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waviness in Mises stress distribution on the mechanic contact surface

Posted Jun 3, 2020, 9:57 a.m. EDT 2 Replies

Yun Deng
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I got a problem when simulating a process of compressing a piece of metal with a punch. As you can see in the figures, I applied a pressure on the upper punch, set fix constraint on the lower punch, the boundary condition for the sample/upper punch surface is mechanical contact, and the lower boundary of the sample is set to roller constraint.

Then I got a Mises stress on the contact surface to be very wavy, I wonder how to remove those waviness?

Best,

Yun Deng

2 Replies Last Post Jun 5, 2020, 9:22 a.m. EDT
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago Jun 3, 2020, 3:09 p.m. EDT

Hi,

Some suggestions:

  1. My first guess is that this is related to the mesh resolution. Check that you have a finer mesh on the destination side than on the source side.
  2. If you are using the penalty method, switch to augmented Lagrangian.
  3. Check that the solution is converged by reducing the tolerance.
  4. Plot solid.misesGp rather than solid.mises.
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Henrik Sönnerlind
COMSOL
Hi, Some suggestions: 1. My first guess is that this is related to the mesh resolution. Check that you have a finer mesh on the destination side than on the source side. 2. If you are using the penalty method, switch to augmented Lagrangian. 3. Check that the solution is converged by reducing the tolerance. 4. Plot solid.misesGp rather than solid.mises.
Yun Deng
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Posted: 5 years ago Jun 5, 2020, 9:22 a.m. EDT

Hi,

Some suggestions:

  1. My first guess is that this is related to the mesh resolution. Check that you have a finer mesh on the destination side than on the source side.
  2. If you are using the penalty method, switch to augmented Lagrangian.
  3. Check that the solution is converged by reducing the tolerance.
  4. Plot solid.misesGp rather than solid.mises.

Thank you Henrik,

I tried to use the augemented Lagrangian method, however, I always got the error message:

Nonlinear solver did not converge. No convergence, even when using the minimum damping factor. Time: 0 s. Last time step is not converged.

I tried to change the initial value, but without any sucess:( would you mind checking my model? Thank you!

Best,

Yun

>Hi, > >Some suggestions: > >1. My first guess is that this is related to the mesh resolution. Check that you have a finer mesh on the destination side than on the source side. >2. If you are using the penalty method, switch to augmented Lagrangian. >3. Check that the solution is converged by reducing the tolerance. >4. Plot solid.misesGp rather than solid.mises. Thank you Henrik, I tried to use the augemented Lagrangian method, however, I always got the error message: Nonlinear solver did not converge. No convergence, even when using the minimum damping factor. Time: 0 s. Last time step is not converged. I tried to change the initial value, but without any sucess:( would you mind checking my model? Thank you! Best, Yun

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