The study on the stiffness performance of compliant double parallel four-bar mechanism

The compliant double parallel four-bar mechanism is a classical parallel guiding mechanism. A multiple-step beams model was established to analyze the static stiffness characteristics of the double parallel four-bar mechanism with right angle flexible hinges based on the symmetry of its structure. Formula for calculating the static stiffness was derived by applying singularity function. On the basis of this analysis, the factors influencing the stiffness performance of the double parallel four-bar mechanism were studied from its geometric parameters, and the theoretical model was verified by finite element method. The results show that the stiffness coefficient of the double parallel four-bar mechanism will linearly increase when the width of the flexible hinge increases; When the thickness of the flexible hinge increases, there is an obviously power index increasing on the stiffness; Whereas the coefficient will decrease, when the length of the flexure hinge or the length of the rigid beam increases; and the static stiffness of the mechanism have no relation with the width of the guiding plate. This research is of good significance for analyzing mechanical performance of the double parallel four-bar mechanism, optimizing design of its structure and improving its integrative performance.