Line data: Mid-line connections

Mid-line connections are those from child mid-line nodes (i.e. nodes other than end nodes) to other (parent) objects. The data required for each connection are: the arc length of the node, the position and orientation of the connection, and whether the connection is released during the simulation. Mid-line connections are broadly similar to end connections, with a few differences:

Notes: It is not possible to use mid-line connections when the line's length and end orientations are calculated from end positions.
It is not possible to use the spline and prescribed step 1 statics methods for a line which has mid-line connections.
A line with mid-line connections can only be a supported line or a splined line in a line contact relationship if the line includes torsion.

The mid-line connection data are given in a table, each row of which defines a node on the line and that node's connection data. The data are:

Arc length, relative to

The connection is made from the node whose reference arc length is closest to the specified arc length, measured relative to either end A or end B, as specified.

Warning: If a line uses line feeding or is partly inactive, then the actual arc length of the node where the connection is made may vary as this node approaches a line end at which feeding occurs.

Node arc length

The reference arc length of the node where the connection is made.


The parent object to which the mid-line node is connected.

Position, z relative to

The position of the centre of the node. The precise meaning of this item depends on the nature of the connection:


When a mid-line node is connected to an object, it is rigidly connected to that object and rotates with it. You define the orientation of this connection by giving the child node's azimuth, declination and gamma angles relative to the parent object axes. For fixed or anchored connections, this orientation is given relative to global axes.

The orientation angles are defined and interpreted in exactly the same way as the end connections orientation angles.

Release at start of stage

If desired, the node can be disconnected at the start of a given stage of the simulation. For no disconnection, set this item to '~'.