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Nano-scale Remodeling at the Propagating Crack Tip for Multi-scale Analysis of Crack Propagation

Soon Wan Chung* and Seung Jo Kim

School of Mechanical & Aerospace Engineering, Seoul National University,
Seoul 151-742 Korea, Republic of (South)

This is an abstract for a presentation given at the
11th Foresight Conference on Molecular Nanotechnology

 

In this paper, the computational domain for multi-scale analysis is remodeled in accordance with the crack propagation of brittle material to minimize the computational cost by nano-scale atomic simulation. The multi-scale methodologies such as MAAD (Macroscopic, Atomistic, Ab initio Dynamics) [1] and FE/MD hybrid modeling [2] predict the region where the crack will propagate and use many atoms or electrons at the candidate region from the beginning of computation. Therefore, even the atoms or electrons which are off a crack tip are involved in MD or QM simulation. In this study, the nano-scale atomic structure is minimally used at a crack tip and a new multi-scale modeling, that is to say, atomic structure, handshake region and finite element meshes, will be made according to crack propagation. Although the computation increases due to the remodeling around the crack tip, this remodeling has the advantage of reducing the high computational cost for MD or QM simulation. To transform a numerical model into other model with different scale, the total Hamiltonians of two numerical models will be made to be equal. The molecular dynamics is simulated by use of the many-body interatomic potentials. The continuum model is implemented by the general 4-node and 8-node continuum element. The handshaking Hamiltonian combines the interatomic potential at MD region and the elastic strain energy potential at the continuum region. The computation in this study is carried out in the PEGASUS cluster system which consists of 400 Intel Xeon CPUs. A highly efficient space-time multi-resolution algorithm [3] for massively parallel computers will be utilized. Also, the minimal domain for the nano-scale modeling will be investigated by comparing the results by changing the size of nano-scale modeling.

References

[1] F.F. Abraham, J.Q. Broughton, N. Bernstein and E. Kaxiras, "Spanning the continuum to quantum length scales in a dynamic simulation of brittle fracture," Europhysics Letters, 44(6), 1998, 783-787.
[2] H. Rafii-Tabar, L. Hua and M. Cross, "A multi-scale atomistic-continuum modelling of crack propagation in a two-dimensional macroscopic plate," J. Phys.: Condens. Matter 10, 1998, 2375-2387.
[3] A. Nakano, R.K. Kalia and P. Vashishta, "Scalable molecular-dynamics, visualization, and data-management algorithms for materials simulations," Computing in Science & Eng., 1(5), 1999, 39-47.


*Corresponding Address:
Soon Wan Chung
School of Mechanical & Aerospace Engineering
Seoul National University
San 56-1, Shinlim-dong, Kwanak-ku
Seoul 151-742 Korea, Republic of (South)
Phone: +822-880-7389 Fax: +822-880-1918
Email: swchung@aeroguy.snu.ac.kr



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