Design of Multi-phase Piezoelectric Actuators

A new multi-objective topology optimization method is proposed in this study for systematic design of multi-phase piezoelectric actuators. The actuator under consideration is composed of a compliant host structure equipped with piezoelectric elements, where the host structure serves as a compliant amplifier to enlarge the small stroke output generated by the actuation force of piezoelectric materials. In the context of optimal design of smart actuators, however, most up-to-date approaches are either to optimize only the host passive structure with pre-determined piezoelectric stacks or to optimize the piezoelectric actuator with pre-known structure, both of which restricts the overall performance of multi-material actuators. To capture the inherent multi-criteria characteristic of compliant actuators, this study proposes a new multi-objective topology optimization formulation to consider both the structural stiffness and mechanical flexibility of the actuation system via the physical programming. A SIMP-based interpolation scheme is applied to describe practical material properties of any points in the orthotropic design domain. The design problem of the actuator is thus transformed to a numerical process of distributing multiple materials iteratively in the design domain until both the host structure and piezoelectric material elements are optimized. Two typical numerical examples are applied to demonstrate the effectiveness of this method in the design of in-plane actuation devices.