Bistable variable stiffness laminates - novel manufacturing and modeling strategies

Bistable laminates offer a path to energy-efficient and multi-functional structures, with potential applications in various engineering domains. Recent advancements in composites research indicate that replacing conventional straight fiber composites with variable stiffness (VS) composites opens up new avenues for enhancing the design space of shape-morphing structures. The production of VS laminates requires the use of advanced manufacturing techniques that enable the precise placement of composite tape modules in the specified orientations. This paper proposes an innovative approach to manufacturing bistable VS laminates, in which a detailed experimental campaign to manufacture and test bistable VS laminates is presented. Two specific sets of VS families have been selected, and their bistable shapes and snap-through requirements are systematically evaluated. The paper further seeks to provide validation for an efficient semi-analytical and numerical model proposed by the authors in their previous work by experimentally observing bistable characteristics. The theoretical and numerical predictions on generating a plethora of bistable configurations and tailoring the snap-through requirements using VS laminates are found to be in good agreement with experiments. The studies strengthen the conclusion that replacing conventional fibers with curvilinear fibers can substantially expand the design space, providing a diverse range of bistable shapes for morphing applications.