Dynamic responses of SMA-epoxy composites and application for piezoelectric energy harvesting

Piezoelectric energy harvesting technologies provide effective measures for energy supply of wireless sensor network. In this work, shape memory alloy (SMA) reinforced epoxy composites was designed as the substructure of vibration energy harvester. Based on Hamilton's variational principle, the theoretical model of vibration piezoelectric energy harvester was developed, and the voltage output of the energy harvester at different temperatures was simulated. The varying stiffness characteristics of the SMA-epoxy composites were theoretically investigated and experimentally proved to be effective. By measuring the vibration mode of the energy harvester, we discussed the influence of SMA-epoxy and temperature on dynamic response. Through the thermal-vibration experiments, the energy harvesting behavior was analyzed. The simulation and experimental results show that the natural frequencies can be shifted to not only to the smaller direction but also to the higher frequency direction, which could be altered from 39 Hz to 41.8 Hz. And the theoretical prediction on energy harvesting performance considering the temperature influences of SMA-epoxy composites is proposed and the results is consistent with experimental ones.