Analyzing Degrees of Freedom 

This task explains how to see if you need to set additional constraints to the components that make the assembly.
The degrees of freedom analysis is performed from assembly constraints only. This is mean that constraints from design in context or assembly pattern are not taken into account.

The analysis is performed from the active component and its child components set, but you must know that:

  • Selecting of any sub-component of a child component returns the analysis of this child component relative to its active parent component only. If you want to analyze the sub-component relative to a child component, activate the child component before.
  • Flexible child components (and their flexible sub-components) of the active component are not taken into account for the analysis. In this case, the analysis is performed from the first rigid sub-component found in the selection, under the active component.

Translations can be performed in a plane is represented by two vectors. These vectors define the translation plane but depending on the geometry, they can constitute an orthonormal system or not. In other words, a planar translation which normal to the plane has the coordinates (x=0, y=1, z=0) can sometimes be represented by:

  • These two vectors:
    • vector 1: x=0, 707107, y=0, z=0,707107
    • vector 2: x=-0, 707107, y=0, z=-0, 707107
  • or by these ones:
    • vector 1: x=1, y=0, z=0
    • vector 2: x=-0, y=0, z=1
Open the Assembly_07.CATProduct CATProduct document.

  1. Click the Update icon to update the assembly:

 

  1. Right-click CRIC_SCREW (CRIC_SCREW.1) and select the Analyze > Degrees of Freedom command command from the contextual menu.
 
 

The Degrees of Freedom Analysis dialog box is displayed.
 
 

The dialog box displays all rotations and translations that remain possible for the selected component. In our scenario, you can rotate CRIC_SCREW (CRIC_SCREW.1) in two ways or translate it in one way.

 

If you look at the geometry, you can notice that these rotations and translations are represented in yellow.
 

  1. Click the Rotation_2 button.
 

The graphic element representing this possible rotation is now highlighted in the geometry for easy identification.
 
 

As detailed in the dialog box, you can perform a rotation around the vector which coordinates are x=1, y=0 and z=0 and using the point with coordinates x=0, y=-23.4839 and z=-151.254 as the rotation center.
 

  1. Click the Translation_2 button.
 

The graphic element representing this possible rotation is now highlighted too.
 
 

As detailed in the dialog box, you can perform a translation along the vector which coordinates are x=0, y=0.984808 and z=-0.173648.
 

  1. Click Close to exit the command.