Structural Design and Frequency Tuning of Piezoelectric Energy Harvesters Based on Topology Optimization

Vibrational piezoelectric energy harvesters (vPEH) are of great interest in several fields such as autonomous sensors and wireless sensor networks, bird tracking devices, or autonomous miniaturized robotic systems. They capture energy from mechanical vibrations available in the ambient environment and convert it into electrical one to power those systems. Basically, a vPEH is composed of three main parts: the transducer mechanical structure, an electronic interface and the storage unit. In this paper, we focus on the optimization of the mechanical structure of the harvester. To this end, an optimization framework based on topology optimization is proposed. It consists to combine the Solid Isotropic Material with Penalization (SIMP) approach and frequency tuning technique to further increase the efficiency of the harvesters. The fundamental frequency of the design is tuned by considering the mass of the attachment as an optimization variable in addition to the classical density and polarity variables. Two numerical examples, including a new piezoelectric energy harvester configuration, are investigated to demonstrate the effectiveness of the topology optimization framework.