Modeling the bolt's shank with a spring element

You can also model the bolt's shank as a zero-length spring element instead of a beam element. You may want to model the bolt with a spring element if you want to directly define the stiffness at the bolted joint and make force recovery simpler. When you solve your model, you can extract the forces or moments at the location of the spring. However, if you need to apply a pre-load to the bolt, you must use a beam element to model the bolt's shank.

In the Bolt Connection dialog box, select the Use Spring element to connect Head to Nut or the Use Spring element to connect Head to Tap option to model the bolt's shank using a zero-length spring element instead of a beam element.

Note:

If you select the Create Spider at Junction Plane option, you cannot use a spring element to model the bolt's shank.

If you use a spring element to model the bolt's shank, the software creates two coincident nodes in the middle of the bodies on which the head and nut or the head and tap are defined. The software connects the two nodes with a zero-length spring element. The two nodes are the core nodes for two spider-type connection elements.

• For the spider connection for the head of a bolt, the legs connect to all the nodes inside the head diameter on the specified head contact surface.

• For the spider connection for the nut of a bolt, the legs connect to all the nodes inside the nut diameter on the specified nut contact surface.

• For the spider connection for a tapped surface, the legs connect to all the nodes along the length of the tapped hole that lie within the specified Effective Thread Length.

The following graphic shows an example of bolt between a head and a nut that is modeled with a spring element.

• (A) shows the location of the two coincident nodes that are connected by a zero-length spring element. The distance between the nodes shown here has been exaggerated here for illustration purposes only.

• (B) shows the connections between the leg nodes of the bolt-side spider element and the nodes inside the head diameter.

• (C) shows the connections between the leg nodes of the nut-side spider element and the nodes inside the nut diameter.

Learn more

Modeling bolted connections

Understanding spider elements in bolted connections

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Modeling the bolt's shank with a spring element, Simcenter 3D 2021.1 Series

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