Fatigue and Failure Behavior of Homogeneous and Reinforced Compliant Mechanism Segments

Abstract

This paper presents a comprehensive study of the fatigue and failure behavior of both homogeneous and metallic-reinforced compliant segments. Baseline test results are presented for a homogeneous, fixed-free compliant segment constructed of thermoset urethane. The advantages of both polymeric and metallic materials for compliant mechanism construction are leveraged by designing and testing compliant test specimens containing a polymer casing and a metallic reinforcing element. Results obtained from fatigue testing of fixed-free compliant segments in a cyclic loading configuration show that the metallic-reinforced compliant specimens offer superior fatigue performance when compared to the homogeneous baseline specimens. Fractography, both macroscopic and microscopic, is used for a qualitative assessment of the failure behavior. 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.