial shear stress transfer behaviour in single-fibre titanium matrix composites.
Characterization of Interphase Environmental Degradation at Elevated Temperature of Fibre-Reinforced Titanium Matrix Composites
Authors: Matikas Theodore E.
Published: January 2019

Fibre reinforced metallic composite materials are being considered for a number of applications because of their attractive mechanical properties as compared to monolithic metallic alloys. An engineered interphase, including the bond strength between the composite's constituents, contributes to a large extent to the improvement of strength and stiffness properties of this class of materials. However, in high temperature applications, where combination of cyclic loading with environmental effects is expected, consideration should be given to interphase degradation, especially in the vicinity of stress risers, such as notches and holes. The applicability of damage tolerance analysis in structural components made of titanium matrix composite materials designed to operate under high temperature environments would depend on the availability of adequate characterization methods for the evaluation of interfacial degradation.

The objective of this paper is to provide a basic understanding of interfacial degradation mechanisms due to oxidation in environmentally exposed titanium-based composites subjected to cyclic stresses. A non-destructive method has been developed enabling high-resolution monitoring of interfacial damage initiation and accumulation as well as surface/subsurface cracking behaviour during interrupted fatigue tests. This nondestructive technique is based on surface acoustic wave propagation in the composites and can detect minute changes in elastic properties of the interfacial region due to elevated temperatures as well as oxygen effects.
Influence of Phenolic Resin Surface Treatment Agent on Interfacial Adhesion of Carbon Fibre Reinforced Epoxy Resin Composites
Authors: Wang Chao , Wang Jing , Niu Yongan
Published: January 2019

To enhance the interfacial adhesion between carbon fibre and epoxy resin matrix, phenolic resin surface treatment agent has been carried out. The influence of phenolic resin treatment agent on interfacial adhesion of carbon fibre reinforced epoxy resin composites were investigated by interlaminar shear strength, atomic force microscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The results indicated that the interfacial adhesion was improved greatly after carbon fibre treated by phenolic resin surface treatment agent.
Stress Analysis of Filament-Wound Composite Cylinders under Combined Internal Pressure and Thermal Loading
Authors: Çallıoğlu Hasan , Ergun Emin , Demirdağ Oktay
Published: January 2019

An analytical solution is performed using stress function approach for multi-layered filament-wound composite cylinders subjected to combined internal pressure and thermal loading. It is assumed that there is a liquid or gas of various temperatures in the cylinders. The effects of the wind angle variation through the radial section of the cylinders are also investigated. Thus, the layers are oriented symmetrically and antisymmetrically for (0°/90°), (30°/-30°), (45°/-45°) and (60°/-60°) orientations. A computer program is developed to conduct stress and deformation analyses of composite cylinder with different winding angle. All the integration constants are found from the radial stress and displacement in the normal direction of layers.
Defect Controlled Water Jet Piercing of Continuous Fiber Reinforced Plastics
Authors: Machida T. , Ramkumar J.
Published: January 2019

Water jet piercing of composite laminates finds a wide application in varying fields of manufacturing, but has an inherent problem of delamination which restricts its usage. This paper makes an attempt to successfully make smaller diameter holes using impulse water jet. Both experimental and theoretical results confirmed that while piercing of composite laminates using water jet the defects appear in between the layers of laminates which may be due to bending moment of the bottom plies, which is because of the high pressure jet involved in piercing process. As the hole progresses the bottom layer delaminates from the previous layers which can be analogized to a simple supported beam in the initially stages and finally this gets converted into a cantilever beam at the bore edges. These defects can be effectively prevented by supporting the work material behind the cut edges with a thick plate having a bore smaller than that of the nozzle.
Mechanical Properties of 2D C/SIC Composites with Two Different Carbon Tows
Authors: Wang Yiqiang , Zhang Litong , Cheng Laifei , Ma Junqiang
Published: January 2019

The mechanical properties of woven cloth with two sizes of carbon tows reinforced silicon carbide composites were investigated by tension, shear and bending tests. The experimental results show that the composite fabricated with small tows possesses greater stiffness and strength than the composite with large tows. Unequal tow size caused differences of the warp waviness and the void volume fraction in the composites, which led to differences in mechanical properties of composites.
Preparation and Mechanical Properties of Fe3Al-MWNTs Composites
Authors: Pang Laixue , Zhang Jinsheng , Xu Jing
Published: January 2019

Multiwall carbon nanotubes (MWNT) reinforced iron aluminides (Fe3Al) intermetallic matrix composites have been prepared by a conventional (hot pressing) sintering method. Morphological, structural, compositional and mechanical properties investigations have been performed. Compressive testing shows that the composites still display high yield strength. The first results show that carbon nanotubes have been preserved in composite structure during the sintering process.
Thermal Stability of Polypropylene/Organo-Clay Nanocomposites Produced in a Single-Step Mixing Procedure
Authors: Bogoeva-Gaceva Gordana , Raka Luljeta , Dimzoski Bojan
Published: January 2019

Thermal stability of polymer nanocomposites prepared by melt mixing of polypropylene (PP) with organo-modified clay (Cloisite C93A) and maleic anhydride grafted polypropylene (PP-g-MA) used as compatibilizer, has been studied. Thermogravimetric analysis (TGA/DTG) results showed improved thermal stability of PP in the presence of organo-clay in oxygen atmosphere. Significant prolongation of oxidation induction time (measured at 200°C) for nanocomposite, in the presence of even 1% organo-modified clay has been found.
Failure Analysis of Woven Glass- Epoxy Prepreg Bolted Joints under Different Clamping Moments
Authors: Esendemi̇r Ümran
Published: January 2019

In this study, an experimental investigation was carried out, in order to study pin- bearing strength, failure modes under various clamping moments depending on the geometrical parameters. Two different geometrical parameters were investigated. For that reason, the ratio of the distance from the pin centre to the top edge top in diameter (E/D), and the ratio of the specimen width to the pin diameter (W/D) were suitably varied, in order to verify their influence on the failure modes consisting of net-tension, cleavage and bearing. Totally, 160 specimens were tested. The mechanical properties of prepreg composite were obtained from standard tests. Experimental results showed that failure modes and bearing strengths were strictly influenced from increasing value of applied clamping moments and geometrical parameters.
Strengthening of RC T-Section Beams Subjected to Cyclic Load Using CFRP Sheets
Authors: Sakar Gokhan , Alku Omer Zafer
Published: January 2019

The results of an experimental and analytical study of the behaviour of reinforced concrete (RC) T-section beams strengthened with carbon fibre reinforced polymer (CFRP) sheets are presented. Shear deficient specimens are strengthened by using side-bonded and [Formula: see text] - jacketed CFRP sheets. The effect of CFRP sheets on strength and stiffness of the beams is considered for various orientations of the fibres. The main objective of the study is to obtain ductile flexural behaviour from the shear deficient RC beams. To verify the reliability, test results were compared with results of ACI-440 design code, Concrete Society TR55, Fib Bulletin 14 and Colotti et al. model.
Physical Properties of Short Pineapple Leaf Fibre (PALF) Reinforced High Impact Polystyrene (HIPS) Composites
Authors: Siregar J. P. , Sapuan S. M. , Rahman Ab. , Zaki M. , Zaman H. M. D. Khairul
Published: January 2019

The aim of this study to investigate the physical properties of short pineapple leaf fibre (SPALF) reinforced high impact polystyrene (HIPS) composites. Three different sizes of the fibre were used in this study which was 10-40mesh, 40-60mesh and 60-80mesh. A five different fibre contents were used in this study which was 10%, 20%, 30%, 40%, and 50%. The fabricated SPALF/HIPS composites were used melt mixing and compression moulding. The physical properties of SPALF/HIPS composites such as water absorption, thickness swelling, melt flow index (MFI), and density board of composites were studied. The result showed that the addition of the SPALF was decreased the physical properties compare to pure HIPS (0% SPALF).
Free Vibration and Buckling Analysis of the Laminated Composite Beams by Using GDQM
Authors: Atlıhan Gökmen , Demir Ersin , Girgin Zekeriya , Çallıoğlu Hasan
Published: January 2019

In this study, effects of stacking sequences of composite laminated beams on natural frequencies and buckling behaviour have been analyzed by Generalized Differential Quadrature Method (GDQM) and Finite Element Method (FEM). Mode shapes were also investigated for one mode of buckling and three modes of free vibration analyses. In addition, variations of mode shapes for different boundary conditions were presented in details. Numerical results show that the effective stiffness of the laminated composite beam can be altered through an adjustment in the stacking sequence. Thus, such an adjustment in stacking sequences allows operations in desired natural frequencies and load carrying capacity without changing its geometry drastically or without changing its weight.
Analysis of Sandwich T-Joints under Compression Loads in Marine Applications
Authors: Özes Çiçek , Aydin Özgen
Published: January 2019

This paper deals with the analysis of sandwich T-joints in terms of buckling loads, which are used in marine applications. Buckling loads have been investigated experimentally and numerically. Loading is applied as uniform axial compression. The GRP/PVC sandwich composite T- joints have been manufactured in six different geometries. Numerical and experimental results both show that the geometry of the T-joint area affects the buckling loads. It has been observed that failure mode is the same in all of the joint types, which is core shear. Stress distributions in T-joints have also been investigated under buckling loads and also for a constant compression load. It is seen that T-joint geometry has an effect on stress distributions obtained under buckling loads.
Buckling Behaviour of Carbon/Epoxy Laminated Composite Plates under Biaxial Loading
Authors: Aktaş Mehmet
Published: January 2019

In this numerical and analytical study; the length-to-thickness ratio (a/t), aspect ratio (a/b), Young modulus ratio ( E1/ E2), load ratio ( Nx/ Ny) and different boundary conditions effect on buckling behaviour of carbon/epoxy composite laminated plate were investigated. The composite plate was assumed four plies as [θ°]4. The fibre orientation, θ, was chosen as 0°, 15°, 30°, 45°, 60°, 75° and 90°. The Veres-Kollar approach [ 1 ] was used to calculate the buckling load, analytically. Also, ANSYS 10 commercial software was used for determination of buckling load, numerically. The plate has simple supported boundary condition at four edges during analytical and numerical study. Good agreements between analytical and numerical results were obtained. Results showed that the buckling load changes depend on the dimension and material properties of the plate, boundary conditions and loading cases.
Effect of Processing and Loading Conditions upon the Fatigue Behaviour of a Cf/Epoxy Laminate
Authors: Koimtzoglou Christos , Dassios Konstantinos G. , Galiotis Costas
Published: January 2019

The current work reports on the tensile and fatigue behaviour of an autoclave-cured unidirectional carbon fibre reinforced epoxy-matrix laminate. The macromechanical properties of the composite are established under interrupted and uninterrupted, static and dynamic conditions at a maximum strain below the critical fatigue limit of the matrix material. The established S-N curve was used to calculate the endurance fatigue limit of the laminate as well as to record an increase in fatigue life of specimens tested at load levels lower than two standard deviations below the mean static strength of the material. The failure modes exhibited by the composite under all testing conditions were recorded and interpreted by means of the damage mechanisms that originate them. The results of interrupted testing showed that the combined effect of fatigue and residence at high stress levels for prolonged periods of time - conditions that simulate a realistic loading scheme- trigger premature fibre failure and thus specimen failure.
Comparative Study between PP-g-MAH and PP-methyl-POSS as Compatibilizer for NanoSiO2/PP Composites: Mechanical and Morphological Properties
Authors: Lin Ong Hui , Akil Hazizan Md , Ishak Z. A. M.
Published: January 2019

The work presented in this paper discussed the effect of two types of compatibilizer such as polypropylene grafted maleic anhydrate (PP-g-MAH) and polypropylene methyl polyhedral oligomeric silsesquioxane (PP-methyl-POSS) in nanosilica/polypropylene (nanoSiO2/PP) composites on the mechanical behaviour. Nano-SiO2/PP composites, containing 1, 2, 3, 4 and 5 wt% of fumed silica nanoparticles were prepared using a thermo Haake internal mixer with addition of 1 wt% compatibilizer according to the total composite weight. The purposed of using the compatibilizer was to reduce the size of particles agglomerates and improve filler dispersion in the polymeric matrix. The composites were characterized by tensile and impact testing as well as SEM studies. This study clearly demonstrated that the addition of compatibilizer into the composite systems modifies the mechanical properties. Results of the mechanical properties indicate that due to its characteristic, each compatibilizer gives rise to increase particular mechanical properties. At low filler concentration, PP-methyl-POSS showed better stiffness in the nanoSiO2/PP composites. While, the addition of PP-g-MAH provided better tensile and impact properties compared to PP-methyl-POSS in the rage of filler content in this study.
Sliding Wear Behaviour of an Epoxy System Reinforced with Particulate fly Ash Filler
Authors: Barpanda P. , Kulkarni S.M. , Kishore
Published: January 2019

Neat epoxy and epoxy containing different volume fraction of as received fly ash particulate filler bearing composites were cast, sectioned and subjected to pin-on-disk tests for evaluating the wear behaviour. The wear tests were conducted for 1 kilometre distance under 1 kg load for sliding velocity ranging from 1 to 5 m/s. The results showed that both neat epoxy and fly ash bearing composites exhibit differing magnitudes of wear loss, it being highest for unreinforced neat epoxy system. The data trends point to the fact that wears loss decreases with increasing content of fly ash in composites. To explain these differences, the wear surfaces were examined under scanning electron microscope and the features thus observed were correlated with the mechanical data.
An Experimental Study on the Scratch Characteristics of Bamboo Fibre-Reinforced Epoxy Composite
Authors: Low K. O. , Lim J. L. , Wong K. J.
Published: January 2019

Bamboo fibre has been used as reinforcement in epoxy. The influence of bamboo fibres orientation on the scratch characteristics has been studied by single pass scratching action and evaluated in terms of scratch force and scratch hardness. The composites are prepared for three different fibre orientations, longitudinal, transverse and 10 mm random. Five values of applied load (2 N, 5 N, 10 N, 12 N, 15 N) and two scratching speeds (5.6 mm s−1, 11.2 mm s−1) are considered. The results revealed that the introduction of bamboo fibres tends to increase the scratch force for all composites considered except for longitudinal orientated fibre composite. The scratch hardness shows improvement when bamboo fibre is introduced, except for the longitudinal case. The best result for scratch hardness is exhibited by transversely orientated bamboo fibre reinforced epoxy corresponding to 35 % improvement.
The Effect of Stacking Sequence and Temperature on the Mechanical and Low Velocity Impact Response of Glass/Epoxy Laminates
Authors: Benli Semih , Sayman Onur , Arman Yusuf
Published: January 2019

This paper demonstrates both low velocity impact and mechanical test results of glass/epoxy composites at room and high temperatures. Square specimens of glass/epoxy composite laminates with lay-ups [0/0/90]s, [90/0/0]s, [0/90/45]s were subjected to low velocity impact energy range of 4 J to 22 J using an impact test machine at temperatures of 20°C, 50°C and 90°C. Load-deflection and energy profile diagrams were plotted for each stacking sequence and temperature. After impact, a high-intensity light was used to measure the projected delamination areas in the impacted glass/epoxy composite laminates. In order to investigate effects of temperature on mechanical properties and impact resistance, mechanical tests were also performed using unidirectional glass/epoxy composite plates composed of eight plies produced according to ASTM Standards. In addition, to understand the contribution of thermal residual stresses occurring during and after manufacturing of composite laminates on impact-induced delamination, SX and SY stresses in the composite laminates at 20, 50 and 90°C were determined by using ANSYS software. It can be concluded from this study that temperature has significant effects on the impact behaviour and mechanical properties of glass fibre-reinforced epoxy composite laminates. Besides, an increase in temperature decreases both the delamination area and the contribution of thermal residual stresses on delamination under the same impact loading.
The Effect of CaSiO3 Nano-Particles Reinforced Denture Polymethyl Methacrylate
Authors: Qian Chen , Zhang Xiu-Yin , Zhu Bang-Shang , Lin Kai-Li , Chang Jiang , Zhang Xin-Jing
Published: January 2019

The preparation of CaSiO3–PMMA nanocomposite denture matrix was reported. We investigated the optimal amount of CaSiO3 nano-particles modified by silane coupling agent (Z-6030) on strengthen flexural strength and surface hardness (Knoop hardness) of the nano-CaSiO3/PMMA composite materials. The results indicated that the 1.5% CaSiO3 nano-particles could enable the nanocomposite to have the maximum flexural strength (90.50±4.86) MPa(increasing nearly 40% contrast to the blank group), while 2.0% CaSiO3 nano-particles made the nanocomposite to have a maximum Knoop hardness(24.59±0.98) MPa (augmenting with 24% compared with the blank group). Furthermore, the fracture surface was investigated by scanning electron microscope (SEM), which revealed that the silane coupling agent (Z-6030) affected the dispersion of the CaSiO3 nano-particles in PMMA matrix, and the fracture surface of the 1.5% group is regular with obvious ductile dimple pattern demonstrating typical ductile fracture.
Physical and Mechanical Properties of Rigid Polyurethane Faoms Modified with Selected Flame Retardants or Layered Silicates
Authors: Piszczyk Łukasz , Danowska Magdalena , Strankowski Michał , Gibas Iwona , Haponiuk Józef Tadeusz
Published: January 2019

The flame retardants: expandable graphite, decabromodiphenyloxid, triethylphosphate and nanofillers: natural montmoryllonite [MMT] – Nanofil®116, natural MMT modified with a quaternary ammonium salt - Cloisite®10A, synthetic layered silicate – Laponite®RD has been used in rigid polyurethane foams (PUFs). The influence of fillers amounts on processing parameters, physical–mechanical properties (compression strength, density, water absorption, brittleness, mass loss and volume change) and thermal properties (thermal stability and storage modulus in DMA methods) of such foams has been analysed. The morphology has been characterized by X-ray diffraction and scanning electron microscopy (SEM). The X-ray diffraction of the polyurethane nanocomposite foams has been indicated the partial exfoliation of the clay in the polyurethane matrix. The flame retardancy and the thermal stability of all polyurethane modified systems was improved by an addition of flame retardants or nanoclays. Best results, in comparison for pure polyurethane foam, was obtained for polyurethane modified with organically modified montmorillonite (Cloisite 10A).
Kinematic Approach for a Global-Local Coupling: Compressive Behaviour of a Delaminated Panel
Authors: Borrelli R. , Caputo F. , Riccio A. , Scaramuzzino F. , Sellitto A.
Published: January 2019

A kinematic approach to global/local coupling has been applied to investigate the behaviour of a delaminated stiffened composite panel, by using an in-house finite element based procedure. The delamination growth phenomenon has been simulated by employing fracture elements implemented in the B2000++® code, which are based on the Modified Virtual Crack Closure Technique (MVCCT); this technique is able to compute the energy release rate on the delamination front for each fracture mode. A very fine three-dimensional mesh in the delaminated region has been considered in order to obtain a good prediction of the delamination growth. The rest of the structure has been modelled by means of shell elements. A global/local approach based on point-wise multipoint constraint has been implemented in the in-house-code and used to connect shell meshes to solid ones. A numerical application on a delaminated composite stiffened panel taken from literature has been introduced. Models characterized by different levels of complexity, i.e. without delamination, with delamination, with delamination growth have been considered and compared to understand the effectiveness of the introduced kinematic approach.
Finite Element Analysis for Interfacial Crack in Piezoelectric Composite under Impact Loading
Authors: Wang Liang , Bai Rui-Xiang , Chen Hao-Ran
Published: January 2019

In this paper, a nonlinear finite element analysis of impact interfacial fracture for a piezoelectric composite is provided. The Newmark method was used to solve the dynamics equation. Virtual crack closure technique is to evaluate the energy release rate of crack tip. Contact elements were set up on crack surface and in the area in contact under impact loading to prevent the penetration between PZT and composite. The response curves of the energy release rate are obtained for piezoelectric composites. Numerical results are provided to show the effect of the piezoelectricity, the applied voltage, the stack sequence of composites and the contact of crack surface on the resulting dynamic energy release rate of piezoelectric composites.
Preparation and Physicochemical Evaluation of Paste-Paste Calcium Hydroxide Based Dental Cement and the Effect of Replacement of Glycol Disalicylate by Methyl Salicylate on its Basic Properties
Authors: Nezafati Nader , Hesaraki Saeed , Shahrezaee Mostafa
Published: January 2019

Dycal® is a paste-paste calcium hydroxide dental cement uses as pulp capping and liner in dentistry. First paste (base paste) contains titanium dioxide and barium sulphate in glycol disalicylate and second paste (catalyst paste) contains calcium hydroxide, zinc oxide and zinc stearate in ethyl toluene sulphonamide. Equal amounts of base and catalyst paste were mixed together and a hard mass is obtained after a certain time. The set material consists of TiO2, ZnO (fillers), BaSO4 (radiopacifier) and free unreacted Ca(OH)2 dispersed in an amorphous calcium phenolate matrix. This unreacted calcium hydroxide is responsible for biological properties of Dycal® (antibacterial and formation of reparative dentin).

In this research Dycal® has been fabricated and furthermore glycol disalicylate was gradually replaced by methyl salicylate up to 20 % in base paste. Cements were characterized by X-ray diffraction (XRD) and Fourier transform infra-red (FTIR) and scanning electron microscopy (SEM). Also effect of the replacement was investigated on setting time, water solubility, pH and compressive strength of the cement. Results showed that unreacted calcium hydroxide decreased in set cement when methyl salicylate increase in base paste and therefore, and pH of distilled water containing cement decrease by this replacement. Setting time and water solubility also decreased when methyl salicylate increased in base paste (from 5.5 to 3 min and 4.5% to 2.5% respectively). The compressive strength showed no changes by this replacement.
Vibrational Characteristics of Zigzag, Armchair and Chiral Cantilever Single-Walled Carbon Nanotubes
Authors: Jalan S.K. , Rao B. Nageswara , Gopalakrishnan S.
Published: January 2019

Finite element analysis has been performed to study vibrational characteristics of cantilever single walled carbon nanotubes. Finite element models are generated by specifying the C-C bond rigidities, which are estimated by equating energies from molecular mechanics and continuum mechanics. Bending, torsion, and axial modes are identified based on effective mass for armchair, zigzag and chiral cantilever single walled carbon nanotubes, whose Young's modulus is evaluated from the bending frequency. Empirical relations are provided for frequencies of bending, torsion, and axial modes.
The Dry Sliding Wear of Cenosphere -Aluminium Metal Matrix Composite
Authors: Saravanan V. , Thyla P.R. , Balakrishnan S.R.
Published: January 2019

In today's rapidly developing automobile and aeronautical industries, numerous composites are widely used for various applications. This increases the need for continuous research and development of a number of composites. This research work investigated various volume % of cenosphere reinforced AA6063 composites which were made by stir casting method. These composites were surveilled with the help of chemical analysis and scanning electron microscopy to ensure the distribution and bonding between reinforcement and matrix. The design of experiments (DOE) was used to plan the wear tests and the wear results were obtained. The dry sliding wear behaviour of composites was studied by means of a pin-on-disc wear test machine and the results were compared with pure AA6063. The influences of critical parameters such as applied load, sliding speed were evaluated. Enhanced wear properties were observed with addition of cenospheres in aluminium alloy. Disc brake rotor was cast with optimum amount of cenosphere % using sand moulding.
On Viscoplasticity Characterization of Natural Fibres with High Variability
Authors: Pupure Liva , Varna Janis , Joffe Roberts
Published: January 2019

Zapas model has shown good results in characterizing viscoplasticity in polymers and composites. Typically all viscoplastic parameters for this model are obtained in creep and strain recovery tests at different stress levels and at different test length. Obtaining parameters for highly variable bio-based materials is more challenging: trends are hidden in the scatter and data fitting is complicated. This paper suggests “single specimen methodology” for complete viscoplastic characterization and identification.
The Effect of the Boundary Conditions on the Impact Behaviors of Stitched Composite Lap Joints
Authors: Ergun Emin , Gökkaya Ismail
Published: January 2019

In this study, transverse impact behaviors of stitch adhesively bonded composite lap joints having three different overlap lengths (20, 40 and 60 mm) at different energy levels are investigated. The effects of the boundary conditions (clamped-clamped and clamped-free) and three different span lengths (40, 60 and 80 mm) have been determined. The impacts energies are varied in a range from 5 J to 20 J. Vacuum assisted resin infusion method (VARIM) is used to manufacture composite plates. It is shown that the boundary conditions and span lengths affect considerably the impact responses of the stitch composites lap joints. The important impact characteristics of the composite lap joints are compared with each other and discussed. The observed damages of the composite lap joints are presented.
Uncertainty Quantification in Natural Frequency of Composite Plates - An Artificial Neural Network Based Approach
Authors: Dey Sudip , Mukhopadhyay Tanmoy , Spickenheuer Axel , Gohs Uwe , Adhikari S.
Published: January 2019

This paper presents the stochastic natural frequency for laminated composite plates by using artificial neural network (ANN) model. The ANN model is employed as a surrogate and is trained by using Latin hypercube sampling. Subsequently the stochastic first two natural frequencies are quantified with ANN based uncertainty quantification algorithm. The convergence of the proposed algorithm for stochastic natural frequency analysis of composite plates is verified and validated with original finite element method (FEM) in conjunction with Monte Carlo simulation. Both individual and combined variation of stochastic input parameters are considered to address the influence on the output of interest. The sample size and computational cost are reduced by employing the present approach compared to traditional Monte Carlo simulation.
Water Absorption Behaviour and Impact Strength of Kenaf-Kevlar Reinforced Epoxy Hybrid Composites
Authors: Yahaya R. , Sapuan S.M. , Jawaid M. , Leman Z. , Zainudin E.S.
Published: January 2019

Fibre reinforced polymer composites has been used in a variety of applications. Recently, there is increasing interest in the research on natural-synthetic fibre hybrid composite. In this study, water absorption behaviours and impact properties of woven kenaf-Kevlar hybrid composite were evaluated. In all samples, Kevlar (aramid fibres) was kept as the skin layers and kenaf as the core material. The experimental results revealed that the hybrid composites with high kenaf content shows low density (0.88g/m3) and contains a high content of the voids (25.67%). Similar finding observed in water absorption and thickness swelling test as the hybrid composite with higher kenaf content absorb more water absorption and low dimensional stability. Water absorption affects the impact strength of the composites. The impact strength decreased about 45.38 % (from 228.24 to 124.66kJ/m2) in sample H1), whereas, the highest impact strength decreased of about 78.52% (from 179.71 to 38.60 kJ/m2) was observed in sample H5). The result of this study is important for the further utilisation of woven kenaf in hybrid laminate composites.
Microwave Sintered Magnesium Nanocomposite: Hybrid (Y2O3+Ni) Na-No-Size Reinforcement and Tensile Properties
Authors: Hassan S. Fida , Tun Khin Sandar , Patel F. , Al-Aqeeli Nasser , Gupta M.
Published: January 2019

In the present study, results revealed that strength of the microwave sintered commercially pure magnesium was significantly enhanced till 100°C due to the incorporation of hybrid (0.7 % yttria + 0.6 % nickel) nano-particle reinforcement, which diminishes gradually with a further increase in test temperature. Presence of the hybrid reinforcement particles assisted in complete recrystallization of magnesium matrix at 150°C. The hybrid reinforcement also assisted in the deformation process of magnesium and achieved large ductility at a relatively low temperature.
Synthesis and Analysis of Mn3O4@Graphene Nanocomposites for Supercapacitors
Authors: Zhu Mingfu , Fu Ruimin
Published: January 2019

An easy arc discharge method was developed to synthesize nanocomposites composed of Mn3O4 nanoparticles loaded on graphene sheets.

The morphology and structure of the obtained nanocomposites were analysed via X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The electrochemical behaviour of the product was evaluated via cyclic voltammetry and alternating current impedance. Results showed that Mn3O4 was dispersed homogeneously on the surface of graphene. The supercapacitor constructed by graphene/Mn3O4 as the positive electrode showed both high capacitance and good electronic conduction, which may lead to the development of nanocomposites with great potential for applications in biosensors and electrode material analysis.
The Effect of Nano Graphite Particle Content on the Wear Behaviour of ZA27 Based Hybrid Composites
Authors: Güler O. , Cuvalci H. , Canakci A. , Celebi M.
Published: January 2019

ZA27 based hybrid composites with dry lubricating particles and hard particles can be used for bearing applications with their good tribological properties instead of the traditional bearing materials. In this study, the wear behaviour of ZA27 based hybrid composites reinforced nano-graphite particulates and hard nano-alumina (Al2O3) particulates were investigated under dry sliding conditions. While the content of nano-alumina that is one of reinforced materials was selected in 4 vol. %, the contents of nano-graphite particulates were determined in different volumes (%1-%2-%3 and %4). The effect of graphite content was studied on wear behaviour under different sliding distance conditions. A block-on-disc sliding wear testing apparatus was used to carry out dry wear tests. The sliding distances was found to be significant parameter detecting effect of graphite content. The worn surfaces were investigated by scanning electron microscopy (SEM) and the wear mechanisms were identified. While the lowest wear loss was seen in hybrid nanocomposite with content of 4 vol. % graphite and 4 vol. % alumina, the highest wear loss was determined in ZA27. It was determined that abrasion is the dominant mechanism in all hybrid nanocomposites except for composite including 4 vol. % graphite and 4 vol. % alumina. However, the worn surface of the hybrid nanocomposite that is with content of 4 vol. % graphite and 4 vol. % alumina showed that adhesion is dominant as the wear mechanism.
Fabrication and Characterization of Biodegradable Composites from Poly (Butylene Succinate-Co-Butylene Adipate) and Taihu Lake Blue Algae
Authors: Xia Wenjing , Zhu Nianqing , Ni Zhongbin , Chen Mingqing
Published: January 2019

Biodegradable composites from poly (butylene succinate-co-butylene adipate) (PBSA) and Taihu Lake (Wuxi, China) blue algae were prepared by melt blending. The property and structure of biocomposites were investigated. By adding extra amount of water to blue algae, the formulated blue algae acted as a plastic in the composites during blending, and exhibited a reinforcing effect on the PBSA matrix. With increasing blue algae content, the thermal stability of the composites decreased; the tensile strength at break and elongation at break of the composites reduced, but the Young's modulus of the composites increased. However, the composite with 30% blue algae loading still exhibited good mechanical performance (tensile strength at break of 21.3 MPa, elongation at break of 180%). The fabrication of value-added PBSA/algae composites appeared as an effective approach to reduce the secondary environmental pollution of Taihu blue algae.
Micromechanical Analysis of the Fibre-Reinforced-Epoxy Composites with Nanoparticles Embedded in the Interphase Region under Transverse Compression
Authors: Wang Zhen-Qing , Li Hao , Sun Xiao-Yu
Published: January 2019

The mechanical behaviours of fibre reinforced epoxy matrix composites with silica nanoparticles inserted between fibres and matrix subjected to transverse compression are studied by computational micromechanics. A series of representative volume elements of composite microstructures containing fibres, nanoparticles with different distribution types, volume fractions and Young’ modulus; and matrix are established. The effect of nanoparticles incorporated in the interfacial phase on the elastic-plastic behaviour of composites has been assessed. The stress versus strain relationship, ductility and compressive strength are determined by the finite element analysis. It is found that the material property, volume fraction and distribution type of nanoparticles have significant influences on the mechanical behaviour of composites. The large plastic deformation between the fibre and nanoparticles can consume considerable deformation energy, which will enhance the mechanical behaviour of composites.
Effect of Moisture on Mechanical Properties and Fracture Behavior of Carbon Fiber Reinforced Polymer Composites
Authors: Selzer R , Friedrich K
Published: January 2019

This investigation deals with the effect of moisture on the mechanical properties of carbon fiber reinforced polymer composites. Relationships between fracture-features and corresponding mechanical data are evaluated. The more the mechanical properties depend on the matrix and the interface, the more these properties are influenced by moisture.
Studies on Electromagnetic Wave Functional Composites Containing Resonator
Authors: Gan Y X , Chen C Q
Published: January 2019

Electromagnetic wave (EM wave) functional composite materials containing metal–coated carbon fibers (MCFs) and lossy dielectrics have been investigated. Electromagnetic wave decay model of the composites was set up by transmission line simulation and field analysis. Transformation of absorption to reflection of electromagnetic wave of the composite materials are also concerned.
The Microstructure of Low Oxygen Nicalon Fibre
Authors: Berger M.H. , Bunsell A.R.
Published: January 2019

Fibers in the Nicalon series based on SiC but having a very low oxygen content (0.4% wt) have recently been produced by Nippon Carbon by curing the polycarbosilane precursors with an electron beam instead of thermal oxidation. The microstructure of the fibre has been studied by TEM and, as in the NLM 202 fibre found to consist of C particle of 2–3 nm and SiC crystallites, but with larger dimensions (10–20 nm compared to 3 nm) due to the absence of a continuous Si-O-C intergranular phase.
Toughening Effect of a China – Made Polyaryletherketone on Polyphenylene Sulfide
Authors: Zhang M Q , Zeng H M , Mai K C , He Y T
Published: January 2019

The present investigation deals with an attempt to improve the toughness of polyphenylene sulfide (PPS) through blending with a China - made polyaryletherketone (PEK - C). It is found that on certain processing conditions PPS can be made very tough in the case of lower PEK - C content. On the basis of mechanical performance measurement and fractographic analysis, the toughening mechanism is discussed tentatively.