In this paper a new elastic-plastic strain decomposition method is proposed based on Molecule Dynamics(MD) simulation for metallic structures. First the motion traces of atoms are decomposed into structural deformation component and thermal vibration, then the computational method and approximate formulae on the structural deformation are given. To the current configuration of the structure the continuous deformation functions are constructed based on the composition pattern of BCC|FCC cells and tetrahedral elements supported by 4-atoms, and the algorithm of deformation gradient is shown. And by using the atomic-continuum coupled model the calculation formulae of the stress fields and elasticity tensor are developed. And then, the micro-defect forms generated by overlarge loading inside materials are analyzed, and classified into dislocations, stacking faults, twin boundaries, grain boundaries and vacancies et al. The constrained equations of rigid body motion satisfied for the stacking faults and twin boundaries during the elastic unloading process are derived, then the elastic unloading algorithm of current configuration is created by making use of minimum potential energy principle. Further, the entire elastic-plastic strain decomposition algorithm based on MD simulation is proposed. Finally, the numerical results for the tension of single crystal Cu nanowire are shown. It shows that the elastic-plastic strain decomposition method in this paper is reasonable.
The elastic-plastic decomposition method based on MD simulation presented above can be applied into the multi-scales analysis coupled with multiple models for mechanic behaviors of materials and their structures.
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