Fixed and free boundary degrees of freedom (Nastran, ANSYS, and Abaqus)

You can use the Fixed Boundary Degrees of Freedom or Free Boundary Degrees of Freedom constraints with the Simcenter Nastran superelement and Simcenter Nastran, ANSYS, and Abaqus flexible body solutions to define degrees of freedom for the boundary where a component is connected to other components in the structure.

These constraints are available for the following solutions:

Simcenter Nastran

• SOL 101 – Superelement (Fixed Boundary Degrees of Freedom only)

• SOL 103 – Superelement

• SOL 103 – Flexible Body

ANSYS

• Modal Flexible Body

Abaqus

• Modal Flexible Body (Fixed Boundary Degrees of Freedom only)

• Substructure Generation step

Use a Fixed Boundary Degrees of Freedom constraint to define the connection degrees of freedom for the boundary. For example, in a flexible body solution, this is where the component is connected to the mechanism through a joint or bushing.

Use a Free Boundary Degrees of Freedom constraint to define the load degrees of freedom for the boundary. For example, in a flexible body solution, this is where a force, torque, spring, or damper is applied to the component.

For more information, see Superelement analysis and Flexible body analysis.

For information about fixed and free boundary degrees of freedom in the Simcenter Samcef environment, see Fixed and free boundary degrees of freedom (Simcenter Samcef).

Where do I find it?

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter Nastran, ANSYS, or Abaqus as the specified solver
Command Finder	Fixed Boundary Degrees of Freedom Free Boundary Degrees of Freedom
Simulation Navigator	Right-click Constraint Container→New Constraint→Fixed Boundary Degrees of Freedom or Free Boundary Degrees of Freedom

Learn more

Contact interference (Abaqus)

Constrained keywords for rigid body creation (LS-DYNA)

Enforced acceleration constraint (ANSYS)

Initial forces on beam element axes (LS-DYNA)

Initial stress (LS-DYNA)

Initial velocity (LS-DYNA)

Rigid wall definition (LS-DYNA)

Single point constraints for boundary nodes (LS-DYNA)

Enforced velocity constraint (ANSYS)

Superelement analysis

Flexible body analysis

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Fixed and free boundary degrees of freedom (Nastran, ANSYS, and Abaqus), Simcenter 3D 2021.1 Series

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