Abstract
Fixed-clamped flexures are one common component of compliant mechanisms which remain difficult to design due to their unique force- and stress-deflection response profiles. In this work, a stress-deflection model for fixed-clamped flexures is proposed that utilizes a modified pseudo rigid body model. Special analysis is carried out on the characteristic radius factor, a parameter to which model accuracy is particularly sensitive. Effects of both deflection magnitude and flexure geometry on this parameter are explored and considerations for optimal parameter selection are included. Finite element analysis demonstrates that the model is able to predict the vertical applied force, horizontal reaction force, and maximum von Mises stress with a maximum percent error less than 3.5% at yield for a range of steel flexure topologies. Using the model to predict behavior of flexible polypropylene flexures undergoing larger deflections, the model has a maximum error between 4–14% using static model parameters, compared to 74–96% using the small deflection equations. The distinct combination of axial and bending stresses experienced in fixed-clamped flexures has made mechanisms which use these members challenging to design. This work provides a model that designers, engineers, and researchers can draw from to understand stress profiles present in these flexible members.
