Underconstrained Bodies PropertyManager

The Underconstrained Bodies tool detects the bodies in a part or assembly that are not sufficiently constrained during simulation and can exhibit rigid body modes.

The Underconstrained Bodies tool is available for static studies.

To open the Underconstrained Bodies PropertyManager, do one of the following:

  • From a static study tree, right-click Connections and click Underconstrained Bodies .
  • From the CommandManager, select Diagnostic Tools, and click Underconstrained Bodies .
Bodies that are not adequately supported by fixtures, connectors, bonded conditions, or contact interactions can translate or rotate freely. A body that is not constrained has six rigid body modes: three translational and three rotational.

The underconstrained bodies algorithm, in addition to fixtures and bonded conditions, takes into account the contact interactions that you define in a static study when analyzing rigid body modes.

  Calculate Detects the bodies in a part or assembly that exhibit translational or rotational rigid body modes.
  Results

Lists the bodies or group of bodies that exhibit rigid body modes.

Select one of the listed degrees of freedom (for example, Translation 1 or Rotation 1) to view an animated translation or rotation of the underconstrained bodies. A green arrow in the graphics area points to the direction of free movement (translation or rotation).

If no rigid bodies are detected, the solver issues a message that the model is fully constrained.

You can also expand and collapse the groups or bodies and modes in the results tree for better readability.
Copy to Clipboard

Copies the current results of underconstrained bodies to the clipboard. You can paste the copied data in a Microsoft Word or Excel document.

Stabilize any underconstrained bodies with the appropriate translational or rotational restraints before you proceed with the analysis. See also: Use Soft Spring to Stabilize Model and Preventing Rigid Body Motion.