Potential distortion of FEA modeling results using ASTM conforming tensile test method

The accurate determination of materials properties is a crucial step in predicting the mechanical response of medical devices. Tensile testing per ASTM F2516-14 is one of the commonly used testing standards to generate input parameters for FEA modeling. Therefore, ASTM F2516-14 was implemented to generate sample geometry independent results by testing with a constant strain-rate for a given cross-sectional area. Here, medical grade Nitinol wires with a diameter of 0.5 mm were tested according to ASTM F2516-14 exhibiting a strong geometry dependence on the resultant mechanical properties. Furthermore, FEA modeling of a stent frame was conducted demonstrating the significance of geometry dependent tensile test results on load-displacement, strain and lifetime predictions. The microstructural phenomena behind these observations will be discussed and the solution presented to generate accurate and sample geometry independent tensile data.