  Crack initiation and propagation in elastic - perfectly plastic bodies is
studied in a phase-field or variational gradient damage formulation. A
rate-independent formulation that naturally couples elasticity, perfect
plasticity and fracture is presented, and used to study crack initiation in
notched specimens and crack propagation using a surfing boundary condition.
Both plane strain and plane stress are addressed. It is shown that in plane
strain, a plastic zone blunts the notch or crack tip which in turn inhibits
crack nucleation and propagation. Sufficient load causes the crack to nucleate
or unpin, but the crack does so with a finite jump. Therefore the propagation
is intermittent or jerky leaving behind a rough surface. In plane stress,
failure proceeds with an intense shear zone ahead of the notch or crack tip and
the fracture process is not complete.
