Tuesday, 12 October 2004 - 9:15 AM

This presentation is part of : Graduate Student Competition

A Multi-scale Atomistic-continuum Approach Coupling Molecular Dynamics and Material Point Method

Nitin P. Daphalapurkar, Bo Wang, Hongbing Lu, Samit Roy, and Ranga Komanduri. Oklahoma State University, 218 Engineering North, Stillwater, OK 74078-5016

Failure in single crystal and polycrystalline materials usually involve processes such as dislocation, cleavage, macrocrack initiation and growth until final fracture. Multi-scale modeling is necessary to understand the mechanical behavior of materials from atomistic to continuum scales. Material Point Method (MPM) has been used for continuum simulation. Compared with the finite element method (FEM), MPM has the following advantages: (1) MPM has ability to handle large deformation in a more natural manner so that mesh lock-up present in FEM is avoided; (2) MPM can be easily coupled with Molecular Dynamics (MD) simulations because of using material particles similar to atoms used in MD instead of elements in FEM; (3) Parallel computation is more straightforward because of the use of structured grid that is consistent with parallel computing grids. In this paper, a computational approach coupling MD and MPM has been developed for the multi-scale atomistic-continuum simulation. A one-to-one correspondence of MD atoms and MPM particles with seamless coupling was used in the transition zone between MD and MPM regions. In MD computation, Tersoff-type, three-body potential was used to compute the interaction force between Si-Si atoms. The coupled MD/MPM simulations of uniaxial tension at multi-scale were conducted on silicon workmaterial. Stress and strain curves were obtained and the effect of strain rate on material properties was also investigated. This new computational method has potential for use in cases where a detailed atomic-level analysis is necessary in localized spatially separated regions whereas continuum mechanics is adequate in the rest of the material.

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