Abstract :
utilizing the eigenstram formulation and Cauchy‘s residue theorem. a unified explicit
expression for the electroelastic fields inside a flat ellipsoidal crack embedded in an infinite piezoelectric
solid subjected to electromechanical loads is presented. In particular. an explicit expression
is obtained for a penny-shaped crack in a transversely isotropic piezoelectric medium. Three loading
cases. a simple tension, a pure shear, and an electric displacement, have been considered to examine
the behavior of penny-shaped cracking. The results show that the applied shear stress does not
couple with the electric displacement. unlike the simple tension case. Furthermore, the change of
potential energy due to the presence of the crack is evaluated. With this result and based on the
Griffith theory, the fracture stresses and critical electric displacement are presented in closed forms.
Explicit expressions for stress and electric displacement intensity factors are also given. It is verified
that the resulting fracture stresses and stress intensity factors can be reduced to those for uncoupled
hnear elastic fracture mechanics when pieroelectric coupling is absent and the material is isotropic.
c 1997 Elsevier Science Ltd
