Toward a fully coupled THM mesoscopic modelling of the behaviour of concrete at high temperature

2019 ◽  
Author(s):  
D Dauti
Keyword(s):  
High Temperature ◽  
Mesoscopic Modelling ◽  
Fully Coupled

Fully Coupled Simulation of Oxygen and Heat Diffusion for (U,Pu)O2 Fuel in Both Fast-Breeder Reactor and Light-Water Reactor

2015 ◽  
Vol 1 (4) ◽  
Author(s):  
Wenzhong Zhou ◽  
Rong Liu
Keyword(s):  
High Temperature ◽  
Power Distribution ◽  
Heat Diffusion ◽  
Light Water Reactor ◽  
Fast Breeder Reactor ◽  
Light Water ◽  
Water Reactor ◽  
Ratio Change ◽  
Overall Performance ◽  
Fully Coupled

Oxygen redistribution with a high-temperature gradient is an important fuel performance concern in fast-breeder reactor (FBR) and light-water reactor (LWR) (U,Pu)O2 fuel under irradiation, and affects fuels properties, power distribution, and fuel overall performance. This paper studies the burnup dependent oxygen and heat diffusion behavior in a fully coupled way within (U,Pu)O2 FBR and LWR fuels. The temperature change shows relatively larger impact on oxygen to metal (O/M) ratio redistribution rather than O/M ratio change on temperature, whereas O/M ratio redistributions show different trends for FBR and LWR fuels due to their different deviations from the stoichiometry of oxygen under high-temperature environments.

scholarly journals A hygrothermo-mechanical model for wood: part A. Poroelastic formulation and validation with neutron imaging

Holzforschung ◽  
2015 ◽  
Vol 69 (7) ◽  
pp. 825-837 ◽  
Author(s):  
Saeed Abbasion ◽  
Jan Carmeliet ◽  
Marjan Sedighi Gilani ◽  
Peter Vontobel ◽  
Dominique Derome
Keyword(s):  
High Temperature ◽  
Moisture Content ◽  
Mechanical Model ◽  
Wood Sample ◽  
Industrial Process ◽  
Neutron Imaging ◽  
Correct Prediction ◽  
Environmental Loading ◽  
Wood Part ◽  
Fully Coupled

Abstract The correct prediction of the behavior of wood components undergoing environmental loading or industrial process requires that the hygrothermal and mechanical (HTM) behavior of wood is considered in a coupled manner. A fully coupled poromechanical approach is proposed and validated with neutron imaging measurements of moist wood specimens exposed to high temperature. This paper demonstrates that a coupled HTM approach adequately captures the variations of temperature, moisture content, and dimensions that result in a moist wood sample exposed to one-side heating.

scholarly journals A numerical simulation on coal seam gas recovery from high temperature reservoir

2020 ◽  
Vol 24 (6 Part B) ◽  
pp. 3971-3978
Author(s):  
Teng Teng ◽  
Xiao-Yan Zhu ◽  
Xiang-Yang Zhang ◽  
Peng-Fei Chen ◽  
Yu-Ming Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Coal Seam ◽  
Mechanical Model ◽  
Gas Flow ◽  
Gas Production ◽  
Coal Seam Gas ◽  
Production Time ◽  
Gas Recovery ◽  
Coal Deformation ◽  
Fully Coupled

The coal seam gas recovery in deep reservoirs often meets high temperature. The change of temperature can greatly influence gas sorption, and couples heat transfer with coal deformation and gas-flow. This paper modifies the conventional Langmuir adsorption equation into a non-isothermal adsorption equation with a set of experimental data. After then, a fully coupled thermo-hydro-mechanical model of coal deformation, gas-flow and heat transfer is established. By using a finite element approach of COMSOL multi-physics, a numerical simulation of coal seam gas recovery from high temperature reservoir is subsequently implemented. The results show that the gas pressure and temperature decrease with production time and increase with the distance from production well, the reservoir permeability decreases with production time due to the compaction of increasing effective stress to coal fracture network, the cumulative gas production increases with production time exponentially whereas the production efficiency decreases negative exponentially, that the gas production in earlier 10 years accounts for 80% of the total production in 30 years. Our fully coupled thermo-hydro-mechanical model can improve the current understanding of coal seam gas recovery from high temperature reservoirs.

Stability Analysis of a Fully Coupled Implicit Scheme for Inviscid Chemical Non-Equilibrium Flows

2016 ◽  
Vol 8 (6) ◽  
pp. 953-970 ◽  
Author(s):  
Yu Wang ◽  
Jinsheng Cai ◽  
Kun Qu
Keyword(s):  
High Temperature ◽  
Convergence Acceleration ◽  
Flow Conditions ◽  
Von Neumann ◽  
Space Step ◽  
The Stability ◽  
Recombination Reactions ◽  
Fully Coupled ◽  
Excellent Stability ◽  
Non Equilibrium

AbstractVon Neumann stability theory is applied to analyze the stability of a fully coupled implicit (FCI) scheme based on the lower-upper symmetric Gauss-Seidel (LU-SGS) method for inviscid chemical non-equilibrium flows. The FCI scheme shows excellent stability except the case of the flows involving strong recombination reactions, and can weaken or even eliminate the instability resulting from the stiffness problem, which occurs in the subsonic high-temperature region of the hypersonic flow field. In addition, when the full Jacobian of chemical source term is diagonalized, the stability of the FCI scheme relies heavily on the flow conditions. Especially in the case of high temperature and subsonic state, theCFLnumber satisfying the stability is very small. Moreover, we also consider the effect of the space step, and demonstrate that the stability of the FCI scheme with the diagonalized Jacobian can be improved by reducing the space step. Therefore, we propose an improved method on the grid distribution according to the flow conditions. Numerical tests validate sufficiently the foregoing analyses. Based on the improved grid, theCFLnumber can be quickly ramped up to large values for convergence acceleration.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

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