  A new gradient-based formulation for predicting fracture in elastic-plastic
solids is presented. Damage is captured by means of a phase field model that
considers both the elastic and plastic works as driving forces for fracture.
Material deformation is characterised by a mechanism-based strain gradient
constitutive model. This non-local plastic-damage formulation is numerically
implemented and used to simulate fracture in several paradigmatic boundary
value problems. The case studies aim at shedding light into the role of the
plastic and fracture length scales. It is found that the role of plastic strain
gradients is two-fold. When dealing with sharp defects like cracks, plastic
strain gradients elevate local stresses and facilitate fracture. However, in
the presence of non-sharp defects failure is driven by the localisation of
plastic flow, which is delayed due to the additional work hardening introduced
by plastic strain gradients.
