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Axes!
Idiots' guide please (I have looked at the manual). The local UVW axes are the ones that show up inside the elements when I hit 'Show element axes', correct? The manual says that U follows nodes 1 & 2, but I have seen somewhere that local axes follow the global axes by default. The latter seems to be so, as element axes all seem to align naturally throughout a model, even when manual meshing, as long as the node sequence leads to normal looking elements.
Even when all local axes look the same, I have had erratic results form 'Refine Custom', with different elements refining differently even when they are, apparently, identically oriented. What exactly are R, S, T axes and how do they relate to X, Y, Z and U, V, W?
I need to understand this as nearly all of my meshing is manual, and I want to use some orthotropic properties. Thanks all, in anticipation. As mentioned, idiots' guide is good, or links. Knowledge is power!
Dave
Even when all local axes look the same, I have had erratic results form 'Refine Custom', with different elements refining differently even when they are, apparently, identically oriented. What exactly are R, S, T axes and how do they relate to X, Y, Z and U, V, W?
I need to understand this as nearly all of my meshing is manual, and I want to use some orthotropic properties. Thanks all, in anticipation. As mentioned, idiots' guide is good, or links. Knowledge is power!
Dave
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Comments
Beams: U axis is from node 1 to node 2. V and W are adjustable.
Shells: W axis is the shell normal. U and V are adjustable. U defaults to being along the face 1 edge (nodes 1-2 for tri3/quad4 and nodes 1-3 for tri6/quad8/quad9).
Solids: U, V, W are all adjustable and default to the global X, Y, Z directions as you've seen.
For beams and orthotropic shells you should always set the axes explicitly because the defaults are arbitrary and probably not what you'll want.
R,S,T in refine custom are really sets of edges defined by the node numbering and you can't adjust them. It's not really reliable to use U,V,W or X,Y,Z for this because the refinement is only possible along the element edges regardless of how it's oriented or distorted. Unfortunately, as you've seen, it gets difficult when the local node numbering is different on each element in a mesh so you have to refine them separately in those cases. This is something I'd like to improve in future. It's hard to describe which direction is which, so I usually just use trial and error to see which one refines in which direction. If you set U, V, W explicitly, then using refine custom won't alter that.
See attached picture.