ABAQUS SMA modelling with super_elastic 1

[IMOTEC]

Hi,
I want to model simple SMA material. I searched many forum and i found i can do it with super elastic which is ABAQUS material model. And i used ABAQUS Standart with a very simple loading. But it gave error which "too many attempt made for this increment". Also I tried to decrease increment very little but it couldn't solve my problem. Please help me how can i do it. I attached .CAE file.

 

[IceBreakerSours]

[ul]
[li]This is the first time I have seen/heard anyone use "simple" and "SMA" in one sentence. SMAs are ANYTHING BUT 'simple'. The material model is as challenging as anything I have ever come across. It's mechanical testing is challenging. Nothing about the material is 'easy'.[/li]
[li]Coming to your question about the 'too many increments..', I have a question for you: how experienced are you with the FEM? If you are a beginner (which seems likely), then you shouldn't be playing with SMAs right off the bat.[/li]
[/ul]

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[IMOTEC]

I think you miss understood me bwcuse of my english. I want to say MY MODEL İS SİMPLE. Of course i know SMA modeling is a problem. I want to try an example which is about abaqus super elastic also used for SMA. For second question i used abaqus for 2 years, nearly beginner.

 

[IceBreakerSours]

'Too many increments.." is a symptom, if you will, of a cause. You need to investigate the cause of the symptom. What is causing the solver to spit out this message? When does it fail? Have you looked at the .STA file and did you notice anything interesting? Have you looked at the ODB?

There is some detective work that needs to be done before you zero in on the real cause (improper/insufficient constraints, contact, excessive distortion of elements, material instability, concentrated loads, etc.) of the non-convergence. Once you identify the cause, only then can you come up with a way to resolve it.

Are you new to this forum? If so, please read these FAQ:

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083

 

[IMOTEC]

In message file it say 'many elements distorded exexcively'. Also you see it from file which I attached before. It turned 5 iteration which is name 1U 2U 3U 4U 5U. After 5U it failed. İf i decrease minimum initial increment, it said same thing after 13U. My model is really simple. It's one side encastered and the load applied other side.

 

[rstupplebeen]

I would start by running the model with a known stable material model. Once you know that it does converge you know what to focus on. I hope this helps.

Rob Stupplebeen

http://www.optimaldevice.com

https://sites.google.com/site/robertkstupplebeen/

 

[IMOTEC]

I tried it for steel. So it run. No problem occured. But why the SMA model is not run. I didn't use any subroutine or something. I just used super elastic model. Also it said you should named it ABQ_SUPER_ELASTIC. But something went wrong.

 

[rstupplebeen]

I opened your CAE model and here is a running list of comments:
1. A point load is used. I'd suggest loading differently since you are causing a significant stress concentration. (this is likely the problem)
2. Try meshing with hexes instead of second order tets.
3. Is a 31 coefficient material model really required? I would start with very simple material models and slowly increase the complexity.
I hope this helps.
Rob

Rob Stupplebeen

http://www.optimaldevice.com

https://sites.google.com/site/robertkstupplebeen/

 

[IMOTEC]

Thank you for your suggestion. I will try all of them. My main porpuse is modelling NiTi alloy which is shape memory alloy. Because of that i used 31 coefficent material model.