bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and Performance of Photocatalytic GaN Powders
Authors: Nakano Takayuki , Hamada Masateru , Fuke Shunro
Published: April 2011

Group-III nitrides are expected to be used in future photocatalytic materials. InGaN is expected to be used for photocatalytic applications in the visible light region. Photocatalytic materials are used primarily in coatings and powders, and powdered photocatalysts are expected to be formed from group-III nitride powders. In this study, we produced GaN powders by nitriding Ga precursors at high temperatures under an atmosphere of NH3. The photocatalytic characteristics of the GaN powder were dependent on nitrization temperature. In addition, the crystallinity of the GaN powders and the photocatalysis were rapidly improved at nitrization temperatures over 1000°C.
Process Analysis of Laser Welding Method with Polybutyleneterephthalate (PBT)
Authors: Okuizumi Ryo , Hirota Shinichi , Takagi Youhei , Sudoh Masao , Okano Yasunori
Published: April 2011

The present study introduces the use of absorption energy as a parameter in thermal diffusion for explaining and predicting experimental results in laser welding. The developed parameter was utilized for the welding experiments of polybutyleneterephthalate (PBT). It was found that maximum welding strength values lie almost in the same range of absorption energy values for all cap thickness and scan velocity values considered in this work. One may then conclude that the absorption energy in thermal diffusion is an essential parameter for predicting experimental results in laser welding.
High-Efficiency SOI Photodetector Utilizing Surface Plasmon Resonance in Gold Corrugated Structure
Authors: Ono Atsushi , Satoh Hiroaki , Inokawa Hiroshi
Published: April 2011

We have investigated the absorption spectra of silicon-on-insulator (SOI) photodiode with Au thin film which is corrugated by SiO2 line-and-space structure. It is aimed for the high-efficiency of SOI absorption by surface plasmon resonance. The structural parameters such as SiO2 thickness, period of corrugation, and the duty-ratio were optimized by FDTD simulation.
Self-Organization Processes of Nanostructure Formation by Laser Radiation in Metal
Authors: Fedorenko L.
Published: April 2011

The current state of knowledge about mechanisms of metal nano-particles (NP) formation processes induced by the interaction of high-energy laser beam with surface of the metallic lattices (Au, Ag, Cu) is presented. The review includes an evaluation of the contribution of self-organized effects into the processes of the metal nano-structurization depending on the laser mode, external factors and internal parameters of an active zone. It was noticed that intensive pulsed laser illumination enabled to stimulate nano-fragmentation at the fluencies near and above the melting threshold of the metal in different mediums The laser induced processes of metallic particles formation by ablation of the metal target with consequent NP sizes stabilization by precise temperature tuning in the active zone, local plasmon resonance in liquids, and microablation mechanism in metal films in the conditions of surface plasmon resonance (SPR) due to self-organization effects are considered. Comparative analysis of the laser nano-technologies in air, vacuum, rarefied gas and liquid environments showed the advantages of self-organization in NP generation processes based on the SPR effects and their perspectives.
Coulomb-Coupled, Protein-Based Computing Arrays
Authors: Rakos Balázs
Published: April 2011

The present work continues the exploration of the potential advantages of proteins in Coulomb-coupled, molecular logic arrays by extending our previous study [1]. We show through simulations that the utilization of certain advantageous potential energy curve arrangements provides an alternative means for the realization of protein chains suitable for digital signal propagation, and universal logic gates.
Detection of the Nanostructures in ZnO Thin Films by Using Optical Methods
Authors: Rakov Mykhailo , Poperenko Leonid V. , Yurgelevich Iryna V.
Published: April 2011

The ZnO films deposited by reactive magnetron sputtering are investigated. SEM provides information on the composition of the films and enables us to observe the nanostructures. AFM provides information on the roughness and the texture of the surfaces. Fourier transform, photoluminescence and Raman scattering are used for confirmation of appropriate results. The spectral dependences of ellipsometric parameters Δ and Ψ are determined by ellipsometry and the effective values of optical constants n and k are calculated. As it can be indicated, the nanostructures in ZnO film are formed when reducing base pressure down to 2.5•10-7 mbar and elevating the temperature of the substrate up to 5500C. The amorphous structure is formed in most of other films (crystalline structure is formed at rather special conditions). Films containing considerable portions of impurities (generally carbon impurities) are formed at reduced base pressure. The values of optical constants of some of the films fit the appropriate Dumont and Jellison tabulations satisfactorily.
Development of Microclimate Regulatory Clothes
Authors: Šahta Ingrida , Baltina Ilze , Blums Juris
Published: April 2011

The research is dedicated to microclimate regulatory clothes with an integrated electrical system, which also composes Peltier elements, and cooling function is based on the heat conductivity in solids. For development of the system and the clothes experiments are conducted to optimize the product microclimate regulatory function.
Si-Based Single-Dopant Atom Devices
Authors: Tabe Michiharu , Moraru Daniel , Udhiarto Arief , Miki Sakito , Anwar Miftahul , Kawai Yuya , Mizuno Takeshi
Published: April 2011

We have recently proposed and demonstrated a new device concept, “Si-based single-dopant atom device”, consisting of only one or a few dopant atoms in the channel of Si field-effect transistors. The device characteristics are determined by a dopant, which is mediating electron or hole transport between source and drain electrodes. In this paper, our recent results on electronic and photonic applications are introduced. Furthermore, single-dopant images obtained by a scanning probe microscope are also presented.
Random Error in Intensity Spectrum Measured with THz-TDS - No Relation to the Intensity Fluctuation of Fs-Laser
Authors: Takeda Masanori , Tripathi Saroj R. , Aoki Makoto , Hiromoto Norihisa
Published: April 2011

We explored sources of random errors in intensity spectra measured with THz-TDS. Influences of detection accuracies, optical-delay scanning, atmospheric absorption, and intensity fluctuations of fs-laser on the detected THz pulses are discussed based on the standard deviations of measurement data. Those influences on the THz pulses are considerably small and not a predominant cause of the random error.
Physics of Flexible Magnetic Filaments
Authors: Javaitis Ivars , Zilgalve Vineta
Published: April 2011

A model of elastic magnetic filaments is developed, which allows investigating the dependence of filament dynamics on such physical parameters as magnetoelastic number (Cm), frequency of magnetic field, coefficient of friction, etc. By numerical simulation of the dynamics of filament shaping under the action of magnetic field it is shown that a characteristic U-like stable shape (hairpins) can form. Such a shape of filament can exist in the case of low-frequency rotating magnetic field. At the frequency increasing the U-like shape transforms to the S-like one. In the present work it is shown that in unsteady magnetic field a flexible magnetic filament “swims” in the direction of magnetic field.
Optical Properties of CaYAlO4: Eu3+ Phosphors
Authors: Bartic Marilena , Kominami Hiroko , Nakanishi Yoichiro , Hara Kazuhiko
Published: April 2011

CaYAlO4:Eu3+ phosphors have been synthesized by a solid state method, and characterized by X-ray powder diffraction and photoluminescence (PL). Under the excitation of 147 nm, the synthesized phosphors indicated PL characteristics of the Eu3+ center with the main emission peak at a wavelength of 611.5 nm. The emission intensity depended on synthesis temperature and Eu3+ doping concentration. The highest PL intensity was found for the Ca0.97Eu0.03YAlO4 synthesized at 1400°C for 2 h.
Sol-Gel Derived Ferrites: Synthesis and Characterization
Authors: Gatelyte Aurelija , Jasaitis Darius , Beganskiene Aldona , Kareiva Aivaras
Published: April 2011

In the present work, the sinterability and formation of nanosized yttrium iron garnet (Y3Fe5O12), yttrium perovskite ferrite (YFeO3), cobalt, nickel and zinc iron spinel (CoFe2O4, NiFe2O4 and ZnFe2O4, respectively) powders by an aqueous sol-gel processes are investigated. The phase purity of synthesized nano-compounds was characterized by powder X-ray diffraction analysis (XRD). The microstructural evolution and morphological features of obtained transition metal ferrites were studied by scanning electron microscopy (SEM). The possible application of these nanosized transition metal ferrites as ceramic pigments was demonstrated.
Comparison of Biphasic Calcium Phosphate Bioceramics Fabricated Using Different Techniques
Authors: Salma Kristine , Irbe Zilgma , Jakovlevs Dmitrijs , Borodajenko Natalija , Berzina-Cimdina Liga
Published: April 2011

In this work three different preparation techniques of biphasic calcium phosphate (BCP) bioceramics (consisting of both hydroxyapatite (HAp) and β-tricalcium phosphate (TCP)) are compared: sintering of synthetic calcium-deficient apatites (CDAs) (intimate mixture of HAp and TCP - SBCP), sintering of mechanical mixture of synthetic HAp and apatitic tricalcium phosphate (Ap-TCP) - MBCP and sintering of mechanical mixture of synthetic HAp and calcium metaphosphate glass (CMG) - GBCP. Two different HAp/TCP phase ratios were investigated: 20/80 and 60/40. Phase composition, microstructure, sintering properties and microporosity of obtained BCP bioceramics were investigated. The open porosity of prepared BCP bioceramics is strongly influenced by phase composition and preparation technique. BCP bioceramics SBCP and MBCP have homogeneous microstructure, whereas GBCP has inhomogeneous inclusions of dense TCP. High content of hydroxyapatite (HAp) phase in MBCP and SBCP correlates with high microporosity.
Effect of Cooling Conditions on Nano-Sized NiFe2O4 Electrical Properties
Authors: Sutka Andris , Mezinskis Gundars , Lagzdina Santa , Bebris Gatis
Published: April 2011

Nickel ferrite NiFe2O4 nanoparticles have been prepared by sol-gel auto combustion. Two groups of samples were obtained from as-burnt and calcined powders by using various cooling conditions. The X-Ray diffraction (XRD) analyses confirm the single phase spinel structure for all samples. The grain sizes investigated by scanning electron microscopy (SEM) were found within the range of 70-100 nm. DC resistivities for different group of samples are strongly affected by cooling rate, showing the way how to control NiF2O4 electrical properties.
Synthesis and Properties of New Glassy Molecular and Oligomer Azocompounds Suitable for Holographic Recordings
Authors: Traskovskis Kaspars , Kokars Valdis , Ozols Andris , Augustovs Peteris
Published: April 2011

Molecular diphenylamine derivative containing two azochromophores has been synthesized. Compound showed formation of stable amorphous glassy phase with good optical quality. Functionalization with bulky trityl- group was carried to further improve physical properties of material. Two types of azochromophore containing polymeric materials, azochromophore in side chain containing aromatic polyether and azochromophores in both, main and side chain, containing polyester were also synthesized. Samples for holographic recording were prepared using spin coating technique from saturated chloroform solution. Holographic recording experiments have been made using 532 and 633 nm lasers. All compounds showed ability of forming laser induced diffraction gratings.
Nonlinear Optical Susceptibility of Tetragonal BaTiO3
Authors: Gulbis Arnis
Published: April 2011

In the framework of the vibronic theory of ferroelectricity for the transparency region of tetragonal BaTiO3 components and of nonlinear optical susceptibility responsible for the second harmonic generation and the optical rectification are calculated. Selection rules for dipole transitions in the Γ point of the first Brilouin zone are extended over the whole zone. Calculations are confined to lowest order in expansion of susceptibilities in power series of low symmetry lattice distortion. Numerical values of susceptibilities have experimentally observed order of magnitude. The spectral behavior of and is calculated as well.
Investigation of the Mechanism of Polar Excitations on Frog Sciatic Nerve by Optical Stimulation
Authors: Hirayama Yuya , Ishizuka Satoru , Grigorievich Zimin Lev , Yamakawa Takeshi , Yamakawa Toshitaka
Published: April 2011

We observed nerve excitations on bullfrog sciatic nerves by an optical stimulation using a Holmium YAG (Ho:YAG) laser with the laser power over 2.0 [W]. The laser power was higher the amplitude of the action potential was bigger. However, when the laser power over 10.0 [W], the laser gave damage to the sciatic nerve and the action potential decreased. Not only the action potential was evoked by the high temperature but also the sciatic nerve was damaged by an overlarge temperature. These results show the possibility that the single wavelength laser can use to position estimation of epileptogenic focus and irreversible blocking of propagation of epilepsy seizure.
Development of Combined Treatment of Electro-Coagulation and Flocculation for Various Types of Wastewater
Authors: Matsuda Satoshi , Wada Takahiro , Suzuki Akiko , Suzuki Toshinori
Published: April 2011

This study aims at developing a new type of purification process for wastewater including suspended solids. The process consists of electrolysis and flocculation treatment (= electro-coagulation). Electrolysis was performed by applying direct current using parallel plate aluminum electrodes, and the optimal conditions were decided experimentally. The validity, as well as the purification mechanism of the process, was researched by measuring turbidity and TOC of the samples. Excellent results were obtained from treating tests for various wastewaters with different characteristics. It was suggested that colloid of aluminum hydroxide was formed by electrolysis treatment, meaning that the formation of colloid would be essential for this electro-coagulation separation. The research for aggregating agent suitable for this process was also carried out, but the best suited one was not found out because the results of flocculation test were very complicated.
Low Temperature Plasma Treatment for Immobilization of Biomaterials on Polymer Surface
Authors: Ogino Akihisa , Noguchi Suguru , Nagatsu Masaaki
Published: April 2011

In some medical use, surface property such as biocompatibility and blood compatibility is very important. To improve the surface property of polymers, ammonia plasma was used to introduce amino group onto polymer surface in order to bind with heparin. The amount and the selectivity of amino group were improved by plasma treatment. The ratio of sulfur contained in heparin to carbon also increased from 0.5% to 10% by plasma process. The positive correlation can be found between heparin immobilization and amino group introduced by plasma. The immobilized heparin is strongly connected and it enhances the anticoagulant property on the surface.
Simultaneous Determination of Absorption Coefficients for Skin and Muscle Tissues Using Spatially Resolved Measurements
Authors: Suzuki Hiroshi , Niwayama Masatsugu , Yamakawa Toshitaka , Ohkubo Masaki , Kime Ryotaro , Katsumura Toshihito
Published: April 2011

We present a method for simultaneous measurement of optical absorption coefficients for skin (μas) and muscle (μam) tissues using spatially resolved near-infrared spectroscopy (SRS). A novel calculation algorithm was developed to determine the absorption coefficients of superficial and deep layers within a three-layered structure using Monte Carlo simulation. A method for measuring the skin and muscle absorption coefficients was proposed based on this algorithm. In vitro experiments with tissue-like phantom and in vivo tests were performed using the SRS system with four separate detectors. The results show that the absorption coefficients for both skin and muscle tissues were obtained accurately.
Laser-Induced Doping of CdTe Crystals in Different Environments
Authors: Gnatyuk Volodymyr A. , Levytskyi Sergiy N. , Vlasenko Oleksandr I. , Aoki Toru
Published: April 2011

Different procedures of laser-induced doping of the surface region of semi-insulating CdTe semiconductor are discussed. CdTe crystals pre-coated with an In dopant film were subjected to irradiation with nanosecond laser pulses in different environments (vacuum, gas or water). The dopant self-compensation phenomenon was overcome under laser action and In impurity with high concentration was introduced in a thin surface layer of CdTe. In the case of a thick (300-400 nm) In dopant film, laser-induced shock wave action has been considered as the mechanism of solid-phase doping. Formed In/CdTe/Au diode structures showed high rectification depending on the fabrication procedure. Diodes with low leakage current were sensitive to high energy radiation.
Alarm System Design Based on Cause-Effect Model
Authors: Onishi Satoshi , Takeda Kazuhiro
Published: April 2011

Recently in U.S. and Europe, the approach for the safety of plant intensifies because of many accidents in plant. In the　approaches, alarm system is especially important. Alarms should be used to enable operators to diagnose faults of plant and plan countermeasures. To accomplish these functions, nuisance alarms should be eliminated. In this study, we suggest a systematic method of alarm system design for unsteady state process by using Cause-Effect model. The presumed indicators were chosen from intended indicators are theoretically guaranteed to be able to qualitatively distinguish all assumed faults. And by use of the different model for each process in unsteady state operation, it is considered that fault candidates and indicators are restricted. The method is applied to a simple process for the case study.
Telemanipulation without Physical Contact in the Intelligent Space
Authors: Takarics Béla , Sziebig Gábor , Korondi Péter
Published: April 2011

This paper presents a telemanipulation system, where the operator's movement is transmitted to the slave site not in a mechanical way, as in case of a real master device, but by image processing. The virtual master device uses cameras as sensors, subtracts the background from the images, and recognizes the skin colour of the operator in real time. The 3D position of the operator's hand is determined by stereo vision and it becomes traceable by the colour of the skin.
Multiple-Camera Optical Glyph Tracking
Authors: Pallos Tamás , Sziebig Gábor , Korondi Péter , Solvang Bjørn
Published: April 2011

The Optical Glyph Tracking technology utilizes image processing and pattern recognition methods to calculate a given object’s position and orientation in the three dimensional space. Cost, precision and reliability are the key aspects when designing such a tracking system. The advantage of optical tracking is that even the simplest cameras can be used to follow the object, and it requires only a single marker. In this paper support for multiple cameras is introduced. All cameras recognize a set of markers on their images and the calculated coordinates are averaged to get a global value. Also multiple different markers are placed on the tracked objects and when even one of them is recognized, the coordinates of the object can be calculated. The Optical Glyph Tracking is implemented as a standalone module and could be used as an input device for any kind of application.
Suitable Truncation of Room Impulse Response for Inverse Filter Design of Sound Reproduction System
Authors: Tatekura Yosuke , Honda Yusuke , Nakai Takayoshi
Published: April 2011

This paper introduces an automatic decision method for designing parameters of inverse filters to simplify realization of a high-performance sound reproduction system. The reproduced performance depends on several design parameters of the inverse filters that cancel the effect of room transfer functions (RTFs). Therefore, a method of determining the sample lengths of impulse responses of RTFs is proposed. In the proposed method, a suitable sample length of the impulse response is determined based on autocorrelation function (ACF) . The results of numerical simulations using real data reveal that the proposed method can determine suitable sample lengths while maintaining reproduction performance.
Anytime Fuzzy Modeling
Authors: Várkonyi-Kóczy Annamária R.
Published: April 2011

Nowadays practical solutions of engineering problems involve model-integrated computing. Due to their flexibility, robustness, and easy interpretability, the application of fuzzy models, may have an exceptional role. Despite of their advantages, the usage is still limited by their exponentially increasing computational complexity. Although, combining fuzzy and anytime techniques it becomes possible to cope with the available, usually imperfect or even missing information, the dynamically changing, possibly insufficient amount of resources and reaction time. In this paper, possibilities offered by (Higher Order) Singular Value Decomposition ((HO)SVD) based anytime fuzzy models are analyzed. A modeling methodology is suggested, which offers a way for both complexity reduction and improvement of the accuracy without complexity explosion thus coping with the temporarily available amount of information and (finite) time/resources and finding the balance between accuracy and complexity.
Propagator Method for Numerical Solution of Convective Fisher Equation
Authors: Zaime Daiga , Rimshans Janis S. , Guseynov Sharif E.
Published: April 2011

Propagator numerical method was developed as an effective tool for modeling of linear advective dispersive reactive (ADR) processes [1]. In this work implicit propagator difference scheme for Fisher equation with nonlinear convection (convective Fisher equation) is elaborated. Our difference scheme has truncation errors of the second order in space and of the first order in time. Iteration process for implicit difference scheme is proposed by introducing forcing terms in the left and right sides of the difference equation. Convergence and stability criterions for the elaborated implicit propagator difference scheme are obtained.
High-Resolution X-Ray Computed Tomography for Materials Research
Authors: Egbert André , Brunke Oliver
Published: April 2011

Nowadays, X-ray tube-based high-resolution CT systems are widely used in scientific research and industrial applications. But the potential, convenience and economy of these lab systems is often underestimated. The present paper shows the comparison of sophisticated conventional µCT with synchrotron radiation-based µCT (SRµCT). The tube-based µCT measurements were performed with a granite-based phoenix nanotom®-CT system (GE Sensing & Inspection Technologies, Wunstorf, Germany) equipped with a 180 kV, 15 W high-power nanofocus tube with tungsten or molybdenum targets. This X-ray tube opens a wide range of applications from scanning low absorbing samples in nanofocus mode with voxel sizes below 500 nm to scanning highly absorbing objects in the high power mode with focal spot and voxel sizes of a few microns. The SRµCT measurements were carried out with the absorption contrast set-up at the beamlines W 2 and BW 2 at HASYLAB/DESY, operated by the GKSS Research Centre.
Separation of Particles Employing Travelling-Wave Electrokinetic Phenomena and Inclined Gravity
Authors: Eguchi Masanori , Yamakawa Toshitaka , Yamakawa Takeshi
Published: April 2011

In travelling-wave electric fields, particles are propelled along electrode arrays by a propulsion force. The propulsion force depends on an applied frequency, voltage and size of particles. In this paper, we present the separation method of micro particles using the propulsion force and inclined gravity. The suspensions of polystyrene beads were used as the method to demonstrate the general application for the selective retention or transportation of particles. The efficiency of the method depends on the size of particles and mass density of particles. Additionally the method can measure the propulsion force on particles by adjusting the inclined angle.
A New System for Real Time Measurement of Nano- and Micro Particles in Flowing Gas. Design and Calibration.
Authors: Jabłoński Ryszard , Nowak Roland
Published: April 2011

The paper presents the method, configuration and calibration of special system for measuring the size of particles. It is designed for real-time measurement of particles in the range up to 10µm, moving with velocity up to 15m/s and under pressure up to 20 bar. The method is based on measuring light scattered by single particle. We focused on studying the output from photomultiplier and finding relationships between pulse shape and particle size, and also the time intervals between pulses.
Analytical Model of Chip Formation in Case of Orthogonal Cutting Processes
Authors: Salvatore Ferdinando , Mabrouki Tarek , Hamdi Hédi
Published: April 2011

The present work deals with the presentation of analytical methodology allowing the modeling of chip formation. For that a “decomposition approach”, based on assuming that the material removal is the summation of two contributions, ploughing and pure cut was adopted. Moreover, this analytical model was calibrated by a finite element model and experimental data in terms of temperature and applied forces evolutions. The global aim is to propose to the industrial community, an efficient rapid-execution analytical model concerning the material removal in the case of an orthogonal cutting process.
Numerical Model for Prediction of Cutting Force in Peripheral Milling Process Including Thrust and Tangential Damping
Authors: Mehdi Kamel , Zghal Ali
Published: April 2011

A numerical model for prediction of cutting force components in peripheral milling process, including the cutting process damping, is proposed. The cutting process damping creates two components (thrust and tangential) of a dynamic cutting force. The total force model is obtained through numerical integration of the local forces. The effects of tool parameters (diameter, helix angle, number of teeth) on process damping and cutting force distributions are discussed. It is shown that the average value of the process damping and the amplitude of the cutting force increase with increasing the tool diameter. On the other hand, when the tool helix angle increases the process damping increases and the cutting force decreases. The number of tool teeth’s has not an influence on the variation of the damping process and cutting force but an influence on the number of cycles of the periodic cutting process.
3D FEM Model for the Prediction of Chip Breakage
Authors: Klocke Fritz , Lung Dieter , Essig Christoph
Published: April 2011

The aim of the presented work was to define a criterion for the prediction of chip breakage in turning C45E+N (AISI 1045). The chip formation, the chip flow and the expansion of the chip due to collision with the periphery were modelled three-dimensionally using the Finite Element Method (FEM). The mechanical loads in the chip breakage zone were determined by comparing the modelled chip with high speed filming records of the real chip breakage cycle. Based on the calculated loads in the chip breakage zone a novel damage criterion based on an approach of Johnson and Cook was developed. This criterion enables the FEM-model to simulate chip breakage three-dimensionally for different tool geometries and varying cutting parameters. The enhanced FE model correlated well with high speed filming records of the chip flow and breakage as well as with the empirical determined cutting forces and chip temperatures.
A Numerical and Experimental Investigation of the Deformation Zones and the Corresponding Cutting Forces in Orthogonal Cutting
Authors: Agmell Mathias , Ahadi Aylin , Ståhl Jan Eric
Published: April 2011

This study are focused on the deformation zones occurring in the work piece in a machining process and the corresponding cutting forces. The fully coupled thermo-mechanical FE-model for orthogonal cutting, developed in [1] is utilized. The work piece material is modeled with Johnson-Cook plasticity including damage formulation. Simulations for different feed depths were performed. The cutting forces, the chip thickness ratio and the deformation widths were determined experimentally by the quick-stop images and a force measurements. The results from the simulations have been compared to experimental data for the cutting forces and the chip thickness ratio as a function of the theoretical chip thickness.
Energy Efficient Process Planning Based on Numerical Simulations
Authors: Neugebauer Reimund , Hochmuth Carsten , Schmidt Gerhard , Dix Martin
Published: April 2011

The main goal of energy-efficient manufacturing is to generate products with maximum value-added at minimum energy consumption. To this end, in metal cutting processes, it is necessary to reduce the specific cutting energy while, at the same time, precision requirements have to be ensured. Precision is critical in metal cutting processes because they often constitute the final stages of metalworking chains. This paper presents a method for the planning of energy-efficient machining processes based on numerical simulations. It encompasses two levels of planning flexibility: process adjustment and process design. At the process adjustment level, within the constraints of existing machines and tools, numerical simulations of orthogonal cutting are used to determine cutting parameters for increased energy efficiency. In this case, the model encompasses specific cutting energy, tool wear, chip geometry, and burr shape. These factors determine the energy and resources required for the chip formation itself, tool replacements, cleaning and deburring and with that the overall energy efficiency and precision. In the context of process design, with the ability to select machines, machine configurations, tools, and cooling systems, numerical simulations of cutting processes that incorporate machine and tool conditions are applied in the planning of energy-efficient machining. The method is demonstrated for the case of drilling processes and supported by experimental investigations that identify the main influences on energy efficiency in drilling.
Input Data for the Numerical Simulation of Metal Cutting
Authors: Rosa Pedro A. R. , Cristino Valentino A. M. , Silva Carlos , Martins Paulo A.F.
Published: April 2011

This paper is focused on the fundamentals of metal cutting and is aimed at enabling the readers to recognize the validity of test calibration procedures, to identify the possible sources of modelling errors and to understand the routes to improve the overall accuracy and reliability of physical, tribological and mechanical input data for the numerical simulation of metal cutting processes. Innovative testing equipments, experimental methodologies and numerical procedures developed by the authors give support to the presentation.
New Thermal Issues on the Modelling of Tool-Workpiece Interaction: Application to Dry Cutting of AISI 1045 Steel
Authors: Courbon Cédric , Mabrouki Tarek , Rech Joël , Mazuyer Denis , D'Eramo Enrico
Published: April 2011

The present work proposes to enhance the thermal interface denition in Finite Element (FE) simulations of machining. A user subroutine has been developed in Abaqus/Explicit © to implement a new experimentally-based heat partition model extracted from tribological tests. A 2D Arbitrary-Lagragian-Eulerian (ALE) approach is employed to simulate dry orthogonal cutting of AISI 1045 steel with coated carbide inserts. Simulation results are compared to experimental ones over a whole range of cutting speeds and feed rates in terms of average cutting forces, chip thickness, tool chip contact length and heat flux. This study emphasizes that heat transfer and temperature distribution in the cutting tool are drastically in uenced by the thermal formulation used at the interface. Consistency of the numerical results such as heat flux transmitted to the tool, peak temperature as well as hot spot location can be denitively improved.
Calibration of the Rheological Model Considering the Temperature in Milling Operation of Ti-6Al-4V: a Preliminary Analysis
Authors: Pittalà Gaetano M. , Monno Michele
Published: April 2011

The machining of titanium alloys is critical also because of high temperature reached at the tool nose. The temperature of the cutting tool affects the tool life and, in order to decrease the temperature, cutting speed is reduced. The prediction of temperature can allow designing the cutting process, in terms of cutting parameters, or make the best selection of the cutting tool, with reduced experimental effort. The rheological model is an important issue in the FEM simulation of cutting in order to achieve a good accuracy, In this paper the milling operation will be considered. This is very common in manufacturing and, often, it represents the last operation, determining the final product quality. Cutting forces, measured by dynamometer table, and temperature, measured by infrared camera, have been recorded during milling tests. The infrared camera captures a part of the workpiece close to the cutting edge. First the material model has been set up considering only cutting forces; next, a sensitivity analysis about the material model parameters has been performed in order to assess the influence of temperature in the determination of the material parameters.
Deformation and Microstructure in Machining
Authors: Guo Yang , Saldana Christopher , Mann James B. , M'Saoubi Rachid , Chandrasekar Srinivasan
Published: April 2011

Deformation history and state of chip and machined surface in low-speed cutting have been characterized using image analysis, complemented by microstructure and hardness. Fine scale details of the deformation field of relevance to machining modelling are highlighted. The severe plastic deformation inherent to chip formation results in microstructure changes which can be controlled through appropriate process parameters selected with the aid of machining simulations. Scaling of subsurface strain distribution is observed. Similarity in deformation history of chip and near-surface suggests opportunities for engineering surfaces with controlled deformation levels and microstructures, directly, by machining. The deformation characterization offers substantial scope for improvement and validation of machining models, and enhancement of machining process capability.
Technological and Environmental Aspects in Milling of γ-TiAl
Authors: Priarone Paolo Claudio , Rizzuti Stefania , Rotella Giovanna , Settineri Luca
Published: April 2011

Gamma-titanium aluminides present an attractive combination of low density, high melting temperature, good oxidation and burn resistance, high modulus and strength retention at elevated temperatures, and good creep properties. For this reason they are promising candidates as advanced structural materials for high temperature applications. However due to their high strength, high hardness and brittleness at room temperature, g-TiAl alloys are regarded as difficult-to-cut materials. Many efforts have been done during the last 20 years to introduce TiAl-based alloys into the aerospace and automotive market as engineering components. But for the application and diffusion of this new heat-resistant light-weight material for high performance components, a deeper knowledge of their machinability is still required. In this context, and given the increasing attention to the environmental aspects related to the manufacturing processes, the present research work is aimed at investigating two key aspects: the influence of cutting parameters and cooling conditions, on tool wear, surface finishing and power consumption in milling operations of a g-TiAl alloy.
Evaluation of the Cutting Force and Geometric Error for Roughing Operation by Plunge Milling
Authors: Bonetti Ivandro , Oliveira Valter Vander , Souza Adriano Fagali
Published: April 2011

Nowadays there has been noticeable an expressive technological development in the cutting process to machine moulds and dies, through applying new materials, cutting tools and machining strategies. The rough operations depict an important portion in the machining time of these pieces. In front of this scenario, a new milling rough operation in the tool’s axial direction represents a possibility to optimize this machining process so as decreasing the machining time and increasing the material removes rates. A few scientific studies have been carrying out at this thematic, limited to a technical-commercial researches. Therefore this work contributes with the knowledge in this machining process through an experimental trial analyses. In special it studies the cut direction effects during climb and conventional milling in these operations. The result quantifies the cutting parameters influence at the cutting force and error form.
A Metal Cutting Approach to Investigate the Tribological Properties of Nano Crystalline Boric Acid and the Effect of its Carrying Medium
Authors: Ramana S.V. , Ramji K. , Satyanarayana B.
Published: April 2011

The pin on disc (POD) tests revealed an inverse relationship between coefficient of friction and the particle size of boric acid. So, as the properties of materials are changing with respect to its spatial dimension, the tribological performance of solid lubricant in the metal cutting is a matter of research. The present work aims at investigating the effect of variation of particle size of boric acid in the nano level in the machining of hardened steel. Canola oil and SAE 40 oil are tested as the carrying media for nano crystalline boric acid. In both cases, all the machining parameters viz. cutting forces, tool temperatures and surface roughness increased with the decrease of the particle size in nano level. The effect of carrying medium is also targeted and SAE 40 oil has been found as the best.
Simulation of Multiple Chip Formation when Broaching SAE 5120 Low Alloy Steel
Authors: Schulze Volker , Osterried Julius , Meier Harald , Zanger Frederik
Published: April 2011

The paper aims to predict component conditions after each subprocess of a manufacturing process chain. A continuous simulation has to be achieved, considering the inheritance of component states. To identify functional descriptions between component conditions as input and output quantities a broaching simulation is being developed. It includes multiple chip formation with multi-toothed broaching tools and machining history of a component as well. For this purpose component conditions are extracted from and transferred to a workpiece model as an initial condition. The 2D finite element chip formation model uses remeshing for material separation allowing highly detailed surface layer characterizations. Parallel experimental studies vary process parameters, whose objective is optimization of process control and forecast of component properties. Characterization of component conditions is based on distortion analysis, cutting force and surface measurements. Comparing the specific cutting forces between simulation model and performed experiments show a reasonable agreement of results
A Hybrid Approach to Predict Residual Stresses Induced by Ball-End Tool Finishing Milling of a Bainitic Steel
Authors: Guillemot Nicolas , Beaubier Benoît , Braham Tarek , Lartigue Claire , Billardon René
Published: April 2011

The objective of this study is to predict the residual stresses induced by ball-end milling using an hybrid approach based on a numerical simulation where thermo-mechanical loads equivalent to the cutting process are applied directly on to the final surface of the workpiece without modelling the material removal. The applied loading is derived from the measurement of the maximum cutting forces and the measurement by IR camera of the temperature in the tertiary shear zone. The 2D simplified model proposed herein is derived from the analysis of oblique cutting with elementary cutting tools and makes it possible to take account of the normal rake and local helix angles as well as the lead angle of the tool. The feasibility of the approach is assessed by comparing experimental measurements and numerical predictions of the residual stresses induced by ball-end tool finishing milling of flat specimens made of a bainitic steel.
3D Numerical Prediction of Residual Stresses in Turning of 15-5PH
Authors: Mondelin Alexandre , Valiorgue Frédéric , Rech Joël , Coret Michel , Feulvarch Eric
Published: April 2011

This study presents the development of a numerical model for the prediction of residual stresses induced in finish turning of a 15-5PH martensitic stainless steel. This methodology uses a hybrid approach combining experimental results (friction and orthogonal friction tests) with a numerical model. The numerical model simulates the residual stresses generation by applying cyclic equivalent thermo-mechanical loads onto the machined surface without modeling the chip removal process. The three-dimensional approach enables to study the influence of the turning passes interactions. It has been shown numerically that the periodicity of loading leads to a significant heterogeneity of material solicitations. Moreover, overlapping of passes accentuates these effects. So, the model highlights the necessity of a multi-passes simulation to reach a constant evolution of residual stresses along the feed direction. In addition, experimental measurements obtained by X-Ray diffraction have been compared with numerical results to validate the model.
Influence of Worn Tool on Polishability and Wear Resistance of VP20ISO Mold Steel
Authors: Zanatta André Marcon , Gomes Jefferson De Oliveira , Bressan José Divo , Barbosa Celso Antonio
Published: April 2011

The aim of this study was to evaluate the influence of tool flank wear on polishability and wear resistance of mold steel. Two surfaces of Villares VP20ISO steel were machined, one was roughed with worn tools (VB>0.3 mm) and another one with new tools (0.05 mm<VB<0.1 mm), followed by the finishing process of both surfaces by machining with new tools. The surface residual stresses were then measured using the X-ray diffraction method. Surfaces were etched down to different depths in order to monitor the residual stresses in the total affected depth of workpiece deformed layer. The results show that the cutting and passive forces provided the major differences between two machining conditions. The micro-hardness in the cross section did not show significant differences. Moreover, the residual stress measurements showed that after the finishing process, the surface roughed with new tools exhibited 100 MPa compressive stresses at 35 mm below the surface, while the surface roughed with worn tools provided a valley of tensile stress from the surface. Tests conducted on a pin-on-disk tribometer showed that the wear rates of the surface roughed with new tools were lower than the one roughed with worn tools and, after the polishing process, that the surface finishing of the surface roughed with new tools was better.
High-Speed Milling Characteristics and the Residual Stresses Control Methods Analysis of Thin-Walled Parts
Authors: Li Bei Zhi , Jiang Xiao Hui , Jing Huai Jing , Zuo Xiao Yan
Published: April 2011

With FEM software of AdvantEdge, a model was created to analyze cutting force and thermal in the high-speed milling process, this model included a complete milling process of cutter radius. Combined with experiments validation, in high-speed milling, the normal force is greater than the tangential force and result in greater residual stress of that direction, which indicates that mechanical force play an essential part on the formation of residual stress. When the speed is over certain scope, the cutting force decreases, but the cutting temperature has been rising. In Roughing, by limiting the range of high-speed the residual tensile stress impact can be reduced. While in finishing, as the feed rate reducing the residual tensile stress will decrease greatly, improving the surface quality of thin-walled parts.
Modulation-Assisted Machining: A New Paradigm in Material Removal Processes
Authors: Mann James B. , Guo Yang , Saldana Christopher , Yeung Ho , Compton W. Dale , Chandrasekar Srinivasan
Published: April 2011

Modulation Assisted Machining (MAM), based on controlled superimposition of low-frequency modulation to conventional machining, effects discrete chip formation and disrupts the severe contact condition at the tool-chip interface. The underlying theory of discrete chip formation and its implications are briefly described and illustrated. Benefits such as improved chip management and lubrication, reduction of tool wear, enhanced material removal, particulate manufacturing and surface texturing are highlighted using case studies. MAM represents a new paradigm for machining in that it deliberately employs ‘good vibrations’ to enhance machining performance and capability.
An XPS Study of the Stratified Built-up Layers Developed onto the Tool Surface in the Dry Drilling of Ti Alloys
Authors: Salguero Gómez Jorge , Batista Moises , Sanchez Galindez Jose Antonio , Marcos Mariano
Published: April 2011

Secondary tool adhesion wear is commonly provoked by two effects, whose nature depends on the placement of the adhered material. The so-called Built-Up Layer (BUL) is formed on the tool rake face and the Built-Up Edge (BUE) is developed on the cutting tool edge. These effects can be developed by different causes depending on both the cutting conditions and the material to be machined. In this work, X-Ray Photoelectron Spectroscopy (XPS) has been used to analyze the built-up layers formed during the dry drilling processes of aeronautical Ti-6Al-4V alloy. Changes in the Ti oxidation state in each layer have allowed proposing a BUL formation mechanism based on chemical reactions of the workpiece material during the drilling process. Effects of these reactions have been contrasted through the XPS analysis of the chip generated in the process. In parallel, SEM and EDS have been used as complementary techniques for obtaining further information about the BUL nature.
Experimental Design Applied to the Machining of Windows Cage Ball Joints Homokinetic SAE 8620 Steel with CBN Tool
Authors: Coppini Nivaldo Lemos , Santana José C. C. , Baptista Elesandro Antonio , da Rosa Daniel B. , Alcantara Aroldo
Published: April 2011

In this work a factorial planning had been used to evaluate the CBN tool life during cut-ting SAE 8620 steel. Part U2222 of a TPGW 160408 insert of TX-LS TB650 and 2NU-SHMA6942 S7182BN300 classes from two manufacturers were used in this experiment. A 23 factorial design was used In cutting process to evaluate the behavior of the tool life and reason of the exchange of the part on influences of the chamfer (in S and T+S), the advancing speeds (0.09, 0.10 and 0.11 mm/rpm) at a cutting speed of 91.2 m/min. Model have been fit by variance analysis (ANOVA) and the processing optimization was done by response surface methodology (RSM). Results showed that a hyperbolic model had more adjusting than other models and the optimization showed a high life time for the TX-LS TB650 tool from A manufacturer on 0.09 mm/rpm of advancing speed, where it was observed that the pre-cranking was the reason of the exchange.