关联参照模型和位错发射过程的分子动力学模拟

提出关联参照模型和随位错位置变化的柔性位移边界条件．提供了一个在固定位移边界条件下位错穿越边界的方法．应用三维分子动力学方法研究了体心立方（ＢＣＣ）金属晶体钼裂尖发射位错的力学行为．

THE CORRELATIVE REFERENCE MODEL AND THE MOLECULAR DYNAMICS SIMULATION OF THE DISLOCATION EMISSION

A correlative reference model for the computer simulation of the molecular dynamics is proposed in this paper. Supposing that there is an infinite elastic continuum with a single edge crack, its elastic constants, such as E, G,v , are the same as those of the simulated crystal. There is a correlation between the realistic sample and the reference model. Two requirements must be satisfied in the simulation, see Figs. 1a and 1b. (1) The atomic displacement in the region 2 in Fig.1a is determined by that of the corresponding region in Fig.1b. (2) Supposing that there are N T dislocations emitted from the crack tip, here N T=N 1 N 3 . The positions of the N 1 emitted dislocations in region 1 on Fig.1b are determined by the observation of atomic configuration in Fig.1a. Other N 3 positions of the N 3 dislocations in the continuum region 3 are determined by the dislocation pileup theory of micromechanics. Based on the correlative reference model, the flexible displacement boundary scheme is introduced naturally. By applying the flexible displacement boundary technique, the method of describing the dislocation penetrating through the border is provided. The effect of the dislocation pileup described by the micromechanics theory can be demonstrated. It overcomes the defect of the small size of simulated sample. Along z direction, the periodicity boundary scheme is applied. Because six layers of atomes are arranged along z direction, the atoms in z direction can move. The emitted dislocation from the crack tip is always in the form of particle dislocation.