UMAT for SMA material 2

[VlasisDimo]

Hello

I try to write a UMAT subroutine for shape memory alloy material.

Does anyone have a UMAT subroutine for SMA material? In order to understand how I have to write mine. Could anyone help me please?
Any help is welcome.
Thanks.

 

[FEA way]

What kind of SMA material do you want to use ? Abaqus features built-in model for Nitinol and similar materials.

 

[VlasisDimo]

Do you mean the superelasticity material model of abaqus 2017?
I wish to understand the form of a SMA's UMAT subroutine and then choose a SMA material.

 

[IceBreakerSours]

Do you have a novel mathematical formulation for the superelastic behavior of SMAs? If yes, then a UMAT would be necessary. Otherwise, why not simply use the supported SMA material model? It's nothing more than a curve fit.

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[VlasisDimo]

That's right. I wish to modify the mathematical formulation of the SMA. So I need code, even of a simple SMA, in order to understand the form of the code. Any help is welcome.
However, the supported SMA material model of abaqus there is only in abaqus 2017 and newer versions, not in older, is't it ?

 

[FEA way]

That’s right, Nitinol is available as built-in material model from 2017 version.

Unfortunately it’s hard to find full UMAT codes. Scientific articles usually dob’t share them. But you may find some exemplary UMATs for SMA materials in theses such as "Computational modeling of the directionally-dependent leaflet properties of a bileaflet mitral bioprosthesis" by J.W. Yu.

 

[IceBreakerSours]

Unless you have the math written out *and* your FORTRAN isn't rusty *and* have help in your team, I would not recommend writing code. Writing code is just the first step; you have to verify the implementation, usually there is some iteration involved during testing going from single element to multi-element tests to full scale models of interest. Up front, time is also spent on just installing software in its appropriate sequence! One option that might make the coding feasible is exploring Abaqus training in subroutines. Scheduling might be tricky. Talk to Abaqus.

Agree with previous response: UMATs are not easily found. There are some in the documentation. Some are also available online uploaded by a few academics and in dissertations.

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[VlasisDimo]

Thanks FEA way and IcebreakerSours. The paper looks great, I'll read it.
Do you know what are the disadvantages of the built-in material model of abaqus? Does it have fewer features than UMAT code?

 

[FEA way]

The superelasticity model available in Abaqus is based on the work of Auricchio and Taylor (1996,1997). You can read about its assumptions in Abaqus documentation. UMAT, on the other hand, will let you create your own material model with any constitutive law. It offers a lot of freedom but requires significant experience and effort to write.

 

[IceBreakerSours]

The supported material law in Abaqus is itself written as a UMAT. However, your previous remarks make me curious: If you are not aware of the "disadvantages of the built-in material model", then what makes you consider writing your own code? If you are starting from nothing, you may be looking at sinking in many months to a year or more of your life into this SMA coding business.

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[ibme]

Head over to GitHub and check out the following:

https://github.com/Aero-tomato/SMA-UMAT

 

[VlasisDimo]

IcebreakerSours, I have dealt with UMAT code in the past, I do not start from nothing, but superelasticity built-in material model is a new feature of abaqus, it is not included in the older versions, and now I am going to use it for the first time.
There are codes on the internet that do the same thing as the "elastic" material option of abaqus or the "plastic".
I wonder if there is somewhere the same for "superelasticity".
Thanks FEAway. Assumptions in abaqus documentation?
Does anyone know where I can find the abaqus documentation of the abaqus 2017 version?
I find only the 2016 version and the older ones.

ibme thanks for the code. I had seen it too, Probably is the only one on the internet. If you had a simpler code it would help me.

 

[FEA way]

Documentation for all recent versions of Abaqus (2016-2020) can be found on Dassault Systemes website: Support —> Documentation —> User Assistance —> Simulia. Of course you will have to log into your account to access it.