Frank-Read位错源的细观级模拟

MESO-SCALE SIMULATION OF FRANK-READ DISLOCATION SOURCES

为了在细观尺度上更好地模拟Frank-Read(FR)位错源的演化,本文改进了三维(3D)离散位错动力学模型中相邻位错段间作用力计算方法和位错线的离散化方法.模拟结果表明,所改进的位错动力学模型能更准确地模拟不同初始长度的FR位错源的临界剪切应力和临界组态.并且加载应力越大,FR位错源形成的位错环越小,并逐渐接近不考虑位错段间相互作用力时所形成的位错环.在相同加载应力时,Peierls应力越大,形成的位错环也越大.阻尼系数只影响位错环形成的时间,而不影响形成的大小.位错的这种非线性演化方式,是位错段间存在相互作用力引起的.

The computation method of the interaction force between adjacent dislocation segments and the discretization method of the dislocation line in the 3D model of discrete dislocation dynamics were improved in order to simulate the evolution of Frank Read （FR） dislocation source on the meso-scale. The simulation results show that the improved model can more accurately simulate the critical shear stresses and dislocation configurations of the FR dislocation sources with different initial lengths. Moreover, the smaller dislocation loop is formed by FR dislocation source when larger stress loaded, and approaches the dislocation loop formed without considering the interactions among the dislocation segments. Under the same loaded stress, the larger loop is formed with increasing the Peierls stress. However, the drag coefficient only affects the formation time of the loop, but can not affect the loop size. This kind of nonlinear evolution of dislocation is caused by the interactions among the dislocation segments.