Indentation-Induced Interface Decohesion Between a Piezoelectric Film and an Elastic Substrate

Finite element analysis was used to study the indentation-induced decohesion of the weakly bonded interface between a piezoelectric film of PZT-4 and an elastic substrate. A linear traction-separation law was used to model the interface behavior. The finite element results showed that interface decohesion initiates and grows during the loading process, and the unloading process has no effect on enlarging interfacial failure. The critical indentation depth for the onset of the interface decohesion during indentation increases with increasing the work of adhesion, while it decreases with increasing the interface stiffness and interface strength for the same work of adhesion. Increasing the thickness of the piezoelectric film and the elastic modulus of the substrate can retard the occurrence of the interface decohesion, and large indentation depth is needed to cause the initiation and propagation of the interface decohesion. Electric field can either accelerate or suppress the indentation-induced interface decohesion, depending on the direction of the electric field.