Numerical studies on the design of self-resetting active bistable cross-shaped structure for morphing applications

Multistable structures are highly attractive for advanced shape-changing (morphing) applications due to their low weights, excellent mechanical properties, and large deformation capabilities. Aim of the paper is to develop a bistable cross-shaped structure, consisting of symmetric and unsymmetric laminates actuated using Macro Fibre Composite (MFC) actuators. The cross-shaped bistable laminates find potential applications in solar tracking models and energy harvesters. The critical snap-through voltages required to change the shapes are investigated using commercially available finite element package. Use of planar MFC actuators to snap the bistable laminate from one equilibrium shape to another, and back again (self-resetting) is demonstrated. For the design of the active bistable cross-shaped structure, the cross-shape is split into four rectangles on the four legs and a square on the middle portion. All the rectangles are made up of unsymmetric laminates, and the central portion is designed with a symmetric laminate. MFC actuators are bonded on both sides of the four legs to trigger snap-through and snap-back actions. An attempt is made to address the possible design difficulties arising from the additional stiffness contribution by MFC layers on the naturally cured equilibrium shapes of cross-shaped bistable laminates. Suitable potential applications using the designed self-resetting active bistable cross-shaped laminate are proposed.