Effects of electric fields on the bending behavior of PZT-5H piezoelectric laminates

This paper investigates the bending behavior of piezoelectric laminates under combined mechanical and electrical loads. The laminates have a PZT-5H ceramic core sandwiched between two graphite/epoxy plates. Three-point bending tests and in situ acoustic emission measurements were conducted on the PZT-5H sandwich laminates with a sustained applied electric field. The results show that the PZT-5H core fractures first and then delaminaton occurs along the tensile stressed interface between the PZT ceramic and a graphite/epoxy layer. Finite element analysis was performed to analyze the stresses in the sandwich structure and the energy release rate for interface delamination under combined mechanical and electrical loads. Consequently, both the bending strength of the PZT core and the interface toughness were evaluated from the experimental data. Although the experimental data scatter widely, the electric field, either positive or negative, reduces the average fracture strength of the PZT core. The average interface toughness decreases on increasing the magnitude of a negative electric field, while it is increased by a positive electric field.