Comments

• disla

  October 30 edited October 30

  You need custom cards to do that.
  Reducing all DOFS of an aligned set of nodes to two, requires a rigid body definition of those nodes. (Good moment to remind Victor about this possible improvement )
  To keep them in an axis and all body free to rotate around that axis you need to set up the REF also aligned with the nodes.
  You also need to *Transform ref and rot nodes to cylindrical coordinates. Then constrain all Ref and Rot except z.
  Note the set of nodes will not be able to stretch in between them nor rotate as a whole if they are set up as rigid body.
  The most general case, you have a powerful nonlinear *MPC Straight card in ccx. Also needs custom set up. Check manual 7.91 *MPC
  
  NOTE: EDITED. Straight doesn't allow the nodes on the line to stretch and change distances in between them.
  
  NOTE: EDITED. Straight allow the nodes on the line to stretch and change distances in between them while keeping them aligned.
• Mag

  October 30

  Hi Disla,
  Thanks for your reply, but isn't there an easier way to add a typical roller restriction?
  
• disla

  October 30 edited October 30

  Hi,
  
  If you distribute the load over a certain surface below the plate you could use the rigid body as it is implemented (based on a surface and a REF node).
  Mecway have shortcuts for some elaborated BC but not all of them.
  
  
• disla

  October 30

  This is the fastest rolling set up I can imagine. Not what you first ask as nodes are not enforced to keep aligned but could be valid for small displacements.
  

  Fast rolling base .liml 100.7K
• Mag

  October 30

  Hi Disla,
  Yeah, it coul be valid for small displacements. Unfortunately it is not what I need. Thank you so much!
• disla

  October 30

  Give it a try to Straight. It should do the job.
  
  I have edit one of my previous posts:
  
  Straight allows the nodes on the line to stretch and change distances in between them while keeping them aligned.
• Victor

  October 30 edited October 30

  You can use Node-surface coupling for this with either the internal or CCX solver, and small or large displacements. Here's an example. Note that the line axis (Y) rotation constraint is required when the nodes are collinear and it isn't actually constraining rotation of the plate.
  
  But I might be misunderstanding because I think @disla's solution (Z displacement constraints) usually does this and should be fine for large displacements too, shouldn't it? Do you really want to make the line rigid so all its nodes together have only 2 degrees of freedom and it can't deform or rotate about the Z axis? That would physically be one big high-stiffness support fixing a strip on the surface, not a row of independent roller supports.
  

  Fast rolling base rigid body.liml 102.1K
• disla

  October 30 edited October 30

  OH, That's new ¿isn't it?. I mean Rigid body definition through a set of nodes instead of surface.
  I'been doing this manually for a long time .
  I think y rotation should be free to be a hinge.
  

  Fast rolling base rigid body Victor.liml 101.9K
• Victor

  October 30

  Yes, since version 25, in part because you pointed out the need. Sorry it slipped by.
  
  The Y-rotation constraint is for the reference node (ROT node), but structure itself is free to rotate about the line of nodes because there's no way for a rigid body connecting displacement DOFs to constraint that motion.
  
  I put in the Y rotation constraint on the advice of the CCX manual after it was failing without it. Your version also fails sometimes (Spooles). I think that extra constraint removes a redundant rigid body DOF caused by the nodes being collinear.
• disla

  October 30

  I put in the Y rotation constraint on the advice of the CCX manual after it was failing without it

  
  
  That's weird. I didn't notice that because I always use PARDISO MKL and it has been working fine for me. You are completely right. Adding rot y constrained makes it to work also with spools although it doesn't have any effect. Good to know for other users using different solvers.