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Simulations of deformation and damage processes of SiCp/Al composites during tension

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Journal of Materials Science & Technology 2018年第4期34卷 627-634页

作者： J.f.zhang X.X.zhang Q.z.wang B.L.Xiao z.y.Ma Sheny.ng national Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China

The deformation, damage and failure behaviors of 17 vol.% SiCp/2009Ai composite were studied by micro- scopic finite element （fE） models based on a representative volume element （RVE） and a unit cell. The RVE having a 3D realistic microstructure was constructed via computational modeling technique, in which an interface phase with an average thickness of 50 nm was generated for assessing the effects of interracial properties. Modeling results showed that the RVE based fE model was more accurate than the unit cell based one. Based on the RVE, the predicted stress-strain curve and the fracture morphology agreed well with the experimental results. furthermore, lower interface strength resulted in lower flow stress and ductile damage of interface phase, thereby leading to decreased elongation. it was revealed that the stress concentration factor of SiC was -2.0： the average stress in SiC particles reached -1200 MPa, while that of the composite reached -600 MPa.

关键词： Metal matrix composites (MMCs) fracture finite element (fE) analysis interfacial strength Tensile strength Representative volume element (RVE)

Anisotropic Electroplastic Effects on the Mechanical Properties of a nano-Lamellar Austenitic Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2021年第4期34卷 534-542页

作者： y.R.Ma H.J.y.ng D.D.Ben X.H.Shao y.z.Tian Q.Wang z.f.zhang Shi-changxu innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Sciences and Technology of ChinaHefei230026China Sheny.ng national Laboratory of Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang110016China

Effects of electropulsing treatment(EPT)on the microstructural evolution and mechanical properties of a cold-rolled 316 L austenitic stainless steel with nano-lamellar structure were *** EPT experiments were carried out with the electric current direction along the rolling direction(RD)and the transverse direction(TD)of the samples,*** anisotropic electroplastic effects for the RD and TD specimens,i.e.,reduced hardness/strength and enhanced ductility,were obtained owing to the different recrystallization behaviors of the RD and TD specimens during *** RD specimens after EPT with larger recrystallized grain size and higher volume fraction of recrystallization show lower strength and higher elongation than that of the TD *** main reason might be attributed to the change of the current direction in the two kinds of samples,which results in the different sensitivity of the microstructures to thermal and athermal effects during EPT.

关键词： Stainless steel Electroplastic effect Electropulsing Recrystallization Anisotropy Strength Plasticity

numerical Solutions for Heat Transfer of An Unsteady Cavity with Viscous Heating

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Computers, Materials & Continua 2021年第7期68卷 319-336页

作者： H.f.Wong Muhammad Sohail z.Siri n.f.M.noor institute of Mathematical Sciences Faculty of ScienceUniversity of Malaya50603 Kuala LumpurMalaysia Unit of Engineering Design and Product Development Technology and Engineering DivisionMalaysian Rubber Board47000 Sungai BulohMalaysia Department of Applied Mathematics&Statistics Institute of Space Technology44000 IslamabadPakistan

The mechanism of viscous heating of a newtonian fluid filled inside a cavity under the effect of an external applied force on the top lid is evaluated numerically in this *** investigation is carried out by assuming a two-dimensional laminar in-compressible fluid flow subject to neumann boundary conditions throughout the numerical iterations in a transient *** the walls of the square cavity are perfectly insulated and the top moving lid produces a constant finite heat flux even though the fluid flow attains the steady-state *** objective is to examine the effects of viscous heating in the fully insulated lid-driven cavity under no-slip and free-slip neumann boundary conditions coupled with variations in Reynolds and Prandtl *** partial differential equations of time-dependent vorticity-stream function and thermal energy are discretized and solved using a self-developed finite difference code in MATLAB®*** dependence of fluid thermodynamics is envisaged through contour and image plots.A commercial simulation software,Ansys fluent®utilizing a finite element code is employed to verify the finite difference results *** the effect of viscous heating is very minimal,neumann no-slip and free-slip boundary conditions are able to trap the heat inside the fully insulated cavity as the heat flux is constantly supplied at the top lid.A lower Reynolds number and a greater Prandtl number with free-slip effects reduce temperature distribution in the cavity with a faster velocity than in the no-slip condition as the free-slip behaves as a lubricant.

关键词： Lid-driven viscous heating vorticity-stream function finite difference method finite element method

Universality of quenching-partitioning-tempering local equilibrium model

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Journal of Materials Science & Technology 2022年第29期124卷 116-120页

作者： J.z.zhang L.y.zeng X.W.zuo J.f.Wan y.H.Rong n.Min J.Lu n.L.Chen Department of Mechanical Engineering City University of Hong KongGreater Bay Joint DivisionShenyang National Laboratory for Materials ScienceTat Chee AvenueKowloonHong KongChina Shanghai Key Laboratory of Materials Laser Processing and Modification School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Laboratory for Microstructures Shanghai UniversityShanghai 201900China CityU-Shenzhen futian Research institute Shenzhen 518045China

*** As typical 3rd generation advanced high strength steels(AHSSs),quenching and partitioning(Q&P)steel has attracted lots of attention for excellent performance in strength-ductility[1–5].With absorbing carbon partitioning as the core idea of Q&P process,quenching-partitioning-tempering(Q-P-T)process was proposed with emphasis on precipitation strengthening for better combination of strength and ductility[6–10].

关键词： tempering strength ductility

Variational Corner Transfer Matrix Renormalization Group Method for Classical Statistical Models

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Chinese Physics Letters 2022年第6期39卷 65-70页

作者： X.f.Liu y.f.fu W.Q.yu J.f.yu z.y.Xie Department of Physics Renmin University of ChinaBeijing 100872China School of Physics and Electronics Hunan UniversityChangsha 410082China

in the context of tensor network states,we for the first time reformulate the corner transfer matrix renormalization group(CTMRG)method into a variational bilevel optimization *** solution of the optimization problem corresponds to the fixed-point environment pursued in the conventional CTMRG method,from which the partition function of a classical statistical model,represented by an infinite tensor network,can be efficiently *** validity of this variational idea is demonstrated by the high-precision calculation of the residual entropy of the dimer model,and is further verified by investigating several typical phase transitions in classical spin models,where the obtained critical points and critical exponents all agree with the best known results in *** extension to three-dimensional tensor networks or quantum lattice models is straightforward,as also discussed briefly.

关键词： tensor variational straight

Aerodynamic shape optimization of an urban maglev train

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Acta Mechanica Sinica 2021年第6期37卷 954-969,I0002页

作者： z.X.Sun M.y.Wang L.y.Wei f.B.Kong G.W.y.ng Key Laboratory for Mechanics in fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing101408China CRRC Tangshan Co. Ltd TangshanHebei063000China

With rapid development of urban rail transit,maglev trains,benefiting from its comfortable,energy-saving and environmentally friendly merits,have gradually entered people's *** this paper,aiming at improving the aerodynamic performance of an urban maglev train,the aerodynamic optimization design has been *** improved two-point infill criterion has been adopted to construct the cross-validated Kriging ***,the multi-objective genetic algorithm and complex three-dimensional geometric parametrization method have been used,to optimize the streamlined head of the *** optimal shapes have been *** reveal that the optimization strategy used in this paper is sufficiently accurate and time-efficient for the optimization of the urban maglev train,and can be applied in practical *** to the prototype of the train,optimal shape benefits from higher lift of the leading car and smaller drag of the whole *** analysis reveals that the length and height of the streamlined head have a great influence on the aerodynamic performance of the train,and strong nonlinear relationships exist between these design variables and aerodynamic *** conclusions drawn in this study offer the chance to derive critical reference values for the optimization of the aerodynamic characteristics of urban maglev trains.

关键词： Urban maglev train Aerodynamic characteristics Cross validation Kriging model Genetic algorithm

Mechanisms of eutectic lamellar destabilization upon rapid solidification of an undercooled Ag-39.9 at.% Cu eutectic alloy

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Journal of Materials Science & Technology 2020年第24期59卷 173-179页

作者： H.Dong y.z.Chen z.R.zhang G.B.Shan W.X.zhang f.Liu State Key Lab.of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China y.ngtze River Delta Research institute of nPU Taicang 215400China

The eutectic Ag-Cu alloys exhibiting fine Ag-Cu lamellar eutectic structure formed upon rapid solidification have great potentials being used in various engineering ***,the desired fine primary lamellar eutectic structure(PLES)is usually replaced by a coarse anomalous eutectic structure(AES)when the undercooling prior to solidification exceeds a certain *** forming mechanism of AES in the undercooled eutectic Ag-Cu alloy has been a controversial *** this work,the undercooled Ag-39.9 at.% Cu eutectic alloy is solidified under different cooling conditions by using techniques of melt fluxing and copper mold *** results show that the coupled eutectic growth of this alloy undergoes a transition from a slow eutectic-cellular growth(ECG)to a rapid eutectic-dendritic growth(EDG)above a undercooling of 72 K,accompany.ng with an abrupt change of the distribution and amount of AES in as-solidified *** kinds of primary lamellar eutectic structures are formed by ECG and EDG during recalescence,*** destabilization of PLES that causes the formation of AES is ascribed to two different mechanisms based on the microstructural examination and theoretical *** 72 K,the destabilization of PLES formed by slow ECG is caused by the mechanism of"termination migration"driven by interfacial *** above 72 K,the destabilization of PLES formed by rapid EDG is attributed to the unstable perturbation of interface driven by interfacial energy and solute supersaturation.

关键词： Ag-Cu alloys Rapid solidification Undercooling Eutectics Destabilization

Linking discrete particle simulation to continuum process modelling for granular matter: Theory and application

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Particuology 2011年第4期9卷 342-357页

作者： H.P. zhu z.y. zhou Q.f. Hou A.B. yu School of Engineering University of Western Sydney Locked Bag 1797 Penrith NSW 2751 Australia Laboratory for Simulation and Mo-delling of Particulate Systems School of Materials Science and Engineering The University of New South Wales Sydney NSW 2052 Australia

Two approaches are widely used to describe particle systems： the continuum approach at macroscopic scale and the discrete approach at particle scale. Each has its own advantages and disadvantages in the modelling of particle systems. it is of paramount significance to develop a theory to overcome the disadvantages of the two approaches. Averaging method to link the discrete to continuum approach is a potential technique to develop such a theory. This paper introduces an averaging method, including the theory and its application to the particle flow in a hopper and the particle-fluid flow in an ironmaking blast furnace.

关键词： Particle flow Gas-solid flow Discrete approach Averaging method Hopper flow Blast furnace

Coercivity Enhancement of nd-fe-B Thin film Magnets through Dy Surface Diffusion Process

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Journal of Materials Science & Technology 2011年第9期27卷 826-830页

作者： C.y. you J. zhu n. Tian z.X. Lu State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Xi＇an University of Technology Xi＇an 710048 China

The Dy capping layer was deposited at different temperatures on the nd-fe-B thin films to investigate the mechanism of the coercivity enhancement through the Dy surface diffusion. The highest coercivity of 2005 kA/m （25.2 kOe） was obtained at the Dy deposition temperature of 460℃, which was significantly higher than the value of 1297 kA/m （16.3 kOe） without Dy capping layer. By performing the transmission electron microscopy （TEM） analysis, it was found that some of the grain boundaries were enriched with nd element, which could be partly ascribed to the promotion by the Dy surface diffusion. in comparison to the evolution of the spin reorientation temperature of nd2fe14B phase after the deposition of the Dy capping layer, it is concluded that structural modification plays a significant role in the coercivity enhancement due to the Dy surface diffusion.

关键词： nd-fe-B thin film Coercivity enhancement Dy layer Microstructure