February 1, 2010
Dr. Brad James, Principal Engineer and Director of the Center for Materials Science and Corrosion Engineering, and Dr. Robert Sire, Senior Managing Engineer in the Center for Mechanical Engineering, recently published an article in January 2010 edition of Biomaterials on fatigue life assessment and validation techniques for metallic implants.
Vascular implants, such as cardiac valve prostheses, stents, and other devices are often subjected to complex loading conditions in vivo, which can include pulsatile pressure cycling, bending, torsion, tension, and compression, among others. At an average of 72 heartbeats per minute, pulsatile loading alone produces approximately 40-million cycles per year. With design lives of 10 to 15 years, fatigue performance assessment and validation of these devices are critical for the designer, as mechanical failure can have serious consequences. Historically, various fatigue-life assessment approaches have been used to validate endovascular device fatigue performance, including durability testing, stress/strain-life analysis, and damage tolerance-based analysis. This paper explores the merits and shortcomings of each of these design approaches, and provides recommendations for fatigue-life validation of endovascular implants.
Full-text version of the journal article is available on-line (subscription required).