Nitinol Beam

[FarbodSeda]

Hi everybody,
I have modeled a cantilever beam with material properties of Nitinol, in Abaqus CAE.(VUMAT)
There is a displacement control and pushes the end of the beam downward.
In the first step the BC is exerted and then in the second one, it is released.
The simulation works well by any material. But it exhibits a strange response when nitinol is used.(It seems that the elements are decomposed)
Any idea is appreciated.

 

[IRstuff]

I'm not sure why you would even use Nitinol as a material for a beam, since its raison d'etre is as a shape-memory material. It's not intended to be structural at all.

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[BiPolarMoment]

@IRStuff

Slightly off topic: This isn't entirely true; Nitinol is occasionally used in the super-elastic state for implants that require a larger range of strain than can be provided by titanium (or SS or CoCr...) alloys.

 

[IRstuff]

Understood, but that does not appear to be what the OP was trying to do. Otherwise, there would be a known difference between the behavior of Nitinol vs. other materials.

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[FarbodSeda]

Yes, you are all right.
But this is a simplified version of my question.
My actual problem is a stent. When the stent is crimped (compacted) the behavior of Nitinol is fine. But when it is released, it's elements detach and the stent explodes.
So to check Nitinol response, I decided to model a simple cantilever beam in Nitinol.
I had the same problem. Any other material works fine.
Any idea?

 

[IRstuff]

So, basically, this is an Abaqus, and not a Nitinol nor biomechanics question?

You should red flag this posting and re-post in the Abaqus forum

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[IceBreakerSours]

I agree with IRstuff. It seems your question has little to do with biomechanics and more to do with FEA/Abaqus.

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