A novel approach to determining piezoelectric properties of nanogenerators based on PVDF nanofibers using iterative finite element simulation for walking energy harvesting

This study presents the experimental characterization and finite element investigation of a piezoelectric nanogenerator based on electrospun poly(vinylidene difluoride) (PVDF) nanofibers walking energy harvesting applications. The piezoelectric response of nanogenerator device was experimentally evaluated under low frequency cyclic impacts using PiezoTester. The impact test was then simulated and the obtained experimental applied force-time curve is implemented into the finite element model as the impactor external force. Based on mentioned procedure, a novel iterative finite element simulation was then introduced to determine the piezoelectric properties of PVDF nanofibers to avoid any redundant experiments. The experimental voltage-time was compared with voltage time obtained from optimized finite element model and a reasonable agreement was achieved between the numerical and experimental curves. Thereinafter, as a case study, a PVDF nanofibers nanogenerator integrated foam (PNIF) was simulated to use as an energy harvester in the shoe insole. The validated finite element model was then constructed to optimize the PNIF elasticity modulus to reach the maximum efficiency of energy harvester during human walking. The results showed that the best efficiency of the energy harvesting is achieved for 211.27kPa PNIF modulus, which can generate 15.1V. These results lead to the establishment of engineering design rules in the industrial scale for wearable power harvesting devices in the footwear industry.