Finite element analysis and testing of flexure bearing elements

Interest in flexure bearings has been kindled by the need to develop reliable and long-life cryocoolers for space applications. The complexity of the geometrical profile and the kinematics involved in the operation of the flexure bearing disc under stringent requirements of high fatigue life and radial stiffness, precludes the use of exact analytical techniques in its design. Hence, use of Finite Element Method (FEM) is indispensable in this context, as has been seen in a series of recently published papers. However, no accurate validation of the maximum stresses predicted by the FE analysis has yet been reported. This paper presents non-dimensional design curves for a flexure disc with a spiral arm configuration for a range of sizes and strokes. These curves are the results of analysis using FEM. It further reports an optical method for accurate measurement of the associated strains on the flexure disc so as to validate the analytical results.