Optimum Study of Power Efficiency of a THUNDER Harvester

A piezoelectric-coupled finite element model for a THUNDER harvester (THin layer UNimorph DrivER) is developed and studied in this work. THUNDER is a curved piezoelectric energy generator developed by NASA Langley Research Center, which has better vibration absorption and higher energy recovery efficiency at low-frequency vibration compared to a flat PZT harvester. To apprehend the piezoelectric effect of the THUNDER harvester, finite element method was used to perform the piezoelectric coupled field analysis. Piezoelectric THUNDER harvester was studied under cantilever boundary condition. In the model, the excitation forces are distribution force allied on the top of the dome line. An electric circuit element was used to create load resistance across the electrodes to obtain the generated voltage and power. The effect of the geometric parameter was investigated via the varying radius of curvature, which affects the resonance frequency, voltage, and power output of the THUNDER. Good agreement between finite element analysis and experimental results were also observed. In finite element analysis: Modal analysis was carried out to find the resonance frequency at which maximum performance characteristics of the THUNDER can be achieved. Then, the harmonic analysis was performed to distinguish the voltage and power output variation as the load resistance changes. The effects of the varying radius of curvature on the power efficiency of the THUNDER were summarized.