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Effects of the Reversely Rotating Assisted Shoulder on Microstructures During the Reverse Dual-rotation Friction Stir Welding

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Journal of Materials Science & Technology 2015年第4期31卷 375-383页

作者： J.q.Li h.J.Liu State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Capital Aerospace Machinery Company

The reverse dual-rotation friction stir welding(RDR-FSW) has the capability to adjust the heat generation because of the separately designed tool shoulder and tool *** welding torque exerted on the workpiece by the reversely rotating shoulder is opposite to that exerted by the rotating tool pin,so the total welding torque is reduced,which is beneficial to reducing the clamping requirement of *** the present paper,a RDR-FSW joint was welded in a condition similar to the optimal welding condition of conventional FSW,and microstructures in various zones were investigated by comparison,aiming to highlight effects of the reversely rotating assisted *** to the heat conduction of the middle cylinder and the bottom end cover on which the assisted shoulder was machined,the thermal effect of RDR-FSW was smaller than that of the conventional ***,the effect of assisted shoulder on the plastic flow or deformation of material or was constrained in a thin layer near the weld top surface,and thus the flow of material especially along the thickness direction was clearly decreased in the *** the heat-affected zone(hAZ),the precipitate coarsening was the main evolution and was completed through the dissolution of small precipitates and the continuous growth of large *** contrast,the dissolution degree of precipitates increased significantly in the thermomechanically affected zone(TMAZ),and a small amount of original meta-stable precipitates transformed to block-shaped stable *** evolutions in the shoulder affected zone(SAZ)and the weld nugget zone were similar,*** majority of original meta-stable precipitates dissolved into the matrix and the remainder transformed to stable precipitates,though the dissolution degree was greater in the *** with the conventional FSW joint,the coarsening degrees of precipitates in the hAZ and TMAZ of RDR-FSW joint were much smaller,as well as the dissolution degrees of p

关键词： Friction stir welding Reverse dual-rotation fricti

PARTICLE SIZE AND MICROSTRUCTURE OF Ni NANOPOWDERS PREPARED BY ANODIC ARC PLASMA

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 209-216页

作者： Z.q.Wei h.X.qiao J.F.Dai W.J.Feng q.wang P.X.Yan SchoolofSciences LanzhouUniversityofTechnologyLanzhou730050China CollegeofCivilEngineering LanzhouUniversityofTechnologyLanzhou730050China SchoolofPhysicalScienceandTechnology LanzhouUniversityLanzhou730000China

Pure Ni nanopowders were successfully prepared by the method of anodic arc disch arged plasma with homemade experimental apparatus. The particle size, mircostruc ture and morphology of the particles by this process were characterized via X-ra y powder diffraction (XRD), transmission electron microscopy (TEM) and the corre sponding selected area electron diffraction (SAED); The specific surface area an d pore parameters were investigated by multi-point full analysis of nitrogen ads orption-desorption isotherms at 77K by Brunauer- Emmett-Teller (BET) surface are a analyzer; The chemical composition were determined by X-ray energy dispersive spectrometry (XEDS) equipped in SEM and element analyze instrument. The experime nt results indicate that the samples by this method with high purity,the crystal structure of the particles is as same as the bulk material, is fcc structure, w ith average particle sizes about 47nm, ranging from 20 to 70nm, and distributed uniformly in spherical chain shapes, the specific surface areavis 14.23m2/g, po re volume of pore is 0.09cm3/g and average pore diameter is 23nm.

关键词： anodic arc plasma Ni nanopowder particle size structure composition.

hYBRID LINEAR AND qUADRATIC FINITE ELEMENT MODELS FOR 3D hELMhOLTZ PROBLEMS

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Acta Mechanica Solida Sinica 2013年第6期26卷 603-618页

作者： q.h.Zhang K.Y.Sze Guangdong Province Key Laboratory of Computational Science Sun Yat-Sen University Department of Mechanical Engineering The University of Hong KongPokfulam

In this paper, linear and quadratic finite element models are devised for the three- dimensional helmholtz problem by using a hybrid variational functional. In each element, contin- uous and discontinuous helmholtz fields are defined with their equality enforced over the element boundary in a weak sense. The continuous field is based on the C° nodal interpolation and the discontinuous field can be condensed before assemblage. hence, the element can readily be in- corporated seamlessly into the standard finite element program framework. Discontinuous fields constructed by the plane-wave, Bessel and singular spherical-wave solutions are attempted. Nu- merical tests demonstrate that some of the element models are consistently and considerably more accurate than their conventional counterparts.

关键词： finite element hybrid helmholtz Bessel plane-wave spherical-wave radial basis function

STUDY ON ThE ShOCK WAVE CRYSTALLIZATION OF AMORPhOUS ALLOYS BY DSC

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Acta Metallurgica Sinica(English Letters) 2002年第5期15卷 431-438页

作者： h. Y. Zhao, h. wang, q.J. Liu, J.D. Kan and Z.q. LiuDepartment of Materials Science and Engineering, Yunnan University, Kunming 650091, China Department of Materials Science and Engineering Yunnan University

Shock wave and annealing crystallization of amorphous alloys FeSiB, FeMoSiB and FeCuNbSiB were studied by isothermal and non-isothermal DSC technique. It was found that the shock wave crystallization is very perfect, the fraction crystallized is very close to 100%, though the period of crystallization is very short, only about 10-4-10-6s. Their produced phases differ from the parent phase in structure and composition. The high velocity of the transformation is very difficult to explain by the diffusion theory of solid state phase transition.

关键词： amorphous alloy nano-crystallization shock wave crystalliza-tion

Effect of water injection on the cavitation control:experiments on a NACA66(MOD)hydrofoil

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Acta Mechanica Sinica 2020年第5期36卷 999-1017,I0001页

作者： W.wang T.Tang q.D.Zhang X.F.wang Z.Y.An T.h.Tong Z.J.Li School of Energy and Power Engineering Dalian University of TechnologyDalian 116024China Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of EducationDalian University of TechnologyDalian 116024China

The objective of this work is to investigate experimentally controlling cavitating flow over NACA66(MOD)hydrofoils by means of an active water injection along its suction *** continuous water vertically jets out of the chamber inside the hydrofoil through evenly distributed surface *** were carried out in cavitation water *** high-speed visualization technology and the particle image velocimetry(PIV)system to study the sheetlcloud cavity *** studied the effects of this active control on cavity evolution with four kinds of jet flow at two different jet *** analyzed the effect of water injection on the mechanism of the cavitating flow *** results were all compared with that for the original hydrofoil without jet and show that the active jet can effectively suppress the sheet/cloud cavitation characterized by shrinking the attached cavity size and breaking the large-scaled cloud sheding vortex cavity into small-scaled *** optimum effectiveness of cavitation suppression is affected by the jet flow rates and jet *** water injection at flow rate coefficient 0.0245 with the jet position of 0.45C reduces the maximum sheet cavity length by 79.4%and the cavity shedding is diminished completely,which gives the most superior effect of sheet cavitation *** jet blocks the re-entrant jet moving upstream and weakens the power of re-entrant jet and thus restrains the cavitation development effectively and stabilizes the flow field.

关键词： Cavitation active control Sheet/cloud cavitation.Water injection Re-entrant jet

Stability and optoelectronic property of low-dimensional organic tin bromide perovskites

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Chinese Physics B 2021年第3期30卷 483-487页

作者： J h Lei q Tang J he M q Cai School of Science Hunan University of TechnologyZhuzhou 412007China School of Physics and Electronics Science Hunan UniversityChangsha 410082China

The toxicity and degradation of hybrid lead-halide perovskites hinder their extensive *** is thus of great importance to explore non-toxic alternative materials with excellent stability and optoelectronic *** investigate the atomic structures and optoelectronic properties of non-toxic organic tin bromide perovskites(OTBP)with one/zerodimensional(1D/0D)structures by first-principles *** calculated atomic structures show that the 1D/0D OTBPs are stable and the structure of inorganic octahedra in 0D is higher order than that in ***,the origination of exceptional purity emitting light in experiments is explained based on the calculated electronic structure.

关键词： one/zero dimensional non-toxic organic tin bromide perovskites first principle calculation stability Optoelectronic property

INVESTIGATION ON TWO-BODY WEAR OF AUSTENITIC MANGANESE STEEL ThROUGh NUMERICAL qUADRATURE

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Acta Metallurgica Sinica(English Letters) 2004年第3期17卷 307-310页

作者： J.P.Xie h.L.Yuan A.q.wang W.Y.wang Y.R.Zhao School of Materials Science and Engineering Henan University of Science and Technology Luoyang 471003 China China International Trust and Investment Corporation heavy Machinery Co. Ltd. Luoyang 471003China

The mathematic calculation on two--body wear of austenitic manganese steel has been performed by means of the elastic contact theory,stress interferometer and *** distribution in contacted area was calculated and the mechanism on two--body wear has been investigated through numerical *** show that two--body wear is mainly plowing wear the cracks of abrasive dust originates from the region between 0.2αand 0.5α(αis radius of contacted round).Driving force to make crack extension along y axis is T_(yzmax)and extension direction is 45°with *** forces to make crack extension along x axis is alternativeσ_x and T_(yzmax),the direction of crack extension is 37°with horizon.

关键词： mathematic calculation manganese steel two-body wear

Effect of grain size on fatigue cracking at twin boundaries in a CoCrFeMnNi high-entropy alloy

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Journal of Materials Science & Technology 2020年第4期39卷 1-6页

作者： A.G.wang X.h.An J.Gu X.G.wang L.L.Li W.L.Li M.Song q.q.Duan Z.F.Zhang X.Z.Liao School of Aerospace Mechanical&Mechatronic EngineeringThe University of Sydne0ySydneyAustralia State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Materials Fatigue and Fracture Division Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Max-Planck-Institut für Eisenforschung Max-Planck-Stra?e 140237 DüsseldorfGermany

The fatigue cracking behavior at twin boundaries(TBs)in a Co Cr Fe Mn Ni high-entropy alloy with three different grain sizes was systematically investigated under low-cycle *** of grain size,the change from slip band cracking to TB cracking occurred with increasing the difference in the Schmid factors(DSF)between matrix and ***,the required critical DSF for the transition of the dominant cracking mode decreases with decreasing grain size due to the reduced slip band spacing that increases the impingement sites on the TBs and facilitates the coalescence of defects and voids to initiate TB cracks.

关键词： high-entropy alloy Fatigue cracking Twin boundary Slip band Grain size

A Study on Nanoparticle Aerosol Filtration via Different Fibrous Filters by Using CFD Approach

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Journal of Donghua University(English Edition) 2006年第5期23卷 97-100页

作者： q.wang B.Maze h.Vahedi Tafreshi B.Pourdeyhimi Nonwovens Cooperative Research Center North Carolina State University Raleigh NC 27695-8301 Fiber and Polymer Science Program North Carolina State University Raleigh NC 27695-8301 Nonwovens Cooperative Research Center North Carolina State University Raleigh NC 27695-8301

Fibrous filters such as nonwoven media are generally characterized by their collection efficiency and pressure drop. The traditional computational studies in this area typically based on unrealistic over-simplified geometries with the fibers placed in a lattice perpendicular to the flow. This paper describes the filter properties made of different Nonwoven materials by using Computational Fluid Dynamics （CFD） approach. In this study, for the first time, a virtual 3- D web is generated based on the fiber orientation information obtaining from analyzing microscopic images of both long-fiber and short-fiber nonwoven structures. Pressure drop and collection efflcicucy of our virtual filter are simulated and compared with the previous analytical and numerical models as well as experiment.

关键词： permeability CFD simulation nonwoven.