Distributing Masses and Inertias

You can distribute masses and inertias on a selection of geometries or on a virtual part. Distributing masses and inertias lets you take into account a spatial distribution of mass on a selection of geometries or on a virtual part.

To simulate a weight on a virtual part, you must couple a mass and an acceleration.

Before you begin: A structural analysis simulation containing a mass set must be open.
Related Topics
Working with Excitations
Authorized Supports
Modifying the Axis System
Reviewing Specifications
Creating Accelerations

  1. In the Masses toolbar, click Distributed Mass and Inertia .

    The Distributed Mass and Inertia dialog box appears.

  2. Optional: In the Name box, modify the name of the mass.

  3. Select the support (a vertex, an edge, a face, a body or a virtual part) on which you want to distribute masses and inertias. Any selectable geometry is highlighted when you pass the cursor over it. Multi selection is available for geometries and groups. Multi selection is not available for virtual parts.

  4. Optional: By default, the vector components are defined relative to the fixed global axis system (fixed global rectangular coordinate system).

    To choose a different axis system, select User in the Type list, and select a user axis system in the specification tree. The name of the user axis system is displayed automatically in the Current axis box, and the components of the resultant force are defined relative to the specified rectangular axis system.

  5. In the Mass box, enter a value to define the mass magnitude.

  6. In the I11, I22, I33, I12, I13, and I23 boxes, modify the components of the mass inertia matrix.

  7. Optional: Select a handler point.

    • For a geometry or group support, you can select a point. If you do not select any handler point, the center of gravity of nodes is selected by default as handler of distribution.
    • For a virtual part support, you cannot select a handler point.

  8. Click OK.

    A Distributed Mass and Inertia.1 object appears in the specification tree under the active mass set.


    • When you select a geometry as support of a distributed mass and inertia, the only available image is Mass inertia (3x3 mass tensor). Point mass image (punctual tensor) and Mass moment of inertia image (3x3 inertia tensor) are not available.
    • When you select a virtual part as support of a distributed mass and inertia, the only available images are Point mass image (punctual tensor) and Mass moment of inertia image (3x3 inertia tensor). Mass inertia (3x3 mass tensor) is not available in this case.