Rigid Body Checks dialog box (Nastran/Multiphysics)

General options

Name	Description
Name	Defines the name of the modeling object.
Label	Specifies a unique numerical identifier for the modeling object.

Grounding Check tab options

Name	Description
Enable GROUNDCHECK Request	Controls whether the software performs a grounding check analysis on the model’s stiffness matrix to expose unintentional constraints by moving the model rigidly. This option corresponds to the Nastran GROUNDCHECK case control command.
Output
Output Medium	Controls where the software writes the output from the GROUNCHECK command.Select PRINT to write the output to the print file.Select PRINT, PUNCH to write the output to the print and punch files.Select NOPRINT, PUNCH to write the output to the punch file.Select NOPRINT if you do not want to write the output to the print file.
Degree of Freedom Sets
Degree of Freedom Sets	Controls at which stage of the stiffness reduction that Nastran performs the check. This option corresponds to the SET describer for the GROUNDCHECK case control command.Select ALL to perform the check at all stages of the stiffness reduction.Select G to perform the check after multipoint constraints and rigid elements are applied.Select N+AUTOSPC to use the stiffness matrix for the n-set with the rows corresponding to the degrees-of-freedom constrained by the PARAM,AUTOSPC operation zeroed out.Select F to perform the check after single point constraints, multipoint constraints, and rigid elements are applied.Select A to perform the check after static condensation of the stiffness matrix.
Reference Node
Select Reference Node	Lets you select the reference node (grid point) that the software uses to calculate the rigid body motion.
Maximum Strain Energy Threshold
Threshold	Select this option if you want to specify the maximum strain energy value that you want to allow to pass the check. Then, specify the Threshold value.
Grounding Forces
Data Recovery	Controls whether you want the software to recover the data of grounding forces.
Threshold	Select Threshold if you want to specify the threshold value for grounding forces.
Percentage of Largest Grounding Force	Lets you specify a threshold value for the data recovery of grounding forces. The software prints the grounding forces larger than this specified percentage of the largest grounding force. Enter a value that is greater than 0 and less than 1.

Mass Reduction Check tab options

Name	Description
Enable WEIGHTCHECK Request	Controls whether, at each stage of the mass matrix reduction, the software computes the rigid body mass and compares it with the rigid body mass of the g-set. This option corresponds to the Nastran WEIGHTCHECK case control command.
Output
Output Medium	Controls where the software writes the output from the WEIGHTCHECK command.Select PRINT to write the output to the print file.Select NOPRINT if you do not want to write the output to the print file.
Output Center of Gravity and Mass Moments of Inertia	Controls where the software calculates the model’s center of gravity and mass moments of inertia.
Output Units	Controls where the software calculates the rigid body mass in units of weight or mass.
Degree of Freedom Sets
Degree of Freedom Sets	Controls at which stage of the mass matrix reduction that Nastran performs the check. This option corresponds to the SET describer for the WEIGHTCHECK case control command.Select ALL to perform the check at all stages of the stiffness reduction.Select G to perform the check after multipoint constraints and rigid elements are applied.Select N+AUTOSPC to use the mass matrix for the n-set with the rows corresponding to the degrees-of-freedom constrained by the PARAM,AUTOSPC operation zeroed out.Select F to perform the check after single point constraints, multipoint constraints, and rigid elements are applied.Select A to perform the check after static condensation of the stiffness matrix.Select V to perform the check
Reference Node
Select Reference Node	Lets you select the reference node (grid point) that the software uses to calculate the rigid body mass.

Learn more

Checking for unintentional grounding and mass reduction

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Rigid Body Checks dialog box (Nastran/Multiphysics), Simcenter 3D 2021.1 Series

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