检索结果-南通市图书馆

computer simulation of the Indentation Creep Tests on Particle-Reinforced Composites

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2002年第4期18卷 335-340页

作者： Zhufeng YUE1,2)1)Department of Engineering Mechanics, Northwestern Polytechnical University, Xi’an 710072, China2)Institute of Materials, Ruhr University, 44780 Bochum, Germany Department of Engineering Mechanics Northwestern Polytechnical University Xi'an 710072 China Institute of Materials Ruhr University 44780 Bochum Germany

A systematical simulation has been carried out on the indentation creep test on particle-reinforced composites. The deformation, failure mechanisms and life are analyzed by three reasonable models. The following five factors have been considered simultaneously: creep property of the particle, creep property of the matrix, the shape of the particle, the volume fraction of the particle and the size (relative size to the particle) of the indentation indenter. For all the cases, the power law respecting to the applied stress can be used to model the steady indentation creep depth rate of the indenter, and the detail expressions have been presented. The computer simulation precision is analyzed by the two-phase model and the three-phase model. Two places of the stress concentration are found in the composites. One is ahead of the indentation indenter, where the high stress state is deduced by the edge of the indenter and will decrease rapidly near to a steady value with the creep time. The other one is at the interface, where the high stress state is deduced by the misfit of material properties between the particles and matrix. It has been found that the creep dissipation energy density other than a stress parameter can be used to be the criterion to model the debonding of the interfaces. With the criterion of the critical creep dissipation energy density, a power law to the applied stress with negative exponent can be used to model the failure life deduced by the debonding of interfaces. The influences of the shape of the particles and the matching of creep properties of particle and matrix can be discussed for the failure. With a crack model, the further growth of interface crack is analyzed, and some important experimental phenomena can be predicted. The failure mechanism which the particle will be punched into matrix has been also discussed. The critical differences between the creep properties of the particles and matrix have been calculated, after a parameter has b

关键词： Indentation creep test Particle-reinforced composites computer simulation Deformation Failure

computer simulation of interface evolution for an Al-Li alloy during early aging stage

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2004年第3期23卷 279-285页

作者： TANGLiying WANGYongxin CHENZheng LUYanli ZHANGJianjun DepartmentofMaterialsScienceandEngineering NorthwesternPolytechnicalUniversityXi＇an710072China DepartmentofMaterialsScienceandEngineering NorthwesternPolytechnicalUniversityXi＇an710072China

The nucleation of ordered phase was simulated based on microscopic diffusionequation and the assumptions of the classical nucleation theory were examined. The quantitativecalculations of interface thickness evolution were accomplished for the first time. It was foundthat the interfaces between ordered phase and disordered matrix were diffuse. The interfacethickness decreased with time, from the initial 1.2 nm to an equilibrium value 0.6 nm. The ratios ofthe radius of ordered particles and the interface thickness monotonously increased, but they wereof the same order of magnitude all the time. The sharp interface assumption should not be adopted inthis stage. For the Al-10% Li (atom fraction) alloy aged at 192℃, the assumptions of the classicalnucleation theory disagreed with the facts. The phase transformation followed the non-classicalnucleation mechanism and the applicable scope of the classical nucleation should be confined.

关键词： metal material interface computer simulation non-classical nucleationtheory

computer simulation OF CONTINUOUS ELECTROMAGNETIC STIRRING FOR MAKING RHEOLOGIC SEMI-SOLID SLURRY OF ZL112Y ALUMINUM ALLOY

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2008年第6期21卷 108-114页

作者： LIU Changming YANG Ling ZUO Hongzhi College of Material Science and Engineering Chongqing University Chongqing 400044 China

To realize the technology of fabricating the rheologic semi-solid slurry of ZL112Y aluminum alloy via continues electromagnetic stirring process, ANSYS software was used to simulate electromagnetic force field and fluid velocity field in the alloy melt in a crucible tube in three coils. In the first section of the paper, eletromagnetic force field and fluid velocity field caused by single coil were simulated. The result of this simulation gives an average velocity of 3.2 cm/s and it is called critical velocity because a fluid velocity over it will cause a fine and spherical structure of solid primary a in a semi-solid melt. And, from this result, a reasonable temperature of semi-solid of the alloy and an electrical current intensity were established. The electrical current intensity of the result of this simulation corresponded to the current intensity used in a practice experiment, in which the primary α was obviously refined and sphericized. Based on this simulation of single coil electromagnetic stirring, in the second section of the paper, eletromagnetic force field and fluid velocity field caused by three coils were simulated. The result of the simulation shows that, 1） there is a semi-solid zone of 32 mm from bottom of the crucible tube to the upper; 2） the electrical current intensities of three coils of 400 A, 600 A, and 400 A, which were set to top range, middle range and bottom range of the tube, respectively, were the optimum parameters of electromagnetic current intensity under the condition of this investigation; and 3） under effect of these electromagnetic current intensity, the fluid velocities of the melt in the tube were 6.3 cm/s in top range, 3.75 cm/s in middle range, and 3.9 cm/s in bottom range of it, respectively.

关键词： Electromagnetic stirring Electromagnetic force field Fluid velocity field Rheologic semi-solid slurry computer simulation

computer simulation on the controlled cooling of 82B high-speed rod

在线全文

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2008年第3期15卷 330-334页

作者： Jinqiao Xu Yazheng Liu Shumei Zhou School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

A modified temperature-phase transformation field coupled nonlinear mathematical model was made and used in computer simulation on the controlled cooling of 82B high-speed rods. The surface temperature history and volume fraction of pearlite as well as the phase transformation history were simulated by using the finite element software Marc/Mentat. The simulated results were compared with the actual measurement and the agreement is good which can validate the presented computational models.

关键词： high-speed steel controlled cooling phase transformation computer simulation

computer simulation of Ferrite Transformation during Hot Working of Low Carbon Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2004年第5期20卷 497-500页

作者： Yunbo XU, Yongmei YU, Xianghua LIU and Guodong WANGState Key Laboratory of Rolling and Automation, Northeastern University, P.O. Box 105, Shenyang 110004, China Lab. of Rolling and Automat. Northeastern Univ. Shenyang 110004 P.O. Box 105 China

On the basis of transformation kinetics and thermodynamics, the austenite-ferrite transformation start temperature during deformation was predicted for several grades of low-carbon steels under different processing conditions. Results indicate that Ar3d temperature mostly depended on alloying composition and processing parameters. Ar3d increased as strain rate or strain increased for the same steel grade. In view of enhancement of deformation on transformation, the basic kinetics model was established to simulate deformation induced transformation behavior, using which the influence of the deformation stored energy and effective deformation ledge on the nucleation and growth can be considered. The simulated results are in good agreement with experiment results.

关键词： computer simulation Transformation kinetics Ultrafine ferrite Deformation induced transformation

computer simulation OF CREEP DAMAGE AT CRACK TIP IN SHORT FIBRE COMPOSITES

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1994年第3期10卷 282-288页

作者：张双寅蔡良武 Institute of Mechanics Chinese Academy of SciencesBeijing 100080China

Creep damage at crack tip in short fibre composites has been sim- ulated by using the finite element method(FEM).The well-known Schapery non- linear viscoelastic constitutive relationship was used to characterize time-dependent behaviour of the material.A modified recurrence equation was adopted to accelerate the ***-Rabotnov's damage evolution law was *** growth of the damage zone with time around the crack tip was calculated and the results were shown with the so-called 'digit photo',which was produced by the printer.

关键词： creep damage visco-elasticity finite element method short fibre composite computer simulation

computer simulation of Microstructure Evolution of 82B Rod at Different Cooling Rates

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2008年第2期15卷 56-59,64页

作者： XU Jin-qiao LIU Ya-zheng ZHOU Shu-mei Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

According to thermodynamics and kinetics of phase transformation,a mathematical model of phase transformation was proposed,and the microstructure evolution of an 82B rod at different cooling rates was simulated by using the FEM software Marc/Mentat,based on the measurement of time-temperature transformation（TTT）curves of the 82B *** simulated results were in good agreement with the actual *** the results of computer simulation it was found that the cooling rate of the 82B rod,after laying,should be controlled within 5-8 ℃/*** the microstructure of rod there were over 95% of pearlite volume fraction and a small quantity of dispersive martensite（less than 5%）.

关键词： computer simulation microstructure evolution controlled cooling 82B rod

computer simulation of Insoluble Pr(III) Speciation in Human Interstitial Fluid

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2002年第7期13卷 658-659页

作者： HaiYuanZHANG XingLU 等 KeyLaboratoryofRareEarthChemistryandPhysics ChangchunInstituteofAppliedChemistryChineseAcademyofSciencesChangchun130022 KeyLaboratoryofRareEarthChemistryandPhysics ChangchunInstituteofAppliedChemist

A multi-phase model of Pr(III) speciation in human interstitial fluid was constructed and insoluble Pr(III) speciation was studied. When the total concentration of Pr(III) is below 8.401E-10 mol/L, soluble Pr(III) species are main species. With rising the total concentration of Pr(III), Pr(III) is firstly bound to phosphate to form precipitate of PrPO4, then bound to carbonate and another precipitate of Pr2(CO3)3 was obtained. When the total concentration is between 1.583E-9 mol/L and 4.000E-3 mol/L, the insoluble species are predominant Pr(III) species.

关键词： computer simulation praseodymium(III) speciation human interstitial fluid.

computer simulation of Gd(III) Speciation in Human Interstitial Fluid

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2003年第2期14卷 217-218页

作者： Jin Ping WANG Hai Yuan ZHANG 等 KeyLaboratoryofRareEarthChemistryandPhysics ChangchunInstituteofAppliedChemistryChineseAcademyofSciencesChangchun130022 KeyLaboratoryofRareEarthChemistryandPhysics ChangchunI

The speciation and distribution of Gd(III) in human interstitial fluid was studied by computer simulation. Meantime artificial neural network was applied to the estimation of log ?values of complexes. The results show that the precipitate species, GdPO4 and Gd2(CO3)3, are the predominant species. Among soluble species, the free Gd(III), [Gd(HSA)] , [Gd(Ox)] and then the ternary complexes of Gd(III) with citrate are main species and [Gd3(OH)4] becomes the predominant species at the Gd(III) total concentration of 2.2?0-2mol/L.

关键词： computer simulation gadolinium(III) speciation human interstitial fluid.