bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Finite Fracture Mechanics Approach for Assessing the Strength of Bonded Lap Joints
Authors: Weißgraeber Philipp , Becker Wilfried
Published: February 2011

For the widespread use of adhesive joints an exact and reliable prediction of the strength is mandatory. In this work, a new approach to assess the strength of single lap joints is presented. The approach is based on the hybrid criterion as postulated by Leguillon in the framework of finite fracture mechanics. It strictly combines a consideration of an energy release balance and a fulfillment of a strength criterion. The present work is based on a simple model of the joint behavior and assumptions about crack initiation. From the stress distribution of the classical shear lag theory an incremental energy release rate is derived and is used to formulate the optimization problem of the failure load. The resulting predictions of critical failure loads are compared to experimental results of single lap joints. It is shown that the new approach is able to physically describe crack formation and the corresponding critical load within the framework and limitations of the underlying assumptions and simplifications. The work closes with a discussion of the limitations and an outlook on possible improvements of the underlying models and assumptions.
Metal Matrix Composites: Solidification Parameters of Aluminium-11.8% Silicon Alloy Reinforced with Titanium Carbide Particulates
Authors: Fatchurrohman N. , Sulaiman Shamsuddin , Arifin Mohd Khairol A. , Faieza A.A. , Baharudin B.T. Hang Tuah
Published: February 2011

In this study, solidification analysis of metal matrix composite, aluminium-11.8% silicon alloy matrix reinforced with titanium carbide particulates is performed. Sand casting method is used as the manufacturing method to produce the specimens. Thermal measurements during the casting process are captured and solidification graphs are plotted to represent the solidification characteristic. Solidification analysis is performed by interpreting the solidification graphs. Parameters such as; the nucleation of primary alpha phase temperature, liquidus arrest temperature, liquidus undercooling, eutectic growth temperature and solidification time are presented. The results show that introduction of second phase particulates into a matrix alloy have affected the various time and temperature parameters of its solidification properties.
Parametric Study on Cohesive Element for Composite Fuselage Model
Authors: Sim N.W. , Mustapha Faizal , Varatharajoo Renuganth , Zahari Rizal , Majid D.L.
Published: February 2011

In this paper, a numerical simulation on a new fabrication miniature composite fuselage structure- a woven composite laminated with an adhesively bonded butt joint under the axial compression loading is presented. A FEA via Abaqus/Explicit was utilized to capture the complete compressive responses to predict the crushing behaviour and its mechanical strength from the initial compression loading till its final failure mode. A woven C-glass fiber/epoxy 200 g/m2 composite laminated [908] with the orthotropic elastic material properties is modeled as a continuum composite layup in the proposed numerical model. The adhesively bonded joint progression was modeled using the cohesive element technique. The proposed model was used to observe the crushing load and collapse modes under the axial compression impact. The finite element results showed a good agreement with the experimental results under the actual quasi-static tests. The validation code was extended to further undergo parametric studies in order to visualise the effect of angle orientations and special laminate cases as to attain the optimum design criteria for the proposed composite structure.
Effects of Different Particles Sizes of Graphite on the Engineering Properties of Graphites/Polypropylene Composites on Injection Molding Aplication
Authors: Iswandi Iswandi , Sahari Jaafar , Sulong Abu Bakar
Published: February 2011

The injection molding of polymer composite is one of the promising and practical methods in the manufacturing of bipolar plates in mass production. Graphite filler with higher loading concentration is mainly used for this purpose. The particle size and composition (wt. %) of graphite filler material influences on the mechanical properties and electrical conductivity of composite materials. The main challenge is the reduction of flow ability during injection of high load filler material. Flow ability of feedstock material is an important factor in the process of injection molding. This paper presents a development of the rheology approach on the effect of particle size in material flow ability occurs in the injection molding process. Polypropylene (PP) as polymer matrix and graphite as conductive filler mixed together with different size to form feedstock material. Graphite purchase from local Asbury Graphite Mills, Inc, grade 3243 with particle size in average after sieve of ≤40, ≤100, and ≤150 μm. Proportions of polymer matrix and graphite at (PP / G) 25 / 75 wt. %. Mixing of graphite in PP matrix is done using an internal mixer (Thermo Haake) at 50 rpm, temperature at 200 oC. Rheology behaviors of graphite composite were measured using a capillary rheometer type Shimadzu CFT-500D, with a diameter 1 mm and length 10 mm. The fracture surface morphology was examined using scanning electron microscopy (SEM). The electrical conductivity of composite materials was measured by the four point probe. The hardness property measurement of conductive material composite was performed using a Dynamic ultra micro hardness tester using a Vickers typed diamond indenter. The results indicate that the level of viscosity and shear rate on all eligible mixed particle size capable of injectable. The properties of composite materials is the highest in three mix particle size (40/100/150 μm) for the electrical conductivity of 9.13 S.cm-1 and hardness at 34.3 HV. Viscosity of 56 Pa.s at a temperature of 200 oC and shear rates generated in 3231 s-1. The highest electrical conductivity for a single particle size is 49.2 S.cm-1 at 150 μm and hardness of Vickers to 47.2 HV at 100 um. The highest electrical conductivity and hardness due to the packing density and reinforcement different particle size.
Selection of Polymeric Based Material Composite for Fibreglass Boat Components Using Expert System
Authors: Fairuz A.M. , Sapuan S.M. , Zainudin E.S.
Published: February 2011

In new era in marine industries especially in fibreglass boat construction, a proper material need to be consider for the product perfomance and economical. This paper ilustrate how the selection has been perform to select most suitable material for related body and structure component of fibreglass boat. Expert System has been using as a tool of selection and polymeric based material reinforced with different composition of fibreglass as candidate material. Ranking system has been implemented according to various factors to reveal the best polymeric based material composite for each fibreglass boat component.
Mechanical and Morphological Properties Evaluation of HDPE/Organoclay Nanocomposites with Various Percentages of NR Content
Authors: Zawawi Engku Zaharah Engku , Sahrim Ahmad Haji , Rashid Rozaidi
Published: February 2011

Nanocomposites prepared from blend of high density polyethylene (HDPE), natural rubber (NR) and organoclay were melt compounded using an internal mixer. The phase morphology and mechanical properties of this thermoplastic natural rubber nanocomposites samples were examined. The transmission electron microscope (TEM) and wide angle X-ray scattering (WAXS) was used to determine the exfoliation of organoclay in this blend. The tensile and Izod impact test were used to evaluate the mechanical properties of HDPE/organoclay nanocomposites with and without the presence of NR. The Izod impact results shows an improvement more than 300% with addition of 10% NR content in the matrix. The X-ray diffraction results indicated intercalation of blend into the silicate interlayer of nano-filler I.44P and partially exfoliation of silicate layer into the blend. The SEM morphology revealed that there was some part of uneven dispersion of organoclay in the blend.
Influence of Crystallite Size on Consolidation of Carbon Nanotube Reinforced AA 4032 Composite Powders by Equal Channel Angular Pressing
Authors: Saravanan M.S. Senthil , Sivaprasad Katakam , Kumaresh Babu S.P.
Published: February 2011

Equal channel angular pressing (ECAP) is the one of the promising methods of severe plastic deformation to obtain bulk ultrafine grain structures. However, ECAP can also be used for powder consolidation. In the present study, fully dense bulk AA 4032 alloy was consolidated from nanocrystalline and microcrystalline powders. These materials were processed by ECAP until four passes at ambient temperature. It is observed that hardness and densification increased significantly with increase in number of ECAP passes. Transmission electron microscopic and scanning electron microscopic examinations evidenced that crystallite size of the nanopowders are unaltered, however a significant crystallite size reduction from around 50 µm down to submicron size is observed. Moreover, higher densification is achieved in microcrystalline powders than nano powders, whereas higher hardness in the case of nanopowders compared to microcrystalline powders.
Optimal Sintering Procedure to Fabrication of Functionally Graded Hydroxyapatite-Titanium
Authors: Shahrjerdi Ali , Mustapha Faizal , Sapuan S.M. , Bayat M. , Abdul Majid Dayang Laila Abang , Zahari Rizal
Published: February 2011

Functionally graded metal-ceramic composite was fabricated by pressure-less sintering. The pure metallic component (Ti) and the pure ceramic component (HA) were located at the ends of a cylindrical specimen. Titanium and-Hydroxyapatite were utilized as a metallic and ceramic layer. The target sample thickness was 6 mm with radius cylindrical 20 mm. The sample was made from the cylindrical type of carbon die consisting of 5 layers. The composition of layers were 100%Titanium; 75 % Titanium +25% HA; 50% Titanium +50% HA; 25% Titanium+75% HA, and 100% Hydroxyapatite. The optimum thermal load mapping was obtained experimentally. The properties of all FGM products were characterized by shrinkage, optical-microscope, energy dispersive spectrometry (EDX) scanning electron microscope (SEM). The grade of the FGM material was proven by comparing amount of shrinkage after sintering. Result from optical micrograph, SEM and EDX indicated that the HA-Ti FGM could be produced successfully by using the optimal sintering procedure that was highlighted in this paper.
Effects of Antioxidants Content on the Physical and Mechanical Properties of Wood Plastic Composites
Authors: Ab Ghani Mohd Hafizuddin , Sahrim Ahmad Haji
Published: February 2011

We investigated the effects of amount of antioxidants variability on selected mechanical and physical properties of wood plastic composites. Recycled high density polyethylene (rHDPE) and natural fibers were compounded into pellets by compounder, then the pellets were extruded using co-rotating twin-screw extruder and test specimens were prepared by hot and cold press process. From the study, samples with 0.5 wt% of antioxidants produce the highest strength and elasticity of composites. The effect of antioxidants presence on water uptake is minimal.
Effect of Wet Oxidation on the Dispersion and Electrical Properties of Multi-Walled Carbon Nanotubes/Epoxy Nanocomposites
Authors: Royan R. Nishata , Sulong Abu Bakar , Suherman Hendra , Sahari Jaafar
Published: February 2011

Carbon nanotubes (CNTs) have excellent mechanical and electrical properties than conventional materials (carbon black and glass fibers), and are promising candidates as reinforcement material for composites. Formation of electrical conductive with effective dispersion of filler remains a main challenge in the polymer matrix and fillers in order to achieve a good electrical conductivity. Therefore, one of the solutions is to functionalize through wet oxidation of the CNTs besides adding surfactants or assisted liquids. Functionalization of CNTs involves the generation of chemical moieties on their surface that can improve the solubility and processibility. Any functionalization that is undertaken must preferably not influence other key properties such as strength and electrical conductivity of the nano-composite. The matrix used in this study was epoxy and reinforcement filler was multi-walled carbon nanotubes (MWCNTs). MWCNTs were treated with sulfuric acid and nitric acid at 3:1 (v/v) ratio. The present of functional groups on CNTS were investigated using Fourier Transform Infrared (FT-IR). Different weight percentages of MWCNTs (functionalized and as produced) / epoxy composite were prepared. The electrical conductivity of functionalized MWCNTs nanocomposites and as produced MWCNTs nanocomposites were measured by the four point probe. Dispersion state of CNTs in epoxy matrix was observed on fractured surface by scanning electron microscopic. Functionalized CNTs gave better dispersion stability in solvents than non-functionalized CNTs. As expected, non- functionalized CNTs (as produced MWCNTs) are not dispersed at all in all the solvents. However, functionalized CNTs composites give low electrical conductivity. Defects from acid treatment are assumed will damage the original chirality of as produced CNTs and give unbalance polarization on the CNTs, which are the reasons for no formation of conductive pathway networks of acid treated CNTs under electric field.
Tensile and Impact Properties of Sugarcane Bagasse/Poly(vinyl Chloride) Composites
Authors: Wirawan Riza , Sapuan S.M. , Abdan Khalina , Yunus Robiah Bt.
Published: February 2011

Sugarcane bagasse is divided into two main components, pith and rind, with “pith” representing the inner part of the sugarcane bagasse and “rind” as the outer part. In this study, the tensile and impact properties of untreated pith/ poly(vinyl chloride) composites were compared to that of untreated rind composites using the same matrix with variation of fibre content. It was observed that the tensile strength and modulus of rind/PVC composites are higher than the unfilled PVC at composite fibre contents of 30% and 40%. Additionally, the rind composites exhibited superior strength and stiffness in comparison with the pith composites.
The Effect of Alkali Treatment Mechanical Properties of Kenaf Fiber Epoxy Composite
Authors: Mutasher Saad A. , Poh Adrian , Than Aaron Mark , Law Justin
Published: February 2011

Increasing worldwide environmental awareness is an encouraging scientific research into the development of cheaper, more environmentally friendly and sustainable construction and packaging materials. Kenaf fibre is a natural fibre which is growing in popularity due environmental issues and its properties as filler. Epoxy is a versatile thermosetting polymer which has a low curing temperature and used in making carbon fibre and glass composites. In this paper the properties of kenaf bast fibre epoxy reinforced composite have been investigated. The effects of alkali surface treatment of the fiber on the composite properties are also investigated. A hand layup method was use to fabricate the test specimens. Generally, all the treated fibre composites performed better than the untreated fibre with an improvement approximately 5% to 10%. Epoxy has the highest tensile strength and flexural strength among all specimens. The 24wt% treated kenaf fibre composites has the highest tensile strength, 27.72MPa and flexural strength, 56.91MPa. The kenaf fiber weight fraction of 40% gave the highest impact strength. The impact strength of the 40wt% kenaf fiber increased 14.3% after alkali treatment.
Effect of Organic Modification of Muscovite on the Polypropylene Layered Silicate Nanocomposite
Authors: Ahmad Rasyid Mohd Fadli , Hazizan Md Akil , Sharif Jamaliah Mohd
Published: February 2011

Polypropylene- layered silicate nanocomposite based on muscovite was prepared via melt compounding. Muscovite was organomodified with cetyltrimethylammoniumbromide (CTAB) by using different filler loading. The effects of muscovite content on mechanical and morphology properties were evaluated. Analysis of test data showed that the mechanical properties increased with an increase in filler loading up to a threshold of 3 wt%; thereafter the material properties were degraded. The enhancement of properties attributed to the formation of intercalated and exfoliation nanocomposite structure at these loadings of clay. At higher filler loading, degradation in mechanical properties maybe attributed to the formation of agglomerated clay tactoids.
Fabrication and Characterization of Unidirectional Silk Fibre Composites
Authors: Ahmed Mansur , Islam Md. Saiful , Ahsan Qumrul , Islam Md. Mainul
Published: February 2011

Natural fibres offer a number of benefits as reinforcement for synthetic polymers since they have high specific strength and stiffness, high impact strength, biodegradability etc. The aim of this study is to fabricate and determine the performance of unidirectional silk fibre reinforced polymer composites. In the present initial study, alkali treated silk fibres were incorporated as reinforcing agent, while a mixture of 20% maleic anhydride grafted polypropylene (MAPP) and commercial grade polypropylene (PP) was used as matrix element. The unidirectional composites were fabricated by using hot compression machine under specific pressure, temperature and varying fibre loading. Tensile, flexural, impact and hardness tests were carried out by varying silk fibre volume fraction. Composites containing 45% fibre volume fraction had higher tensile and flexural strength, Young’s modulus and flexural modulus compared to other fabricated composites including those with untreated silk fibres. SEM micrographs were taken to examine composite fracture surface and interfacial adhesion between silk fibre and the matrix. These micrographs suggested less fibre pull out and better interfacial bonding for 40% fibre reinforced composites.
Evaluation of Corrosion Properties of Electroless NiP/Nano-SiC Composite Coatings
Authors: Zarebidaki Arman , Allahkaram Saeed Reza
Published: February 2011

Ni-P/nano- SiC composite coatings were deposited in different concentrations of SiC nano-particles in the bath. The hardness and corrosion resistance of the composite coatings with different content of SiC nano-particles were measured. Moreover, the structure of the composite coatings was investigated by means of X-ray diffraction (XRD), while their morphologies and elemental composition were analyzed using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). Results showed that co-deposited SiC nano-particles contributed to increase the hardness but corrosion resistance of electroless Ni-P coatings decreased due to agglomeration of nano-particles and increasing porosity of coatings.
Thermal Properties and Thermal Degradation Kinetics of Polypropylene/ Organomodified Ni-Al Layered Double Hydroxide (LDH) Nanocomposites Prepared by Melt Intercalation Technique
Authors: Kakati Kaberi , Prakash Aditya , Pugazhenthi G.
Published: February 2011

The objective of this work is to investigate the influence of LDH loading on the thermal stability and thermal degradation kinetics of the PP/Ni-Al LDH nanocomposites using thermogravimetric analysis (TGA) and to compare the results with that of the neat PP. For this, Ni-Al LDH was first prepared by co-precipitation method at constant pH using their nitrate salts and subsequently organically modified using sodium dodecyl sulphate (SDS) by regeneration method. A series of novel PP/Ni-Al LDH nanocomposites was then prepared with various amounts of LDH by melt intercalation method. The XRD results confirm the formation of exfoliated PP/LDH nanocomposites. PP/LDH nanocomposites exhibit enhanced thermal stability relative to the neat PP due to the presence of barrier effect of LDH lamellar layers and the thermal stability of the nanocomposites also increases with increase in the LDH loading. When 10% weight loss is selected as a point of comparison, the decomposition temperature of PP/LDH (5 wt %) nanocomposite is 15 oC higher than that of neat PP. The thermal degradation activation energy of the nanocomposites is determined via Coats-Redfern method and compared with that of neat PP. The improvement of thermal stability of PP nanocomposites is also confirmed by increasing the activation energies (Ea) and the integral procedural decomposition temperature (IPDT) compared with neat PP. Criado method is finally used to determine the degradation reaction mechanism of various samples.
Investigation on Improvement of Mechanical Properties of Kenaf / E-Glass Fiber Composites by Mercerization Process
Authors: Ya’acob Abdul Malek , Bakar Azhar Abu , Hanafi Ismail , Zaman Dahlan Khairul Mohd.
Published: February 2011

A hybrid composites mechanical properties consisting of un-treated and treated bast Kenaf fiber and E- glass fiber was investigated by varying the fiber glass weight ratio and using interplay fabrication method. A further comparison was made with corresponding properties of 100% wt E-glass fiber composites sample. The expected results were to have better composites performance in terms of toughness and impact strength as a comparison between the E- glass fiber reinforced composites and Kenaf fiber reinforced composites alone. All samples are prepared using typical samples preparation techniques. Result shows that the incorporation of E – glass fiber resulted in brittle failure and a higher amount of E-Glass fiber with low percentage of Kenaf fiber resulted in high strength, low ductile and low toughness behavior.
Influence of Cutting Parameters on Surface Roughness for Wet and Dry Turning Process
Authors: Yusuf Muhammad , Anuar Khairol , Ismail Napsiah Binti , Sulaiman Shamsuddin
Published: February 2011

This paper presents a study of the quality of a surface roughness model for mild steel with coated carbide cutting tool on turning process. The experiments were carried out under wet and dry cutting conditions. The model is developed based on cutting speed, feed and depth of cut as the parameters of cutting process. This research applies the fractional factorial design of experiment approach to studied the influence of cutting parameters on surface roughness. The measured results were collected and analyzed using commercial software package called Minitab. Analysis of variances is used to examine the influence of turning factors and factor interactions on surface roughness. The result indicated that, there are inherent differences in surface roughness between wet and dry cutting process with the same parameters process model. Analysis of variance was found that feed parameter is the most significant cutting parameter, which influences the surface roughness. The most significant interactions were found between cutting speed and feed parameters for dry turning process. Therefore is a significant effect of using combination of the fluid for cooling the cutting operation.
Development of Biocomposite Wall Cladding from Kenaf Fibre by Extrusion Molding Process
Authors: Khalina Abdan , Zainudin E.S. , Faizal Abdul Rahman Mohd , Jalaluddin H. , Umar A.H. , Syuhada W.N.W.N.
Published: February 2011

Nowadays, natural fibre-thermoplastics composites (NFPC) are replacing the conventional wood and timber due to its lower cost, avoid deforestation, higher strength-to-weight ratio and resistant to termites. These composites can be utilized for non-structural components of a building system such as decking, wall cladding, floor tiles and window frame. A natural fiber/plastic composite was produced by extrusion molding process to create a wall cladding profile. The raw materials used for the composites are 40% kenaf fibre and 60% polypropylene (PP). These materials were compounded through a twin-screw extruder and then cut into pellets. The moisture content found in the kenaf/PP composites (KPC) pellets was 2.89%. Therefore, the pellets required to be oven dried every time right before entering the hopper of the extruder. The temperature along the barrel was set to 180°C and the die head temperature is set to 165°C. At the end of the extrusion molding process, pressurized air was used for cooling the profile. Then, samples of the wall cladding were taken back to the laboratory for product quality assurance. Measurements of the samples show that the product experiences 3% of shrinkage in term of width and 1% of shrinkage in term of thickness. Water absorption test indicates an increase of 13.6% of weight after 24 hours immersion of water. Impact strength test was also conducted on the wall cladding samples and the mean result was 2.55 kJ/m². Tensile test on the extruded KPC product indicates a low tensile strength at 4.51 MPa and tensile modulus of 205.01 MPa. The sample also proven to be light weight as the density of the material was found to be 0.618g/cm³.
Characterisation and Properties of Sintered Recycled Glass Utilising CIP Method
Authors: Rosli N.R. , Mohd Juoi Jariah , Shaaban A. , Ayoob N.F.
Published: February 2011

Recycling glass is chosen as an alternative raw material in upgrading ceramic into glass ceramic. The main objectives are to determine the effect of sintering temperature and the recycled glass to ball clay weight ratio on glass ceramic produced from recycled glass. The recycled glass powders are prepared by crushing and grinding waste glass bottles to a particles size distribution below than 75 µm. The raw materials (recycled glass powder and ball clay) are characterised by Differential Thermal Analysis (DTA) and its composition is determine by X-Ray Fluorescence (XRF). The recycled glass powder are then mixed with the ball clay according to the ratio of SLSG to ball clay of 95:5 wt.%, 90:10 wt.% and 85:15 wt.%. Green samples of glass ceramic are then fabricated using Cold Isostatic Pressing (CIP) with constant pressure at 40 MPa. Sintering process is conducted at three different temperatures at 750°C, 850°C and 950°C with 1 h holding time. The sintered glass ceramic were then characterised using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. Results of physical analyses and microhardness testing conducted according to ASTM C 373 and ASTM C 1327 showed that better properties is achieved at batch composition compromised of 85:15 wt.% ratio of recycling glass to ball clay and sintered at 850 °C. SEM micrographs showed that samples produced from this optimum batch composition provide more homogeneous and dense surface. Furthermore, XRD analysis indicates that crystalline phases evolved during sintering contributes to the final strength of the glass ceramic. These encourage further development on the glass ceramic samples which intended for structural applications.
Oscillatory and Creep Recovery Test on Nano-Composite Lead-Free Solder Pastes (Nickel and Platinum Powder)
Authors: Durairaja R. , Leong Kau Chee , Wea Lim Chia , Chu Wong Mee
Published: February 2011

This study investigates the relationship of rheological properties of nanoparticles added to lead-free solders paste. For lead-free solder paste, a large number of combinations can be made from different elements. Every ingredient plays a role of the paste and the rheological properties. The effect of filler concentration was studied in this present investigation. Creep recovery, stress is applied on samples for a period of time and later release in order for it to recovery itself. In the other words, creep recovery involves a tensile specimen under constant load maintained at a constant temperature. Oscillatory tests were carried out to study the visco-elastic behaviour and paste stability. The visco-elastic behaviour of the paste lies between solid and liquid characteristic of the paste, which could be used to study the flow behaviour of paste during stencil printing process. From this study, it was found that the solid characteristic, G' is higher than liquid characteristic, G'' for all the samples. In addition, the results from the study showed that the 0.06 volume fraction sample system with a large yield point which G'= G'' has a higher cohesiveness and hence resulting in poor withdrawal of the paste during stencil printing process. The phase angle, δ was used to correlate the quality of the dense suspensions to the formulation of solder paste materials. Lower value of phase angle for 0.06 volume fraction sample system may indicating that the paste is very tacky compare to the other samples. As the demand for lead-free pastes increases rheological measurements can assist with the formulation of new pastes.
Progressive Damage Analyses of Composite Laminates Exhibiting Free Edge Effects Using a New Micro-Meso Approach
Authors: Hosseini-Toudeshky Hossein , Farrokhabadi Amin , Mohammadi Bijan
Published: February 2011

In this paper, the developed new micro-meso method by the authors is used for the edge-effects analyses of various angle-ply laminates such as [10/-10]2s and [30/-30]2s. It is shown that the obtained stress-strain behaviors of laminates are in well agreement with the available experimental results. The stress variations through the laminate thickness and near the free edges are also computed and compared with the available CDM results.
Fabrication and Characterisation of La0.6Sr0.4Co0.2Fe0.8O3-δ-SDC Composite Cathode
Authors: Rahman Hamimah Abdul , Muchtar Andanastuti , Muhamad Norhamidi , Abdullah Huda
Published: February 2011

Composite cathode is a promising material to be used as electrodes in fuel cells. The fabricated composite cathode materials in this study are comprised of a mixture of submicron La0.6Sr0.4Co0.2Fe0.8O3- (LSCF6428) powders with two types of nanoscale ionically conducting ceramic electrolyte materials, samarium-doped ceria (SDC) and SDC-carbonate (SDCc). 30 – 50 wt% of electrolyte materials are added to the LSCF6428 cathode via the solid state method. The composite powders were ball-milled in ethanol and calcined at the temperature range of 800°C to 900°C for 2 hours in air. The composite cathode powders are characterised in terms of morphology and crystal structure. It is found that after calcining, the LSCF and the electrolyte materials retained their original structures as there was no chemical reaction between the two components. In addition, the LSCF-SDC composite cathode powders were found to exhibit a narrower distribution in size compared to the LSCF-SDC carbonate powders.
LiCF3SO3 – CeO2 Composite Electrolytes Prepared by Sol-Gel Technique: Structural and Conductivity Studies
Authors: Dzulkurnain N.A. , Nor Sabirin Mohamed
Published: February 2011

(100-x) LiCF3SO3 + (x) CeO2 composite electrolytes were prepared using sol-gel technique followed by sintering at 300 °C for four hours. Structural property and conductivity of the prepared composite electrolytes were studied using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX) analysis and Impedance Spectroscopy. The XRD spectra show only crystalline peaks of CeO2 indicating that LiCF3SO3 exists in the form of amorphous phase. This is confirmed by SEM and EDX analyses. The highest ionic conductivity at room temperature is found to be in the order of 10-3 S cm-1 for the composite of 70 mol % LiCF3SO3 - 30 mol % CeO2. The conductivity of the composite electrolytes is observed to increase gradually with temperature.
Field Layout of Glass Reinforced Epoxy Pipeline – A Practical Approach
Authors: Seibi Abdennour , Pervez Tasneem , Qu Xiao Liang , Khalaf Adel
Published: February 2011

This paper presents a practical approach dealing with the development of safe working envelops for field operators to avoid any potential GRE pipe failure during installation. Finite element modeling was used to model the pipeline. Two different element types available in ANSYS library (Beam and Shell elements) were used in the analysis. Various pipe sizes subjected to typical loading conditions similar to field layout conditions were considered. The finite element models were used to estimate pipe deflection, the internal normal and shear forces as well as bending moments for each pipe section along its length from which the induced stresses were determined. The maximum tensile stress was calculated and compared to the failure strength of GRE for various lifting scenarios. A sensitivity analysis on the various parameters affecting the structural integrity of the pipeline was also performed. It was found that the beam element over predicts the threshold lifting height as compared to the shell element results. In most cases, the estimated threshold value for the lifting height causing potential pipe failure for all pipe sizes is 2 and 1.2 m for beam and shell elements, respectively. Moreover, the results showed that the minimum threshold height increases for smaller pipe sizes.
Effect of Hydroxyapatite Reinforced High Density Polyethylene Composites on Mechanical and Bioactivity Properties
Authors: Husin Muhamad Rasyidi , Wahit Mat Uzir , Kadir Mohammed Rafiq Abdul , Rahman Wan Aizan Wan Abd.
Published: February 2011

The biomaterial composites consisting of a polymer with a matrix addition of particulate bioactive phase that analogous to the bone microstructure had been extensively studied as a substitute for human’s hard and soft tissues. In this work, HA reinforced HDPE composite (HDPE/HA) was made, with HA contents being up to 50 phr using single screw extruder nanomixer for the compounding process, and later followed by the injection moulding. These characteristics of the HDPE/HA composites were examined using various techniques including differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile testing. Mechanical and thermal properties of the composite are differed when the amount of HA incorporated into the composite were varied. It is shown that HA particles were well dispersed and homogeneously distributed within the HDPE matrix. The elastic modulus and tensile strength were increased when the HA volume percentage increased from 10 phr to 50 phr with corresponding decreases in elongation at break. However no significant influence on thermal stability was found with increasing HA loadings. The enhancement of bioactivity has been proved while incorporation of HA into HDPE composite. SEM-EDX image showed the bulk formation of apatite layers on the composite surface with 30 wt% HA after 7 days immersed in simulated body fluid (SBF) solution. These results suggest the great potential of the composites for a range of temporary application in which bone bonding ability is a desired property.
Microanalysis Techniques for the Investigation of Interphases Formed between Thermoset and Thermoplastic Polymers: Scanning Electron Microscopy and Energy Dispersive X-Ray Analysis
Authors: Heitzmann Michael , Hou Meng , Veidt Martin , Paton Rowan , Rasch Ron
Published: February 2011

Prepreg resin systems are typically of complex composition and require very specific manufacturing conditions. These characteristics restrict the use of some commonly used micro analysis techniques. This paper investigates the use of low acceleration voltage scanning electron microscopy and energy dispersive x-ray analysis for the characterization of diffused polymer interfaces. It is shown that, by operating at the dynamic charge balance, high resolution secondary electron images of polymer interfaces can be obtained and that conductive coating is not required. In addition, the effect of acceleration voltage on the interaction volume in EDX analysis is discussed using Monte Carlo simulation. X-ray intensity measurements in combination with afore mentioned Monte Carlo simulation is used to define practically obtainable spatial resolution limits. It is shown that by reducing the acceleration voltage below 5kV spatial resolution higher the 500nm can be obtained.
Fundamental Frequency Optimization of Laminated Cylindrical Panels by Elitist-Genetic Algorithm
Authors: Sadr-Lahidjani Mohammad Homayoun , Bargh Hadi Ghashochi
Published: February 2011

In this paper, fundamental frequency optimization of symmetrically laminated cylindrical panels is investigated by the Elitist-Genetic algorithm (E-GA). The number of layers, the fiber orientation angles, edge conditions, length/width (a/b) and length/R (a/R) ratios are considered as design variables. The classical shallow shell theory (Donnell’s formulation) is applied to calculate the natural frequencies of laminated cylindrical curved panels. To improve the speed of the optimization process, the elitist strategy is used in the Genetic algorithm and the fitness function is computed with a semi-analytical finite strip method (FSM). A program based on Maple is used for this purpose. To check the validity, the obtained results are also compared with some other stacking sequences.
Poly(vinylidene Fluoride)/Microcrystalline Cellulose Nanocomposites with Enhanced Compatibility and Properties
Authors: Tang Xue Gang , Hou Meng , Zou Jin , Truss Rowan
Published: February 2011

Poly(vinylidene fluoride)/Microcrystalline cellulose (MCC) nanocomposites were prepared by ultrasonic treatment and magnetic stir. Poly(vinylidene fluoride)-graft-maleic anhydride (PVDF-g-MAH) was added to promote matrix–filler compatibility. Transmission electron microscopy (TEM) results showed that the diameter of the MCC was decreased to several tens nanometers by the treatment of ultrasonic and magnetic stir. The results of differential scanning calorimetry (DSC) showed that the peak crystallisation temperatures (Tc) and the crystallisation enthalpy ΔHc increased with the addition of MCC, and the melting enthalpy ΔHm increased. With the addition of the compatibilizer (PVDF-g-MAH), peak crystallisation temperatures increased further, while without further increase of the ΔHc. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) showed that the addition of MCC induced β-phase PVDF, and the addition of PVDF-g-MAH can induce more β-phase PVDF. Mechanical properties of the nanocomposites were evaluated and the results showed that the addition of MCC did not increase the Young’s modulus, while the tensile strength and elongation at break decreased.
Simultaneous Optimization for Multiple Responses on the Compression Moulding Parameters of Composite Graphite – Polypropylene Using Taguchi Method
Authors: Selamat Mohd Zulkefli , Sahari Jaafar , Muhamad Norhamidi , Muchtar Andanastuti
Published: February 2011

This research concerns the effect of compression molding parameters on conducting polymer composite (CPC) properties such as electrical conductivity and flexural strength. In the present work on CPC, focus is given to graphite (G) as filler and polypropylene (PP) was use as the binder. The Taguchi’s L9 orthogonal array has been used as design of experiment (DOE) while the electrical conductivity and flexural strength were assumed to be quality characteristic (responses). The electrical conductivity was measured using four point probes and flexural strength was measured using three point tests according to ASTM D638. Classical analysis of variance (ANOVA) was used to investigate the significant of each compression molding parameters and finally propose the optimum compression molding parameters. But for several responses, the optimum condition for one response is not very likely to the optimum condition for other response.
Modeling and Analysis of Elastoplastic Impacts on Supported Composites
Authors: Majeed Majed A. , Yigit Ahmet S. , Christoforou Andreas P.
Published: February 2011

This paper presents an elastoplastic impact model for a spherical object impacting a supported composite layer or a half-space. The model utilizes a contact law that has been developed based on elastic-plastic and fully plastic indentation theories. For an impact event, the model parameters can easily be obtained analytically, computationally using Finite Elements (FE), and from experiments, by assuming transversely isotropic material behavior. Simulations are compared to those from a nonlinear FE model developed in ABAQUS, and to limited experimental data, with excellent results.
PVDF-HFP-NH4CF3SO3-SiO2 Nanocomposite Polymer Electrolytes for Protonic Electrochemical Cell
Authors: Muda N. , Ibrahim Salmiah , Kamarulzaman Norlida , Nor Sabirin Mohamed
Published: February 2011

This paper describes the preparation and characterization of proton conducting nanocomposite polymer electrolytes based a polyvinylidene fluoride-co-hexapropylene (PVDF-HFP) for protonic electrochemical cells. The electrolytes were characterized by Differential Scanning Calorimetry (DSC) and Impedance Spectroscopy (IS). It is observed that the crystallinity of the PVDF-HFP-NH4CF3SO3 system slightly increase upon addition of SiO2 nanofiller. The PVDF-HFP-NH4CF3SO3-SiO2 electrolytes reveals the existence of two conductivity maxima at 1 and 4 wt% of SiO2 concentration attributed to two percolation thresholds in the nanocomposite polymer electrolyte. The optimum value of conductivity of 1.07 × 10-3 S cm-1 is achieved for the nanocomposite polymer electrolyte film with 1 wt% SiO2. Protonic electrochemical cells was fabricated with a configuration Zn + ZnSO4.7H2O + PTFE (anode) | PVDF-HFP:NH4CF3SO3+SiO2 (electrolyte) | MnO2 + PTFE (cathode). The maximum open circuit voltage (OCV) is ~1.50 V and discharge characteristics of the cell were studied at different loads of resistances.
Li2CO3 – Al2O3 Composite Solid Electrolytes Prepared by Sol Gel Method
Authors: Sulaiman Mazdida , Rahman Azilah Abd , Nor Sabirin Mohamed
Published: February 2011

Composite solid electrolytes in the system (1-x)Li2CO3-xAl2O3, where x = 0.1–0.7 were prepared by sol gel method using lithium carbonate and aluminum oxide precursors in ethanol. The gels obtained due to the addition of citric acid were calcined at 80 and 100 oC. Their structural, thermodynamic and electrical properties were investigated by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and impedance spectroscopy. The results indicated that interface phases of crystalline and amorphous exist in this composite system of (1-x)Li2CO3-xAl2O3. The presence of the interface phases are due to the chemical and physical interactions between both crystalline Li2CO3 and Al2O3. The Arrhenius plot of the composite system showed non-linear curves and reached maximum values of ∼10−4 - 10−5 S cm-1 at 150 -180 °C. Based on the results of this study, it can be concluded that the sol gel method used in the preparation of the composite system, has an important role to crystal morphology changes that results in high ionic conductivity.
Measurement on Strain Rate Sensitivity and Dynamic Mechanical Properties of Various Polymeric Materials
Authors: Omar Mohd Firdaus , Hazizan Md Akil , Ahmad Zainal Arifin
Published: February 2011

Strain rate sensitivity and dynamic mechanical properties of polymeric materials are affected to a certain extent especially by the rate of loading. However, there is limited number of works reported on that particular issue. Therefore, the paper presents on static and dynamic mechanical properties of various polymeric materials across strain rate from 10-2 to 10-3 s-1. The specimen were tested using universal testing machine (UTM) for static loading and a conventional split Hopkinson pressure bar (SHPB) apparatus for dynamic loading. From the results, the compression modulus and compressive strength of all tested specimen increased significantly with increasing strain rates. In addition, positive increment in terms of strain rate sensitivity was recorded for all tested polymers over a wide range of strain rate investigated. Meanwhile, the thermal activation volume has decreased as increasing strain rate. Of the three polymers, polypropylene shows the highest strain rate sensitivity at static region. On the other hand, at dynamic region, polycarbonate shows the highest strain rate sensitivity than that of polypropylene and polyethylene.
Effect of Mg Content on the Characteristics of Al/SiC Nanocomposite Powders Produced via In Situ Powder Metallurgy Method
Authors: Moazami-Goudarzi Mohammad , Akhlaghi Farshad
Published: February 2011

In the present study the effect of Mg addition on the characteristics of Al/SiC nanocomposite powder particles produced via a relatively new method called in situ powder metallurgy (IPM) is investigated. Commercially pure Al and Al-Mg alloy melts containing different amounts of Mg were used as the matrix alloy. Nano-sized SiC particles with the average size of 60 nm were used as the reinforcing material. The effect of Mg content on the fluidity of the melt as an influencing factor affecting both the process yield and wettability of SiC with molten metal was investigated. The size distribution of produced powders was characterized using a laser particle size analyzer. Scanning electron microscopy was utilized to investigate the possibility of embedding of SiC nanoparticles within the metallic matrix. Results of microhardness measurements together with SEM micrographs and EDS analysis showed that nano-sized SiC particles could be embedded in the relatively coarse Al-Mg powders containing at least 1 wt.% Mg.
Comparative Study of Physical Properties Based on Different Parts of Sugar Palm Fibre Reinforced Unsaturated Polyester Composites
Authors: Sahari J. , Sapuan S.M. , Ismarrubie Z.N. , Rahman M.Z.A.
Published: February 2011

This research was conducted to evaluate the potential of sugar palm residue as a raw material to produce the new green composites. The physical properties of sugar palm fibre reinforced unsaturated polyester composites from different part which are sugar palm frond (SPF/PE), sugar palm bunch (SPB/PE), sugar palm trunk (SPT/PE) and black sugar palm fibre (ijuk/PE) were studied. Samples were submerged in distilled water for 24 hours. The water absorption and thickness swelling were investigated in order to determine the dimensional stability of the composites. It is found that SPF/PE showed the higher value of water absorption and thickness swelling which are 1.57%, and 1.56% followed by SPB/PE (1.35%, 1.11%), ijuk/PE (0.65%, 0.76%) and SPT/PE (0.39%, 0.50%). Generally, this investigation is valuable for researchers in order to evaluate the potential and some possible application of sugar palm residues as a new natural composites product.
The Effect of Silane Treatment on Tensile Properties and Morphology of Polypropylene/Recycled Acrylonitrile Butadiene Rubber/Rice Husk Powder Composites
Authors: Ragunathan Santiagoo , Hanafi Ismail , Kamarudin Hussin
Published: February 2011

The effect of silane treatment on tensile properties and morphology of recycled acrylonitrile butadiene rubber(NBRr)/polypropylene(PP)/rice husk powder(RHP) composites has been studied. Polypropylene/recycled acrylonitrile butadiene rubber/rice husk powder (PP/NBRr/RHP) composite were prepared by melt mixing technique at 180º C for 9 minutes and 50rpm rotor speed using an internal mixer. Five different composites compositions (70/30/0, 7030/5, 70/30/10, 70/30/15 and 70/30/30), with silane treated RHP(treated) and without silane treatment(untreated) was studied. The specimens were analyzed by different techniques i.e. tensile test and scanning electron microscopy (SEM). The result obtained showed lower tensile properties with increasing amount of NBRr content. Lower tensile strength and tensile modulus was exhibited with increasing NBRr content. However higher tensile strength, greater tensile modulus and lower elongation at break in PP/NBRr/RHP was exhibited for silane treated RHP composites compare with untreated RHP. PP/NBRr/RHP composite was found to become more brittle with strong attachment between PP/NBR matrix and RHP filler with silane treatment. Good adhesion between silane treated RHP filler and PP/NBRr matrix was confirmed by the morphological studies.