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FINITE ELEMENT ANALYSIS OF AXIAL FEED BAR ROLLINg

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Acta Metallurgica Sinica(English Letters) 2007年第6期20卷 463-468页

作者： C.g. xu g.h. Liu g.S. Ren Z. Shen C.P. Ma W. W. Ren Beijing Research Institute of Mechanical and Electrical Technology Beijing 100083 China

A flexible technique of hot working of bars by axial feed rolling was introduced. The process deformation, strain field, stress field, and temperature fie M of the parts are analyzed by finite element method （ FEM）-... 详细信息

关键词： axial feed bar rolling deformation FEM (finite element method) stress field strain feld, temperature field

Fiber Bundle Topology Optimization for Surface Flows

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 236-264页

作者： Yongbo Deng Weihong Zhang Jihong Zhu Yingjie xu Jan g Korvink State Key Laboratory of Applied Optics Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China Institute of Microstructure Technology(IMT) Karlsruhe Institute of Technology(KIT)Hermann-von-Helmholtzplatz 176344 Eggenstein-LeopoldshafenGermany

This paper presents a topology optimization approach for the surface flows on variable design *** this approach,the matching between the pattern of a surface flow and the 2-manifold used to define the pattern can be optimized,where the 2-manifold is implicitly defined on another fixed 2-manifold named as the base *** fiber bundle topology optimization approach is developed based on the description of the topological structure of the surface flow by using the differential geometry concept of the fiber *** material distribution method is used to achieve the evolution of the pattern of the surface *** evolution of the implicit 2-manifold is realized via a homeomorphous *** design variable of the pattern of the surface flow and that of the implicit 2-manifold are regularized by two sequentially implemented surface-PDE *** two surface-PDE filters are coupled,because they are defined on the implicit 2-manifold and base manifold,*** surface Navier-Stokes equations,defined on the implicit 2-manifold,are used to describe the surface *** fiber bundle topology optimization problem is analyzed using the continuous adjoint method implemented on the first-order Sobolev *** numerical examples have been provided to demonstrate this approach,where the combination of the viscous dissipation and pressure drop is used as the design objective.

关键词： Fiber bundle Topology optimization 2-manifold Surface flow Material distribution method Porous medium model

Atomistic Investigation of Shock-Induced Amorphization within Micro-shear Bands in hexagonal Close-Packed Titanium

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Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1590-1600页

作者： Z.C.Meng K.g.Wang T.Ali D.Li C.g.Bai D.S.xu S.J.Li A.h.Feng g.J.Cao J.h.Yao Q.B.Fan h.Wang R.Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Interdisciplinary Centre for Additive Manufacturing(ICAM) School of Materials and ChemistryUniversity of Shanghai for Science and TechnologyShanghai 200093China School of Materials Science and Engineering Tongji UniversityShanghai 201804China Key Laboratory for Light-Weight Materials Nanjing Tech UniversityNanjing 210009China National Key Laboratory of Science and Technology on Materials Under Shock and Impact School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401135China

The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics ***,non-uniform plastic deformation was observed in the *** high strain rates,amorphization occurred near the edge of the contact region where severe shear strain induced a large number of stacking faults(SFs)and *** contrast,the central part of the contact region underwent less deformation with significantly fewer ***,instead of amorphization by consuming SFs and dislocations,there was a gradual increase in the density of dislocations and SFs during the process of *** local amorphous regions eventually grew into shear bands.

关键词： Shock compression Amorphization Shear band Titanium Molecular dynamics

Laboratory evaluation of high-friction thin overlays for pavement preservation

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Frontiers of Structural and Civil Engineering 2024年第6期18卷 936-948页

作者： Ouming xu Rentao xu Lintong JIN School of highway Chang’an UniversityXi’an 710064China School of Materials Science and Engineering Chang’an UniversityXi’an 710061China

Traditional asphalt concrete(AC)and stone matrix asphalt(SMA),which are used as thin asphalt overlays,are common maintenance strategies to enhancing ride quality,skid resistance,and ***,several studies have used a novel asphalt mixture known as a high-friction thin overlay(hFTO)to improve surface ***,it remains uncertain whether the laboratory properties of hFTO differ significantly from those of conventional *** study aims to evaluate the laboratory properties of hFTO mixtures and compare them with those of AC and *** mixtures with nominal maximum size of 9.5 mm were produced in the laboratory,and performance tests were conducted,including wheel tracking test,low temperature flexural creep test,moisture susceptibility test,Cantabro Abrasion Test,Marshall Test,sand patch test,British pendulum test,and indoor tire-rollingdown *** results showed that the hFTO exhibited a lower tire/pavement noise than the AC and ***,hFTO had superior high-temperature stability,larger macro texture,and higher skid resistance in comparison to those of AC,but lower than those of ***,hFTO mixtures may be considered a suitable replacement for traditional AC mixtures in regions where skid resistance and noise reduction are concerns.

关键词： road engineering pavement maintenance high friction thin overlay performance skid resistance tire/pavement noise

Nanoindentation responses of NiCoFe medium-entropy alloys from cryogenic to elevated temperatures

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Journal of Iron and Steel Research International 2024年第8期31卷 2068-2077页

作者： Qin-qin xu Kamran Karimi Amirhossein h.Naghdi Wen-yi huo Chong Wei Stefanos Papanikolaou NOMATEN Centre of Excellence National Centre for Nuclear ResearchOtwock 05-400MazowszePoland College of Mechanical and Electrical Engineering Nanjing Forestry UniversityNanjing 210037JiangsuChina Science and Technology on Thermo Structural Composite Materials Laboratory Northwestern Polytechnical UniversityXi'an 710072ShaanxiChina School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072ShaanxiChina

NiCoFe alloy,a medium-entropy alloy,shows potential for applications in extreme ***,there is a theoretical barrier concerning the unclear understanding of its high-temperature dislocation motion *** load response exhibits distinct signatures relevant to thermal activation,most notably a decrease in critical force(i.e,softening)from cryogenic to elevated temperatures,e.g.,from 200 to 1000 *** onset of plasticity is characterized by the nucleation of stacking faults and prismatic loops at low temperatures,whereas the surface nucleation of Shockley partial dislocations dominates plasticity at elevated *** show that thermal effects lead to non-uniform atom pile-ups and control the rate of phase transformation with increasing indentation *** findings in this work extend the understanding of the mechanical response of NiCoFe alloys under indentation at different temperatures,shedding light on the underlying dislocation motion mechanisms and surface deformation *** observed transformation-induced plasticity mechanism has implications for the properties of medium-entropy alloys and their potential applications in extreme environments.

关键词： Orientation Dislocations Mechanical behaviors Phase transition

Biotreatment of incinerated bottom ash and biocementation of sand blocks using soybean urease

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第1期25卷 36-46页

作者： Xiaoniu YU Yidong xu Jiangsu Key Laboratory of Construction Materials Southeast UniversityNanjing211189China School of Civil Engineering and Architecture NingboTech UniversityNingbo315100China

Because of the high cost of cultivating urease-producing bacteria(UPB),this paper proposes soybean-urease-induced carbonate precipitation(SUICP)as a novel biocement for treatment of nickel contaminants and cementation of sandy *** found the optimal soaking time and soybean-powder content to be 30 min and 130 g/L,respectively,based on a standard of 5 U of urease *** most efficient removal of nickel ions is obtained with an ideal mass ratio of urea to nickel ions to soybean-powder filtrate(SPF)of 1:2.4:*** removal efficiency of nickel ions can reach 89.42%when treating 1 L of nickel-ion solution(1200 mg/L with the optimal mass ratio).In incinerated bottom ash(IBA),the removal efficiency of nickel ions is 99.33%with the optimal mass *** biocemented sandy soil,the average unconfined compressive strength(UCS)of sand blocks cemented with soybean urease-based biocement can reach 118.89 kPa when the cementation level is ***,the average content of CaCO_(3)in sand blocks is 2.52%.As a result,the SUICP process can be applied to remove heavy metal ions in wastewater or solid waste and improve the mechanical properties of soft soil foundations.

关键词： Biocement Soybean-powder filtrate(SPF) Removal efficiency Sandy soil Unconfined compressive strength(UCS)

Achieving superior performance in powder-metallurgy near-βtitanium alloy by combining hot rolling and rapid heat treatment followed by aging

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Journal of Materials Science & Technology 2024年第4期171卷 24-36页

作者： Fucheng Qiu Tuo Cheng Yuchao Song Orest M.Ivasishin Dmytro g.Savvakin guangyu Ma huiyan xu College of Materials Science and Engineering Jilin UniversityChangchun 130025China International Center of Future Science Jilin UniversityChangchun 130025China g.V.Kurdyumov Institute for Metal Physics KyivUkraine College of Biological and Agricultural Jilin UniversityChangchun 130025China

heat treatment plays an important role in tailoring the mechanical properties of powder-metallurgy(PM)titanium ***,only limited work about the rapid heat treatment(RhT)of PM titanium alloys has been *** this work,RhT was applied to PM Ti-5Al-5Mo-5V-1Cr-1Fe alloy after hot rolling to study the evolution of its mechanical properties and the influence of residual pores on its *** hot rolling and annealing,a fine and uniformα+βstructure with few residual pores is *** RhT,the primaryαdissolves gradually and completes in theβregion,and theβgrains then grow,resulting in the continuous decrease in elongation after ***,the tensile strength first increases and then decreases with increasing RhT temperature,owing to the increase in volume fraction of secondaryαinα+βregion and theβgrain growth inβ*** contrast to the RhT of cast-and-wrought titanium,the negative influence of residual pores lowers the RhT temperature for obtaining the highest tensile strength to a temperature below theβ-transus *** the negative influence of the residual pores,retained primaryαand fineβgrains with fine secondaryαinside contribute to achieving a good strength/ductility balance(1570 MPa and 6.1%,respectively).Addi-tionally,although at higher cycles to failure,the negative influence of residual pores increases as it affects the crack initiation zone at the subsurface,the good resistance of secondaryαto fatigue crack propaga-tion still enhances the fatigue strength considerably(about 300 MPa).This work suggests a cost-effective strategy to produce titanium alloys with high performance.

关键词： Rapid heat treatment Powder metallurgy Mechanical properties Near-βtitanium Residual pores

The storage and utilization of carbohydrates in response to elevation mediated by tree organs in subtropical evergreen broad-leaved forests

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Forest Ecosystems 2024年第1期11卷 52-61页

作者： Bin xu xueli Jiang Yingying Zong g.geoff Wang Fusheng Chen Zhenyu Zhao Xiangmin Fang Key Laboratory of National Forestry and grassland Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed College of ForestryJiangxi Agricultural UniversityNanchang330045China Jiulianshan National Observation and Research Station of Chinese Forest Ecosystem College of ForestryJiangxi Agricultural UniversityNanchang330045China Department of Forestry and Environmental Conservation Clemson UniversityClemsonSC29634USA

global climate change can affect tree growth and carbon sink function by influencing plant carbohydrate synthesis and utilization,while elevation can be used as an ideal setting under natural conditions to simulate climate change *** effect of elevation on tree growth may depend on organ ***,the allocation patterns of nonstructural and structural carbohydrates(NSCs and SCs,respectively)in different tree organs and their response to elevation remain *** selected four dominant tree species,Schima superba,Castanopsis eyrei,Castanopsis fargesii and Michelia maudiae,along an elevation gradient from 609 to 1,207 m in subtropical evergreen broad-leaved forests and analyzed leaf,trunk,and fine root NSCs,carbon(C),nitrogen(N)and phosphorus(P)concentrations and the relative abundance of *** NSCs increased initially and then decreased,and trunk NSCs increased with increasing ***,root NSCs decreased with increasing *** relative abundance of SCs in leaves and trunks decreased,while the relative abundance of root SCs increased with increasing *** significant correlations between SCs and NSCs in leaves were detected,while there were negative correlations between SCs and NSCs in trunks,roots,and all *** partitioning analysis indicated that plant C/N and C/P were the main predictors of changes in SCs and *** results suggest that tree organs have divergent responses to elevation and that increasing elevation will inhibit the aboveground part growth and enhance the root growth of trees.A tradeoff between the C distribution used for growth and storage was confirmed along the elevation gradient,which is mainly manifested in the"sink"organs of *** results provide insight into tree growth in the context of global climate change scenarios in subtropical forest ecosystems.

关键词： Nonstructural carbohydrates Structural carbohydrates Elevation Subtropical evergreen broad-leaved forests Tree organs

Bio-inspired inorganic-protein coating on Mg-based biomaterials for bioengineering applications

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Science China Materials 2024年第5期67卷 1678-1680页

作者： xuwen Peng haolan xu Department of Chemistry Engineering Tsinghua UniversityBeijing100084China Department of Chemical and Materials Engineering University of AlbertaEdmontonAlbertaT6G 1H9Canada Future Industries Institute UniSA STEMUniversity of South AustraliaMawson Lakes CampusAdelaideSouth Australia5095Australia

Developing smart and advanced functional materials inspired by the unparalleled complexity and efficiency of biological tissues has received much attention across various *** alloys,particularly pure magnesium,have emerged as notable candidates in orthopedics and dentistry due to their exceptional biocompatibility,degradability,and ability to promote bone regeneration[1].however,the highly reactive chemical nature of magnesium and its rapid degradation upon exposure to water.

关键词： coating alloys magnesium