Kinetics of glide in crystalline materials
Much is known about the motion of dislocations in the framework of linear elasticity, but the crystalline nature of materials is usually not taken into account. On the other hand, this feature is important in order to determine the plastic behaviour of the material, since it is well known that dislocations can only glide on crystallographically determined closest-packed planes.
We address this issue in our work, restricting attention to screw dislocations in anti-plane shear deformations.
First we devise a general framework to deal with dislocations in elastic materials, and use a configurational balance to define the force acting on a dislocation, a concept generalizing the classical Peach-Koehler force. Then we introduce a maximum dissipation criterion which selects uniquely the plane of motion of a screw dislocation. This allows to describe completely the behaviour of a single defect in an elastic material, giving an energetical explanation of experimentally observed phenomena, such as cross slip and fine cross slip.
Article: P. Cermelli and M.E. Gurtin, ``The motion of screw dislocations in materials undergoing anti-plane shear: glide, cross-slip, fine cross-slip'' to appear on Arch. Rat. Mech. Anal., 1999.