Accelerated fatigue assessment method for evaluation of nitinol material & process Changes

Authors:

Fei Zhou, Edwards Lifesciences

Qin Yu, Edwards Lifesciences

Dhiraj Catoor, Edwards Lifesciences

Nitin Sharma, Edwards Lifesciences

Title:

Accelerated fatigue assessment method for evaluation of nitinol material & process Changes

Nitinol fatigue resistance assessment for quantifying structural heart implant durability and design safety margin requires testing hundreds of specimens to 600 million cycles or 15 years of implant life. Because Nitinol fatigue is sensitive to processing and material grades, material and process innovation to improve implant performance requires fatigue reassessment. Thus, fatigue testing presents a significant barrier to innovation and for adopting alternative materials to improve performance or to mitigate supply risks.

In this work, we aim to develop an accelerated approach utilizing shorter cycle fatigue test data (e.g., 200 million). We derive Weibull life distribution models from 600M cycle life data. We then right censor these data at shorter cycles and derive new life distribution models. Subsequently, we compare the fatigue strength and Weibull parameters for the full vs right censored data in order to assess feasibility of shorter cycle testing.