Symmetry Optimization of a Three-Segment Fully Compliant Bistable Mechanism for Switching Forces in Forward and Backward Directions

The symmetry of the switching forces of the fully compliant bistable mechanism is an important factor affecting its keeping stability in the equilibrium state. However, existing research on the three-segment fully compliant bistable mechanism (TSFCBM) does not reveal the influence law of its structural geometric parameters on the symmetry of the switching forces. Hence, this paper introduces the bistable characteristic parameter, establishes the optimization design model of the switching forces symmetry of the TSFCBM, and investigates the influence mechanism of the structural geometric parameters on the switching forces symmetry. In addition, this study obtains the relationships between the structural geometric parameters of the TSFCBM with optimal switching forces symmetry and verifies the optimization result by simulation. Through extensive experiments on the switching forces symmetry of the TSFCBM, the relative error of the bistable characteristic parameter obtained by theoretical calculations, finite element simulations, and experimental measurements is less than 15.5%, verifying the correctness and effectiveness of the optimization model and the influence law. The established optimization model and the revealed influence law provide the theoretical basis and practical method for designing a TSFCBM with switching forces symmetry that achieves the parametric design of a TSFCBM.