A Prestrained Bistable Composite Gridded Structure

Bistable composite structures have attracted growing interest in morphing applications to aerospace industry. Here, we device a novel prestrained bistable composite gridded structure, consisting pairs of prestrained composite strips on both sides and oriented in 90°. This is achieved by employing the elastic fibre prestressing (EFP) technique, where a plain-weave carbon prepreg was stretched in two directions at a constant strain level, and the tensile strain was maintained throughout the curing process to produce a prestrained composite trip. Upon load removal, recovery from the prestrained carbon fibres generates compressive stresses and interacts with thermal residual stresses, which in turn changing the in-plane stress level within a composite structure and induce out-of-plane deflections. Therefore, the bistability is generated from the pairs of the oriented prestrained composite strips, their deflections give opposite cylindrical configurations to the mid-plane. Here, we presented further details on the biaxial fibre straining rig; samples were produced with different prestrain levels, in order to reveal the underlying mechanisms from the fibre prestraining. These results provide valuable insights for the design of aerospace deployable structures.