Hydroelastic impact of piezoelectric structures

In this paper, we experimentally study the hydroelastic impact of an active flexible wedge on an otherwise quiescent fluid. A piezoelectric transducer is incorporated in the wedge with the twofold intent of measuring structural deformations during the impact and assess the feasibility of piezoelectric energy harvesting in fluid entry problems. Experiments are conducted in a drop-tower, in which the drop height of the wedge from the water surface is parametrically varied to investigate the effect of the impact velocity on the piezohydroelastic response of the active structure. In these tests, the electrodes of the transducer are either open-circuited, to demonstrate piezoelectric sensing, or shunted with a resistor, to characterize piezoelectric energy harvesting. Our results demonstrate that the piezohydroelastic response of the structure is controlled by the impact velocity, which differentially regulates both the amplitude and frequency content of the electrical signals. Experimental results are interpreted through a distributed model based on linear plate theory and Wagner's approximate solution for the hydrodynamic load. Findings from this work are expected to find application in marine structures, where piezoelectrics can be used as sensors, to monitor the state of health of the structure, or as energy harvesters, to recover part of the energy that is otherwise lost in undesired vibrations.