Design and stiffness analysis of a pitch-varying folded flexure hinge (PFFH)

Based on the theory and characteristics of the coil spring, we proposed a pitch-varying folded flexure hinge (PFFH), which is formed by a series of folded flexure units of variable pitches. With the increase of deformation, different pitch segments are contacted in order to achieve the purpose of variable stiffness. After giving an example design of the hinge structure, a theoretical calculation model of its equivalent spring constant is then derived accordingly. The hinge's stiffness characteristics are discussed and analyzed through both theoretical calculation and finite element analysis (FEA). The results showed that the stiffness of the hinge is varying, and the theoretical calculations results are well-matched with the results of FEA. In addition, the influence of different pitches on the stress and the trend of its stress changes are also analyzed. (C) 2020 Elsevier Ltd. All rights reserved.