Learning Forum

[f.yasmin]

Hi there,

I am currently performing stress analysis on a Nitinol self-expanding stent, following the guidelines provided in the course found at https://learninghub.ansys.com/learn/courses/574/self-expanding-stents. I successfully replicated the entire model (see Fig. 1). 

However, when modeling my own different geometries using only the crimping analysis module, I am encountering an issue where the von Mises stress reaches a value of 2451 MPa, which is unexpectedly high 👇.

Despite this, both the equivalent plastic strain and elastic strain are within the acceptable range of 5-7%. Could you please advise if this might be an issue related to my geometry or a potential contact-related problem or any other else?

I would greatly appreciate your insight on this matter.

Kind regards,
Farhana Yasmin

[Kaushal Vadnere]

Hello,
What is the location of highest magnitude of Eq. VMS in your model? is it over a larger area or on a single node/element? can you attach a screeshot?

The reason I am asking is, this seems like a case of artificially high stress or stress singularity. Artificially high stresses arise in structural FEA model due to variety of reasons such as sharp corners in contact, over-oconstraint, etc. Also, you are using a hyperelastic material model which makes the analysis highly non-linear. You can refer to 'lesson 3 - understanding and dealing with artificially high stress' in this free Ansys Innovation course: Numerically Accurate Results - Innovation Space (ansys.com) to understand how to deal with stress singularities.

Thanks