LL-DYNA3D Interface

This interface writes global parameter definitions, coordinates, connectivity, property information & boundary conditions in the LL-DYNA3D input deck (keyword format).

Creating the LL-DYNA3D Input File

The translator writes the LL-DYNA3D input deck using the following files:

To create the LL-DYNA3D input file, select the following menu entries from the ICEM CFD/CAE manager:

 

Note:  The solver parameter file should be generated by loading LL-DYNA3D params menu, setting the solver parameter values and pressing <Accept> button, before using the write input menu.

         Select an existing unstructured domain file

         Give the name of its corresponding boundary condition file (default is configuration/mesh/family_boco)

         Give the name of its corresponding parameter file (default is configuration/mesh/ll_dyna3d.par)

         Specify whether to write Shell (2-D) elements (default yes).

         Specify whether to write Beam (1-D) elements (default yes).

         Give the name of the LL-DYNA3D input file (default is configuration/transfer/ll_dyna3d)

The successful execution of the interface generates the LL-DYNA3D input file located in the Transfer Shell. The ICEM CFD/CAE Manager opens a shell window in this directory when the following menu item is selected:

Note: If you have specified No Bar and No Shell conditions, Beam and Shell elements will not be written to the LL-DYNA input deck.

Defining parameters for LL-DYNA3D

The next sections describe how to define Default LL-DYNA3D keywords using the Output/ll_dyna3d param menu in the mesh editor (MED).

 
The coordinates, connectivity and property information in the LL-DYNA3D input deck is generated based on the settings that appear in following table. The table shows element types supported by Shells and Beams and respective materials.
 

Element Types

 

 Shells

Hughes-Liu, Belytschko-TsayBCIZ (triangle), C0 (triangle), Membrane, YASE, YASE (fully-integrated), Bathe-Dvorkin (fully-integrated)

 Beams

 Hughes-Liu, Belytschko-Schwer, Truss

 

Default Element: -
Default element types specified in the params pane are applied to shell and beams. Default elements are taken for solid. You can override element properties using LLDYNA Boundary condition menu.
 

Default Materials: -

Default materials can be specified for beams and shells. When user will select Element Type, corresponding material choice box will be enabled. Select the material from options available and specify parameters for the same. Material ID will be generated automatically.

Node Definition: -
Nodes will appear in the LL-DYNA3D input deck without any special attention from the user. However, fixed displacements and rotations can be applied to nodes and these will appear on the node definitions. For more details see the Fixed Node Displacements and Rotations section in the LLDYNA Boundary condition section defined below. 

 
Define Load Curve: -

Define a curve (e.g. load vs. time) and specify required parameters. Enter / Select values for parameters. Put one pair of points per card. For this card specify Abscissa values and Ordinate values. You can specify any number of points for a curve.

 

Defining boundary conditions for LL-DYNA3D

The next sections describe how to define LL-DYNA3D keywords using the Output/Bound conds menu in the mesh editor (MED).

Note:  The left pane of the menu displays families grouped according to the element dimensions. If any families appear under the type Mixed/unknown, these families should be split into more families so that each new family contains elements having same dimension.


Fixed Node Displacements and Rotations: -

Select Displacement and Rotational constraints for the selected family. If some of the nodes exist on two families, these constraints will be cumulative. If, for example, two separate BOUND cards are used which apply to the same node and which constrain displacements in X and Y respectively, the code for the affected node will be output automatically as 4 (constrained not to move in/about X, Y).

 

Element Properties for Solids, Shells and Beams: -

This boundary condition will override default element properties. If material type is not specified for the family, material type 1 will be applied to this family with given element properties. This boundary condition can be applied once to a family.

 

Define Material Properties: -

Define material types to the selected family. Apply material types depending upon elements in that family. Corresponding Hourglass stabilization can be included. Material types supported for respective elements at present in ll_dyna3d are shown in the following table.

 

Element

Type

Material Type

Elastic

(Type 1)

Orthotropic Elastic

(Type 2)

Kinematics/Isotropic Elastic-Plastic

(Type 3)

Johnson/Cook Elastic-Plastic (Type 15)

Compressible Mooney-Rivlin Hyper elastic Rubber (Type 27)

Brick

Applicable

Applicable

Applicable

Applicable

Applicable

Beam

Applicable

Not Applicable

Applicable

Not Applicable

Not Applicable

Shell

Applicable

Applicable

Applicable

Applicable

Not Applicable

 

This boundary condition can be applied once to a family.

 

Discrete Springs and Dampers: -

This condition can be applied to 1-D families only. Apply discrete springs and dampers elements to the selected family. Enter values for the specified parameters. This feature allows LL-DYNA to be used to solve simple spring-mass models, or to couple these simple models with complex finite element models.

 

Lumped Mass: -

This condition can be applied to all families. Define Lumped Mass element to the selected family. Enter the values for the specified parameters. These element properties will be applied to each element in that family.

 

Pressure Loads: -

Define pressure load to the selected family. Pressure loads can be applied to solid and shell elements. For solid elements the normal direction is calculated automatically depending upon element type. But for shell elements (surface families), normal direction can be inward or outward. If the user wants normal direction to be correct one for each element in the surface, specify an extra input for volume family (adjacent to surface). Then all elements in the surface family will have normal direction same as that of volume elements (i.e. outward). You can specify default direction or direction same as that of solid elements in the neighbors.

 

Sliding Interface:-

This condition is only applied to shell elements (surface families). Define sliding interface between master and slave surface families. Family on which you are applying this boundary condition will be considered as slave family. For specifying direction of normal for surface elements, specify an extra input for volume family. Elements will be written in the same order as that of neighboring volume family’s element (solid) nodes of face common to both solid and shell element.

Note: - Sliding interface types 1-10 are supported.