X. Gao et al., CONSTRAINT EFFECTS ON THE DUCTILE-BRITTLE TRANSITION IN SMALL-SCALE YIELDING, Journal of the mechanics and physics of solids, 44(8), 1996, pp. 1255
The effect of constraint on the ductile-brittle transition is investig
ated numerically under small scale yielding conditions in plane strain
. An elastic-viscoplastic constitutive relation for a porous plastic s
olid is used to model ductile fracture by the nucleation and subsequen
t growth of voids to coalescence. Two populations of second phase part
icles are represented, large inclusions with low strength, which resul
t in large voids near the crack tip at an early stage, and small secon
d phase particles, which require large strains before cavities nucleat
e. Adiabatic heating due to plastic dissipation and the resulting ther
mal softening are accounted for in the analyses. Cleavage is modeled i
n terms of attaining a temperature and strain rate-independent critica
l value of the maximum principal stress over a specified material regi
on. A characteristic length is associated with each failure mechanism;
the large inclusion spacing for ductile failure and size of the cleav
age region for brittle failure. The crack growth predictions are conse
quences of the constitutive characterization of the material, so that
the present study is free from ad hoc assumptions regarding appropriat
e crack growth criteria. The numerical results show that the extent of
cleavage fracture relative to ductile fracture is strongly controlled
by temperature and constraint. Fracture resistance curves are obtaine
d for a range of conditions. Copyright (C) 1996 Elsevier Science Ltd