Use the Rigid Body Contact node () to model structural contact between rigid bodies. In the contacting bodies, the source must be always a rigid sphere (3D) or a rigid circle (2D). The destination can be of two types; either a rigid sphere (or circle) or of arbitrary shape.

If friction is to be included, add a Friction (Rigid Body Contact) subnode.

This section shows a sketch of the rigid body contact for different settings in the Destination section. The sketch highlights the source center, the source radius, the destination center, the destination radius, the distance between source center and destination contact point, and the gap.

Specify the Shape of the source. The currently available choices are Spherical in 3D, and Circular in 2D.

From the Source list, select a Rigid Domain node available in the Multibody Dynamics interface. The default value is None. Enter the radius of the Source rigid body using the Radius input.

Select the Center — Centroid of source, Centroid of selected entities, or User defined.

Specify the Shape — Spherical (3D), Circular (2D) or Arbitrary.

Choose Spherical to model structural contact between two rigid bodies of spherical shape in 3D. Similarly, by setting Shape to Circular in 2D, you can model the structural contact between two circular rigid bodies.

If the Shape is set to Spherical (3D) or Circular (2D), a Destination list is available. Select a Rigid Domain, different from the one selected as Source. The default value is None. Enter the radius of the Destination rigid body using the Radius input.

Select the Center — Centroid of destination, Centroid of selected entities, or User defined.

Select Use inside boundaries for contact if the location of the source is inside the destination sphere. In this case, the inner boundaries of the destination are used for the gap distance and contact force calculations.

If the Shape is set to Arbitrary, you can select a set of destination boundaries for the contact in the Boundary Selection, Destination section. These boundaries need not necessarily be part of any Rigid Domain nodes. The boundary selection can be specified for 3D and 2D models.

Under Formulation, you select the algorithm used for computing the contact. Select Penalty or Penalty, dynamic (default).

The Penalty, dynamic is intended for use in time-dependent studies to model dynamic contact.

Select the type of Penalty factor control — Automatic or User defined.

Select the type of Penalty factor control — Automatic; Viscous only or User defined. The settings are the same as for the standard penalty method, except for the Viscous only option. By selecting Viscous only, the stiffness terms of the penalty contact are omitted from the formulation.

Select the type of Viscous penalty factor control — Automatic or User defined. For Automatic, enter a value for the Characteristic time τn. This value can be used as a multiplier for the viscous penalty factor, but should as a rule-of-thumb be in the same order of magnitude as the duration of the contact event. When User defined is selected, enter the Viscous penalty factor pnv. The default value is (1e10[N/m^2])*mbd.diag)*1[ms], where mbd.diag is the diagonal of the bounding box of the geometry.

When Formulation is set to Penalty, dynamic, select Compute viscous contact dissipation to compute and store the energy dissipated by the viscous contact. This adds a global dependent variable with an ODE for energy integration purpose.

Physics tab with Multibody Dynamics selected: