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Simulation of Ram bending of a pipe

Posted 7 oct. 2019, 12:56 UTC−4 Structural & Acoustics, Structural Mechanics 6 Replies

Ammad Yousuf
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I want to study effect of ram bending of a pipe (as shown in attched image) using FEA on comsol. This will be a static structural plastic deformation using elastoplastic material properties. If anyone could guide me how to model and approach this problem in comsol, it would be really helpful.

6 Replies Last Post 14 oct. 2019, 02:26 UTC−4
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago 7 oct. 2019, 14:50 UTC−4
Updated: 5 years ago 7 oct. 2019, 14:50 UTC−4

Check out this model (although it is in 2D):

https://www.comsol.com/model/compression-of-an-elastoplastic-pipe-12691

Regards,
Henrik

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Henrik Sönnerlind
COMSOL
Check out this model (although it is in 2D): Regards, Henrik
Ammad Yousuf
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Posted: 5 years ago 8 oct. 2019, 13:24 UTC−4

Check out this model (although it is in 2D):

Regards,
Henrik

Thank you for your reply and feedback. I had actually consulted this model, but as you said its a 2D model. I want study the stresses on extrados and intrados of pipe at bend and wall deformation at bend. I have defined the model as shown in picture attached. Assigned elastoplastic steel properties to the pipe and set large plasticity. Input defined displacement of the ram. Constrained the bobbins as fixed. The simulation terminates with an error. I think the model is not constrained properly and more over its still complex.

Regards, Ammad

>Check out this model (although it is in 2D): > > > >Regards, >Henrik Thank you for your reply and feedback. I had actually consulted this model, but as you said its a 2D model. I want study the stresses on extrados and intrados of pipe at bend and wall deformation at bend. I have defined the model as shown in picture attached. Assigned elastoplastic steel properties to the pipe and set large plasticity. Input defined displacement of the ram. Constrained the bobbins as fixed. The simulation terminates with an error. I think the model is not constrained properly and more over its still complex. Regards, Ammad

Attachments:

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 5 years ago 9 oct. 2019, 10:37 UTC−4

Hi

As your problem is symmetric I would propose to "cut" it in two with a symmetry plane to restrict any motion along the initial tube axis, and then to be sure you allow a sliding of the contact pair. In this way you have only one contact pair and less convergence issues.

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Have fun COMSOLing,
Sincerely,
Ivar
Hi As your problem is symmetric I would propose to "cut" it in two with a symmetry plane to restrict any motion along the initial tube axis, and then to be sure you allow a sliding of the contact pair. In this way you have only one contact pair and less convergence issues.
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago 9 oct. 2019, 11:03 UTC−4
Updated: 5 years ago 9 oct. 2019, 11:03 UTC−4

Actually, it seems to me like there are two symmetry planes, so that the model can be cut in one quarter. In addition to making your model run a factor of 20 or so faster, the symmetry conditions will provide a number of useful constraints as Ivar points out. You will however probably still need to attach a weak spring in the y-direction to the pipe to keep it stable before the contact solution has settled.

Regards,
Henrik

-------------------
Henrik Sönnerlind
COMSOL
Actually, it seems to me like there are two symmetry planes, so that the model can be cut in one quarter. In addition to making your model run a factor of 20 or so faster, the symmetry conditions will provide a number of useful constraints as Ivar points out. You will however probably still need to attach a weak spring in the y-direction to the pipe to keep it stable before the contact solution has settled. Regards, Henrik
Ammad Yousuf
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Posted: 5 years ago 11 oct. 2019, 10:53 UTC−4

Actually, it seems to me like there are two symmetry planes, so that the model can be cut in one quarter. In addition to making your model run a factor of 20 or so faster, the symmetry conditions will provide a number of useful constraints as Ivar points out. You will however probably still need to attach a weak spring in the y-direction to the pipe to keep it stable before the contact solution has settled.

Regards,
Henrik

Thank you for guidance. One symmetry plane is obvious i.e. YZ plane. By second symmetry plane do you mean XY plane (referring to the screenshot of my comsol model).

Regards, Ammad.

>Actually, it seems to me like there are two symmetry planes, so that the model can be cut in one quarter. In addition to making your model run a factor of 20 or so faster, the symmetry conditions will provide a number of useful constraints as Ivar points out. You will however probably still need to attach a weak spring in the y-direction to the pipe to keep it stable before the contact solution has settled. > >Regards, >Henrik Thank you for guidance. One symmetry plane is obvious i.e. YZ plane. By second symmetry plane do you mean XY plane (referring to the screenshot of my comsol model). Regards, Ammad.
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago 14 oct. 2019, 02:26 UTC−4
Updated: 5 years ago 14 oct. 2019, 02:27 UTC−4

Yes, I was referring to the XY plane.

Regards,
Henrik

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Henrik Sönnerlind
COMSOL
Yes, I was referring to the XY plane. Regards, Henrik

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