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30 April 2011, Volume 16 Issue 2 Previous Issue    Next Issue
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Research on mechanical properties of 22MnB5 steel quenched in a steel die He L.-F.; Zhao G.-Q.; Li H.-P.; Xiang N. 2011, 16 (2):  129-132.  doi: 10.1007/s12204-011-1106-7 Abstract ( 17 )   PDF (903KB) ( 31 )   22MnB5 is one of the most typical hot stamping boron steels. In order to study the effect of austenitizing temperature and holding time on the mechanical properties of hot stamping boron steel 22MnB5, a series of quenching process are done. The tensile strength and hardness of 22MnB5 samples are measured. The results show that 22MnB5 has a good quenching performance, and the tensile strength and hardness of samples quenched in a water-cooled steel die are similar to those of water quenching. The higher tensile strength and HRC hardness are achieved when austenitizing at temperatures of 880-910 °C. Holding at 910 °C for 5 min and then quenching gives rise to a better combination of tensile strength, hardness and ductility. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Effect of remelting current on molten pool profile of titanium alloy ingot during vacuum arc remelting process Yang Z.-J.; Kou H.-C.; Zhao X.-H.; Li J.-S.; Hu R.; Chang H.; Zhou L. 2011, 16 (2):  133-136.  doi: 10.1007/s12204-011-1107-6 Abstract ( 8 )   PDF (1145KB) ( 30 )   The performance of vacuum arc remelting (VAR) ingot depends largely on ingot structure and chemical uniformity, which are strongly influenced by molten pool profile that is influenced by VAR process. To better understand the effect of remelting current on molten pool profile of titanium alloy ingot during VAR process, a 3D finite element model is developed by the ANSYS software. The results show that there are three remelting stages during VAR process when the remelting current is 2.0 kA. The molten pool depth increases gradually from 30 to 320 s, then the change of molten pool depth is very small during the steady state stage from 320 to 386 s, and lastly the molten pool depth becomes shallow after 386 s. The melting rate and temperature of superheat increase with the remelting current increasing, which leads to the augment of molten pool volume. In the end, the total remelting time and steady state molten pool time decrease with the melting current from 1.6 to 2.8 kA. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Integrated fluid-thermal-structural numerical analysis for the quenching of metallic components Gao W.-M.; Fabijanic D.; Hilditch T.; Kong L.-X. 2011, 16 (2):  137-140.  doi: 10.1007/s12204-011-1108-5 Abstract ( 18 )   PDF (552KB) ( 29 )   The quenching of a metal component with a channel section in a water tank is numerically simulated. Computational fluid dynamics (CFD) is used to model the multiphase flow and the heat transfer in film boiling, nucleate boiling and convective cooling processes to calculate the difference in heat transfer rate around the component and then combining with the thermal simulation and structure analysis of the component to study the effect of heat transfer rate on the distortion of the U-channel component. A model is also established to calculate the residual stress produced by quenching. The coupling fluid-thermal-structural simulation provides an insight into the deformation of the component and can be used to perform parameter analysis to reduce the distortion of the component. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Numerical simulation of multi-pass rolling force and temperature field of plate steel during hot rolling Zeng B.; Wu J.; Zhang H.-H. 2011, 16 (2):  141-144.  doi: 10.1007/s12204-011-1109-4 Abstract ( 13 )   PDF (517KB) ( 28 )   Rolling force and temperature field are important parameters in the hot rolling process of plate steel. Most researchers use ANSYS/LS-DYNA and MSC.Marc to simulate the hot rolling process, however, software DEFORM-3D is not used widely in this field. Therefore, in this study, the commercially available finite element analysis software DEFORM-3D is used to simulate the distribution of rolling force, stress-effective, strain-effective and temperature field during the hot rolling process of plate steel with the size of 0.220m×2.070m×1.904m. Both the simulated rolling force and temperature of the multi-pass are compared with the measured results. It is shown that the simulated values by the finite element method are approximate to the measured values in the hot rolling of plate steel. So the simulation can provide an important reference and optimization to make rolling process and parameters in steel factory. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Numerical simulation of macrosegregation during steel ingot solidification using continuum model Wang L.; Shi W. 2011, 16 (2):  145-148.  doi: 10.1007/s12204-011-1110-y Abstract ( 13 )   PDF (861KB) ( 29 )   A continuum model is adopted to study the macrosegregation phenomena during solidification of large steel ingots. Evolution of temperature, melt velocity, and compositional concentration field during a 22 t steel ingot solidification are illustrated by using the finite volume method. Numerical results of temperature distribution are validated by experiments. The influence of local permeability relates to the friction that the melt experienced in mushy region is investigated. It is shown that the continuum model is able to predict the temperature field, and the variation of permeability obviously affects the melt flowing behavior and the final compositional distribution. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Numerical analysis of railway brake disc Šamec B.; Oder G.; Lerher T.; Potrč I. 2011, 16 (2):  149-151.  doi: 10.1007/s12204-011-1111-x Abstract ( 12 )   PDF (543KB) ( 31 )   A certain number of railway brake discs made of gray cast iron, showed the presence of small cracks only after a few thousand kilometers. To investigate main causes of a brake disc failure, numerical analysis was done by using ABAQUS software. Numerical analysis resulted from a physical model of heat flux in dependence of braking time. Physical model was applied considering all demands and presumptions given by industry representatives. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Computer modeling and validations of steel gear heat treatment processes using commercial software DANTE Li Z.-C.; Ferguson B.L. 2011, 16 (2):  152-156.  doi: 10.1007/s12204-011-1117-4 Abstract ( 21 )   PDF (1056KB) ( 28 )   The heat treatment process of a gear made of AISI 9310 carburized steel is modeled using the commercial heat treatment simulation software DANTE. Both carburization and quenching processes affect the residual stress distribution and distortion of heat-treated parts, which are important to service quality and fatigue life. DANTE/VCARB is used to design the boost/diffuse schedule of a vacuum carburization process. Oil quenching is modeled following the vacuum carburization process. Thermal gradient and phase transformation are two main sources of distortion and residual stresses in quenched parts. The relation of the carbon distribution, thermal gradient, and phase transformations during quenching is studied through the gear modeling example. Because of geometry, the residual stress distribution after quenching is non-uniform along the gear surface. In general, the root fillet has higher residual compression than either the root or tooth face locations after traditional oil quenching of carburized gears. The predicted residual stresses from the oil quenching model are imported into a single tooth fatigue bending model. The gear stresses under bending load indicate the possible cracking locations during the bending fatigue test. The importance of heat treatment residual stresses during gear design is pointed out, and it is commonly ignored in the gear design and manufacturing industry. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Numerical analysis of unconventional forging process of hollowed shaft from Ti-6Al-4V alloy Gontarz A.; Pater Z.; Tofil A. 2011, 16 (2):  157-161.  doi: 10.1007/s12204-011-1118-3 Abstract ( 18 )   PDF (927KB) ( 30 )   This paper presents theoretical analysis of unconventional forging process of hollowed shaft from Ti-6Al-4V alloy in a three-slide forging press. This method in comparison with other metal forming methods allows for obtaining of hollowed products. The designed process is verified theoretically by means of numerical simulations based on finite element method with assumption of 3D state of strain. The following factors are considered in the analysis: material flow kinematics, strain distribution, temperature distribution and force of process. On the basis of results, it is stated that the application of designed technology allows for obtaining of a product of assumed quality. A comparison is made between material consumption in analyzed process and material consumption in typical metal forming methods, also in used at present technology of shaft manufacturing by machining only. It is stated that the application of forging in the three-slide forging press allows for a considerable decrease of manufacturing costs due to material savings and decrease of labor consumption of operations at finishing. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Analysis of the cross-wedge rolling process of toothed shafts made from 2618 aluminium alloy Pater Z.; Gontarz A.; Tofil A. 2011, 16 (2):  162-166.  doi: 10.1007/s12204-011-1119-2 Abstract ( 12 )   PDF (962KB) ( 29 )   The paper presents the results of a thermo-mechanical analysis of the rolling two stepped shafts. One of the shafts has a toothed step with skew teeth, while the other has a worm winding in the shape of a trapezoidal screw. The shape of the rolling tools resembles that of the tools used in the Roto-Flo rolling method; yet unlike in Roto-Flo, the shafts are hot-rolled and no centres are used to stabilize the position of the workpiece during the forming process. For the calculations made with use of the DEFORM-3D process simulation system it has been assumed that the rolled shafts are made from 2618 aluminium alloy. As a result of the calculations made, it has been found that the toothed stepped shafts can be formed in one pass by means of the cross rolling process. Additionally, the temperature and strain distribution in the rolled product have been determined as well as some data concerning the forces which are necessary for the rolling process have been obtained. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Calculation on the incubation period of proeutectoid ferrite transformation for Si-Mn TRIP steel Tang G.-B.; Peng N.-Q.; Liu Z.-D. 2011, 16 (2):  167-172.  doi: 10.1007/s12204-011-1112-9 Abstract ( 12 )   PDF (526KB) ( 28 )   The incubation period of proeutectoid ferrite transformation for Si-Mn transformation induced plasticity (TRIP) steel has been calculated by the Aaronson's incubation period model for transformation. The influences of chemical compositions and hot deformation of austenite on the incubation period have been taken into consideration in the calculation, and some parameters have been proposed and validated with the measured time temperature transformation (TTT) curves from dilation tests. The calculation results show that it is essential to take into account of the effect of solute atoms on the interfacial energy in the austenite grain boundaries. For hypoeutectoid steel, the incubation period of ferrite transformation increases with the increase of C and Mn contents, and C has a greater impact than that of Mn, while the incubation period of ferrite transformation decreases with the increase of Si content. Hot deformation shortens the incubation time and promotes austenite to ferrite transformation. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Explore the possibility of forming fcc high entropy alloys in equal-atomic systems CoFeMnNiM and CoFeMnNiSmM Zhang C.-H.; Lin M.-H.; Wu B.; Ye G.-X.; Zhang L.-K.; Chen T.; Zhang W.-J.; Zheng Z.-H.; Li Q.; Shao Y.-Q.; Zhou B.-Y.; Wang C. 2011, 16 (2):  173-179.  doi: 10.1007/s12204-011-1113-8 Abstract ( 15 )   PDF (591KB) ( 29 )   The multi-principal high-entropy alloys (HEAs) are promising new alloys. However, it is a challenge to screen out the suitable composition from the diverse combinations. Referring to the prototype AuCu3 with AB 3-L12 structure, where it becomes a face-centered cubic (fcc) structure if element A and B are the same element, the site occupying tendencies of the elements and thermodynamic functions are predicted by using the sublattice model supported with first-principles total energy calculations. By considering the Gibbs energy of formation and the configurational entropy, the fcc HEAs in available literatures are examined, and the results of the quinary system with equal-atomic composition CoFeMnNiM and the hexbasic system with equal-atomic composition CoFeMnNiSmM are reported, respectively, where the element M is selected from the rest of the periodical table. When M=Cr, Zn, Ru, Rh, Pd, Re, Os, Ir, or Pt in the quinary systems CoFeMnNiM and when M=Ru, Pd, or Pt in the hexbasic systems CoFeMnNiSmM, respectively, the alloys are recommended to be potential fcc HEAs. The new approach opens a new way to mine the rich ores of HEAs. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Calculation on the solid solution forming enthalpies of Re-Mo-Ti gradient alloy in thermodynamics Yang S.-L.; Lou S.-N. 2011, 16 (2):  180-185.  doi: 10.1007/s12204-011-1114-7 Abstract ( 13 )   PDF (440KB) ( 28 )   The idea about preparation of Re-Mo-Ti alloy is put forward because of applications of Re and Mo-Re alloys in aerospace. Basing on the thermodynamics theory, the feasibility of developing a new high temperature alloy Re-Mo-Ti is investigated. The solid solution forming enthalpies of binary alloys Re-Ti, Mo-Ti and Mo-Re are calculated with the Miedema thermodynamics theory. The Miedema theory of binary alloy can be used in ternary alloy through Kohler model or Toop model. The calculated results show that the forming enthalpies of binary alloys Re-Ti, Ti-Mo and Re-Mo are negative, which indicates that binary alloys Re-Ti, Ti-Mo and Re-Mo can form solid solution in wider component area. The forming enthalpies of Re-Mo-Ti ternary alloy are still negative and smaller than those of binary alloys Re-Ti, Ti-Mo or Re-Mo, which indicates it is possible to form large solid solution graph area among ternary alloys of Ti, Mo, Re elements. It is feasible to develop a new high temperature material in thermodynamics, in this material Re-Mo-Ti solid solution as base phase, and the Ti5Re24 intermetallic compounds or interphase ω (Ti4Mo3) as strengthening phase. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Monte Carlo simulation of B2-L21 ordering transitions in Au-Cu-Al alloy systems Ding H.; Xu B.; Ni C.; Wang J.-Y.; Jin X.-J. 2011, 16 (2):  186-189.  doi: 10.1007/s12204-011-1115-6 Abstract ( 14 )   PDF (358KB) ( 29 )   The B2-L21 ordering transitions in Au-Cu-Al shape-memory alloys are studied by the Monte Carlo exchange simulations, where a set of the first, the second and the third nearest-neighbor mixing potentials for Cu-Al in the Au-Cu-Al alloys are calculated from first principals using the Connolly-Williams methods. To ensure the phase stability of the β-Au-Cu-Al, the investigation includes the range of compositions Au2Cu1-x Al1+x (-0.15 ≤ x ≤ 0.15). The B2-L21 transition temperatures are predicted, and are in agreement with the experimental results. The atomic ordering around vacancy of the L21 structure is further discussed. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Simulating mechanical behavior of porous materials by homogenization method Yu N.; Zhang W.-M. 2011, 16 (2):  190-194.  doi: 10.1007/s12204-011-1116-5 Abstract ( 14 )   PDF (538KB) ( 29 )   In this study, a homogenization method is employed to determine the values of effective elastic modulus for BaZrO3 which is a promising candidate material for electrolyte in solid oxide fuel cell (SOFC). Comparison between the homogenization and the analysis data reveals that the difference becomes significant with increasing of porosity when upper 20%. The empire mechanic behavior in a typical planar fuel cell is evaluated using finite element method (FEM). Large stress gradient occurs in vicinity of the interface of the electrolyte and the cathode due to theirs mismatch of thermal expansion coefficient (TEC). Moreover, local processing results reveal that microscopic stress concentration around pore near the interface of the electrolyte and the cathode in the cell perhaps produces cracks which may lead to the fail of the electrolyte and the lower energy convention efficiency. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Finite element simulation of rod and wire continuous rolling Zhang L.-W.; Yue C.-X.; Yuan S.-Y.; Ruan J.-H.; Gu S.-D.; Gao H.-J. 2011, 16 (2):  195-198.  doi: 10.1007/s12204-011-1120-9 Abstract ( 19 )   PDF (610KB) ( 30 )   This paper discusses the application of several techniques involved in the development of the 3D finite element (FE) models of rod and wire continuous rolling process. The FE models are implemented into the FE-program MSC.Marc and used to investigate the thermal and mechanical behavior of billet during the rolling process. All nonlinear equations included in the models are solved by the static and dynamic procedures, respectively. Data transfer technique is proposed to keep the continuity of simulation results. And the computational time of static procedure is significantly reduced by using a rigid pushing body. In all models, the constant time step method and the auto time step method are respectively used to define time step for the solution of equations. Simulation results of the models with different time step methods are compared. And comparison between calculated values and measured ones of the temperature at the surface of billet shows the validity of the FE models. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Simulation of large forging flat-anvil stretching process and its optimization Chen K.; Yang Y.-T.; Shao G.-J.; Liu K.-J. 2011, 16 (2):  199-202.  doi: 10.1007/s12204-011-1121-8 Abstract ( 16 )   PDF (556KB) ( 29 )   In this paper, a kind of mathematic method for optimizing stretching process of large forgings is proposed. Distributions of effective strain within forged ingots is described by a Gauss function, which is obtained from the simulation of flat-anvil stretching process. Successive stretching is expressed by the superimposing Gauss functions. Optimized stretching process, with both homogeneous and certain strain in the center of forgings, is presented by derivation of this function. The relationship between effective strain and the values of feed is obtained during the successive stretching with a rotation angle of 90° and a feed displacement of 1/2 anvil width. The optimization result is verified by finite element simulation. Optimized value of feed obtained using this method can ensure both uniformity and forging penetration. It provides mathematic model and theoretic basis of optimizing large forging stretching process. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Research on voids deformation welding condition for manufacturing of heavy forgings Huang H.-G.; Xu S.-M.; Wang W.; Du F.-S. 2011, 16 (2):  203-208.  doi: 10.1007/s12204-011-1122-7 Abstract ( 10 )   PDF (904KB) ( 27 )   Crushing and diffusion welding are two critical healing stages of interior void defects in heavy forgings. The healing result depends on many factors during the forging process, such as stress, temperature, deformation and type of material, while the void diffusion welding condition is still not well known at the present. This paper is concerned with the deformation welding condition of the closed void interface in heavy ingot during the hot forging process. A void crushing experiment is carried out to recognize the microstructure of the closed void interface. According to the healing mechanism at high temperature, a new physical simulation model is setup to study the deformation welding process of the closed void interface based on the theory of atom diffusion and the interface contact mechanics prototype. Compared with the experimental results, the influence of deformation degree, forming temperature and holding time on the welding quality is discussed, and then the deformation welding condition of closed void interface is presented. The proposed condition helps to improve forging technology and product quality. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Numerical analysis of material properties in deformation of near hemispherical shells Zhao X.; Chang H.; Tang B.; Zhang X.-H.; Kou H.-C.; Li J.-S. 2011, 16 (2):  209-213.  doi: 10.1007/s12204-011-1123-6 Abstract ( 10 )   PDF (795KB) ( 26 )   In this paper, the effects of hardening exponent, yield strength and elastic modulus on the deformability of near hemispherical shells are investigated by means of finite element method and orthogonal experiment design. The largest eccentric angle during the deformation process and thickness reduction after the deformation are introduced to estimate the deformability quantitatively according to the deformation characteristics of near hemispherical shells. The results indicate that the hardening exponent is the most influential parameter, followed by elastic modulus and yield strength. The shell exhibits good deformability when the hardening exponent and elastic modulus are in the range of 0.1-0.125 and 70-108 GPa, respectively. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Asymmetric deformation of near hemispherical diaphragm under uniform surface load Zhang X.-H.; Tang B.; Li J.-S.; Kou H.-C.; Zhou Z.-B.; Zhou L. 2011, 16 (2):  214-218.  doi: 10.1007/s12204-011-1124-5 Abstract ( 25 )   PDF (2490KB) ( 29 )   The asymmetric deformation and eccentricity problems of near hemispherical diaphragm under the uniform surface load are quantitatively characterized in the paper. The analysis is based on a 3D finite element analysis (FEA) model established according to elastic-plasticity and large displacement nonlinear finite element method. Besides, the deformation experiments are taken to validate the reliability of FEA model which shows that the simulation results are in good agreement with the experimental results. Then, three angle parameters, deflection angle β, circumvolving angle θ and distributing angle γ, are introduced and expressed to characterize the asymmetric deformation and eccentricity quantitatively. According to the angle parameters, the inversion processes of uniform thickness diaphragm and varying thickness diaphragm are calculated respectively. The inversion process of varying thickness diaphragm is much steadier than that of uniform thickness diaphragm. The present results show that the asymmetric deformation process can be characterized by curve of three angle parameters (β, θ, γ) exactly, the degrees of eccentricity can be indicated by the final value of deflection angle and the eccentricity position can be characterized by the final values of the three angle parameters. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Optimization of pellet production process parameters in grate using simulation results Feng J.-X.; Zhang Y.; Zheng H.-W.; Xu J.-H.; Zhang Y.-M.; Yang J.-B. 2011, 16 (2):  219-223.  doi: 10.1007/s12204-011-1125-4 Abstract ( 10 )   PDF (868KB) ( 27 )   The objective of this paper is to optimize the parameters of pellet drying and preheating process in grate. A mathematical model of drying and preheating is developed, and is verified by the experiments. Further, the operating parameters of wind temperature, wind speed, grate speed and bed depth etc. are investigated through the orthogonal method using the simulation results. And a relationship of drying, preheating effects and operating parameters is achieved. The results show that the optimization effect can be achieved in the given range when air velocity is about 3.0 m/s and temperature is about 300, 500, 800, and 1 100 °C in the updraft drying zone, downdraft drying zone, preheating I zone, and preheating II zone respectively. The work is help for saving energy and reducing emissions in pellet induration. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Timed quenching process for large-scale AISI 4140 steel shaft Zuo X.-W.; Zhou S.; Chen N.-L.; Liao B. 2011, 16 (2):  224-226.  doi: 10.1007/s12204-011-1126-3 Abstract ( 11 )   PDF (293KB) ( 27 )   The mechanical properties of AISI 4140 steel shaft with a diameter larger than 200 mm are difficult to meet the requirements and cracking occurs easily in water quenching, due to insufficient cooling ability of oil quenching. A new technology, named alternately timed quenching (ATQ), using water and air in turn as quenching media instead of oil or polymer aqueous solution, is applied to quench the large-scale AISI 4140 steel shaft. Two ATQ processes are determined with the aid of computer simulation first and the corresponding experiments are carried out consequently. The results show that the proposed technology can significantly reduce the surface cracking tendency and improve the mechanical properties in practical production of such large-scale shaft forgings. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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First-principles prediction of ductility in β-type Ti-Mo binary alloys Lai M.-J.; Xue X.-Y.; Zhou Z.-B.; Tang B.; Li J.-S.; Zhou L. 2011, 16 (2):  227-230.  doi: 10.1007/s12204-011-1127-2 Abstract ( 10 )   PDF (358KB) ( 27 )   Recent studies suggest that the ratio of the shear modulus (G) to the bulk modulus (B) and the Poisson's ratio (ν) are good indicators of ductility. Using the method of supercell and the first-principles pseudopotential plane-wave method, the G/B and ν of the β-type Ti-Mo binary alloys with Mo molar fraction (x Mo) ranging from 6.25% to 37.5% are calculated. The results show that the ductility of β-type Ti-Mo binary alloys first increases with increasing x Mo and reaches the maximum when x Mo is about 25%, and then reduces with more increasing x Mo. The charge density difference calculations suggest that the x Mo dependence of the ductility can be ascribed to the change of bonding characteristics between Ti and Mo atoms in the [111] direction. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Finite element analysis on the injection molding and productivity of conformal cooling channel Zheng Z.; Zhang H.-O.; Wang G.-L.; Qian Y.-P. 2011, 16 (2):  231-235.  doi: 10.1007/s12204-011-1128-1 Abstract ( 18 )   PDF (1605KB) ( 27 )   The study proves that the conformal cooling channel can overcome the disadvantages of the conventional cooling channel resulting from the limitation in complicated shape. The simulation analyses of the fragrance lamp with different cooling layouts show that the conformal cooling channel can offer a more uniform heat dissipation, lower volume shrinkage and shorter time to freeze than the conventional channel, which indicates significantly improvements in productivity and quality. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Characteristics of flow field around an underwater projectile with natural and ventilated cavitation Guo J.-H.; Lu C.-J.; Chen Y. 2011, 16 (2):  236-241.  doi: 10.1007/s12204-011-1129-0 Abstract ( 9 )   PDF (713KB) ( 27 )   The present simulation investigates the multiphase cavitating flow around an underwater projectile. Based on the homogeneous equilibrium flow assumption, a mixture model is applied to simulate the multiphase cavitating flow including ventilated cavitation caused by air injection as well as natural cavitation. The transport equation cavitating model and a local linear low-Reynolds-number turbulence model are incorporated to the equation system. The calculations are executed based on a suite of computational fluid dynamics code. The hydrodynamics characteristics of flow field under the interaction of natural cavitation and ventilated cavitation are analyzed. The results indicate that the ventilated cavitation numbers and the drag coefficient are relative to the natural cavitation numbers and gas flow rate in the multiphase cavitating flows. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Reliability research on fatigue life of spots of semi-submerged drilling unit Yan Y.-J.; Xu J.-Q. 2011, 16 (2):  242-246.  doi: 10.1007/s12204-011-1130-7 Abstract ( 12 )   PDF (1170KB) ( 25 )   Based on the calculated results of the simplified model of deep-water semi-submerged drilling unit, the model of deep-water semi-submerged drilling unit is built by reasonably simplifying. The large vertical cylinder (MacCamy-Fuchs) formula is modified according to this model, then the modified formula is utilized to obtain the wave load spectrum which acts on the columns of the semi-submerged drilling unit. By using ANSYS software, a spectrum analysis process is established to calculate the stochastic response spectrum of the model that is subjected to the wave load spectrum which has been calculated. Then the power spectral density of stochastic response of the key nodes can be obtained. Based on the Miner model and the first excursion failure criterion, the fatigue life reliability of the key nodes is calculated. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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A new method based on the non-isothermal kinetic equation to estimate the critical temperature of thermal explosion for energetic materials using non-isothermal DSC Zhang H.; Hu J.-Y.; Hu R.-Z.; Zhao F.-Q.; Gao H.-X. 2011, 16 (2):  247-251.  doi: 10.1007/s12204-011-1131-6 Abstract ( 14 )   PDF (172KB) ( 27 )   A method for estimating the critical temperature of thermal explosion for energetic materials using differential scanning calorimetry (DSC) measurement is derived from the Semenov's thermal explosion theory and the non-isothermal kinetic equation based on Harcourt-Esson's kinetic equation. The result obtained from this method coincides completely with that of the Hu-Yang-Liang-Wu method. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics

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Research on the method of shipping risk early-warning based on matter-element theory Zhang Y.; Wang B.; Tan Z.-D. 2011, 16 (2):  252-256.  doi: 10.1007/s12204-011-1132-5 Abstract ( 9 )   PDF (309KB) ( 27 )   The purpose of shipping risk early-warning is that some effective measures are taken to reduce risk probability before the risk brings heavy loss. The shipping risk has the dynamic characteristic, so the key of early-warning is to choice risk early-warning index correctly and evaluate risk grade quantitatively. According to the element extension theory, the rhombus inference model is applied to establish the index system. And the problem of risk grade evaluation can be solved by the assessment model of multi-index performance parameter, which is developed by the extension engineering method. Finally, the main shipping risks and their grades are identified by the example analysis based on the statistical data, which shows the effective and feasible of the shipping risk early-warning method. © 2011 Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg. Related Articles | Metrics