A quadristable compliant mechanism with a bistable structure embedded in a surrounding beam structure

A quadristable mechanism with a bistable structure embedded in a surrounding beam structure is developed. Three stable equilibrium positions are within the range of the forward motion of the mechanism, and the fourth stable equilibrium position can only be reached on the backward motion. The quadristability of the mechanism originates from combined compression and bending of the beam structures. Finite element analyses are used to characterize the quadristable behavior of the mechanism under static loading. A design formulation is proposed to find the shape of beams of the mechanism. Prototypes of the mechanism are fabricated and tested. The characteristics of the mechanism predicted by theory are verified by experiments. The design example presented in this investigation demonstrates the effectiveness of the optimization approach for the design of the quadristable compliant mechanism. The proposed mechanism has no movable joints and gains its mobility from the deflection of flexible members. This compliant mechanism can be easily miniaturized, offering a significant advantage for application in micro actuators, micro sensors and microelectromechanical systems.