Principal Force Vectors

Hi everyone,

In your experience, is there a straightforward to extract from Karamba structural results at the nodes of a shell element rather than at its center?

I'm particularly wondering about principal force directions since at times they cannot be accurately interpolated, for instance, from directly averaging the force directions at its neighbors.

I presume this might have to be retrieved directly from the feb.

Thanks, Rafael

Replies to This Discussion

Permalink Reply by Karamba3D on July 23, 2018 at 1:28pm

Hi Rafael,

in Karamba all shell forces are calculated at the element centroids. The values at the nodes are calculated as a weighted average of the neighboring elements. The weight of each element is the elements opening angle divided by the sum of all element angles at a node.

The reason for this procedure is, that at the boundaries of the shell elements stress dicontinuities exist. These are due to the chosen Finite Element discretisation. So at the nodes no smooth stress conditions exist.

In case that the shell mesh is too coarse principal force directions may change considerably from node to neighboring node. Try to refine the mesh in order to avoid that.

Best,

Clemens

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