Optimization of Stiffness Characteristics for the Design of Bistable Composite Laminates

Asymmetric composite laminates can have a bistable response to mechanical loading. The large deflections that can be achieved by snap-through from one stable state to another, along with a need for small and removable energy input, make them of interest for a wide range of engineering applications. After 30 years of research efforts the shapes and response to applied strains of laminates of general layup have been well characterized. More recently, with the development of smart actuators, the design and application of bistable laminates has been considered. This paper presents an optimization technique for the design of bistable laminates enabled by an analytical solution for an asymmetric laminate design. The optimization formulation maximizes the bending stiffness in the direction of known loading condition while the bending stiffness in the direction of snap-through is minimized. A minimum deflection requirement is applied as a constraint. The design problem has multiple local optima, with the global optimum not intuitively obvious from the problem definition, differing from the typical high-deflection cross-ply solution.