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As the dimensions of a structure are decreased towards the nanometer scale, the mechanical response to loading deviates from what is observed macroscopically. This is due to a change in material properties stemming from the relative increase in number of surface atoms as compared to bulk atoms. Surface atoms lack some of their neighboring atoms, leading to a reorganization of the electron clouds and, thereby, to energy states differing from those of bulk atoms. Also at a grain boundary the atomic lattice is disturbed, and bonds between atoms in regions of different lattice orientations must be formed. The energy states of atoms close to such a disorder differ from the states for bulk atoms. All disturbed atomic regions are prone to dislocation interactions under mechanical loading. This should be especially true in the vicinity of both a surface and a grain boundary. Here we investigate tensile loading of nanosized Cu-beams, of length 100a0, with a0 denoting the lattice parameter, and with square cross sections with side length between 6a0 and 48a0 by molecular dynamic simulation. A grain boundary, normal to the loading direction, is introduced at the center of the beam to create two grains. The grain boundaries investigated are between the lattice orientations ,  and , i.e. in all three combinations. Under loading dislocations are generated from the grain boundaries and extend into the weakest of the two grains. No dislocations pass a grain boundary or extend into both grains. It is also found that the yield stress decreases in the presence of a grain boundary as compared to a single grain beam. The stress-stain curves themselves are ragged and a correlation between the development of the dislocation density and the raggedness is observed.
|Number of pages||2|
|Publication status||Published - 2019 Aug 5|
|Event||The fourth International Symposium on Atomistic and Multiscale Modeling of Mechanics and Multiphysics - Friedrich-Alexander Universität , Erlangen-Nürnberg (FAU), Germany|
Duration: 2019 Aug 5 → 2019 Aug 7
Conference number: 4
|Conference||The fourth International Symposium on Atomistic and Multiscale Modeling of Mechanics and Multiphysics|
|Period||2019/08/05 → 2019/08/07|
Subject classification (UKÄ)
- Applied Mechanics
- 1 Active
Modelling mechanical properties at nanoscale by molecular dynamics
Ahadi, A., Melin, S. & Hansson, P.
2017/02/01 → …