Horace Walcott

Bio: Horace Walcott is an academic researcher from New York University. The author has contributed to research in topics: Ionic polymer–metal composites & Energy harvesting. The author has an hindex of 2, co-authored 3 publications receiving 125 citations.

Energy harvesting from the tail beating of a carangiform swimmer using ionic polymer-metal composites.

Abstract: In this paper, we study energy harvesting from the beating of a biomimetic fish tail using ionic polymer–metal composites. The design of the biomimetic tail is based on carangiform swimmers and is specifically inspired by the morphology of the heterocercal tail of thresher sharks. The tail is constituted of a soft silicone matrix molded in the form of the heterocercal tail and reinforced by a steel beam of rectangular cross section. We propose a modeling framework for the underwater vibration of the biomimetic tail, wherein the tail is assimilated to a cantilever beam with rectangular cross section and heterogeneous physical properties. We focus on base excitation in the form of a superimposed rotation about a fixed axis and we consider the regime of moderately large-amplitude vibrations. In this context, the effect of the encompassing fluid is described through a hydrodynamic function, which accounts for inertial, viscous and convective phenomena. The model is validated through experiments in which the base excitation is systematically varied and the motion of selected points on the biomimetic tail tracked in time. The feasibility of harvesting energy from an ionic polymer–metal composite attached to the vibrating structure is experimentally and theoretically assessed. The response of the transducer is described using a black-box model, where the voltage output is controlled by the rate of change of the mean curvature. Experiments are performed to elucidate the impact of the shunting resistance, the frequency of the base excitation and the placement of the ionic polymer–metal composite on energy harvesting from the considered biomimetic tail.

Energy Harvesting From Base Excitation of a Biomimetic Fish Tail Hosting Ionic Polymer Metal Composites

Abstract: In this study, we seek to understand the feasibility of energy harvesting from the tail beating motion of a fish through active compliant materials. Specifically, we analyze energy harvesting from the undulations of a biomimetic fish tail hosting ionic polymer metal composites (IPMCs). The design of the biomimetic tail is specifically inspired by the morphology of the heterocercal tail of thresher sharks. We propose a modeling framework for the underwater vibration of the biomimetic tail, wherein the tail is assimilated to a cantilever beam with rectangular cross section. We focus on base excitation in the form of a superimposed rotation about a fixed axis and we consider the regime of moderately large–amplitude vibrations. In this context, the effect of the encompassing fluid is described through a nonlinear hydrodynamic function. The feasibility of harvesting energy from an IPMC attached to the vibrating structure is assessed and modeled via an electromechanical framework. Experiments are performed to validate the theoretical expectations on energy harvesting from the biomimetic tail.© 2013 ASME

Mechanics and electrochemistry of ionic polymer metal composites

Abstract: Ionic polymer metal composites (IPMCs) are electroactive materials composed of a hydrated ionomeric membrane that is sandwiched between noble metal electrodes. Here, we propose a modeling framework to study quasi-static large deformations and electrochemistry of IPMCs. Specifically, IPMC kinematics is described in terms of its mechanical deformation, the concentration of mobile counterions neutralizing the ionomer, and the electric potential. The chemoelectromechanical constitutive behavior is obtained from a Helmholtz free energy density, which accounts for mechanical stretching, ion mixing, and electric polarization. The three-dimensional framework is specialized to plane bending of thin IPMCs. Hence, we propose a structural model, where the moment and the charge stored along the IPMC are computed from the solution of a modified Poisson–Nernst–Planck system, in terms of the through-the-thickness coordinate. For small static deformations, we present a semianalytical solution based on the method of matched asymptotic expansions, which is ultimately used to study IPMC sensing and actuation. We demonstrate that the linearity of IPMC actuation in a broad voltage range could be attributed to the interplay of two competing nonlinear phenomena, associated with Maxwell stress and osmotic pressure. In agreement with experimental observations, our model confirms the possibility of tailoring IPMC actuation by varying the counterion size and the concentration of fixed ions. Finally, the model is successful in predicting the significantly different voltage levels displayed by IPMC sensors and actuators, which are associated with remarkable variations in the ion mixing and polarization energies.