  We develop a model for the gliding of dislocations and plasticity in solid
He-4. This model takes into account the Peierls barrier, multiplication and
interaction of dislocations, as well as classical thermally and mechanically
activated processes leading to dislocation glide. We specifically examine the
dc stress-strain curve and how it is affected by temperature, strain rate, and
dislocation density. As a function of temperature and shear strain, we observe
plastic deformation and discuss how this may be related to the experimental
observation of elastic anomalies in solid hcp He-4 that have been discussed in
connection with the possibility of supersolidity or giant plasticity. Our
theory gives several predictions for the dc stress strain curves, for example,
the yield point and the change in the work-hardening rate and plastic
dissipation peak, that can be compared directly to constant strain rate
experiments and thus provide bounds on model parameters.

Materials Science