Piezoelectric composite actuators with FGM
functionally graded microstructure

Piezoelectric materials can exhibit a very fast displacement under relatively large appled electric field, but its strain remains still modest. By laminating identical two piezoelectric layers, one can design a bimorph actuator for bending mode where the electric polartiy of the top and bottom layers are mirror symmetric with respect to the mid-plane. This bimorph actuator for bending mode has been used for several applications, but its fatigue life remains to be short to intermediate, due to large shear stresss at the interface. To overcome this, we have designed a FGM bimorph piezo composite plate where the top and bottom plate are composed of multi-layer with their electroelastic properties are graded toward the mid-plane. This design gives us the stress fiel of smaller gamnitutde than that in the standard bimorph, yet provding us with larger bending displacement. We have involved in construction of hierarchical modeling, design of actuation displacement measurement set up and processing of several types of FGM piezo-laminates.