Analytical Modeling and Analysis of an Annulus-Shaped Flexural Pivot

Annulus-shaped flexural pivots (ASFP), composed of three or more identical leaves that are symmetrically arrayed in an annulus, can be used widely in compliant mechanisms for their excellent performances. This paper proposes the accurate load-rotation models of ASFP with three straight leaves, which include the load cases of bending moment combined with horizontal force and vertical force. Firstly, the load-rotation models of ASFP are derived based on the Beam Constraint Model (BCM). Then, the rotational stiffness and buckling characteristics are analyzed based on the derived models. Finally, the accuracy of the models is validated by the finite element analysis (FEA). The relative error of the load-rotation models is within 7% for various load cases even if the rotational angle reaches 0.07 (4°). The results show that the models are accurate enough to be used for initial parametric designing of ASFP.