Electroactive polymer actuators: theory and computations

Abstract

Electroactive polymer actuators are devices composed of polymeric materials which display mechanical actuation under an applied electric field. This mechanical actuation coupled with the relative compliance of polymeric materials renders electroactive polymer actuators an attractive choice for soft robotics applications, where they are sometimes referred to as “artificial muscles”. We present continuum-mechanical theories and finite element computations for three common types of electroactive polymer actuators: (1) ionic polymer-metal composites (IPMCs), (2) piezoelectric polymers, and (3) dielectric elastomers.

Highly-coupled physical phenomena drive the actuation mechanism for each of these electroactive polymers. We present theory which accounts for electro-chemo-mechanical coupling in the case of ionic polymer-metal composites and electro-mechanical coupling in the case of piezoelectric polymers and dielectric elastomers, all within a thermodynamically consistent, finite deformation framework. We report demonstration computations of electroactive polymer devices using our own finite element implementations of the IPMC theory and piezoelectric polymer theory and an existing implementation of the dielectric elastomer theory. The demonstration computations reported include bending actuators, a biomimetic fin, a soft robotic gripper, and a piezoelectric serpentine ribbon. The theory and simulation capabilities presented in this work lay a foundation of modeling tools which hold great practical utility for the fast-growing field of soft robotics.