Forces in unrestrained beam exposed to increasing temp.

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kisfaludi
Posts: 5
Joined: Fri Sep 21, 2018 3:23 am
Location: Technical University of Denmark

Forces in unrestrained beam exposed to increasing temp.

Post by kisfaludi » Sun Oct 28, 2018 8:22 am

Hi,

I am facing an issue with the thermal model and would be gratefull if someone could help me with it.

When I run a increasing temperature uniformly on a simply supported beam(pinned on one side, rolling support on the other) I get a small axial force in the beam. There are no forces applied on the beam. The beam should be moving freely. I get this for a script developed by me and also when I download and run the following example by removing the translational spring: https://www.wiki.ed.ac.uk/display/opens ... conditions

Could someone please give an explanation why we have a force in the beam, while there should not be? I have noticed that the magnitude of the force depends on the size of the step. If fine increments are used for the temperature than the forces are small and they increase linearly with the increment of the step size.

Thank you for your help,
Zoltan

kisfaludi
Posts: 5
Joined: Fri Sep 21, 2018 3:23 am
Location: Technical University of Denmark

Re: Forces in unrestrained beam exposed to increasing temp.

Post by kisfaludi » Sun Oct 28, 2018 8:41 am

I should mention that the expnasion of the beam is consistent with the analytical solutions. Furthermore, if I run a problem with uniform gravity loads and restarined boundary conditions, the results are fine, as expected from hand calculations. Therefore, the issue is only for the unrestrained case when no axial forces should appear at all.

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