Topology optimization and detailed finite element modeling of piezoelectric actuators: Effect of external loads and detail geometry on actuator output

Compliant mechanical amplifiers are often used to amplify small motions such as those of PZT actuators, since they do not incur displacement losses that frequently occur in pin-jointed mechanisms. Their optimal design is key to maximizing actuator performance. Our previous work was focused on developing a topology optimization methodology wherein the size of the design domain and the location of the PZT actuator were pre-defined. The resultant solution was one that maximized stroke amplification. In this paper we study the effects of stack and structural properties on resultant topology and output stroke with focus on quantitative performance for practical application. The motivating example is an actuator-design problem where ±400 μm stroke and 45 N force is required. The problem is solved using topology design methodology and the results obtained are verified using finite element analysis. We demonstrate that magnitude of output displacement is extremely sensitive to preload on the compliant mechanical amplifier, amplifier and actuator material, topology interpretation while converting it into a solid model, and magnitude of applied voltage. We discuss effects of asymmetric placement of the PZT stack, multiple stacks, and increased stack length on resultant displacement.