Predictive Electromechanical Model for Energy Scavengers Using Patterned Piezoelectric Layers

The piezoelectric transduction mechanism is widely used in passive sensing, health monitoring, and energy harvesting. Plate-type energy harvesters are usually discouraged; however, piezoelectric layers on a substrate in a certain pattern were found to be suitable for harvesting energy from a wider band of frequencies. However, to understand the theoretical behavior of the harvesters with any arbitrarily shaped piezo patch, a detailed mathematical model is lacking. This paper proposes a comprehensive analytical model to calculate the frequency response function (FRF) from simply patterned piezoelectric layers. A generalized mathematical form is presented for an arbitrary rectangular piezoelectric patch placed on a host plate. The strain-rate damping mechanism is incorporated for better and more accurate results. First, a comparative study on the strain-rate damping effect is presented by placing the piezoelectric layer on the entire plate. Without strain-rate damping, the model incorrectly estimates voltage output. Further, a methodology through a genetic algorithm optimization process is proposed to generate the required pattern of piezoelectric layers tailored to a desired requirement. With the proposed generalized mathematical model, the voltage output from the harvester with any particular shape and size of piezoelectric layers can be calculated predictively. (C) 2014 American Society of Civil Engineers.