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Confusing error message for: Rollers on a beam.

Posted Dec 7, 2022, 5:14 a.m. EST Studies & Solvers, Structural Mechanics Version 5.6 3 Replies

Amber Labuz
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Hey,

I am creating a model of how a bone will react under different loads from a 4-point bending. The model has been created as a 2D model where the geometry and material properties are set to that of the bone, and the model works when the ends are fixed constraints. I am solving the problem in solid mechanics as a stationery study where the solution is solved using a parametric sweep.

However, I want to change the fixed constraints to roller, as I am validating the model using a 4-pont bending in a lab where the moulded ends are on rollers. When I set the ends of the rectangle to be on rollers in comsol the following error message appear:

Feature: Stationary Solver 1 (soll/s1) Failed to find a solution. The relative residual (0.0093) is greater than the relative tolerance. There was a warning message from the linear solver. Iterative refinement triggered. The returned solution is not converged. Not all parameter steps returned.

Does anyone know how I can solve this problem? I have attached the model below and am hoping someone could explain how to fix it.

Thank you in advance!

Attachments:

3 Replies Last Post Dec 12, 2022, 11:28 a.m. EST
Kristian Rye Jensen COMSOL Employee

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Posted: 2 years ago Dec 7, 2022, 5:25 a.m. EST

Dear Amber Labuz,

Thank you for posting on the Discussion Forum.

When you have a roller condition instead of a fixed condition and you have a load, there are nothing to stop the movement, so it will go on indefinitely in the y-direction.

There will be an infinity of solutions, that's why it doesn't converge.

If you have further questions, you can use the technical support through support@comsol.com.

Hope this helps.

Best regards,

Kristian Rye Jensen

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Kristian Rye Jensen
COMSOL DK
Dear Amber Labuz, Thank you for posting on the Discussion Forum. When you have a roller condition instead of a fixed condition and you have a load, there are nothing to stop the movement, so it will go on indefinitely in the y-direction. There will be an infinity of solutions, that's why it doesn't converge. If you have further questions, you can use the technical support through support@comsol.com. Hope this helps. Best regards, Kristian Rye Jensen
Amber Labuz
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Posted: 2 years ago Dec 12, 2022, 11:19 a.m. EST

Hey Kristian,

Thank you for the reply, i have tried contacting the support email but have not gotten any reply. Is there another way i can add mechincal support rollers onto my model?

Best Amber

Hey Kristian, Thank you for the reply, i have tried contacting the support email but have not gotten any reply. Is there another way i can add mechincal support rollers onto my model? Best Amber
Jeff Hiller COMSOL Employee

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Posted: 2 years ago Dec 12, 2022, 11:28 a.m. EST

Hello Amber,

The support team sent you a response on December 9 (three days ago). Please check your Access account / email.

Best,

Jeff

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Jeff Hiller
Hello Amber, The support team sent you a response on December 9 (three days ago). Please check your Access account / email. Best, Jeff

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