(Interactions) Materials, Environment, Mechanics (MEM)
The O.R. MEM is committed to better understand the interactions between the mechanical behavior of metallic materials and the environment, especially in the presence of hydrogen, responsible for embrittlement phenomena affecting the performance of structures in service. The main activity is centered on the development of numerical tools for finite element simulation, based essentially on the Abaqus software and the enrichment of specific user procedures.
It is a question of carrying out complex calculations, taking into account, in a completely coupled way
- the environment-assisted fracture (cohesive zones) ;
- thermo-elasto-(visco)plastic fields, at the component and/or polycrystal scale;
- hydrogen diffusion and trapping on different types of traps (dislocations, gaps….), of evolving density. This trapping can be instantaneous (called Oriani equilibrium) or transient, via the resolution of differential equations of chemical kinetics. The diffusion is assisted by mechanical fields (hydrostatic pressure).
- transient heat transfer.
The applications concern essentially the field of hydrogen transport/storage in materials subjected to gaseous loads under pressure and/or under high thermal stress (notably encountered in tokamaks). The tools developed may also be of interest to related problems such as stress corrosion.
Simulations with couplings
Simulation of a disk test
Calculation of the diffusion and trapping of hydrogen in the disc test, as a function of the pressurization rate. Estimation of the impact of mechanical field heterogeneity at the polycrystal scale.
Benannoune, S., Charles, Y., Mougenot, J., Gaspérini, M., & De Temmerman, G. (2020). Multidimensional finite-element simulations of the diffusion and trapping of hydrogen in plasma-facing components including thermal expansion. Physica Scripta, T171, 014011. http://doi.org/10.1088/1402-4896/ab4335
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Coupled thermo-chemo-mechanical simulation
Coupled thermo-chemo-mechanical simulation to estimate the impact of thermal expansion fields and induced residual stresses on hydrogen retention in ITER plasma components.
Benannoune, S., Charles, Y., Mougenot, J., Gaspérini, M., & De Temmerman, G. (2020). Multidimensional finite-element simulations of the diffusion and trapping of hydrogen in plasma-facing components including thermal expansion. Physica Scripta, T171, 014011. http://doi.org/10.1088/1402-4896/ab4335
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Machine learning
Recently, couplings with machine learning methods have been developed to calculate hydrogen retention under different plasma exposure conditions.
Estimation of tritium retention in ITER as a function of time, in a “full power” scenario.
Delaporte-Mathurin, R., Hodille, E., Mougenot, J., De Temmerman, G., Charles, Y., & Grisolia, C. (2020). Parametric study of hydrogenic inventory in the ITER divertor based on machine learning. Scientific Reports, 10(1), 1–12. http://doi.org/10.1038/s41598-020-74844-w
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Disc Test
From an experimental point of view, the disk test, which allows to characterize the sensitivity of metal sheets under hydrogen gas pressure, is used as a severe test coupling imposed pressure and plastic deformation. It also allows, with the help of microstructural investigations by electronic microscopy, to analyze the cracking and embrittlement mechanisms induced by hydrogen in a wide range of materials (iron, steel, titanium,…).
Exemple de fissuration transgranulaire dans titane alpha après essai de disque
Colloque Matériaux 2018
