Electric-field induced interfacial cracking in multilayer electrostrictive actuators

Electric-field induced interfacial cracking in multilayer electrostrictive actuators is studied for two typical cases: (1) an interface crack lying between an electrode layer and ceramic matrix; and (2) an interface crack with one tip at an embedded electrode-edge. Based on the small-scale saturation solutions, a direct method is proposed to calculate the electric-field induced stress intensity factors that avoids calculating the stress field. The effectiveness of the direct method is demonstrated by comparing the results derived with the known numerical solutions. For either case, the explicit condition is given that prohibits interfacial crack growth by restricting the thickness of ceramic layers and the intensity of the applied electric field. Especially, the maximum stress intensity factor derived for the above case (2) is found to be significantly larger than that obtained in the existing works for the electrode-tip matrix cracks. This result agrees with the experimental fact that interfacial cracking is the dominant failure mechanism in electrostrictive multilayer devices. Hence, the reliability design should be based on the conditions that prohibit interfacial cracking. (C) 1998 Elsevier Science Ltd. All rights reserved.