Nitinol as a material is often considered thermodynamically stable at temperatures below 100 °C since these temperatures are significantly lower than the homologous temperature range of (0.3–0.5) Tm (Tm = absolute melting temperature) at which viscoplastic phenomena become active. However, when considering a stent-type device constrained in a catheter, factors such as the peak strain and the associated stress coupled with the exposed temperature and time may have a significant impact on the mechanical behavior of a nitinol component. This can impact the performance (e.g., the recovery) of a constrained device. This effort investigates the effect of applied strain at various test temperatures and exposure times on the unloading response of straight nitinol wires and apical geometries.
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