SUMMARY

Macro-fiber composite (MFC) piezoelectric materials with interdigitated electrodes employ the 33-mode of piezoelectricity and strike a balance between deformation and force capabilities. MFCs are used in a variety of applications employing the direct and converse effects, spanning from sensing and energy harvesting to morphing and bio-inspired locomotion. Most existing literature considers linear material behavior for geometrically linear oscillations, but in many applications, material and geometric nonlinearities are easily pronounced and linear models often fail to represent and predict the governing dynamics. The theoretical and experimental research presented in this work explores nonlinear nonconservative elastodynamics of bimorph MFC cantilevers for the specific problems of resonant energy harvesting and actuation. In the energy harvesting component of this work, a wide range of mechanical base excitation levels are employed to study material nonlinearities and their interaction with geometric, inertial, and dissipative nonlinearities for a range of electrical load resistances. In the resonant actuation component, bimorph MFC cantilevers are tested under voltage actuation for a broad range of electric field levels below the coercive field. In vacuo resonant actuation experiments are also performed to mitigate nonlinear fluid damping, and thereby pronounce the nonlinear effects of interest more clearly. The mathematical framework presented here, which is validated through rigorous experiments, as well as the identified nonlinear parameters, can be used for a number of applications employing MFC piezoelectric structures.