Reliability Analysis And Geometry Optimization Of Multilayer Piezoelectric Actuator

In recent years, multilayer piezoelectric ceramic has been widely used in micro-electromechanics,micro-electronics and smart structures, and is generally served as actuators in smart structures. However, piezoelectric ceramics are easy to be fractured as a kind of brittle material. And multilayer piezoelectric structures especially multilayer piezoelectric actuators often failured from the edge of internal electrodes. Therefore, it is important to study the strength and functional reliability of them. And what follows is the work had been done in this thesis:1. The region around the electrode edge of the multilayer piezoelectric actuator used in aero field is studied in detail. The model of this structure is established and calculated by commercial software ABAQUS. And it is meshed densely for achieving the distribution of the electric and stress fields in the small region. Results of this simulation present the distribution of electric, strain and stress fields in the region around the electrode edge of the multilayer piezoelectric actuator. Furthermore, the concentration phenomena of the electric and stress fields are analyzed and discussed. And the changes of stress along and vertical to the electrode are given. 2. For relaxation of the stress concentration in the region around the electrode edge of the multilayer piezoelectric actuator, a geometry optimized model is brought forward, by changing the interfacial crack into an angle. Some optimized models with different angles are simulated to get the stress distribution. Then the relation between the maximum value of the stress and the angle, as well as the range of the optimum angle is given. In contrast with the original model, the optimized model can effectively improve the distribution of the electric and stress fields and achieve the goal of decreasing the stress concentration. 3. Some representative interface and cracking models of multilayer piezoceramics-epoxy resin structure are simulated by FEA and the distributions of the stress around the interfacial crack and electrode crack are discussed. Results show that the free unbonded surfaces of piezoceramics and epoxy resin can not be simply treated as free boundary condition during the process of model establishing.