group_contactspring_stiffness index $k_N$ $k_T$

Stiffnesses for contact springs. The force $F_N$ in normal direction of the contact spring is determined from $F_N = k_N ~ u_N$ where $u_N$ 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 $F_{T1}$ of the contact spring is determined from $F_{T1} = k_T ~ u_{T1}$ where $u_{T1}$ 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 $\sqrt{ F_{T1} + F_{T2} }$ cannot exceed $f ~ F_N$ with $f$ friction coefficient; then frictional slip occurs and the total tangential force is set to $f ~ F_N$ To model continuing stick between two bodies just put the friction coefficient $f$ very high.

In 1D the parameters $k_T$ and $f$ 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.