Dynamic control for morphing of bi-stable composites

Adaptive structures have been the focus of much research due to performance gains not possible to achieve using conventional designs. Within this context, the idea of morphing promises augmented capabilities in terms of manoeuvrability, fuel efficiency and the ability to perform dissimilar tasks in an optimal manner. To achieve morphing, materials capable of changing shape requiring minimum actuation are necessary. Bi-stable composites are a type of composite structures which have two statically stable configurations. This bi-stability property, resulting from locked in-plane residual stresses, has attracted considerable attention from the adaptive structure community for morphing structures as actuation is no required to hold each stable configuration. The change between stable states is physically realised as a jump phenomenon or snap-through, which is strongly non-linear in nature. Morphing strategies exploiting snap-through have been studied showing encouraging preliminary results. This article exploits the dynamic response of bi-stable composites as a means of augmenting the actuation for morphing control. A morphing strategy targeting modal frequencies leading to snap-through of the structure is successfully developed. This results in a full-state configuration control by inducing and reversing snap-through as desired. The strategy is tested on a specimen using Macro Fiber Composites as smart actuators validating the proposed concept.