Coupled Temperature-Displacement Analysis Converging

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Coupled Temperature-Displacement Analysis Converging

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Hello

I'm using a coupled temperature-displacement step including SMA (Shape Memory Alloy) UMAT. It works properly in low rate of mechanical loadings but diverges in hi rates. For example if I define step time=10 it converges but in step time=1 it diverges with the error of "Too many attempts made..".
I also have tried smaller increments but no difference was made in diverging.
I've found that I can affect on converging by changing the tolerances of solving equations which is defined in ABAQUS solving options. Is there anybody familiar with this problem or changing the tolerances in the right way?

Thanks
yadollah
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Re: Coupled Temperature-Displacement Analysis Converging

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Change the controls that affect the solution process (like number of
iterations etc., for example, use Analysis=discontinuous).


DO NOT touch the residual tolerances unless you know exactly what you are doing.


I would also recommend to find out what exactly changes in th emodel
if you increase the loading speed if this is responsible for your
problem. Usually, convergence problems have a reason that can be
understood and removed.




> Hello
>
> I'm using a coupled temperature-displacement step including SMA (Shape Memory Alloy) UMAT. It works properly in low rate of mechanical loadings but diverges in hi rates. For example if I define step time=10 it converges but in step time=1 it diverges with the error of "Too many attempts made..".
> I also have tried smaller increments but no difference was made in diverging.
> I've found that I can affect on converging by changing the tolerances of solving equations which is defined in ABAQUS solving options. Is there anybody familiar with this problem or changing the tolerances in the right way?
>
> Thanks
> yadollah


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Re: Coupled Temperature-Displacement Analysis Converging

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No need for UMAT:


http://imechanica.org/node/18733


http://imechanica.org/node/18476




Frank






Am 10.05.2017 um 09:05 schrieb [hidden email] [Abaqus]:

>
> Hello
>
> I'm using a coupled temperature-displacement step including SMA (Shape
> Memory Alloy) UMAT. It works properly in low rate of mechanical
> loadings but diverges in hi rates. For example if I define step
> time=10 it converges but in step time=1 it diverges with the error of
> "Too many attempts made..".
> I also have tried smaller increments but no difference was made in
> diverging.
> I've found that I can affect on converging by changing the tolerances
> of solving equations which is defined in ABAQUS solving options. Is
> there anybody familiar with this problem or changing the tolerances in
> the right way?
>
> Thanks
> yadollah
>
>


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Re: Coupled Temperature-Displacement Analysis Converging

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In reply to this post by Abaqus Users mailing list
I have got similar error many times. Many a time the error is becuase of
mismatch between part model dimensions (e.g. dimensions in mm) and units of
the material property (e.g. thermal diffusivity specified as m2/sec.). I
would recommend mutiplying thermal conductivity by 0.000001 to counter such
an issue.


On Wed, May 10, 2017 at 12:35 PM, [hidden email] [Abaqus] <
[hidden email]> wrote:


>
>
> Hello
>
> I'm using a coupled temperature-displacement step including SMA (Shape
> Memory Alloy) UMAT. It works properly in low rate of mechanical loadings
> but diverges in hi rates. For example if I define step time=10 it converges
> but in step time=1 it diverges with the error of "Too many attempts made..".
> I also have tried smaller increments but no difference was made in
> diverging.
> I've found that I can affect on converging by changing the tolerances of
> solving equations which is defined in ABAQUS solving options. Is there
> anybody familiar with this problem or changing the tolerances in the right
> way?
>
> Thanks
> yadollah
>
>
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