Stress Analysis of a Metallic-Reinforced, Small-Length Flexural Pivot Compliant Segment Using the Pseudo-Rigid-Body Model (PRBM)

Abstract

A method based on the pseudo-rigid-body model (PRBM) is presented for the analysis of stress in metallic-reinforced, small-length flexural pivot (SLFP) compliant segments, subjected to end loads or displacement boundary conditions. The analysis method provides the designer with a tool to ensure that stress levels are maintained that are appropriate for the intended application and materials of construction. Simplified equations for stress are presented for both homogeneous polymer and metallic-reinforced composite segments, where the reinforcement shares a neutral axis with a polymer casing. The method is exemplified with two case studies, one, a homogeneous compliant segment, and, two, the segment reinforced with spring steel. The introduction of metallic reinforcement increases the flexural rigidity, but does not reduce the bending stress in the casing of a small-length flexural pivot 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.