A nonlinear model of an actuator

We present two models based on the theory of nonlinear elasticity of a photo–actuator consisting of a mixture of a polymer matrix with carbon nanotubes. Both models are generalizations of the one proposed by Ahir and Terentjev 1 in which the actuation mechanism is modelled as a contraction of a given carbon nanotube in response to an external stimuli. In the first model, a slight variation is introduced in the projection onto the axis of the pre–strain. This new computation improves the result reported in 1 for carbon nanotube photo–contraction when a 10% pre-strain is applied. In our second model we use a nonlinear constitutive equation to describe the mechanical response of the composite. We show that by a suitable selection of the parameters in the model, consistent with the average constitutive parameters (Young modulus) reported in the literature, we can further improve on the average carbon nanotube contraction for a 10% pre–strain threshold.