Nonlinear numerical analysis of actuation response of ionic polymer metal composite cantilever considering coupled electrical, chemical, and mechanical fields

Ionic Polymer-Metal composite (IPMC) actuators are very thin sandwich strips with an electroactive polymer in the middle and two metal electrodes on the sides. The coupling of electric, chemical and mechanical fields causes bending deformation, as applying voltage to the electrodes leads to the ions migration through the thickness. In this paper, a nonlinear coupled electrochemical mechanical analysis of the actuation response of an IPMC cantilever is performed. First, the primary electrochemical response is obtained by coupling chemical and electric fields. This equation is solved by the finite difference method using the Newton-Raphson method. This response inserts into the mechanical field. Using the solvent transfer equation, the eigen strain and bending moment rates are obtained. By extracting the water coverage in the boundary layer of cathode and anode, the cantilever end displacement is determined. The results are compared and validated with the finite element simulation done in the current work and previous available studies. The results show reasonably a fit between the response of the actuator and the electrical excitation, and confirm the presented model provides the fast response prediction of the strip. Under 1 Volt excitation, the maximum and residual deflections of the cantilever end were found to be 0.11 and 0.04 of the strip length, respectively, and the cation concentration in the middle of the thickness was calculated to be 1150 mol/m3.