Design optimization of stiffness characteristics for bistable composite laminates

Asymmetric composite laminates can have a bistable response to loading. The potentially large deflections which can be achieved during snap-through from one stable state to another with small and removable energy input make them of interest for a wide range of engineering applications. After 30 years of research effort the shapes and response to applied strains of laminates of general layup can be quantitatively predicted. With attention switching to the incorporation of bistable laminates for real world applications this paper presents optimization of bistable composites enabled by an analytical solution for a simplified orthogonal laminate design. The optimization formulation maximizes the bending stiffness in the direction of known loading condition whilst the bending stiffness in the direction of snap-through is minimized. The deflection requirement is applied as a constraint. We find the design problem to have multiple local optima, with the global optimum differing from the traditional high deflection cross-ply solution.