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    30 June 2011, Volume 16 Issue 3 Previous Issue    Next Issue

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    Properties and electronic structure of iron under pressure up to 30GPa
    Wu Y.-Q.; Yan M.-F.
    2011, 16 (3):  257-261.  doi: 10.1007/s12204-011-1139-y
    Abstract ( 10 )   PDF (715KB) ( 24 )  
    The properties and electronic structure of Fe under pressures of 0-30GPa have been studied by first principles employing the density functional theory (DFT), the ultra-soft pseudo-potentials (USPP) and the generalized gradient approximation (GGA). The calculating results show that there is a structural transition from magnetic body-centered cubic (bcc) to nonmagnetic hexagonal-close-packed (hcp) structure for Fe around 11GPa pressure. There is a pseudogap both in the density of states (DOS) for bcc and hcp Fe. The pseudogap of bcc Fe is deeper and wider than that of hcp Fe. The elastic modulus is obtained by Voigt-Reuss-Hill averaging scheme. The results indicate that the elastic properties of bcc Fe enhance with pressure except for elastic stiffness constant C11, shear modulus G and elastic modulus E at the transition pressure, while the elastic properties of hcp Fe increase linearly with pressure. Magnetic bcc Fe is ductile, and hcp Fe becomes ductile from brittle around 25GPa. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Numerical simulation of defect inspection using electromagnetically stimulated thermography
    Liu G.-F.; Li G.-H.
    2011, 16 (3):  262-265.  doi: 10.1007/s12204-011-1140-5
    Abstract ( 6 )   PDF (540KB) ( 24 )  
    The feasibility of electromagnetically stimulated thermography non-destructive testing (NDT) for the detection of defects in metallic conductive materials has been carried out by finite element analysis. Aluminum plates with defects of different diameters, depths, locations, shapes and orientation with respect to eddy current are numerically investigated. ANSYS software is used to solve the coupled electromagnetic and temperature field equations. The peak temperatures on the top surface of circular defects with different diameters and depths are calculated at varying excitation frequencies. It is demonstrated that the obtained temperature inreases with increase of the defect diameter and decrease of its depth. The dependence of the temperature over the top surface of the defect on its location and orientation is also presented. The results indicate that we can detect the subsurface defect and estimate its depth and location by choosing a suitable coil-specimen configuration. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    First-principle investigation of the structural stability and electronic property of precipitates on the Cu-rich side of Cu-Ni-Si alloys
    Long Y.-Q.; Liu P.; Liu Y.; Jia S.-G.; Tian B.-H.
    2011, 16 (3):  266-271.  doi: 10.1007/s12204-011-1141-4
    Abstract ( 8 )   PDF (382KB) ( 23 )  
    The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method. The negative formation heats and the cohesive energies of these precipitates were estimated with electronic structure calculations, and their structural stability was also analyzed. The results show that δ-Ni2Si, γ-Ni5Si2 and β-Ni3Si precipitates all have great alloying ability and structural stability, which, after comparing their density of states (DOS), is found attributed to the pseudogap effect near the Fermi level (EF) and strong hybridization between the Ni-3d and Si-3p states. Compared with the other two precipitates, the δ-Ni2Si precipitate has the greatest structural stability, which is resulted from its lower DOS at EF and the main bonding peaks slightly moving to the low energy region. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Numerical simulation of fluid flow caused by buoyancy forces during vacuum arc remelting process
    Zhao X.-H.; Li J.-S.; Yang Z.-J.; Kou H.-C.; Hu R.; Zhou L.
    2011, 16 (3):  272-276.  doi: 10.1007/s12204-011-1142-3
    Abstract ( 10 )   PDF (777KB) ( 24 )  
    The metallurgical structure and composition of ingots which depend critically on the fluid motion within the molten pool during the vacuum arc remelting (VAR) process have important effect on the subsequent mechanical processes like forging, rolling and welding. In order to determine the fluid motion of molten pool, a 2D finite element model is established using ANSYS10.0 software, combined with the turbulent fluid flow and heat transfer. The fluid motion caused by thermo buoyancy forces is investigated at different VAR processes in the present study. The results indicate that the fluid flows symmetrically along the axis of the molten pool and clockwisely along the circle at the right pool's profile. It is also shown that the maximum velocity increases with increasing melting rate and a direct proportional relationship exists. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Effect of rotation speed on temperature field and axial shortening of inertia friction welded GH4169 joints by numerical simulation
    Chen L.; Li W.-Y.; Li J.-L.
    2011, 16 (3):  277-280.  doi: 10.1007/s12204-011-1143-2
    Abstract ( 10 )   PDF (582KB) ( 24 )  
    A 2D finite element model was established for inertia friction welding of GH4169 nickel-base superalloy based on the ABAQUS environment. The remeshing and map solution techniques were adopted to solve the problem of element distortion. The effect of rotation speed on the temperature field and axial shortening of joints was investigated. The results show that the interface temperature increases rapidly to higher than 900? within 1 s. and then, it increases slowly to a quasi-stable value. The axial shortening begins to augment quickly when a uniform interface temperature field has formed and the plasticized material is extruded from the interface to form an obvious flash. The rotation speed of the flywheel controls the welding process and has a significant influence on the temperature evolution and axial shortening of joints. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Simulation of tube forming process in mannesmann mill
    Lu L.; Wang Z.-X.; Wang F.-Z.; Zhu G.-Y.; Zhang X.-X.
    2011, 16 (3):  281-285.  doi: 10.1007/s12204-011-1144-1
    Abstract ( 18 )   PDF (3189KB) ( 24 )  
    The finite element method (FEM) is used for simulation of the tube piercing process in Mannesmann mill. The numerical model is described with taking into consideration thermal phenomena in metal during forming. The simulated results visualize dynamic distributions of mean stresses, temperature, velocity and shear stresses, especially inside the workpiece. On the basis of the basic parameters, the phenomenon in the piercing process is analyzed. The model is verified by comparing the values of calculated force parameters of the piercing process and those measured in laboratory conditions. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    High temperature indentation test to improve constitutive model for welding simulation
    Slimani A.; Rachik M.
    2011, 16 (3):  286-290.  doi: 10.1007/s12204-011-1145-0
    Abstract ( 16 )   PDF (619KB) ( 24 )  
    The high temperature gradients experienced during fusion welding lead to a local dilatation and metallurgical transformations that generate inhomogeneous plastic deformation, residual stresses and distortions in the welded parts which can affect the service life of the structures. To predict such residual stresses and distortions, finite element analysis is nowadays widely used. This work reports a 3D finite element model for welding simulation. The proposed model is based on semi coupled thermo-mechanical analysis using a double ellipsoidal model of heat source. Firstly, a disk heated in its central zone is investigated. Secondly the validation concerns the simulation of a fully 3D two pass butt weld. The idea in this work concerns the calibration of the heat source parameters with the help of the inverse analysis to improve the heat flow predictions. For the stress analysis, an annealing temperature is introduced to force the material to lose its hardening memory above a given temperature. The predicted residual stresses as well as the predicted distortions are found to be sensitive to the annealing temperature. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Computer simulation of microscopic stress distribution in complex microstructure using a phase field model
    Uehara T.
    2011, 16 (3):  291-295.  doi: 10.1007/s12204-011-1146-z
    Abstract ( 13 )   PDF (712KB) ( 24 )  
    Microscopic stress distribution in a metallic material which has complex microstructure is simulated using a phase field model. The fundamental equations which take into account the coupling effects among phase transformation, temperature and stress/strain are used, while thermal effects are neglected to focus on the volumetric change due to phase transformation in this paper. A two-dimensional square region is considered, and the evolution of microscopic stress and the resultant residual stress distribution are calculated using the finite element method. As the phase transformation progresses and grains grow larger, stress is generated around the growing interface. When a grain collides with another one, specifically large stress is observed. Residual stress is finally distributed in the microstructure formed, and apparently large stresses are retained along the grain boundaries. Subsequently, dependency of the stress distribution on microstructure pattern is investigated. First, variously sized square grains are tested, and it reveals that the maximum stress tends to decrease as the grain size becomes smaller. Next, the shapes of the grains are varied. As a result, the stress distribution is remarkably affected, while the maximum stress value does not change so much. More complicated grain arrangement is finally tested with eight or nine grain models. Then, it is revealed as a common feature that large stress is generated along the grain boundaries and that the stress distribution is dependent on the grain arrangement. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Analysis of stress and strain fields of laser cladding process on ring circular orbit
    Zhang P.; Ma L.; Yuan J.-P.; Cai Z.-H.
    2011, 16 (3):  296-301.  doi: 10.1007/s12204-011-1147-y
    Abstract ( 11 )   PDF (1752KB) ( 24 )  
    The cracking of coatings and the deformation of base frustrate the application of laser cladding technology especially on surface of the ring circular orbit. In order to solve the two problems above, the stress and strain fields of the laser cladding process on the ring circular orbit were analyzed through the finite-element method, based on the temperature field. The wedge module of the ring circular ring was the subject investigated. The calculating results show that during the cladding process the crank point tends to generate the transversal crack; the centre point on the coating/base interface tends to generate longitudinal crack; the intersecting edge of the coating and base tends to generate toe crack. Moreover, the cracking tendency of the outer marginal point is obviously greater than that of the inner marginal point. The rather high stress appears at the border position where the constraint exists, and the stress on the point in front of molten pool under the range of laser irradiation is large as well. And the displacement becomes larger as the cladding process proceeds. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Finite element modeling of hydrostatic stress distribution in copper dual-damascene interconnects
    Yuan G.-J.; Chen L.
    2011, 16 (3):  302-306.  doi: 10.1007/s12204-011-1148-x
    Abstract ( 14 )   PDF (1036KB) ( 24 )  
    Hydrostatic stresses of copper dual-damascene interconnects are calculated by a commercial finite element software in this paper. The analytical work is performed to examine the effects of different low-k (k is permittivity) dielectrics, barrier layer and aspect ratio of via on hydrostatic stress distribution in the copper interconnects. The results of calculation indicate that the hydrostatic stresses are highly non-uniform throughout the copper interconnects and the highest tensile hydrostatic stress exists on the top interface of lower level interconnect near via. Both the high coefficient of thermal expansion and the low elastic modulus of the low-k dielectrics and barrier layer can decrease the highest hydrostatic stress on the top interface, which can improve the reliability of the copper interconnects. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Optimization of pellet induration process parameters in rotary kiln using simulation results
    Feng J.-X.; Xie Z.-Y.; Lü Y.-Y.; Xu J.-H.; Zhang Y.-M.; Yang J.-B.
    2011, 16 (3):  307-311.  doi: 10.1007/s12204-011-1149-9
    Abstract ( 7 )   PDF (814KB) ( 23 )  
    In order to optimize the pellet induration process parameters of rotary kiln, a mathematical model is developed and solved by using commercial software FLUENT. Orthogonal regression has been performed by using the simulated results of the pellet induration in rotary kiln. The functional relations between pellet induration quality and process parameters are obtained. The main parameters that affect the thermal process are also discussed. The results show that the high temperature zone is longer and the local high-temperature could be avoided while the velocity difference decreases between the secondary air and the carbon particle, which leads to more uniformed temperature distribution and better induration quality. The work gives a right direction on improving of pellet production. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Development and application of thermal mathematical model of iron ore pellet bed in grate
    Feng J.-X.; Liang K.-L.; Zhang C.; Xu J.-H.; Zhang Y.-M.; Yang J.-B.
    2011, 16 (3):  312-315.  doi: 10.1007/s12204-011-1150-3
    Abstract ( 9 )   PDF (659KB) ( 24 )  
    Based on the analysis of heat transfer mechanics, physical and chemical change of pellet drying and preheating process in grate, the mathematical model is established and solved by three-diagonal matrix algorithm. With Visual Basic 6.0 a simulation software is developed. The model is verified by measurements at a domestic pellet plant, and the temperature distribution of pellet bed is gained. Meanwhile, the influence of different operation parameters on the pellet thermal process is studied. The results can be taken as a basis of practical production control and the grate optimizing design. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Modeling on directional solidification of solar cell grade multicrystalline silicon ingot casting
    He L.; Wang G.; Rong Y.-M.
    2011, 16 (3):  316-319.  doi: 10.1007/s12204-011-1151-2
    Abstract ( 11 )   PDF (556KB) ( 24 )  
    Solar energy is considered as one of the best alternative energy in the future. Multicrystalline silicon ingot casting is the main production process for major supply of solar cell. However, the casting process cannot be understood clearly because of some difficulties, such as enclosed furnace, long cycle time of production and so on. In this paper, an integrated model, including casting process analysis, quality prediction and production parameters optimization, is proposed and the preliminary results are acquired. The framework of the proposed model is introduced and the numerical simulation results on the temperature field and grain growth process are also given out and discussed. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Numerical analysis of braking discs for a taurus class locomotive
    Oder G.; Šamec B.; Lerher T.; Potrě I.
    2011, 16 (3):  320-323.  doi: 10.1007/s12204-011-1152-1
    Abstract ( 12 )   PDF (834KB) ( 24 )  
    This paper shows the thermal and stress analysis of the worn brake disc for a Taurus class locomotive. The numerical analyses are carried out under the experimental testing program, Prüfprogramm No. 5, which is adjusted for this type of locomotives by UIC CODE 541-3. The simulations results under mentioned program show the most unfavorable case of braking. The numerical analysis is done with the finite element method (FEM), using ABAQUS software. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Study on bending conditions of plate in coil box
    Yu X.-L.; Yang Q.; Jiang Z.-Y.; Yuan H.-S.
    2011, 16 (3):  324-328.  doi: 10.1007/s12204-011-1153-0
    Abstract ( 16 )   PDF (821KB) ( 24 )  
    In a coil box between the roughing and finishing stands on a hot strip mill, a problem has been encountered that the entry region of the plate touches the bending rolls and deforms. As a result, the defective coil occurs. The condition of plate bending, which forms a new deformation feature in coiling, is analyzed. In this paper, the authors focus on the research of the effects of coiling parameters, such as the thickness of plate, roll speed and feeding speed of plate in coil box, and on specific plate bending. A finite element method is developed to simulate this coiling process. Based on numerical simulation, the effects of the coiling parameters on the mechanics and deformation of the bending plate are obtained. Numerical simulation tests have verified the validity of the developed model. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Numerical simulation on temperature and stress fields in beryllium during cutting process
    Dong P.; Zhang P.-C.; Li R.-W.
    2011, 16 (3):  329-332.  doi: 10.1007/s12204-011-1154-z
    Abstract ( 15 )   PDF (482KB) ( 24 )  
    The temperature and stress fields in beryllium during high speed cutting process were studied by employing a thermo-mechanically coupled finite element method (FEM). The results show that the temperatures in beryllium increase only a little during the cutting process. Both of the residual stresses for along and normal to the cutting direction are tensile stresses in the surface of beryllium after cutting. The cutting force and thrust force are about 280 and -250 kN/m at the steady stage, respectively. The main effects of coolant on the cutting process are to decrease the friction coefficient and heat between the tool and the workpiece, so to reduce the temperature, but almost no effects are made for stress. This study is helpful to enhance the understanding for stress formation and optimize the process parameters of beryllium. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Numerical simulation of non-destructive testing of stainless steel composites plate by infrared thermography
    Li G.-H.; Hu Y.; Fang J.-Y.; Gu X.-Y.; Gao J.-C.; Wu M.
    2011, 16 (3):  333-336.  doi: 10.1007/s12204-011-1155-y
    Abstract ( 9 )   PDF (423KB) ( 24 )  
    The non-destructive testing (NDT) of debonding in stainless steel composites plate (SSCP) is performed by infrared thermography, finite element analysis (FEA) software ANSYS is taken as the simulative tool, and 2D simulative model has been set up to investigate effect of the thickness of coating and/or substrate on the detectibility of debonging in SSCPs. Two parameters, namely the maximum defect temperature difference and defect appearing index, are defined to evaluate the detectivity of defects, and their computational methods and formulas are given respectively. The preliminary changing tendency of the maximum defect temperature difference and defect appearing index with the thickness of coating and/or substrate is found by numerical simulation. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Monte Carlo model in metal recrystallization simulation
    Zhang J.-X.; Wen H.; Liu Y.-T.
    2011, 16 (3):  337-342.  doi: 10.1007/s12204-011-1156-x
    Abstract ( 12 )   PDF (2243KB) ( 24 )  
    Some new advices are proposed for Monte Carlo model of recrystallization annealing simulation, including an additional recovery process, a new stored energy distribution, a more advanced nucleation model and a conversion probability of site orientation. Then a Monte Carlo model is established absorbing the above improvements, and used to isothermal annealing simulation of 1060 pure aluminum cold-rolled sheet. For contrast, a recrystallization annealing experiment of 1060 pure aluminum is carried out at the same time. The results show that the 1060 aluminum alloy in the annealing experiment produces obvious recrystallization, and the grain morphology of recrystallization is similar to isometric. The new model can effectively simulate the nonhomogeneous nucleation process and the microstructure evolution of 1060 industrial pure aluminum in annealing, and the simulated recrystallization kinetics curve is similar to the theoretical curve. The Avrami exponent coincides with the experimental result but is lower than the theoretical value of 2. As the Monte Carlo model does not consider the preferential growth orientation, some simulated results are not completely consistent with that from experiments. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Fractal studies on primary phase morphology of TA15 titanium alloy after hot compressive deformation
    Yang X.-W.; Zhu J.-C.; Lai Z.-H.; Liu Y.; Zhan J.-J.
    2011, 16 (3):  343-346.  doi: 10.1007/s12204-011-1157-9
    Abstract ( 12 )   PDF (1716KB) ( 24 )  
    The goal of this study is to establish relationships between the hot compression deformation behaviors and the fractal dimension of primary phase morphology of TA15 titanium alloy using the analytical methods of metallurgical microscope and transmission electron microscope coupled with box-counting dimension method. The hot compression deformation behaviors vary with decreasing fractal dimension owing to the change of microstructure caused by different parameters of the hot compressive deformation. The results indicate that TA15 alloy shows dynamic recrystallization characteristics at deformation temperature lower than 850°C while fractal dimension exhibits a moderate decreasing trend with the temperature increasing, and shows dynamic recovery characteristics at deformation temperature higher than 850°C while fractal dimension reduces rapidly with the temperature increasing. The fractal dimension displays non-linear relationship with fraction of primary phase and with aspect ratio of primary phase. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Three-dimensional numerical simulation of splat formation on substrates in plasma spraying
    Cui C.-W.; Li Q.
    2011, 16 (3):  347-351.  doi: 10.1007/s12204-011-1158-8
    Abstract ( 14 )   PDF (566KB) ( 24 )  
    Plasma sprayed coatings are built up by the accumulation of splats formed by the impacting, spreading and solidifying of molten droplets on the substrate. A three-dimensional computational model including heat transfer and solidification is established to simulate the formation process of a single splat using the computational fluid dynamics (CFD) software, FLUENT. The fluid flow and energy equations are discretized and solved according to typical finite volume method on an unstructured grid. A volume of fluid (VOF) tracking algorithm is used to track the droplet flow with free surface. In order to understand the splat formation mechanism, the process of splat formation caused by impacting and spreading of a molten nickel droplet on a polished mild steel surface is simulated. On this basis, the simulations of impact of a molten droplet on substrate with different conditions including the surface morphology, thermal conductivity, initial temperature of the substrate and the thermal contact resistance are presented. The results clearly show the effect of those parameters on the shape of the final splat and splash behaviors. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Computer simulation of the continuous annealing recrystallization for cold-rolled strip in galvanizing line
    He J.-G.; Wen J.-B.; Zhou X.-D.; Li X.-D.
    2011, 16 (3):  352-355.  doi: 10.1007/s12204-011-1159-7
    Abstract ( 11 )   PDF (362KB) ( 24 )  
    The continuous heating transformation program is developed to investigate the influence of continuous annealing technological parameters on recrystalization for cold-rolled strip in galvanizing line. This program can be used for the calculation of the continuous annealing temperature field of strip steel, determination of the start and end time of recrystallization in continuous heating process, and procurement of the continuous heating transformation diagram. The temperature field for continuous annealing is simulated by means of finite difference method. Based on the Scheil superposition principle, the continuous heating transformation curve is obtained by using time temperature transformation (TTT) curve which is measured experimentally. The developed program has been used in practice, and the strip speed on production line increases by more than 10%. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Phase-field modeling of free dendritic growth in binary alloy under forced flow
    Xiao R.-Z.; Wang Z.-P.; Zhu C.-S.; Feng L.; Li W.-S.
    2011, 16 (3):  356-359.  doi: 10.1007/s12204-011-1160-1
    Abstract ( 10 )   PDF (618KB) ( 23 )  
    A phase-field model (PFM) coupling with phase field, flow field and diffuse equation is presented for simulating isothermal dendrite growth of a nickel-copper alloy under a forced flow. Based on the finite difference method with uniform grid, the C programming code is implemented to complete the phase-field simulations. The simulation results indicate that the interfacial morphology, the symmetry of dendrite formation, the tip growth velocity and the concentration distribution are strongly influenced by the fluid flow. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Influence of soaking temperature on microstructure of multi-pass compression deformation for low carbon steels
    He Y.-L.; Wu X.-Y.; Zhu N.-Q.; Zhang M.; Lin D.-W.; Li L.
    2011, 16 (3):  360-363.  doi: 10.1007/s12204-011-1161-0
    Abstract ( 9 )   PDF (1097KB) ( 23 )  
    The influence of soaking temperature on microstructure of high temperature multi-pass compression deformation for two low carbon steels (steel A: w C = 0.032% and wMn = 0.25%; steel B: w C = 0.165% and wMn = 0.38%) is studied on the thermal-mechanical simulator in order to rationalize the hot-rolling schedule of low-carbon steel and to promote the low-temperature heating technology. The results show that the microstructures of steel A are almost not affected by reducing soaking temperature, but the acicular ferrite forms in steel B when the soaking temperature is reduced from 1 200 to 1 170?, due to its smaller initial austenite grain size according to recrystallization kinetics theory. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Viscous micropump simulation by particle/continuum methods
    Wang S.; Luo X.-L.; Lei K.-B.; Gu Z.-L.; Kase K.
    2011, 16 (3):  364-367.  doi: 10.1007/s12204-011-1162-z
    Abstract ( 15 )   PDF (642KB) ( 24 )  
    A novel viscous micropump consisting of a cylindrical rotor eccentrically placed inside a microchannel is simulated by the two Volume-CAD (V-CAD) framework-based flow solvers, i.e., the direct simulation Monte Carlo (DSMC) package (named as V-DSMC) and the Navier-Stoke solver (named as V-Flow). V-DSMC is used in the case of the pump applied to gas, while V-Flow is applied to model the pump in the case of liquid working medium. The pumping performance curves under different liquid media with the variation of Reynolds number, as well as under different eccentricity factors are obtained. The performance and the flow filed characteristics are very sensitive to the tangential momentum accommodation coefficient in the case of gas medium. Three recirculations exist in the flow field, and the sizes of recirculation are different at the different operating points in a performance curve. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Effects of crack opening angle and external loads on reliability of welded pipe with circumferential crack
    He B.-L.; Yu Y.-X.; Huo L.-X.; Zhang Y.-F.
    2011, 16 (3):  368-371.  doi: 10.1007/s12204-011-1163-y
    Abstract ( 13 )   PDF (209KB) ( 24 )  
    The reliability of welded pressure pipe with circumferential surface crack was calculated by using 3D stochastic finite element method. This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method. The calculation of reliability was based on 3D elasticplastic stochastic finite element program which was developed by ourselves. The effects of variables such as fracture toughness, bending moment and depth of the circumferential surface crack on the structure reliability were also discussed. The calculation results indicate that the crack opening angle has certain effect on the reliability of the welded pipe. When the mean value of bending moment is 10 kN·m, with the crack opening angle increasing from 30° to 180°, the failure probability of the welded pipe changes from 3.837 9×10-8 to 3.694 3×10-6. When the mean value of bending moment is 15 kN·m, with the crack opening angle increasing from 30° to 180°, the failure probability of the welded pipe changes from 3.986 5×10-6 to 1.936 7×10 -3. The bending moment has great effect on the reliability of the welded pipe. When the mean value of moment is changed from 10 to 15 kN·m, the failure probability of the welded pipe increases dramatically for the same circumferential crack opening angle. Regardless of changing of moment, the pipe has higher reliability if the crack opening angle is less than 60?. The method has put forward a new way for safety assessment of welded pipe with circumferential surface crack. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Usage of simulated annealing algorithm in design of optical thin film
    Wang W.-L.; Rong X.-H.
    2011, 16 (3):  372-374.  doi: 10.1007/s12204-011-1164-x
    Abstract ( 9 )   PDF (290KB) ( 24 )  
    Simulated annealing algorithm is a mathematic model, which imitates the physical process of annealing. And optical thin film is widely used in many industry. Its design is difficult and can be regarded as an optimization problem. In this paper, we use the simulated annealing algorithm to design an edge filter, which is composed of 20 dielectric thin film layers with TiO 2 and SiO2. The simulated annealing algorithm is a very robust algorithm.© Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Numerical simulation of thermal and iron ore reduction conditions in pre-reduction shaft furnace based on reducing gas composition and temperature
    Xu J.; Wu S.-L.; Guo X.-Y.; Kou M.-Y.
    2011, 16 (3):  375-379.  doi: 10.1007/s12204-011-1165-9
    Abstract ( 9 )   PDF (561KB) ( 24 )  
    Based on the principles of mass, momentum and heat transfers between the reducing gas and the iron ore solid, a two-dimensional mathematical model for above two phases is established to study the influences of reducing gas composition on thermal and reduction conditions in pre-reduction shaft furnace with the temperature ranging from 1 023 to 1 223K. Due to the strong endothermic effect of iron ore reduction participated by hydrogen (H2), increasing the ratio of carbon monoxide (CO) to H2 enlarges high temperature zone under present calculation conditions, thus improves reduction efficiency inside the furnace. In addition, replacing of the reducing gas with an appropriate proportion of nitrogen (N2) featuring the same temperature has a potential to reduce fuel consumption by as much as 6.5% while the products of similar quality are yielded. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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    Histologic changes in the sinus membrane after maxillary sinus augmentation with simultaneous implant placement using engineered bone graft material
    Lu J.-Y.; Zhao W.; Zhu H.; Qu X.-H.; Zou D.-R.
    2011, 16 (3):  380-384.  doi: 10.1007/s12204-011-1166-8
    Abstract ( 17 )   PDF (829KB) ( 24 )  
    The aim of the study was to analyze the histologic and ultrastructural changes after maxillary sinus augmentation with simultaneous implant placement using engineered bone graft material. In this study, calcium phosphate cement (CPC) scaffolds combined with goat bone marrow stromal cells (BMSCs) were used to fill goat sinus floor space after maxillary sinus floor elevation with simultaneous implant placement comparing with those not filled any grafted materials and used as controls. After a healing period of 3 months, the goat maxillary sinus membrane was examined using light microscopy and scanning electronic microscopy. The results showed that the connective tissue thickness and the epithelium thickness of mucosa were not statistically significant difference between two groups. The tissue engineered bone complex might be an ideal graft for the sinus floor elevation and have no influence on the sinus membrane under the histological and ultrastructural observation. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.
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