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Thermal Residual Stresses in Metal Ceramic Assemblies

Posted Feb 5, 2018, 9:18 p.m. EST Structural Mechanics Version 5.2 2 Replies

Jessy H.
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Hi, I am new to Comsol and I'm trying to simulate the resulting thermal stresses in a metal ceramic assembly. The temperature is reduced from 1065 degrees C to 20 degrees C. In the Simulation "with symmetry boundaries" I have no problem solving the simulation but in the simulation "without symmetry boundaries" I get an error message: Maximum number of Newton iterations reached Returned solution is not converged. In the Simulation "with symmetry boundaries" I have no boundary constraints but in the simulation "without symmetry boundaries" the boundary constraints are necessary but I don't know exactly how to set the constraints, because I want the assembly to be "free". I set the boundary constraints like it was shown in the tutorial "Thermal Initial Stresses in a Layered Plate" Is it possible to get nearly the same results in these two models? I need this because in the next step there won't be symmetry. Could you please help me with this? Thanks a lot. Sorry for the double attachements. I forgot to change the names of the files.

2 Replies Last Post Feb 6, 2018, 4:21 p.m. EST
Thomas Loose
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Posted: 6 years ago Feb 6, 2018, 10:21 a.m. EST

Hi Jessy,

in version 5.3a there is a Rigid Motion Suppression node under Domain Constraints.

Another possibility is to use a Fixed Constraint node in one point(3 degrees of freedom) and three Prescibed Displacements for the rotational degrees of freedom.

Example: fix the origin u0=0 in point 1 fix the rotation around the x-axis: choose point 3 on the y - axis and set the displacement in z direction u0z=0 fix the rotation around the y-axis: choose point 2 on the z - axis and set the displacement in x direction u0x=0 fix the rotation around the z-axis: choose point 21 on the x - axis and set the displacement in y direction u0y=0

Hope that helps,

Regards,

Thomas

Hi Jessy, in version 5.3a there is a *Rigid Motion Suppression* node under *Domain Constraints*. Another possibility is to use a *Fixed Constraint* node in one point(3 degrees of freedom) and three *Prescibed Displacements* for the rotational degrees of freedom. Example: fix the origin u0=0 in point 1 fix the rotation around the x-axis: choose point 3 on the y - axis and set the displacement in z direction u0z=0 fix the rotation around the y-axis: choose point 2 on the z - axis and set the displacement in x direction u0x=0 fix the rotation around the z-axis: choose point 21 on the x - axis and set the displacement in y direction u0y=0 Hope that helps, Regards, Thomas
Jessy H.
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Posted: 6 years ago Feb 6, 2018, 4:21 p.m. EST

Hi Thomas,

thank you for your answer. Both of your suggestions worked! Thanks a lot. But why do I get different results when I use the model only with symmetry boundaries?

Regards,

Jessy

Hi Thomas, thank you for your answer. Both of your suggestions worked! Thanks a lot. But why do I get different results when I use the model only with symmetry boundaries? Regards, Jessy

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