Design of a piezoelectric actuator and compliant mechanism combination for maximum energy efficiency

The combined optimization of a compliant mechanism and a piezoelectric stack actuator for maximum energy conversion efficiency is considered. The analysis assumes all components to be free from dissipation and that the piezoelectric stack actuator is driven by an ideal sinusoidal voltage source. The energy conversion efficiency is defined as the ratio of the output mechanical energy to the input electric energy. Using linear two-port models, an analytical expression for the maximum energy conversion efficiency is derived. It is shown that the optimization of the piezoelectric stack actuator can be decoupled from the topology optimization of the compliant mechanism. Computational verification of the analytical results is presented for two ground structures modeled using frame elements. The trade-off between displacement amplification and maximization of the energy conversion efficiency is examined.