Nonlinear dynamics of curved IPMC actuators undergoing electrically driven large deformations

The nonlinear dynamics of curved ionic polymer–metal composite (IPMC) actuators having large tip displacement and periodical jumping locomotion was investigated experimentally. Through snap-through phenomena, the actuator generates much larger tip displacement and shows abrupt jumps in the transitions of upswings and downswings with low input energy. Two curved IPMC cantilever actuators having two different constant curvatures of 0.01 mm−1 and 0.02 mm−1 were fabricated through thermal treatment from flat IPMCs, simultaneously with no residual stress. As-fabricated IPMC actuators were tested to evaluate the effect of initial curvature under static and dynamic electrical excitations. Unlike the case of the flat IPMC actuator, asymmetric characteristics in step and harmonic responses were investigated in the curved IPMC actuators. Also, at relatively higher input voltage, snap-through phenomena were observed with much larger transverse displacements and periodical abrupt jumps of the instant speed. This revealed jumping movements between the multiple equilibrium points. The results show that optimum curvatures for better bending performance of curved cantilever IPMCs exist and that this snap-through mechanism could be applied to IPMC actuators by considering their soft and flexible properties and the geometric structures.