An examination on the direct concentration approach to simulating moisture diffusion in a multi-material system

Liu, Dapeng; Wang, Jing; Liu, Ruiyang; Park, S.B.

doi:10.1016/j.microrel.2016.03.012

Cited by 20 publications

(6 citation statements)

References 16 publications

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“…Several previous studies handled these interfaces by ensuring the continuity of the solute hydrogen particles concentration for simplification purposes [7,14]. Liu et al [15] extended the Sievert's law to solidsolid interface, based on the mass-diffusion procedure of the Abaqus code [16]. The ratio between the solute concentration and the solubility is used to convey the conservation of chemical potential across interfaces.…”

Section: Introductionmentioning

confidence: 99%

Influence of interface conditions on hydrogen transport studies

Hodille¹,

Mougenot²,

Charles³

et al. 2021

Nucl. Fusion

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This work investigates the influence of hydrogen chemical potential continuity across solid material interfaces. The implementation of the mathematical model in FESTIM is verified using the Method of Exact Solutions (MES) and the Method of Manufactured Solutions (MMS) in 1D, 2D, with complex material properties and inhomogeneous temperature fields. A comparison test between FESTIM, TMAP7 and Abaqus codes is also performed and the codes show good agreement. The chemical potential continuity condition has an impact up to 40% on the outgassing particle flux on 4 mm composite slabs (W/Cu and Cu/EUROFER) compared to mobile concentration continuity. A method for rapid identification of materials properties from outgassing flux measurements is given. The influence of chemical potential conservation on monoblock inventory is then studied. It is shown that, for the 1D and 2D ITER divertor monobolocks cases, discrepancies only start to appear after approximately 5 × 10 6 s of full power.

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Section: Introductionmentioning

confidence: 99%

Influence of interface conditions on hydrogen transport studies

Hodille¹,

Mougenot²,

Charles³

et al. 2021

Nucl. Fusion

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“…In macroscopic rate equation (RE) models of HI transport in plasma facing components with multi-materials, different models exists to tackle the transfer across the interface. For instance, one can use the continuity of the concentration of mobile (interstitial) HI or the continuity of the chemical potential [45][46][47][48] at the interface. The latter model is based on thermodynamics and is the most physical one.…”

Section: Thermodynamic Considerationsmentioning

confidence: 99%

Molecular dynamics study of hydrogen isotopes at the Be/BeO interface

Hodille¹,

Byggmästar²,

Ferro³

et al. 2022

J. Phys.: Condens. Matter

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Molecular dynamics simulations are used to investigate the behaviour of D atoms at two interfaces between Beryllium (Be) and Beryllium oxide (BeO). After relaxation of the simulation cell, there are (i) localised defects at the interface and (ii) a hexagonal misfit dislocation network creating a succession of compressed and expanded area from each side of the interface. The simulations between 750 K and 1500 K for tens to hundreds of nanoseconds show that both interfaces act as trapping sites for D atoms. The simulations also show that D atoms tend to migrate in the material where the H solubility is the highest as predicted by thermodynamics. However, the simulations also shows that there are additional kinetic barriers (D trapping sites, D2 formation/dissociation in BeO) that slow down the path to equilibrium. These additional kinetic barriers may influence the fuel retention and permeation in Be materials.

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“…Due to this discontinuity, it is not possible to solve for the concentrations using traditional finite element method. Upon normalizing the concentrations with their respective solubilities, the discontinuity at the interface is removed and φ becomes continuous according to the Nernst partition rule [47]. Figure 7 represents the normalized concentration approach, where, The boundary conditions for the 2D micromechanical model are:…”

Section: Governing Equations and Input Propertiesmentioning

confidence: 99%

Fiber Packing and Morphology Driven Moisture Diffusion Mechanics in Reinforced Composites

Subramaniyan,

Imam,

Prabhakar

2021

Preprint

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Fiber reinforced polymer composite (FRPC) materials are extensively used in lightweight applications due to their high specific strength and other favorable properties including enhanced endurance and corrosion resistance. However, these materials are inevitably exposed to moisture, which is known to drastically reduce their mechanical properties caused by moisture absorption and often accompanied with plasticization, weight gain, hygrothermal swelling, and de-bonding between fiber and matrix. Hence, it is vital to understand moisture diffusion mechanics into FRPCs. The presence of fibers, especially impermeable like Carbon fibers, introduce tortuous moisture diffusion pathways through polymer matrix. In this paper, we elucidate the impact of fiber packing and morphology on moisture diffusion in FRPC materials. Computational models are developed within a finite element framework to evaluate moisture kinetics in impermeable FRPCs. We introduce a tortuosity factor for measuring the extent of deviation in moisture diffusion pathways due to impermeable fiber reinforcements. Two-dimensional micromechanical models are analyzed with varying fiber volume fractions, spatial distributions and morphology to elucidate the influence of internal micromechanical fiber architectures on tortuous diffusion pathways and corresponding diffusivities. Finally, a relationship between tortuosity and diffusivity is established such that diffusivity can be calculated using tortuosity for a given micro-architecture. Tortuosity can be easily calculated for a given architecture by solving steady state diffusion governing equations, whereas time-dependent transient diffusion equations need to be solved for calculating moisture diffusivity. Hence, tortuosity, instead of diffusivity, can be used in future composites designs, multi-scale analyses, and optimization for enabling robust structures in extreme moisture environments.

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An examination on the direct concentration approach to simulating moisture diffusion in a multi-material system

Cited by 20 publications

References 16 publications

Influence of interface conditions on hydrogen transport studies

Influence of interface conditions on hydrogen transport studies

Molecular dynamics study of hydrogen isotopes at the Be/BeO interface

Fiber Packing and Morphology Driven Moisture Diffusion Mechanics in Reinforced Composites

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