Plastic deformation in two-dimensional monophase and composite materia
ls is studied using a discrete dislocation dynamics method. In this me
thod, dislocations are represented by line defects in a linear elastic
medium, and their interactions with boundaries or second-phase elasti
c particles are incorporated through a complementary finite element so
lution. The formulation includes a set of simple constitutive rules to
model the lattice resistance to dislocation glide, as well as the gen
eration, annihilation and pinning of dislocations at point obstacles.
The focus is on the predicted strain hardening of these materials when
only a single slip system is active. When the particle morphology is
such as to require geometrically necessary dislocations, hardening in
the composite materials exhibits a distinct size effect. This size eff
ect is weaker than that predicted by simple analytical estimates based
on geometrically necessary dislocations.