A Hyperelastic Porous Media Framework for Ionic Polymer-Metal Composite Actuators and Sensors: Thermodynamically Consistent Formulation and Nondimensionalization of the Field Equations

Document Type

Article

Publication Date

8-18-2021

Publication Title

Smart Materials and Structures

Volume

30

Issue

9

First page number:

1

Last page number:

27

Abstract

Ionic polymer-metal composites (IPMCs) are smart materials that exhibit large deformation in response to small applied voltages, and conversely generate detectable electrical signals in response to mechanical deformations. The study of IPMC materials is a rich field of research, and an interesting intersection of material science, electrochemistry, continuum mechanics, and thermodynamics. Due to their electromechanical and mechanoelectrical transduction capabilities, IPMCs find many applications in robotics, soft robotics, artificial muscles, and biomimetics. The current literature is sparce in multiphysics models that account for large deformations, coupled ion-solvent transport, the porous structure of the membrane, and lossy electrodes under finite-strains. This study addresses this by developing a new, hyperelastic porous media modeling framework for IPMCs using the principles of continuum thermodynamics and multiphasic materials. This framework compactly captures the broadest strokes of IPMC modeling methodologies, summarizing them in the form of general constitutive requirements placed on thermodynamic potential describing the polymer skeleton. A simple IPMC model is derived under this framework which captures the finite-strain deformation of a hyperelastic material, accounting for the coupled ion-solvent transport through the porous polymer, and resistive electrodes deforming with the skeleton. The resulting governing equations are further cast into a generalized nondimensional formulation, and an expansive set of unique dimensionless ${{\Pi }}$-groups are derived for IPMC actuator and sensor devices. This new framework and the nondimensional formulation lay the groundwork for future research and an expansive characterization of IPMC transduction phenomena via dimensional analysis.

Disciplines

Materials Science and Engineering | Mechanical Engineering

Language

English

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