Mass and Moment of Inertia (Rigid Domain)
Use the Mass and Moment of Inertia subnode to add an effect of associated abstract rigid domain, which is physically not modeled and whose inertial properties are known. These inertial properties can be specified at an arbitrary point in space which is assumed to be the center of gravity of this extra mass. The moment of inertia tensor that you specify is interpreted in the selected coordinate system.
Center of Mass
Here you specify the location of the center of mass for the contribution given in this node. Select an option from the list: Center of rotation, Centroid of selected entities, or User defined.
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For Center of rotation, the location of the load is taken as the center of rotation as defined in the parent Rigid Domain node.
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For Centroid of selected entities select an Entity level — Boundary, Edge, or Point. The available choices depend on physics interface and geometrical dimension.The center of mass is located at the centroid of the selected entities, which do not need to be related to rigid domain itself. As a special case, you can select a single point, and thus position the mass at that point
Once chosen, a default Center of Mass: Boundary, Center of Mass: Edge, or Center of Mass: Point subnode is automatically added.
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For User defined, enter the Global coordinates of center of mass, Xm, in the table.
Select the Offset check box to add an optional offset vector to the definition of the location. Enter values for the offset vector Xoffset.
The center of mass used is the sum of the vector obtained from any of the input methods and the offset vector.
Mass and Moment of Inertia
Enter values or expressions for the Mass m. Then for the Moment of inertia the axis directions of the moment of inertia tensor are given by the selected coordinate system.
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For 3D components, select Isotropic (the default), Diagonal, or Symmetric and enter one or more components for the tensor I.
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For 2D components, enter a value or expression for Iz.
Location in User Interface
Context Menus
 Solid Mechanics>Rigid Domain>Mass and Moment of Inertia
 Shell>Rigid Domain>Mass and Moment of Inertia
Layered  Shell>Rigid Domain>Mass and Moment of Inertia
 Beam>Rigid Domain>Mass and Moment of Inertia
 Multibody Dynamics>Rigid Domain>Mass and Moment of Inertia
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Physics tab with Rigid Domain node selected in the model tree:
Attributes>Mass and Moment of Inertia