ANSYS Explicit Dynamics 120 Workshop 02

WS 2-1ANSYS, Inc. Proprietary

© 2009 ANSYS, Inc. All rights reserved.February 27, 2009

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Workshop 2

Simulate the Crushing of an Empty Soda Can

ANSYS Explicit Dynamics

Workshop 2. Simulate the Crushing of an Empty Soda Can



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Training ManualWorkshop Goal and Procedure

Goal:

Crush an aluminum beverage can and allow it to “springback”

Procedure:

Create an Explicit Dynamics (ANSYS) Analysis System Project

Select the units system and define the material properties

Import, modify, and mesh the soda can geometry

Define analysis settings, boundary conditions, and external loads

Initiate the solution (AUTODYN - STR) and review the results




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Training ManualStep 1 – Create the Project Schematic

Start ANSYS Workbench and follow the sequenced steps using the

abbreviations shown below:

– DC = Double Click with Left Mouse Button

– SC = Single Click with Left Mouse Button

– RMB = Right Mouse Button Selection

– D&D = Drag and Drop = Hold Left Mouse Button down on item while

dragging it to new location and then release it (i.e., Copy or Move)

DC

1. Create an ANSYS Explicit Dynamics Analysis System Project




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Training ManualStep 2 – Specify the Project Units

2.a Select MKS for the Project Unitsfrom the Units List provided

2.b Request that Native Applications in Workbench have their values be

Displayed in the Project Units

2.c Check those unit systems to

Suppress from appearing in the

Units List

Note:

Engineering Data is nativein Workbench,

but Mechanical is NOT at this

time (but will be

in the future).




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Training ManualStep 3 – Define Engineering Data Material

3.a Edit the Engineering Data cell to add a

material to the default library.

3.b Select the last slot under Engineering Data to define a new material model.

SC

3.c Enter material

model name:

“My_Aluminum”

Note: An existing material model in the Explicit Materials library could have been selected, but there are restrictions on element types that can be used with certain material models, which will be discussed later.

DC




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Training Manual

DCDC

DC

Step 3 – Define Engineering Data Material ...

SC3.e Add the following Physical Properties to

the material definition:

– Density

– Isotropic Elasticity

– Bilinear Isotropic Hardening

3.d Make sure the new

material is active in

order to define its

properties




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Training ManualStep 3 – Define Engineering Data Material ...

3.f Enter the following values:

Density = 2710 kg m^-3

Young’s Modulus = 7e10 Pa

Poisson’s Ratio = 0.30

Yield Strength = 2.9e8 Pa

Tangent Modulus = 0.0 Pa

Since the material is sufficiently

defined, the blue question

marks and yellow fields are no

longer present in the data table.

Note: The resulting stress-strain

curve is elastic – perfectly

plastic. No strain hardening can

develop.




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Training ManualStep 3 – Define Engineering Data Material ...

3.g Return to the Project Schematic

3.h Save the Project by selecting the

“Save As ...” icon and Browse to the

directory indicated by your instructor.

Use the name “empty_soda_can” for

the Project name.

Note: Saving the

Project saves all of

the important files.

The Project may

also be Archived, in

which all of the

supporting files are

compressed and

saved in one file.




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Training ManualStep 4 – Import and Modify the Geometry

4.c Workbench has now identified

the geometry file (note green

checkmark in Geometry cell). It

is now OK to Double Click on

“Geometry”, as the new default

action is to Edit the geometry.

Default actions are shown in

bold type after RMB selects.

RMBSC

4.a Import the geometry by the procedure shown.

Do NOT Double Click on the “Geometry” cell ...

4.b Browse to the DesignModeler

11.0 SP1 geometry file named:

“soda_can_filled_110.agdb”

RMBSC




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Training ManualStep 4 – Import and Modify the Geometry ...

4.d Suppress the solid “Soda”

and the surface body “Hole”.

RMB

SC

4.e Generate the changes in the

geometry. Although additional

modifications could be made,

but none are needed.

4.f Save the entire

Project via the DM

“Save” icon.




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Training ManualStep 5 – Edit the Model in Mechanical

5.a Edit the model in Workbench Mechanical.

Since Edit is the default action, double-clicking on

the Model cell is also acceptable here.

RMB SC

5.b Select the MKS Units system

– Recall that Mechanical is not native in Workbench, so

the Units here may not match the Project Units

Note: Although the unit system used for data entry

and post-processing is the MKS system, the actual

unit system used by the AUTODYN solver is the

mm-mg-ms system, because it provides higher

accuracy. This will be shown later when the

Analysis Settings are discussed.




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Training ManualStep 5 – Edit the Model in Mechanical ...

Rigid Steel Punch

(moved downwards)

Flexible Aluminum

Soda Can (crushed)

Rigid Steel Die (fixed)

5.c Define the Aluminum Can properties:

– Stiffness Behavior = Flexible

– Thickness = 0.00025 meters

– Material Assignment = My_Aluminum

5.d Define the Punch and Die properties:

– Stiffness Behavior = Rigid

– Material Assignment = Structural Steel




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Training ManualStep 5 – Edit the Model in Mechanical ...

5.e Review the Contact specifications

Keep contact

definition defaults

5.f Save the Project

Note: There is no Saveicon in Mechanical




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Training ManualStep 6 – Set Sizing Controls and Mesh Model

6.d Orient the model to select the 8 edges

that define the can circumferences (with

the Left Mouse Button). Use the Ctrl key

for multiple selections, as needed.

6.a Select the Mesh branch

6.b Specify the Mesh Details:

– Physics Preference = Explicit

– Element Size = 0.010 meters

6.c Choose the Edge selection filter

RMB (anywhere)

6.e With the 8 edges still highlighted,

Insert (RMB anywhere on graphics

screen) an Edge Sizing

SCSC




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Training ManualStep 6 – Set Sizing Controls and Mesh Model ...

6.f Specify the Edge Sizing Details:

– Type = Number of Divisions

– Number of Divisions = 36

– Behavior = Hard

6.g Generate the Mesh (RMB on either

Mesh branch or Edge Sizing branch)

RMB

SC

Mesh view




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Training ManualStep 7 – Define the Analysis Settings

7.a Specify the Analysis Settings:

– End Time = 6.0e-4 seconds

– Automatic Mass Scaling = Yes

– Minimum CFL Time Step = 1.0e-7 sec

SC

7.b Set the Solve Units = mm, mg, ms

Note:

The mm, mg, ms unit system is the

most accurate in most simulations, so

it is the only one currently available.

Although more solver unit systems

will be available in the future, any unit

system in the drop-down list may be

used to enter data and/or display the

results.




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Training ManualStep 7 – Define the Analysis Settings ...

7.c Keep the remaining defaults

Note:

There are multiple ways to

control the erosion of an

element. In this case, the

element will only fail when

the geometric strain reaches

150%.

7.d Use the default number of

data sets to save during the

solution. Depending on the

analysis, this number may

need to be increased, but

that requires additional disk

space, so be judicious here.




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Training ManualStep 8 – Apply BCs and External Loads

8.a Fix the Steel Die (base):

– Select the Body filter

– Insert a Fixed Support under Explicit Dynamics

– Select the steel die

– Apply the selection

RMB

SC

SC




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Training ManualStep 8 – Apply BCs and External Loads ...

8.b Displace the Steel Punch

– Insert a Displacement under Explicit Dynamics

– Select the steel die

– Apply the selection

RMB

SC

SC




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Training ManualStep 8 – Apply BCs and External Loads ...

Note: The punch speed and abrupt change in direction are unrealistic,

but sufficient for demonstration purposes. Normally, the movement

would be prescribed according to a SINE wave function.

8.c Specify the vertical (Y) displacement

to be a Tabular load and set both the X

and Z displacements to be zero.

8.d Ramp the Y displacement as follows:

Time = 0.0 sec Y = 0.0 meters

Time = 5e-4 sec Y = -0.060 meters

Time = 6e-4 sec Y = -0.030 meters




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Training ManualStep 9 – Insert Result Items to Postprocess

9.a Insert a Total Deformation plot

request under the

Solution branch.

9.b Insert an Equivalent (von-Mises) Stressplot request under

the Solution branch.

The rigid bodies (i.e.,

the punch and die)

will not show stress.

RMB

RMB

SCSC

SC SC

SC

SC




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Training ManualStep 9 – Insert Result Items to Postprocess ...

9.c Insert an Equivalent Plastic Strainplot request under the Solutionbranch.RMB

SC

SC

SCNote:

Even though a single time point (at the end of the run) is specified,

the complete set of results can be viewed, including animations.

Recall that the default output controls (20 equally spaced time

points) was retained under the Analysis Settings branch.

9.d Save the

Project again.




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Training ManualStep 10 – Run the AUTODYN Simulation

10.a Select Solver Output under Solution Information and Solve the simulation.

The Solver Output shows the run statistics, including the estimated

clock time to completion. Any errors or warnings are also noted.

Termination due to “wrapup time reached” is expected here.

SC




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Training ManualStep 10 – Run the AUTODYN Simulation ...

10.b Select Energy Summary under Solution Information to review the global statistics.

Note the abrupt changes in kinetic energy

due to the unrealistic loading scenario ...

TIME = 5.0e-4 seconds occurs

around 3200 cycles into run

Constant velocity after

starting from rest




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Training ManualStep 11 – Review the Results

11.a Select Total Deformation and Show the Elements under True Scale. The maximum deformation (-0.060 m) exceeds the punch

value due to the momentum involved (i.e., an excessive punch

speed was used to reduce the required computer run time).

SC




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Training ManualStep 11 – Review the Results ...

11.b Animate the results by setting the controls as shown below and

then pressing the Animation button. For transient dynamics, the

default Distributed mode is inadequate, as it linearly interpolates

between saved results. The Result Sets mode is optimal, as it

uses the actual saved data. To review a static result, just click on

the desired Time or Value from the Tabular Data and use the RMB

to pick Retrieve This Result. The given state will then be shown.

RMB

Pick these 2 first

Then pick thisPick this to

save the

animation

To retrieve a given result ...




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11.c Repeat the procedure, if

desired, for the von-Mises

equivalent stress results.

Note:

No stress can develop in a

rigid body. The punch and

die are each condensed out

to a mass at their respective

centers of gravity with six

DOFs active.

Contact is based on

the exterior surface,

so a six DOF body can

have a complicated

contact surface.

SC




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11.d Repeat the procedure one last time for the

equivalent plastic strain results.

11.e. Hide the Punch and Die for a better view of the

results. Per the Analysis Settings, erosion does

not occur until the geometric strain is 1.50

SC

SC

RMB




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Training ManualStep 12 – Review the Output Files

12.a Pick Files under the View menu to access the Project files

12.b Select Open Containing Folder via the RMB option

for the AUTODYN print file (admodel.prt).

RMB




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Training ManualStep 12 – Review the Output Files ...

12.c Double click on the file admodel.prt

12.d As noted earlier, the solver

units system was mm-mg-ms in

order to maximize the accuracy.

After the Simulation is done, the

results are converted back into

the current Mechanical units

system.




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12.e The AUTODYN print

file also contains the

Material Summaryinformation and run

statistics.

The Energy and

Momentum are shown

on both a material

basis and a Part basis

(shown here).




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12.f The Energy and Momentum Balance, Mass Scaling, and Run Timesare also included in the admodel.prt file.

12.g No mass was

added to the

model, since

the time steps

were all above

the Minimum

CFL Time Step

of 1.0e-7 sec

set in Step 7.a

under Analysis

Settings




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12.h Close the admodel.prt file and review the setup.log file in the same

directory (F:\exp_dyn\soda_can\empty_soda_can_files\dp0\SYS\MECH).

12.i The setup.log file contains

the information pertaining to

the transfer of data from the

Explicit Dynamics (ANSYS)

Analysis System to the

AUTODYN Cycle Zero file,

which is then run by the

AUTODYN solver.

12.j Close the file and return to

the Mechanical window (i.e.,

view the model itself again).




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Training ManualStep 13 – Generate a Report

13.a Click on the Solution branch in the Project tree and then click on

the Report Preview tab at the bottom of graphics window. ANSYS

does the rest! It will now automatically generate a report by going

through the entire tree and summarizing the model and the results.




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Training ManualStep 13 – Generate a Report ...

13.b The model properties

are summarized,

including volume, mass,

centroid, and moment of

inertia properties.

13.c Loading information is

also shown in clear table

format.




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13.d Even the energy plots are conveniently assembled into the report.




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13.e The results data is shown.

13.f Finally, SAVE the model

and exit ANSYS.

ANSYS Explicit Dynamics 120 Workshop 02

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