(Paper to appear in Bollettino della Unione Matematica Italiana - Bulletin of the Italian Mathematical Union)

Luc Tartar and Amit Acharya

Global existence and uniqueness results for a quasilinear system of partial differential equations in one space dimension and time representing the transport of dislocation density are obtained. Stationary solutions of the system are also studied, and an infinite dimensional class of equilibria is derived. These time (in)dependent solutions include both periodic and aperiodic spatial distributions of smooth fronts of plastic distortion representing dislocation twist boundary microstructure. Dominated by hyperbolic transport-like features and at the same time containing a large class of equilibria, our system differs qualitatively from regularized systems of hyperbolic conservation laws and neither does it fit into a gradient flow structure.

The main idea is the following: a most natural mathematical setup for considering the motion of the void-solid interface of an expanding void is that of the traveling wave. Thus, a theory for macroscopic damage evolution may be suspected as being a homogenized version of basic theory that has such wave phenomena as an essential ingredient. This paper is a first step in probing such questions.