# Contact Surfaces

Contact surface entities define and store contact definitions typically used in contact analysis.

Contact surfaces are defined using elements (1D/2D/3D) and their respective facecodes. A contact surface is displayed as an arrow on the selected element faces in the modeling window. The direction of the arrow is along the element normal that defines the contact surface.

## EXODUS Cards

Card Description
SideSets Provides a second means of applying loads and boundary conditions to the model.

## LS-DYNA Cards

Card Description
*SET_SEGMENT Definition segments on element faces.

## Nastran Cards

Card Description
ELIST Defines a list of CQUAD4 and CTRIA3 structural elements for virtual fluid mass.

## OptiStruct Cards

Main Secondary contact is represented using contact surfaces.
Card Description
ELIST Specifies damp shell elements for a fluid volume. ELIST entries are referenced by the MFLUID entry.
SURF Defines a face of a 2D or 3D element as part of a surface.

## Permas Cards

Card Description
$SURFACE Surface definition. Note: The name of the contact surface is getting exported to the SFSET parameter. On import, the contact surface will be named after the SFSET parameter. Known limitations: • The reader does not combine two individual$SURFACE cards into a surface set if the carry the same name.
• Several surfaces can be combined by an $SFSET card instead.$SURFACE_GEO Surface defined by interpolation of nodes.