Modeling, validation and design analyses of a piezoelectric cymbal transducer for non-resonant energy harvesting

It is difficult to characterize the Piezoelectric Cymbal Transducer (PCT) using the equivalent circuit method and/or dynamic modeling alone. This paper uses a validated Finite Element Model (FEM) that encompasses both mechanical and electrical aspects of the PCT design for energy harvesting applications. The PCT consists of a piezoelectric disk sandwiched between two metal end caps with shallow cavities that act as mechanical force amplifiers to increase the force on the piezoelectric disk. A special focus has been given to the calculation of the power harvested by the PCT when this is connected to a load resistor and excited by a force of frequencies similar to human gait (2 Hz). It was found that the electrical resistive load, the dimensions of the piezoelectric disk and of the end caps had significant effects on the power output from the PCT. A PCT of dimensions Ø30x4.6 mm with an end cap thickness of 0.33 mm was able to harvest 0.07 mW of power under a 50 N force at 2 Hz (with 3 MO resistive load).