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# degrees of freedom in truss interface

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Hi all,

I´m starting to work with matlab + comsol. In order to do some practice, I simulated a simple 2D truss structure (see attached file) and I got surprised by the "degrees of freedom solved for" in COMSOL. As it has only one mesh-element per node and a total of 5 nodes, I was expecting to have 5 nodes * 2 dof / node = 10 dof. But COMSOL is solving for 22 dof's.

Does anyone can help me understand what are these extra dof's?

Thanks in advance,
Andre


1 Reply Last Post Jul 29, 2010, 5:45 p.m. EDT

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Posted: 1 decade ago Jul 29, 2010, 5:45 p.m. EDT
Hi,

I think I figured out this question. By default COMSOL uses quadratic shlag elements and that's why I got more dof than I was expecting.

After reading the folowing post:

www.comsol.co.in/community/forums/general/thread/5351/

I learned how to change the element order to 1 (linear) and by doing so I finally got a total of 10 dof, which allows me to compare the results with my analytical solution.

Thanks,
Hi, I think I figured out this question. By default COMSOL uses quadratic shlag elements and that's why I got more dof than I was expecting. After reading the folowing post: http://www.comsol.co.in/community/forums/general/thread/5351/ I learned how to change the element order to 1 (linear) and by doing so I finally got a total of 10 dof, which allows me to compare the results with my analytical solution. Thanks,

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