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Buckling of Euler beam under fixed-pinned boundary condition...
Posted Sep 7, 2010, 2:23 p.m. EDT 1 Reply
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I am trying to model buckling of a fixed-pined beam which there is a specific displacement at the pinned end. While for the 2D it works well. I faced difficulty when I want to run the 3D model.
I have attached the file for the 3D model. One end is fixed and one of the points on the other end has a specified displacement. While the deflection configuration looks reasonable, the pinned end deformation is not something that I expected. The beam at the pinned end has an ellipsoid cross-section.
I should note that the scaling factor for the deformed shape is 1. For smaller scaling factors you cannot see the ellipsoidal cross-section of the material.
I have attached the file for the 3D model. One end is fixed and one of the points on the other end has a specified displacement. While the deflection configuration looks reasonable, the pinned end deformation is not something that I expected. The beam at the pinned end has an ellipsoid cross-section.
I should note that the scaling factor for the deformed shape is 1. For smaller scaling factors you cannot see the ellipsoidal cross-section of the material.
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1 Reply Last Post Sep 8, 2010, 1:50 a.m. EDT
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Posted:
1 decade ago
Hi
first of all you are using bulk 3D structural and not the "Euler beam models" this confused me in the beginning, as the Euler theory if I remember correctly is implemented in linear mode only (at least in 3.5, things might have changed in V4).
Then my comments on your model are:
1) update yourComsol to the latest "patch" see the main web site"
2) turn on the large deformation: <<Linear Elasttic Material Model node - Geoemtrical Non-linearity - ON >>
3) I tend to avoid "point" BC's as these are in fact "singularities, you can either apply forces and moments on the end surface, or enforce an average displacement of the full surface by calculating the mean U, V, W displacements of the end surface ()coupling integration/averages) and apply a prescribed displacement on these values
I'm not sure the overall buckling shape would change that much, but certainly the end surface would have another deformation.
You couls also check the reaction forces, and run a bucling eigenmode analysis to compare the results
--
Good luck
Ivar
first of all you are using bulk 3D structural and not the "Euler beam models" this confused me in the beginning, as the Euler theory if I remember correctly is implemented in linear mode only (at least in 3.5, things might have changed in V4).
Then my comments on your model are:
1) update yourComsol to the latest "patch" see the main web site"
2) turn on the large deformation: <<Linear Elasttic Material Model node - Geoemtrical Non-linearity - ON >>
3) I tend to avoid "point" BC's as these are in fact "singularities, you can either apply forces and moments on the end surface, or enforce an average displacement of the full surface by calculating the mean U, V, W displacements of the end surface ()coupling integration/averages) and apply a prescribed displacement on these values
I'm not sure the overall buckling shape would change that much, but certainly the end surface would have another deformation.
You couls also check the reaction forces, and run a bucling eigenmode analysis to compare the results
--
Good luck
Ivar