A. Filachek, Burpee Materials Technology, LLC, Eatontown, NJ; J. Burpee, Flexible Stenting Solutions Inc., Eatontown, NJ; B. Beach , Flexible Stenting Solutions Inc. , Eatontown, NJ
All self-expanding stents are required to have a fatigue resistance sufficient for 10 years of equivalent life. The fatigue resistance must be determined in vitro under physiological loading conditions similar to the intended use of the stent. Some stents used in the peripheral vasculature undergo various degrees of bends during limb movement. Typical in vitro test methodology includes a repeated cycle where the stent is initially held straight, then bent to a given radius, then returned to the straight configuration where it is ready for the next cycle. This method can be slow and cumbersome at rates of 1-4 Hz. BMT has developed a calibrated, validated test method which allows for bending fatigue tests to be run at up to 40 Hz. The test results for a given bend radii show an excellent correlation to physiological bending strain locations as determined by ABAQUS finite element analysis. The test provides for severe loading conditions which enable a comparative evaluation in bending fatigue performance from stent to stent during development or when performing competitive analyses.
