Stress Analysis of a Fixed-Free Compliant Segment using the Pseudo-Rigid-Body Model (PRBM) Concept

A method is presented to analyze stress in ambient-temperature, fixed-free compliant segments subjected to end load or displacement boundary conditions. The analysis method outlined herein relies on key outputs from the pseudo-rigid-body models (PRBMs). Simplified equations for stress are presented for both homogeneous and metallic-reinforced segments. Stresses in both the polymer compliant segment and the metallic reinforcing element are addressed to enable a comprehensive stress analysis method. The stress analysis method is exemplified by using two design cases: one, a homogeneous compliant segment, and two, a compliant segment reinforced with a spring steel element. The results showed that introducing a metallic reinforcement increases the flexural rigidity, but does not reduce the bending stress in the casing unless the cross-sectional thickness is reduced. This vein of research is undertaken using metallic reinforcement (inserts) toward the development of a new class of compliant mechanisms with significantly greater performance, particularly insofar as the problems of fatigue and creep are concerned.