bluuebunny/crossref_metadata_2025 huggingface dataset:
Roughness Based Analysis of the Influence of Tool Coating in the Dry Turning of UNS R56400 Ti Alloy
Authors: Salguero Jorge , Gerez Julia , Batista Moises , Gómez-Parra Álvaro , Mayuet Pedro F. , Marcos Bárcena Mariano
Published: February 2012

Light alloys, such as Aluminium or Titanium based alloys are frequently used in the aircraft industry. In the particular case of Ti alloys, they are usually commonly turned for obtaining strategic airships parts under rigorous quality requirements, in order guarantee the functionality of the workpiece design conditions. So, the analysis of the finishing quality of the turned pieces is essential in the quality control process. In this paper a study of the finishing quality of dry turned UNS R56400 Ti alloy has been achieved on the basis of the analysis of workpiece surface roughness, Ra, as a function of cutting parameters, such as feed and cutting speed. In parallel, a comparative analysis of the influence of the tool coating has been achieved. The obtained results have shown that coated tools cause a worse surface finishing quality.
Smokeless Chemical Polishing Practical Techniques
Authors: Zhang Ju Guo , Zhu Hong Bin
Published: February 2012

In order to eliminate the hazards made by traditional three acid polishing on the environment and human health, the polishing quality influence was studied, which was brought by the additives such as the oxidant, corrosion inhibitor and surfactant, the affect that actual situation acted on the polishing time and temperature was described at the same time, on this basis, the optimum process parameters was determined. Under this process conditions, the better polishing effect was obtained, the yellow smoke pollution in chemical polishing successfully resolved and problem of the economic cost brought by substitution of three acid polishing was settled, which will meet the needs of industrial production.
Poly(ε-Caprolactone)-b-Hyperbranched Polyglycidol for Targeted Drug Delivery
Authors: Li Xiao Hui , Wang Liang , Yang Jing , Song Cun Xian
Published: February 2012

A bolock copolymer of poly(ε-caprolactone) and hyperbranched polyglycidol (PCL-b-HPG) was synthezed by “living” copolymerization of ε-caprolactone (CL) and glycidol. The chemical structure was confirmed by 1H NMR, IR and GPC spectrum. Nanoparticles (NPs) of 50–100 nm were formulated from the PCL-b-HPG copolymer with no evidence of particles aggregation as determined by TEM. RGD peptide was covalently coupled on the end hydroxyl groups that could enable recepter–mediated recongnation onto targeted tissues. In conclusion, a hyperbranched copolymer PCL-b-HPG was synthezed by a novel and simple approach. The numerous functional end-groups could facilitate the attachment of biomolecules for further investigation as targeted drug delivery.
Twist-Bend Coupling Analysis for 5MW Wind Turbine Blades
Authors: Zhou Xing Yin , An Li Qiang , Wang Zhang Qi
Published: February 2012

Twist-bend coupling is a very important way to reduce the fatigue loads for megawatt blades. This paper studied the twist-bend coupling properties of 5MW wind turbine blades using finite element method. Twist angle, flapwise bending angle and coupling parameter are given for each aspect by applying same loading condition. Simulated results show that material can greatly affect the coupling properties while the influence induced by the structure of blade can be ignored.
Performance Analysis of the Flotation Cushion with Elastic Pressure Equalizing Groove for Aerostatic Slideway
Authors: Zhang Jun An , Dong Hao , Ma Fang Jie , Liu Bo
Published: February 2012

In order to improve stiffness of the flotation cushion, a new type of flotation cushion with variable-section pressure equalizing groove of elastic plate for aerostatic slideway was designed. Gas film pressure distribution and load carrying capacity of this flotation cushion was studied through theoretical analysis. The grid was generated by taking advantage of overlapping stitching technique. By using the coupling calculation of the gas lubrication governing equation and elastic deformation of thin plate governing equation, the load carrying capacity and stiffness of the new flotation cushion were obtained. Some experiments were made to verify the result of theoretical calculation. The experimental results show that the stiffness of new flotation cushion is much higher than conventional flotation cushion.This new flotation cushion has a wider application space.
Modeling Quasi-Static Errors in a Five-Axis Gantry Machine Tool
Authors: Yin Jian , Li Ming , Pan Fang Yu
Published: February 2012

Enhancing the accuracy of machine tool is a key goal of machine tool manufactures and users. To characterize the Quasi-static errors and then use software compensation is an important step for accuracy enhancement. The effectiveness of an error compensation scheme relies heavily on the error model. The model must be concise and roust which can be applied to any machine tool. The total Quasi-static errors within the workspace of a five-axis gantry machine tool is composed of geometric error, kinematic error, thermal error. This paper presents an error model which can be used for practical compensation scheme. Homogeneous transformation matrix, rigid body kinematic and small angle approximations are used in this paper for error modeling.
Research on Applying the Reborn Resource and New Materials for Energy Saving and Protecting Environment in the Design of Green Ecological Residential Building Design at the Super Cold District
Authors: Qian Yong Mei , Jin Yu Jie , Tian Wei
Published: February 2012

Through theoretical analysis for reborn resource and new materials，the paper mainly researches the significance about applying the reborn resource and new materials for energy saving and protecting environment in the design of green ecological residential building design at the super cold district, and feasibility in the design of green resident building design at the super cold district. The results will put forward the theoretical basis for the utility of new resource in the green resident building design and promote the extensive apply of them.
Under Uniformly Distributed Load are Fixed on one Side (Simple) on the Edge Simply Supported and Fixed Half Bending of Rectangular Plates
Authors: Chen Ying Jie , Fu Bao Lian , Wang Liang , Wu Jie
Published: February 2012

In this paper mixed variable method is generalized to solve the problem of bending of the rectangular plate with one side is fixed (simple) on the edge simply supported and fixed half under the action of a uniformly distributed load. Gives the surface deflection equation and a chart, the chart can be directly applied to engineering practice.
A Study of the Spray Characterization from a Centrifugal Nozzle by Pulsed Laser Holography
Authors: Cao Na , Cao Liang , Han Chang Cai , Xu Qing , Lei Lan , Du Ji Ye , Xue Jun , Zhang Zhan Hong
Published: February 2012

Centrifugal nozzle is an important part of an areoengine in which fuel atomization has strong influence on engine performance. For investigating the fuel spray characteristics, a promising method named off-axis particle holographic measuring system is used here. Characteristics of the nonevaporating spray ejected from a new type of centrifugal nozzle which would be used in the near future are obtained under various injection conditions. By automatic analysis of the holographic reconstructed droplets images, a hollow-cone shape spray with most droplets concentrated in the surface of the cone is observed, and the spray cone angle, droplet sizes and their spatial locations in concerned region are obtained quantitativly. In the near region of the nozzle exit, droplets show greater SMD value, while at a certain distance from the nozzle, the droplets SMD differences become unconspicuous which shows a better atomization. These informations are helpful to understand characteristics of the centrifugal nozzle and offer a database for validating the spray simulation code.
An Effective Route to the Fabrication of Super-Hydrophobic Surfaces Combined by Micromolding and Photograft Polymerization Methods
Authors: Yang Jing Tao , Wang Lei , Huo Zheng Yuan , Feng Jie , Chen Feng , Zhong Ming Qiang
Published: February 2012

A super-hydrophobic surface on the polypropylene matrix was fabricated via micromolding and photograft polymerization. A micro-convex body structure was molded by etching templates. The water contact angle could be increased to 138°. The fluoro methacrylate monomers were further grafted to the surface through UV-induced photograft polymerization. The morphology characterization and the spectroanalysis indicated that the rough hierarchical structure (confirmed by scanning electron microscope) and the grafted fluoropolymers (measured by fourier transform infrared spectrum and X-ray energy dispersive spectrometer) made a critical difference. A water contact angle of 160° was arrived.
Stress Analysis of Internal Wall Worn Casing String under Uniform Earth Pressure Based on ANSYS
Authors: Cao Yin Ping , Dou Yi Hua , Yu Yang
Published: February 2012

Wear of casing string is a common phenomenon in the process of oil and gas exploitation, and it reduces collapse and burst strength of casing string. Stress of internal wall worn casing string must be analyzed to ensure strength of casing string. In the paper, wear form of casing string is assumed as a crescent-shape, and a half finite element model (FEM) of worn casing string, cement-loop and earth combined system is established using the symmetry. Geometry relationships of wear ratio (or wear depth) and the centre of drill pipe are established. Effects of variables such as wear ratio of casing string, magnification factor of wellbore, elastic modulus of cement-loop and working conditions on casing string stress are discussed respectively. Some conclusions are drawn: maximum stress in casing string increases with increased wear ratio of casing string, and ultimately exceeds the yield limit. Increase of magnification factor of wellbore will improve bearing capacity of casing string, but maximum stress in casing string decreases slower and slower with further increase in magnification factor of casing string, at the same time, stress decreases more in casing string than in cement-loop. Minimum stress in cement-loop increases and maximum stress in cement-loop fluctuates with increased elastic modulus of cement-loop, while both minimum and maximum stress in casing string first increases then decreases, the turning point is related to elastic modulus of casing string and earth, as well as the geometry relationships among them. The bigger pressure difference, the larger maximum stress exists in casing string.
Study on LCF Lifetime Prediction of Thermal Shock
Authors: Zhao Wei Mao , Zhang Wei Zheng , Qin Zhao Ju
Published: February 2012

Gray cast iron specimen was heated to a fixed temperature with high frequency induction heating equipment, then was cooled to room temperature by spraying water to the heated surface. This process was repeated until a crack whose length exceeds 3mm appeared. Transient cyclic heat transfer and stress-strain FEA analysis was conducted to obtain specimen’s stress-strain state, then different LCF life prediction methods based on strain and energy were presented and contrasted, and results showed modified dissipated energy method with maximal hydrostatic pressure was more accurate than other methods. With the help of modified dissipated energy method, the relationship between thermal shock life, highest cooling temperature and cooling speed was studied, and the effect law of highest cooling temperature and cooling heat transfer coefficient on life was obtained.
Pressure Fluctuation of the Low Specific Speed Centrifugal Pump
Authors: Fu Qiang , Yuan Shou Qi , Zhu Rong Sheng
Published: February 2012

In order to study the rules of pressure fluctuation and the radial force under different positions in a centrifugal pump with low specific speed, and to find the relationship between each other, the three-dimensional ,unsteady Reynolds-averaged Navier-stokes equations with shear stress transport turbulent models were solved. The pressure fluctuation was obtained. The results showed that the pressure fluctuations were visible. The pressure fluctuations in the volute were relatively low at the design flow rate condition. The blade passing frequency dominates the pressure fluctuations, high frequency contents were found on the outlet of impeller but no high frequency information occured in casing. The radial force on the impeller was unsteady especially at the small flow rate.
Study on Magnetic Field for Navigation of Articulated Needle
Authors: Huang Hua Fang , Wang Yi Zhong , Zhou Zong Guo , Chen Yong Hua
Published: February 2012

When the magnetic articulated needle is inserting, the magnetic field which can produce the magnetic force of variable direction is required in order to implement the magnetic navigation in three-dimensional space. The paper puts forward a method for generating three-dimensional magnetic field based on the rotaion and translation of multiple permanent magnets. In this method, multiple permanent magnets form a circumference array. Every permanent magnet can rotate around the spin axis of itself in the array plane and move along the direction vertical to the array plane. Thus, in the array center, a magnetic fied which can produce the uniform magnetic flux density is obtained. The direction of magnetic fied is controllable in three-dimensional space and the magnitude of magnetic flux density is variable in a certain range. The simulations by ANSYS verify the feasibility of the proposed method.
On the Stability of Discrete Models of Compressed Beams in Elastic Media
Authors: de Angelis Fabio
Published: February 2012

The equilibrium configurations of compressed elastic beams in an elastic medium are investigated. The analysis is performed on discrete models by means of a geometric non linear treatment. The effect of the elastic stiffness of the medium on the overall stability of the structural system is taken into account through a parameter which represents the ratio between the elastic medium stiffness and the beam stiffness. This parameter shows to have a great influence on the buckling and post-buckling behaviour of the structure.
Joint Stress Optimization by the Hybrid Adhesive Lap Joint
Authors: Ozer Halil , Oz Ozkan
Published: February 2012

Hybrid adhesive joint is an alternative stress reduction technique for the adhesively bonded joints. Hybrid adhesive means that it is used dual adhesives in the overlap region. Adhesive having high modulus of elasticity should be located in the middle of the bondline and the other adhesive having low modulus of elasticity at the ends. In this study, the effect of the hybrid adhesive bondline on the distributions of the peeling, shear and von Mises stress components at the single lap joint were investigated by using three-dimensional finite element model. The results show that the considered stress components can be optimized by using hybrid adhesive joint.
Numerical Study of Hand Disc Grinding of Ni-Base Alloy 690
Authors: Youssef Sawsen , Calonne O. , Feulvarch E. , Gilles P. , Hamdi Hédi
Published: February 2012

The state of the surface, whatever the metal or alloy used is of paramount importance. Hand disc grinding operation is difficult to master in terms of results on the surface due to its manual nature. From this, comes the great importance to the mastery of the consequences induced by this abrasive process. A previous experimental study on hand disc grinding revealed several consequences on the surface integrity in terms of residual stresses, micro-hardness, hardening of the material etc. Numerical simulation can be a good way to prevent manufacturers of very time consuming experiments for the prediction of residual stresses due to grinding. The purpose of this study is to predict the consequences in terms of induced temperature fields and the state of residual stresses. The action of the disk-grinding wheel on the Workpiece is modeled by a moving heat flux on top of the part surface. All the difficulties lie in the quantification of the heat flux and more precisely in the heat flux density that gives the way the thermal load is distributed in the contact disk grinding/workpiece area. In this paper, an original analytical model for the determination of the heat flux density has been developed. For each step, the thermo-mechanical calculation is performed. Finally, the distribution of temperature and residual stresses will be carried out with the FE software SYSWELD 2010®.
Just-In Time Production System Using Fuzzy Logic Approach and a Simulation Application
Authors: Ozdemir Yavuz , Alcan Pelin , Basligil Huseyin , Dokuz Cagri
Published: February 2012

While firms are operating in a global competitive environment, they are subjected to changes because of the increased competitiveness and developed technologies. Therefore, this transformation process forces to produce with just-in-time production and low cost products or services and leads to customer satisfaction. Until today, competitive conditions, efficiency, productivity and quality of production, forced the firms to put more emphasis on production systems. Therefore, the firms are more interested in scientific analysis, planning and controlling of their production systems. As a result, one of the newest approaches is Just in Time (JIT) production system which emerged after WWII in Japan and aims to decrease the inventory cost and maximize the quality. The philosophy of this approach is to produce the necessary amount of production, when and where needed at the required quality. But JIT production system is weak in unclear species. For this purpose, the general and necessary solution is using fuzzy logic. In this paper we discussed about the simulation of an assembly line with 3 steps; firstly using Kanban production method, secondly non-using Kanban production method, and lastly using Kanban production method with fuzzy times. And also the comparisons of these steps will also be studied in this paper.
Modeling the Hydrodynamic Lubrication Function of Scrapings in Machine Tool Slideways
Authors: Parvaz Hadi , Nategh Mohammad Javad
Published: February 2012

Slideways in machine tools are usually scraped to form small oil reservoirs serving as hydrodynamic wedges to generate hydrodynamic pressure and separate the carriage from the slideway during the sliding movement of the carriage. The pressure distribution and load carrying capacity are among the most important parameters in these hydrodynamic bearings. In the present work, the hydrodynamic lubrication theory has been adapted for use in modeling the hydrodynamic lubrication function of scrapings in machine tool slideways. A specially designed experimental setup was employed to verify the theoretical estimation for pressure distribution in scrapings. The experiments were implemented by using capillary tubes mounted in different distances along the scrapings for obtaining the profile of the hydrodynamic pressure distribution. The ram effect could also be clearly distinguished which exhibited its role with a pressure rise at the inlet to the bearing.
Failure Analysis of Heavy Industrial Gas Turbine Engine First Stage Nozzel Guide Vane
Authors: Mustafa Alaaeldin H.
Published: February 2012

Failure analysis investigation was conducted on 70 MW set of 1st stage turbine nozzle guide vanes (NGVs) of heavy industrial gas turbine. The failure was investigated using the light optical microscope (LOM), X-ray diffraction analysis (XRD) and energy dispersive X-ray spectroscopy (EDS) in an environmental scanning electron microscope (ESEM). The results of the analysis indicate that the NGVs which were made of Co base superalloy FSX-414 had been operated above the recommended operating hours under different fuel types in addition to inadequate repair process in previous repair removal. The XRD analysis of the fractured areas sample shows presence ofwhich might indicate the prolonged operation at high temperature. Keywords: cobalt-base; nozzle guide vanes, gas turbine.
Investigation of the Dynamic Behaviors of Cranes under Seismic Effects with Theoretical and Experimental Study
Authors: Sagirli Ahmet , Azeloglu C. Oktay
Published: February 2012

This paper is concerned with investigation of the dynamic behaviors of cranes under seismic effects. For this purpose, firstly we have performed experiment on a 1/20 scale crane model on the shake table with real earthquake data, then a multi degree-of-freedom non-linear mathematical model is developed including behavior of the container cranes under earthquakes and simulated. The simulation system has a five degrees-of-freedom and modeled system was simulated for the ground motion of the El Centro earthquake in USA, 1940. Finally, the time history of the crane bridge displacement and acceleration responses of the both theoretical and experimental cases are presented. Theoretical and experimental results exhibit that the mathematical model is accurate. This study also shows the destructive effects of high accelerations which occur during the earthquake. These effects cannot be omitted in the design of cranes. The result of this study which is an accurate mathematical model can be inspiring for the engineers in terms of design parameters.
Application of Separated Die Design to Production of Ecap Dies
Authors: Erol Akata Huseyin
Published: February 2012

Metal forming processes with principally shear stresses that very high plastic strains are obtained in one pass are defined as severe plastic deformation (SPD) processes. Strain values can additionally be increased with additional passes throughout the process. Equal channel angular processing (ECAP) is the most applied method among the SPD processes due to relative ease of die manufacturing. On the other hand, die failures like corner cracking are frequently observed due to high notch effect and therefore use of the dies is limited. In the presenting study multi element die design (separated die design) approach was applied to production of ECAP dies in order to eliminate die failures and 5083 Aluminum alloy specimen were deformed with several passes. Although some additional development for die arrangement and fixation are needed, corner cracking was never observed and dies could be used safely.
A New Nondestructive Test Equipment Based on Image Processing and Magnetic Flux Analysis
Authors: Buyuksahin Utku , Kirli Ahmet
Published: February 2012

Nondestructive testing (NDT) methods has been increased within recent years depending on the needs of industry, parallel to new technological developments. Many studies have focused on thermal imagining, magnetic flux analysis or both, which are used in order to detect the deformation on surface and under the surface. In this study a new technique is suggested to eliminate the perturbations which are distorting effects of one point cameras in terms of perspective. A new integration is also proposed in this research such as using image recognition with magnetic flux analysis. Taking advantage of this integration and the new approach to image processing, both the surface and the inside of a mechanical product can be tested properly.
Mechanical Properties of Equal-Channel Angular Extrusion-Processed Al-20Zn Alloy
Authors: Aydin Murat , Heyal Yakup
Published: February 2012

The mechanical properties mainly tensile properties, impact toughness and high-cycle fatigue properties, of two-phase Al-20Zn alloy subjected to severe plastic deformation (SPD) via equal-channel angular extrusion (ECAE) using route A up to 2 passes were studied. The ECAE almost completely eliminated as-cast dendritic microstructure including casting defects such as micro porosities. A refined microstructure consisting of elongated micro constituents, α and α+η eutectic phases, formed after ECAE via route A. As a result of this microstructural change, mechanical properties mainly the impact toughness and fatigue performance of the as-cast Al-20Zn alloy increased significantly through the ECAE. The rates of increase in fatigue endurance limit are approximately 74 % after one pass and 89 % after two passes while the increase in impact toughness is 122 %. Also the yield and tensile strengths of the alloy increase with ECAE. However, no considerable change occurred in hardness and percentage elongation of the alloy. It was also observed that the ECAE changed the nature of the fatigue fracture characteristics of the as-cast Al-20Zn alloy.
The DMA, TG/DTA and FT-IR Characteristics of Wood Polymer Composites
Authors: Koyun Ahmet , Ahlatcioglu Esma , Erdogan Duygu Ceylan , Ipek Yeliz Koca
Published: February 2012

Wood chips and polymer composites are effectively used in the industrial products. It is important to establish a relationship between mechanical strength and processability in extruder of these composites. Especially, the most important factor is to determine the time-dependent strength. Although many short-term values were obtained via normal mechanical experiments, very little effort has been spent in order to estimate the long-term behavior of polymer. Composites were prepared with processed and unprocessed wood chips. Pretreatment of wood chips were carried out by using hydrochloric acid (HCl) and water. The products were prepared with different ratios of mixtures which contain wood chips and high density polyethylene (HDPE) grains. The long-term mechanical behavior and viscoelastic behavior of these composites were analyzed using Dynamic Mechanic Analyzer (DMA) test equipment. The effect of composite content and pretreatment method of wood chips on mechanical strength of wood plastic composites (WPCs) were determined. The relationship among the composite content, preparation method of wood chips, DMA and TG/DTA test results were tried to establish. FT-IR spectrums of the beginning materials and the composites are also examined in order to determine the chemical bonds of these materials.
Bearing Design Simulation in Direct Extrusion of AA2024 Using Finite Element
Authors: Shankayi M. , Soleimanimehr H. , Rahmanabadi M.R. , Shafighi A.R.
Published: February 2012

Extrusion is a metal forming process which involves plastic deformations. Economic significance of extrusion is due to its material efficiency, labor costs reduction, elimination of intermediate treatments, better output quality, and high production rates. Bearing length is one of the important features in extrusion dies. The aim is to make all the material points in outgoing profile have the same flow velocity, so in an effective design the flow velocity of thick features is controlled to be same as for thinner features. AA2024 alloy is widely used in military and aerospace industries. It has a high heat treatment capacity and strength to weight ratio. Other characteristics include excellent toughness, fatigue behavior, crack growth resistance, and machinability. However it is difficult to extrude. The purpose of this paper is to determine a strategy for designing bearings in direct extrusion dies which are used in production of parts from AA2024 aluminum alloy. Proper design of bearings is among factors of controlling material flow in this process and has an important role in scrap rate reduction. Using ABAQUS finite element software package, direct extrusion process is simulated. Results are explored and investigated for different conditions and finally, an efficient bearing configuration is introduced. Finally, it is shown that using uniform bearing for complicated sections is not possible. Optimum design is also presented using finite element analysis.
Roll Casting of Aluminum Alloy Strip by a Single Roll Caster Equipped with a Scraper
Authors: Haga Toshio , Akitsu Kazuya , Kumai Shinji , Watari Hisaki
Published: February 2012

A single roll caster equipped with a scraper was devised to cast the strip with sound free solidified surface. A property of this single caster is equipment of the scraper. Semisolid metal on the free solidified surface was scribed by a scraper and the surface became flat. Center line segregation did not occur as the strip was solidified from single side. The AA5182 aluminum alloy could be cast at speeds up to 40m/min. Thickness was about 3mm. Pressure of the unit width from the scraper was ranging from 0.1N/mm to 1.0N/mm, and these pressure was enough to make the free solidified surface flat. Roll cast strip could be cold rolled down to 1mm. There was not difference between roll contact surface and the free solidified surface after cold rolling by a visual examination. Result of tension test of the roll cast strip was as same as that of D.C. cast and rolled strip. Deep drawing test was operated at the conditions both of the roll contact surface and the free solidified surface was outside. LDR (limited drawing ratio) was same at both conditions and they were 1.8. Thickness of the strip was controlled by the roll speed, solidification length (length of the melt pool) and pressure of the scraper. The single roll caster is simpler than a twin roll caster. Rigidity for rolling was not needed for the single roll caster. Cost of the roll is half comparing a twin roll caster. The equipment cost of the single roll caster is more economy than that of the twin roll caster.
Usability of Boron as an Alloying Element in Gray Cast Iron Rollers and its Effect to Abrasive Wear Behaviour
Authors: Meran Cemal , Yuksel Mehmet
Published: February 2012

In this study, usability of boron as an alloy element in gray cast iron and its effect to abrasive wear behaviour were investigated. Pin-on-drum wear tests at the room temperature carried out for seven low nickels alloyed gray cast irons with different boron addition. The mass losses, hardness values and microstructures for gray cast iron specimens with different boron alloyed were investigated for determining wear behaviour. The pin for the wear tests was manufactured from X210Cr12 cold work tool steel with material number of 1.2080. Abrasive pin-on-drum wear tests were carried out at a 165 N constant load and two different sliding speeds that are closely related to the appropriate operating conditions in rolling mills. The experimental studies have shown that wear rate decrease with increasing boron amount in chemical composition of the alloy and the wear rate at high sliding speed has decreased more rapidly than the rate at the low sliding speed with increasing boron amount.
Flexural Characteristics of Tapered Bar in Relation to Taper Angle Measurements
Authors: Alzaharnah Iyad T. , Yilbas Bekir Sami
Published: February 2012

Flexural motion of a cantilever bar can be used to monitor the taper angle measurements of the bar without incorporating any geometric measurement. This provides non-destructive taper measurement with fast processing in manufacturing line. The laser ablation of a free end of the cantilever bar enables to generate a recoil pressure at the irradiated surface while resulting in external forcing function for the initiation of the flexural motion. Consequently, in the present study, laser induced ablation of free end tapered cantilever bar and resulting displacement and frequency of the flexural motion is examined. The study is extended to include influence of positive and negative bar taper angles on the flexural characteristics. In addition, deviation of displacement and frequency of the flexural motion due to tapered bar from the parallel bar is examined. It is found that the flexural characteristics of the tapered bar enable to determine taper angle of the bar with high accuracy.
Effect of Laser Welding Parameters on Forming Behavior of Tailor Welded Blanks
Authors: Korouyeh R. Safdarian , Naeini Hassan Moslemi , Torkamany M.J. , Sabaghzadee J.
Published: February 2012

Tailor Welded Blanks (TWB) are blanks in which two or more sheets of similar or dissimilar materials, thicknesses, coatings etc. are welded together to form a single sheet before forming. Forming behavior of TWBs is affected by thickness ratio, strength ratio, weld conditions such as weld properties, weld orientation, weld location etc. In this work, Nd:YAG laser welding will be use to weld TWB with different thickness in experimental test. Nd:YAG laser welding parameters such as pulse duration, welding velocity, frequency and peak power will affect formability of TWBs. Taguchis design of experiments methodology is followed to design of experiment and obtain the percentage contribution of factors considered. Erichsen formability test and uniaxial tensile test (ASTM-E8) will be use in experiment setup to compare result of different welding parameters on formability quality of TWBs.
Laser Cutting of Thin Aluminum and Silicon Alloy: Influence of Laser Power on Kerf Width
Authors: Yilbas Bekir Sami , Akhtar S.S. , Bayraktar E. , Gasem Zuhair M.
Published: February 2012

Laser cutting of aluminum-silicon sheet is carried out. The influence of laser output power on the kerf width is examined in details. The lump parameter analysis is introduced to predict the kerf width size. The percentage of kerf width size variation due to different laser output power levels is formulated. It is found that the kerf width size predicted agrees well with the experimental data. The influence of laser output power on the kerf width size is more pronounced for power levels 350 W. Keywords: laser cutting, aluminum-silicon, kerf width
Perovskite Based Anode Materials for Solid Oxide Fuel Cell Application: A Review
Authors: Rahman I.Z. , Raza M.A. , Rahman M.A.
Published: February 2012

Perovskites have gained attraction as electrode and interconnect materials for Solid Oxide Fuel Cells (SOFCs) due to their catalytic, ionic and electrical conductivities, chemical and thermal stabilities at higher temperatures. The operation and efficiency of SOFC depends mainly on the electrodes. Each electrode, anode and cathode, has demanding materials selection criteria. State of the art nickel-yittria stabilized zirconia cermet anodes are unable to work efficiently with hydrocarbon fuels and at intermediate operating temperature range (600-800°C). Hence, there is an increasing demand for the development of alternate anode materials to improve the fuel flexibility and efficiency of SOFCs. Perovskite based materials have oxygen ion vacancies depending on composition, temperature, and surrounding crystalline environment that impart mixed ionic and electronic conductivities to them. Since perovskite can accommodate all the elements in the periodic table they can offer excellent catalytic properties. The report is about the present status of perovskites based anode materials for SOFC application.
Mathematical Modeling of Cutting Force in Milling of Medium Density Fibreboard Using Response Surface Method
Authors: Raman Norazmein Abdul , Sharif Safian , Izman Sudin
Published: February 2012

This paper reports on the development of predicted mathematical model for cutting force (Fc) during side milling of medium density fiberboard (MDF) using uncoated carbide insert. Box-Behnken design (BBD) of experiment, coupled with response surface method (RSM) were employed to establish the cutting force model. Evaluation on the effects and interactions of the machining variables on the cutting force were carried out. The machining variables involved include spindle speed, feed rate, routing width and were denoted by A, B and C respectively. Statistical analysis conducted on the experimental results indicated that the mathematical model for cutting force was adequate within the limits of factors being investigated. After eliminating the insignificant factors or model terms in the reduced model, it was found that factors A, B, C, B2 (second order of B), C2 (second order of C), were the most significant factors affecting the cutting force. BC (interaction of B and C) and AC (interaction of A and C) are the subsequent significant factors. Three-dimensional plots displaying the interactions between these significant factors were presented. The reduced model was then verified experimentally and statistically using ANOVA. It was evident that Box-Behnken design proved to be an efficient tool in identifying and constructing maps of interactions between the significant factors. Experimental results showed that lower cutting force can be obtained by employing higher cutting speed, low feed rate and lower routing width when side milling MDF using uncoated carbide insert.
Processing and Thermal Conductivity Characterization of Solid Glass Micro-Spheres Filled Polymer Composites
Authors: Mishra Debasmita , Satapathy Alok , Patnaik Amar
Published: February 2012

This paper describes the preparation and thermal conductivity characterization of solid glass micro-spheres (SGMs) filled polymer composites. SGMs of different sizes are embedded in epoxy resin to develop composites by hand layup technique. A numerical simulation of the heat-transfer within the composites is made by using finite element method (FEM). Three-dimensional spheres-in-cube lattice array models are constructed to simulate the microstructure of composite materials for various SGM content ranging from 0 to about 27 vol % and the effective thermal conductivities (Keff) of the composites are estimated. Keff values are also calculated using some of the existing theoretical models. Finally, guarded heat flow meter test method is used to measure the conductivity of these composites. The simulations are compared with Keff values obtained from experiments and it is found that the FEM simulations are fairly close to the measured Keff. This study shows that the incorporation of SGMs results in reduction of conductivity of epoxy resin and thereby improves its thermal insulation capability. Further, the size and content of SGMs influence the extent of reduction of Keff. Keywords: Composites; Glass Microspheres; FEM; Thermal Conductivity; Simulation
Production of a Helicopter Tail Boom and Associated Mechanical Tests
Authors: Kavrar Deniz , Öveçoğlu M. Lutfy , Türkmen Halit S.
Published: February 2012

The lightweight materials such as composites are often used for the aerospace structures. One of the uses of these materials is for the tail boom of helicopters. Tail booms are the structures connecting the tail rotor to the fuselage. It is mainly subjected to the pitching moment and torsion. Because it is long to obtain the enough distance between the tail rotor and the main rotor, the materials used for manufacturing the tail boom needs to be a lightweight material. The structural optimization of the tail boom is also necessary. In this study, two different tail booms are manufactured by using laminated composites. The tail booms considered in this study are a semi-monocoque structure consisted of skins and stiffeners. These skins and stiffeners are made of carbon/epoxy. One is produced by using 3-ply carbon/epoxy and it is strengthened using stiffeners. The other is produced by using honeycomb between 2-layers of carbon/epoxy. A hand lay-up technique is used for the manufacturing of the tail booms. The vacuum bagging and a moderate heat are used to cure the composite structure. The bending and bending with torsion tests are performed to determine the structural performance of the tail booms. The tail boom is also modeled using the finite element method and analyses are performed. The results are presented and discussed.
Coupled Structural/Thermal Analysis of Cylindrical Part of Multilayered Composite Vessel
Authors: Hocine A. , Achira F.K. , Ghouaouala H.
Published: February 2012

This paper focuses on the coupled structural/thermal response of a cylindrical part of multi-layered composite vessel. Uniform and parabolic temperature distributions are chosen for the structural loads. In this work, an analytical model is proposed in which the laminate composite is assumed to be an anisotropic purely elastic material. Assuming that the interface between the core and skin are perfectly bound, continuity conditions for the displacement and stress, the suggested analytical model provides an exact solution for stresses and strains on the cylindrical section of the vessel solution submitted hygrothermal loading coupled with internal pressure with end effect.
Micro-Milling of Hardened AISI D2 Tool Steel
Authors: Saedon J.B. , Soo S.L. , Aspinwall D.K. , Barnacle A.
Published: February 2012

The paper presents an experimental investigation into the slotting of hardened AISI D2 (~62HRC) tool steel using 0.5mm diameter coated (TiAlN) tungsten carbide (WC) end mills. SEM analysis of tool morphology and coating integrity was undertaken on all tools prior to testing. Tool wear details are given based on resulting cutter diameter and slot width reduction. In addition, cutting forces are also presented together with details of workpiece burr formation. A full factorial experimental design was used with variation of cutting speed, feed rate and depth of cut, with results evaluated using analysis of variance (ANOVA) techniques. Parameter levels were chosen based on microscale milling best practice and results from preliminary testing. Main effects plots and percentage contribution ratios (PCR) are included for the main factors. Cutting speed was shown to have the greatest effect on tool wear (33% PCR). When operating at 50m/min cutting speed with a feed rate of 8µm/rev and a depth of cut of 55µm, cutter diameter showed a reduction of up to 82µm for a 520mm cut length. SEM micrographs of tool wear highlighted chipping / fracture as the primary wear mode with adhered workpiece material causing further attritious wear when machining was continued up to 2.6m cut length. All tests produced burrs on the top edges of the slots which varied in size / width to a lesser or greater degree. Under the most severe operating conditions, burr width varied from approximately 50µm to more than 220µm over the 520mm cut length. Cutting forces in general were less than 12N up to test cessation.
Thermal Stresses in Thick Walled Cylinders due to a Periodic Moving Heat Source: Effect of Material Properties
Authors: Alzaharnah Iyad T.
Published: February 2012

nternal heating of hollow cylinders with moving periodic heat source is examined in relation to surface treatment applications. This study includes three different cylinder materials, namely aluminum, nickel and titanium. Effective stresses in the cylinder wall are found to be mainly attributed to longitudinal temperature gradients. The aluminum cylinder shows sharper longitudinal temperature gradients as compared to the nickel and the titanium cylinders, which is due to the high value of the aluminum specific heat capacity. However, the larger Eα (elasticity modulus × thermal expansion coefficient) values for nickel cylinder result in higher levels of stress although nickel and titanium cylinders exhibit similar longitudinal temperature profiles. During dwelling time for the heating source at a certain spot, titanium cylinder exhibits lower levels of temperature increase as compared to aluminum and nickel cylinders, due to its lower value of thermal conductivity.
Influence of Process Parameters on the Mechanical Enhancement of Copper-DHP by FSP
Authors: Galvao Ivan , Loureiro Altino , Rodrigues Dulce Maria Esteves
Published: February 2012

Friction Stir Processing (FSP) is an innovative solid-state processing technology, which is being currently used to enhance locally the mechanical properties of conventional materials. In this work, 1 and 3 mm-thick copper-DHP plates were processed with the aim of simulating surface (SFSP) and bulk (VFSP) processing. The influence of the processing conditions on the microstructure and mechanical properties of the processed materials was analyzed. It was found that the tool geometry, which has a close relation with the plastic deformation and dynamic recrystallization kinetics inside the stirred volume, the processing parameters and the heat exchange conditions, which determine the extent of dynamic recrystallization and annealing phenomenon, are determinant in FSP.
The Influence of Major Defects on the Properties of Continuous Galvanized Steel Sheet
Authors: Azimi A. , Shahriari F. , Ashrafizadeh F. , Toroghinezhad M.R. , Jamshidi J.
Published: February 2012

Production of defect-free galvanized steel sheet is considered a major concern for automotive and other critical applications; nevertheless, the occurrence of some defects in the coated sheets is unavoidable. In order to alleviate the problem, we need to know the extent to which the properties of a galvanized sheet are influenced by the presence of a given defect. In this investigation, specimens including any of the two major defects of continuously galvanized steel sheets were selected from a large number of coated samples. The defects, including furnace roll pimples and bare spots, were microstructurally characterized and their influence on corrosion behaviour and mechanical properties of the steel sheet was evaluated. Corrosion resistance was examined via standard salt spray test and Tafel polarization. Tensile test was employed as a measure of mechanical properties of the defective galvanized sheets. The results indicated that the presence of defects had little influence on the tensile properties of the samples, but considerably reduced their corrosion resistance. Based on the results of salt spray tests, pimples reduced corrosion resistance of galvanized sheets 23 % (50 hours) on average and bare spot defects caused reduction in corrosion resistance up to 39%.
Morphological and Structural Properties of NbN Thin Films Deposited by Pulsed Laser Deposition
Authors: Farha Ashraf Hassan , Er Ali Oguz , Ufuktepe Yüksel , Elsayed-Ali Hani E.
Published: February 2012

Niobium nitride (NbN) films were deposited on Nb using pulsed laser deposition (PLD), and the effect of substrate deposition temperature on the preferred orientation, phase, and surface properties of NbN films were explored by x-ray diffraction (XRD) and atomic force microscopy (AFM). It was found that the substrate deposition temperature has a significant influence on properties of the NbN films, leading to a pronounced change in the preferred orientation of the crystal structure and the phase. We find that substrate temperature is a critical factor in determining the phase of the NbN films. For a substrate temperature of 650 °C 850 °C, the NbN film formed in the cubic δ-NbN phase mixed with the β-Nb2N hexagonal phase. With an increase in substrate temperature, NbN layers became β-Nb2N single phase. Essentially, films with a mainly β-Nb2N hexagonal phase were obtained at deposition temperatures above 850 °C. Surface roughness and crystallite sizes of the β-Nb2N hexagonal phase increased as the deposition temperatures increased.