Constrained keywords for rigid body creation (LS-DYNA)

In the LS-DYNA environment, you can use the Constrained Keywords command to define connections and motions for a rigid body. Use the options in the Constrained Keywords dialog box to specify how to constrain selected nodes to define the rigid body.

Option	Description	LS-DYNA Keyword
CONSTRAINED_NODE_SET	Defines sets of nodes that are constrained in their translational degrees of freedom.The nodes that you include in a CONSTRAINED_NODE_SET definition should not be subjected to any other constraints.Since the CONSTRAINED_NODE_SET option does not allow any rotation, you should not use the CONSTRAINED_NODE_SET option to model rigid body behavior that involves rotations.	*CONSTRAINED_NODE_SET
CONSTRAINED_NODAL_RIGID_BODY	Defines a nodal rigid body. The software uses the equations of rigid body dynamics to update the motion of the nodes. You can also define rotations of the nodal sets. The software calculates mass properties from the nodal masses and coordinates. Note: You can also use the 1D Connection command in the FEM file to use the *CONSTRAINED_NODAL_RIGID_BODY keyword to create a rigid connection between components. For more information, see Defining constrained joint connections for LS-DYNA models.	*CONSTRAINED_NODAL_RIGID_BODY
CONSTRAINED_EXTRA_NODES	Defines additional nodes for the rigid body. You can define extra nodes anywhere in the model, even outside of the rigid body. The software assumes that these nodes are part of the rigid body. You can define extra nodes, for example, to define the location where joints will connect rigid bodies or to specify a lumped mass at a specific location.	*CONSTRAINED_EXTRA_NODES

Where do I find it?

Application	Pre/Post
Prerequisite	An active Simulation file with LS-DYNA as the specified solver
Command Finder	Constrained Keywords
Simulation Navigator	In the appropriate solution, right-click Constraint Container→New Constraint→Constrained Keywords

Learn more

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Constrained keywords for rigid body creation (LS-DYNA), Simcenter 3D 2021.1 Series

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