Fiber-Directed Conjugated-Polymer Torsional Actuator: Nonlinear Elasticity Modeling and Experimental Validation

Existing conjugated-polymer actuators typically take the form of benders or linear extenders. In this paper, a conjugated-polymer-based torsional actuator is proposed by embedding helically wound fibers into a conjugated polymer tube during the polymer-deposition process. Upon actuation, the electrolyte-soaked tube swells, and consequently, produces torsion and other associated deformations because of fiber-induced mechanical anisotropy of the composite material. A nonlinear elasticity-based model is presented to capture the torsion, elongation, and dilation of the tube. Experiments on tubular actuators with different thicknesses, fiber-winding angles, and diameters confirm the aforementioned deformation modes and validate the effectiveness of the proposed model.