General (Basic) Contact Family Automatic Contact Family Rigid Contact Family 7 7
Tied Contact Family Tiebreak Contact Family
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Boundary Condition Apply boundary condition in the Constraints
module, it includes fixed condition for immovable parts like floor or wall.
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Boundary Condition Initial velocity is most commonly used input
for a impact/drop test.
Initial Velocities are applied on node
components.
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Solution- Ls Dyna Solver The termination time is the actual time for
which the simulation of physical process is run (often in ms).
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Output request and frequency Specify how often results for the entire
model are written.
can output a series of LS-DYNA ASCII output
files that contain specialized information
energy
forces
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GLSTAT BNDOUT
- Global statistics data - Boundary condition forces and
RWFORC DEFORC MATSUM NCFORC RCFORC DEFGEO SPCFORC
-
Rigid wall forces Discrete element forces Material energies summary Nodal interface forces Resultant interface forces Deformed geometry data Single point constraint reaction
SWFORC RBDOUT GCEOUT SLEOUT JNTFORC NODOUT
-
Nodal constraint reaction forces Rigid body data Geometry contact entities Sliding interface energies data Joint force data Node data
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Post Processing POST1, the ANSYS General Postprocessor Animation Deformation, Stresses
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Post Processing : Time History POST26 Time History Postprocessor Plot time-history curves, plot acceleration,
velocity, displacement vs time .
Access LS Dyna Ascii output files.
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Example Plate impacting Plate
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Definition A Shell Elements drop and rebounds from a
elastic plate.
Plate measure 40*40*1 mm3 (16 elements) Dropped shell has 10mm side length and 2
mm thickness.
Drop height is 10mm Element formulation is Belutschko-Tsay Define a surface to surface contact with 2
way detection.
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Define the elastic plate as Master 5/3/12and
impacting shell as slave.
Set-Up For model setup we use various option in
the preprocessor tab.
Create 2 areas with required dimension as
shown below (Preprocessor-Modelingcreate-). Transform drop shell to required drop
height.
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Meshing Define Element Type 163 (Preprocessor-Element type-add/edit/delete-)
Part should be defined using right
combination of material , real contact , element type. Before meshing this has set and can be confirmed at status bar.
Part
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1 Status2 Bar
Material 1 1
Element Type 1 1
Real constant 1 2
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Meshing cont… Define Real Constant to assign section
properties or thicknesses. For each thickness there should be one real constant. (Preprocessor-Real Constants)
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Meshing Cont…Material Properties Define material properties for various parts
using option shown below. (PreprocessorMaterial Props-Material Models)
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Creating Parts Assign the correct material, section
properties and element type to create parts.
For LS-Dyna to recognize a part, its should
be a group of elements that have the same combination of element type, real constant set, and material reference numbers
Repeat this to all area/components
(Preprocessor-Meshing – Mesh Attributes)
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Revisiting Meshing Set line seeding or element size.
(Preprocessor-Meshing-Mesh tool-Set)
Mesh Volume ,Areas and lines to generate
solid, shell or beam elements. Refer images below to access the meshing
tool.
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Creating Components We need to create node and elements
components for
Adding Constrains to a group of nodes Defining Velocity to a part (part nodes need to
be grouped) Defining a master surface and node surface
(associated nodes of surface need to be grouped) To request output for required parts/region of
interest. 22 22
In this model create node and element 5/3/12
component for both the areas you could name
Adding Constrains to Model The plate is fixed at its boundaries
(Preprocessor-LS-DYNA-Constraints-On Nodes)
Create a node component or select the
desired nodes to apply the constrains.
Refer images below to access the menu
options to add constrain.
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Defining contacts In this model we will create a Automatic
Surface to Surface Contact. Choose the moving plate as contact surface and fixed plate as target surface. (Preprocessor-LSDYNA-Contact-DefineContact)
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Initial Velocity The moving plate has initial velocity of
100,000 mm/s in vertical direction.
Initial velocity can be applied using option
under LS-Dyna Option tab as show below. (Preprocessor-LS-DYNA-Initial Velocityw/Nodal Rotate)
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Solution Setting As per problem definition end time is
0.0002 sec, remember that most of impact problem occur over a time of ms.
We now use option in the solution tab
(Solution – Time Controls – Solution Time)
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Output Controls In output controls we Request for both Ansys and LS-Dyna Result
formats
Set the frequency at which result files are
written
Request for Special Ascii files which has
information on system energies, Nodal and You could request for 10 Elemental results. Ascii files at a time the most frequent used are Global statistics data Boundary condition forces and energy Material energies summary Geometry contact entities Node data
Select the components for which Time-History
results has to be written. 27 27
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Solution and Results Click on the Solve option in run the
simulation (Solution – Solve)
As Discussed before this example Post
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processing option are test.avi General Post Proc Time History Post Pro 5/3/12 Attached is the animation of the solved
Time- History Post Processing TimeHist Postpro > Variable Viewer > File
> Open > Explicit Dynamics Results (*.his) > Jobname.his
