Reduction of Biaxial Bending and Torsion in Ionic Polymer-Metal Actuators through Symmetric Voltage Distribution and Improved Boundary Conditions

Articles in Press

Document Type : Research Article

Authors

1 Department of Mechanical Engineering, SR.C., Islamic Azad University, Tehran, Iran.

2 Modern Automotive Research Center, Department of Mechatronics and Computer Engineering, SR.C., Islamic Azad University, Tehran, Iran

3 Department of Mechanical Engineering, Ab.C., Islamic Azad University, Abhar, Iran,

4 Modern Automotive Research Center, Department of Mechanical Engineering, SR.C., Islamic Azad University, Tehran, Iran

Abstract

In this paper, a combined analytical and numerical framework is presented to reduce or eliminate biaxial bending and torsion in ionic polymer–metal composite (IPMC) actuators. The problem is formulated based on the coupled Nernst–Planck–Poisson model for ion transport and electric field distribution, together with the Euler–Bernoulli beam theory for mechanical response. the main innovation of this study is the integrated design of a two-dimensional symmetric electric field distribution V(x,y) and modified electrochemical–mechanical boundary conditions that simultaneously suppress transverse and torsional gradients. In addition, field- and time-dependent mechanical moduli E and G are introduced to represent viscoelastic effects and electro-mechanical softening more realistically. this comprehensive coupling allows the model to maintain both mathematical and physical symmetry, leading to a uniform ion distribution and balanced bending–torsion response—an advancement beyond previous electro-chemo-mechanical models that considered symmetry only partially or in a single direction. numerical results, using realistic dimensions and a 5 V applied voltage, show that the proposed symmetric field design can reduce transverse bending by up to 87.5% and torsional strain energy by up to 88%. These findings demonstrate that optimized electric field design, appropriate boundary conditions, and field-dependent viscoelastic modeling can substantially enhance IPMC actuator performance and minimize undesired biaxial deformation.

Keywords

Main Subjects

Mechanics of Advanced Composite Structures

Articles in Press, Accepted Manuscript
Available Online from 25 February 2026

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