Seam weld universal connections in the LS-DYNA environment

In the LS-DYNA environment, you can use the universal connection commands to define and mesh seam weld connections between components. Pre/Post uses:

• ELEMENT_BEAM elements represent the seam weld connection.

• The LS-DYNA *CONTACT_SPOTWELD keyword to model the interaction between the seam weld elements and the connected components.

Defining the seam weld connection and generating the elements

• You can use the Seam Weld Connection command to specify the definition for the seam weld connection. For example, you specify the parts (flanges) to connect, the locations of the connections, tolerance values for creating the connections, and properties of the connection such as the diameter of the welds and the weld material.

• You can use either the Automatic Elements or Connection Elements commands to generate the actual seam weld elements from the connection definitions.If you use the Automatic Elements command, the software uses default values to create the seam weld elements.Note: You can use options on the Seam Weld page of the Universal Connections customer defaults to control those default values.If you use the Connection Elements command, you can use options in the Seam Weld Element dialog box to control how the software creates the seam weld elements.

Meshing LS-DYNA seam weld connections

The software always creates ELEMENT_BEAM elements to mesh seam weld connection definitions in the LS-DYNA environment.

If you change the specified solver environment to Nastran after you generate the seam weld elements, the software converts the ELEMENT_BEAM+CONTACT_SPOTWELD elements as shown below when you use the Update Finite Element Model command.

LS-DYNA	Nastran
ELEMENT_BEAM+CONTACT_SPOTWELD	CBAR+RBE3 Spider(s)

Mesh associated data for LS-DYNA seam weld elements

When you generate the seam weld connection elements, the software automatically defines the mesh associated data for the elements. In the Mesh Associated Data dialog box, the software automatically:

• Sets the Connection Options list to *CONTACT_SPOTWELD.

• Uses the LS-DYNA Parts for masters option to select the physical property tables, such as a PART (shell) or a PART (solid) table that are associated with the flanges to connect.

• Sets the CARD2/CARD3, CARDA, CARDB (optional), and Massively Parallel Processing Option (MPP) options to select the related modeling objects that you specified in the Seam Weld Element dialog box. For more information on these contact-specific options, see Specifying additional LS-DYNA contact properties.

Physical property data for LS-DYNA seam weld elements

During the meshing process, the software also creates a PART (beam) physical property table that defines the properties for the solid elements that represent the seam weld. In the PART (beam) dialog box, the software automatically:

• Sets the material to use for the seam weld. The software selects the Use Pre/Post Material check box in the Material Option group, sets the Material list to the material that you specified in the Adhesive Connection dialog box and sets the Material Type, which controls how the software exports the material property data to the LS-DYNA input file to Defined by Pre/Post.

• Specifies the SECTION_BEAM modeling object to use to define properties for the beam, with default settings that you can modify. The Fore Section option on the (Card 2) tab of the SECTION_BEAM dialog box references the appropriate Seam Weld Connection cross section. The SECTION_BEAM option corresponds to the *SECTION_BEAM keyword.

LS-DYNA seam weld elements in the Simulation Navigator

The software stores the seam weld connection elements as a new mesh in the appropriate PART (beam) entry in the 1D Collectors node in the Simulation Navigator. If your model contains multiple seam weld connection definitions that use different materials, the software places the elements into separate meshes in different PART (beam) entries.

Mesh for LS-DYNA seam weld elements in the Simulation Navigator

Solver syntax for LS-DYNA seam weld elements

When you export an LS-DYNA solution, Pre/Post writes out the seam weld element information to the LS-DYNA input file using the *ELEMENT_BEAM, *CONTACT_SPOTWELD, and *SET_PART keywords. For example:

$ ------------------- ELEMENTS -------------------$*ELEMENT_BEAM_ORIENTATION$    eid     pid      n1      n2      n3     rt1     rr1     rt2     rr2   local$       vx        vy        vz     684       7     918     919       0       0       0       0       0       2 0.000E+00 1.000E+00 0.000E+00     685       7     920     921       0       0       0       0       0       2 0.000E+00 1.000E+00 0.000E+00     686       7     922     923       0       0       0       0       0       2 0.000E+00 1.000E+00 0.000E+00     687       7     924     925       0       0       0       0       0       2 0.000E+00 1.000E+00 0.000E+00     688       7     926     927       0       0       0       0       0       2 0.000E+00 1.000E+00 0.000E+00     689       7     928     929       0       0       0       0       0       2 0.000E+00 1.000E+00 0.000E+00     690       7     930     931       0       0       0       0       0       2 0.000E+00 1.000E+00 0.000E+00 *SET_PART         1         7*SET_PART         2         3         4*CONTACT_SPOTWELD_ID         1 PART (beam)1$Card1 ssid     msid     sstyp     mstyp    sboxid    mboxid       spr       mpr         1         2         2         2                             0         0$Card2  fs        fd        dc        vc       vdc    penchk        bt        dt                                                                                $Card3 sfs       sfm       sst       mst      sfst      sfmt       fsf       vsf

Where do I find it?

Application	Pre/Post
Prerequisite	A FEM or assembly FEM file as the work part and displayed partLS-DYNA as the specified solver
Command Finder	Seam Weld Connection Connection Elements Automatic Connection Elements

Seam weld universal connection customer defaults

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

Learn more

Seam weld universal connections in the Nastran environment

User defined seam weld fine models

Seam weld visualization

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Seam weld universal connections in the LS-DYNA environment, Simcenter 3D 2021.1 Series

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