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Contact options

*Contact options, Name=<interaction name>, [clearance=<normal contact distance>], [ Check Disp = <Fraction of contact length>], [ Check Dist = <Fraction of contact length>], [ Reduction]

This option defines additional and optional contact interaction definitions. It is not mandatory to use and does not have to be altered in almost all cases.

  • The clearance option defines an initial normal gap of the contact interaction, which enforces the contacts to remain open (or overlapped) with the defined normal distance. Positive values for c indicate an open contact, while negative values indicate overlapping.


  • The Check Disp option defines the fraction of the displacement magnitude of the contact nodes at which a update of the node-to-node connectivity is performed. The value defined is the fraction of the characteristic contact length (length of element edge) and is by default 0.05.

  • Check Dist defines the maximum contact point distance for which contact quantities are still computed based on the fraction of the characteristic contact length. This factor is by default \(2.5\). If the user encounters contacts that are not computed (identifiable e.g. by zero contact distance) even if they should have to be, an increase of Check Dist can be a possible solution. Likewise, if the user encounters that nodes have contact stress which should not, reducing the value of Check Dist (or changing the contact conditions) may help.

  • With the Reduction keyword interface properties are included in strength-reduction analyses for the determination of the Factor of Safety \(FoS\). If activated, the friction coefficient, dilatation angle and adhesion are obtained by

    \[ \tan(\delta) = \dfrac{\tan\delta_0}{FoS} ~~~;~~~ \tan(\psi) = \dfrac{\tan\psi_0}{FoS} ~~~;~~~ c = \dfrac{c_0}{FoS} ~~~ \text{for} FoS > 0 \]

    Therein, \(\delta_0\), \(\psi_0\) and \(c_0\) are the interface properties provided at the start of the analysis. This option is deactivated by default and (if activated) will only be considered during steps of type *Reduction (strength-reduction analyses).