User Defined
A general connection between the two rotors can be established using the User defined option. The degrees of freedom are split into three types: displacement, bending rotation, and axial rotation. Each type of degree of freedom can be rigidly or flexibly connected. In the rigid case, a constraint is applied across the degrees of freedom on both rotors. In the flexible case, a force (moment) proportional to the degree of freedom is applied. The following sections describe the corresponding constraints and forces (moments) for various types of connections.
Displacement Connection
For a rigid connection, the following constraints are applied on the interior boundary:
On the exterior boundary, the constraint is:
If the connection is flexible, the force acts on the relative translation of the two rotors on the interior boundary:
Note that the relative motion is offset by the misalignment value, if any. Thus, the misalignment acts like a predeformation in the spring.
On an exterior boundary, the force is given by
Axial Rotation Connection
On an interior boundary, the following constraints are applied for a rigid case:
On an exterior boundary, the constraint changes to
For a flexible connection on the interior boundary, the following torsional moment is applied on the relative axial rotation:
On an exterior boundary it is
Bending Rotation Connection
For a rigid connection, the following constraints are applied on an interior boundary:
On an exterior boundary, the constraints are changed to
In the case of a flexible connection, the following moments act on an interior boundary on the relative tilting motion of the two rotors:
On an exterior boundary, the moments are
.
Misalignment values can be specified in the Misalignment feature, available as a subnode for Rotor Coupling.