Flow-induced buckling of a bistable beam in uniform flow

Recent developments in soft materials enable the design and manufacturing of bistable flexible structures. Their fast snap-through buckling mechanisms have been utilized to introduce fast locomotion. In this paper, we aim to understand the impact of fluid–structure interaction (FSI) on the dynamics of bistable structures. We report the numerical analysis of the snap-through buckling phenomena for several bistable flexible structures fixed at both ends. The motion is driven by the fluid loading of different flow speeds. The large deformation of the bistable structure is coupled with the incoming fluid flow via the Arbitrary Lagrangian–Eulerian (ALE) method. During the snap-through buckling process, the corresponding structural deformation patterns, hydrodynamic force distributions, and fluid patterns are discussed. Larger steady-state deformation is found for the bistable structure, compared to its mono-stable counterpart in the same flow condition. The Cauchy number is found to be the critical parameter affecting the buckling dynamics and dimensionless strain energy stored in the system. A prediction model for the dimensionless strain energy as a function of the Cauchy number is proposed. The hydrodynamic lift force generated by the fluid is found to increase the total strain energy of these bistable structures. The research could provide insight in designing morphable marine energy devices and lightweight bioinspired propulsion systems.