bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Bit Rate Video Coding for Remote Desktop Operation of CNC Milling
Authors: Al Qodri Maarif Haris , Gunawan Teddy Surya , Afzeri
Published: July 2011

Scalable Video Coding (SVC) is the extension of the H.264/AVC standard. The SVC has good capability in video transmission systems because of its scalability which can adapt in different network conditions, especially in low bit rate transmission. The objective of this paper is to develop the low bit rate video coding for assisting the remote operation of Command and Control (CNC) milling process through virtual simulation and remote desktop interface. The algorithm for low bit rate video coding will be in the downsampling of high resolution layer before the encoding process and upsampling the high layer data in the decoder. Based on simulation results, the proposed scheme shows good performance in maintaining the video quality at 128 kbps while providing high time savings for the encoding process.
Finite Element Analysis of Tubular Ovality in Oil Well
Authors: Pervez Tasneem , Qamar Sayyad Zahid
Published: July 2011

This paper presents the finite element analysis of tubular expansion in oval bore holes such as those frequently observed in Upper Natih reservoirs. The minimum inner diameter of the expanded tubular must be larger than the drift diameter set by American Petroleum Institute (API) standards. If the minimum inner diameter is smaller than drift diameter, completion equipments can not be run successfully, which is necessary to complete an oil-well for production. The phenomenon of tubular ovality has been previously unknown to petroleum industry. Finite element model of tubular expansion in oval bore-holes is developed to determine the tubular ovality and compared with measured ovality. It was found that ovality increases linearly with tubular expansion ratio. With increase in expansion ratio, the tubular contact length with formation and developed contact pressure increases. Tubular ovality, if not considered in well design, may lead to premature tubular failure due to lower collapse rating and higher stresses.
Reverse Engineering of Motorcycle Chain
Authors: Maleque M.A. , Rahman M.M. , Hossain M.S.
Published: July 2011

Reverse engineering often involves taking something apart and analyzing its workings in detail to be used in maintenance or to try to make a new product or component that does the same thing without copying anything from the original. In order to understand the existing design, materials and manufacturing process of a motorcycle chain and also for the future direction in new materials with new design, a comprehensive study on the reverse engineering is essential. Therefore, in this paper, a systematic study on a motorcycle chain reverse engineering is performed. The two types of motorcycle chains (Chain A and Chain B) were destructed and investigated using the metallurgical microscope and hardness tester for microstructural and microhardness examination purposes respectively. It was found that the Chain A showed tempered martensite structure (in the case) with higher hardness value compared to Chain B. The cost analysis of the new proposed motorcycle chain is also given in this paper.
Limit Analysis of Lateral Extrusion of Gear-Like Components with Radial Tooth Profile
Authors: Haghighat H. , Bajelan M.
Published: July 2011

Lateral extrusion of gear- like components with radial tooth profile, has been studied in this paper. To analyze the process, the two types of theoretical approaches, i.e. the upper bound technique and the slab method of analysis have been applied and extrusion load values have been estimated. The theoretical results of load values estimated from the above approaches have been compared with theoretical and experimental results that given by a reference. Good agreement has been found among the predicted load values and those obtained from the experimental results.
Fatigue Life Optimization of Steel by Thermomechanical Treatment with the Use of Physical Thermomechanical Simulator
Authors: Džugan Jan , Nový Z. , Sosnová Martina
Published: July 2011

The investigated 34CrNiMo steel is traditionally used for highly loaded components with very high hardenability, fatigue strength and toughness. There were obtained very good experiences with this material, therefore there is no demand for change of the material, but for the material full potential utilization. This goal could be attained by application of thermo-mechanical treatment to the material of interest. There are compared several materials states obtained by conventional thermal treatment with new thermo-mechanically processed states in the current study. Conventionally treated materials exhibit about half tensile strength of the material after the thermomechanical treatment. The material fatigue life is related to tensile strength of the material. Therefore for representative comparison it is useful to compare materials with similar tensile properties, if the advantage of thermomechanical over heat treatment is to be evaluated. Samples of material of similar tensile strength to thermomechanically treated state were prepared by heat treatment. Fatigue tests were performed for traditionally treated samples with thermomechanically treated state and heat treated state. Thermo-mechanically treated state exhibits superior strength and fatigue life in comparison to all other states investigated. There was also performed metallographical investigation of microstructures of compared states providing information on what sort of microstructures were obtained by which treatment, that could be related to mechanical properties. The study presented here shows potential of thermo-mechanical treatment of traditionally used steels.
Taguchi Method for the Determination of Optimised Sintering Parameters of Titanium Alloy Foams
Authors: Ahmad Sufizar , Muhamad Norhamidi , Muchtar Andanastuti , Sahari Jaafar , Jamaludin Khairur Rijal , Ibrahim Mohd Halim Irwan , Nor Nor Hafiez Mohamad
Published: July 2011

Sintering is a key step in the preparation of metal foams. The present work focuses on the sintering effects on the properties of titanium foam prepared using the slurry technique. Sintering affects the density as well as the mechanical properties of the sintered parts. To achieve a high density of the titanium alloy foam, the effects of various parameters including temperature, time profile and composition have to be characterized and optimized. This paper reports the use of the Taguchi method in characterizing and optimizing the sintering process parameters of titanium alloys. The effect of four sintering factors: composition, sintering temperature, heating rate and soaking time to the density has been studied. The titanium slurry was prepared by mixing titanium alloy powder, polyethylene glycol (PEG), methylcellulose and water. Polyurethane (PU) foam was then impregnated into the slurry and dried at room temperature. This was later sintered in a high temperature vacuum furnace. The various factors were assigned to an L9 orthogonal array. From the Analysis of Variance (ANOVA), the sintering temperature was found to give the highest percentage of contribution (34.73) followed by the composition of the titanium alloy powder (26.41) and the heating rate (0.64). The optimum density for the sintered titanium alloy foam was 1.4873±0.918 gcm-1. Confirmatory experiments have produced results that lay within the 90% confidence interval.
Behavior of Mortarless Wall Subjected to In-Plane Combine Loading
Authors: Safiee N.A. , Jaafar M.S. , Noorzaei Jamal
Published: July 2011

The ability of mortarless wall to restrain/sustain lateral load become important aspect to be consider in the design of wall. Therefore, this paper presents analyses of mortarless wall subjected to in-plane combined loading using finite element programs. The developed 2D finite element program is used in this research. The finite element models are developed based on micro modelling approach where each constituent of masonry (block and dry joint) connected each other by joints at their actual position. Eight nodded isoparametric plane element and six nodded zero thickness isoparametric interface element are used to represent block unit and dry joint respectively. The developed models are analysed under nonlinear environment. The most relevant results concern the strength response of the dry joint masonry walls subjected to in-plane combined compressive and shear loading. The results of finite element analysis compared with corresponding experimental results and its show good agreement. Parametric study also performed to consider the important parameters that effect the design of wall under combined loading. Significant features of the structural behaviour, ultimate capacity and observed failure mechanisms are addressed and discussed.
A Heuristic Solution of Multi-Item Single Level Capacitated Dynamic Lot-Sizing Problem with Setup Time
Authors: Parveen Sultana , Akthar Hasin Md. Ahsan
Published: July 2011

The multi-item single level capacitated dynamic lot-sizing problem consists of scheduling N items over a horizon of T periods. The objective is to minimize the sum of setup and inventory holding costs over the horizon subject to a constraint on total capacity in each period. No backlogging is allowed. Only one machine is available with a fixed capacity in each period. In case of a single item production, an optimal solution algorithm exists. But for multi-item problems, optimal solution algorithms are not available. It has been proved that even the two-item problem with constant capacity is NP-hard, that is, it is in a class of problems that are extremely difficult to solve in a reasonable amount of time. This has called for searching good heuristic solutions. For a multi-item problem, it would be more realistic to consider the setup time, since switching the machine from one item to another would require a setup time. This setup time would be independent of item sequences and this could be a very important parameter from practical point of view. The current research work has been directed toward the development of a model for multiitem problem considering this parameter. Based on the model a program has been executed and feasible solutions with some real life data have been obtained.
Statistical Wear Model for Adhesively Bonded Tools
Authors: Darwish S.M. , Al Samhan Ali M. , Helmy H.A.
Published: July 2011

Computerized machinability data systems are essential for the selection of optimum conditions during process planning, and they form an important component in the implementation of computer integrated manufacturing (CIM) systems. Since statistical models for adhesively bonded tools are unavailable, the present paper presents a study of the development of a tool life, surface roughness and cutting force models for turning constructional steels, using adhesively bonded tools. These models are developed in terms of cutting speed, federate and depth of cut. These variables are investigated using design of experiments and utilization of response surface methodology (RMS).
Sintering of Hydroxyapatite Ceramic Produced by Wet Chemical Method
Authors: Singh Ramesh , Tolouei R. , Tan Chou Yong , Aw K.L. , Yeo Wei Hong , Sopyan Iis , Teng Wan Dung
Published: July 2011

In the present work, densification of synthesised hydroxyapatite (HA) bioceramic prepared via chemical precipitation method was investigated. HA samples was prepared by compaction at 200 MPa and sintered at temperatures ranging from 800°C to 1400°C. The results revealed that the HA phase was stable for up to sintering temperature of 1250°C. However, decomposition of HA was observed in samples sintered at 1300°C with the formation of tetra-calcium phosphate (TTCP) and CaO. Samples sintered above 1400°C were found to melt into glassy phases. The bulk density increases with increasing temperature and attained a maximum value of 3.14 gcm-3 at 1150°C whereas maximum hardness value of 6.64 GPa was measured in HA sintered at 1050°C. These results are discussed in terms of the role of grain size.
Laser Cutting of Thick Sheet Metal: Surface Plasma Characteristics and Cutting Quality Assessment
Authors: Yilbas Bekir Sami
Published: July 2011

The quality laser cutting of thick sheet metals is demanding due to requirements of high precision, lost cost, and short processing time. However, the surface plasma is formed during the cutting process to influence the end product quality. The surface plasma is transiently hot and lowers the resulting cutting quality via increasing thermal erosions from the cut edge edges. In the present study, the surface plasma characteristics are examined using the Langmuir probe. Electron temperature and electron number density are determined in the surface plasma. The cutting quality is, then, related to the plasma characteristics. Scanning Electron Microscopy (SEM) is carried out to examine the microstructural changes at the cut edges. It is found that cutting quality improves at a particular assisting gas pressure; in which case, the influence of surface plasma on the cutting process becomes the minimum.
An Investigation on the Effect of Sonication Time and Dispersing Medium on the Mechanical Properties of MWCNT/Epoxy Nanocomposites
Authors: Montazeri Arash , Khavandi Alireza , Javadpour Jafar , Tcharkhtchi Abbas
Published: July 2011

This work studied the effect of sonication time and dispersing medium on the dispersion state of 0.1%wt multi-wall carbon nanotube (MWCNT) in the MWCNT/epoxy nanocomposite system. Epoxy, hardener, and epoxy/solvent were used as dispersing mediums in this study. Tensile strength, strain at failure, Young's modulus and fracture toughness were measured under different dispersion state of MWCNT. The results indicate that with the increase in sonication time, initially there was an increase in tensile strength and fracture toughness values which was followed by a drop in values at longer sonication times. The highest Young's modulus values were seen in epoxy dispersion and the highest tensile strength and fracture toughness values were observed when the hardener was used as dispersing medium. The results also indicated that the effect of sonication time was more pronounced in the case of epoxy dispersion. The effect of time was least when the epoxy / solvent system was used as CNT dispersing medium. It should also be pointed out that the Young's modulus for the nanocomposite sample obtained after 1h of dispersion in hardener showed good agreement with a modified Halpin-Tsai theory. The scanning electron microscope (SEM) was used to characterize the dispersion state of MWCNT. A good dispersion was obtained when either hardener or solvent were selected as the dispersing medium.
Response Surface Analysis of EDMED Surfaces of AISI D2 Steel
Authors: Pradhan Mohan Kumar , Biswas Chandan Kumar
Published: July 2011

In this study, the effects of the machining parameters in electrical-discharge machining (EDM) on the machining characteristics of AISI D2 steel using copper electrodes were investigated. The response functions considered material removal rate (MRR) and Surface Roughness (Ra),while machining variables are pulse current, pulse on time, pause time and gap voltage. A Response surface methodology was used to reduce the total number of experiments. Empirical models correlating process variables and their interactions with the said response functions have been established. The significant parameters that critically influenced the machining characteristics were examined, and the optimal combination levels of machining parameters for material removal rate, and surface roughness were determined. The models developed reveal that pulse current is the most significant machining parameter on the response functions followed by voltage and pulse off time for MRR. However for, for Ra also pulse current is most significant followed by pulse on time and discharge voltage the respectively. The model sufficiency is very satisfactory as the coefficientR2of is determination (R2) is found to these be greater than 98 %. These models can be used for selecting the values of process variables to get the desired
Sn-Rich Phase Coarsening in Sn-Ag-Cu Solder Joint during Moderate Current Stressing
Authors: Saud N. , Jalar Azman
Published: July 2011

The changes of microstructure in eutectic sn-3.8ag-0.7cu during moderate current stressing have been investigated. The current stressing values were 102 and 103 a/cm2. The tests were carried out for 24, 216, 576 and 1008 hours. Sn-rich phases and eutectic phases appear immediately after soldering process. However, thermal rise during current stressing has coarsened sn-rich phases and altered the microstructure of the solder. Higher current density leads to larger snrich phase coarsening. The microstructures for current stressing test were also compared with the series of microstructure for isothermal annealing test since there is similarity in coarsening effect for both tests. The effect of thermal rising during current stressing as well as during isothermal annealing to sn-rich phase coarsening is established and will be discussed further.
Temperature Distribution of Aluminum Alloys under Friction Stir Welding
Authors: Lin Ben Yuan , Yuan P. , Liu Ju Jen
Published: July 2011

The temperature distribution of 6061-T6 aluminum alloy plates under a friction stir butt-welding was investigated by using experiment and numerical simulation. A real-time temperature measuring system was used to measure the temperature change in the welding process. Vickers hardness profiles were made on the cross-section of the weld after welding. A commercial software of FlexPDE, a solver for partial different equations with finite element method, was used to simulate the experimental welding process of this study. Comparison the experimental and numerical results, the temperature cycles calculated by numerical are similar to those measured by experiment. The temperature distribution profile obtained from the numerical simulation is symmetrical to the weld center and has a close correspondence with the hardness configuration and the microstructure of the weld. The region with the temperature over 300 °C is the zone of softening within the boundaries of base material and HAZ. The regions of 350 °C with minimum hardness are located near the boundary of HAZ and TMAZ. The maxima temperature about 500 °C distributes around the upper part of the weld center. However, the region above 400 °C only matches with the upper half of the weld nugget.
Investigation of Joint Groove Geometry Effect on the Residual Stresses in Circumferentially Butt-Welded Steel Pipes by the FEM Simulation
Authors: Foroutan M. , Aalami-Aleagha M.E. , Pirmoradi S.
Published: July 2011

In this paper effect of joint groove geometry on the residual stresses in circumferentially butt-welded still pipes is investigated by the finite element simulation. The elements birth and death technique is used for modeling of filling metal and joint groove geometry. The electrode heat power is modeled by a moving heat source which has a Gaussian distribution on a spherical domain. By using a transient region, elements near the welding zone are refined in a good manner. For validation of the proposed model, results obtained from model are compared with experimental data. Then three different joint geometry; V-joint, U-joint and X-joint are studied by the presented model.
A Comparison between Isothermal and Coupled Thermo-Mechanical FE Analyses of the Ring Rolling Process
Authors: Anjami Nassir , Basti Ali
Published: July 2011

Ring rolling process, especially hot rolling is characterized by 3D deformation, continuous change of thickness and height, high nonlinearity, non-steady flow and asymmetry. It involves both mechanical and thermal behaviors. Most mechanical and physical properties and boundary conditions are temperature related. The heat flow and stress analysis cannot be analyzed separately. In this study, both isothermal and coupled thermo-mechanical (CTM) 3D rigid-plastic finite element (FE) models of the hot ring rolling (HRR) process are developed to investigate their differences in accurately and quickly predicting the process. The results show that the latter should be more advantageous to the more accurate prediction and control of microstructure and properties of the ring.
Numerical Study of the Flow Forming Process of AISI 630 Stainless Steel
Authors: Ebrahimi Seyed Mohammad , Akbari Mousavi Seyed Ali Asghar , Bayazidi Mostafa Soltan , Mastoori Mohammad
Published: July 2011

Flow forming is one of the cold forming process which is used for hollow symmetrical shapes. In this paper, the forward flow forming process is simulated using the finite element method and its results are compared with the experimental process. The variation of thickness of the sample is examined by the ultrasonic tests for the five locations of the tubes. To simulate the process, the ABAQUS explicit is used. The effects of flow forming variables such as the angle of rollers and rate of feeding of rollers, on the external variables such as internal diameter, thickness of tube and roller forces are considered. The study showed that the roller force and surface defects were reduced with low feeding rate and low rollers attack angles. Moreover, the sample internal diameter increased at low feeding rate and low rollers attack angles. The optimum variables for flow forming process were also obtained.
Design and Simulation on Cast Metal Matrix Composite by Investment Casting
Authors: Taufik  , Sulaiman Shamsuddin , Abdullah T.A. , Sivarao
Published: July 2011

Metal Matrix Composite (MMC) is produced normally by melting the matrix material in a vessel and the molten metal is stirred systematically to form a vortex, and then the reinforcement particles are introduced through the side of vortex formed. However, this approach has disadvantages, mainly arising from the particle addition and the stirring method. There is certainly local solidification of the melt induced by the particles during particle addition. This condition increases the viscosity of the slurry and appears as air pockets between the particles. Moreover, the rate of particle addition needs to be slowed down particularly when the volume fraction of the particles to used increases. This study proposes the new methodology of producing cast MMC by investment casting. Deformations of the die-wax and shell alloy systems are considered in a coupled manner, but the coupled deformation of the wax-shell system is not included. Therefore, this study presents the tasks pertaining to metal matrix composites and their interactions. As a result, the work on wax and wax-die interactions is discussed. This study presents the use of computer programs for determining the wax pattern dimensions based on three-dimensional finite-element simulations. The model for coupled thermal and mechanical analysis is developed by ProCAST. The wax model is described. The following factors are considered in the analysis: (1) the restraint due to geometrical features in the metal die; and (2) process parameters such as dwell time, die/platen temperature, injection pressure, and injection temperature.
Residual Stress; the Effect of Pouring Temperature and Chemical Composition
Authors: Norouzi Saeid , Farhangi Hassan
Published: July 2011

In this research, the effects of two variables, pouring temperature and chemical composition, on residual stress/strain have been studied. The residual strain was experimentally measured using the cutting technique and compared for several alloys; carbon steel, stainless steel, Ni-base superalloy, and cast iron. The thermo-elasto-plastic model was used to model the thermal stress distribution during casting and to predict the residual stress from point to point in rectangularshaped steel castings. Simulation results show that stress distribution is related to the thermal gradients throughout the castings, and maximum residual stress is developed at location which solidifies at the later freezing stages. In addition, the results of experimental measurements are applied to evaluate the effect of pouring temperature and chemical composition on residual stress and distortions in shaped castings.
Influence of Process Parameters on Welding Quality during Lap Welding of Aluminum Sheets Using High Brightness Disk Laser
Authors: Kim Cheol Hee , Ahn Do Chang
Published: July 2011

In laser welding, the heat input per unit length is determined by the welding speed and the laser output power. Along with these parameters, there are several other important parameters such as the shielding gas composition, shielding gas flow rate, beam angle, defocusing distance, and so forth. In this paper, the effect of each process parameter on the welding quality was investigated to establish a laser lap welding process for Al sheets. Al 5J32 and Al 6K32 sheets were used as the base metal, and a 4kW disk laser was used as a high brightness laser power source. The bead appearance, the cross-sectional bead shape, X-ray images, and the weight of spatters were examined to evaluate the welding quality.
Structural Integrity of Spot-Welds Used for Auto-Body Fabrication
Authors: Ray Kalyan Kumar , Mukhopadhyay G.
Published: July 2011

The effects of weld nugget size, base metal strength, mode of loading and pre-strain of base metal on the load bearing capacity of spot-welds have been investigated using two varieties of interstitial free steel sheets. The effect of bake hardening treatment after spot-welding of prestrained sheets has also been examined using an ultra low carbon bake hardening grade steel. The major results infer that: (i) the load bearing capacity of spot-welds increases with increasing nugget size and base metal strength, (ii) the load bearing capacity of spot-welds increases with increasing pre-strain of base metal, (iii) the remnant dislocation density around the spot-weld increases with increasing pre-strain, (iv) the strength of spot-welds on pre-strained sheets does not alter significantly after the baking treatment, but baking treatment increases the strength of pre-strained base metals, and (v) the location of failure is commonly at the interface of HAZ/base metal for tensile-shear specimens and at the HAZ for cross-tension specimens.
An Investigation on Warpage Analysis in Plastic Injection Moulding
Authors: Saifullah Abul B.M. , Masood Syed H.
Published: July 2011

In an injection moulded part, warpage is the distortion caused by non-uniform shrinkage within the plastic part. When looking critically at the causes of warpage, it is found that several key parameters of the moulding process have some effect on the warpage. However, the two major categories that contribute to warpage include the part design and the mould design. In mould design, the gate location, runner/gate system and cooling system design are the major factors affecting not only the warpage and part quality but also the injection moulding cycle time. This paper presents an investigation of using different cooling system configuration on warpage and shrinkage of an industrial plastic part with the aim of determining which cooling configuration will provide minimum warpage and cycle time. As conventional injection mould cooling design is based on straight drilling, it limits the geometric complexity of the cooling design, especially curved shape cooling channels. Nowadays, new technology of advanced rapid tooling based on solid freeform fabrications can be been used to provide conformal cooling channels in injection moulds. In this paper, several type of cooling channels are analysed to compare the performance in terms of warpage and shrinkage and to determine which configuration is suitable for minimizing warpage. Autodesk Moldflow Insight (AMI) simulation software is applied to examine the results of the cooling performances and warpage analysis.
Impact Strength of Carbon Reinforced Epoxy Composite at Different Temperatures
Authors: Lenda T.A. , Mridha S.
Published: July 2011

Charpy impact tests were conducted on carbon reinforced epoxy composites fabricated by hand lay-up method using 0.47, 0.56 and 0.66 carbon fiber volume fractions; tests were conducted at temperatures between -60oC to 60oC. The impact strength was found, in general, to increase when the samples were fractured at temperatures above 0oC and the impact strength decreased with the increase of fiber content. The impact energy absorption was highest of 270 KJm-2 with 47 vol% fiber when fractured at +60oC and it reduced to 130 KJm-2 at -60oC. With decreasing the fracture temperature and increasing the fiber content the impact strength reduced significantly. The reduction of impact energy was from 235 KJm-2 to 107 KJm-2 for 56 vol% fiber and from 196 KJm-2 to 90 KJm-2 for 66 vol% fiber when fractured at +60oC and -60oC, respectively. Failure occurred mostly by fiber delamination; fiber splitting and matrix cracking were also present. Delamination was more in specimens tested at -60oC while fiber splitting and matrix cracking were more when fractured at +60oC.
Preparation of Epoxy-Kenaf Nanocomposite Based on Montmorillonite
Authors: Zuliahani A. , Rozman H.D. , Tay G.S.
Published: July 2011

In the present study, lignocellulosic-epoxy composites were prepared from Kenaf bast fiber at different loadings using resin infusion method. Montmorillonite (MMT) was used as a filler which would be mixed in the epoxy resin before the mixture (resin, hardener and MMT) was infused to the Kenaf fiber mat. The effect of modification on MMT was also studied in this work. MMT was modified using grafting process, which the oxygen in MMT were grafted with isocyanates group from Hexamethylene Diisocyanate (HMDI). The mechanical properties of the composites prepared were improved as Kenaf fiber loadings increased. This indicated that the reinforcement effect by additional of Kenaf fiber was evident. The mechanical properties of the composite can be further enhanced by additional of MMT or HMDI-MMT.
Preparation and Microstructure of Nanocomposite Mg-3Al-Zn Alloy by HDDR Combined with Ball Milling
Authors: Sun Hong Fei , Fang Wa , Yu Zhen Xing , Fang Wen Bin
Published: July 2011

Nanocrystallite Mg-3Al-Zn alloy was synthesized by ball milling of elemental powders of Mg, Al and Zn under hydrogen atmosphere. The powders of Mg, Al and Zn were mechanical alloying and disproportionated by ball milling under hydrogen and desorption-recombination was then performed. The structural changes due to both the milling in hydrogen and the subsequent desorption-recombination treatment were characterized by X-ray diffraction (XRD). The desorption–recombination behavior of the hydrogenation alloy was investigated by differential scanning calorimetry (DSC). The morphology and microstructure of the final alloy powders subject to desorption–recombination treatment were observed by TEM and HRTEM, respectively. The results showed that, by milling in hydrogen for 60 h, the Mg-3Al-Zn alloy was disproportionated into nano-structured with average size of about 60-70 nm, and a subsequent desorption–recombination treatment at 320°C for 30 min alloy didn’t vary the average crystallite size of powders.
Influences and Properties of Various Activated Carbon and Carbon Black Filled in Epoxy Composite
Authors: Firoozian P. , Abdul Khalil H.P.S. , Hazizan Md Akil , Noor Ahmad Md.
Published: July 2011

This paper reports the investigation on the flexural properties of activated carbon filled epoxy composites. The Comparison of the properties between different sources of activated carbon, are illustrated. It has to be disposed safely or used for recovery of valuable materials as agricultural wastes like bamboo stem, coconut shell and Empty Fruit Bunch (EFB). Therefore these wastes have been explored for the preparation of activated carbon and carbon black employing chemical activation by H3PO4 and physical activation, respectively. The effect of pyrolysis and chemical activation on the activated carbon filled epoxy composite properties including mechanical (flexural strength), 5 % percent of carbon filler and Scan Electron Microscope SEM micrograph were analyzed. These determined the interaction between activated carbon filled epoxy composite. This study is to compare the effect of the nature of the different types of fillers on the epoxy composites material properties. The microstructures of the farcture surface was examined using a scanning electron microscope (SEM) were formed during the different preparation stages.
Synthesis and Characterization of TTAB Coated Silver (Ag) Nanoparticles
Authors: Alam M.M. , Harun M. , Islam Momtazul
Published: July 2011

Silver nanoparticles protected by Tetradecyltrimethyl Ammonium Bromide (TTAB) were prepared in a one-phase electrochemical system. Electrochemical procedure, based on the dissolution of a metallic anode in an appropriate solvent, has been used to get silver nanoparticles. It is possible to get different particle size by changing the current density. The optical properties of the silver Nanoparticles were investigated by UV-Vis and Photoluminescence (PL) Spectroscopy. Absorption peak were found 424 nm which confirm the presence of Ag nanoparticles. The structural properties of the samples were carried out by scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements. XRD confirmed the preferential growth of Ag nanoparticles whose average size is ≈ 20 nm in the <111> orientation as well as purity of silver clusters.
Mathematical Modeling of Flow Behaviour of API-X70 during Hot Torsion Testing
Authors: Mirzakhani Bahman
Published: July 2011

The flow behaviour of material is strongly influenced by the microstructure evolution during hot deformation processes. In this work, a comprehensive mathematical modelling of heat transfer and plastic deformation was carried out employing finite element analysis based on rigidviscoplastic formulation. Semi-empirical models of dynamic recovery and recrystallization were utilized to develop the microstructure dependent constitutive equations. They were then integrated into the finite element code to simulate stress-strain curve of API-X70 steel during hot deformation process. Hot torsion tests were carried out at various deformation conditions for characterization of microstructure equations and model validation. The good agreement between experimental data and simulation results were achieved. The model predicts work hardening, dynamic recovery and recrystallization simultaneously and it considers their effects on the flow stress of the material during hot deformation.
Effects of Polymer Loading on Tropical Wood Polymer Composite (WPC)
Authors: Islam M. Saiful , Hamdan Sinin , Rahman Md. Rezaur
Published: July 2011

Batai (paraserianthes moluccana) tropical wood species was impregnated with three levels of polyvinyl alcohol (PVA) solutions (25%, 50% and 75%) for composite manufacturing. Manufactured wood polymer composites (WPCs) were characterized using Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), free-free vibration testing, and the dimensional stability analysis. The dynamic Young’s modulus (Ed) was calculated using the free-free flexural vibration method. Impregnation of PVA solutions into wood samples was confirmed through FTIR and SEM. WPC from 75% PVA solution showed lower water absorption and improved dimensional stability. The fabricated WPC yielded a higher Young’s modulus compared with the raw one.
Coefficient of Thermal Expansion Measurement of Metal Matrix Composites by Thermo Mechanical Analyser
Authors: Karthikeyan B. , Ramanathan S. , Ramakrishnan V.
Published: July 2011

The demand of today’s and future spacecrafts for a stable platform for critical payloads is the driving force behind the coefficient of thermal expansion (CTE) measurement of different aerospace materials. The CTE of a composite is different from that given by a simple rule of mixtures. This is because of the presence of reinforcement. The expansion coefficient of reinforcement is less than that of the matrix which introduces a mechanical constraint on the matrix. The degree of constraint is also dependent on the nature of the reinforcement. It is important to point out that interface can exert some influence on the value of CTE, especially for very small particle size. In addition to the interface, the CTE of particle reinforced metal matrix composites (MMCs) is affected by several other factors. To cater the needs of various requirements in a spacecraft making, a wide variety of materials are used. Besides, the indigenization efforts and development of new materials for space-use emphasizes the measurement of CTE before their actual use. Stir casting technique was used to fabricate composites containing Si Cp as reinforcements and special thermo physical properties of the material are found. CTE of the composites are measured by TMA. The experiments have been carried out in the temperature range -1400 C to 5750 C.
Two-Dimensional Stresses in a Hollow FG Sphere with Heat Source
Authors: Mohazzab Amir Hossein , Jabbari Mohsen
Published: July 2011

This work studied the theoretical solution for axisymmetric steady-state mechanical and thermal stresses in hollow functionally graded spheres with respect to heat source. The material properties of the FG sphere change continuously across the thickness direction according to the power functions of radial direction. The steady-state temperature, displacements, and stresses are derived due to the general mechanical and thermal boundary conditions as function of radial and circumferential directions. The temperature and Navier equations are solved analytically, using Taylor and Legendre series. With increasing the power law indices the temperature distribution due to heat source is decreased. Circumferential stress and radial displacement due to heat source are decreased as the power law index increases.
Ultra-Violet Radiationcured Composites Based on Unsaturated Polyester Resin Filled with MMT and Kenaf Bast Fiber
Authors: Rozyanty A.R. , Rozman H.D. , Tay G.S.
Published: July 2011

In this study, nanocomposites based on unsaturated polyester cured by ultra-violet (UV) radiation were prepared using Kenaf bast fibre and Montmorillonite (MMT) as reinforcing agent at different percentages. MMT was modified using an ion exchange process by replacing the sodium ions with alkyl ammonium ions from Cetyltrimethylammonium Bromide (CTAB). From the results obtained, the microstructure of MMT modified with CTAB (MMT-CTAB) showed the interlayer spacing of MMT-CTAB was increased and X-ray diffraction analysis indicated that cation exchange between CTAB and MMT was evident. As for the composites prepared from untreated MMT-CTAB, it showed higher mechanical properties as compared to those prepared from untreated MMT. On the other hand, the percentage of Kenaf fiber in the nanocomposites system also plays a crucial role in determining the nanocamposites properties.
Nano Crystalline La Substituted Barium Hexaferrite Synthesized by Coprecipitation Method
Authors: Ataie Abolghasem , Moslemi S.
Published: July 2011

La substituted barium hexaferrite Ba1-yFe12LayO19 with 0≤ y ≤0.5 was synthesized by chemical co-precipitation method using aqueous solutions of metallic chlorides at ambient temperature. NaOH was used as a precipitant. The co-precipitated products were annealed at 900 and 1000°C. The effects of La addition on the phase composition, morphology and thermal behavior of samples were studied using XRD, SEM and DTA/TGA, respectively. XRD results indicated that barium hexaferrite forms together with some intermediate phases in samples annealed at 900°C and the amount of intermediate phases decreased significantly by increasing annealing temperature to 1000°C. XRD results also showed that in sample annealed at 1000°C, the crystallite size of magnetic phase decreases from 98 to 64 nm by increasing the amount of La. Thermal analysis (DTA/TGA) implies that formation temperature of barium hexaferrite is increased with addition of La.
Temperature Effects on the Preparation of Multi-Walled Carbon Nanotubes by Floating Catalytic Chemical Vapor Deposition
Authors: Cheng Jin , Zou Xiao Ping
Published: July 2011

In this study, we report the synthesis of carbon nanotubes by floating catalytic chemical vapor deposition, which employs ferrocene as the catalyst precursors and ethanol as carbon source. We obtained massive deposits. The deposits were characterized by scanning electron microscopy, transmission electron microscopy, and visual laser Raman spectroscopy. We discussed the effects of synthesis temperature on the synthesis of carbon nanotubes by floating catalytic chemical vapor deposition. Our results indicated that the synthesis temperature could affect not only on the graphitization degree, but also on the aligned growth of carbon nanotubes and the diameter of carbon nanotubes.
Characterizing Chicken Eggshell Reinforced Polypropylene (PP)
Authors: Sivarao  , Salleh Mohd Rizal , Kamely A. , Tajul A. , Taufik
Published: July 2011

Chicken eggshell (ES) is an industrial by product containing 95% calcium carbonate and its disposal constitutes a serious environmental hazard. ES contains about 95% calcium carbonate in the form of calcite and 5% organic materials such as type X collagen, sulfated polysaccharides, and other proteins. Although there have been several attempts to use eggshell components for different applications, its chemical composition and availability makes eggshell a potential source of filler for PP composites. In this research work, different proportions of chicken eggshell as bio-filler for polypropylene (PP) composite were compared with different operating temperature by creep test, hardness test and SEM photomicrographs. The eggshell had been prepared by blending and sieving them into granule size of less than 160μm. The granules were then mixed with polypropylene into four weight ratios, 10%, 20%, 30% and 40% respectively using fine extruder, where silane was used as the coupling agent. From the result, it was learnt that, the ES filler had improved Creep Strain and Creep Modulus for the operating temperatures of 34°C and 80°C. Tensile and flexural tests were also performed to study the pattern and behaviour of the chicken egg shell particulated polypropylene. In general, the findings can be concluded that not all ratios of particulation yielded positive as expected, but there were also conditions where virgin polypropylene yields better result depending on the test type and composite matrices.
Effect of Hot Rolling Deformation on Superplastic Deformation Behavior of TiNP/2014Al Composite
Authors: Hu Hui E , Zhen Liang
Published: July 2011

1.5 mm, 0.7 mm and 0.3 mm thicknesses TiNP/2014Al composite sheets were obtained by hot rolling deformation carried out on as-extruded TiNP/2014Al composite rod. The effect of hot rolling deformation on high strain rate superplastic deformation behavior of the composite was researched by tensile experiment, OM, and SEM. Results show that 0.7mm thickness TiNP/2014Al composite sheet can gain the maximum elongation of 351% at 818 K and 3.3×10-1 s-1, and the m value is 0.43. The optimum strain rate increases with decreasing thickness of the TiNP/2014Al composite sheets. Flow stress and work hardening ability show contrary change tendency to optimum strain rate. The 0.7 mm thickness TiNP/2014Al composite sheet has medium flow resistance stress and shows excellent stability of plastic flow. Fracture surfaces show that the main superplastic deformation mechanism of the TiNP/2014Al composite includes in grain boundary sliding. Subgrain boundary sliding maybe another superplastic deformation mechanism.
Application of Ductile Fracture Criteria to Industrial Cutting Processes
Authors: Petruška Jindrich , Borkovec Jan , Hulka Jiri , Foret Rudolf
Published: July 2011

Experimental and numerical studies of fracture prediction with Czech steel no.41 2050 are presented. Seven ductile fracture criteria were calibrated, applied to simulation of rod cutting and bolt head trimming operation and compared with experimental results of these processes, obtained in semi-industrial conditions in cooperation with our industrial partner. Movement of the cutting tool was stopped in predefined positions, so that a step-by-step mapping of subsequent stages of both processes were obtained at different specimens. By metallographic analysis of these, full view of plastic deformation and damage in the vicinity of the cutting region could be seen, and their comparison with the computational results was done.
Analysis of the Machinability of Aluminium Alloys UNS A97050-T7 and UNS A92024-T3 during Short Dry Turning Tests
Authors: de Agustina B. , Saa A. , Marcos Bárcena Mariano , Rubio E.M.
Published: July 2011

The aluminium alloys are widely employed in the aeronautical, aerospace and automotive industries in the most important manufacturing processes. This is due to the fact they have a high resistance even at high temperatures as well as a low density. Nevertheless, these materials can commonly show problems associated with the heat generated during the machining process that reduces their machinability. For this reason, cutting fluids are still widely used. However, the growing social preoccupation towards environmental conservation has made it necessary to develop cleaner production technologies as dry machining, in which no cutting fluids are employed. This situation makes necessary to look for combinations of cutting parameters and types of tools that improve the machining in those extreme work. In this study, the UNS A97050-T7 and UNS A92024-T3 aluminium alloys were analyzed in terms of surface roughness and the morphology of chips obtained, using tools with TiN coating. It was found that the surface quality of the aluminium UNS A97050-T7 and UNS A92024-T3 bars improves with the descent of the feed and with the increase of the cutting speed, being the feed the cutting parameter more influential on the surface roughness. Thus the machining of the UNS A92024-T3 allows obtaining shorter chips than the UNS A97050-T7.
Analysis of the Vitrified CBN Wheels for the Performance of Grinding Hardened Steel
Authors: Luo S.Y. , Wu S.Q. , Hsu F.J.
Published: July 2011

This paper investigates the effect of the CBN abrasive types, sizes, concentration, bond amount, and porosity of a vitrified-bonded CBN wheel on grinding ratio, grinding forces, and surface roughness of grinding hardened steels. The experiment results showed that during grinding hardened steels the amount of bond with increase of the depth of cut increased, which makes the wheel to have a better bonding strength to get a better grinding ratio and surface roughness of the workpiece. The grinding forces produced increased with the increase of the depth of cut. In addition, too much porosity of a vitrified CBN wheel will cause the low bond strength, leading the wheel to wear rapidly. Hence, to obtain a higher grinding ratio and better surface roughness of the workpiece during the grinding hardened steels should select relatively a higher amount of bond, a lower porosity, and a higher grit strength and concentration, but the grinding forces produced were relative higher.
Tensile and Dynamic Mechanical Behavior of Thermoplastic Natural Rubber (TPNR) Nanocomposites Treated with Ultrasonic
Authors: Tarawneh Mou'ad A. , Ahmad Sahrim Hj. , Yahya S.Y. , Rashid Rozaidi
Published: July 2011

Melt compounding technique was employed to prepare thermoplastic natural rubber (TPNR) nanocomposite. The ultrasonic bath was used to improve the filler-matrix interfacial adhesion. TPNR nanocomposites were prepared in the ratio of (70:20:10) from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer, with 4% NanolinDK4. The clay layers were found to be separated further with ultrasonic treatment as compared to the sample without ultrasonic treatment as exhibited from X-ray diffraction. Young's modulus, tensile strength and elongation at break of TPNR nanocomposites increased with ultrasonic treatment, the optimum results achieved at 3h. .The results obtained from dynamic mechanical analysis (DMA) curves indicate that the addition of MWNTs led to an increase in the storage modulus E' and loss modulus E'' with maximum value is obtained at 3 hours. The glass transition temperature (Tg) also increases with Ultrasonic treatment. Ultrasonic treatment can promote the dispersion of the clay in TPNR also improve the compatibility of organoclay filler and the TPNR matrix.