I used the command CERIG to create some rigid links, but I am getting the following error message:
Label ROTZ is not an active DOF. The CERI command is ignored.
What does this mean, and what can I do to fix it?
The CERIG command is trying to form a rigid region controlled from one node, but if this one node has no rotational degree of freedom, then the rigid region could not rotate. The simplest way to resolve this is to add a massless mass element which has a ROTZ in it at the master node. Please see the following example:
! I'll arbitrarily choose a region to be rigid
! but since I don't have rotational DOF, I'll add a point mass
! then, I'll use CERIG to make it rigid
! you may want to delete the unneeded nodes elements
! before creating the rigid region, but they are left
! here to demonstrate that they carry no load