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Tectonic framework of China and its relation with mineral resources——Cognition from geophysical data

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Chinese Science Bulletin 1997年第2期42卷 89-95页

作者： liu, GD Hao, Ty liu, y Institute of Geophysics Chinese Academy of Sciences Beijing 100101 China

TECTONIC and its evolution are theoretical basis of geology and summation in geosciences from investigation of the earth’s structure, composition, motion and history. Therefore, they are of great importance to the industrial activities. Various geological maps have been compiled in different scales after long-time observation of rock outcrops in mountains and torrents. These tectonic maps, which are obtained based upon the cognition and judgment of tectonic movements in different ages, are summarization regarding the regularity of geological phenomenon in terms of theory, and provide service of exploration and references for environmental protection and prevention and control of disaster.

关键词： tectonic geophysics macroscopic framework.

Alloy solidification: Assessment and improvement of an easy-to-apply model

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Journal of Materials Science & Technology 2022年第35期130卷 1-11页

作者： H.liu y.liu S.L.Lu y.Zhang H.Chen y.Chen M.Qian School of Materials Science and Engineering Southwest Jiaotong UniversityChengdu 610031China Centre for Additive Manufacturing School of EngineeringRMIT UniversityMelbourneVIC 3000Australia School of Materials Science and Engineering Sichuan UniversityChengdu 610065China

It has been a central task of solidification research to predict solute microsegregation. Apart from the Lever rule and the Scheil-Gulliver equation, which concern two extreme cases, a long list of microsegregation models has been proposed. However, the use of these models often requires essential experimental input information, e.g., the secondary dendrite arm spacing(λ), cooling rate( ˙T) or actual solidification range(△T). This requirement disables these models for alloy solidification with no measured values for λ,˙T and △T. Furthermore, not all of these required experimental data are easily obtainable. It is therefore highly desirable to have an easy-to-apply predictive model that is independent of experimental input,akin to the Lever rule or Scheil-Gulliver model. Gong, Chen, and co-workers have recently proposed such a model, referred to as the Gong-Chen model, by averaging the solid fractions(f_(s)) of the Lever rule and Scheil-Gulliver model as the actual solid fraction. We provide a systematic assessment of this model versus established solidification microsegregation models and address a latent deficiency of the model, i.e.,it allows the Lever rule solid fraction fsto be greater than one(f_(s)> 1). It is shown that the Gong-Chen model can serve as a generic model for alloy solidification until fsreaches about 0.9, beyond which(f_(s)> 0.9) its applicability is dictated by both the equilibrium solute partition coefcient(k) and the solute diffusion coefcient in the solid(Ds), which has been tabulated in detail.

关键词： Solidification Microsegregation Solute Back diffusion Eutectic formation

Natural vibration of cantilever porous twisted plate with variable thickness in different directions

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Defence Technology(防务技术) 2023年第9期27卷 200-216页

作者： y.X.Hao y.y.liu W.Zhang L.T.liu K.C.Sun S.W.yang College of Mechanical Engineering Beijing Information Science and Technology UniversityBeijing100192PR China College of Mechanical Engineering Beijing University of TechnologyBeijing100124PR China

In this paper,the blade is assumed to be a rotating variable thickness cantilever twisted plate structure,and the natural vibrations of variable thickness cantilever twisted plate made of metal porous material are *** is assumed that the thickness of the plate changes along spanwise direction and chordwise direction,respectively,and it changes in both *** classical thin shell theory,the first and second fundamental forms of surface and von Karman geometric relationship are employed to derive the total potential energy and kinetic energy of the cantilever twisted plate,in which the centrifugal force potential due to high rotational speed is ***,according to the Rayleigh-Ritz procedure and applying the polynomial functions which satisfy the cantilever boundary conditions,the dynamic system expressed by equations of motion is reduced to an eigenvalue *** numerical simulation,the frequency curves and the mode shapes of the twisted plate can be obtained to reveal the internal connection between natural vibration and the parameters.A series of comparison studies are performed to verify the accuracy of the present formulation and calculations,in which compared data come from experimental,finite element method and theoretical calculation,*** influence of pre-twist angle,three different forms of thickness taper ratio and rotational speed on natural vibration,mode exchange and frequency veering phenomenon of the system is discussed in *** addition,the approach proposed here can efficiently extract analytical expressions of mode functions for rotating variable thickness cantilever twisted plate structures.

关键词： Porous cantilever twisted plate Variable thickness Natural vibration Frequency veering Mode exchange

Investigation on the Microstructure Homogenization in a TiAl Based Alloy Prepared by Elemental Powder Metallurgy

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Journal of Materials Science & Technology 1999年第6期15卷 527-530页

作者： liu, y Huang, By He, yH Wang, JN Cent S Univ Natl Key Lab Powder Met Changsha 410083 Hunan Peoples R China

A Ti-48Al (at. pet) alloy prepared by elemental powder metallurgy (EPM) has been heat treated under various conditions. Through optical and scanning electronic microscopy, EDAX, XRD analysis, and DTA, it was shown that the hot pressed microstructure consisted of alpha(2)-Ti3Al and TiAl phases. The alpha(2)-Ti3Al phase was island-like, and had a high stability and heredity in subsequent heat treatments. The supersaturation of Al in the island-like alpha-Ti3Al phase strongly influenced the transformation of alpha(or alpha(2)) to alpha(2)/gamma lamellar colonies. After a heat treatment at 1380 degrees C for 0.5 h and 1000 degrees C for 8 h, a fully lamellar microstructure with a colony size of 50 mu m was obtained. This result indicates that a homogeneous composition and an equilibrium microstructure in EPM TiAl-base alloys can only be obtained after heat treatment at temperatures above alpha transus temperature (T-alpha).

关键词： Titanium alloys

Partition method and experimental validation for impact dynamics of flexible multibody system

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Acta Mechanica Sinica 2018年第3期34卷 482-492页

作者： J.y.Wang Z.y.liu J.Z.Hong School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University

The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one of the main difficulties in many engineering applications. The numerical approaches being used widely in impact analysis are mainly from two fields： multibody system dynamics （MBS） and computational solid mechanics （CSM）. Approaches based on MBS provide a more efficient yet less accurate analysis of the contact/impact problems, while approaches based on CSM are well suited for particularly high accuracy needs, yet require very high computational effort. To bridge the gap between accuracy and efficiency in the dynamic simulation of a flexible multibody system with contacts/impacts, a partition method is presented considering that the contact body is divided into two parts, an impact region and a non-impact region. The impact region is modeled using the finite element method to guarantee the local accuracy, while the non-impact region is modeled using the modal reduction approach to raise the global efficiency. A three-dimensional rod-plate impact experiment is designed and performed to validate the numerical results. The principle for how to partition the contact bodies is proposed： the maximum radius of the impact region can be estimated by an analytical method, and the modal truncation orders of the non-impact region can be estimated by the highest frequency of the signal measured. The simulation results using the presented method are in good agreement with the experimental results. It shows that this method is an effec-rive formulation considering both accuracy and efficiency. Moreover, a more complicated multibody impact problem of a crank slider mechanism is investigated to strengthen this conclusion.

关键词： Partition method Impact dynamics Experimental investigation Efficiency and accuracy Partition principle

REACTIONS OF C_(60) WITH R_3SnH: A NEW SyNTHETIC TO C_(60)(RH)n AND THE PROPERTy OF C_(60) TO CATALyZE RADICAL REACTIONS

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Chinese Chemical Letters 1996年第5期7卷 433-436页

作者： She y.M. Tu y.P. Guo X.H. liu Z.y. liu S.y. Changchun Inst. of Applied Chemistry Chinese Academy of Sciences Changchun 130022

Abstract: A new method for the preparation of polyakyl and polyarenefullerene derivatives C60(RH)n (R=Bu,n=1-3; R=Ph,n=1-10) by the reaction of C60 with organotin hydride in toluene is described. Another series of products of stannanes RaSnbHc (B=Ru, a=3-8, b=1-4, c=0-3; R=Ph.a=3-11, b=1-5, e=0-4) were also obtained which shows that C60 can catalyze polymerization of organic-tin. These products were detenrmined by mass and infrared spectromeny. And the possible reaction mechanisms are discussed.

关键词： CHEMISTRy C60 FULLERENES

Numerical Simulation of Welding Deformation for Hull Superstructure Steel Based on the Finite Element Analysis

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Journal of Materials Science & Technology 2003年第Z1期19卷 212-214页

作者： liu L. Liang G. liu y. Zhan Z. Dalian Univ. of Technol. Dalian 116024 China Lab. of Adv. Welding Technol. Harbin Inst. of Technol. Harbin 150001 China Dalian Dockyard Dalian 116020 China

Using finite analysis element software, the transient displacement field of automatic submerged arc welding is established. It was also considered that the thermal physical properties changes were depended on the temperatureand the heat loss on the surface. At the same time, it analyzed the influence of the deformation and stress, whichgenerated in the plate butt-welding process, to the superstructure steel welding deformation. The result showedthat the deformation and stress generated in the steel plate butt-welding process are considered to be the mainfactors to influence the welding deformation of superstructure steel. It found the effective ways to reduce the weldingdeformation of the hull superstructure steel is to relieve the butt-welding deformation and release butt-welding stressbefore welding the hull superstructure steel.

关键词： Hull superstructure steel, Finite element analysis, Welding deformation

Finite Element Prediction of the Thermal Conductivity of GNP/Al Composites

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Acta Metallurgica Sinica(English Letters) 2022年第5期35卷 825-838页

作者： X.S.yang L.Zhou K.y.liu Z.y.liu Q.Z.Wang B.L.Xiao Z.y.Ma School of Electromechanical and Automotive Engineering Yantai UniversityYantai264005China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

A 3 D multi-scale finite element model was developed to predict the effective thermal conductivity of graphene nanoplatelet(GNP)/Al *** factors influencing the effective thermal conductivity of the GNP/Al composites were investigated,including the orientation,shape,aspect ratio,configuration and volume fraction of *** results show that GNPs shape has a little influence on the thermal conductivity of GNP/Al composites,and composites with elliptic GNPs have the highest thermal *** addition,with increasing the aspect ratio of GNPs,the thermal conductivity of GNP/Al composites increases and finally tends to be *** GNPs configuration strongly influences the thermal conductivity of GNP/Al composites,and the thermal conductivity of the composites with layered GNPs is the highest among the five *** effective thermal conductivity is sensitive to volume fraction of ***,when the volume fraction of layered GNPs reaches 1.54%,the thermal conductivity of GNP/Al composites is as high as 400 W/m *** findings of this study could provide a good theoretical basis for designing high thermal conductivity GNP/Al composites.

关键词： Multi-scale finite element model Thermal conductivity GNP/Al composites Shape Aspect ratio Configuration

Effect of Heat Treatment Time on Dy–Cu Alloy Diffusion Process in Dy-Containing Commercial Nd–Fe–B Sintered Magnets

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Acta Metallurgica Sinica(English Letters) 2018年第5期31卷 496-502页

作者： H.y.liu G.Wang y.Hong D.C.Zeng School of Materials Science and Engineering South China University of Technology

In this paper, the grain boundary diffusion process（GBDP） using a Dy70Cu30（at.%） alloy as the diffusion source was performed in a commercial sintered Nd–Fe–B magnet, and the effect of heat treatment time on the microstructure and magnetic properties of the magnet was investigated in detail. For the processed magnets heat-treated at 860℃, as heat treatment time increased, the coercivity and the depth of（Nd,Dy）2Fe14B core–shell structure increased first and then decreased. However, when the heat treatment time was more than 2 h, the diffusion path of Dy from the Dy-rich shell phase into the Nd2Fe14B grains was revealed, and a nearly homogeneous（Nd,Dy）2Fe14B phase was formed, which brought on the decrease in both the depth of visible core–shell structure and the coercivity of Nd–Fe–B magnet.

关键词： Sintered Nd-Fe-B magnets Grain boundary diffusion Heat treatment time Coercivity Micromagnetic simulation