Finite element model for extensional actuation in ionomeric polymer transducers

Ionomeric polymer transducers (sometimes called ionic polymer-metal composites or IPMCs) have received considerable attention in the past ten years due to their ability to operate as distributed electromechanical actuators and sensors. An ionic polymer transducer is made of an ionomeric membrane sandwiched between two conductive electrodes. The potential of a new actuation mechanism actuated through the thickness of the membrane is presented in this paper. Compared to traditional bending experiments, bending is constrained by sandwiching the membrane between two solid metal plates and force is measured across the thickness of the actuator in the state of extension. Although a complete understanding of fundamental actuation mechanisms in extensional ionic polymer transducers is still under debate, in order to make use of their potential, it is needed to establish a valid mathematical model to provide enhanced degrees of understanding, predictability, and control etc. The principle of thermal expansion of a bimetallic strip based on finite element method (FEM) is used to simulate the extensional actuation. An electromechanical coupling model that relates strain and voltage is assumed, and the model successfully predicts the extensional response. Theoretical and experimental results demonstrate that the model is practical and effective.