User Implemented Nitinol Material Model in ANSYS
Nitinol is an acronym for NIckel TItanium Naval Ordinance Laboratory since the alloy was originally developed at the Naval Lab. It is used to describe a family of materials, which contain a nearly equal mixture of nickel and titanium. Nitinol alloys are attractive to the medical device industry because they are biocompatible and when processed correctly, are at their optimum superelastic behavior at body temperature. Nitinol exhibits a different stress-strain curve for loading and unloading that cannot be modeled with existing material models in ANSYS. This paper describes the implementation of a unique user material model in ANSYS that simulates the nitinol superelastic behavior. Example analyses are provided demonstrating the application of this material model for medical implant devices called stents.