The interaction between a semi-infinite crack and a screw dislocation under
antiplane mechanical and in-plane electrical loading in a linear piezoelec
tric material is studied in the framework of linear elasticity theory. A st
raight dislocation with the Burgers vector normal to the isotropic basal pl
ane near a semi-infinite crack tip is considered. In addition to having a d
iscontinuous electric potential across the slip plane, the dislocation is s
ubjected to a line-force and a line-charge at the core. The explicit soluti
on for the model is derived by means of complex variable and conformal mapp
ing methods. The classical 1/root r singularity is observed for the stress,
electric displacement, and electric field at the crack tip. The force on a
screw dislocation due to the existence of a semi-infinite crack subjected
to external electromechanical loads is calculated. Also, the effect of the
screw dislocation with the line-force and line-charge at the core on the cr
ack-tip fields is observed through the field intensity factors and the crac
k extension force. [S0021-8936(00)01501-4].