I'm having troubble constraining the rotational DOF (of an RBE2 reference node) in an axisymmetric analysis. First I noticed that Mentat just ignored this request, just applying the translational constraint on the node; then, after manually editing the .dat file to what I believe should be the correct form of the FIXED DISP card, I still couldn't make Marc actually constrain it (from the .out file I see that only the translational DOF is constrained). Following is the 3rd to 10th block of the FIXED DISP card (excl. blocks 6 & 7) that I tried:
Then I tried constraining all the rotational DOFs, in case there would be some convention regarding the (single) rot DOF in an axisymmetric analysis, viz.
Still, the .out file tells me I'm just constraining DOF 1...
I have successfully constrained the rotational DOF in Marc in 3d analyses, so I know that is possible; is it not possible to do the same in axisymmetric analyses?
Well, if you want to constrain a surface (an edge in the 2d axisymmetric modelling space) from rotating, you need to constrain that DOF...
It's true you don't have to constrain the y/r direction (since displacement in that direction requires work, ie. induces strain energy), but that does not mean those DOFs will remain zero.
When there is a possibility for displacements in two directions (i.e. in a plane), there's possibility for rotation, which one could want to constrain.
I don't follow your implication from not having to fix Ydof => no need to constrain rot Z dof. Am I missing something..?
Well, if you want to constrain a surface (an edge in the 2d axisymmetric modelling space) from rotating, you need to constrain that DOF...
It's true you don't have to constrain the y/r direction (since displacement in that direction requires work, ie. induces strain energy), but that does not mean those DOFs will remain zero.
When there is a possibility for displacements in two directions (i.e. in a plane), there's possibility for rotation, which one could want to constrain.
I don't follow your implication from not having to fix Ydof => no need to constrain rot Z dof. Am I missing something..?