Energy harvesting from bridge vibrations with piezoelectric devices - A feasibility study

We present a feasibility study on the use of piezoelectric devices to harvest the energy connected to the vibrations induced on road bridges by travelling vehicles. We have selected an existing urban bridge as case study and collected the available documentation about its original design. Furthermore, the results of a past experimental campaign on the bridge have provided experimental evidence about the natural frequencies and mode shapes of the structure. Next, we have set up a three-dimensional finite element model of the bridge, which is currently being calibrated to match the results of the experimental dynamic analysis. Besides, we have developed a mechanical model of a laminated cantilever beam with a top piezoelectric layer and a concentrated mass on its free end. Our model applies to laminated beams with general (asymmetric) stacking sequences, thus representing an extension of similar models of the literature. The partial differential equation of motion has been determined and solved in the case of free vibrations under both open- and short-circuit electrical boundary conditions. As a numerical example, a piezoelectric cantilever beam has been designed with the same first natural frequency of the case study bridge.