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   [게시 종료]

▣ Title: Multiscale Modeling of Dislocation Dynamics

▣ Speaker: Jaehyun Cho

▣ Affiliation: NASA  Ames Research Center

▣ Date: 2021. 5. 28.(Fri) 13:00

▣ Venue: Online(Zoom)

▣ Host: Prof. Keonwook Kang

▣ Abstract

Dislocation dynamics including nucleation, interactions with other defects and formation of microstructure is key to understand mechanical properties of metals. Developing tools to appropriately account for these behaviors is therefore desirable. In turn, dislocations behaviors at several scales from atomistic to mesoscopic levels must be captured, and it requires the development and use of multiscale models. This presentation is concerned with the two multiscale methods and their usages. The first multiscale method named three dimensional Coupled Atomistic/Discrete-Dislocation (CADD-3d) seamlessly integrates dislocation dynamics at nano- and micro-scales within a single computational framework [1,2,3]. Molecular dynamics is to be used in local domains where dislocations nucleate, i.e. where an atomistic resolution is essential. Outside of such regions, the evolving plasticity (network of dislocations) is described by DDD. This CADD-3d is applied to study Frank-Read source in an aluminum alloy, and provides insights on the mechanisms of solid-solution strengthening and grain-hardening effects at the nano and micro scales. The second multiscale method is Discrete Dislocation Dynamics (DDD with the ParaDiS code). Accuracy of this “hierarchical” multiscale method relies on dislocation parameters calibrated to match the atomistic system and appropriate topological changes [4,5]. Due to its simplicity and flexibility, the DDD method can be used to study plasticity problems evolving with a lots of dislocations at a low computational cost, and can be easily extended to account dislocation dynamics in a complex system, respectively. As examples, we apply the DDD method to show formation of the dislocation microstructures (cellular structures) and extend to study plasticity of polycrystals [6].

[1] Dewald, M., Curtin, W.A., 2006. Analysis and minimization of dislocation interactions with atomistic/continuum interfaces. Modelling and Simulation inMaterials Science and Engineering 14, 497.'

[2] Anciaux, G., Junge, T., Hodapp, M., Cho, J., Molinari, J.F., Curtin, W.A. 2018. The coupled atomistic/discrete-dislocation method in 3d Part I: Concept and algorithms. Journal of the Mechanics 

and Physics of Solids 118, 152-171

[3] Cho, J., Molinari, J.F., Anciaux, G. 2018. The coupled atomistic/discrete-dislocation method in 3d. Part III: dynamics of hybrid dislocations, Journal of the Mechanics and Physics of Solids 118, 1-14

[4] Arsenlis, A., Cai, W, Bulatov, V. V., Rhee, M., Tang, M., Oppelstrup, T., Hiratani, M., Hommes, G., Pierce, T. G. 2007. "Enabling Strain Hardening Simulations with Dislocation Dynamics", 

    Modelling and Simulation in Materials Science and Engineering, 15, 553.

[5] Cho, J., Molinari, J.F., Anciaux, G. 2018. Mobility law of dislocations with several character angles and temperatures in FCC aluminum, International Journal of Plasticity 90, 66-75

[6] Cho, J., Crone, J.C., Arsenlis, A., Aubry, S. 2020. Dislocation dynamics in polycrystalline materials, Modelling and Simulation in Materials Science and Engineering 28 (3), 035009

Zoom: https://yonsei.zoom.us/j/87037815386?pwd=WXlzUE1PSkVReTluUVNtSklYVXo2dz09

회의 ID: 870 3781 5386
암호: 781964