Piezoelectrically driven morphing structures based on bistable unsymmetric laminates

Due to their anisotropy multilayered fibre-reinforced polymers tend to generate residual stresses, which are primarily influenced by thermal and hygroscopic processes. In the case of an unsymmetric reinforcement architecture, those residual stresses may induce large out-of-plane deformations in thin-walled laminates. Here, specific stacking sequences support the development of so called bistable laminates which are characterised by two distinct deformation states which can be converted by applying forces or bending moments. In combination with appropriate actuator systems, like piezoceramic transducers, such bistable composites can purposefully be used to design compliant mechanisms and novel morphing structures that stand out for a permanent change of shape only by a small energy supply. For the structural analysis and the computation of the necessary actuation voltage to initiate the snap-through of bistable composite structures with piezoceramic actuators, non-linear semi-analytical and numerical simulation methods have been elaborated. First active bistable prototypes have been manufactured and successfully tested.