Fatigue behaviour of multilayer piezoelectric actuators

Fatigue experiments of multilayer PZT actuators are presented, carried out under various electrical and mechanical loading conditions. Impedance measurements of cycled actuators are made to determine nondestructively their actual state of degradation. Some fracture surface examinations are described and occurring crack patterns are shown. For a detailed investigation of crack initiation and crack growth at electrode tips and interface layer model experiments with 2-layer samples are performed with in situ crack growth observations. Different crack types are found and possible crack growth mechanisms are suggested.