bluuebunny/crossref_metadata_2025 huggingface dataset:
Wear Behavior of Al/SiC Composite Coatings According to Sliding Speed and Applied Load
Authors: Lee Jae Hong , Kim Kyun Tak , Kim Yeong Sik
Published: February 2012

Thermal spray technology allows providing wear-resistant coating on the surface of mechanical components. In this study, wear characteristics of thermally sprayed Al/SiC composite coatings were evaluated. These Al/SiC composite coatings reinforced with SiC particles were fabricated on Al 6061 substrate by thermal spray process. Dry sliding wear tests were performed using the varied sliding speeds and applied loads. Wear behavior of these Al/SiC composite coatings were investigated using scanning electron microscope(SEM), energy dispersive X-ray spectroscopy(EDX) and X-ray diffraction(XRD).
Effect of Thermo-Oxidative Ageing on Aviation Polysulfide Sealants
Authors: Wang Yun Ying , Meng Jiang Yan
Published: February 2012

Aviation polysulfide sealants have been subjected to thermo-oxidative ageing. Their morphologies, Shore A hardness, and tensile properties have been tested by means of an optical microscope, a glossiness meter, a Shore A hardness meter, and a universal testing machine. Changes in their microstructures were measured by Fourier-transform infrared spectroscopy and dynamic mechanical analysis (DMA). The results showed that glossiness was gradually reduced, and bubbles appeared on the surface of the samples during the course of ageing. The Shore A hardness of the sealant first decreased and then remained unchanged. Likewise, the tensile strength and tensile elongation percent first decreased and then remained unchanged. The infrared monitoring showed that the sealant underwent a post-cure reaction. The glass transition temperature and the room-temperature storage modulus of the sealant remained unchanged. No new functional groups were formed during ageing of the sealant. The aviation sealants did not undergo chemical degradation, showing that they have good endurance under thermo-oxidative conditions.
Synthesis of 2-Acetoxy-6-Naphthoic Acid with P-Methylbenzenesulfonic Acid as Catalyst
Authors: Song Yuan Jun , Li Yan Wei , Pan Bao Qing , Song Hao Nan
Published: February 2012

2-acetoxy-6-naphthoic acid (ANA) was synthesized in the presence of 2-hydroxy -6-naphthoic acid (HNA) and acetic anhydride (CH3CO)2O with toluenesulfonic acid (PTSA) as catalyst. The effects of reactant ratio, temperature, time were investigated in the acetylation process. 1H-NMR、13C-NMR、FT-IR、HPLC measurements indicate the optimal acetylation reaction condition when the ratio of HNA: (CH3CO)2O : PTSA are 1: 2.3:0.025 under the temperature at 90~95°C for 40min.
Microstructures and Properties of Hypoeutectic Al-Si Alloy Extruded in Semi-Solid State
Authors: Zhao Da Zhi , Yu Fu Xiao , Liu Fang , He Ke Zhun , Zuo Liang
Published: February 2012

The microstructures and properties of AlSi7Mg alloy extruded at 575°C in semi-solid state were studied for analyzing the extruding feasibility of the casting aluminum alloy in high solid fraction. The results show that the microstructure of AlSi7Mg alloy through low-superheat direct chill (DC) casting mainly consists of the homogeneous, fine rosette-shaped grains. The microstructure of the billet reheated at 575°C in 15min is composed of stable and near- spherical grains, which are suitable for thixoforming in high solid fraction. Extruded at 575°C in the semi-solid state, the facial-smoothed parts of AlSi7Mg alloy with homogeneous, fine microstructure across the section is obtained, and the properties of extruded part are improved obviously.
Reliability Evolution of Optical Fibre Subjected to Chemical Environment
Authors: Severin Irina , El Abdi Rochdi , Poulain Marcel , Caramihai Mihai
Published: February 2012

The increased optical fiber development for a variety of physical and chemical measurements using smart structures and sensors leads to investigate the mechanical and chemical reliability of standard commercial acrylate polymer coated fibers. A comparison of mean failure strength of as-aged fibres to the water influence for similar exposure duration has revealed the highest sensitivity to dimethyl sulfoxide reagent (DMSO). SEM investigation revealed different damage levels in function of the aging conditions.
Design Criteria of a DMFC Stack with Low Scaling Effects
Authors: Shakeri Mohsen , Imen Javad , Delavar A.
Published: February 2012

In this paper, recent advances in design and fabrication of a direct methanol fuel cell (DMFC) stack are presented. DMFC fuel cells are viewed as one of the most environmentally friendly energy conversion system due to high theoretical electrical efficiency for portable application. These advantages are mainly depends on overall system design and especially on stack operating performance. In order to increase the performance of the overall system, design criteria of a DMFC stack has been considered. A DMFC stack with optimum flow field, flow direction, uniform pressure drop and flow distribution has been constructed. Scale effects respect to the number of cells are tested on single cell, short stack and stack by a homemade test bench. The results are shown the scale effect respect to the number of cells is ignorable.
Rapid Analysis of the Triad Sequence Distributions of Ethylene-Propylene Rubber by IR-13C NMR-PLS
Authors: Zhao Xia , Xu Guang Tong
Published: February 2012

The triad sequence distributions of -EEE-、-EEP-、-EPE-、-PEP-、-PPE- and -PPP- of Ethylene-Propylene Rubber (EPR) has been determined by infrared spectroscopy (IR) combined with 13C NMR and partial least squares (PLS) chemo metric algorithm. The triad sequence distributions obtained by 13C NMR was used as reference date. PLS regression models of the sequence distributions of EPR have been developed by MIR range. The wave number range of IR was 1300~600cm-1 and the spectra were pretreated through smoothing and second derivation. The results showed the sequence distributions predicted by models were consisted with the data from 13C NMR. The triad sequence distributions of EPR could be fastly analyzed by IR models.
Parametric Optimization of Machining Ti-Alloys in Respect to Surface Roughness - A Review
Authors: Kazi Badrul Ahsan , Abdul Md Mazid
Published: February 2012

The uses of Titanium alloys have largely been increased due to the benefits which are very substantial in some specific areas. Their applications are not only limited to in aerospace industries and biomedical implants but also widely introduced in marine and automotive industries. Yet the optimum cutting conditions for those materials are still under investigation. Ti-alloys are in the group of difficult-to-machine materials due to their poor machinability. The main reasons behind their poor machinability are high chemical reactivity, low modulus of elasticity and low thermal conductivity. Here in this paper a number of literatures related to optimization of machining parameters are reviewed and the problems related to machining of these Ti-alloys including their effects are summarized.
Increase of Alternative and Renewable Energy Sources Utilization in Slovakia by 2020 in Comparison to other Selected EU Countries
Authors: Pavolová Henrieta , Senova Andrea , Bakalár Tomáš
Published: February 2012

One way to save fuel is to use renewable energy, including solar, wind, hydro, geothermal and biomass. The use of renewable and alternative energy sources is contributing to environmental protection and nature conservation as a whole and provides a perspective of sustainable development. The aim of this paper is to compare the possibility of increasing the use of alternative and renewable energy sources in Slovakia with neighboring countries. It determines and also identifies the level of the Slovak Republic in the use of renewable energy sources because it is expected to increase by 2020 in each country. This paper is also devoted to the theoretical base of renewable and alternative forms of energy. One part of the paper deals with an analysis and comparison of the state of the use of renewable energy sources in Slovakia and in selected EU countries. Latest part deals with the overall national objectives set by the European Union for the proportion of energy from RES, which will be achieved by 2020. The paper is a partial result of the research project on RES realized at Technical University of Košice (Slovakia).
Influence of Composition on the Corrosion of Steel Bar of Reinforced Geopolymer Concrete
Authors: Wang Qing , Da Jing , Zhang Cun Bao , Ding Zhao Yang , Sui Zhi Tong
Published: February 2012

The three key oxide molar ratios of geopolymer concrete: n(SiO2)/n(Al2O3), n(Na2O)/n(Al2O3) and n(H2O)/n(Na2O) were studied in this paper to determine their effects on reinforced geopolymer concrete by testing the corrosion weightless rates of reinforcing steel bar and carbonation depth. It was found that both of them were decreased first but increased at a certain point with increasing n(SiO2)/n(Al2O3); they showed a downtrend with the increase of n(Na2O)/n(Al2O3). Increasing n(H2O)/n(Na2O) caused an increase in both of them while a small decline was observed in carbonation depth when n(H2O)/n(Na2O)＜28.With the the same amount of cementitious material, resistance to corrosion of steel bar of geopolymer concrete was better than that of common concrete.
Environmental Effect on Fatigue Properties of Die-Cast Magnesium Alloys
Authors: Liu Ma Bao , Liu Qi Da , Wang Xian Hui , Gao Hong
Published: February 2012

In order to study the environmental effect on fatigue properties of die-cast magnesium alloys, several fatigue tests were performed for AM50HP and AZ91HP in ambient air, vacuum, engine oil, deionized water and 3.5% NaCl solution. It is found that the S-N curves are steeper in corrosive environment and AM50HP shows a higher sensitivity to the action of 3.5% NaCl solution than AZ91HP. Both alloys do not have endurance limits in 3.5% NaCl solution, whereas endurance limits could be detected in ambient air, which are about 90MPa and 100MPa for AZ91HP and AM50HP respectively. It is also found that FCP rate is substantially increased in corrosion media: the presence of oxygen causes the production of oxide film on the fresh surfaces made during the cyclic loading and the oxide film would restrict the deformation of the matrix beneath the hard film and promote hydrogen embrittlement in the wet condition.
Application of Smart Coating Sensor in Crack Detection for Aircraft
Authors: Liu Ma Bao , Wang Xian Hui , Liu Qi Da , Gao Hong
Published: February 2012

A novel smart coating sensor, consisted of driving layer, sensing layer and protective layer, has been successfully developed, and it was utilized to detect crack initiation and growth in fatigue tests. The results show that the smart coating sensor can detect cracks above 300μm, corresponding to the increment of the sensing layer’s resistance at the level of 0.05Ω. Subsequently, the development of SCS is of importance significance in the substitution of an existed inspection that requires substantial disassembly and surface preparation, and, thus, can find numerous applications in difficult-to-access locations on commercial and military aircrafts.
Modeling of the Transient Response for Compressible Air Cushion Vehicles (ACV)
Authors: Sowayan Ahmed S. , Alsaif Khalid A.
Published: February 2012

A model for compressible Air Cushion Vehicles (ACV) is presented. In this model the compressible Bernoulli's equation and the Newton's second law of motion are used to predict the dynamic behavior of the heave response of the ACV in both time and frequency domains. The mass flow rate inside the air cushion of this model is assumed to be constant. The self excited response and the cushion pressure of the ACV is calculated to understand the behavior of the system in order to assist in the design stage of such systems. It is shown in this study that the mass flow rate and the length of the vehicle's skirt are the most significant parameters which control the steady state behavior of the self excited oscillations of the ACV. An equation to predict the transient time of the oscillatory response or the settling time in terms of the system parameters of the ACV is developed. Based on the developed equations, the optimum parameters of the ACV that lead to minimum settling time are obtained.
High Temperature Properties of Magnesium Based Composites Prepared by Spark Plasma Sintering
Authors: Muhammad Wan Nur Azrina Binti Wan , Mutoh Yoshiharu , Miyashita Yukio
Published: February 2012

High temperature tensile test was conducted to study high temperature properties of the magnesium based composites reinforced with SiC particulates and monolithic magnesium as well. It was found that tensile strength of monolithic magnesium and Mg-SiC composites decreased with an increase in testing temperature. While the elongation to failure both samples were increased when increasing temperature. At all testing temperature, the tensile strength of the composite sample was found to be superior compared to monolithic magnesium due to presence of SiC particulates and efficiency of spark plasma sintering process in fabrication of the composites.
Comparison of Mechanical Properties of RE-7075 Al Alloy's Hot Rolled Sheet and Cold Rolled Sheet
Authors: Zhong Jian Hua , Zhu Hong Bin , Feng Kai , Xiao Yin Ping
Published: February 2012

The experiment has studied the mechanical properties effect of rare earth(RE)-7075 Al alloy＇s hot rolled sheet and cold rolled sheet coursing by two-step aging treatment. The hot rolled sheet and cold rolled sheet were analyzed by EDS(energy dispersive spectrometer), SEM(scanning electron microscope) and tested by Brinell Hardness tester, Computer-controlled electronic universal testing. The results shows that the synthetical mechanical properties of hot rolled sheet exceeds cold rolled sheet. The tensile strength is higher approximately 80MPa, elongation is larger approximately 3% and Brill hardness is bigger approximately 30HB after the two-step aging treatment.
The Oil Condition Analysis of Involute Spur Gear
Authors: Zhao Hui , Wang You Qiang
Published: February 2012

A gear microscopic surface pitting lubrication model was established, and the oil condition of it was introduced. Based on the multi-grid method, a numerical solution of spur gear oil condition lubrication was obtained. The result show that with the provided oil film thickness increases, the film thickness of the meshing point also increases. However, when it is added to a certain degree, the film thickness will no longer change, the phenomenon is worthy of discussion. The result shows that lack oil lubrication is detrimental to the gear, but it will not be better as the amout of oil adds, there exists a critical point.
Research on Crosswind Stability of FSAE Racing Car with Rear Wing at Different Attack Angles
Authors: Ni Jun , Chen Si Zhong , Feng Da , Wang Xu Jie , Hao Jia Xin
Published: February 2012

In order to analyze the performance of a certain FSAE racing car with rear wing at different attack angles by virtual prototyping technology. The multi-body model of a FSAE racing car which takes non-linear factors into consideration was built by applying ADAMS/Car. The correctness of the model is verified by comparison with the actual experiment result. By the simulation of the air resistance and lift characteristics of the rear wing, a feasible method to building the aerodynamic characteristics of the rear wing in multi-body model was proposed. Based on these, the crosswind stability of FSAE racing car with rear wing at different attack angles was analyzed, the result shows that the effect of crosswind is reduced with the increase of the attack angle of the rear wing.
Tool Wear of Diamond-Like Carbon-Coated High-Speed Steel with a Cr-Based Interlayer in Cutting of Aluminum Alloys
Authors: Wada Tadahiro , Iwamoto Koji , Sugita Hiroaki
Published: February 2012

In cutting aluminum alloy 6061, continuous chips have a negative influence on the machining operation. Usually, Pb is added in order to break continuous chips. However, from the standpoint of environmental protection, it is necessary to improve chip breakability without adding Pb. One effective measure to improve chip breakability is by adding Si to aluminum alloy 6061. However, the influence of Si content on tool wear has not been fully examined. In this study, in order to clarify the influence of a diamond-like carbon (DLC) coating layer with a Cr-based interlayer, namely (Al,Cr)N, on cutting performance, aluminum alloys having different Si contents were turned. The substrate of the tool material was high-speed steel (1.4%C). The tool wear and the surface roughness were experimentally investigated. The following results were obtained: (1) In cutting two kinds of Al-Si alloys, namely the Al-2%Si alloy and Al-4%Si alloy, the progress of wear of the DLC/(Al,Cr)N-coated tool was slower than that of the DLC-coated tool. Therefore, the (Al,Cr)N interlayer was effective for decreasing the tool wear of the DLC-coated tool. (2) The wear progress of the two kinds of DLC-coated tools in cutting of Al-4%Si alloy was faster than that in cutting of Al-2%Si alloy. (3) In cutting of Al-2%Si alloy with the (Al,Cr)N/DLC-coated tool, the surface roughness was almost constant in the range of a cutting distance from 0.1 km to 9.5 km.
Conceptual Design and Optimal Torque Sharing Strategy for Hybrid Vehicles with Epicyclic Gear Trains
Authors: Mir-Nasiri Nazim
Published: February 2012

The paper presents a novel approach in torque sharing between an internal combustion engine (IC engine) and two electrical motors for optimal drive of a hybrid vehicle. The concept of the system is realized by employing the three degrees of freedom (DOF) twin epicyclic gear train with specially selected gear ratios to satisfy an optimal power sharing strategy. The first stage of the train provides high torque from the IC engine and moderate torque from the motor M1. The second stage provides lower torque but higher speed from the motor M2. Such arrangement of power sources is achieved by carefully selecting of all the gear ratios in the train. The designed system is able to minimize the power usage of the IC engine and thus to minimize the exhaust gas emission, save cost of petrol as compared to normal petrol vehicle. It also provides a quite wide range of torque and speed values to drive the vehicle.
Approach and Effect Analysis of Amplitude Frequency Performance Improvement in Metal Bar Cropping with Variable Frequency Vibration
Authors: Zhang Li Jun , Xue Jie Qiong , Zhao Sheng Dun , Zhao Yong Rui
Published: February 2012

In order to solve the narrow range and control difficulties of the excited frequency in metal bar cropping with variable frequency vibration, the structure of the eccentric block in cropping machine was improved on in the paper and a new structure model of changing the integral eccentric block into one of main eccentric block and some small adjustable eccentric blocks, was also proposed. The key parameters of the cropping machine in the action of two different types of eccentric blocks were analyzed theoretically in detail. At the same time, the corresponding amplitude frequency characteristics of the cropping machine were also obtained. The cropping experimental results of 45 steel bar show that the cross-section quality and the cropping time are improved remarkably in the action of one main eccentric block and four adjustable eccentric blocks, comparing with the cropping results in the action of the whole eccentric block.
Forecast and Analysis on the Stability of Open-Pit Ultra-High Slope
Authors: Zhang Fei , Cao Jing , Chen Ming , Peng Lei
Published: February 2012

Combining the explicit Lagrangian difference method for the continuum body and strength reduction technology, this paper analyzed the stability of Xian Feng open-pit. The generalized shear strain and plastic strain interconnected within the weak structural plane of slope are used as criterion to identify slope failure state. Analysis of the example verifies that the criterion is rational. With the calculate model, it can predict the open-pit ultra-high slope stability after five years. Its results are similar to the traditional limit equilibrium method. Therefore, the method is reasonably practicable. So the result will be important significance to guide the post-construction of mine.
Effects of Ozone Treatment on Wool Scales and Mechanical Properties
Authors: Ning Fang Gang , Wang Jun , Yu Weidong
Published: February 2012

The aim of this study was to investigate the ozone treating effects on wool scales and wool fabrics mechanical property through experiments and observation. For this purpose, detailed investigations on the role of mechanical properties surfacing topography, changes in component and membrane structure were investigated. Then, a micro explanation was given to discuss the mechanism of wool shrinkage. Because scales are the necessary factor for shrinking, this study is of great significance to the work of shrinkproofing.
The Application of SEA in Automobile Dash Sound Transmission Loss Numerical Calculation
Authors: Mao Jie , Hao Zhi Yong , Chen Xin Rui , Yang Ji
Published: February 2012

In order to study the structure-borne sound radiation, statistical energy analysis (SEA) was adopted and an automobile dash was divided into 31 subsystems; the modal density, damping loss factor (DLF) and coupling loss factor (CLF) were acquired, which were the basic parameters of SEA; then dash transmission loss (TL) at the middle and high frequency (MHF) ranging from 100 Hz to 10k Hz was calculated. The most outstanding advantage of SEA was that calculation could be fast done, which was more convenient than FEM (Finite Element Method) and BEM (Boundary Element Method). Finally, a TL experiment was designed to verify the feasibility and reliability of numerical calculation. The 1/3 octave TL curves of the simulation and experiment show a good consistency and the error is engineering permitted, which means SEA simulation possesses high credibility and can guide the engineering research.
Beam Element Considering the Warping Effect of Cross Section in Large Displacement Finite Element Analysis
Authors: Li Peng Fei , Yuan Yuan , Liu Hong Zhao
Published: February 2012

A simple two-dimensional shear deformable finite beam element is developed in order to examine the effect of the high order interpolation on the modes of deformation of the beam cross section using the ANCF finite element. The new element allows for effect of warping that cannot be captured using previously introduced ANCF beam elements, and relaxes the assumption of planar cross section. The displacement field of the new element is assumed to be cubic in the axial direction and quadratic in the transverse direction. Using this displacement field, new shape functions are formulated and include the quadratic of the transverse direction instead of the linear expression. The displacement gradient and transverse strain component obtained using the new higher order element are introduced. Numerical example is presented in order to compare the results obtained using the new finite element and the results obtained using previously developed ANCF finite element. The results reveal that the cross section remains as a curve surface not a planar one.
New Model for Interlaced Yarns in the Ballistic Impact of Flexible Body Armors
Authors: Yavuz A. Kadir , Phoenix S. Leigh , Balkan D.K.
Published: February 2012

In this work, numerical implementations of a new biaxial fabric of interlaced yarns model for ballistic impact into flexible body armor are presented. First the model is applied to a single-layer panel of polyethylene Dyneema® fibers in a matrix and impacted by various projectile geometries. We obtain the model results from a mass-spring, finite-difference model by modifying the code first developed at DSM. The results of the model are compared with experimental results and our previous biaxial model from firing 9 mm and FSP projectiles into Dyneema® panels. For both models, parametric studies are presented using 2-D and 3-D graphics. The new biaxial interlaced yarns model extends our previous biaxial and axisymmetric membrane model by addressing biaxial influences on material inflow to the impact cone. The new model is much more complete and produces velocity, strain and deformation histories for the full system up to perforation or projectile halting. It can also treat cases of mixing different fabric types, which can result in interference effects depending on the layer stacking order, and can treat multiple layers with air gaps in between, where we will show that such gaps can seriously degrade performance.
IC Tomography and Infrared Tomography Techniques to Monitor Defect Sites in Palm Tree Trunks
Authors: Al-Sulaiman Faleh , Hawwa Muhammad
Published: February 2012

The sonic tomography and infrared thermograph techniques are incorporated to monitor the orientation and the size of the defect sites in the palm tree trunks. The tests are carried out for various conditions of the palm tree trunks, which have the large defect sites caused by the insects. The sonic tomography technique relies on the measurement of the relative sound wave speed by the detectors when the palm tree trunk is excited through the external forces. This technique enables to separate and quantify the damage and the intact volumes. It is found that sonic tomography can be used to identify the damage sites within a reasonable accuracy. The images obtained from the infrared thermograph technique provide information on the presence of the defect sites with the limited capacity for the location and the size of the defect sites in the palm tree trunk.
Product Improvement with Quality Function Deployment (QFD) Technique
Authors: Camgoz-Akdag Hatice , Zaim Selim , Acar Mehmet F. , Demirel Omer F. , Ataman Ahmet
Published: February 2012

The purpose of this paper is to improve a new part for the natural gas sector using Quality Function Deployment (QFD) technique. QFD methodology was chosen for the product improvement process at IGDAS (Istanbul natural gas distribution company), the biggest natural gas distribution firm in Turkey. Experts from engineers were selected to determine customer expectations. Application of QFD to pipe strangling equipment is described step by step. The results show that when developing a new product or improving a product both customer expectations and product requirements are evaluated at the same time pleasing both parties for a successful result.
Investigation of Rotation Elastic Boundary Condition on the Pull-In Instability of Electrostatic Torsional Actuators
Authors: Mahbobian Kamyar , Tadi Beni Y.
Published: February 2012

In this paper, the static pull-in instability of torsional nanoelectromechanical systems (NEMS) with coupling effect between torsion and bending is investigated considering the effect of translation elastic boundary condition. A set of normalized equations governing the static actuation properties of the torsional actuator is derived to demonstrate the relationships between the parameters of static characteristics, such as torsion angle, vertical displacement, and applied voltage. The results from this model demonstrated that the real model of boundary condition (elastic boundary condition) is very important issue which must be considered in manufacturing process.
Martensitic Phase Transformations in CuAlNi Shape Memory Alloys
Authors: Babacan N. , Gunel I. , Ozsoy I.B.
Published: February 2012

The main deformation mechanism of shape memory alloys (SMA) is martensitic phase transformation (PT). To model martensitic phase transformations in such materials, several models have been developed. In the micromechanical model developed by Levitas and Ozsoy (2009), complete system of equations that describes evolution of stresses in phases and crystallographic parameters, as well as macroscopic stress–strain response for martensitic phase transformations under complex multiaxial loadings have been formulated. However, the experimental verification is incomplete. The objective of this study is to compare the experimental results in the literature for CuAlNi SMA with the results obtained from this micromechanical model. In the experiment used for comparison (Shield, 1995), a single crystal CuAlNi specimen is subjected to uniaxial load in several directions at different temperatures. According to the results obtained by using the constitutive equations of the model, the model describes the stress induced phase transformations very well when compared with these experiments. The uniaxial loading-unloading hysteresis loop shows good agreement with the experiments.
Novel Spring and its Manufacturing Process for Semi Auto Sliding Mechanism to Maximize Function and Minimize Thickness of Portable Application
Authors: Jeon Y.P. , Seo H.Y. , Kang Chung Gil
Published: February 2012

Various portable applications such as a mobile phone, MP3 player, PMP player and so on, have been continuously developing with influencing on each other. In this environment, functions of IT applications have been built in the mobile phone, and consequently, the additions of them increase the size of the phone. However, the sizes of present phones have changed less than those of the past, and this trend is expected to be continued in the future because of the inherent characteristics mobility and portability of the phone. Great strides made in the industries manufacturing cellular phone components have facilitated the development of phones having similar size to the existing phone. However, in common, there are limitations on the extent to which the sizes of the parts can be reduced because of the technical reasons pertaining to mechanical or electrical properties, the forming process and assembly structure. In such a scenario, the use of a slide mechanism is the practical alternative for maintaining the mobility and portability. Reduction of the sliding space has a decisive effect on the decrease of the phone size. Therefore, a study of a novel spring to be manufactured by the etching process was performed to minimize the thickness. Meanwhile, the use of the slide mechanism is advantageous for maximizing visibility and increasing functionality with the limited space which are of utmost importance for the design of a contemporary cellular phone. In addition, various extra function keys including the main keypad buttons are required to maximize the visibility. However, the sliding stroke must increase to have them, and the existing spring units cannot be satisfied with the requirements under the limited space. Therefore, the study of a long-stroke spring unit and its manufacturing process to minimize the thickness with the stroke of 60 mm was performed.
A New Analytical Model of Heat Flux Distribution to Compute Residual Stresses in the Case of External Cylindrical Grinding Process
Authors: Sallem Haifa , Hamdi Hédi
Published: February 2012

Grinding process is an energy intensive process in the sense that, it requires a larger amount of energy per unit of volume of material removal compared to other metal cutting processes. In this case, effects on the ground workpiece in terms of induced residual stresses and metallurgical changes due to heat generated play an important role on the lifetime of parts in their mechanism. In order to investigate effects on the workpiece during external cylindrical grinding process, a new analytical approach is firstly developed to model the action of the grinding wheel as a heat flux, which moves along the workpiece surface. The value and the shape of the heat flux entering the workpiece are directly identified. Based on the established model, numerical simulations are performed to predict temperature, cooling and its effects on residual stress distribution in the ground near surface.
An Investigation into Hydroforming of an X-Shape Pipe Connection
Authors: Majzoobi G.H. , Farhoudi H.R. , Shirazi A.
Published: February 2012

In this work, hydroforming of X-shape pipe connection made of copper is investigated by experiment and numerical simulation. The length of the connection branch is always a concern. The main purpose of the work is the study of the effect of the branch end boundary condition and the load path on the branch height. An elastic material (called the constraint), such as a spring, is used for controlling the branch to grow to a certain extent. It is shown that the branch end condition, if designed properly, gives rise to the considerable increase in the branch length. The increase, however, depends also on the load path which must be determined by experiment or numerical simulation.
Multiobjective Optimization of Milling Tool Geometry for Chatter Suppression and Productivity Improvement
Authors: Yusoff Ahmad Razlan , Hassan Mohd Firdaus , Mansor Muhammad Hatifi
Published: February 2012

In this paper, productivity and self-excited vibration are simultaneously optimized using multiobjective optimization in cutting process. At high material removal rate, machining processes accelerates tool wear, poor surface finish and failure of machine parts. The effect of self-excited vibration or chatter prevents high machining productivity. This chatter vibration can be avoided by modifying tool geometry at low material removal rate but not at high productivity. To compensate material removal rate and chatter, multiobjective optimization is applied using ε-constraint algorithm to achieve a Pareto front solution. Differential Evolution as intelligent optimization algorithm is shown better results than traditional technique of Sequential Quadratic Programming.
Investigation of Micro/Milli Flexible Deep Drawing Process
Authors: Irthiea Ihsan , Green Graham , Hashim Safa
Published: February 2012

Flexible forming technology provides significant application potential in the manufacturing of complex shaped components even at miniaturized levels. The most attractive characteristic of this technology is simplicity, and its feasibility for prototype processes and low-volume production. The main purpose of this study is to clarify the decisive characteristics of micro deep drawing of metallic foils by using flexible forming technology. In this work a new technique is adopted using rigid punch, rigid holder and rubber pad, so that a particular gap is allocated between the blank holder and a fixed plate to allow the rubber pad to expand through it. The key process parameters studied here are rubber hardness, rubber-pad dimensions, drawing velocity, and initial gap value. Stainless steel 304 foils are used with thickness of 0.1mm. To investigate the effect of soft material properties, urethane rubber with hardness of 20, 40 and 60 shore A is utilized. Also, the punch diameter used in this study is 4mm. Moreover, many drawing experiments are conducted with punch velocities range of (0.1mm/s-100mm/s) to show the effect of process velocity. FEA using the commercial software ABAQUS/Standard is used to simulate the drawing process at micro scale. A hyperelastic material model is adopted to define the flexible pad and an elastic-plastic model is defined for the blanks.
Influence of Aging Temperatures and Times on Mechanical Properties of Vacuum High Pressure Die Cast Aluminum Alloy A356
Authors: Zhang Xue Zhi , Ahmmed Kazi , Wang Meng , Hu Henry
Published: February 2012

In this study a number of thermal treatment schemes over a wide range of temperatures between 120˚ to 350˚ C and times (30 120 minutes) have been experimented in an effort to understand the effect of thermal treatment on tensile properties of vacuum die cast modified aluminum alloy A356. The results show that, the morphology of eutectic silicon has a sound effect on the tensile properties of the tested alloy. The content of magnesium-based intermetallic phases, their morphology and distribution throughout the matrix affect the mechanical properties of the aged alloy as well. The reduction in the strengths of the alloy treated at 350°C for two hours should be at least attributed partly to the absence of the magnesium-based intermetallic phase. However the presence of sufficient amount of magnesium intermetallic phase had played important role in strengthening the alloy thermally treated at 200°C for 90 minutes.
Characteristics of As-Cast and Forged Biodegradable Mg-Ca Binary Alloy Immersed in Kokubo Simulated Body Fluid
Authors: Idris M.H. , Jafari Hassan , Harandi S.E. , Mirshahi M. , Koleyni S.
Published: February 2012

Biodegradable implant is an alternative to metallic implant and has the advantage of not being necessary to remove once the fracture has healed. Magnesium is particularly desirable since it is biocompatible and has a modulus of elasticity closer to bone. In addition, it shows ability to biodegrade in situ, when used as an implant material. In this research, different percentages of calcium were added to magnesium during melting of the alloy. A selected alloy was forged at different parameters. Both as cast and forged alloys were subjected to polarization test performed in Kokubo simulated body fluid. Immersion test in the fluid was conducted for 96 hours to investigate the formation, growth and morphology of the hydroxyapatite on the surface of the alloys. The results showed that similar electrochemical behaviour took place in the alloys regardless of the calcium content. However, an increase in corrosion rate was observed with increasing calcium content. It was also observed that forging process decreased the corrosion resistance of the alloy. Furthermore, increasing calcium content accelerated the growth of bone-like apatite in the alloy.
Influence of the Processing Conditions on the Mechanical Properties of PA 6 - Halloysite Nanotubes Nanocomposites for Injection Moulding
Authors: Fernandez Angel , Muniesa Manuel , Javierre Carlos , Camanes Victor
Published: February 2012

Nowadays polymer based nanocomposites are very interesting to manufacture products of less weight and higher mechanical properties and specific performance depending on the morphology of nanoscaled reinforcement. Most of these potential improvements are focused to the challenges newer products require like HEV (hybrid or electrical vehicles) for example. The development of these new products requires the full characterization of the rheological and mechanical behavior of the materials and the correct preparation of the raw material for further processing. As an example two nanocomposite blends were prepared letting down a masterbach of PA6+30% HNT (Halloysite nanotubes) to 3% and 6% of HNT content in a PA6 matrix of (BADADUR). The letting down process was developed in an extrusion-compounding machine (COPERION ZSK 26) and the rheological behavior was determined in a capillar rheometer obtaining the viscosity curves of the material needed for injection molding simulation. The products obtained were used for injection molding of test specimens in an electrical injection machine (JSW EL II 85). In addition, the letting down process was done directly in the injection machine in order to establish the relevance of the previous extrusion process. The probes obtained were analyzed by DSC and FTIR to determine the functional groups of the resultant product and SEM and TEM to determine the quality of the dispersion of the nanotubes. The probes were finally tested to determine its stiffness and tensile properties. The results showed the feasibility to develop parts made of nanocomposite with improved performance with scaled industry equipment with natural reinforcements..
Morphological Instability in Early Stages of Solidification of Pure Metals Part II: Experimental Analysis
Authors: Yigit Faruk
Published: February 2012

A simple experimental setup has been used to investigate the morphological instability observed in many solidification processes. It is shown that the mold with smooth surface exhibits prominent thickness nonuniformities. Periodic grooves in the mold surface results in more uniform contact along the mold-shell interface, and therefore leads more uniform growth of the shell. Experimental results for the moving solidification front have also been compared to the results of a simple theoretical model introduced in Part I, and a good agreement has been obtained.
The Properties of Lattice Structures Manufactured Using Selective Laser Melting
Authors: Shen Y. , Cantwell W.J. , Mines Robert A.W. , Ushijima K.
Published: February 2012

This paper outlines the findings of an on-going research study investigating the properties of a range of steel and titanium-based micro-lattice structures manufactured using the selective laser melting (SLM) technique. Initially, tension tests have been conducted on strands manufactured at different build angles. Micro-lattice block structures, with struts oriented at +/-45o were then tested in compression at quasi-static rates of loading. The failure mechanisms have been investigated using both optical and scanning electron microscopy. These tests have highlighted the attractive properties offered by these complex architectures.
Microstructural Characterisation and Investigation of the Effects of ZrSiO4-Y2O3 Additions on Corrosion Behaviour of MgO-Spinel Composite Refractories
Authors: Aksel Cemail , AKSOY Tuba
Published: February 2012

Corrosion resistance of MgO-Spinel (M-S) composite refractories containing various amounts of ZrSiO4-Y2O3 constituents was investigated. Density and open porosity values were measured and evaluated. Corrosion tests of refractories were carried out statically under standard conditions using cylindrical shaped samples in terms of determining the interaction with cement clinker. Corrosion resistance was determined by measuring the values of penetration and depth of the corroded regions of refractories. The influence of corrosion resistance based on the microstructural changes occurred as a result of solubilities of constituents in the interface of clinker-refractory for various regions was examined using SEM and the results were evaluated using EDX analysis. It was observed that there was a significant increase in density values and decrease in porosity data for most of the compositions obtained from the additions of ZrSiO4-Y2O3 to MgO-spinel. As a consequence of microstructural characterisation performed at the interface of clinker-refractory, the observations made were determined as follows: i) the formation of ZrO2 and Mg2SiO4 phases among the MgO grains during sintering, ii) the formation of CaZrO3 phase during penetration, iii) prevention of penetration by new phases formed that make a barrier effect against clinker with the improvement in densification, and iv) the decrease in the amount of CaO based on the EDX analysis made from clinker to refractory in a corroded region. The incorporation of ZrSiO4-Y2O3 into MgO-spinel reduced the values of penetration and depth of the corroded regions of refractories and improved the corrosion resistance. The penetration of clinker to refractory showed a minimum level for the composition of M-20%S-20%(ZrSiO4+Y2O3) and an improvement by a factor of 1.42 as compared to M-20%S. This development is also combined with a long service life of M-S-(ZrSiO4+Y2O3) containing composite refractories for industrial uses.
A Slip-Line Approach to the Micro-Cutting Process with a Rounded-Edge Tool
Authors: Uysal Alper , Ozturk Sabri , Altan Erhan
Published: February 2012

The effect of tool edge roundness attracts growing attention due to increasing applications of precision, micro-and nanomachining technologies. A new slip-line model and its associated hodograph are proposed for cutting with a rounded-edge tool in this paper. New model considers stagnant metal region called as dead metal zone formed in front of the rake face of tool during cutting process. Dewhurst and Collinss [ matrix technique for numerically solving the slip-line problem is employed in the mathematical formulation of the new model. The unknown slip-line angles were solved depending on the force data obtained from experiments and variation of the sub-regions with cutting edge radius was determined.
Influence of Mesh Density and Element Type on the Accuracy of FE Analysis of Periodic Cellular Structures
Authors: Kim Sang Woo , Kwon Yong Nam , Kang Beom Soo
Published: February 2012

Metallic sandwich panels based on lattice cell structures have been developed for a wide range of potential applications with their lightweight and multi-functionality. Structural performance of sandwich panels can be predicted from the studies on the mechanical properties of a unit cell. Numerical investigations on the unit cell can provide efficient guidelines for the design of overall core structures for a specific application. When any types of external forces are applied on the sandwich panel, each truss member of the unit cell undergoes severe plastic deformation without any restrictions so that the deformation behavior is strongly dependent on mesh density and element type. Therefore, in order to improve simulation accuracy and minimize calculation time, it is necessary to investigate the influence of element type and mesh density on that. In this work, as the preparatory stage to predict the mechanical behavior of a pyramidal unit cell, a series of finite element simulations for various element sizes and types were carried out. The influence of mesh density and element type on the simulation accuracy was investigated in diverse aspects; calculation time, resultant load, deformed geometry, effective modulus and peak stress.
Laser Nitriding of Titanium Alloy and Fracture Toughness Measurement of Resulting Surface
Authors: Al-Mana O. , Hashmi M.S.J. , Yilbas Bekir Sami
Published: February 2012

In the present study laser nitriding of titanium alloy surface is carried out and fracture toughness of the resulting surface is measured using the micro-indentation method. The fracture toughness is then related to the microstructure of the laser treated surface. It is found that laser gas assisted nitriding lowers the fracture toughness of the surface due to the micro-stress formed at the surface region during the high cooling rates.
HVOF Coating of Metallic Surfaces Using Different Powders: Fracture Toughness Measurement of Resulting Surfaces
Authors: Al-Shehri Y.A. , Hashmi M.S.J. , Yilbas Bekir Sami
Published: February 2012

In the present study, two layer HVOF coatings of carbon steel is carried out. The microstructural changes in the coating layers and fracture toughness of the coated surface are examined. The micro indentation method is incorporated for the fracture toughness measurements, while optical and scanning electron microscopy are used for the microstructural analysis. It is found that the fracture toughness of the coating surface produced by the tungsten carbide blended powders is less than that of the coating produced by corrosion resistance powders. Key words: HVOF, Diamalloy 2002, Diamalloy 4010, Fracture toughness.
Hydroxyapatite Coating on Cp-Ti Implants by Biomimetic Method
Authors: Elkoca Oktay , Yoruç A. Binnaz Hazar , Karakas Aysu , Koyun Ahmet
Published: February 2012

Hydroxyapatite (HA) is the main inorganic component in the human hard tissues, such as bones and teeth. The use of HA in load-bearing orthopedic applications has been extensively studied to achieve a biocompatible coating layer on implant metals. Commercial pure titanium (cp-Ti) is the most commonly used metallic material in the manufacture of orthopedic implants. Uncoated metal surfaces generally show numerous toxic effects to the surrounding tissues. However, coating of the metallic surfaces before implantation may prevent the interference of implant surfaces in biological media and also could accelerate the new bone formation. The present study focused on the coating of HA on cp-Ti implants, using novel biomimetic sol-gel method. The surfaces of cp-titanium substrates were coated with novel biomimetic sol gel (BSG) method under biological conditions (37°C and pH= 7.4). A bone-like apatite with a nanosized and pure HA structure was formed on the substrates under atmospheric pressure. The pre-coating results indicate that the novel biomimetic sol gel method is definitely a promising coating route in case that optimum coating parameters are established in detail.