bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational Fluid Dynamics (CFD) Based Simulated Study of Multi-Phase Fluid Flow
Authors: Malik M. Rizwan , Shi Tie Lin , Tang Zi Rong , Liu Shi Yuan
Published: December 2010

It is critical to understand multiphase flow applications with regard to dynamic behavior. In this paper, a systematic approach to the study of these applications is pursued, leading to separated flows comprising the effects of free surface flows and wetting. For the first time, wetting phenomena (three wetting regimes such as no wetting, 90ºwetting angle and absolute wetting) are added in the separated flow model. Special attention is paid to computational fluid dynamics (CFD) in order to envisage the relationship between complex metallurgical practices such as mass and momentum exchange, turbulence, heat, reaction kinetics and electromagnetic fields. Simulations are performed in order to develop sub-models for studying multiphase flow phenomena at larger scales. The outcomes show that a proper mixture of techniques is valuable for constructing larger-scale models based upon sub-models for recreating the hierarchical structure of a detailed CFD model applicable throughout the process.
Localised Vibrational Mode in CuO:Sn (5 at%) Nanoparticles
Authors: Mariammal R.N. , Ramachandran K.
Published: December 2010

An experimental and theoretical investigation of defect modes in tin-doped cupric oxide (Sn-doped CuO) nanoparticles synthesized via a one-step solid-state reaction was reported. The defect mode at 455 cm-1due to Sn doping in CuO nanoparticles, calculated using a molecular model, was compared with the experimental value of 458 cm-1obtained from the FTIR vibrational spectrum. The Debye-Waller factor (DWF) of CuO nanoparticles was determined using Rietveld refinement of the XRD pattern and the Wilson’s plot, and the results were discussed on the basis of the number of surface atoms and thermal vibrations. The effect of defect modes upon the DWF of Sn-doped CuO nanoparticles was also discussed.
Local Density Diffusivity (LDD-) Model for Boron Out-Diffusion of In Situ Boron-Doped Si0.75Ge0.25 Epitaxial Films Post Advanced Rapid Thermal Anneals with Carbon Co-Implant
Authors: Wirbeleit Frank
Published: December 2010

Boron in silicon has presented challenges for decades because of clustering and so-called transient enhanced diffusion [1-2]. An understanding of boron diffusion post rapid thermal annealing in general, and out of in situ doped epitaxially grown silicon-germanium films in particular, is essential to hetero junction engineering in microelectronic device technology today. In order to model boron diffusion, post-implantation, the local density diffusion (LDD) model has been applied in the past [3]. Via mathematical convolution of the diffusion model slope and the initial boron concentration profile, these former results were transferred to this work. In this way, non-diffusing boron was predicted to exist in the center of the presented in situ boron-doped films. In addition, boron diffusion control by co-implanted carbon was demonstrated and the applied LDD model was completed and confirmed by adapting A. Einstein’s proof [4] for this purpose.
Slow Positron Studies in Polymers
Authors: Shrivastava S.B. , Acharya Aman Deep , Sharma R.
Published: December 2010

The diffusion trapping model has been applied to slow positron annihilation in He+ irradiated polystyrene and polystyrene – polystyrene bilayers. The S-parameter and the positron lifetime have been calculated as a function of the incident positron energy. The effect of the fluence upon the nature of the S-parameter curve has been discussed. It has been found that a change in fluence affects positronium formation. The transition rate for surface to positronium formation has been found to be dependent upon the fluence and the atomic number of the irradiated ion. The lifetime results show that, at low energy, the o-Ps annihilates mainly at the polymeric surface. The free volume hole concentration is found to decrease at low energy, and becomes constant at higher energies.
Dynamics Characteristics of High Speed Ball-End Milling Cutter for Machining Hardened Steel
Authors: Jiang Bin , Zheng Min Li , Zhou Jun , Xia D.H.
Published: December 2010

In order to depress cutter vibration caused by high hardness and periodic change of cutting force in high speed milling complex surface, investigated the modal characteristics of ball-end milling cutter through the modal analysis and transient analysis. Using the models of dynamic cutting force and cutting vibration, acquired dynamics characteristics of high speed ball-end milling cutter by the spectrum analysis of dynamic cutting force, simulation analysis of cutting vibration and experiment of high speed milling hardened steel. Results indicate that high speed ball-end milling energy concentrates in few special frequencies, the rotational speed and the numbers of cutter teeth determine the fundamental frequency. High speed ball-end milling cutter easily makes radial bending vibration by the lower modal characteristics, the overhang and inclination angle of cutter affect its dynamics characteristics significantly, and the modal parameters and vibration model of cutter acquired by step response method have higher credibility.
Investigation of Laser Scribing Technics for Reducing Core Loss of Grain-Oriented Silicon Steels
Authors: Huang Y. , Liu Y. , Zhu G.L.
Published: December 2010

A laser is often considered to scribe the steel surfaces after cold-rolling and annealing to reduce the energy losses associated with hysteresis and eddy currents. In order to maximize the loss reduction of this process, the laser scribing technics was investigated in details. In this work, three laser scribing parameters including pulse energy, scanning velocity and scribing spacing, which are highly related to the loss reduction, were selected for the study. A L9(34) orthogonal experiment was designed and carried out by an Nd:Yag laser marking machine. The results indicate that the subsequence of significance of the three factors on core loss reduction is as follows: pulse energy, scribing spacing and scanning velocity. And an optimized combination of parameters is obtained by range method.
Research of Magnetic Induction Intensity on Magnetic Abrasive Finishing
Authors: Li Wen Hui , Chen Hong Ling , Yang Sheng Qiang , Yang Shi Chun
Published: December 2010

As a kind of precise surface finishing technology, magnetic abrasive finishing has wide application, low cost, high efficiency, good effects, and other advantages. Magnetic induction intensity is one main parameter affecting finishing effect and efficiency of magnetic abrasive finishing. Saturation magnetic induction intensity for different magnetic abrasives is defined through test device designed by ourselves. Affecting rules of saturation magnetic induction intensity is discussed by experiments, which provide basis for parameters selection and practical application of magnetic abrasive finishing.
Research on the Automatic Programming System for Industrial Robots in Free-Form Surfaces Polishing
Authors: Zhan Jian Ming , Liu Q.T. , Wang Gang Ming
Published: December 2010

Because of the industrial robot’s advantages and characteristics of degree of freedom, it is broadly applied in mold and die of curved surfaces polishing. But its excessive degree of freedom also brings great difficulties in programming for there is CAD/CAM software can do it well. By analyzing the ISO NC code and robot’s programming criterion, this paper develops off-line programming software for industrial robots in free-form surfaces polishing.
FEM Investigation of Machinability Properties of SiCp/Al Composites
Authors: Zhou Li , Huang Shu Tao
Published: December 2010

In this paper, a transient dynamic finite-element analysis was carried out to investigate the effects of the cutting speed on cutting force, cutting temperature, and the chip-shear angle. The workpiece material is SiCp/Al composites with lager particle and high volume fraction. The results show that the cutting force decreased, while the cutting temperature and chip-shear angle increased evidently with increasing of cutting speed. The results obtained from this study can predict the behaviors of machining SiCp/Al composites very well and the variation trend is agree well with that of the experiments.
Evaluation of Tool Wear when Milling SiCp/Al Composites
Authors: Huang Shu Tao , Zhou Li
Published: December 2010

The research on wear mechanism and characteristics of tool is a key issue for machining silicon carbide particle reinforced aluminum matrix composites (SiCp/Al). The machining adaptability, wear characteristics of the cermet cutting tools, TiN-coated tools and cemented carbide tools have been studied while milling SiCp/Al composites with large particle and high volume fraction. The results indicate that the wear resistance of the three kinds of tools are almost the same during machining large particle, high volume fraction SiCp/Al composite, and the tool wear is mainly presented as flank wear, which is caused by the mechanical wear of SiC particles. The wear rate of tools increases with increasing the cutting speed, but the difference is not very obvious. However, no matter high-speed cutting or low-speed cutting, the tool will be seriously worn in short distance. The each tooth cutter feed rate and depth of cutting have little effect on the tool wear.
Experimental Study of Micro-Electrode Array by Micro-WEDM
Authors: Geng X.S. , Wang Yu Kui , Wang Zhen Long , Shan De Bin
Published: December 2010

This paper discusses a processing preparation for micro-electrode array fabrication by micro wire electrical discharge machining. Based on a self-developed micro-WEDM machine tool and adopted thin tungsten wire electrode of 30μm in diameter, a series of experiments on micro-electrode array machining are introduced. The relationship between the discharge gap and working area of wire discharge under given voltage is investigated. The examination for micro-girder structure forming process has gone along and the axle journal's minimized width of least micro girder which could not bring on machining flexural thermal deformation has been obtained. The clamping method of work-piece intended for electrode array fabrication is analyzed and a special fixture is designed. The factors affecting forming accuracy are summarized. An amounted 5×5 squared-disk-type micro-electrode array structure with a high aspect ration, namely 20μm in axle journal width and 500μm in length of a single electrode, has been machined successfully.
Research and Correction on Cone Angle Effect of CBCT
Authors: Zhang Feng Shou , Deng Xiao Zhong , Cui F.K.
Published: December 2010

The cone angle effect of CBCT system and affecting reconstructing slice are discussed. The CC-FDK algorithm is introduced. The redundancy data is not disposed accurately in FDK algorithm. The thesis puts forward a weighting projection method based on cone angle and distance to center plane. The method compensates the information of projection unused in FDK algorithm. The simulation model is scanned and reconstructed. The result indicates that this method can extend the cone angle of scanning.
Experimental Study on Deep Hole Drilling Gamma Titanium Aluminide
Authors: Zhu Lin , Chen Xin , Viehweger Bernd
Published: December 2010

γ-titanium aluminide is a new intermetallic structural material. γ-titanium aluminide alloy has the advantages of high temperature resistance, high performance of anti-oxidation effect, low-density, high specific strength and rigidity etc. But high strength, hardness and brittleness of the material also make processing difficultly. High cutting force and cutting temperature affecting a decline in cutting lifetime and cutting efficiency. This problem is more acute in deep hole drilling. In this paper, we have analyzed the cutting performance of γ-titanium aluminide and designed a deep-hole drills with appropriate tool material and geometric parameters. The experimental result shows: this drill bit is stable and efficient in drilling and can achieve a good quality.
Drilling Characteristics of SiC Particle Reinforced Aluminum-Matrix Composites with Ultrasonic Vibration
Authors: Xu Xing Xin , Zhang Xiao Hui , Liu Chuan Shao , Zhao Bo
Published: December 2010

With the rapid development of aviation at home, particle reinforced metal matrix composites (PRMMCs) has been widely applied recently. But at the same time, the difficult machining has gradually been one of the most outstanding bottle-necks that restrict the rapid enhancement of productivity. Here, in virtue of the self-developed ultrasonic drilling equipment, hole-making experiments of common and ultrasonic vibration drilling are performed on SiC particle reinforced aluminum-matrix composites （SiCp/Al）with different content of SiC by using two types of tungsten carbide drill. Drilling characteristics of machining composites with ultrasonic vibration are analyzed from such respects as the composites crush, drilling force, drill wear and hole surface quality. Studies show that, during the ultrasonic vibration drilling process, SiC particle in the composites is prone to break along the crystal connection boundary or suffer ductile fracture under the dynamic ultrasonic impulse, in which the cutting resistance could be reduced and the tool edge could be protected. Thereby, drilling locating precision and hole surface quality could be enhanced, wear of the drill chisel edge effectively improved, and the drilling torque reduced about 30%.
Research on Image Detection Platform of Embryo Vaccine
Authors: Xie Tan Cheng , Zhai J.J. , Nan X. , Hu Z.Y.
Published: December 2010

The current deficiencies in domestic vaccine embryo is mainly dependent on artificial visual identification to identify, This has resulted in the detection speed and accuracy is not high, This has resulted in the detection speed and accuracy is not high, poor security features. In order to change the traditional manual operation mode, this article put forward the concept of image detection platform. Hardware aspect through CCD camera gain image, Takes the imagery processing by the core of TMS320DM642, the software aspect introduces operating system's programming thought to the imagery processing each function modulation, the system imagery processing uses VC++ to confirm the examination algorithm in advance, to reduce the development cycle. The experimental result indicated that this system changed the traditional manual control pattern, raised the examination speed and the rate of accuracy.
Temperature Field Simulation of Anode Erosion in Electric Discharge Machining
Authors: Xie B.C. , Wang Zhen Long , Wang Yu Kui , Cui Jing Zhi
Published: December 2010

In this paper, a thermo-physical model of the electric discharge machining process using finite element method is presented. In this model, parameters such as convection, the latent heat and the thermal properties based on temperature dependent etc. are studied to predict the temperature distribution in the workpiece. The temperature field simulation and experiment were carried out by adopting parameters through optimum pulse curve, and amending the effects of recast layer, the simulation results amended shows a better agreement with experimental results, indicating a theoretical foundation for mechanism of material removal in EDM machining.
Parametric Design of Tractor Configuration Using API Based on CATIA
Authors: Li Ji Shun , Chen L.H. , Li L.
Published: December 2010

The traditional shape design method of tractor is mainly completed based on the manual design. Messages are transmited mainly through material object, model, blueprint and template. The material object and model even have a small change that will cause massive chain-reactions such as tedious blueprint revision. And there will be a great many of problem, such as the development cycle of tractor to be long, the accumulative error of design to be big, the development cost to be high and product universalization and serialized degree to be low. This problem is key problem to be solved for shape designer. Advanced design method such as CAD/CAM provid solutions for us, and especially the concept of parametric design was applied. In this paper an appfoach for the parametric design of tractor configuration will be presented. To this end, there are two key issues to be solved: First, the parametric representation of the tractor configuration, second，how to generate a three—dimesional shape of the tractor automatically based on the parametric representation. The parametric design of the tractor configuration is implemented by making use of the API technique of the CAD software，namely automation in CATIA．The test example shows that the approach presented is able to generate a three dimensional shape of the tractor automatically and meet the need of the parametric design of tractor configuration.
Research on Establishing Assessment Datum Plane of Three Dimensional Surface Micro-Topography
Authors: Cui Feng Kui , Li Y.X. , Wang X.Q.
Published: December 2010

For making accurate assessment about each characteristics paramete of three-dimensional surface micro-topography, mathematic model for the datum plane of three-dimensional surface micro-topography assessment was established with least squares method, the relational expression of the average fitting error and maximum error were made. The datum plane equation was found by processing experimental data with least squares fitting method. The rationality and feasibility of the algorithm which is used to establish datum plane were verified through error calculation and analysis of the datum plane equation. The research provides the foundation for parametric assessment of 3D surface micro-topography and provides a method for datum surface establishment of curved surface.
Simulation and Experiment on the Vibration Performance of Pre-Loaded Multi-Plies Bellows
Authors: Ma Wei , Yu Yong Jian , Liu Yong Gang , Li Ji Shun , Xue Yu Jun
Published: December 2010

As major equipment for damping and sound insulation, bellows are used as flexible joint and elastic element in the pipeline system of naval ships. In this paper, Finite Element Method was adopted to analyze the static and dynamic performance of bellows. Fourply bellows model was built, which 0~1.2MPa pressure is loaded. Then the stress, vibrating type and frequency of bellows were gotten. The result of simulation shows that the frequency of bellows increases linearly with the increase of pre-loaded. New equipment was produced to test the vibration performance of bellows. The vibration performance of fourply bellows was researched. The frequency, stiffness and damping of bellows were gotten. Some rules were summarized. The result of experiment shows that the frequency and stiffness of bellows increase with the increase of hydraulic pressure. In addition, while the hydraulic pressure is less than 0.8MPa, the damping of bellows increases with the increase of hydraulic pressure. While the hydraulic pressure is more than 0.8MPa, the damping decreases with the increase of hydraulic pressure.
A Study on Chip Breakage in Mini-Pore Vibration Drilling for Hard-to-Cut Material of Austenitic Stainless Steel
Authors: Zhou J.S. , Ye Bang Yan , Lai Xing Yu
Published: December 2010

This research aims to improve the method of Mini-pore Drilling superimposed an axis vibration for hard-to-cut material of Austenitic Stainless Steel 1Cr18Ni9Ti, as well as to make it easier for the chips to be discharged. A mathematical model of vibration drilling is presented, and the relationship between the vibration parameters and cutting parameters to generate little and short broken-chips in vibration drilling is investigated, analyzed and verified by experiments. The results show that when the processing parameters meet the conditions given in this article, stable and reliable chip-breaking can be achieved. The results provide a theoretical guidance to achieve chip-breaking in mini-pore vibration drilling for hard-to-cut material.
Research on Grinding Technology of Isometric Polygonal Profile
Authors: Wang De Sheng , Zhou Ai Ping , Tong Jing Lin
Published: December 2010

On the basis of analyzing the structure characteristics of the Isometric Polygonal Profile (IPP) hole, equations of the track for grinding wheel center and the formula of calculating node coordinates according to equal-error linear approximation method are established and the determination method of grinding technology parameters value and problems to be attention at grinding process are discussed. Grinding experiments show that both processing precision and surface roughness can reach with the fit requirements of IPP connection according to these principles. It is available for reference that grinding complex non-circular column surface is ground by CNC machine tools.
Research on the Unstability Motion of BTA Deep Hole Boring Bar
Authors: Zhao Wu , Huang Dan , Hu Zhan Qi
Published: December 2010

Analysis of BTA deep hole drilling bar on Liquid-Solid Coupled Vibration model, there are vortex and unstability on bending deformation of the rotating boring drilling bar induced by cutting fluid force. At first, the rotating fluid force inside the boring bar was expressed linear physical form, and it’s stiffness and damping coefficients were derived by the unsteady reynolds dynamic equation of the fluid. Then establish conditions including eddy and mechanical mechanism of the boring bar by cutting fluid force. The results of analysis show that the solution on coupled vibration model are more accurate than the other vibration model. Coriolis effect is the main reason for eddy or unstability of the deep hole boring bar induced by cutting fluid internal the drilling bar’s wall. Some rules are also derived with which cutting parameters can be selected reasonably, which is coincide with the parameters used in heavy machine building industry.
Influence of Original Structure on the Grind-Hardened Layer Structure and its Property of 65Mn Steel
Authors: Liu Lian Fen , Zhuang Jie Zhen , Huang S.W. , Xu Zhi Long
Published: December 2010

On the basis of the surface grind-hardening experiment, the influence of original structure on the grind-hardened layer structure and its property of 65Mn steel were studied using optical microscope, scanning electron microscope, and digital microhardness tester in detail. The results show that under the comprehensive function of the temperature field and the stress-strain field, original structures have little remarkable effect upon the microstructure of grind-hardened layer and its high microhardness value. The hardened layer comprises entirely hardened zone and transitional zone, and the entirely hardened zone whose microhardness ranges from 810HV0.5 to 870HV0.5. Additionally the depth of grind-hardened layer and entirely hardened zone vary with different original structures, and the higher depth of it can be obtained when material initially quenched and tempered is selected.
Application of a Bayesian Network to Thermal Error Modeling and Analysis for Machine Tool
Authors: Li X. , Lei Q. , Li Z.H.
Published: December 2010

CNC machine tool dynamic thermal error compensation has always been a hot issue to improving precision. This dissertation proposes a method of machine tool thermal error modeling during processing, based on Bayesian network theory, by describing the correlation between the various factors of generated the heat error, through the sample data, analyzed and simplified the intrinsic correlation between these various factors, established the basic thermal error compensation model, and used the network’s good characteristic of self-studying, combining the result of update collection data, continually modify the model to reflect the machining process condition changes. Finally, the experimental results show the feasibility of Bayesian network model, it was a stronger application for achieving the thermal error compensation.
Study on Model of Ultrasonic Polishing Machining - Pulse Electro- Chemical Machining Compound Finishing for the Hard and Brittle Metals
Authors: Zhang Cheng Guang , Hu Y.Z. , Zhao Bo
Published: December 2010

The application of ultrasonic polishing and machining pulse electrochemical machining compound finishing is presented in the paper. The machining principle and experimental set-up of UPM-PECM compound finishing are introduced in the paper, discussing mechanism and model of the UPM-PECM in theory, and carrying on the experiment, which would co-act on hard-brittle metals in the machining. Furthermore, the material removal depth of UPM-PECM compound finishing is approximately proportional to the polishing time, and would decrease with the polishing time. This study indicates that machining velocity, machining accuracy and surface quality can be improved under UPM-PECM.
Quality Control and Tracing System of Automotive Airbag Flexible Assembly Line
Authors: Shi X.J. , Li Fang Tao , Zhang Y. , Gao Z.D.
Published: December 2010

As an important component of automobile, the quality control and tracility of airbag’s manufacturing process is very important. In this situation, an assembly line is put forward which is made up of computer, barcode scanner, electric nut runner and specialized electric testing instrument. System uses the Client/Server framework , bar code technology and SQL database to save or find the assembly data and the information of the operators. Electric nut runner is used to control the torque value of the nuts. Specialized electric testing instrument is used to test the electric parameters of the airbag. By the practical application in the assembly line, there are many advantages of this system such as good human-machine interface, fast response, and so on. This system can be used for many products, and it is an flexible assemble line with procedures rectification, quality control and product tracing.
Ontology-Based Knowledge Modeling for Collaborative Product Development
Authors: Lv Kun , Zeng Qing Liang , Li Yan Feng
Published: December 2010

The process of Collaborative Product Development (CPD) comprises highly creative and knowledge-intensive tasks that involve extensive information exchange and communication among distributed teams. Traditional information management systems fail to provide adequate capability to support CPD, due to their inflexible data structures and hard-wired usage procedures, as well as their restricted ability to integrate process and product information. An ontology-based method of knowledge management is proposed to support CPD. The key idea hiding in the method is a flexible ontology-based schema with formally defined semantics that enables the capture and reuse of design knowledge. A part of CPD-oriented ontology library represented by UML is displayed.
Theoretical and Experimental Study on the Structure and Vibration Isolation Characteristics of a Hydraulic Engine Mount
Authors: Li Qian , Zhao Bo , Zhao Jian Cai
Published: December 2010

Hydraulic engine mounts (HEMs) are important vibration isolation parts in vehicle powertrain mounting systems, and the structural parameters of HEMs are the main factors which determine their vibration isolation characteristics. It is of great significance to discover the influences of the structure parameters on their vibration isolation characteristics in the design and study of HEMs. Firstly, the vibration isolation characteristics of HEMs are analyzed theoretically using a simplified lumped parameter (LP) model. Secondly, the HEMs with different rubber materials, lengths and cross-sectional areas of the inertia tracks are designed and manufactured, and their frequency response characteristics are investigated by experimental and analytical methods. Finally, the influences of these structural parameters on the vibration isolation characteristics of HEMs are educed. The analytical methods and conclusions are instructive for the design and tuning of the vibration isolation characteristics of HEMs.
Synchronous Control Research Based on Hybrid Network
Authors: Lu F.P. , Wu J.Z. , Liu Jun Li
Published: December 2010

This paper is concerned with a synchronous control problem of distributed systems with wired and wireless hybrid communication network. A discrete tracking error mathematical model is established based on prediction model and non-memory state feedback controller. A sufficient condition for asymptotic stability of state tracking error between the master system and slave system is presented by constructing Lyapunov function, and a linear matrix inequality (LMI) approach has been employed to obtain the tracking controller gain matrix.
Experimental Research on the System Performance in Near-Dry Deep Hole Drilling
Authors: Zhao H.B. , Nan Y.F.
Published: December 2010

The near-dry deep hole drilling system was taken as object in this study，and the contrast experiment between the deep hole drilling system and the traditional（wet）deep-hole drilling system，including the cutting force，the tool wear，the surface quality and the chip-break have been done. The results show that the near-dry system drill stability and have better effort in cooling，lubrication，chip removal effective. The tool life and surface quality within the hole are better，at the same time，it can greatly reducing the amount of cutting fluid，the costs and the pollution of the environment. So we can get a conclusion that it is an ideal system in green drilling process.
Updating the Finite Element Model of a Bridge Model Using a Hybrid Optimization Method
Authors: Hao Xiang Wei , Liu Yang
Published: December 2010

Finite element model updating of structures usually ends up with a nonlinear optimization problem. An efficient optimization technique is proposed firstly, which draws together the global searching capability of chaos-based optimization technique and high searching efficiency of trust-region Newton method. This hybrid approach is demonstrated to be more efficient and prone to global minimum than conventional gradient search methods and random search methods by testifying with three test functions. The optimization problem for model updating using modal frequencies and modal shapes is formulated, and a procedure to update the boundary support parameters is presented. A modal test was conducted on a beam structure, and the identified mode frequencies are employed to formulate the optimization problem with the support parameters as the updating parameters. The discrepancy between the mode frequencies of the finite element models before and after updating is greatly reduced, and the updated support condition meet quite well with the insight to the devices that form the supports.
An Improved Taguchi Method and its Application in Finite Element Model Updating of Bridges
Authors: Sun Hang , Liu Yang
Published: December 2010

In the model updating process, the objective function is usually set as the weighted sum of the difference between analytical and experimental dynamic characteristics. But it is difficult to select the weighting factors since the relative importance of each parameter to updated results is not obvious but specific for different problem. To overcome this problem, multi-objective genetic algorithm (GA) is introduced into model updating by Gyeong-Ho Kim since there is no need for selecting weighting values in multi-objective optimization technique. To complex structures, however, it is difficult to update the structural models by GA because of the relative low efficiency. While Taguchi updating method, deemed as an efficient and robust method, is a good choice to update the models of large structures. But Taguchi method is only applied to solve the single objective optimization problem of model updating. Therefore, this paper proposed improved Taguchi updating method to deal with the problem of model updating using multi-objective optimization technique. Then the proposed method is applied to update the model of a 14-bay beam with measured frequencies and modal shapes. The updated results show that the proposed method is promising to structural model updating.
Nonlinear Seismic Response Analysis of Half through CFST Arch Bridge under 3-D Earthquake Waves
Authors: Ma Jun , Chen Yan Jiang , Liu Li Peng
Published: December 2010

A finite-element model for CFST members using a 3D composite beam fiber element is presented which accounts for the nonlinear constitutive models of steel and concrete separately. The model is proved to be valid by comparing the computational results of some test specimens with their experimental data. Using this model, a CFST arch bridge’s seismic response was calculated. The result indicated that the magnitude of displacements and moments at arch crown increases up to 10 percent caused by CFST hysteretic behavior which should be seriously considered during seismic design. Some measures and suggestions bring forward to guide the design and construction of this type of bridge.
The Effect of Nitrogen and Inoculation on the Tensile Properties and Microstructure of Cast Iron with Lamellar Graphite
Authors: Wilberfors Fredrik , Svensson Ingvar L.
Published: December 2010

The main purpose with this paper is to show the effect of nitrogen and inoculation on the tensile properties and microstructure of cast iron with lamellar graphite. Casting experiments were performed with the main composition: 3.4 % C, 2.0 % Si, 0.7 % Mn, 0.5 % Cu. The nitrogen content was varied between 90-180 ppm and inoculant was added as 0, 0.2 or 0.4 % by weight.
The addition of inoculant changed the graphite structure from distribution D/B/A to distribution A, according to ISO 945. The eutectic cell size decreased significantly. The addition of inoculant had no influence on the hardness. The addition of nitrogen shortened the graphite flakes and increased the hardness. The influence on the eutectic cell size was low and there was no significant effect on the graphite distribution.
Tensile test samples were analysed by true stress – true plastic strain in terms of the flow relationships proposed by Hollomon, , and Ludwigson, . The stress-strain curves were fitted to polynomial functions of the 6:th to 8:th order before evaluating the constants in order to eliminate noise from the measurements. This approach also enabled the slope of the stress-strain curve to be evaluated at zero stress (Young’s modulus), resulting in plastic strain from stress levels close to zero.
The Hollomon flow relationship failed to describe the deformation behaviour for the whole range of the stress-strain curve. The correction terms in the Ludwigson flow relationship resulted in a better fit. The addition of inoculant mainly affected the strength coefficient, . The addition of nitrogen also affected the constant. The main reason for this was that the addition of inoculant influenced the last part of the stress-strain curve while the addition of nitrogen had an effect over the whole range of the curve. The addition of nitrogen and inoculant increased the tensile strength from 288 MPa to 393 MPa and the total elongation at fracture from 0.8 % to 1.6 %.
Development of Hypereutectoid Steel with Nodular Graphite
Authors: Kozak Dmytry S.
Published: December 2010

This work studies the formation of cast structures in hypereutectoid steel modified by alloying modifiers (Fe30Si55Mg7Ca2REM4, Fe34Si55Mg9Ca2 and Fe63Ni30Mg7) together with inoculants Fe20Si60Ba20. It is found that at spheroidizing by 0.7 % Fe63Ni30Mg7 and inoculation by 1.5 % Fe20Si60Ba20 causes the formation of inclusions of nodular graphite with nodularity exceeding 90 % and a structurally-free cementite structure is obtained. The mechanical properties of the steel with nodular graphite modified by Fe63Ni30Mg7 and Fe20Si60Ba20 are as follows: tensile strength (σb) 660-680 МPа, yield strength (σ0.2) 520-540 МPа, percent elongation (δ) 5-8 %, impact strength (КС) 15-35 J/cm2, Brinell hardness (НВ) 241-255. After ferritic annealing these parameters were found to be σb =530-560 МPа, σ0.2=400-430 МPа, δ =20-24 %, КС=160- 180 J/cm2, 150-162 НВ.
Pearlite Stabilisation by Copper on Ductile Cast Iron
Authors: Tsujikawa Masato , Matsumoto Norikazu , Nakamoto Koji , Michiura Yoshisada
Published: December 2010

In ductile cast irons with copper, cementite stability was investigated against an annealing heat treatment used to obtain a fully ferritic matrix. Copper controls cast-iron mechanical properties, but its role in the matrix microstructure formation remains unclear. Some reports suggest the copper layer around graphite or cementite. They can be barrier to carbon diffusion at eutectoid reaction, however it is difficult to understand the mechanism of pearlite stability by copper. To confirm the existence of the barrier and effect of copper addtion, ten 9-mm-thick spheroidal graphite cast iron castings were prepared with different copper contents of 0.16 wt% – 0.69 wt%. The samples’ as-cast microstructures included spheroidal graphite, ledeburite, and pearlite. The pearlite fraction degreases to about 10% by heat treatment for ordinary ductile irons without intentional copper addition. The samples’ copper content and the pearlite fraction after heat treatment are not linearly related. The retained pearlite increased suddenly with increased copper content greater than 0.4 wt%. However, even the sample with the highest copper content showed no precipitation of a copper solid solution around graphite nodule or cementite.
Influence of Cooling Rate and Alloying Elements on Kinetics of Eutectoid Transformation in Spheroidal Graphite Cast Iron
Authors: Mrvar Primož , Petrič Mitja , Medved Jožef
Published: December 2010

Paper deals with influence of cooling rate and alloying elements on kinetics of eutectoid transformation in spheroidal graphite cast iron (SGI). Transformation of austenite can proceed into ferrite and graphite (FeFeG) and/or in pearlite (Fe  FeFe3C). Examination of eutectoid transformation was made by evaluating the “in-situ” dilatation curves together with metallographic examinations, DTA, and dilatation analyses in solid state. ThermoCalc software was applied for thermodynamic calculations of phase equilibria. Based on numerous quantitative relations, such as relation between fractions of ferrite and pearlite in the as-cast SGI that was determined by analysis of dilatometric curves and taking into account also composition of melt, ferrite/pearlite ratio in the microstructure could be determined in a very short time. Thus the melt composition could be corrected by adding Cu and/or Mn or Si, respectively, using the "in situ" dilatation analyses. Characteristic temperatures of eutectoid transformation have been established from the kinetics of austenite transformation and from temperature dependence of ferrite and/or pearlite growth. Kinetics curves that enable to determine fractions of single microstructure constituents in the microstructure as function of transformation time, mainly used for ferrite and pearlite SGI, can be well determined with physical sigmoidal Boltzmann model.
Notch Fatigue and Fracture Mechanics of Austempered Ductile Irons
Authors: Atzori Bruno , Bonollo Franco , Meneghetti Giovanni
Published: December 2010

In this paper the fatigue characterization of an austempered ductile iron (ADI) is presented. The aim of the work is to provide design engineers involved in fatigue assessments with an engineering tool suitable to deal with notches of different severity. Classically, U-notches are divided into blunt notches and sharp notches. The former are characterized by large notch tip radii such that the high cycle fatigue strength is controlled by the elastic peak stress, i.e. by the elastic stress concentration factor. The latter are characterized by reduced notch tip radii such that the effective stress which controls the high cycle fatigue strength is significantly lower than the elastic peak stress and their behaviour become similar to that of a crack having the same length. Blunt notches are assessed according to the classical Notch Mechanics principles, while sharp notches are treated with the Linear Elastic Fracture Mechanics approach. After presenting the classical Frost diagram which highlights the different fatigue behaviour of sharp and blunt notches, fatigue test results generated from notches of different severity are presented as well as a synthesis in a diagram able to account for short cracks/notches, long cracks, sharp notches and blunt notches.
Structural Refinement of 15%Cr-2%Mo White Irons
Authors: Nofal Adel , Reda Reham , Ibrahim Khaled M. , Hussein Abdel-Hamid
Published: December 2010

This research aims at studying the structural refinement of 15%Cr-2%Mo hypo- and hypereutectic white irons through dynamic solidification and Nb-alloying (1-2%Nb). Solidification behavior was studied using DSC. Microstructure investigation and analysis were performed using optical, image analyzer as well as SEM, EDX and XRD analysis. Refinement mechanisms proposed involved both enhancing nucleation and altering the growth process of the primary and eutectic phases either by fragmentation of the primary growing phase in the case of dynamic solidification or by consuming the available carbon from the liquid and hence the amount and size of M7C3 will decrease in the case of addition of Nb-alloying. Nb has higher affinity to carbon during solidification, higher formation temperature than the main microstructure constituents and forms fine carbide so Nb achieves refinement of the microstructure.
High Temperature Erosion Behaviors of High V-Cr-Ni Spheroidal Carbides Cast Iron
Authors: Shimizu Kazumichi , Naruse Takeshi , Xinba Yaer , Teramachi Hideki , Araya Shinji , Ishida Masahide
Published: December 2010

High temperature erosion occurs in production of the inorganic fibrous insulator in plant. Austenitic and martensitic stainless steels are often used for these severe high temperature erosion conditions. The paper presents erosion properties of some stainless steels, several cast iron and cast steel using a blast type high temperature erosion furnace. The solid particle erosion behavior at high temperatures (900°C) of carbon steel of S50C, carbon tool steel of SK3, SUS403, SUS630, and High V-Cr-Ni spheroidal carbides cast iron (SCI-VCrNi) are investigated. Alumina balls entrained in a stream of hot air impact on the target materials at an air velocity of 100 m/s. the impingement angle is 90°. The influence of the test temperature and the material removal are discussed. The high temperature erosion behaviors of specimens are discussed by the eroded surface morphology and vertical section observation using SEM and optical microscopy observations.
New Wear-Resistant Metastable Strain Hardenable Alloyed Cast Irons
Authors: Cheiliakh Oleksandr P. , Kolodyazhna Irina V.
Published: December 2010

This work addresses an urgent problem which is saving alloying elements (Ni, Mo, Nb, V, W and others) -which very scarce in Ukraine and other countries- while increasing the physical, mechanical and operational properties of the new designed and developed wear-resistant cast irons.
Optical microscopy, x-ray structure analysis, transmission and scanning (fracture) electron microscopy methods, different-thermal, magnetometric and x-ray analyses, as well as hardness and micro-hardness tests, impact energy, and abrasive wear tests in environments of cast-iron shots were employed in the research.
The work summarizes the controlling conditions for forming various metastable phases by including deformation (or strain) induced phase transformation (DIPT) and through realization in the process of testing. New wear-resistant economical alloyed cast irons with a metastable austenite-carbide and austenite-martensite-carbide structure are developed, which are being strain- hardened under impact-abrasive wearing operation conditions due to the realization of process DIPT in the superficial layer. These new cast irons are intended for manufacturing parts of different equipment (protective plates of sinter machines, furnaces, tracks for transferring raw materials at iron and steel works, etc.).
These cast irons do not contain expensive and deficit alloying components, like nickel, molybdenum, vanadium, and more expensive similar materials. Simultaneously they possess enhanced impact-abrasive wear resistance.
The Role of Alloy Design in Semi-Solid Casting of Ductile Iron Processed by Inclined Cooling Plate
Authors: Heidarian Bashir , Nili-Ahmadabadi Mahmoud , Moradi Marzyeh
Published: December 2010

The inclined Cooling Plate process can be considered as a reliable method for the production of semi-solid ductile cast iron. By utilizing aforesaid method, the main limitation of common semi-solid methods, i.e. Mg fading, will be eliminated. The present research is intended that the importance of alloying design through the inclined cooling plate method and its profound effect on obtaining the optimum solidification range for thixo-forming process have been illustrated. The optimization of solidification range for thixo-forming process has been gained by the simulation in both equilibrium and non-equilibrium conditions. Afterwards the alloy selection has been performed amongst several alloying composition with a view to their effect on the thixo-forming process and austempering.
Graphite Morphology Evolution during Melt Holding of Ductile Iron
Authors: Diao Xiao Gang , Ning Zhi Liang , Cao Fu Yang , Ren Shan Zhi , Sun Jian Fei
Published: December 2010

Evolution processes of graphite morphology in ductile iron were investigated by quenching specimens during a long time holding of iron melt in a Ar atmosphere. Results show that spheroidal graphite is only observed at the early stage of melt holding. There are no evident changes in morphology of spheroidal graphite with increasing holding time up to 180 min. Subsequently chunky graphite precipitates directly after holding for 240 min as spheroidizing ability (Mg residual and RE residual) is insufficient. The number and size of eutectic chunky graphite cells increase with prolonged holding time. It should be noted that vermicular graphite forms around eutectic chunky graphite cells after holding for 360 min. When holding time reaches 420 min, graphite morphology is flake-like together with some chunky graphite. The graphite morphology in ductile iron changes from spherical to chunky, then chunky to vermicular, finally to flake with an increase in melt holding time. Both spheroidizing ability and numbers of effective nucleus decrease with prolonged holding time of melt, which affect graphite morphology.
Modeling of the Divorced Eutectic Solidification of Spheroidal Graphite Cast Iron
Authors: Zhao Hong Lee , Zhu Ming Fang , Ştefănescu Doru Michael
Published: December 2010

The solidification of the austenite-spheroidal graphite (SG) eutectic is one of the most complex and therefore most difficult liquid-to-solid transformations to describe through computational modeling. This is because the iron-carbon equilibrium phase diagram is an asymmetric diagram that predicts that at relatively low solidification velocities it is possible to produce primary austenite in a casting of eutectic composition. In addition, the two phases of the eutectic solidify as a divorced eutectic, with only the austenite being in contact with the eutectic liquid. The paper proposes a computational model for the eutectic solidification of SG iron with visualization of the microstructure evolution using a cellular automaton technique. The model is an extension of the earlier Zhu-Stefanescu model for primary phase solidification and includes the growth of primary SG in the liquid, of primary austenite and of the austenite-graphite eutectic controlled by carbon diffusion through the solid austenite shell. The model outputs realistic images of the microstructure evolution from the beginning to the end of eutectic solidification of SG cast iron.