﻿ To check and correct a rigid body
HyperCrash

# To check and correct a rigid body

From the Menu Bar, select Mesh Editing > Rigid Body > Check.

In the rigid body list, the green rigid bodies have a correct definition, the orange ones have to be checked, and the red ones have a bad definition. HyperCrash can automatically or semi-automatically correct the rigid bodies with errors or warnings.

A rigid body has a bad definition or must be checked if:

 • The main node is main node of several rigid bodies. Check the column, . If there is a "y" in this column, the rigid body is bad.
 • The main node is on an element. Check the column, . If there is a "y" in this column the rigid body is bad.
 • One or more secondary nodes belong to another rigid body. Check the column, . If the number in this column is greater than 0, the rigid body is bad.
 • The rigid body main node is also a secondary node of another rigid body. Check the column, . If there is a "y" in this column, the rigid body has to be checked.
 • The rigid body has one or zero secondary nodes. Check the column, . If the number in this column is less than or equal to 1 (1 or 0), the rigid body is bad.
 • In the same rigid body, if the main node is also selected as secondary. Check the column, M=S. If there is a "y" in this column, the rigid body is bad.
 • If a rigid body is small (small number of secondary nodes and/or small size) and if the spherical inertia option is not activated in the rigid body definition. Check the column, . If there is a "y" in this column, the rigid body has to be checked.

## Correction

### Main nodes in several rigid bodies

 1 Select a rigid body that has the main node in several other rigid bodies ("y" in the column, ).
 2 Click to display the rigid body in the graphic window.
 3 Click the right mouse button and, in the pop-up menu, select See Common Main of Rbodies to display the rigid bodies with common main nodes.
 4 No automatic corrections are available in this version.

### Main node on an element

 1 Select a rigid body that has the main node on an element ("y" in the column, ).
 2 Click to display the rigid body in the graphic window.
 3 Click the right mouse button and, in the pop-up menu, select See Rbody Main on element(s) to display the element connected to the main node.
 4 Click Save to automatically correct the rigid body.

It becomes green.

The rigid body main node and the element node are disconnected. The rigid body main node is moved to the secondary node center of gravity. The element node is included in the rigid body as secondary.

### Secondary nodes in other rigid bodies

 1 Select a rigid body that has a secondary node in other rigid bodies. (Number greater than 0 in the column, ).
 2 Click to display the rigid body in the graphic window.
 3 Click the right mouse button and, in the pop-up menu, select See secondary nodes in other Rbodies to display in blue the secondary nodes included in other rigid bodies.
 4 Deselect those nodes using the following buttons: , , , , or .
 5 Click Save to save the corrected rigid body.

It becomes green if all the slave nodes in other rigid bodies are removed.

### The rigid body main node is also secondary node of another rigid body

 1 Select a rigid body with a main node which is also a secondary node of another rigid body ("y" in the column, ).
 2 Click to display the rigid body in the graphic window.
 3 Click the right mouse button and, in the pop-up menu, select See Cascades of Rbodies to display the rigid bodies connecting the main node.
 4 Select the rigid body where the secondary node has to be deleted and click to display it in the graphic window.
 5 Deselect the node using the following buttons: , , , , or .
 6 Click Save to save the corrected rigid body.

### Rigid body with one or zero secondary nodes

 1 Select a rigid body that has one or zero secondary nodes. ("1" or "0" in the column, ).
 2 Click to delete it.

or

Click to display the rigid body in the graphic window.

 3 Add nodes to the rigid body (see Node and Part Selection) and click Save to save it.

It becomes green.

### In the same rigid body, the main node is also secondary.

 1 Select a rigid body having its main node defined also as secondary ("y" in the column, M=S).
 2 Click to display the rigid body in the graphic window.
 3 Click the right mouse button and, in the pop-up menu, select See Rbody Main is also secondary to display the rigid body main node in blue.
 4 Click Save to automatically correct the rigid body.

It becomes green.

The main node is removed from the secondary node list.

### Small rigid body without spherical inertia option.

 1 Select a rigid body that has a small size and no spherical inertia option. ("y" in the column ).
 2 Click to display the rigid body in the graphic window.
 3 Click Save to automatically correct the rigid body.

It becomes green.

The spherical inertia option is set in the rigid body definition.

### Semi-automatic correction

 1 Click to execute the previously defined steps semi-automatically.
 2 The first bad rigid body is automatically selected and displayed.
 3 The error or warning message is displayed.
 4 This loop continues until all rigid bodies are corrected.