Twisted shape bi-stable structure of asymmetrically laminated CFRP composites

Carbon fiber reinforced plastic (CFRP) laminated composites, called bi-stable composites, are applied as soft morphing host structural component. These bi-stable composites have two cylindrical stable states which have parallel direction between fiber direction of composites and principle curvature of bi-stable shape. Their final curvature can be tailored by the initial curvature. However, the cross-ply composites have twisted shape in a certain negative initial curvature. These twisted shapes also have bi-stability. Herein, the reasons for the twisted shapes are discussed from a mechanical perspective. In addition, the twisted shape was simulated by a developed analytical model considering the discussed mechanical mechanism. The simulation results show that the CFRP laminated composites have two kinds of bi-stable states (conventional shape or twisted shape) and a mono-stable state with respect to the negative initial curvature. These analytical results were verified by comparing them with those obtained by finite element analysis (FEA).