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A Fourier Spectral Moving Mesh Method for the Cahn-Hilliard Equation with Elasticity

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Communications in Computational Physics 2009年第2期5卷 582-599页

作者： w.M.Feng P.Yu S.Y.Hu Z.K.Liu q.Du L.q.chen Department of Materials Science and Engineering Pennsylvania State UniversityUniversity ParkPA 16802USA Department of Mathematics Pennsylvania State UniversityUniversity ParkPA 16802USA Pacific Northwest National Laboratory RichlandWA 99354USA

In recent years,Fourier spectral methods have emerged as competitive numerical methods for large-scale phase field simulations of microstructures in computational materials *** further improve their effectiveness,we recently developed a new adaptive Fourier-spectral semi-implicit method(AFSIM)for solving the phase field equation by combining an adaptive moving mesh method and the semi-implicit Fourier spectral *** this paper,we present the application of AFSIM to the Cahn-Hilliard equation with inhomogeneous,anisotropic *** implementations and test examples in both two and three dimensions are considered with a particular illustration using the well-studied example of mis-fitting particles in a solid as they approach to their equilibrium *** is shown that significant savings in memory and computational time is achieved while accurate solutions are preserved.

关键词： Phase field diffuse interface moving mesh adaptive mesh Fourier-spectral method adaptive spectral method Cahn-Hilliard equation elasticity

A hidden precipitation scenario of theθ’-phase in Al-Cu alloys

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Journal of Materials Science & Technology 2021年第16期75卷 126-138页

作者： L.Zhou C.L.wu P.Xie F.J.Niu w.q.Ming K.Du J.H.chen center for high-resolution electron microscopy college of materials science and engineeringhunan universitychangshahunan410082china shenyang national laboratory for materials science institute of metal researchchinese academy of sciences.shenyan7.110016china

Al-Cu binary alloys are important and interesting industry *** to date,the formation mechanisms of the key strengthening precipitates,namedθ’-phase,in the alloys are still ***,we report that for non-deformed bulk Al-Cu alloys theθ’-phase actually has its own direct precursors that can form only at elevated aging temperature(>ca.200℃).These high-temperature precursors have the same plate-like morphology as theθ’-phase precipitates but rather different *** imaging reveals that they have a tetragonal structure with a=0.405 nm and c=1.213 nm,and an average composition of Al_(5-x)Cu_(1+x)(0≤xwith the *** precursor phase may initiate with a composition of Al5 Cu and evolve locally towards Al_(4)Cu_(2)in composition,eventually leading to a consequent structural transformation into theθ’-phase(Al4 Cu2=Al2 Cu).There are evidences that because of their genetic links in structure,such a high-temperature precursor may transform to theθ’-phase without having to change their morphology and interface *** study reveals a well-defined and previously hidden precipitation scenario for theθ’-phase to form in Al-Cu alloys at an elevated aging temperature.

关键词： AlCu alloy Age-hardening Precipitation Electron microscopy

Interface dominated deformation transition from inhomogeneous to apparent homogeneous mode in amorphous/amorphous nanolaminates

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Journal of Materials Science & Technology 2022年第4期99卷 178-183页

作者： Z.q.chen M.C.Li J.S.Cao F.C.Li S.w.Guo B.A.Sun H.B.Ke w.H.wang Songshan Lake Materials Laboratory Dongguan 523808PR China Institute of Physics Chinese Academy of SciencesBeijing 100190PR China Institute of Materials Engineering Nanjing UniversityNantong 226019PR China School of Physics Science and Technology Xinjiang UniversityXinjiang 830046PR China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049PR China State Key Laboratory for Mechanical Behavior of Material Xi'an Jiaotong UniversityXi’an 710049PR China

The amorphous/amorphous nanolaminates(A/ANLs)have aroused great attentions owing to their tunable structure and enhanced mechanical ***,the plastic deformation mechanism of A/ANLs have yet been ***,we systematically examined the mechanical properties and deformation behavior of series of NiNb/ZrCuNi Al A/ANLs via nanoindentaion *** was found that both the amount and morphology of amorphous/amorphous interface(A/AIs)played crucial roles in the plastic deformation of A/*** and straighter A/AIs facilitated multiple shear banding deformation,of which the hardness increased with decreasing layer thickness,as the A/AIs hindered the propagation of shear bands(SBs).whilst,more and wavier A/AIs promoted homogeneous deformation,of which the hardness stayed at a much lower value and was relatively irrelevant with the layer thickness,for the promoted activation of shear transformation zones by A/*** results provide guidance for modifying the mechanical properties of amorphous alloys with interface engineering design.

关键词： Amorphous alloys Nanolaminates Shear bands Hardness Interface

Simulation study on the effect of pre-evacuation time and exit width on evacuation

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Chinese Science Bulletin 2006年第11期51卷 1381-1388页

作者： CHU Guanquan SUN Jinhua wANG q ingsong chen Sining State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China

Occupant pre-evacuation time is often oversimplified into an explicit value in evacuation calculation. In fact, it is not an explicit value but a random variable following some kind of probability distribution. In order to analyze the importance of pre-evacuation time in evacuation calculation, Grid- Flow evacuation model is utilized to study the effect of pre-evacuation time on evacuation under different occupant densities and exit widths in a single room scenario. The evacuation time calculated by using normal pre-evacuation distribution is compared with that calculated by explicit pre-evacuation time. Two faults are presented when pre-evacuation time is considered as an explicit value. The theory of con- gestion and queue is presented to analyze the cal- culation results. Moreover, this paper also presents probability distribution of the total evacuation time when the pre-evacuation time follows normal distri- bution. The results show that the evacuation time is dominated by pre-evacuation time and hardly de- pendent on occupant density when the mean pre- evacuation time is long. For long mean pre-evacua- tion time, low occupant density or wide exit, when pre-evacuation time follows normal distribution, the total evacuation time also follows normal distribution.

关键词：火灾预疏散时间正态分布出口宽度居住密度模拟研究

Effects of Sn^+ Ion Implantation on the Thermoelectric Properties of n-type Lead Telluride

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Journal of Materials Science & Technology 1999年第5期15卷 483-485页

作者： Shen, q Zhang, LM Li, JG Tu, R chen, LD wuhan Univ Technol State Key Lab Mat Synth & Proc Wuhan 430070 Peoples R China Tohoku Univ Inst Mat Res Aoba Ku Sendai Miyagi 98077 Japan

The n-type PbTe doped with 0.05 mol fraction PbI2 was hot-pressed, and the sintered samples were implanted by Sn+ ions at 200 KeV with doses of 6x10(16) and 1x10(17) ions/cm(2). The effect of Sn+ implantation on thermoelectric properties was then investigated. The results show that Sn+ ion implantation can modify thermoelectric properties of the n-type PbTe and greatly improve the dimensionless figure-of-merit.

关键词： Effects of Sn type Ion Implantation on the Thermoelectric Properties of n-type Lead Telluride

Insights on the use of biosimilars in the treatment of inflammatory bowel disease

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world Journal of Gastroenterology 2017年第11期23卷 1932-1943页

作者： Michael K Zheng David q Shih Gary C chen F.widjaja Foundation Inflammatory Bowel and Immunobiology Research InstituteCedars-Sinai Medical Center Comprehensive Digestive Institute of Nevada

Biologic therapy, such as those that target tumor necrosis factor(TNF) signaling, has proven to be an efficacious method of treatment for patients with inflammatory bowel disease(IBD) with regards to symptom management and mucosal healing. However, the rising prevalence of IBD worldwide and the everincreasing burden of biologic pharmaceuticals in the health care industry is alarming for insurance companies, clinicians, and patients. The impending patent expiry and the relatively high costs of biologics, particularly anti-TNF agents, have paved the way for biosimilar development for IBD. The United States Food and Drug Administration defines a biosimilar as a biological product that is highly similar to its reference medicinal product, with no clinically meaningful differences in terms of safety, purity, and potency. The hope with biosimilars is that their entry into the market will be able to drive competition between pharmaceutical companies to reduce prices like that of the generic market, and that access to appropriate biologic treatments for IBD patients is increased in the long-term. Yet, there are challenging issues such as indication extrapolation and interchangeability that are still being debated in the field of IBD and must be addressed in future issued guidance. This review will discuss the issues and implications concerning the use of biosimilar therapy for IBD.

关键词： Biosimilar Biologic Inflammatory bowel disease Ulcerative colitis Crohn’s disease Indication extrapolation Interchangeability

Reduction effect of final-pass heavy reduction rolling on the texture development,tensile property and stretch formability of ZwK100 alloy plates

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Journal of Materials Science & Technology 2022年第16期111卷 211-223页

作者： B.q.Shi L.Y.Zhao X.L.Shang B.H.Nie D.C.chen C.q.Li Y.q.cheng School of Materials Science and Hydrogen Energy Foshan UniversityFoshan 528000China School of Materials and Energy Guangdong University of TechnologyGuangzhouGuangdong 510006China GD Midea Air-Conditioning Equipment Co. Ltd.Foshan 528311China Guangdong Key Laboratory of Hydrogen Energy Technology Foshan 528000China YunFu(Foshan)R&D Center of Hydrogen Energy Standardization Yunfu 527326China

Obviously planar anisotropy due to‘TD split’orthotropic texture(TD indicates Transverse direction)always exist in the Rare-earth(RE)or Ca containing Mg alloy sheets,which is likely caused by the lowreduction rolling(and annealing)as revealed in our previous *** this work,the as-cast billets of a ZwK100 alloy were subjected to final-pass heavy reduction rolling(FHRR)at 500°C with different reductions(30%-70%)after rough rolling,aiming to investigate the reduction effect on the microstructure and texture *** results show that FHRR with higher reductions above 50%is in favor of shear banding formation but has little effect on the as-deformed texture components,and the excellent formability with single-pass reduction up to 70%is mainly ascribed to the activation of prismatic *** with reduction above 50%and annealing can generate uniform grain structures of~10μm and symmetrical‘oblique-line split’texture in(0001)pole figures,with basal poles tilting by about 50°from ND(Normal direction)towards some oblique-line of TD and RD(Rolling direction)as well as uniform distribution of counter lines as an annular shape,resulting in excellent elongation to failure of~50%and ultra-low planar anisotropyΔr_of~0.1 and high stretch formability(Erichsen value:8.1).The formation‘oblique-line split’texture in(0001)pole figures is mainly correlated with the preferred growth tendency of grains with■//RD,which was suggested to relate to the high mobility of some special boundaries such as 40°-45°■.The influences of starting textures on the mechanical properties,planar anisotropy and related deformation modes,as well as their correlations with the stretch formability were comparatively investigated with the‘TD split’orthotropic texture as a counterpoint.

关键词： Magnesium alloys Texture Plane anisotropy Stretch formability Rolled sheets

EVALUATION OF THE PROBABILITY DISTRIBUTION OF PITTING CORROSION FATIGUE LIFE IN AIRCRAFT MATERIALS

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Acta Mechanica Sinica 2003年第3期19卷 247-252页

作者：王清远 N.KAwAGOISHI q.chen R.M.PIDAPARTI Dept.of Civil Eng.and Mechanics Sichuan UniversityChengdu 610065China

Corrosion and fatigue properties of aircraft materials are known to have a considerable scatter due to the random nature of materials,loading,and environmental conditions.A probabilistic approach for predicting the pitting corrosion fatigue life has been investigated which captures the effect of the interaction of the cyclic load and corrosive environment and all stages of the corrosion fatigue process (*** pit nucleation and growth,pit-crack transition,short- and long-crack propagation).The probabilistic model investigated considers the uncertainties in the initial pit size,corrosion pitting current,and material properties due to the scatter found in the experimental *** Carlo simulations were performed to define the failure probability *** cumulative distribution functions of fatigue life agreed reasonably well with the existing experimental data.

关键词： pitting corrosion fatigue probabilistic modeling fatigue life prediction

Experimental Study and Numerical Simulation of the Casting-Forging Complex Near Net Forming of Alternator Claw-pole

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上海交通大学学报 2004年第Z2期38卷 79-82页

作者： J.L.Song D.J.Hu q.C.wang H.q.chen H.G.Guo School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai200030 China Scool of Materials Science and Engineering Taiyuan Heavy Machinery Institute Taiyuan030024 China School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai200030 China Scool of Materials Science and Engineering Taiyuan Heavy Machinery Institute Taiyuan030024 China Scool of Materials Science and Engineering Taiyuan Heavy Machinery Institute Taiyuan030024 China Scool of Materials Science and Engineering Taiyuan Heavy Machinery Institute Taiyuan030024 China

As a newly developed precision technology, casting-forging complex near net forming process is utilized to produce complex components with a short lead time, low cost and high precision, thus to accelerate the response speed of the market and enhance the competitive power of products. In this paper, the casting-forging complex near net forming process of alternator claw pole was developed and investigated with a combination of experimental and numerical simulation method. qualified near net workpiece was manufactured, mechanical parameter and relative field information during the forming process was also obtained. while the alternator claw-pole is processed with this technology, the forming force is small, the process is short and the quality of forgings is perfect. Therefore, the complex casting-forging near net forming process of claw-pole is an energy and material saving technology, which will have a vast developing and application prospect in the future.

关键词： alternator claw-pole casting-forging near net forming numerical simulation