Getting integration points on element nodes

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Hello,

I am looking for a way to get integration points at my element nodes. This is needed to get a more stable third medium contact model. You can find the explanation for it in this paper.

When not using COMSOL, I usually resort to Newton–Cotes quadrature rules or Gauss-Lobatto quadrature, which are both very standard methods. However, I couldn't find these anywhere in the documentation; it seems that only the standard Gaussian quadrature is available. Simply increasing the number of standard Gauss integration points, in order to get some of the points closer to the element nodes, is computationally very inefficient and does not provide the stability that I am looking for. Getting Newton–Cotes or Gauss-Lobatto to work in COMSOL seems like something that, in theory, should be very easy to implement; it is just a matter of defining points and assigning them weights.

Any approach to achieve this when using Q4, Q8, Q9, or LST elements in 2D (or their equivalent in 3D) is highly appreciated.

/Andreas


3 Replies Last Post Mar 11, 2025, 4:58 a.m. EDT

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Posted: 4 weeks ago Mar 7, 2025, 3:56 a.m. EST

For reference, I am trying to solve the C-shape benchmark problem for third medium contact, as shown in this video:

For reference, I am trying to solve the C-shape benchmark problem for third medium contact, as shown in this video:


Acculution ApS Certified Consultant

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Posted: 4 weeks ago Mar 7, 2025, 5:30 a.m. EST

Not my field at all, I am sure Henrik or somebody else from COMSOL can answer. Just want to mention that I am pretty sure that the G-L integration is used for the Time-Explicit DG-FEM numerical scheme in COMSOL, so it is 'in there' for some physics. Anyway, wait for a real expert in the field for a proper answer ;-)

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René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
Not my field at all, I am sure Henrik or somebody else from COMSOL can answer. Just want to mention that I am pretty sure that the G-L integration is used for the Time-Explicit DG-FEM numerical scheme in COMSOL, so it is 'in there' for some physics. Anyway, wait for a real expert in the field for a proper answer ;-)

Henrik Sönnerlind COMSOL Employee

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Posted: 3 weeks ago Mar 11, 2025, 4:58 a.m. EDT
Updated: 3 weeks ago Mar 12, 2025, 9:02 a.m. EDT

There is (currently) no way for the user to specify other integration rules than standard Gauss integration. The Gauss-Lobatto integration that René mentions is hardwired at a level that is not accessible using the standard API.

The suggestion is interesting, though.

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Henrik Sönnerlind
COMSOL
There is (currently) no way for the user to specify other integration rules than standard Gauss integration. The Gauss-Lobatto integration that René mentions is hardwired at a level that is not accessible using the standard API. The suggestion is interesting, though.

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