Effect of supporting layer materials on performances of piezoelectric cantilevers

In this paper, a performance comparison between several piezoelectric cantilevers sharing similar piezoelectric patches but having different supporting structures is carried out. It is indeed known that supporting structure material affects the power output of the device through structural damping and position of the elastic axis, whereas stiffness and mass per unit length have an influence on the modal frequencies. For this reason, three different metallic materials (brass, aluminum and steel) and a bioplastic (PLA) are chosen, the latter being 3D printed. 3D printing guarantees an easy prototyping of the cantilever plate and its clamping block, allowing for innovative shapes and a completely sustainable production of piezoelectrics once lead-free solutions for the piezoelectric will be economically affordable. The comparison primary concerns the voltage-to-acceleration frequency response function, focusing on the first bending mode response, and then takes into account electric power output per volume of the ceramic layer of the different devices. A comparison between the most performing of the considered harvesters and a commercial on-the-shelf device is finally carried out, demonstrating how the support layer choice can significantly influence the energy harvester performance.