The gliding behavior of edge dislocation near a grain boundary(GB)in copper under pure shear stresses is simulated by using molecular dynamics(MD)method. Many-body potential incorporating the embedded atom method (EAM) isused. The critical shear stresses for a single disocation to pass across GB surface areobtained at values of σ_c=23MPa～68 MPa and 137 MPa～274 MPa for ∑=165 smallangle tilt GB at 300K and 20K, respectively. The first result agrees with the exper-imental yield stress σ_y(=42 MPa) quite well. It suggests that there might be one ofthe reasons of initial plastic yielding caused by single dislocation gliding across GB.In addition, there might be possibility to obtain yield strength from microscopic anal-ysis. Moreover, the experimental value of σ_y at low temperature is generally higherthan that at room temperature. So, these results are in conformity qualitatively withexperimental fact. On the other hand, the ∑=25 GB is too strong an obstacle tothe dislocation. In this case, a dislocation is able to pass across GB under relativelylow stress only when it is driven by other dislocations. This is taken to mean thatdislocation pile-up must be built up in front of this kind of GB, if this GB may takeeffect on the process of plastic deformation.
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