Investigation of the Effect of a Nonlinear Ion Concentration Function on the Electromechanical Behavior of Ionic Polymer–Metal Composites

Subject Areas :

Reza Poureini ¹ , Hamid Soleimanimehr ^{2 *} , Navid Seyedkazem Viliani ³ , Ali Abdollahi ⁴

1 - Ph.D. Student, Department of Mechanical and Aerospace Engineering, SR.C., Islamic Azad University, Tehran, Iran
2 - Associate Professor, Modern Automotive Research Center, Department of Mechanical and Aerospace Engineering, SR.C., Islamic Azad University, Tehran, Iran
3 - Assistant Professor, Department of Mechanical Engineering, Ab.C., Islamic Azad University, Abhar, Iran
4 - Associate Professor, Modern Automotive Research Center, Department of Mechanical and Aerospace Engineering, SR.C., Islamic Azad University, Tehran, Iran

Received: 2025-07-11 Accepted : 2025-08-30 Published : 2025-07-26

Keywords: IPMC, Nonlinear Ion Concentration, Euler-Bernoulli Beam, Energy Method, Nernst-Planck, Poisson Equation, Biaxial Bending,

Abstract :

The effect of nonlinear ion concentration distribution and electric potential gradient on the induced biaxial moments in ionic polymer–metal composite (IPMC) actuators is investigated. To accurately model the bending behavior, a combined approach is employed, integrating the Euler–Bernoulli beam theory, the principle of minimum potential energy, and a nonlinear field- and time-dependent mechanical property model. In this framework, the ion concentration distribution is assumed to be nonlinear along both longitudinal and transverse directions. The coupled electro-ionic interactions are analyzed using the Nernst–Planck and Poisson equations. Numerical results demonstrate that adopting a nonlinear ion distribution leads to nearly equal induced electrical moments in both directions at the mid-plane, significantly reducing biaxial bending and yielding a more balanced deformation profile. This approach yields a 95% reduction in transverse moment compared to the linear model, underscoring the superior effectiveness of the proposed nonlinear method in mitigating undesirable biaxial bending in IPMC actuators.

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