Meshing LS-DYNA bolt connections rigid body and beam elements

In the LS-DYNA environment, when you generate bolt elements from bolt universal connection definitions, you can select the CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) option to use:

• Beam elements in a spider configuration to connect the components.

• A rigid body (*CONSTRAINED_RIGID_BODY keyword) to define the interaction between the elements and the components.

Meshing a bolt connection with the CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) option

When you generate bolt elements with the CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) option, the software creates multiple spider-like rigid body elements for each bolt definition. It connects the legs of the element to the nodes on the target flanges. When you export the solution, Pre/Post uses the *SET_NODE keyword to write out the pairs of connected nodes.

Bolt meshed with the CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) option	Side view of the CONSTRAINED_NODAL_RIGID_BODY Spider(s) bolt element

Mesh associated data for the CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) option

When you generate bolt elements with the CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) option, the software uses the *CONSTRAINED_RIGID_BODY keyword to define a master-slave relationship between the flanges. In the Mesh Associated Data dialog box, the software automatically:

• Sets the Connection Options list to *CONSTRAINED_RIGID_BODIES.

• Uses the LS-DYNA Parts for slaves option to select the physical property tables that are associated with the flanges to connect.

Physical property data for the CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) option

During the meshing process with the CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) option, the software also creates a PART (beam) physical property table that defines the properties for the beam. In the PART (beam) physical property table dialog box, the software:

• Sets the material to use for the bolt. 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 Bolt 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.

• A circular Bolt Connection 1D beam cross section that defines the shape and radius of the beam element.

• The SECTION_BEAM modeling object to use to define properties for the beam, with default settings that you can modify. The Fore Section option in the SECTION_BEAM dialog box references the appropriate Bolt Connection cross section. The SECTION_BEAM option corresponds to the *SECTION_BEAM keyword.

CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) elements in the Simulation Navigator

How the software generates the bolt elements depends on how you created the bolt definition.

• If the bolt definition connects multiple flanges, the software creates two separate 1D meshes in separate mesh collectors.One mesh contains the spider element for the flange on which the head of the bolt is defined.The other mesh contains all other spider elements that connect the shank of the bolt to the other flanges.

• If the bolt definition contains multiple bolt locations, with each bolt possibly connecting different flanges, the software creates separate 1D meshes in separate mesh collectors for each bolt. Each mesh contains a pair of master-slave spider beam elements at each location.

Solver syntax for CONSTRAINED_RIGID_BODY +ELEMENT_BEAM Spider(s) elements

When you export an LS-DYNA solution, the software uses the *ELEMENT_BEAM and *NODE keywords to write out the data for the beam elements. For example:

$ Units: mm (milli-newton) (deg Celsius)$$ ------------------- ELEMENTS -------------------$*ELEMENT_BEAM_ORIENTATION$    eid     pid      n1      n2      n3     rt1     rr1     rt2     rr2   local$       vx        vy        vz    1825       4    2130     945       0       0       0       0       0       2 2.335E-09 1.000E+00 0.000E+00    1826       4    2130     946       0       0       0       0       0       2 4.067E-01 9.135E-01 0.000E+00    1827       4    2130     947       0       0       0       0       0       2 7.431E-01 6.691E-01 0.000E+00    1828       4    2130     948       0       0       0       0       0       2 9.511E-01 3.090E-01 0.000E+00    1829       4    2130     949       0       0       0       0       0       2 9.945E-01-1.045E-01 0.000E+00    1830       4    2130     950       0       0       0       0       0       2 8.660E-01-5.000E-01 0.000E+00    1831       4    2130     951       0       0       0       0       0       2 5.878E-01-8.090E-01 1.726E-15    1832       4    2130     952       0       0       0       0       0       2 2.079E-01-9.781E-01 2.668E-15    1833       4    2130     953       0       0       0       0       0       2-2.079E-01-9.781E-01 2.668E-15    1834       4    2130     954       0       0       0       0       0       2-5.878E-01-8.090E-01 0.000E+00    1835       4    2130     955       0       0       0       0       0       2-8.660E-01-5.000E-01 0.000E+00    1836       4    2130     956       0       0       0       0       0       2-9.945E-01-1.045E-01 0.000E+00    1837       4    2130     957       0       0       0       0       0       2-9.511E-01 3.090E-01 0.000E+00    1838       4    2130     958       0       0       0       0       0       2-7.431E-01 6.691E-01 0.000E+00    1839       4    2130     959       0       0       0       0       0       2-4.067E-01 9.135E-01 0.000E+00$$ ------------------- NODES -------------------$*NODE$    nid               x               y               z      tc      rc     945 4.332282543E+01 3.000000000E+01-2.400000000E+01       0       0     946 4.222722125E+01 2.484606278E+01-2.400000000E+01       0       0     947 3.913023087E+01 2.058342048E+01-2.400000000E+01       0       0     948 3.456710486E+01 1.794878574E+01-2.400000000E+01       0       0     949 2.932685882E+01 1.739811215E+01-2.400000000E+01       0       0     950 2.431582410E+01 1.902629749E+01-2.400000000E+01       0       0     951 2.040005232E+01 2.255193859E+01-2.400000000E+01       0       0     952 1.825700584E+01 2.736554330E+01-2.400000000E+01       0       0     953 1.825700688E+01 3.263445720E+01-2.400000000E+01       0       0     954 2.040005136E+01 3.744805966E+01-2.400000000E+01       0       0     955 2.431582316E+01 4.097370524E+01-2.400000000E+01       0       0     956 2.932686010E+01 4.260188659E+01-2.400000000E+01       0       0     957 3.456710411E+01 4.205121480E+01-2.400000000E+01       0       0     958 3.913023096E+01 3.941657959E+01-2.400000000E+01       0       0     959 4.222722129E+01 3.515393721E+01-2.400000000E+01       0       0    2130 3.065142810E+01 3.000000003E+01-2.400000000E+01       0       0

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	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

Extending the legs of spider elements in bolt connections

Bolt universal connections in the Nastran environment

Bolt universal connections in the LS-DYNA environment

Meshing LS-DYNA bolt connections with rigid body elements

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

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Meshing LS-DYNA bolt connections rigid body and beam elements, Simcenter 3D 2021.1 Series

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