MOLECULAR DYNAMICS SIMULATION OF THE EFFECT OF VOID DEFECTS ON CRACK GROWTH OF SINGLE CRYSTAL MAGNESIUM UNDER TENSILE CONDITIONS

The numerical simulation along the C-axis stretching process of a single crystal magnesium model with preset cracks and void defects was carried out by molecular dynamics method,and the effect of void defects at different positions on crack propagation in single crystal magnesium was studied.The simulation results show that under the same characteristic size,the yield strength of the single crystal magnesium model is affected by the voids at different location.When the voids are located in the crack[101—0]direction,the yield strength of the model is the lowest.The void can alleviate the stress concentration of the crack in the void direction,and affect the twins growth rate of the crack.The twin growth rate near the void of the crack is relative slowly,and the twin growth rate is the slowest when the void is located at[101—0]direction.The voids have a little influence on the propagation direction of the crack.Generally,the crack extends in the tensile direction after combining with the voids,and the overall appearance is a more symmetrical cone expansion.But,when the voids are located in the crack[0001]direction,there is no obvious connection between the cracks and the voids.