International Journal of Materials and Product Technology (27 papers in press)
Multi-response optimization for MRR and Ra in WEDM process of Nimonic-263 super alloy
by Nasina Venkaiah, Maddina Sreenivasa Rao
Abstract: Nimonic-263 is a nickel based super alloy with exciting applications. Due to its high hardness and low thermal conductivity, wire electrical discharge machining (WEDM) has been selected to machine the material. To get the optimal performance level, the process parameters have to be set carefully. Furthermore, multi-objective optimization of WEDM process is too difficult as it involves several process parameters. Although there are several multi-response optimization techniques, industry is faced with a problem of choosing the best technique. The objective of the present work is, therefore, to apply different multi-response optimization techniques, which are easy to implement and involve less computational effort with a view to recommend best technique. Response surface methodology (RSM) has been used for experimental design. A comparative analysis among the optimization techniques is carried out. It has been observed that TOPSIS is found to be the best among different multi-response optimizations techniques chosen.
Keywords: WEDM; RSM; multi-response; Nimonic-263; optimization.
Theoretical procedure for the stress state assessment of hyper-static crankshafts
by Sergio Baragetti
Abstract: Crankshafts with many rods and crankpins for mechanical and industrial applications can be designed with first-order-approximation theoretical procedures in the literature. Numerical Boundary Element Method (BEM) or Finite Element Method (FEM) procedures can be used, with the latter models having a 3D tetrahedral wire beam of hexahedral finite elements. To the best of the authors knowledge, the literature does not contain accurate evaluations of hyper-static reactions at the restraints of a crankshaft with four crankpins and five supports. The principle of virtual work is implemented to allow calculation of the reactions at the bearings of the shaft and to determine the internal actions (bending, torsion, shear and axial force) for each section of the shaft. The developed procedure does not give better results than a numerical BEM or 3D FEM code, but it is less expensive and less time consuming when implemented in a mathematical commercial code. Furthermore, the procedure gives results that have a better approximation with respect to the theoretical literature models. The theoretical model was validated through comparison with the results of a finite-element linear beam model developed using a commercial FEM code.
Keywords: Four-rod crankshaft; Theoretical model; Machine design; Performance enhancement; Fatigue design.
Self-healing of self-compacting concretes made with blast furnace slag cements activated by crystalline admixture
by Emilio Takagi, Maryangela Lima, Paulo Helene, Ronaldo Medeiros-Junior
Abstract: Test samples were examined using a specific crystalline admixture, AR glass fiber and three types of cements with percentages of Blast Furnace Slag of 55%, 35% and 0%. Test specimens were loaded under compression until 90% of their failure load, in order to generate a network of micro-cracks. These samples were subsequently immersed in lime water to trigger the self-healing mechanism, followed by various tests at 28, 56 and 84 days. As BFS content ratio was increased to 55%, there was a noticeable increase in mechanical recovery and permeation reduction properties, indicating good self-healing.
Keywords: concrete structures; self-healing; materials technology; blast furnace slag; mechanical properties; permeation properties; cement; crystalline admixture; construction material; cracks.
Powder-materials impact on nanoparticle-reinforced Ti6Al4V matrix composites produced via Inductive Hot Pressing
by Isabel Montealegre Melendez, Erich Neubauer, Cristina Arévalo, Eva Perez-Soriano, Michael Kitzmantel
Abstract: This paper addresses the optimal manufacture of titanium alloy composites via inductive hot pressing, and studies the influence of nanosized reinforcement and matrix powders on the final properties of the titanium-based composites.
Before hot consolidation, two types of Ti-6Al-4V powders were mixed with various percentages of nano-diamonds. After inductive hot pressing at 900
Keywords: Titanium alloys; Nano-diamonds; Metal matrix composites; Inductive hot pressing.
On Rapid Prototyping of Assembly Systems A Modular Approach
by Zhiqin Qian, Tan Zhang, Wenjun Lin, W.J. Zhang
Abstract: This paper proposes a new product and manufacturing technology for rapid prototyping of product systems (RPPS). It is noted that a system in this paper is defined as a physical assembly that can be decomposed into components. The rapid prototyping is achieved by a novel modular concept, that is, the base materials to build a component as well as an assembly is highly modularized (the interface between any two modules are identical) and building a system is simply by assembling the modules. The rapid prototyping in this paper differs significantly from the rapid prototyping in literature in that the latter builds a system layer by layer and further primarily builds a component instead of assembly (building of an assembly is actually very limited with the latter, though possible). This paper explains the RPPS approach and presents a feasibility study on the RPPS technology. It has been shown that the RPPS technology is promising.
Keywords: Rapid prototyping of assembly; Evolutionary algorithm; Modular plastic module.
Application of genetic algorithm in optimization of cutting force of Al/SiCp metal matrix composite in end milling process
by Aezhisai Vallavi M S, Mohan Das Gandhi N, Velmurugan C
Abstract: This paper investigates the cutting force of LM6/SiCp using end milling process. Mathematical models have been developed to predict the cutting force in terms of spindle speed, axial depth of cut and weight percentage of SiCp. Response surface methodology has been employed to create the mathematical model. The experiments have been conducted on LM6/SiCp by carbide insert and cutting forces have been measured using a milling tool dynamometer. The direct and interaction effects are studied with the influence of machining parameters. Analysis of variance (ANOVA) has been used to check the adequacy of the model. Optimum combination can be attained for the best result.
Keywords: Cutting force; End milling; Metal Matrix Composite (MMC); Response surface methodology; Optimization.
A method to determine the forming limit for cross-section distortion of rectangular tube in rotary draw bending process
by Ning Guo, Kuanxin Liu, Shunqi Zheng, KeMin Xue, WenTao Huang
Abstract: In the manuscript, the forming limit for cross-section distortion is defined according to the employing area and aviation standard. First, the definition and determination method of forming limits is proposed. And then, the effects of process parameters on forming limit are investigated- based the 3D FE simulation model. It is found that with the increase of height, clearance between mandrel and tube, clearance between core and tube and the strengthen coefficient, the minimum bend radius increases and the bending limit decreases; with the increase of width and strain-hardening exponent, the minimum bending radius decreases and the bending limit increases. Finally, the 3D forming limit diagrams for cross-section distortion are obtained under different process parameters.
Keywords: Forming limit; minimum bending radius; cross-section distortion.
Experimental Modeling and Genetic Algorithm based Optimization of Friction Stir Welding Process Parameters for Joining of Dissimilar AA5083-O and AA6063-T6 Aluminum Alloys
by SAURABH KUMAR GUPTA, K.N. Pandey, Rajneesh Kumar
Abstract: The demand of joining of dissimilar aluminum alloys is increasing dayby-day in various industries. The defect free joining of aluminum alloys using conventional welding process is a difficult task for a manufacturer. Friction Stir Welding (FSW) is a solid state joining process and one of the most promising technique for defect free joining of aluminum alloys. In this paper, second order regression modeling and genetic algorithm based optimization of FSW process parameters is presented for joining of dissimilar AA5083-O and AA6063-T6 aluminum alloys. For developing the regression model, experiments were performed as per L27 orthogonal array of Taguchi methodology and models were developed with the help of MINITAB software. For genetic algorithm based process parameter optimization, developed regression models were considered as objective functions. The developed regression models have been found satisfactory for predicting the responses at 99% confidence level. The derived set of optimal process parameters were found as tool rotational speed of 900 rpm, welding speed of 60 mm/min, shoulder diameter of 18 mm and pin diameter of 5 mm for maximum tensile strength and minimum grain size. The significant process parameters and their effect on responses have also been determined and discussed.
Keywords: FSW; aluminum alloys; genetic algorithm; optimization; tensile strength; grain size;.
METHODOLOGY FOR DATABASE DEVELOPMENT FOR ELECTRO DISCHARGE BORING OF AEROSPACE MATERIAL
by Sudhanshu Kumar, Harshit K. Dave, Keyur P. Desai
Abstract: In the present investigation, boring of an aerospace material (Inconel 718) is performed on electro discharge machine. Boring operation of predrilled circular cavity is achieved using tool movement on radial path during EDM process. The actuation of tool electrode is guided and controlled in such a way that it moves on a radial path with an angular increment of 5 degree from previous path. Using Taguchi design of experiment and application of multiple regression equations, a database is generated for the selection of suitable combination of process parameters for boring operation in EDM process. The criterion of creating the database for proper selection of parameters is to minimize the overcut while maintaining the surface roughness within the specified range during boring operation. In this methodology, the parameters that have lesser influence on surface roughness are identified and then their levels are suitably chosen for minimum overcut generation. Remaining factors levels are varied in such a way that the surface roughness will remain within the specified range. This type of technological database will be very useful for application in future, as it will provide direct selection of appropriate combination of parameters for boring of Inconel 718 using EDM process.
Keywords: Boring; overcut; surface roughness; Inconel; radial tool movement; electro discharge machining.
Effect of TiO2 enriched fluxes on the bead geometry, grain size and hardness in Submerged Arc welds
by Joydeep Roy, Ram Naresh Rai, Subhashchandra Saha
Abstract: This work is mainly concerned about the influence of titanium dioxide powder addition into flux on the bead geometry, grain size, and hardness in submerged arc weld of low alloy steel plates. Titanium dioxide powders were mixed with the commercial fluxes in a different proportion of 2.5, 5, 7.5, 10 and 12.5%. The welding process parameters were kept constant for different welding conditions. Bead geometry parameters show a significant improvement due to the titanium dioxide addition. 5% of titanium dioxide enrichment was showing the best result for the bead geometry parameters. Nucleation of the acicular ferrite and grain refinement of weld metal (WM) microstructure has been observed with the enrichment of titanium. Average grain size of ferrite and pearlite decreases with the increase of titanium content. Phase analysis of weld metals shows that the ferrite% increased and pearlite% decreased with respect to titanium content. But the increase of titanium content was not showing any clear trend on the hardness profile of weldments.
Keywords: SAW; bead geometry; phase analysis; grain size; hardness.
An Experimental Study of Investigating the Relationships between Structures and Properties of Al Alloys Included with high Mg and high Ti
by Halil Ibrahim Kurt, Ibrahim H. Guzelbey, Serdar Salman
Abstract: In this study, the influences of high magnesium (Mg) and high titanium (Ti) additions on aluminum (Al) alloys were investigated to peruse the relationship between the structure and properties of the new alloys. Microstructural analyses were performed using X-ray diffraction (XRD), the polarized optical microscope, and scanning electron microscope (SEM) equipped with energy dispersive spectrometry (EDS). In the microstructure of the alloys, the β-phase (Al3M2) α-solid solution, Ti2Mg3Al18 and TiAl3 particles were revealed. Results showed that the average grain size of Al-Mg-Ti alloys was found to be different in each composition, and the smallest grain size was obtained at Al-12Mg-3Ti alloy as 88 μm. The highest tensile strength (170 MPa) was attained with additions of 8 wt.% Mg and 1 wt.% Ti, but the highest hardness value (125 HBN) was obtained with additions of 14 wt.% Mg and 3 wt.% Ti. It was noted that the smallest average grain size did not behave in accordance with the highest mechanical properties. For the work, the optimal ratios of magnesium and titanium entrained into Al alloys were 8 wt.%, and 1 wt.%, respectively.
Keywords: Ti and Mg additions; Al-Mg-Ti alloys; Microstructure; Mechanical and Physical Properties; Casting.
Analysis on Surface Characteristics of Electro-Discharge Machined Inconel 718
by Siba Sankar Mahapatra, Bibhuti Bhusan Biswal, Manoj Masanta, Rahul Kumar, Saurav Datta
Abstract: An experimental investigation has been conducted on Electro-Discharge Machining (EDM) of Inconel 718 using Copper electrode tool. Based on L25 Orthogonal Array, experiments have been conducted by utilizing five controllable process parameters (viz. gap voltage, peak current, pulse-on time, duty factor and flushing pressure), each varied at five discrete levels, within selected parametric domain. The following responses in relation to surface characteristics of EDMed Inconel 718 i.e. Roughness average (Ra), Surface Crack Density (SCD) and White Layer Thickness (WLT) have been investigated. SEM micro-graphs revealing irregularities in surface morphology of the EDMed Inconel 718 have been analysed in detail and correlated with the information obtained through EDAX, XRD and micro-hardness tests of the machined surface. Occurrence of different types of cracks within EDMed end product has been identified. Effects of significant process parameters on surface topography in terms of roughness average, surface crack density, extent of white layer etc. have been graphically represented. Finally, Utility theory in conjugation with Taguchis optimization philosophy has been attempted to select the most favourable process environment (parameters setting) to satisfy optimal Ra, SCD and WLT; thereby, ensuring high product quality along with its specified functional requirements in appropriate application domain.
Keywords: Electro-Discharge Machining (EDM); Inconel 718; Surface Crack Density (SCD); White Layer Thickness (WLT); Utility theory; Taguchi’s optimization philosophy.
Biomimetic application of non-smooth surface characteristic in anti-sticking drill stem
by Xiaofeng Yang, Re Xia, Hongwei Zhou, Lu Guo
Abstract: It is one of common phenomenon that the drill stem could be easily stuck in soft stratum, which consequently affects the drilling efficiency seriously. In this paper, a biomimetic method to relieve the sticking problem of the drill stem is presented and studied. The anti-sticky mechanism of the earthworm for its amazing burrowing in the soft soil is investigated and probed further, figuring out the fact that the corrugated surface structure of earthworm could reduce the friction assistance and soil adhesion. Inspired by earthworm, biomimetic drill stem with corrugated surface is designed and applied in the soft stratum drilling. The results show that compared with the conventional one, the novel biomimetic drill stem could effectively avoid being stuck in the soft stratum, and the torque and thrust of the biomimetic drill stem show a considerable decrease in the soft stratum drilling. The mechanism of its good anti-sticking ability in soft stratum drilling is addressed, and the effects of wavelength on both torque and thrust are investigated for experimental and industrial optimization.
Keywords: Non-smooth surface; earthworm; anti-sticking; friction; biomimetic drill stem.
Analysis of Dimensional Inaccuracies in square cavities generated on Ti-6Al-4V using Planetary EDM
by Vishal John Mathai, Harshit Dave, Keyur Desai
Abstract: Dimensional accuracy of features generated by Electro Discharge Machining (EDM) is influenced by process parameter combination as well as process instability. In present study an attempt has been made to study the effect of process parameters viz. pulse ON time, tool path offset, scanning speed, pulse OFF time and gap voltage on overcut, internal edge radius and achieved cavity depth during Planetary EDM of Ti-6Al-4V. Experimentations designed using Taguchis L′16 standard orthogonal array has been carried out using copper as well as graphite electrodes. Results suggest that for both electrode materials, pulse ON time have relatively high statistical significance on overcut (51.7 % and 34.9 %) and internal edge radius (76.7 % and 28.7%). However, cavity depth achieved is significantly affected by pulse ON time (15.7 % for copper and 40.9 % for graphite) as well as tool path offset (79.8% for copper and 33.2 % for graphite.
Keywords: Titanium; EDM; Overcut; Quality; Planetary; ANOVA.
Application and Anti-bacterial Performance Evaluation of Liquid Glass Coating
by Bingjie Xiao, Ayman Ibrahim, Xiao Huang, Rong Liu
Abstract: Liquid glass (LG) coating, supplied by Liquid Glass Shield Company, is capable of enhancing the wear resistance of surfaces without altering the surface features. Additionally, the coating contains ethanol that acts as an anti-microbial agent. In this study, LG is deposited on nickel substrate to investigate its ability to impede bacterial growth. The coating is applied using a spin coater and followed by a furnace curing process. The coating is then tested for bacterial growth through the deposition of a known type of bacteria onto the cured coating surface. The liquid glass coating has shown enhanced anti-bacterial ability when compared to bare nickel surface. However, the anti-bacterial ability of LG is slightly lower than that of brass alloys.
Keywords: liquid glass coating; anti-bacterial performance; E.coli; colony-forming unit; nickel; brass; benzalkonium chloride; sodium pyrithion.
Experimental and mathematical evaluation of thermal and tensile properties of friction stir welded joint
by Ratnesh Kumar, Bhabani Bora, Somnath Chattopadhyaya, Grzegorz Krolczyk, Sergej Hloch
Abstract: The aim of this experimental work is to develop a mathematical model of friction stir welded joint of aluminum alloy 6061-T6 for correlating the process parameters (rotational speed, welding speed) with output responses (Maximum Process Temperature, Yield Strength, Ultimate Tensile Strength and % Elongation).This developed model provides an empirical relationship between the modeled values and experimental values. Experiments of AA 6061-T6 FSW butt joint were carried out using the Full Factorial design of experiment. Analysis of variance and scatter diagram has been employed to assess the significant effect of the factors and the adequacy of the models developed for the response variables. The optimum values of output responses i.e. TMax, YS, UTS and % E are found as 417.98
Keywords: Friction Stir Welding; Full Factorial Design; ANOVA; Genetic Algorithm.
Experimental Design of a Folded-Structure Energy-Absorption System
by Haim Baruh, Elsayed Elsayed
Abstract: This paper describes the design and analysis of an energy-absorption-system container made of chevron-pattern folded paper for the purpose of encasing supplies to be dropped from moving aircraft without using a parachute. A mathematical model of the energy absorption system is developed. The constitutive properties of the system are ascertained experimentally, and the system is tested by dropping containers with different types of cargo and from different altitudes and aircraft speeds without a parachute.
Test results in a laboratory and actual drop tests from moving aircraft demonstrate that this energy-absorption system manufactured using the paper-folding machine, built at Rutgers University, absorbs the impact energy of the drop and protects the cargo from the collision forces that are encountered when the dropped container impacts the ground and tumbles. It is shown that the design can successfully protect items with different fragilities inside containers dropped from different altitudes up to 30 m with aircraft speeds up to 70 KIAS.
Keywords: folded structures; energy absorption; drop tests; constitutive properties; impact testing.
Multi-objectives optimization of PU foams on acoustic performance by using design of experiment
by Chen Shuming, Jiang Yang
Abstract: The main objective of this study was to obtain an optimal formulation of PU foams with improved acoustic properties by using design of experiment (DOE). With the aim to obtain an efficient acoustic material, the PU foams formulation can be optimized successfully by adjusting the content of various additive components in this experiment. The experiments were conducted with four controllable 3-level factors and two target objectives, and Taguchis orthogonal array L9(34) had been chosen. The various additive components were: water (3.8-4.8 part by weight), tri-ethanolamine (TEA, 2-3 part by weight), HCFC-141b (4-6 part by weight) and A33 (0.9-1.1 part by weight). Sound absorption coefficient and transmission loss were both chosen as target objectives. The best formulation that optimized the acoustic properties of PU foams were determined by analysis of variance (ANOVA). From the results, the most significant factor affecting the experimental design objectives was identified.
Keywords: Optimizaiton; orthogonal array; sound absorption coefficient; transmission loss;.
A comprehensive review of microstructure evolution during friction stir welding of aluminium to copper
by Tanmoy Medhi, Barnik Saha Roy, Subhash Chandra Saha
Abstract: The present review paper focuses on the various researches done in joining of aluminium and copper by friction stir welding (FSW). Being a solid state process, FSW has proven to efficiently join aluminium and copper which is extensively used in power generation, electrical and electronic industry. However, it is a challenge to achieve a good quality welded joint of aluminium and copper due to the difference in properties of both the materials. The present review paper comprehensively reports the study of microstructure and its evolution during the process. Also, an assessment of the formation of different intermetallic compounds (IMCs) during the process and the effect of various process parameters like rotational speed, tool traverse speed, the arrangement of base materials, offset and tool geometry on the IMCs and microstructure evolution is given.
Keywords: Friction stir welding; Aluminium; Copper; Microstructure; Intermetallic compounds.
On the improved mechanical properties of nanoclay reinforced ABS composite for Fused Deposition Modelling
by Vishal Francis, Prashant K. Jain
Abstract: Due to the restrictions imposed by the availability of materials in Fused Deposition Modelling process (FDM), the achieved mechanical properties of FDM parts are limited. This scarceness leads to a critical need for improving the mechanical properties of FDM parts. The incorporation of nanoclay can effectively improve the mechanical properties of polymeric materials used in FDM. The present study investigates the FDM of clay-based polymer nanocomposite and examines the effect of dual extrusion in part fabrication. Multiobjective optimization, grey relation based Taguchi technique was used to determine the optimal processing temperature and clay content. Mechanical characterisation was performed on the nanocomposite developed and hybrid parts fabricated by dual extrusion. Microstructure investigation was carried out to examine the interaction between nanofiller and polymer for the developed filament and to study the fracture surface morphology. Incorporation of nanoclay demonstrated significant improvement in tensile, modulus and compressive strength as 14.5%, 21% and 24% respectively. A substantial increase in modulus and compressive behaviour was observed in hybrid parts. Hybrid parts demonstrated an increase in modulus as 70%, 94.8% and 147.8% for transverse, boundary and longitudinal reinforcement respectively along with an increase in compressive strength. The microstructure examination revealed that nanocomposite parts have fewer voids compared to ABS specimens due to better neck formation between the rasters. The developed material possesses enhanced properties compared to the virgin polymer and can be used effectively as an alternative material for FDM process. Dual extrusion technique can aid to tailor material properties as per the requirements in FDM parts.
Keywords: Fused Deposition Modelling; Dual extrusion; nanoclay; nanocomposite; grey Taguchi method.
Determination of Heat Transfer Coefficients for Large Scale Steel Forgings Quenched in Polymer Solutions
by Jesús Mario Luna-González, Edgar Ivan Saldana-Garza, Rafael David Mercado-Solís, Luis Adolfo Leduc-Lezama, Bradley Wynne
Abstract: The inverse heat conduction method is used to calculate surface heat transfer coefficients (HTCs) as a function of temperature and location during quenching of a complex geometry large steel forging in a static polymer solution. Experimental temperature-time data extracted from the piece were used as input data to calculate the HTC. The geometry was divided into seven different zones (surfaces). An individual HTC, with a high level of experimental confidence, was calculated for each zone by using the inverse heat transfer module of the commercial software DEFORM 2D/3D. These HTCs were then used to predict the through thickness cooling behaviour of the component with a high degree of replication. This method thus appears be useful for further understanding the quenching process on large steel forgings, in general, but could be critical for obtaining accurate cooling behaviour in forgings with non-simple shapes, where one HTC may not be sufficient to describe local cooling behaviour.
Keywords: Inverse HEAT CONDUCTION PROBLEM; heat transfer coefficient; large scale forgings; quenching; polymer quenchant; computational simulation; quenching simulation; cooling curves; meshing; DEFORM 2D/3D.
Investigation into the Effectiveness of Cutting Parameters on Wear Regions of the Flank Wear Curve and Associated Cutting Tool Life Improvement
by Erhan Altan, Alper Uysal, Oguz Caliskan
Abstract: In machining operations, less tool wear and superior tool life are desired. Therefore, the effects of cutting parameters on tool life should be known and optimal cutting parameters should be chosen to reduce tool wear. In this study, the effectiveness values of cutting parameters on each wear region in the cutting tool flank wear curve were investigated to improve cutting tool service life. For this reason, some statistical methods were employed to determine them and the results were verified by experimental studies. The experiments were performed by turning of AISI 1040 carbon steel with uncoated WC (Tungsten Carbide) cutting tools at different cutting speeds, feeds and depths of cut. In the initial tool wear and the rapid tool wear regions, the most effective parameter was found as the feed and the tool wear increased with increase of the feed. In the steady-state tool wear region, the effectiveness values of the cutting speed and the feed were very close to each other, but the cutting speed was determined a little more effective. After the most effective cutting parameters on all tool wear regions were determined, validation experiments were conducted by considering these results to increase tool life during turning AISI 1040 carbon steel and AISI 4140 alloy steel. As a result, significant improvements on the tool life were obtained by properly choosing the cutting parameters for each cutting tool wear region.
Keywords: Tool life; Flank wear; Wear regions; Turning; Taguchi method.
Special Issue on: Recent Trends in Design of Nanocomposites Experimental and Theoretical Approaches
Analysis for electromagnetic performance of PM motor with different metal Nano-material bars
by Likun Wang
Abstract: With the appearance of high-performance permanent magnet (PM) materials as well as the development of computer technology and Nanotechnology and electricity machine theory, scholars have done a lot of research on the self-starting permanent magnet synchronous motor and have made many achievements. Although the starting permanent magnet synchronous motor has many advantages compared with the induction motor, there are also many problems. Since the self-starting motor needs to realize the self-starting and maintaining the synchronous speed operation, its rotor structure design is more complex. The rotor requires the starting winding and the magnets coexist, so there is "space competition", especially the small motors with high power density. Nowadays, Nano-materials are applied on a motor to improve its electromagnetic performance. In this paper, the electromagnetic performance of a PM motor with different metal Nano-material bars is researched by finite element analysis (FEA). In this paper, the electromagnetic performance of a PM motor is researched when the rotor bars are with different sizes metal Nano-palladium by FEA. The magnetic field distribution, the dynamic speed and torque variation, and the eddy current losses are analyzed respectively.
Keywords: permanent magnet materials; Nano-material; performance; synchronous motor.
Special Issue on: ModTech2016 Materials Science and Engineering Technologies
Re-Ranking In User-Driven Reputation Systems With Splay Tree
by Jayashree Ramakrishnan
Abstract: In e-learning environments, trust relationship plays a vital role in establishing collaborative activities among co-learners. Reputation is a fundamental source for measuring co-learners' trust. An efficient and effective way to construct trust relationship among faculties and students in e-learning environment is ranking. User-driven reputation systems are based only on the feedback or ratings provided by the users. Users with higher points obtain high rating compared to less scored users. Thus, by Zipf's law, alleged low users are pushed to the bottom of the ranking list. This condition is avoided by encouraging less likely users and preventing them from moving further down in ranking level. Low ranked users are provided with few more chances to participate actively in the e-learning environment. A splay tree is a Binary Search Tree with self-balancing skill. The splay tree brings the recently accessed item to the top of the tree. A splay tree is used to represent user's ranks, and low ranked users are semi-splayed again in the tree thus preventing them from further drowning in the ranking list for the fixed number of times. In this paper, we presented Rank_Improvement algorithm to enhance average scored users and compared with the ranking algorithm in the existing Question-Answering websites.
Keywords: Adaptive and intelligent educational systems; reputation management; user-driven reputation system; ranking using a splay tree; ranking algorithm; Question-Answering websites.
Recent status of overlay by plasma transferred arc welding technique
by Dhiraj Deshmukh, Vivek Kalyankar
Abstract: The aspects of investigation on surface characterization and role of material for various applications of petroleum, gas refineries, marine, aerospace, etc. have spurred in this era. The usefulness of surface protection techniques, materials, their performances and characteristics for particular medium is important to study, as it is vital to employ a specific required material for particular application. Considering these features, this manuscript presents the overview of plasma transferred arc welding technique used for the surfacing of parts. The main aim is to focus the investigations carried out from last decade based on tribo-corrosion performance of overlay surfaces and their key observations. In addition, the material combination, effects of process parameters, cause and effect diagram, microstructural benefits, common advantages and drawbacks associated with the technique are also presented. This will be beneficial to find out the main targeting areas by establishing a theoretical and technical bias for new research and industrial people.
Keywords: Surface modification; Plasma transferred arc welding; Overlay; Erosion-corrosion; Wear; Abrasion.
An Investigation on the Tensile Properties and Micro-structure of Hybrid Metal Matrix Composites
by VellingirI Suresh, N. Hariharan, S. Vellingiri
Abstract: In recent years, Aluminium Metal Matrix Composites (AMMCs) have emerged as a promising high class of materials. Metal matrix composites are emerging as very promising materials especially in the fields of aerospace, electrical, electronics and automotive for their various applications and technical demanding properties. In the present work, a brave is consummate to prepare and compare the tensile properties of LM25-Gr & LM25-Graphite /Boron carbide (B4C) hybrid composites. The composites were primed to make use of stir casting process in which quantity of reinforcement is speckled from 4 wt% of Gr and 3 wt% of B4C. The prepared composites are characterized by micro-structural studies and tensile properties were estimated as per the standards. The microphotographs of the composites revealed the reasonably homogeneous supply of the particles in composites with a group at a small number of places. The dispersed Graphite and B4C in LM25 alloy contributed in enhancing the tensile strength of the composites. The SEM of the illustration specifies the homogeneous supply of the reinforcement particles in the matrix without any annulled.
Keywords: Metal matrix composites; Aluminium alloy LM25; Tensile strength;B4C;Gr;SEM;Stir Casting; Micro-structure.
APPLICATION SUPPORTING THE PROCESS OF MANUFACTURING MODULAR CONSTRUCTION
by Rafał Rząsiński
Abstract: The basic concept described in this paper is the application that enables to generate technological data for machine design series of types. The data is generated in the traditional form (operation and instruction sheets) and codes for numerically controlled machine tools. The model of transformation is based on the developed theory of technological similarity using relational databases. The theory of similarity is based on the theory of physical similarity (Gendarz, P. 2002; Rzasinski, R 2015). The model in the theory of similarity of construction and technology is the construction and technology standard. An elaborated program based on the theory of construction and technological similarities supports the process of creating technological documentation. It is also possible to generate the NC (Numerical Control) code for the numerically controlled machine tools.
Keywords: technology; computer programms; modular series; databases.