  IPMCs consist of a Nafion(R) ionic polymer film coated on both sides with a
thin layer of metallic electrodes. The polymer completely dissociates when it
is saturated with water, releasing small cations while anions remain bound to
the polymer chains. When this strip is subject to an orthogonal electric field,
the cations migrate towards the negative electrode, carrying water away by
osmosis. This leads to the bending of the strip. We have previously published a
modelling of this system based on the thermodynamics of irreversible processes.
In this paper, we use this model to simulate numerically the bending of a
strip. Since the amplitude of the deflection is large, we use a beam model in
large displacements. In addition, the material permittivity may increase with
ion concentration. We therefore test three permittivity models. We plot the
profiles of the cations concentration, pressure, electric potential and
induction, and we study the influence of the strip geometry on the tip
displacement and on the blocking force. The results we obtain are in good
agreement with the experimental data published in the literature. The variation
of these quantities with the imposed electric potential allow us to
discriminate between the three models.
