Engineering Solutions

Pre-Simulation (Seat Deformer)

Pre-Simulation (Seat Deformer)

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Pre-Simulation (Seat Deformer)

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This tool can be accessed by clicking Safety > Pre-Simulation(Seat Deformer) from the menu bar.  

When a dummy is positioned to its H-Point location on a seat, intersections between the dummy and seat foam parts generally occurs.

Use the Seat Deformer tool to export an input deck, for the appropriate solver, in order to simulate the deformation of the seat under the dummy. The simulation result files can be imported to update the initial FE model and remove the intersections and penetrations between the dummy and the seat.

This tool is only available in the LS-DYNA and Altair Radioss user profiles.              

hmtoggle_plus1greySeat Deformer Process Description

seat_deformer

The image above shows the initial model with the dummy positioned at its correct H-Point location, and shows intersections with the seat    

The selected dummy components move following the direction that you move them in until no penetrations between the dummy and seat components are detected. The dummy components are rigidified. A contact between the seat and dummy is automatically created with user defined parameters as well as a fix boundary condition on the selected fixed nodes of the seat. Finally, an imposed displacement is applied on the dummy components to bring them back to the initial position.  

seat_deformer_02

The pre-simulation load case is ready and the dedicated input deck is exported to the user specified location, as shown below. When the solver analysis is done, you can import the dedicated solver output file to update the initial model with the deformed geometry and initial stresses of the seat parts.    

seat_deformer_03
hmtoggle_plus1greyPreSimulation Tool Dialog

LS-DYNA user profile

presimulation_tool_lsdyna

Option

Description

Unit System

Selecting a unit system will automatically set up the default simulation parameters to the correct unit. In any case, you can still modify these values manually.    

Dummy

Dummy components that are selected in contact with the seat will be exported for the pre-simulation. The selection can be done via:    

•Components
•Mechanism: Opens a dialog to select a complete dummy
•Assemblies
•Set: Opens a dialog to select a set of type *SET_PART_LIST

 

Seat

Select the seat components that will be exported for the pre-simulation. The selection can be done via:  

•Components
•Mechanism: Opens a dialog to select a mechanism defining the seat. Only the bodies that are defined by components or sets of components will be taken into account.  
•Assemblies
•Set: Opens a dialog to select a set of type *SET_PART_LIST

Fixed Nodes of Seat

Select the nodes that will be fixed during the simulation. The selection can be done via:

•Nodes
•Set: Opens a dialog to select a set of type *SET_NODE_LIST

Dummy Displacement Direction

Defines the vector in which the dummy components will be moved to the starting simulation position when penetrations with the seat are no longer detected.  

Export File

Defines the pre-simulation deck name and location

Dummy Velocity

Defines the imposed velocity value applied on the dummy parts during the simulation. Default value = 0.1mm/ms

Time Step

Defines the control time step value. Default value = 0.001ms

Scale Materials Density

Scale factor to scale the material density values in order to increase the critical time step of the model. Default value = 10  

Dummy Displacement Step

Displacement increment used to move the selected dummy components along the prescribed vector. After each increment, the penetration check between the dummy and seat will be performed and the dummy motion will be stopped when penetrations are no longer detected. Default value = 10    

Soft

Defines the Soft parameter value in the generated contact between the dummy and seat. Default value = 2    

Friction

Defines the FS parameter value in the generated contact between the dummy and seat. Default value = 0.0    

Imposed Contact Thickness

Defines the value of parameters SST, MST and SLDTHK in the generated contact between the dummy and seat. Default value = 0.0

Contact Stiffness Scale Factor

Defines the value of parameter SFS in the generated contact between the dummy and seat. Default value = 0.0

Import *INITIAL_STRESS_SOLID

If this checkbox is activated, initial stresses for solid elements will be imported from the dynain file. This option is activated by default.  

Import *INITIAL_STRESS_SHELL

If this checkbox is activated, initial stresses for shell elements will be imported from the dynain file. This option is deactivated by default.      

Import *INITIAL_STRESS_BEAM

If this checkbox is activated, initial stresses for beam elements will be imported from the dynain file. This option is deactivated by default.    

Export

Starts the export process of the pre-simulation deck at the specified location.

Import dynain File

Allows the LS-DYNA simulation to update the initial model.  

Close

Closes the dialog.

Altair Radioss user profile

presimulation_tool_radioss

Option

Description

Unit System

Selecting a unit system will automatically set up the default simulation parameters to the correct unit. In any case, you can still modify these values manually.    

Dummy

Dummy components that are selected in contact with the seat will be exported for the pre-simulation. The selection can be done via:    

•Components
•Mechanism: Opens a dialog to select a complete dummy
•Assemblies
•Set: Opens a dialog to select a set of type /GRPART

 

Seat

Select the seat components that will be exported for the pre-simulation. The selection can be done via:  

•Components
•Mechanism: Opens a dialog to select a mechanism defining the seat. Only the bodies that are defined by components or sets of components will be taken into account.  
•Assemblies
•Set: Opens a dialog to select a set of type /GRPART

Fixed Nodes of Seat

Select the nodes that will be fixed during the simulation. The selection can be done via:

•Nodes
•Set: Opens a dialog to select a set of type /GRNOD

Dummy Displacement Direction

Defines the vector in which the dummy components will be moved to the starting simulation position when penetrations with the seat are no longer detected.  

Export File

Defines the pre-simulation deck name and location

Generate XREF for initial stresses

Enables the creation of /XREF cards for the seat components that are compatible with this Altair Radioss feature in terms of material type and element formulation. This checkbox is activated by default.    

Dummy Velocity

Defines the imposed velocity value applied on the dummy parts during the simulation. Default value = 0.1mm/ms

Time Step

Defines the control time step value. Default value = 0.001ms

Scale Materials Density

Scale factor to scale the material density values in order to increase the critical time step of the model. Default value = 10  

Dummy Displacement Step

Displacement increment used to move the selected dummy components along the prescribed vector. After each increment, the penetration check between the dummy and seat will be performed and the dummy motion will be stopped when penetrations are no longer detected. Default value = 10    

Friction

Defines the friction value in the generated contact between dummy and seat. Default value = 0.0

Stmin

Defines the minimum contact stiffness in the generated contact between dummy and seat. Default value = 1.0kN/mm

Gap_Min

Defines the minimum gap in the generated contact between dummy and seat. Default value = 0.5

IGAP

Defines the IGAP value for the generated contact between dummy and seat. Default value = 2

Export

Starts the export process of the pre-simulation deck at the specified location.

Import h3d File

Allows the Altair Radioss simulation to update the initial model.    

Close

Closes the dialog.

 

 

 

See Also:

Safety Menu

Crash Application