Plastic deformation of single crystals is carried out by large number of dislocations. Dislocation theory enhanced by experimental tools such as transmission electron microscopy (TEM) has made significant advancements in understanding the plastic behavior of crystalline materials. However, due to the multiplicity and complexity of the dislocation mechanisms involved, there exists a huge gap between the properties of individual dislocations and unit dislocation mechanisms at the microscopic scale and the material behavior at the macroscopic scale. To translate the fundamental understanding of dislocation mechanisms into a quantitative physical theory for crystal plasticity, a new means of tracking the dislocation motion and interaction over large time and space evolution is needed. Three dimensional dislocation-dynamics (DD) simulation is aimed at developing a numerical tool for crystal plasticity. It directly simulates the dynamic, collective behavior of individual dislocations and their interactions. It produces stress strain curves and other mechanical properties, and allow detailed analysis of the dislocation microstructure evolution. In a numerical implementation, dislocation lines are respresented by connected discrete line segments that move according to driving forces including dislocation line tension, dislocation interaction forces and external loading. The dislocation segments respond to these forces by making discrete movement according to a mobility function that is characteristic of the dislocation type and the specific material being simulated. The dislocation mobility can be extracted from experimental data, or calculated by atomisic simulations. And the mobility is one of the key inputs to a DD simulation. Another important consideration for DD simulations is dealing with close dislocation-dislocation interactions such as annihilation and junction formation and breaking. These close interactions can be very complex and usually require special treatment. An efficient way to deal with them is to use prescribed 'rules'. A bottleneck for DD simulation is the calculation of the elastic interactions between dislocations which is long range in nature. In order to perform DD simulations for realistic material plastic behavior, efficient algorithms must be developed to enable the simulation over reasonable time and space range with a large number of dislocations.
Maintained by Randolph Q. Hood