Multibodies collect and organize ellipsoids, multibody planes, and multibody joints and are typically used in multi-body analysis.  Multibodies are created, edited, and deleted from the Model browser and are shown under the Multibody folder.

Ellipsoids, multibody planes, and multibody joints can be organized into a multibody using the Organize panel.  Every ellipsoid, multibody plane, and multibody joint must be organized into one, and only one, multibody and therefore are mutually exclusive to a multibody.  Newly created ellipsoids, multibody planes, and multibody joints are automatically organized into the current multibody.

The current multibody is shown bold in the Model browser.  The current multibody can be set using the Model browser context menu on a selected multibody within the Multibody folder.  Multibodies can also be card edited using the Model browser context menu on selected multibodies.

Multibodies have a display state, on or off, which control the display of all ellipsoids, multibody planes, and multibody joints organized within the multibody in the graphics area.  The display state of a multibody can be controlled using the icons next to the multibody in the Model browser.

Multibodies also have an active and export state.  The active state of a multibody controls the display state of the multibody and the listing of the multibody in the Model browser and any of its views.  If a multibody is active, then its display state is available to be turned on or off and it is listed in the Model browser and any of its views.  If a multibody is inactive, then its display state is turned off permanently and it is not listed in the Model browser or any of its views.  If a find operation "finds" an inactive multibody, that multibody will automatically be set to active.

The export state of a multibody controls whether or not that multibody and all ellipsoids, multibody planes, and multibody joints organized within the multibody are exported when the custom export option is utilized.  The all export option is not affected by the export state of a multibody.  The active and export states of multibodies can be controlled using the Entity State browser.

Operations performed on a multibody collector affect ellipsoids, multibody planes, and multibody joints within the multibody collector.  For example, if you delete a multibody collector, the ellipsoids, multibody planes, and multibody jonts within the multibody collector are also deleted.

The data names associated with multibodies can be found in the data names section of the HyperMesh Reference Guide.

 

Creating a Multibody Collector

The create subpanel is used for creating multibody collectors. Create provides four data blocks for defining: the collector's name, card image type, center of gravity, and the body’s local coordinate system.  Moments of inertia and other rigid body properties are defined in the multibody collector’s card image, which is access through the Card panel after the multibody collector has been created.

creation method: assigns the multibody type specified in the card image= field.  The types of multibody collectors available are dependent on the loaded solver interface specified as a template file. The most common type of multibody collector is a "rigid body".  Setting creation method: to no card image specifies that a multibody collector type is  not assigned at the time of creation, but one can be assigned later in the card image subpanel. Setting creation method: to same as assigns a copy of the card image of another multibody collector to the created collector. Using or not using a card image has no bearing on how multibody collectors behave and only effect data being exported.

center of gravity: provides an N1 node/geometry selection box to define the x, y, and z, location of the center of gravity.  The N1 box contains the same functionality as the N1 selection buttons found elsewhere in the program.  To define a center of gravity location, select a node on in the model window.  If only surfaces or lines are available for selection, click and hold the left mouse button in the model window until the cursor becomes a square, drag the cursor over geometry to select it, release the mouse button, and click anywhere on the geometry to define a location.  For an alternative method to define the center of gravity, click edit under the N1 selection box to bring up x=, y=, and z= entry fields.

body local system: defines the body local coordinate system of the created body by assigning a local coordinate system entity to the multibody collector. There are three ways to define the body’s orientation:

 

Updating a Multibody Collector

The update subpanel is provided to modify the body’s local coordinate system and center of gravity.  The same fields and options available in the create subpanel are also available in the update subpanel.

 

Solver Card Support for Multibody Collectors

---

 

 

See Also:

Model Browser

Organize panel

Entity State Browser

Browsers

HyperMesh Entities & Solver Interfaces

Include Files