Optimization of retractable structures utilizing bistable compliant mechanism

An optimization approach is presented for a retractable structure consisting of bistable compliant mechanism. The structure is modeled using truss and beam elements, and snapthrough behavior is utilized to generate large deformation under small input displacement and recover the initial shape by application of a small reversal force. The parameters such as nodal locations and cross-sectional areas of members are optimized to minimize the error of nodal displacements from the specified target values. It is shown that the deformed shape, required input force, and stiffness against lateral loads can be controlled independently by modifying nodal locations and stiffnesses of different sets of members. It is also shown through an example of roof model that the maximum load required for shape transformation can be effectively reduced by utilizing the flexibility and self-weight of structure.