Wire Spring Constraint
Provides controls for setting up basic spring constraints for wire objects.
This tool constrains points on the wire object to a “goal” location derived from another simulation object or from a position in world space. You need to create a 
Wire Object before invoking this tool. You can use this tool, for example, to simulate a bungee cord.
Using Wire Spring Constraint
Click the
Wire Spring Constraint button on the Wires tab.Select the
Wire Object or points on the wire object to constrain and press Enter to confirm your selection.Note
If you select the whole object, the constraint will be placed at the root of the object.
For specific parameter help see the 
SBD Spring Constraint node help.