Connector Elasticity to define rotational stiffness
- Philip Dai

- Apr 18, 2024
- 1 min read
**
*Node
1, 0., 19121.25, 0.
*Element, type=CONN3D2
1, 1, Beam_CS-1.1
*Connector Section, elset=Wire-1-Set-1, behavior=ConnSect-2_RotStiffness
Hinge,
"Datum csys-2",
*Nset, nset=Bottom, instance=Beam_CS-1
193,
*Nset, nset=RP
1,
*Nset, nset=Wire-1-Set-1
1,
*Elset, elset=Wire-1-Set-1
1,
*Orientation, name="Datum csys-2"
0., 0., 1., 0., 1., 0.
1, 0.
**************
*Connector Behavior, name=ConnSect-2_RotStiffness
*Connector Elasticity, component=4
6e+10,
The stiffness is defined as below:
6.00E+10 | Nmm/radians |
1.05E+09 | Nmm/deg |
1047.198 | kNm/deg |
Orientation systems

Data lines to define an orientation using DEFINITION=COORDINATES:
First line:
X-coordinate of point a.
Y-coordinate of point a.
Z-coordinate of point a.
X-coordinate of point b.
Y-coordinate of point b.
Z-coordinate of point b.
The following items, the coordinates of point c (the origin), are optional and relevant only for SYSTEM=RECTANGULAR and SYSTEM=Z RECTANGULAR. The default location of the origin, c, is the global origin.
X-coordinate of point c.
Y-coordinate of point c.
Z-coordinate of point c.
Second line (mandatory for shells, membranes, gaskets, composite solid sections, and contact pairs):
Local direction about which the additional rotation or rotations are given. The default is the local 1-direction. For shell, membrane, and cohesive elements this direction should have a nonzero component in the direction of the normal to the surface.
Additional rotation (in degrees) applied to both directions orthogonal to the specified local direction. The default is zero degrees.






If the connector has no internal stiffness (because you didn’t define a *Connector Behavior), then applying an external force to its axial DOF will generally cause the two nodes to slide relative to each other along the connector axis. Here’s why:
The axial connection type only introduces a degree of freedom; it does not restrain it unless you add stiffness or constraints.
Without stiffness, the connector behaves like a kinematic link—it can measure relative displacement (CU1, CNL) but does not resist it.
So, if you apply a Connector Load (e.g., *Connector Load, component=1) or a force through other means, the nodes will move apart unless:
You fix CU1 with a boundary condition, or
The nodes are restrained by other elements or constraints in the model.