Pre-loaded bolts modeled with beam elements (Nastran)

In the Bolt Pre-Load dialog box, you can use the Force on 1D elements option to define a pre-load on a bolt that is modeled with CBAR or CBEAM type beam elements.

Understanding bolt pre-load analysis process for 1D elements

With the Force on 1D elements option, when you solve your model, Simcenter Nastran first reduces the stiffness of the beam elements that represent the bolts by the value of the parameter BOLTFACT to make their stiffness insignificant.

Note:

In Pre/Post, you can modify the value of the BOLTFACT parameter through the Solution Parameters modeling object. From the Modeling Object Manager dialog box, select Solution Parameters from the Type list. In the Solution Parameters dialog box, expand the A-B group and then scroll down to the BOLTFACT parameter.

The software applies the Force that you specified in the Bolt Pre-Load dialog box to the ends of the bolts in the axial direction. The software then performs a linear statics analysis to obtain the relative displacements (U2 and U1) for each pair of nodes. The software then calculates the bolt strains as:

-(U2–U1)/L – P/AE

Where:

• U2 and U1 are the deflections at the ends of the bolt.

• L is the original length of the bolt.

• P is the defined bolt pre-load.

• A is the area of the bolt.

• E is the Modulus of Elasticity.

Selecting the elements that define the bolt

As a best practice, when you select the 1D elements to which to apply the bolt pre-load, you should select all the beam elements that define the shank of the bolt. In SOL 101, the software applies the pre-load to the first element you select and ignores any additional elements you select. However, SOL 601,106 and SOL 601,129 require that you select all elements along the shank of the bolt to define the pre-load. Always selecting all beam elements that define the shank of the bolt allows you to create a single bolt pre-load and then use it between the different solution sequences.

Note:

SOL 401 and SOL 402 do not support bolts modeled with beam elements.

How do I

Define a bolt pre-load for a bolt modeled with beam elements (Abaqus)

Define a bolt pre-load (ANSYS)

Learn more

Bolt pre-load

Bolt pre-loads with Simcenter Nastran and Simcenter 3D Multiphysics

Pre-loaded bolts modeled with solid elements (Nastran)

Bolt pre-loads with Abaqus

Constraining bolts to their pre-loaded lengths (Abaqus)

Pre-loaded bolts modeled with solid elements (Abaqus)

Pre-loaded bolts modeled with beam elements (Abaqus)

Bolt pre-loads with ANSYS

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Pre-loaded bolts modeled with beam elements (Nastran), Simcenter 3D 2021.1 Series

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