LS-DYNA Solver Interface 8.0 Tutorials

HyperMesh 8.0 Tutorials

LS-DYNA Solver Interface

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HyperMesh 8.0 Tutorials

LS-DYNA Solver Interface

General Introduction to HyperMesh - DYNA Interface - HM-4600 ... 1

Defining LS-DYNA Model and Load Data, Controls, and Output - HM-4605 ... 5

Using Curves, Beams, Rigid Bodies Joints, and Loads in DYNA - HM-4610... 20

Model Importing, Airbags, Exporting Displayed, and Contacts using

DYNA - HM-4615... 38

Rigid Wall, Model Data, Constraints, and Output using DYNA - HM-4620 ... 46

Assemblies using DYNA - HM-4625 ... 56

General Introduction to HyperMesh - DYNA Interface -

HM-4600

In this tutorial, you will learn to understand the following components of the LS-Dyna interface:

• LS-DYNA FE input reader

• LS-DYNA FE output template

• LS-DYNA macro menu

• LS-DYNA user profile

• On-line help for the HyperMesh DYNA interface

HyperMesh’s LS-Dyna FE input translator, FE output template, macro menu, and user profile sets the foundation for using LS -Dyna with HyperMesh.

Tools

DYNA Macro Menu

The DYNA macro menu contains tools specific to using DYNA with HyperMesh. The menu has eight pages of tools. The pages and some menu tools are described below.

Page Page description

Geom/Mesh Contains a set of macros related to working with model geometry, as well as a set for working with FE mesh.

User For user-defined macros.

Disp Contains a variety of macros that allow you to modify the graphical display of HyperMesh entities in several different ways such as: turn the display of individual entity types on and off, isolate only a specific entity type, or turn off the display of everything except entities of type.

QA/Model Contains many tools to help you quickly review and clean up the quality of a pre-existing mesh.

Tools in the Tools page of the DYNA macro menu

Error check Checks your LS -DYNA deck for potential problems with components, properties, materials, rigids, joints, boundary conditions, and other entities and reports them on-screen. The report identifies the problem entity by ID, describes the error, and then enables you to isolate the entity in the model.

Part info Summarizes a part’s statistics in a dialog.

Name mapping Provides the ability to change names for various entity types to either the HyperMesh name or the LS -DYNA name, since both applications

Tools in the Tools page of the DYNA macro menu

Create part Creates a new part, with the option of either creating new or reusing existing Section and Material properties through a single panel.

Part Replacement Allows you to replace the elements in an existing component (*PART) with new elements; typically replacing a similar part remeshed or slightly reshaped.

Constrained Rgd Body

Summarize all the *CONSTRAINED_RIGID_BODIES and visualize the master and slave rigid bodies

Convert To Rigid Converts a portion or whole model to rigid; creates *CONSTRAINED_RIGID_BODIES

Find Free Identifies rigids and welds that have a free end

Find_Fix Free Removes free ends of rigids and welds

Fix Incorrect Merges *CONSTRAINED_NODAL_RIGID_BODIES that share common nodes

RLs with Sets *CONSTRAINED_NODAL_RIGID_BODIES in HyperMesh 5.0 and older binary files updated to have a *SET_NODE_LIST (entity set). This allows you to have control over the set IDs.

Content Table Summarize, create, and edit parts, sections in the model

Material Table Summarize, create, and edit materials in the model

C-Interfto50 Converts display of DYNA contacts to HyperMesh 5.0 style for DYNA models created from HyperMesh 5.1 Release (no HyperMesh 5.1 DYNA update installed)

On-line Help

HyperMesh on-line help describes how to create every supported DYNA card. To access the on-line help do the following:

• From the Help menu, click Interfaces. On the Contents tab in the pop-up window, go to Solver Interfacing in HyperWorks à LS-DYNA à HyperMesh à Supported LS-DYNA Keywords

DYNA FE Input Translator

The DYNA FE input translator imports DYNA input files. Two translators exist:

FE input reader Supported DYNA input file

DYNA KEY Version 960 and 970 keyword format

DYNA SEQ Version 936 sequential format

• Select an input translator.

• To import a DYNA input file, do one of the following:

o Go to the File menu and point to Import, then point to Finite Element Model, and click LsDyna.

o Click the file icon , go to the import sub-panel, and select FE

DYNA FE Output Template

A DYNA FE output template contains DYNA -specific formatting instructions that HyperMesh uses to create a DYNA input file. Several DYNA templates exist:

FE output template DYNA input file generated from template

ls-dyna\dyna.key _{Version 970 keyword format}

ls-dyna\curves.key Version 970 keyword format for curves only ls-dyna960\dyna.key _{Version 960 keyword format}

ls-dyna960\curves.key _{Version 960 keyword format for curves only} ls-dyna_seq\dyna.seq _{Version 936 sequential format}

ls-dyna_seq\dyna.lrg _{Version 936 sequential, large format}

ls-dyna_seq\curves.seq _{Version 960 sequential format for curves only} These templates are in the folder ALTAIR_HOME\templates\feoutput.

• To select an output template, do one of the following:

o Click the file icon , go to the export sub-panel, select TEMPLATE, and click

load

o Press G on the keyboard to go to the Global panel and click Load.

DYNA User Profile

To set the user profile, go to the Preferences menu and click User Profiles. Setting the user profile to DYNA saves you time and does the following:

• Sets the FE input reader to DYNA KEY;

• Loads the dyna.key FE output template and DYNA macro menu;

• Loads DYNA macro menu

• Aligns the graphical user interface to focus on DYNA tools; Re-names and removes certain panels;

• Enables the ALE setup panel.

Changing the DYNA user profile to another profile, such as OptiStruct, does not alter the DYNA model.

Defining LS-DYNA Model and Load Data, Controls, and

Output - HM-4605

In this tutorial, you will learn to:

• View DYNA keywords in HyperMesh as they will appear in the exported DYNA input file

• Understand part, material, and section creation and element organization

• Create sets

• Create velocities

• Understand the relation of DYNA entity type to HyperMesh element and load configurations

• Create nodal single point constraints

• Create contacts with set segment ID

• Define output and termination

• Export models to LS-DYNA formatted input files

Tools/Utilities

• LS-Dyna FE input translator

• FE output template

• LS-Dyna macro menu

• User Profile

The above tools/utilities set the foundation for settings up an Ls-Dyna input deck with HyperMesh.

Exercises

This tutorial contains the following exercises:

Exercise 1: Define Boundary Conditions and Loads for the Head and A-Pillar Impact Analysis Exercise 2: Define Termination and Output for the Head and A-Pillar Impact Analysis

Section 1: Define Model Data

Relation of *PART, *ELEMENT, *MAT, and *SECTION to Each Other

*PART PID SID MID *SECTION SID

A *PART shares attributes such as section properties (*SECTION) and a material model (*MAT). A group of elements (*ELEMENT) sharing common attributes generally share a common part id (PID). The figure below shows how the keywords *PART, *ELEMENT, *MAT and *SECTION relate to each other. A unique PID assigns a material id (MID) and a section id (SID) to an element.

The figure below shows how the keywords *ELEMENT, *PART, *SECTION, and *MAT are organized in HyperMesh.

*ELEMENT EID PID Elements are organized into a component collector

*PART PID SID MID Component collector’s card image

*SECTION SID Property collector with a property card image. Assign a property to a *PART by pointing to the property collector in the component collector’s card image.

*MAT MID Material collector with a material card image.

Assign the material to the *PART by associating the material collector to the component collector. Component, property and material collectors are created and edited from the collectors panel.

View DYNA Keywords in HyperMesh

A HyperMesh card image allows you to view the image of keywords and data lines for defined DYNA entities as interpreted by the loaded template. The keywords and data lines appear in the exported DYNA input file as you see them in the card images. Additionally, for some card images, you can define and edit various parameters and data items for the corresponding DYNA keyword. Card image can be viewed using the Card Editor panel which can be accessed from either the

Setup menu or from the Analysis page.

Create *MAT

In HyperMesh, a *MAT is a material collector with a card image. To relate it to a *PART, the material collector is associated to a component collector. A material collector can be created from the Solver

Browser or the Organize menu.

Update a Component’s Material

Update any component with any material from the collectors panel, update sub-panel.

Material Table Utility

This utility allows users to do the following:

• View a list of all existing materials in the model and attributes for them.

• Create, edit, merge and check for duplicate materials.

Create *SECTION

In HyperMesh, *SECTION is a property collector with a card image. This is created in the collectors panel, create sub-panel.

Exercise 1: Define Model Data for the Head and A-Pillar Impact

Analysis.

The purpose for this exercise is to help you become familiar with defining LS -DYNA materials, sections and parts using HyperMesh.

This exercise comprises of setting up the model data for an LS -DYNA analysis of a hybrid III dummy head impacting an A-pillar. The head and A-pillar model is depicted below.

Head and A-pillar model (Ch2_Image1.tif) This exercise contains the following tasks.

• Define the material *MAT_ELASTIC for the A-pillar part and head part.

• Define *SECTION_SHELL for the A-pillar.

• Define *SECTION_SOLID for the head.

• Define *PART for the A-pillar and the head.

Step 1: Load the LS-DYNA user profile .

Step 2: Retrieve the HyperMesh file head_start.hm.

• From File menu, point to Import, click on Hypermesh Model and select the .hm file.

• From toolbar, click the Files icon - Select hm file sub-panel – Click retrieve… and select the .hm file

2. Click return to go to the main menu.

Step 3: Define the material *MAT_ELASTIC for the A-pillar and head.

• From the Organize menu, click Collectors

• From the toolbar, click collectors 2. Go to create sub-panel.

3. Set the collector type to materials. 4. For name =, type elastic

5. For card image =, select MATL1.

6. Click create/edit to create the material and edit its card image. 7. Click the [Rho] field and enter 1.2 E-6 for the density. 8. For Young’s modulus [E], specify 210.

9. For Poisson’s ratio [Nu], specify 0.26. 10. Click return to go to the collectors panel. 11. Remain in the collectors panel for the next step.

Step 4: Define *SECTION_SHELL with a thickness of 3.5 mm for the A-pillar.

2. For name =, type section3.5. 3. For card image =, select SectShll. 4. For thickness =, enter 3.5

5. Create/edit the property.

Notice that a thickness (T1) of 3.5 is assigned to *SECTION_SHELL card. 6. Return to the collectors panel.

Step 5: Define *SECTION_SOLID for the head.

2. For card image =, select SectSld. 3. Create/Edit the property.

4. Return to the collectors panel. 5. Return to the main menu.

Step 6: Define *PART for the A-pillar. It’s *MAT_ELASTIC is the material

collector named "elastic". Its *SECTION_SHELL is the property collector

named "section3.5".

1. Go to the collectors panel. 2. Go to update sub-panel. 3. Set the collector to comps.

4. With the comps selector active, select the component pillar. 5. For card image =, select Part.

6. For material =, select elastic. 7. For property =, select section3.5. 8. Click update/edit.

Notice that a *PART has been created and a section (SID) and a material (MID) has been assigned to it.

9. Return to the collectors panel.

10. Remain in the collectors panel for the next step.

Step 7: Define *PART for the head. It’s *MAT_ELASTIC is the material collector

named "elastic". Its *SECTION_SOLID is the property collector named "solid".

2. For card image =, select Part. 3. For material =, select elastic. 4. For property =, select solid. 5. Click update/edit.

Notice that a *PART has been created and a section (SID) and a material (MID) has been assigned to it.

Step 8 (Optional): The exercise is complete. Save your work to a HyperMesh

file.

Section 2: Define Boundary Conditions and Loads

*INITIAL_VELOCITY_(Option)

The table below describes DYNA keywords for defining initial velocity.

DYNA keyword Velocity applied to … Setup in HyperMesh

*INITIAL_VELOCITY set of nodes, *SET_NODE_LIST

Entity set of nodes,

load collector with InitialVel card image

*INITIAL_VELOCITY_GENE RATION

one *PART or set of parts, *SET_PART_LIST

Entity set of comps,

load collector with InitialVel card image

*INITIAL_VELOCITY_NODE individual nodes Created from velocity panel, organized in load collector with no card image

*SET

With the exception of *SET_SEGMENT, all *SET types are created from the entity sets panel in the

BCs page. Graphically view a set’s contents with the review function in the entity sets panel.

*SET_SEGMENT is created from the set_segments panel and is discussed in this chapter.

HyperMesh Entity Configurations and Types

HyperMesh elements and loads have two identifiers: configuration and type. Configuration is a HyperMesh core feature. Type is defined by the loaded FE output template. A configuration can support multiple types. Before creating elements or loads, select the desired type from either the

elem types panel (in the 1D, 2D and 3D pages) or the load types panel (in the BCs page).

Use the load types panel only when creating loads directly on nodes or elements. For all other cases, the load is defined by creating a load collector with a card image. For example,

*INITIAL_VELOCITY_NODE (applied directly to nodes) is created from the velocities panel while *INITIAL_VELOCITY (applied to nodes in a set) is a load collector with the InitialVel card image. You can see a list of element and load configurations in the elem types panel and the load types panel, respectively. These panels are pictured below.

elem types panel

load types panel

Some element configurations are rigid and quad4. When a dyna.key template is loaded, types of the rigid configuration are RgdBody, ConNode and GenWeld

(*CONSTRAINED_NODAL_RIGID_BODY, *CONSTRAINED_NODE_SET and *CONSTRAINED_GENERALIZED_WELD_SPOT).

Similarly, some load configurations are force and pressure. Types of the pressure configuration are

ShellPres and SegmentPre (*LOAD_SHELL_ELEMENT and *LOAD_SEGMENT).

Most element and load configurations have their own panels. For example, rigids are created from the

rigids panel and constraints are created from the constraints panel.

*BOUNDARY_SPC_(Option)

The table below describes DYNA keywords for defining nodal single point constraints.

DYNA keyword Constraint applied to … Setup in HyperMesh

*BOUNDARY_SPC_NODE individual nodes These are constraints created from the constraints panel and organized into a load collector with no card image.

*BOUNDARY_SPC_SET a set of nodes *SET_NODE_LIST

This is an entity set of nodes referenced in a load collector’s

BoundSpcSet card image.

*CONTACT and *SET_SEGMENT

With the exception of *CONTACT_ENTITY, DYNA contacts are created from the interfaces panel in the Tool page. (*CONTACT_ENTITY is created from the rigid walls panel in the same page.) A DYNA contact is a HyperMesh group. When you want to manipulate a *CONTACT such as delete, renumber, or display it off, you select groups.

DYNA Contact Master and Slave Types

DYNA has multiple contact master and slave types from which to choose. The table below lists these types. While HyperMesh supports all of them, this chapter focuses on contacts with slave and master type 0, set segment id. Chapter three focuses on the other slave and master types.

*SET_SEGMENT and set_segment Panel

*SET_SEGMENT is created from the set_segment (contactsurfs) panel. (The panel is named

set_segment when the DYNA user profile is loaded.) Additionally, from this panel, you can add and

remove elements from an existing *SET_SEGMENT and adjust the normal of segments without adjusting the normal of elements.

The graphical representation of a contactsurf is pyramids, one pyramid for each segment. The orientation of a pyramid represents the normal orientation of the segment. By default, the orientation of a pyramid is the same as the normal of the element underneath.

In the set_segment panel is the word contactsurfs and not the word set_segment. This is because contactsurfs is a HyperMesh configuration while set_segment is only the name of the panel for the DYNA user profile. This is important to know because when you want to manipulate a

*SET_SEGMENT, such as delete, renumber, or display it off, you will select contactsurfs and not set_segment.

A *SET_SEGMENT is specified in a *CONTACT from the interfaces panel, add sub-panel with

Exercise 1: Define Boundary Conditions and Loads for the Head

and A-Pillar Impact Analysis .

The purpose for this exercise is to help you start becoming familiar with defining LS -DYNA boundary conditions, loads and contacts using HyperMesh.

This exercise comprises of setting up the boundary conditions and loads data for an LS-DYNA analysis of a hybrid III dummy head impacting an A-pillar. The head and A-pillar model is depicted below.

Head and A-pillar model (Ch2_Image1.tif) This exercise contains the following three tasks.

• Define velocity on all nodes of the head with *INITIAL_VELOCITY

• Constrain the pillar’s end nodes in all six degrees of freedom with *BOUNDARY_SPC_NODE

• Define a contact between the head and A-pillar with *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE

Step 1: Make sure the LS-DYNA user profile is still loaded.

Step 3: Create a node set, *SET_NODE_LIST, containing all the nodes in the

head

component.

1. Access the entity sets panel in one of the following ways:

• From the Setup menu, click Entity Sets

• From the Analysis page, click entity sets 2. For name =, type Vel_Nodes.

3. For card image. Select Node.

4. With the nodes selector active, select nodes >> by collector and select the component head. 5. Create the set.

6. Return to the main menu.

Step 4: Define the velocity.

1. Enter the collectors panel, create sub-panel. 2. Set the collector type to loadcols.

3. For name =, type init_vel.

4. For the card image = select InitialVel.

5. Create/edit to create the load collector and edit its card image. 6. For the node set id [NSID] select the entity set Vel_Nodes. 7. For the initial velocity in the global x-direction, VX, specify 5. 8. Return to the collectors panel.

9. Stay in the collectors panel for the next step.

Step 5: Create a load collector for the constraints to be created.

1. For name = type SPC.

2. For creation method select no card image. 3. Optionally select a color for the load collector. 4. Create the load collector.

Step 6: Select BoundSPC for the HyperMesh constraint configuration.

• From the BCs menu, click Load Types

• From the Analysis page, click load types 2. For constraint = select BoundSPC.

3. Return to the main menu.

Step 7: Create constraints on the pillar’s end nodes.

• From the BCs menu, click Constraints

• From the Analysis page, click constraints 2. Go to create sub-panel.

3. Leave the entity selector set to nodes.

4. Select nodes >> by sets and select the pre-defined entity set nodes for SPC. Notice the nodes at the pillar’s ends are highlighted.

5. Leave all six degrees of freedom, dof1 thru dof6, active. 6. Create the constraints.

7. Return to the main menu.

Step 8: Define a *SET_SEGMENT for the slave entities, the A-pillar elements.

2. For name = type pillar_slave. 3. For the card image select setSegment. 4. Optionally select a color for the contactsurf.

5. With the elems selector active, select elems >> by collector and then select the pillar component.

6. Create the contactsurf.

7. Review the contactsurf to make sure its pyramids are pointing out of the pillar. 8. Stay in the set_segment panel for the next step.

Step 9: Define a *SET_SEGMENT for the master entities, the head elements.

5. With the elems selector active, select elems >> by collector and then select the head component.

6. Leave the toggle set to nodes on face.

7. Click the yellow nodes selector to make it active.

8. Select three nodes belonging to the same face of a solid element. 9. For the break angle, leave is set to 30.

10. Create the contactsurf.

11. Review the contactsurf to make sure its pyramids are pointing out of the head. 12. Return to the main menu.

Step 10: Create a HyperMesh group with the SurfaceToSurface card image.

• From the Setup menu, click Interfaces

• From the Analysis page, click interfaces 2. Go to create sub-panel.

3. For name = type contact.

4. For type = select SurfaceToSurface. 5. Create the group.

6. Stay in the interfaces panel for the next step.

Step 11: Add the slave and master contactsurfs to the HyperMesh group.

2. For the master type select csurfs.

3. Click the contactsurfs selector and select the head_master contactsurf. 4. Click update in the master: line, to the right of the yellow contactsurfs selector. 5. For the slave type select csurfs.

6. Click the contactsurfs selector in the slave: line and select pillar_slave. 7. Click update in the slave: line.

8. Stay in the interfaces panel for the next step.

Step 12: Edit the group’s card image to define the AUTOMATIC option.

2. Edit the group’s card image. 3. Under Options, select Automatic. 4. Return to the main menu.

Step 13: Review the group’s master and slave surfaces.

2. For name =, select contact. 3. Click review.

Notice the master and slave entities are temporarily displayed blue and red, respectively. 4. Return to the main menu.

Step 14 (Optional): The exercise is complete. Save your work to a HyperMesh

file.

Section 3: Define Control Cards and Specify Output

*CONTROL and *DATABASE

The *CONTROL cards are optional and can be used to change defaults and activate solution options, such as mass scaling, adaptive meshing and an implicit solution. It is advisable to define

*CONTROL_TERMINATION in a model to specify a job’s end time.

The *DATABASE cards are optional, but are necessary to obtain output files containing results. In HyperMesh, with the exception of the cards listed in the table below, all *CONTROL and *DATABASE cards are created from the control cards panel from either the Setup menu or the

Analysis page.

*DATABASE cards NOT created from control cards panel

DYNA card Panel used to create card

*DATABASE_CROSS_SECTION_(Option) PLANE option, rigid walls panel SET option, interfaces panel

*DATABASE_HISTORY_(Option) output blocks panel

*DATABASE_NODAL_FORCE_GROUP interfaces panel

Exercise 2: Define Termination and Output for the Head and

A-Pillar Impact Analysis.

The purpose for this exercise is to help you becoming familiar with defining LS-DYNA control data and output requests using HyperMesh.

This exercise comprises of defining the termination and output for an LS-DYNA analysis of a hybrid III dummy head impacting an A-pillar. The head and A-pillar model is shown in the image below.

Head and A-pillar model (Ch2_Image1.tif) This exercise contains the following four tasks.

• Specify the time at which LS-DYNA is to stop the analysis with *CONTROL_TERMINATION

• Specify ASCII output with *DATABASE_(Option) cards

• Specify the output of d3plot files with *DATABASE_BINARY_D3PLOT

• Export the model to an LS -DYNA 970 formatted input file

Step 1: Make sure the LS-DYNA user profile is still loaded.

Step 2: Retrieve the HyperMesh file head_3.hm.

Step 3: Specify the time at which you want LS-DYNA to stop the analysis with

*CONTROL_TERMINATION.

1. The control cards panel can be accessed by one of the following ways,

• From the Setup menu, click Control Cards

• From the Analysis page, click control cards 2. Go to the next, next page.

3. Select CONTROL_TERMINATION. A card image pops up.

4. For the termination time of the analysis, ENDTIM , specify 2.5. 5. Return to the control cards panel.

Step 4: Specify the output of d3plot files with *DATABASE_BINARY_D3PLOT.

2. Select DATABASE_BINARY_D3PLOT

3. For the interval between outputs in the D3PLOT file, [DT], specify 0.1. 4. Return to the control cards panel.

Step 5: Specify ASCII output with *DATABASE_(Option) cards.

2. Select DATABASE_OPTION.

3. For the GLSTAT file, [GLSTAT], specify 0.1.

This specifies the output of global data at every 0.1 ms. 4. For the MATSUM file, [MATSUM], specify 0.1.

This specifies the output of material energies every 0.1 ms. 5. For the SPCFORC file, [SPCFORC], specify 0.1.

This specifies the output of SPC reaction forces every 0.1 ms. 6. Return to the control cards panel.

7. Return to the main menu.

Step 6: Export the model as an Ls-Dyna keyword file.

4. Click return to go to the main menu.

Step 7 (Optional): Submit the LS-DYNA input file to LS-DYNA 970.

2. From the solvers menu, select Start LS-DYNA analysis. 3. Load the file head_complete.key.

4. Click OK to start the analysis.

Step 8 (Optional): Post-process the LS-DYNA results using HyperView.

Step 9 (Optional): The exercise is complete. Save your work to a HyperMesh

file.

Using Curves, Beams, Rigid Bodies Joints, and Loads in

DYNA - HM-4610

In this tutorial, you will learn how to:

• Create XY curves to define non-linear materials

• Define beam elements with HyperBeam

• Create constrained nodal rigid bodies

• Create joints

• Define *DEFORMABLE_TO_RIGID

• Define *LOAD_BODY

• Define *BOUNDARY_PRESCRIBED_MOTION_NODE

• Use the HyperMesh Content Table tool to review the model’s data

Tools

The following tools are covered in this tutorial:

• DYNA Tools

• Content Table

• Curve Editor

Dyna Tools menu can be accessed from the View menu >> Utility Menu.

Content Table is part of the DYNA Tools menu. With this tool, you can view a summary of the

model’s parts as well as create and edit parts. Below is a list of the tool's functionality.

• Create a list of displayed or all parts and view them in the graphics area

• Display parts with same section or material

• Rename and renumber parts, sections and materials

• Update thickness

• Create new parts

• Assign sections and materials to parts

• Export table to file with comma separated format

In the Content Table window, Place the mouse handle over the button to see an explanation of each button.

Curve Editor can be accessed by going to the Setup menu and click Curve Editor.

The curve editor is a pop-up window that allows you to view and modify graphed curves in a more intuitive and holistic way than the individual xy plots panels provide.

Below is a list of the tool’s functionality.

• Change curve attributes

• Change graph attributes

• Display curves in the graph area

• Create a new curve

• Delete a new curve

• Rename a curve

Below is a sample image of the Curve Editor.

Exercises

This tutorial contains the following exercises:

Exercise 1: Define Model Data for Seat Impact Analysis

Process

This section describes how to define model data.

*DEFINE_CURVE

*DEFINE_CURVE defines a curve. Curves are often used to define non-linear materials and loads. There are a few methods for creating DYNA curves in HyperMesh. A few methods are described below.

Method 1: Create using Curve Editor

From the Setup menu, click Curve Editor.

Method 2: Input XY Data from a File

Create *DEFINE_CURVE by inputting an XY dat a file from the read curves or edit curves panel in the xy plots module on the Post page. The figure below displays a sample XY data file with a format supported by these panels.

XYDATA, <curve one name> x1 y1

x2 y2 ENDDATA

XYDATA, <curve two name> x1 y1

x2 y2 ENDDATA

XY Data File Format

Engineers often receive test data in Excel file format. Data exported from Excel in comma or space delimited format can be read into HyperView. Data exported from HyperView in XY data format can be read into HyperMesh to create curves. In HyperView, from the Plot client, select Export Curves from the File pull-down menu. Select the XY Data format from the pop-up window.

Method 3: Create with Math Expressions

Create *DEFINE_CURVE with math expressions from the edit curves panel. From this panel, you can also create *DEFINE_CURVE with a math expression and an XY data file combination.

Plots

The HyperMesh naming convention for curves is curveN where N is a number. Curves are displayed in plots. Display on and off a curve by displaying on and off its plot from the Display panel in the Tool bar area.

Export Only XY Curves

Export only curves to a DYNA input file using one of the following templates from the files panel,

export sub-panel.

HyperMesh template DYNA input file generated from template

ls-dyna\curves.key Version 970 keyword format for curves only ls-dyna960\curves.key Version 960 keyword format for curves only

These templates are in the folder ALTAIR_HOME\templates\feoutput. Import the exported file into HyperMesh from the files panel, import sub-panel.

*DEFINE_TABLE

*DEFINE_TABLE defines a table. It consists of a *DEFINE_TABLE card followed by n lines of input. Each of the n additional lines define a numerical value in ascending order corresponding to a *DEFINE_CURVE input which follows the *DEFINE_TABLE command and the related input. In HyperMesh, *DEFINE_TABLE is created from a dummy *DEFINE_CURVE. Edit the dummy curve from the Card Editor panel. In the pop-up card image activate the DEFINE_TABLE option to create *DEFINE_TABLE and specify values and load curves. The figure below shows the *DEFINE_TABLE card image.

If, for example, ten stress-strain curves for ten different strain rates are given, HyperMesh will write ten cards to the DYNA input file after the first card for *DEFINE_TABLE. The ten corresponding *DEFINE_CURVE specifications will immediately follow in the exported input file.

Beam Elements

*ELEMENT_BEAM is created from the beams (bars) panel. (The panel is named beams when the DYNA user profile is loaded.) In this panel, you need to always specify node 3, which determines the initial configuration of the cross section. However, not every beam type requires node 3. You can suppress node 3 by card editing the beam elements from the Card Editor panel.

Beam elements are organized into a component collector with the Part card image. Specify the THICKNESS and PID options by card editing the beam elements from the Card Editor panel.

*SECTION_BEAM

*SECTION_BEAM is a property collector.

HyperBeam

HyperBeam supports *SECTION_BEAM when ELFORM is 2 or 3. The HyperBeam panel is located in the Geom page. HyperBeam allows you to create a beam cross-section entity and this is saved to the HyperMesh database as a beamsec. Select a beamsec from the *SECTION_BEAM card image to populate its fields A, Iss, Itt, and Irr.

Nodal Rigid Bodies

*CONSTRAINED_NODAL_RIGID_BODY can be created from Create Cards found under Tools menu. Below is an image of the rigids panel. When the panel option attach nodes as set is active, a *SET_NODE_LIST (entity set) containing all of the selected nodes is created. You can renumber the entity set from the renumbers panel. In the exported DYNA input file, the *SET_NODE_LIST immediately follows the *CONSTRAINED_NODAL_RIGID_BODY card.

Rigids panel

Joints

All DYNA joints are created from Create Cards found under Tools menu. They are organized into a component collector with no card image.

Unlike other 1D elements, you do not specify the DYNA joint type from the elem types panel. Rather, specify it in the panel used to create it, the fe joints panel.

In the fe joints panel is the property= selector. As a DYNA user, you can disregard this selector. If the HyperMesh user profile is loaded, the panel also has the orientation option. As a DYNA user, you can disregard this option also.

Coincident Node Picking

For DYNA joints, the nodal points in the nodal pairs should coincide in the initial configuration. The

coincident picking option can be turned on from the options panel, modeling sub-panel. It allows

you to graphically select a desired node from a stack of coincident nodes. This option also supports coincident picking for elements, loads, and systems.

Create Coincident Nodes

Create a node "like" an existing node from the create node panel in the Geom page. Select the type

in sub-panel. Click as node, select a node in the graphics area and then click create.

*CONSTRAINED_JOINT_STIFFNESS

*CONSTRAINED_JOINT_STIFFNESS_OPTION is a HyperMesh property collector with the JointStff card image.

*DEFORMABLE_TO_RIGID

The table below lists the DYNA *DEFORMABLE_TO_RIGID keywords.

DYNA keyword Purpose

*DEFORMABLE_TO_RIGID Switch parts to rigid at the start of the calculation *DEFORMABLE_TO_RIGID_A

UTOMATIC

Switch parts to rigid or to deformable at some state in the calculation

*DEFORMABLE_TO_RIGID_IN ERTIA

Define inertial properties for the new rigid bodies created when the deformable parts are switched

Below is the card format for specifying parts for these keywords:

1 2 3 4 5 6 7 8

PID MRB

PID is the ID of the slave part to be switched

MRB is the part ID of the master rigid body to which the part is merged. This field exists only for *DEFORMABLE_TO_RIGID and for

*DEFORMABLE_TO_RIGID_AUTOMATIC when the part is to be switched to rigid. In HyperMesh, rather than specify one part at a time, you specify an entity set containing all of the desired slave parts. On export, the entity set’s part IDs are written to the DYNA input file according to the above card format.

Exercise 1: Define Model Data for the Seat Impact Analysis.

This exercise is comprised of defining and reviewing model data for an LS-DYNA analysis of a vehicle seat impacting a rigid block. The seat and block model is shown in the image below.

Seat and block model

Step 1: Load the LS-DYNA user profile.

Step 2: Retrieve the HyperMesh file seat_start.hm.

Step 3: Create an xy plot.

1. Access the plot panel one of the following ways:

• From the Setup menu, point to XY plots, click Create Plots.

• From the Post page, click xy plots and select plots panel. 2. For name = type seat_mat.

3. Verify the plot type is set to standard. 4. Leave the like field empty.

When an existing plot is selected, the new plot adopts its attributes. 5. Create plot.

Step 4: Input data from a file to create two stress-strain curves.

• From the Setup menu, point to XY plots, click Read Curves.

• From the Post page, click xy plots and select read curves panel. 2. For plot =, leave it set to seat_mat.

3. Browse for the file named seat_mat_data.txt. 4. Input the file.

Notice two curves are created and are named 0.001 strain rate for steel (curve1) and

0.004 strain rate for steel (curve2).

5. Return to the xy plots module menu.

Step 5: Create a dummy xy curve to be used to create *DEFINE_TABLE.

• From the Setup menu, point to XY plots, click Edit Curves.

• From the Post page, click xy plots and select edit curves panel. 2. Go to the create sub-panel.

3. For plot = select seat_mat. 4. Activate the math option.

5. In the x= field enter {0.0, 0.2}. 6. In the y= field enter {0.4, 0.4}. 7. Create the curve.

Notice the curve is displayed in the seat_mat plot and has the name curve3. 8. Return to the main menu.

Step 6: Create *DEFINE_TABLE from the dummy curve.

• From the Setup menu, click Card Editor

• From the toolbar, click the card editor icon 2. Set the entity selector to curves.

3. Select curve3. 4. Edit the curve.

7. For the strain rate VALUE(1) specify 0.001. 8. For the strain rate VALUE(2) specify 0.004. 9. For CurveId(1) select curve1.

10. For CurveId(2) select curve2. 11. Return to the main menu.

Step 7: Create the non-linear material.

(*MAT_PIECEWISE_LINEAR_PLASTICITY)

1. Do one of the following to create any LS-Dyna keyword card:

• From the Tools menu, click Create Cards

• Right -click anywhere in Solver Browser window and click Create a new card 2. From the Ls -Dyna keyword list, point to *MAT.

3. Select *MAT_PIECEWISE_LINEAR_PLASTICITY. 4. For name = type steel and click OK.

Notice *MAT_PIECEWISE_LINEAR_PLASTICITY card is created. 5. For density [Rho] specify 7.8 E-6.

6. For Young’s Modulus [E] specify 200. 7. For Poisson’s ratio [NU] specify 0.3. 8. For yield stress [SIGY] specify 0.25.

9. For the *DEFINE_TABLE id [LCSS] specify the curve3 (id=5). 10. Return to the collectors panel.

11. Return to the main menu.

Step 8: Update the base_frame and back_frame components with the new

non-linear material.

1. Click on Content Table found under DYNA Tools in the Utility Menu. 2. From the Table menu, click Editable.

3. Select the components base_frame and back_frame. 4. For Assign Values:, select Material name

5. For HM -Mats:, select steel 6. Click Set.

7. Click Yes to confirm.

Steps 9-12: Create a beam element, *ELEMENT_BEAM, to complete the seat’s

back_frame connection to the side_frame on the left side.

Step 9: Restore a pre-defined view for ease of following the next steps.

A window pops up.

2. Click restore1 to see the beam view.

Step 10: Set the current component to beams.

This component has a pre-defined section, *SECTION_BEAM, with a tubular cross section associated to it.

3. Return to the main menu.

Step 11: Select the BEAM type for the HyperMesh beam configuration.

• From the Mesh menu, click Element Types.

• From the 1D page, click elem types. 2. For beam = select BEAM.

3. Return to the main menu.

Step 12: Create the beam.

1. From the 1D page, go to the beams panel. 2. Go to the bar2 sub-panel.

3. Click the leftmost switch and select node.

A direction node is selected later to define the beam’s section orientation. 4. Click the Node A selector to make it active.

5. Select the center node of the left nodal rigid body for Node A.

Node B is active now.

6. Select the center node of the right nodal rigid body for Node B.

7. Select any non-center node of one of the nodal rigid bodies for the direction node. Notice the beam is created.

Step 13: Restore a pre-defined view and display node IDs for ease of following

the next steps.

1. From the View menu, select User Views.

2. Click restore2 to see the nodal rigid body view. 3. On the Tool page, go to the numbers panel.

4. Leave the entity selector set to nodes.

5. Click nodes and select by id. Enter 425-427, 431 and press ENTER. 6. Display on the IDs.

7. Return to the main menu.

Step 14: Set the current component to welding.

Step 15: Select the RgdBody type for the HyperMesh rigid configuration.

2. For rigid = select RgdBody. 3. Return to the main menu.

Step 16: Create the nodal rigid body (*CONSTRAINED_NODAL_RIGID_BODY).

2. From the Ls -Dyna keyword list, point to *CONSTRAINED 3. Click on *CONSTRAINED_NODAL_RIGID_BODY 4. Set nodes 2-n to multiple nodes.

5. Select the beam’s free end for node1.

6. Select nodes 425, 426, 427 and 431 for nodes 2-n. 7. Leave active the attach nodes as set option. 8. Create the nodal rigid body.

9. Return to the main menu.

Step 17: Restore a pre-defined view and display node IDs for ease of following

the next steps.

1. From the View menu, click User Views. 2. Click restore3 to see the joint view.

3. From the Tool page, go to the numbers panel to display node IDs. 4. Leave the entity selector set to nodes.

5. Click nodes and select by id. Type 1635, 1636 and press ENTER. 6. Turn on the ids.

7. Return to the main menu.

8. From the toolbar, click the Wireframe Elements (Skin Only) icon to change to standard graphics mode.

Step 18: Activate coincident picking.

1. Press O on the keyboard to access the options panel. 2. Go to the graphics sub-panel.

3. Activate coincident picking. 4. Return to the main menu.

Step 19: Set the current component to joint.

Step 20: Create a revolute joint between two nodal rigid bodies

(*CONSTRAINED_JOINT_REVOLUTE).

The rigid bodies must share a common edge along which to define the joint. This edge, however, must not have the nodes merged together. The two rigid bodies will rotate relative to each other along the axis defined by the common edge.

1. From the Tools menu, click Create Cards.

2. From the Ls -Dyna keyword list, point to *CONSTRAINED 3. Click on *CONSTRAINED_JOINT_REVOLUTE \ 4. Set the joint type to revolute.

6. Move the mouse to node 1635 in the coincident picking display and click on it to select it for node 1 in rigid body A.

Node2 is now active.

7. Click on node 1635 again to see the coincident picking mechanism and select node 1633 for node 2 in rigid body B.

Node3 is now active.

8. Click on node 1636.

Two coincident nodes are displayed – 1636 and 1634 9. Select node 1636 for node 3 in rigid body A.

Node4 is now active.

10. Select node 1634 for node 4 in rigid body B. 11. Create the joint.

12. Return to the main menu.

Steps 21-23: Define *DEFORMABLE_TO_RIGID to set up the moving seat as

rigid until the time of impact with the block, to reduce computation time.

Step 21 Create an entity set that contains the components base_frame,

back_frame, and cover.

1. From the Setup menu, click Entity Sets. 2. For name = type set_part_seat. 3. For card image, select Part

Notice the entity selector is set to comps.

4. Select the base_frame, back_frame and cover components. 5. Create the set.

6. Return to the main menu.

Step 22: Define *DEFORMABLE_TO_RIGID to switch the deformable seat to

rigid at the beginning of the analysis.

1. From the Tools menu, click Create Cards.

2. From the Ls -Dyna keyword list, point to *DEFORMABLE_TO_RIGID. 3. Click on *DEFORMABLE_TO_RIGID.

4. For name =, type dtor.

5. For the part set ID, [PSID], specify the set_part_seat set ID.

6. For the master rigid body, [MRB], specify the back_frame component. 7. Return to the main menu.

Step 23: Create *DEFORMABLE_TO_RIGID_AUTOMATIC to switch the rigid

seat to deformable when contact between the seat and block is detected.

2. From the Ls-Dyna keyword list, point to *DEFORMABLE_TO_RIGID. 3. Click on *DEFORMABLE_TO_RIGID_AUTOMATIC.

4. For name =, type dtor_automatic.

5. For the unique set number for this automatic switch set, [SWSET], enter 1. 6. For the activation switch code [CODE] select 0.

The switch will take place at [TIME1]. 7. For [TIME1] enter 175.

The switch will not take place before this time. 8. Activate R2D_Flag in the menu area.

On export, the number of rigid parts to be switched to deformable is written to the R2D field (card 2, field 6). This number is based on the number of parts in the entity set you select next.

9. Move the scroll bar on the left side of the card image down to see [PSIDR2D]. 10. For the [PSIDR2D] field specify the set_part_seat set ID.

11. Return to the main menu.

Steps 24-28: Review the model’s data using the Content Table tool.

• From the Utility menu, click DYNA Tools, then click Content Table.

Step 24: Display only parts with a particular material (Ex: steel).

2. Select material steel and click proceed.

Notice that the GUI and the content table show only those components with material steel assigned. All other components get turned off.

3. Follow the above steps to select components using By Properties and BY thickness option.

Step 25: Display all components.

Step 26: Rename a part.

1. From the Table menu, click Editable to make the content table editable. (All columns with a white background can be edited. Ex: Part name, Part id, Thickness etc.)

2. Click on any part name field to edit it. 3. Click Yes to confirm.

4. Click the disp icon to go to the Display panel to notice the part’s new name.

Step 27: Renumber a part id.

2. Type a number that does not conflict with the existing part IDs. 3. Click Yes to confirm.

Step 28 (Optional): The exercise is complete. Save your work to a HyperMesh

file.

Section 2: Define Boundary Conditions and Loads

Exercise 2: Define Boundary Conditions and Loads for the Seat

Impact Analysis .

This exercise will help you continue to become familiar with defining LS-DYNA boundary conditions and loads using HyperMesh.

In this exercise, you will define boundary conditions and load data for an LS-DYNA analysis of a vehicle seat impacting a rigid block. The seat and block model is shown in the image below.

This exercise contains the following three tasks.

• Define gravity acting in the negative z-direction with *LOAD_BODY_Z

• Define the seat’s acceleration with *BOUNDARY_PRESCRIBED_MOTION_NODE

• Export the model to an LS -DYNA 970 formatted input file and submit it to LS-DYNA

Step 1: Make sure the LS-DYNA user profile is still loaded.

Step 2: Retrieve the HyperMesh file seat_2.hm.

Step 3: Define gravity acting in the negative z-direction with *LOAD_BODY_Z.

2. From the Ls -Dyna keyword list, point to *LOAD. 3. Click on *LOAD_BODY_Z.

4. For name =, type gravity.

5. For the load curve LCID, specify the ID of the curve named gravity curve. 6. For the load curve scale factor [SF], specify 0.001.

7. Return to the main menu.

Steps 4-7: Define the seat’s acceleration with

*BOUNDARY_PRESCRIBED_MOTION_NODE.

Step 4: Create a load collector for the acceleration loads to be created.

2. Set the collector type to load collectors. 3. For name =, type accel.

4. For creation method, select no card image. 5. Optionally select a color for the load collector. 6. Create the load collector.

7. Return to the main menu.

Step 5: Select the PrcrbAcc type for the HyperMesh acceleration

configuration.

Step 6: Create acceleration loads on nodes.

2. From the Ls -Dyna keyword list, point to *BOUNDARY

3. Click on *BOUNDARY_PRESCRIBED_MOTION_NODE (Accl) 4. With the nodes selector active, select nodes >> by sets. 5. Select the pre-defined entity set accel_nodes.

6. For magnitude, specify 0.001.

This is the scale factor for the pre-defined curve to be specified in the next step for the acceleration loads. It will define the seat’s acceleration as a function of time.

7. For the direction selector, select x-axis.

This is the x-translational degree of freedom, EQ. 1. 8. For the magnitude% =, specify 1.0E+7.

This is the scale factor for the graphical representation of the acceleration loads. It does not affect the actual acceleration value.

9. Create the acceleration loads. 10. Return to the main menu.

Step 7: Edit all of the acceleration loads simultaneously to specify the

pre-defined xy curve named "acceleration curve" for them.

1. From the Setup menu, click Card Editor. 2. Set the entity selector to loads.

3. With the loads selector active, select loads >> by collector. 4. Select the load collector accel.

5. For config =, select accels.

6. For type =, leave it set to PrcrbAcc. 7. Edit the acceleration loads.

8. For load curve [LCID], specify the ID of the curve named acceleration curve. 9. Return to the Card Editor panel.

10. Return to the main menu.

Step 8: Export the model to an LS-DYNA 970 formatted input file.

Step 9 (Optional): Submit the LS-DYNA input file to LS-DYNA 970.

3. Load the file seat_complete.key. 4. Click OK to start the analysis.

Step 10 (Optional): View the results in HyperView.

Step 11 (Optional): The exercise is complete. Save your work to a HyperMesh

file.

Model Importing, Airbags, Exporting Displayed, and

Contacts using DYNA - HM-4615

In this tutorial, you will learn how to:

• Define *AIRBAG_WANG_NEFSKE for the airbag mesh geometry

• Define an initial velocity of 3 mm/ms in the negative x-direction for the head with *INITIAL_VELOCITY_GENERATION

• Define a contact between the airbag and head with *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE

• Define *CONTACT_AIRBAG_SINGLE_SURFACE for the airbag

• Define a contact between the plate and the airbag with *CONTACT_NODES_TO_SURFACE

Import DYNA model

Warning and Error Messages

On import of a DYNA model, any HyperMesh warning and error messages are written to a file named dynakey.msg or dynaseq.msg, depending on the feinput translator used. This file is created in the same folder from which HyperMesh is started.

Unsupported Cards

On import, few DYNA cards not supported by HyperMesh are written to unsupp_cards panel. This panel can be accessed from Setup menu by clicking on Control Cards. The unsupported cards are exported with the remaining model.

Care should be taken if an unsupported card points to an entity in HyperMesh. An example of this is an unsupported material referenced by a *PART. HyperMesh stores unsupported cards as text and does not consider pointers.

LSTC Dummy Files

You can read LSTC Hybrid III dummy files into HyperMesh by first converting the tree file to FTSS/ARUP tree file format.

Include Files

HyperMesh supports *INCLUDE. In the files panel, import sub-panel is the option to read include

files, skip include files and preserve include files. When include files are read, HyperMesh

maintains the IDs of non-existing entities and does not use these IDs for new entities.

Export Displayed

In the files panel, export sub-panel, you can toggle the all option to the displayed option to export only displayed nodes and elements. Only model data associated to the displayed nodes and elements are exported. This model data includes materials and their associated curves, properties, portions of contacts, and output requests.

Create and Review Contacts

The table below describes how all slave and master set types are created and specified in contacts.

Slave and master set type

DYNA card Panel used to create card Equivalent type in interfaces panel, add sub-panel EQ. 0: set segment id *SET_SEGMENT set_segment (contactsurfs) or … csurfs

interfaces, add

sub-panel

entity

entity sets or… sets

EQ. 1: shell element set id

*SET_SHELL_Option

interfaces, add

sub-panel

entity

entity sets or… sets

EQ. 2: part set id

*SET_PART_LIST

interfaces, add

sub-panel

comps

EQ. 3: part id *PART collectors comps

* EQ. 4: node set id

*SET_NODE_Option entity sets or… sets

interfaces, add

sub-panel

entity

* EQ. 5: include all

interfaces, add

sub-panel

all

* EQ. 6: part set id for exempted parts

*SET_PART_LIST interfaces, add

sub-panel and then card

image sub-panel

sets

* For slave surface only

Add sub-panel

While the interfaces panel, add sub-panel has several master and slave types - comps, sets,

entity, etc. - to choose from in order to specify the DYNA master or slave set for a *CONTACT, only

the valid master and slave types are selectable for the particular contact you are creating.

When the master or slave type is set to comps and only one component is selected, the DYNA type is 3, part ID, and *PART is created. When multiple components are selected, the DYNA type is 2, part set ID, and *SET_PART_LIST is created.

When the master or slave type is set to sets, only those sets valid for the particular contact you are creating are selectable. For example, for *CONTACT_NODES_TO_SURFACE, only a list of node

Review Contacts

You can review contacts with the review button in the interfaces panel, add sub-panel.

Exercise: Define Airbag, Velocity, and Contacts for the Airbag

Analysis.

This exercise will help you become familiar with defining LS-DYNA airbags using HyperMesh. It will also help you continue to learn how to define LS-DYNA loads and contacts using HyperMesh. In this exercise, you will define an airbag, velocity, and contacts for an LS -DYNA analysis of a head impacting an inflating airbag. The head and airbag model is shown in the image below.

Head and airbag model

Step 1: Load the LS-DYNA user profile.

Step 2: Import the LS-DYNA input file, airbag_start.key.

Notice the FE radio button is active and next to the switch is DYNA KEY. This means the DYNA

KEY import translator is selected. It was automatically selected when you loaded the Ls -Dyna

user profile.

2. Import… the file airbag_start.key. 3. Return to the main menu.

Define *AIRBAG_WANG_NEFSKE for the airbag mesh geometry.

Step 3: Create a set of parts, *SET_PART_LIST, containing the AirbagFront

and AirbagRear components.

1. On the Setup menu, click Entity Sets. 2. For name =, type airbag_set. 3. For card image, select Part.

4. Click on Comps and select the components AirbagFront and AirbagRear. 5. Create the set.

6. Return to the main menu.

Step 4: Define the airbag (*AIRBAG_WANG_NEFSKE).

2. From the Ls -Dyna keyword list, point to *AIRBAG 3. Click on *AIRBAG_WANG_NEFSKE.

4. For name =, type airbag.

5. With the set selector active, select the entity set airbag_set. The parts in this set define the airbag’s geometry.

6. Click update.

7. Edit the control volume.

8. Enter the following data in the card image.

Value Field Parameter description

1023.0 _{CV Heat capacity at constant volume} 1320.0 _{CP Heat capacity at constant pressure} 780.0 T Temperature of input gas

curve id 1 _{LCMT Load curve specifying input mass flow rate}

1.0 C23 Vent orifice coefficient

curve id 2 _{LCA23 Load curve defining vent orifice area as a function of}

pressure

1.0 _{CP23 Orifice coefficient for leakage} 1.0E-4 PE Ambient pressure