The 9th International Conference on Multiscale Materials Modeling

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Symposium

C. Crystal Plasticity: From Electrons to Dislocation Microstructure

[SY-C3] Symposium C-3

Tue. Oct 30, 2018 9:45 AM - 11:00 AM Room1

Chair: Francois Willaime(DEN-Departement des Materiaux pour le Nucleaire, CEA, Universite Paris-Saclay, France)

[SY-C3] Discrete dislocation plasticity modelling of hydrogen dislocation interactions in micro-cantilevers

○Haiyang Yu1, Alan Cocks2, Ed Tarleton1 (1.Dept. of Materials, Univ. of Oxford, UK, 2.Dept. of Engineering, Univ. of Oxford, UK)

One of the most widely accepted theories for hydrogen embrittlement is the hydrogen enhanced localized plasticity (HELP) mechanism which claims hydrogen enhances dislocation activity locally. Experimental evidence for this mechanism has been reported across different scales. Simulations however are mainly limited to the atomistic scale, and continuum scale. Direct simulation of hydrogen dislocation interactions in micromechanical tests is rarely simulated, due to the fact that this scale is beyond the computational capacity of most atomistic calculations and beyond the resolution of most continuum approaches. Discrete dislocation plasticity (DDP) is an ideal technique to bridge the gap in multiscale modelling of hydrogen embrittlement. Recently, a framework which incorporates hydrogen effects in a discrete dislocation simulation was derived by Gu and El-Awady [1] enabling direct investigation of hydrogen dislocation interactions at the microscale. We have implemented this formulation in a new code called EasyDD, a GPU accelerated version of DDLab coupled with FEM, and performed virtual micromechanical tests with mixed boundary conditions. We have simulated the behaviour of hydrogen charged micro-cantilevers and included the hydrogen induced tractions on the free surfaces. Hydrogen is observed to shield dislocation mutual interactions and to enhance dislocation generation, the combination of these effects leads to global softening and local stress concentrations promoting failure; consistent with the HELP mechanism. To the best of our knowledge, this work is the first to reveal hydrogen dislocation interactions at the discrete dislocation scale in finite volumes, acting as an essential bridge in multiscale modelling.



[1] Gu, Y., & El-Awady, J. A. (2018). Journal of the Mechanics and Physics of Solids, 112, 491-507.