Design and Optimization for Casing of Thickness Mode Piezoelectric Roadway Energy Harvester
The impact of several casing design variables for thickness-mode piezoelectric roadway energy harvesters using soft lead zirconate titanate (PZT) were evaluated. The influence of mechanical fastener induced pre-stress on PZT examined analytically and experimentally. It was determined from an analytical relationship that fastener induced pre-stress had an inverse relationship with the number of mechanical fasteners used and their stiffness with the change in force a PZT element incurs. The experiments performed to determine the effect of the mechanical fasteners on power generation was inconclusive. The casing's top lid mass, and top lid thickness influence on power generation was experimentally tested. Experiments showed that both the top lid weight and thickness influenced the power generation. The thickness relation was also verified using a COMSOL finite element analysis (FEA) simulation. All experiments were performed using an MTS Acumen material testing machine. Several top lid designs which increased the stiffness of the lid were evaluated using Abaqus FEA. It was determined that increasing the stiffness of the lid improved the stress distribution pattern on the PZT element beneath the lid. A novel two-piece lid design for a thickness mode roadway piezoelectric energy harvesting casing was designed and evaluated in Abaqus finite element analysis. The design was shown to improve the stress distribution pattern in the piezoelectric element beneath it.