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UMAT and UHYPER subroutines

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(@heri8berto)
Active Member
Joined: 12 years ago

Is anyone familiar with UMAT and UHYPER subroutines?

I have Stress (xx, yy, xy) vs Strain (%) data in which I want to define my own material for a certain region in my spine model. I want to it to behave like a hyperelastic material with a Mooney-Rivlin model.

I tried using *HYPERELASTIC with *BIAXIAL TEST DATA but it requires NLGEOM on (in which my model fails to converge). The only option is using UMAT with NLGEOM turned off.

Im new to subroutines, how do I start off?

Much help and advise is appreciated!

Thanks

kevin

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Posts: 24
(@marco)
Eminent Member
Joined: 15 years ago

If you need to use mooney-rivlin model, then I think it is better to use the built-in model with NLGEOM on. Could you post some more details if you use *HYPERELASTIC with *BIAXIAL TEST DATA?

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Posts: 2
(@robertherbe24)
New Member
Joined: 12 years ago

soooory, i am here for the first time,and i have very bad question, its how can i find the place where can i write my subroutine. have i write it in fortran befor open abaqus.
see you.

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Posts: 24
(@marco)
Eminent Member
Joined: 15 years ago

Yes, it is just a text file, you can write your umat code and then run your simulation with your code.

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