Synergistic use of piezoelectric and shape memory alloy elements for vibration-based energy harvesting

The efforts for clean and renewable energy have been encouraging a growing interest for vibration-based energy harvesting devices. Piezoelectric materials are remarkable elements to promote electro-mechanical coupling allowing the conversion of the mechanical vibration into electrical power through piezoelectric direct effect. Nevertheless, this promising application is associated with the key challenge to enhance and expand the energy harvesting capacity. In this regard, this work proposes the synergistic use of smart materials, combining piezoelectric and shape memory alloy (SMA) elements. Experimental and numerical analyses are performed showing the enhanced capabilities of the system due to the adaptability provided by shape memory alloys. A piezoelectric beam excited by an electrodynamics shaker is connected with a shape memory alloy element that allows to exploit its remarkable characteristics in order to change system properties with temperature variations through Joule's effect. Thermomechanical tests are performed for SMA characterization. Afterward, nonlinear dynamics of the energy harvesting system is investigated exploiting the SMA adaptive behavior. Results show that the synergistic use of smart materials is able to increase the device bandwidth, improving the system performance for energy harvesting purposes.