Dear all,

 I'm new in imechanica. I need some informations about VUMAT for Nitinol. I would like to implement in fortran a subroutine for the behaviour of shape memory alloy.I looked for some subroutines already implemented but they have been developed in the implicit way.

It's true that with the VUMAT(explicit) I could have some problems of stability and convergence.Could someone suggest me any reason to make this model in the VUMAT?I know that in VUMAT I can't redifine the time increment so before running the analysis It's important to pay attention on Dt.

Is it better for dynamics analysis or for coupling with CFD software like FLUENT?

HI, 

I'm just wondering if anyone knows if there are any guidelines/references on the maximum strain in a Nitinol component during a shape setting heat treatment.  

Regards,

Offshore 

An Introduction to the Unique Material Properties of Nitinol

Follow this link to the details of the coming ASME webnar.

http://catalog.asme.org/Education/Webinar/Nitinol_Webinar.cfm

Xiao-Yan Gong, PhD

Stent and Nitinol have revolutionized the medicine.  In past decades, guidewires, stents, filters and many minimumly invasive devices and implants are made of Nitinol and they proved to be very successful.

However, the fatigue behavior of Nitinol has not been well understood.  As a consequences, many stent fractures have been observed in-vivo.  Below is a list of misconcepts that may contribute to the widely observed in-vivo fractures on Nitinol stents: