Analysis for Stiffness of Large-Deformation Flexure Hinge and Its Application

The paper discusses the stiffness of flexure hinge made by rubber material. A revolute compliant joint made by rubber is proposed which offer improvements over existing flexures made by metal in the qualities of large range of motion, long lift, and reduced weight. Based on the theory of nonlinear deformation and the characters of strain-energy functions of Mooney-Rivlin model, the stiffness of rubber flexure hinge is obtained by piece-wise linearization of the stress-strain curve. Some geometric parameters such as t/R ratios affecting the stiffness of rubber hinge are calculated. Thereby, the problem of the relationship between moment and large angle deformation is resolved. The result from the FEA performed on the various flexures to find the angle displacement shows ideal consistency. Finally, the application of rubber flexure hinge using in the compliant thorax of micro air vehicle with flapping wings is given.