Small scale nonlinear analysis of electrostrictive crack problems

The asymptotic problem of a semi-infinite crack in an electrostrictive ceramic under electric loading is analyzed. A universal relation between the stress intensity factor and the electric field intensity factor under small-scale nonlinear conditions is obtained for a conducting crack as well as for an insulating crack. It is shown that the surfaces of the conducting crack are closed except a small zone near the crack tip, whereas all the surfaces of the insulating crack remain open. Energy release rates due to self-similar crack extension as well as due to dissimilar crack extension are also discussed. The energy release rate for the insulating crack does not always have a negative value, in contrast to a linear dielectric theory. (C) 1999 Elsevier Science Ltd. All rights reserved.