Extending the legs of spider elements in bolt connections

When you generate bolt connection elements from the Connection Manager dialog box, you can select the 2 Rings Spider check box in the Bolt Element dialog box to extend the legs of spider-type elements, such as Nastran RBE2 elements, to connect to the second ring of nodes around the bolt, even if the diameter of the bolt's head does not include those nodes.

Top view of a bolt element created with the 2 Rings Spider option selected

In many cases, you define the size of the bolt's Head Diameter with respect to the diameter of bolt to be used in the actual physical model. However, the element size for the mesh on the connected components may be based on other criteria. Consequently, situations can occur where the imprint of a bolt's head does not include enough elements around the bolt hole. In those cases, the legs of spider-type elements that connect to the nodes around the bolt hole are too short to adequately represent the connection, which can negatively impact the results. Extending a spider element's legs to connect to the second ring of nodes around a bolt hole improves the connectivity of the bolt and leads to more accurate results for the connection.

Where do I find it?

Application	Pre/Post
Prerequisite	A FEM or assembly FEM file as the work part and displayed part
Command Finder	Universal Bolt Connection Connection Elements Automatic Connection Elements

Bolt universal connection customer defaults

Menu	File→Utilities→Customer Defaults
Location in dialog box	Simulation→Pre/Post→Universal Connections→ Bolt tab

How do I

Simulate a bolt preload in ANSYS using universal bolt connections

Create large quantities of bolts in one connection

Learn more

Bolt universal connections

Override the length of bolt shanks

Bolt universal connections in the Nastran environment

Bolt universal connections in the LS-DYNA environment

Meshing LS-DYNA bolt connections with rigid body elements

Meshing LS-DYNA bolt connections rigid body and beam elements

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Extending the legs of spider elements in bolt connections, Simcenter 3D 2021.1 Series

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