S. Kari, FEA Solutions, Windsor, CA; P. Adler, Medtronic Cardiovascular, Santa Rosa, CA; J. Allen, Medtronic Vascular, Santa Rosa, CA
Endurance limit analysis and testing requires an accurate determination of the strain environment a device experiences in its life cycle (crimp strains, mean strain and strain amplitudes) as well as the strain capability of the processed device. Surrogate fatigue specimens that represent a critical portion of a device can be designed through finite element analysis to experience the requisite strain life cycle, and in addition, can be efficiently tested to failure in a controlled strain environment. The surrogate should be processed in a similar manner as the parent device to ensure accurate material microstructural properties as well as surface finish characteristics. In this paper, we present the design, analysis and testing of a fatigue test specimen to determine a fatigue endurance limit to be used in the design assessment of a medical device. Finite element analysis was used to predict the strain-displacement response of the specimen in order to parametrically determine the fatigue endurance limit through high cycle testing. High cycle testing was conducted to produce an endurance limit design envelope to ensure safe device performance.
Summary: In this paper, we present the design, analysis and testing of a fatigue test specimen to determine a fatigue endurance limit to be used in the design assessment of a medical device. Finite element analysis was used to predict the strain-displacement response of the specimen in order to parametrically determine the fatigue endurance limit through high cycle testing. High cycle testing was conducted to produce an endurance limit design envelope to ensure safe device performance.
