Stiffnesses for contact springs. The force in normal direction of the contact spring is determined from where is the normal displacement difference of the two nodes (that is, the displacement of the second node in normal direction minus the displacement of the first node in normal direction). The first tangential force of the contact spring is determined from where is the tangential displacement difference of the two nodes in the first tangential direction; the same is done for the second tangential force. The total tangential force cannot exceed with friction coefficient; then frictional slip occurs and the total tangential force is set to To model continuing stick between two bodies just put the friction coefficient very high.
In 1D the parameters and will not be used (but should be specified as dummies nevertheless).
The index specifies the element_group, see element_group.
See also group_contactspring_friction and group_contactspring_friction_automatic.