We discuss a novel mesoscopic tensorial model (MTM) of crystal plasticity which allows one to capture in a geometrically precise way the role of crystallographically-specific lattice invariant shears. It represents a crystal as a collection of deforming elastic elements whose nonlinear elastic response is governed by globally periodic potential defined in the space of metric tensors. The ensuing Landau-type model with infinite number of equivalent energy wells effectively views a plastically deformed crystal as a mixtures of equivalent “phases”. Plastic yield is interpreted as an escape from the reference energy well, and plastic ‘‘mechanisms’’ are linked to low-barrier valleys of the energy landscape. Rate-independent dissipation emerges due to the well-switching events describing elementary plastic slips. While the MTM approach is formulated in terms of macroscopically measurable quantities (stress and strain), it can handle the short range interactions, involved in the dislocation nucleation and in the interaction of dislocations with various obstacles, without introducing ad-hoc relations.
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