Modeling the nonlinear deflection of elliptical-arc-fillet leaf springs

Abstract

Leaf spring is widely used in many large-stroke compliant mechanisms, such as positioning stage and flexural pivot, for its distributed compliance. However, the uniform cross-section rejects the possibility of improving the stress concentration and center shift of leaf springs. To this end, a generalized model is proposed to contain multiple types of leaf springs with variable cross-sections for large deflection applications. An element integral method based on the beam constraint model (EIMBCM) is provided to model the nonlinear properties of elliptical-arc-fillet leaf springs (EAFLS), such as nonlinear deflection and center shift. Properties comparison of EAFLSs with specific parameters indicates that the generalized model can provide a comprehensive parametric method for mechanism design and avoid the empirical choice. The accuracy of the proposed nonlinear model is verified by nonlinear finite element results. The efficiency of the proposed model is illustrated by the design of a guiding mechanism.