How to model a beam on elastic foundation?

asceduardoasceduardo Member
edited August 2020 in Structures

I am trying to model a simply-supported beam on elastic foundation, kind of like the figure below:

So far, I have not been able to properly model the elastic foundation. I know that Ansys has an "Elastic Support" feature for 2D and 3D structures [N/m³]. However, I need it to be applied along the beam, that is, at an edge [N/m²]. I can think of two possible solutions (which I could not successfully apply yet):

1) To model an elastic support at an edge, so that Ansys will automatically distribute the stiffness at nodes. This is the best option, as I would not need to manually adjust the stiffness factor according to the mesh density.

2) To define springs (or bushing joints), one by one, at each node. This solution is inconvenient, since it would require me to individually define hundreds of "Named Selections" and "Connections", and to adjust the stiffness factor for each connection.

That being said, my question is: is there any way to define an Elastic Support along an edge? If not, is there any way to efficiently define connections at a number of nodes (for example, using command lines or editing Ansys' data files)?

In case it helps, my Ansys file is below:


Best Answers

Answers

  • Your solution works for me, thank you. Anyway, let me ask you two more questions:

    1) In other FE softwares, we can modify the surface's standard thickness (in Z direction). However, in Mechanical APDL I could not find such an option anywhere. In SpaceClaim, I did find it, but it does not affect the final results at all. Since the results provided by Ansys' 2D Plane Strain model match with a beam with cross-section 0.5 x 1000 mm, I suppose the standard thickness is 1 m. Can I change that?

    2) Although your solution is very suitable for my particular objetive (which was to validate the analytical model of a beam on elastic support), I am still curious to know how can one efficiently define a large amount of instances (e.g.: loads, springs, concentrated masses etc). In other FE softwares, one can simply open the source file using, for example, Nodepad, and then manually write command lines to define such a large number of instances. What about in Ansys? How could I, let us say, define 100 springs, one for each node?

  • Thank you, that was exactly what I needed. As other users might have the same doubt in the future, I am here attaching a file with the modal analysis of three analogous models:

    1) A 2D surface under plane stress;

    2) A beam on elastic foundation (modelled with a set of springs);

    3) And a cylindrical shell (axisymmetric modes, analogous to the previous models via Timoshenko's analogy between beams on elastic foundation and cylindrical shells subjected to axisymmetric loads).

  • You can model the edge beam with Shell 63.

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