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Modeling and numerical investigation of slow crack growth and crack arrest in ceramic polycrystals

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Theoretical & Applied Mechanics Letters 2013年第5期3卷 53-57页

作者： Bassem El Zoghbi Rafael Estevez Christian Olagnon Laboratoire SIMAP UMR CNRS 5266 Grenoble-INP UJF Universite' de Grenoble laboratoire MATEIS UMR CNRS 5510 INSA Lyon Universite' de Lyon69621 France

ntergranular slow crack growth in zirconia polycrystal is described with a cohesive zone model that simulate mechanically the reaction-rupture mechanism underlying stress and environ- mentally assisted failure. A 2D polycrystal is considered with cohesive surfaces inserted along the grain boundaries. The anisotropic elastic modulus and grain-to-grain misorientation are accounted for together with an initial stress state related to the processing. A minimum load threshold is shown to originate from the onset of the reaction-rupture mechanism to proceed where a minimum traction is reached locally and from the magnitude of the initial compression stresses. This work aims at providing reliable predictions in long lasting applications of ceramics.

关键词： zirconia ceramic slow crack growth cohesive zone intergranular failure

Vickers and Knoop Micro-hardness Behavior of Coarse-and Ultrafine-grained Titanium

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Journal of Materials Science & Technology 2010年第10期26卷 904-907页

作者： K.P.Sanosh A.Balakrishnan L.Francis T.N.Kim Department of Information and Electronic Materials Engineering College of EngineeringPaichai University Laboratoire SIMAP GPM2 Grenoble-INPUJFCNRS 101 Rue de la PhysiqueBP46 38402 Saint Martin d'He' res CedexFrance University of Genova Department of Chemistry and Industrial Chemistry

The present study focuses on the relationship of hardness with grain size for commercially pure titanium （CpTi） and ultra fine grained titanium （UFG-Ti） produced by equal channel angular process （ECAP） of Cp-Ti）.Vickers and Knoop indentations of UFG-Ti at different loads was ～2.5 times harder than those of Cp-Ti.Xray diffraction （XRD） analysis showed peak broadening in UFG-Ti due to reduced grain size and micro-lattice strains.Scanning electron microscopy （SEM） revealed that ECAP had reduced the grain size of Cp-Ti by ～10 times.Weibull statistics showed UFG-Ti with lower dispersion in hardness values compare to Cp-Ti indicating a more uniform microstructure.

关键词： Vickers Knoop Hardness Ultrafine-grained Titanium

Soil-atmosphere interaction in earth structures

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 35-49页

作者： Yujun Cui laboratoire Navier Ecole des Ponts ParisTechFrance

The soil-atmosphere interaction was investigated through laboratory testing,field monitoring and numerical monitoring.In the laboratory,the soil water evaporation mechanisms were studied using an environmental chamber equipped with a large number of sensors for controlling both the air parameters and soil parameters.Both sand and clay were considered.In case of sand,a dry layer could be formed during evaporation in the near surface zone where the suction corresponded to the residual volumetric water content.The evaporative surface was situated at a depth where the soil temperature was the lowest.In case of clay,soil cracking occurred,changing the evaporative surface from one-dimensional to three-dimensional nature.The suctionbased evaporation model was adapted to take these phenomena into account by adopting a function of dry layer evolution in the case of sand and by adopting a surface crack ratio and a retative humidity ratio in the case of clay.In the field,the volumetric water content,and the suction as well as the runoff were monitored for an embankment constructed with lime/cement treated soils.It appeared that using precipitation data only did not allow a correct description of the variations of volumetric water content and suction inside the soils,the consideration of water evaporation being essential.It was possible to use a correlation between precipiration and runoff.The hydraulic conductivity was found to be a key parameter controlling the variations of volumetric water content and suction.For the numerical modelling,a fully coupled thermohydraulic model was developed,allowing analyzing the changes in temperature,volumetric water content and suction of soil,with the upper boundary conditions at the interface between soil and atmosphere determined using meteorological data.Comparison between simulations and measurements showed the performance of such numerical approach.

关键词： Environmental chamber Soil water evaporation Suction-based evaporation model Embankment Field monitoring Numerical modeling

Numerical Study of Natural Convection in an Inclined Porous Cavity

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Fluid Dynamics & Materials Processing 2022年第5期18卷 1389-1397页

作者： Saad Adjal Sabiha Aklouche-Benouaguef Belkacem Zeghmati laboratoire des Transports Polyphasiques et Milieux Poreux LTPMPALGER16111ALGERIE laboratoire des Mathématiques et Physique des Systèmes LAMPSPerpignan66860France

Two-dimensional transient laminar natural convection in a square cavity containing a porous medium and inclined at an angle of 30°is investigated numerically.The vertical walls are differentially heated,and the horizontal walls are adiabatic.The effect of Rayleigh number on heat transfer and on the road to chaos is analyzed.The natural heat transfer and the Darcy Brinkman equations are solved by using a finite volume method and a Tri Diagonal Matrix Algorithm(TDMA).The results are obtained for a porosity equal to 0.45,a Darcy number and a Prandtl respectively equal to 10^(-3)and 0.71;they are analyzed in terms of streamlines,isotherms,phase portrait,attractors,and spectra amplitude as a function of the Rayleigh number.It is found that,as Rayleigh number increases,the natural convection changes from a steady state to a time-periodic state and finally to a chaotic condition.

关键词： Natural convection porous medium finite volumes chaos attractors

Influence of Auxiliary Equation on Wave Functions for Time-Dependent Pauli Equation in Presence of Aharonov-Bohm Effect

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Communications in Theoretical Physics 2009年第5期51卷 803-810页

作者： M.Maamache C.Lahoulou Y.Saadi laboratoire

为分离或连续的光谱特征值和单一的转变途径的不变的操作员方法被采用在 Aharonov Bohm 效果(AB ) 和外部分级的潜力的存在学习二维的时间依赖者泡利不相容原理方程。为旋转粒子，有磁场的问题是它在起源介绍奇特进波浪方程。物理动机... 详细信息

为分离或连续的光谱特征值和单一的转变途径的不变的操作员方法被采用在 Aharonov Bohm 效果(AB ) 和外部分级的潜力的存在学习二维的时间依赖者泡利不相容原理方程。为旋转粒子，有磁场的问题是它在起源介绍奇特进波浪方程。物理动机是由半径 R 之一代替零个半径流动试管，与磁场被限制到试管的表面的另外的条件，然后拿限制 R →0 在计算的结束。我们指不变的操作员必须包含步骤功能 θ(r R ) 。因而，这个问题变得更复杂。以便避免这个困难，我们由 ρ(t) R 代替半径 R，在 ρ(t) 是一个积极时间依赖者的地方，工作。然后，在计算的结束，我们拿限制 R →0。为不变的操作符光谱的质的性质为在 ρ(t) 满足的非线性的辅助方程出现的参数 C 的不同的值独立被描述，即， C > 0， C = 0，并且 C 0 ) 或连续(C ≤0 ) 。

关键词：辅助方程波函数时间依赖性时变注册商标变换方法波动方程阶跃函数

Redox and acetylation coordinate ABA-independent osmotic stress response

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Molecular Plant 2022年第4期15卷 583-585页

作者： Christophe Belin Jean-Philippe Reichheld laboratoire Génome et Développement des Plantes UniversitéPerpignan Via Domitia66860 PerpignanFrance laboratoire Génome et Développement des Plantes CNRS66860 PerpignanFrance

Osmotic stress caused by drought or high salt concentrations is a major threat that limits plant development and affect crop productivity.In the context of climate change,understanding the mechanisms by which plants perceive their environment to adapt to their development is a major question.A common feature of plants being exposed to osmotic stress is the accumulation of excessive reactive oxygen species(ROS)(Martinière et al.,2019).ROS can oxidatively damage biological molecules,such as nucleic acids,proteins,and lipids,but also play important signaling functions.To protect from ROS-induced oxidation,living organisms have developed a large panel of enzymatic and non-enzymatic systems to remove ROS and oxidized molecules.

关键词： functions. enzymatic coordinate

Numerical studies towards practical large-eddy simulation

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Journal of Thermal Science 2007年第4期16卷 328-336页

作者： J.Boudet J.Caro L.Shao E.Lév(?)que LMFA laboratoire

大旋涡的模拟开发和确认为狂暴的内部流动的改进模拟被介绍。数字方法根据二竞争标准被建议：数字质量(精确并且光谱特征) ，并且适应性到复杂配置。首先，方法在学术测试用例上被测试，以便与基本研究缩短。一致结果用能适应的有限体... 详细信息

大旋涡的模拟开发和确认为狂暴的内部流动的改进模拟被介绍。数字方法根据二竞争标准被建议：数字质量(精确并且光谱特征) ，并且适应性到复杂配置。首先，方法在学术测试用例上被测试，以便与基本研究缩短。一致结果用能适应的有限体积方法被获得，与更高的顺序移流流动，含蓄的格子过滤和鈥渓o w 花费鈥 ? 砍改进 Smagorinsky 模型。这分析特别地集中于吝啬的流动，变化，二点的关联和系列。而且，指数的平均是为在有确定的摇摆的复杂几何学的 LES 实现的一个有希望的工具，这被显示出。最后，方法的适应性被申请在 turbomachine 表明到片尖端清理流动的一个配置代表。

关键词：流量模型边界条件空间过滤模式大涡模拟

Small dissymmetry, yet large effects on the transport propertiesof electrolytes based on imide salts: Consequences on performancein Li-ion batteries

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Journal of Energy Chemistry 2022年第2期31卷 352-366页

作者： Joseph Chidiac Laure Timperman Mérièm Anouti laboratoire PCM2E Universitéde ToursParc de Grandmont37200 ToursFrance

To gain better insight into the influence of the anion size and symmetry on the transport properties and thermal stability of an electrolyte based on lithium(fluorosulfonyl)(trifluoromethanesulfonyl)-imide(FTFSI)salt,we performed the physical and electrochemical characterization of an electrolyte based on FTFSI incorporated in standard binary(3 EC/7 EMC)and ternary(EC/PC/3 DMC)alkylcarbonate mixtures.By applying the Jones-Dole-Kaminsky(JDK),Eyring and Arrhenius empirical models to the electrolyte viscosity we show that the activation enthalpy and entropy energy barriers(ΔH≠,ΔS≠)for viscous flow are between 12 and 15 kJ·mol^(-1).They are strongly dependent on the solvent nature and are significantly lower than their symmetric anions LiFSI and LiTFSI(19-20 kJ·mol^(-1))in the binary mixture.Furthermore,the hydrodynamic radius,rs,calculated by JDK,and the ionicity behavior illustrated by the Walden role,showed that the FTFSI anion is outside the solvation sphere(rs>0.6 nm)which is smaller in the case of an EC/EMC solvent base.In the 3 EC/7 EMC solvent mixture,LiFTFSI is less conductive than in the ternary mixture i.e.,σ_(max)=8.9 mS cm^(-1) at C_(max)=1.1 mol L^(-1) for 3 EC/7 EMC and,σ_(max)=10.5 mS cm^(-1) at max=0.7 mol L^(-1) for EC/PC/3 DMC,due to a strong solvation and a greater association of FTFSI ions in the binary solvent mixture.The thermal stability of FTFSI based electrolytes was determined by the shift of the evaporation temperature of the volatile solvents(DMC,EMC)in the presence of salt,towards the higher temperatures.This feature is visible on the thermograms obtained by DSC both with the liquid electrolyte and with charged LMO cathodes in presence of electrolytes.The consequences of these properties on the electrochemical behavior of a graphite(Gr)half-cell,a lithium metal(Li)anode and a manganese lithium oxide(LMO)cathode demonstrated on the one hand the formation of a thick solid electrolyte interphase(SEI)on graphite that consumed a significant amount of lithium i.e.,18%of total capacity of the f

关键词： LiFTFSI Electrolyte Viscosity Interface Li-ion battery

Methane-to-chemicals:a pathway to decarbonization

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National Science Review 2023年第9期10卷 56-71页

作者： Nikolai Nesterenko Izabel C.Medeiros-Costa Edwin B.Clatworthy Hugo Cruchade Stanislav V.Konnov Jean-Pierre Dath Jean-Pierre Gilson Svetlana Mintova Total Energies One Tech Belgium Zone Industrielle C laboratoire Catalyse et Spectrochimie(LCS) ENSICAENCNRSNormandie Université

The utilization of methane for chemical production,often considered as the future of petrochemistry,historically could not compete economically with conventional processes due to higher investment costs.Achieving sustainability and decarbonization of the downstream industry by integration with a methane-to-chemicals process may provide an opportunity to unlock the future for these technologies.Gas-to-chemicals is an efficient tool to boost the decarbonization potential of renewable energy.While the current implementation of carbon capture utilization and storage(CCUS) technologies is of great importance for industrial decarbonization,a shift to greener CO2-free processes and CO2utilization from external sources for manufacturing valuable goods is highly preferred.This review outlines potential options for how a methane-to-chemicals process could support decarbonization of the downstream industry.

关键词： methane chemicals pathways decarbonization