Creating Distributed Masses

Distributed Masses are used to model purely inertial (non-structural) system characteristics such as additional equipment. They represent scalar point mass fields equivalent to a total mass concentrated at a given point, distributed on a virtual part or on a geometric selection.

The user specifies the total mass. This quantity remains constant independently of the geometry selection. The point where the total mass is concentrated is automatically defined as follows:

	For extended geometries, this point is the centroid of the geometry.
	For virtual parts, this point is the handler of the virtual part.

The given concentrated-mass system is processed by the program as follows:

	In the case of extended geometries, it is transformed into an equivalent lumped masses system distributed over the selected support.
	In the case of virtual parts connected to deformable bodies, it is transmitted as a lumped masses system collectively to the entire connected geometry.

Units are mass units (typically kg in SI).

Mass sets can be included in static cases: in this case, they are used for loadings based inertia effects.

Distributed Mass can be applied to the following types of Supports:

Mechanical Feature	Geometrical Feature				Analysis Feature
Mechanical Feature	Point or Vertex	Curve or Edge	Surface or Face	Volume or Part	Analysis Feature
					Virtual part

This task shows you how to create a Distributed Mass applied to a virtual part or to a geometry selection.

You can use the sample16.CATAnalysis document from the samples directory for this task: a Finite Element Model containing a Static or Frequency Analysis Case.

Before You Begin:
Go to View -> Render Style -> Customize View and make sure the Shading, Outlines and Materials options are active in the Custom View Modes dialog box.

1. Click the Distributed Mass icon

.
The Distributed Mass dialog box is displayed.

2. You can change the identifier of the Distributed Mass by editing the Name field.

3. Enter the value of the total Mass to define the mass magnitude.

4. Select the support (a vertex, an edge, a face or a virtual part) on which the concentrated mass is applied at the pre-defined point. Any selectable geometry is highlighted when you pass the cursor over it.

You can select several supports in sequence, to apply the Distributed Mass to all supports simultaneously.
Symbols representing the total mass equivalent to the Distributed Mass are displayed at the application point of the support to visualize the input lumped mass system.

5. Click OK to create the Distributed Mass.
A Distributed Mass.1 object appears in the features tree under the active Masses objects set.

	You can either select the support and then set the Distributed Mass specifications, or set the Distributed Mass specifications and then select the support.
	If you select several geometric supports, you can create as many Distributed Masses as desired with the same dialog box. A series of Distributed Masses can therefore be created quickly. The point where the total mass is initially concentrated is automatically assumed to be the centroid of the system of individual supports centroids.
	Non-Structural Masses are not required for either Stress Analysis or Modal computations.
	If several Analysis Cases have been defined in the Finite Element Model, you must activate a Masses objects set in the features tree before creating a Distributed Mass object (only available if you have ELFINI Structural Analysis product installed).
	Distributed Mass objects can be edited by a double click on the corresponding object or icon in the features tree.

Make sure the computation is finished before starting any of the following operations.

Products Available in Analysis Workbench

The ELFINI Structural Analysis product offers the following additional features with a right mouse click (key 3) on a Distributed Mass object:

Distributed mass visualization on mesh: the translation of your Distributed Mass object specifications into solver specifications can be visualized symbolically at the impacted mesh entities, provided the mesh has been previously generated via a Compute action.

The ELFINI Structural Analysis product offers the following additional features with a right mouse click (key 3) on a Masses objects set:

Generate Image:
Generates an image of the Local Update action (which translates all user-defined Masses specs into explicit solver commands on mesh entities), by generating symbols for the elementary masses imposed by the Masses objects set. The image can be edited to include part or all of the options available.
Right-click (key 3) on a Masses objects set and select the Generate Image option. The Image Choice dialog box is displayed. You can select images by clicking them in the list.

The resulting images sequence is obtained by superposition.

Report:
The partial status and results of intermediate pre-processor computations are reported in HTML format. It represents a subset of the global Report capability and generates a partial report of the Masses objects set Computation.

Click the Basic Analysis Report icon (on the condition you previously computed a solution using the Compute icon ).

Click OK in the Reporting Options dialog box that appears (if you have more than one analysis case, ensure that the relevant analysis case is highlighted in the dialog box).

The .html partial report file is displayed.