Experimentally Validated Nonlinear Electrohydroelastic Euler-Bernoulli-Morison Model for Macro-Fiber Composites With Different Aspect Ratios

Abstract

Macro-fiber composite (MFC) piezoelectric structures with interdigitated electrodes can be used for effective hydrodynamic thrust generation by underwater actuation as well as low-power electricity production from underwater vibrations for powering wireless electronic components. In order to develop high-fidelity models to predict the electrohydroelastic dynamics of MFC structures, mixing rules based electroelastic mechanics modeling is coupled with the global electroelastic dynamics based on the Euler-Bernoulli kinematics and the nonlinear fluid loading based on Morison’s semi-empirical model. The focus is placed on the dynamic actuation problem for the first two bending vibration modes under geometrically, materially, and piezoelectrically linear, hydrodynamically nonlinear behavior. The electroelastic and dielectric properties of a representative volume element (piezoelectric fiber and epoxy matrix) between two subsequent interdigitated electrodes are correlated to physical parameters of MFC bimorphs and validated for different MFC types that have the same overhang length but different widths. Following the process of in-air electroelastic model development and validation, underwater experiments are conducted for different length-to-width aspect ratios (L/b), and empirical drag and inertia coefficients are extracted for Morison’s equation. The repeatability of these empirical coefficients is demonstrated for experiments conducted using aluminum cantilevers of different aspect ratios. Convergence of the nonlinear electrohydroelastic Euler-Bernoulli-Morison model to its hydrodynamically linear counterpart with increased L/b values is also reported. The proposed model, its harmonic balance analysis, and experimental results can be used for parameter identification as well as aspect ratio optimization for underwater piezoelectric actuation, sensing, and energy harvesting problems.