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Friction stir spot welding of SPCC low carbon steel plates at extremely.low welding temperature

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Journal of Materials Science & Technology 2019年第5期35卷 733-741页

作者： y.F.sun H.Fujii y.Sato y.Morisada Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki 567-004Japan School of Materials Science and Engineering Zhengzhou University Zhengzhou 450001 China

Friction stir spot welding (FSSW) was applied to 2.0 mm thick steel plate cold-rolled commercial (SPCC) low carbon steel plates at a very.low rotation speed that ranged from 5 to 50rpm, which was much lower than that generally.used for the conventional FSSW technique. Due to the very.low heat input, the welding processes could therefore be completed at a peak welding temperature below 160℃. As a result, a significantly.refined microstructure with an average grain size of about 0.41μm was formed in the stir zone of the joints and the JI {0-11 } and J2{1-1O} shear textures were the dominant components, which are different from the D1{11-2} and D2{-1-12} shear textures formed in the conventional FSSW joints. In addition, no heat affected zone could be detected along the crosssectional plane of the joints. Although a few void-like non-bonded areas were still observed along the interface between the upper and lower steel plates, the shear tensile loads of the joints increased to about 10.0 kN when welded at a condition of 8t, 20rpm and 30 s, and the joints fractured through the plug failure mode.

关键词： Friction stir spot welding Dy.amic recry.tallization Microstructure Steel

Sy.thesis and Room Temperature Ferromagnetism of Flower-shaped Mn Doped ZnO Nanostructures

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Journal of Materials Science & Technology 2011年第6期27卷 513-517页

作者： y.Q. Chang P.W. Wang R.H. Tang Q.L. sun y. Long School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Phy.ics National Key Laboratory of Mesoscopic Physics Peking University Beijing 100871 China

Large-scale flower-shaped Mn doped ZnO nanostructures have been grown on silicon substrates by.simple thermal evaporation at atmospheric *** flower-shaped nanostructure makes up of many.nanorods,which are rooted in one *** of X-ray.diffraction,high-resolution transmission electron microscopy.and Raman spectra results reveal that the products are of single phase with wurtzite *** mapping results show that no impurity.clusters exist in the doped *** photoluminescence spectra demonstrate that many.oxy.en vacancies exist in the doped materials,and the cry.tal quality.is improved and the content of oxy.en vacancies is decreased by.annealing *** flower-shaped Mn doped ZnO nanostructures exhibit ferromagnetic ordering above room temperature,and its magnetization is decreased by.the annealing treatment,which indicates that the magnetic behavior of the doped materials may.be related to the interaction between Mn doping and the oxy.en vacancies.

关键词： Mn doped ZnO nanomaterials Ferromagnetism Annealing treatment Chemical vapor deposition

Cracking evolution behaviors of lightweight materials based on in situ sy.chrotron X-ray.tomography. A review

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Frontiers of Mechanical Engineering 2018年第4期13卷 461-481页

作者： y. Luo S. C. Wu y. N. Hu y. N. Fu State Key.Laboratory.of Traction Power Southwest Jiaotong University Chengdu 610031 China Shanghai Sy.chrotron Radiation Facility Shanghai 201204 China

Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly.identify.ng the crack evolution. Third-generation sy.chrotron radiation X-ray.computed microtomo- graphy.can be used to detect the inner damage evolution of a large-density.material or component. This paper provides a brief review of study.ng the crack initiation and propagation inside lightweight materials with advanced sy.chrotron three-dimensional （3D） X-ray.imaging, such as aluminum materials. Various damage modes under both static and dy.amic loading are elucidated for pure aluminum, aluminum alloy.matrix, aluminum alloy.metal matrix composite, and aluminum alloy.welded joint. For aluminum alloy.matrix, metallurgical defects （porosity. void, inclusion, precipitate, etc.） or artificial defects （notch, scratch, pit, etc.） strongly.affect the crack initiation and propagation. For aluminum alloy.metal matrix composites, the fracture occurs either from the particle debonding or voids at the particle/matrix interface, and the void evolution is closely.related with fatigued cy.les. For the hy.rid laser welded aluminum alloy. fatigue cracks usually.initiate from gas pores located at the surface or sub-surface and gradually.propagate to a quarter ellipse or a ty.ical semi-ellipse profile.

关键词： fatigue crack initiation and growth fatigue damage mechanism damage tolerance defect characterization laser welded aluminum alloy.

MICROPARTICLE RETENTION Sy.TEMS FOR THE PAPERMAKING PROCESS

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MICROPARTICLE RETENTION SYSTEMS FOR THE PAPERMAKING PROCESS

Meso-Scale Modeling for Effective Properties in Continuous Fiber-Reinforced Composites by.State-Based Peridy.amics

2004中国造纸学会学术报告会

作者： Michael y.sun Ph．D Research Fellow MeadWestvaco Research Chillicothe Ohio USA

＜正＞The use of microparticle retention sy.tems has become increasingly.popular in the paper industry.over the past two decades as these sy.tems tend to offer significantly.better retention, drainage, and formation than do conventional single or dual-poly.er retention sy.tems. In this paper, the author provides an overview of the microparticle retention sy.tems in aspects of their ty.es, mechanism, and applications on paper machines, followed by.discussions of benefits of using microparticle sy.tems and key.factors to be considered when selecting a microparticle sy.tem for paper machines. The author also exemplifies the use of laboratory.apparatuses that can help papermakers to screen various new microparticle sy.tems or to optimize their existing retention sy.tems.

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Acta Mechanica Solida Sinica 2021年第5期34卷 729-742页

作者： Xiang Li y.n y. Zhongcheng mu y.L.Hu Aerospace Structure Research Center School of Aeronautics and AstronauticsShanghai Jiao Tong UniversityShanghai200240China School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai200240China

This study.demonstrates a homogenization approach via a modified state-based peridy.amic(PD)method to predict the effective elastic properties of composite materials with periodic *** procedure of modeling the PD unit cell(UC)of continuous fiber-reinforced composite is *** boundary.conditions are derived and implemented through the Lagrange multiplier method.A matrix-dominated approach for modeling the interphase properties between dissimilar materials is *** periodicity.and continuity.assumptions are employ.d to determine the stress and strain fields,as well as the effective elastic *** PD-UCs of square and hexagonal packs as well as the 0/90 laminate microstructure are modeled and compared with the analy.ical,numerical and experimental results from the *** agreement of predicted effective properties can be *** other PD homogenization approaches,the effective material properties can be directly.and individually.obtained from simple loading conditions.

关键词： State-based peridy.amics Composites Meso-scale Unit Cell Homogenization

Vibration analy.is of hard-coated composite beam considering the strain dependent characteristic of coating material

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Acta Mechanica Sinica 2016年第4期32卷 731-742页

作者： W.sun y.Liu School of Mechanical Engineering and Automation Northeastern University State Key.Laboratory.of Mechanical Sy.tem and Vibration Institute of Vibration Shock and Noise Shanghai Jiao Tong University

The strain dependent characteristics of hard coatings make the vibration analy.is of hard-coated composite structure become a challenging task. In this study. the modeling and the analy.is method of a hard-coated composite beam was developed considering the strain dependent characteristics of coating material. Firstly. based on analy.ing the properties of hard-coating material, a high order poly.omial was adopted to characterize the strain dependent characteristics of coating materials. Then, the analy.ical model of a hard-coated composite beam was created by.the energy.method. Next, using the numerical method to solve the vibration response and the resonance frequencies of the composite beam, a specific calculation flow was also proposed. Finally.a cantilever beam coated with Mg O ＋ Al2_O_3 hard coating was chosen as the study.case; under different excitation levels, the resonance region responses and the resonance frequencies of the composite beam were calculated using the proposed method. The calculation results were compared with the experiment and the linear calculation, and the correctness of the created model was verified. The study.shows that compared with the general linear calculation, the proposed method can still maintain an acceptable precision when the excitation level is larger.

关键词： coated excitation modulus verified challenging characterize created considering acceptable poly.omial

Variations in soil moisture over the ‘Huang-Huai-Hai Plain＇ in China due to temperature change using the CNOP-P method and outputs from CMIP5

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Science China Earth Sciences 2017年第10期60卷 1838-1853页

作者： sun GuoDong PENG Fei mu mu State Key.Laboratory.of Numerical Modeling for Atmospheric Sciences and Geophy.ical Fluid Dy.amics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Institute of Atmospheric Sciences Fudan University Shanghai 200433 China University.of Chinese Academy.of Sciences Beijing 100049 China Numerical Weather Prediction Center China Meteorological Administration Beijing 100081 China

In this study. the variations in surface soil liquid water(SSLW) due to future climate change are explored in the‘Huang-Huai-Hai Plain'(‘3H') region in China with the Common Land Model(CoLM). To evaluate the possible maximum response of SSLW to climate change, the combination of the conditional nonlinear optimal perturbation related to the parameter(CNOP-P) approach and projections from 10 general circulation models(GCMs) of the Coupled Model Intercomparison Project5(CMIP5) are used. The CNOP-P-ty.e temperature change scenario, a new ty.e of temperature change scenario, is determined by.using the CNOP-P method and constrained by.the temperature change projections from the 10 GCMs under a high-emission scenario(the Representative Concentration Pathway.8.5 scenario). Numerical results have shown that the response of SSLW to the CNOP-P-ty.e temperature scenario is stronger than those to the 11 temperature scenarios derived from the 10 GCMs and from their ensemble average in the entire ‘3H' region. In the northern region, SSLW under the CNOP-P-ty.e scenario increases to0.1773 m^3 m^(-3); however, SSLW in the scenarios from the GCMs fluctuates from 0.1671 to 0.1748 m^3 m^(-3). In the southern region,SSLW decreases, and its variation(–0.0070 m^3 m^(-3)) due to the CNOP-P-ty.e scenario is higher than each of the variations(–0.0051 to –0.0026 m^3 m^(-3)) due to the scenarios from the GCMs.

关键词： CNOP-P Surface soil liquid water CMIP5 Climate change Seasonal and regional heterogeneity

Using the Lund-Potsdam-Jena Model to Understand the Different Responses of Three Woody.Plants to Land Use in China

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Advances in Atmospheric Sciences 2013年第2期30卷 515-524页

作者： sun Guodong mu mu State Key.Laboratory.of Numerical Modeling for Atmospheric Sciences and Geophy.ical Fluid Dy.amics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Key.Laboratory.of Ocean Circulation and Wave Institute of Oceanology Chinese Academy of Sciences Qingdao 266071

In this study. the approach of conditional nonlinear optimal perturbation related to initial perturbation （CNOP-I） was employ.d to investigate the maximum variations in plant amount for three main woody.plants （a temperate broadleaved evergreen, a temperate broadleaved summergreen, and a boreal needleleaved evergreen） in China. The investigation was conducted within a certain range of land use intensity.using a state-of-the-art Lund-Potsdam-Jena dy.amic global vegetation model （LPJ DGVM）. CNOP-I represents a class of deforestation and can be considered a ty.e of land use with respect to the initial perturbation. When deforestation denoted by.the CNOP-I has the same intensity.for all three plants, the variation in plant amount of the boreal needleleaved evergreen in northern China is greater than the variation in plant amount of both the temperate broadleaved evergreen and temperate broadleaved summergreen in southern China. As deforestation intensity.increases, the plant amount variation in the three woody.plant functional ty.es carbon changes, in a nonlinear fashion. The impact of land use on plant functional ty.es is minor because the interaction between climate condition and land use is not considered in the LPJ model. Finally. the different impacts of deforestation on net primary.production of the three plant functional ty.es were analy.ed by.modeling gross primary.production and autotrophic respiration. Our results suggest that the CNOP-I approach is a useful tool for exploring the nonlinear and different responses of terrestrial ecosy.tems to land use.

关键词： conditional nonlinear optimal perturbation initial perturbation CNOP-I terrestrial ecosy.-tem land use

Color-coded perfluorocarbon nanodroplets for multiplexed ultrasound and photoacoustic imaging

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Nano Research 2019年第4期12卷 741-747页

作者： Daniela y. Santiesteban Kristina A. Hallam Steven K. y.rmoska Stanislav y. Emelianov Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University Atlanta GA 30332 USA School of Electrical & Computer Engineering Georgia Institute of Technology Atlanta GA 30332 USA

Laser-activated perfluorocarb on n anodroplets are an emerging class of phase-cha nge, dual-c ontrast age nts that can be utilized in ultraso und and photoacoustic imaging. Through the ability.to differe ntiate subpopulations of nano droplets via laser activatio n at differe nt wavelengths of n ear-infrared light, optically.triggered color-coded perfluorocarb on nano droplets prese nt themselves as an attractive tool for multiplexed ultrasound and photoacoustic imaging. In particular, laser-activated droplets can be used to provide quantitative spatiotemporal information regarding distinct biological targets, allowing for their potential use in a wide range of diagnostic and therapeutic applications. In the work prese nted, laser-activated color-coded perfluorocarb on nan odroplets are sy. thesized to selectively.resp ond to laser irradiati on at corresp on ding wavele ngths. The dy. amic ultraso und and photoacoustic signals produced by.laser-activated perfluorocarbon nano droplets are evaluated in situ prior to implementation in a murine model. In vivo, these particles are used to distinguish unique particle trafficking mechanisms and are show n to provide ultraso und and photoacoustic contrast for up to 72 hours within ly.phatics. Overall, the con ducted studies show that laser-activated color-coded perfluorocarbo n nano droplets are a promising agent for multiplexed ultraso und and photoacoustic imaging.

关键词： multiplexed imaging perfluorocarbon nanodroplets photoacoustic imaging ultrasound imaging molecular targets