Keeping stress triaxiality constant for a cube RVE with void

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Keeping stress triaxiality constant for a cube RVE with void

Abaqus Users mailing list
Dear All,
 

 I am trying to study the void growth in a cube RVE containing the void at the center. For the analysis to be valid, I need the volume averaged or resultant stress triaxiality to be constant. I am using a UMAT subroutine for the material parameters. For boundary conditions I am using displacements on the faces of the cube. To apply the required triaxiality, I am applying the displacements in a fixed ratio in the three directions. But as the void grows, the response of the cube becomes softer and the volume averaged triaxiality hikes up which gives unrealistic results of void growth.
I hope I am making sense here. But if someone here knows how to keep the resultant stress triaxiality constant with UMAT and 3D cube, please advise how to achieve that.

Thank you in anticipation.

Regards,
Umair

P.S. I tried to search in threads for this topic but I couldn't find one. If this query was answered before please direct me to the answer and sorry for the inconvenience.  
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Re: Keeping stress triaxiality constant for a cube RVE with void

Abaqus Users mailing list
Is it possible to measure the current triaxiality during the
simulation (for example using subroutine UEXTERNALDB)? You could then
use this info to adjust the displacements, for example using a user
subroutine for the displacment (communicationg the stress values via a
common block).


> Dear All,
>
>
> I am trying to study the void growth in a cube RVE containing the void at the center. For the analysis to be valid, I need the volume averaged or resultant stress triaxiality to be constant. I am using a UMAT subroutine for the material parameters. For boundary conditions I am using displacements on the faces of the cube. To apply the required triaxiality, I am applying the displacements in a fixed ratio in the three directions. But as the void grows, the response of the cube becomes softer and the volume averaged triaxiality hikes up which gives unrealistic results of void growth.
> I hope I am making sense here. But if someone here knows how to keep the resultant stress triaxiality constant with UMAT and 3D cube, please advise how to achieve that.
>
> Thank you in anticipation.
>
> Regards,
> Umair
>
> P.S. I tried to search in threads for this topic but I couldn't find one. If this query was answered before please direct me to the answer and sorry for the inconvenience.
>


                    Priv.-Doz. Dr. Martin Bäker
                    Institut für Werkstoffe
                    Technische Universität Braunschweig
                    Langer Kamp 8
                    38106 Braunschweig
                    Germany
                    Tel.: 00-49-531-391-3065
                    Fax   00-49-531-391-3058
                    e-mail <[hidden email]>
    http://www.tu-braunschweig.de/ifw/institut/mitarbeiter/baeker
                  http://www.scienceblogs.de/hier-wohnen-drachen


[Non-text portions of this message have been removed]


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Re: Keeping stress triaxiality constant for a cube RVE with void

Abaqus Users mailing list
Thank you for your valuable input. I have managed to achieve the desired results by using MPC constraints along with spring elements. If anyone ever need help with the same problem, I'll be more than happy to help.


Regards,
Umair




________________________________
From: [hidden email] <[hidden email]> on behalf of Martin Baeker [hidden email] [Abaqus] <[hidden email]>
Sent: Wednesday, February 8, 2017 4:49 PM
To: [hidden email]
Subject: Re: [Abaqus] Keeping stress triaxiality constant for a cube RVE with void






Is it possible to measure the current triaxiality during the
simulation (for example using subroutine UEXTERNALDB)? You could then
use this info to adjust the displacements, for example using a user
subroutine for the displacment (communicationg the stress values via a
common block).


> Dear All,
>
>
> I am trying to study the void growth in a cube RVE containing the void at the center. For the analysis to be valid, I need the volume averaged or resultant stress triaxiality to be constant. I am using a UMAT subroutine for the material parameters. For boundary conditions I am using displacements on the faces of the cube. To apply the required triaxiality, I am applying the displacements in a fixed ratio in the three directions. But as the void grows, the response of the cube becomes softer and the volume averaged triaxiality hikes up which gives unrealistic results of void growth.
> I hope I am making sense here. But if someone here knows how to keep the resultant stress triaxiality constant with UMAT and 3D cube, please advise how to achieve that.
>
> Thank you in anticipation.
>
> Regards,
> Umair
>
> P.S. I tried to search in threads for this topic but I couldn't find one. If this query was answered before please direct me to the answer and sorry for the inconvenience.
>


Priv.-Doz. Dr. Martin Bäker
Institut für Werkstoffe
Technische Universität Braunschweig
Langer Kamp 8
38106 Braunschweig
Germany
Tel.: 00-49-531-391-3065
Fax 00-49-531-391-3058
e-mail <[hidden email]>
http://www.tu-braunschweig.de/ifw/institut/mitarbeiter/baeker
http://www.scienceblogs.de/hier-wohnen-drachen


[Non-text portions of this message have been removed]






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Re: Keeping stress triaxiality constant for a cube RVE with void

areejvk
This post has NOT been accepted by the mailing list yet.
Hello,
I am also working on a similar problem. Can you please explain the subroutine code?
Thanks,
Areej
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