Ansys Autodyn 120 Workshop 06

Workshop 6 Bird Strike

ANSYS AUTODYN

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February 27, 2009 Inventory #002665

Workshop 6. Bird Strike

Workshop Goal and Procedure

Training Manual

Goal: Model a bird strike on an aircraft wing

Procedure: Set up the problem in Explicit Dynamics (ANSYS) Transfer the setup to AUTODYN Convert the Bird Part to use SPH nodes Run the analysis in AUTODYN

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Workshop 6. Bird Strike

Step 1 – Start Workbench

Training Manual

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)

Throughout these Workshops, the procedures shown are not always the only way to accomplish the desired tasks, so feel free to investigate other methods via the documentation when outside of this course • The workshops consistently use RMB in the Outline tree to access options whenever possible • Often these options can also be accessed through the “Context” Toolbar • Sometimes these options can also be accessed using RMB in the View area ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.

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Step 2 – Initiate an Explicit Dynamics (ANSYS) Project

Training Manual

2.a Create an Explicit Dynamics (ANSYS) Project SC

DC

2.b Select MKS for the Project Units and request Native Applications in Workbench have their values Displayed in the Project Units ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.

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Workshop 6. Bird Strike

Step 3 – Define Engineering Data Material DC

Training Manual

3.a Edit the Engineering Data cell to select pre-defined material models from one of the pre-defined material libraries 3.b Select the Explicit Materials library. Materials in this library have physical property data defined for explicit analyses

SC

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Workshop 6. Bird Strike

Step 3 – Define Engineering Data Material ...

Training Manual

3.c Select the “+” sign to the right of AL5083H116 to add it to the Engineering Data library.

3.d Likewise, select the “+” sign to the right of WATER2. Note the symbol of a book that appears indicating success

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SC

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Step 3 – Define Engineering Data Material ... 3.e Go to the Engineering Data cell and note the added materials

Training Manual

SC

3.f Return to the Project Schematic 3.g Save the Project by selecting the “Save As” icon and Browse to the directory indicated by your instructor. Enter “bird_strike” for the Project name

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Workshop 6. Bird Strike

Step 3 – Define Engineering Data Material ...

Training Manual

3.h Temporary fix Return to Engineering Data and enter “0” for the Shear Modulus for WATER2. (This is an error that will be fixed in the next release)

0

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Workshop 6. Bird Strike

Step 4 – Import the Geometry

Training Manual

4.a Import the geometry database bird_strike.agdb as shown below

RMB

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SC

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Step 5 – Edit the Model in Mechanical

Training Manual

5.a Edit the model in Workbench Mechanical.

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

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Step 5 – Edit the Model in Mechanical ...

Training Manual

5.c Assign a thickness of “0.005” meters and the material AL5083H116 to Stiffener_1, Stiffener_2, Stiffener_3 and Stiffener_4 5.d Assign a thickness of “0.003” meters and the material AL5083H116 to Skin 5.e Assign the material WATER2 to Bird

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Workshop 6. Bird Strike

Step 5 – Edit the Model in Mechanical ...

Training Manual

5.f Notice the automatically defined Body Interaction. This allows a frictionless sliding interaction between all bodies

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Workshop 6. Bird Strike

Step 6 – Generate the Default Mesh

Training Manual

6.a Generate the default mesh Quality of the Bird mesh is not important as it will only be used to create a region of SPH nodes in AUTODYN

RMB

Default mesh is reasonable, but not uniform

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Workshop 6. Bird Strike

Step 7 – Change the Mesh Method RMB

Training Manual

SC

RMB

SC

7.a Insert a Meshing Method 7.b Select all bodies (RMB in the view area)

+ SC

7.c Deselect the Bird body ( + SC on body) 7.d Select Apply ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.

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Step 7 – Change the Mesh Method …

Training Manual

7.e Select Uniform Quad for the Method 7.f Enter “0.025” m for the Element Size 7.g Enter “0.025” m for the Defeaturing Tolerance 7.h Generate the mesh

RMB SC

The mesh is now uniform ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.

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Workshop 6. Bird Strike

Step 8 – Define the Initial Conditions

Training Manual

8.a Apply an Initial Velocity Condition to the Bird as shown.

RMB

SC

SC

Select the Bird body

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Note: If the Body selection filter is not automatically activated for the initial velocity condition, select it manually.

February 27, 2009 Inventory #002665

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Step 8 – Define the Initial Conditions ...

Training Manual

8.b Choose Define by Components: X = 250.0 m/s

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Step 9 – Define the Analysis Settings

Training Manual

9.a Select Analysis Settings in the tree

SC

9.b Set the End Time to 5.0e-3 seconds in the Details View 9.c Keep the remaining default settings

9.d Save the model on the Workbench Project page At this point the project has been set up a much as is possible in Explicit Dynamics (ANSYS). It will now be transferred into AUTODYN to complete the setup for the SPH solver and run the analysis ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.

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Workshop 6. Bird Strike

Step 10 – Create (Link to) an AUTODYN Project 10.a On the Workbench Project page, under Component Systems, drag and drop the AUTODYN component onto the Setup cell for the Explicit Dynamics (ANSYS) project. This creates an AUTODYN project who’s setup is linked to the Explicit Dynamics Project

D&D

RMB

SC

10.b Open the AUTODYN project, importing the model set up in the Explicit Dynamics project ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.

Training Manual

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Step 11 – Generate an SPH Part for the Bird

Training Manual

11.c Enter “Bird_SPH” for the Part Name 11.d Select the SPH Solver

11.a Select Parts On Navigation Bar

11.e Accept the data

11.b Select New in the dialog panel ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.

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Step 12 – Create an SPH Object from the Bird Part

Training Manual

12.a Select Geometry (Zoning) 12.b Under Import Objects, select Part 12.c Select the Bird Part to convert to an object 12.d Name the Object “SPH_Bird” 12.e Accept the data

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Step 13 – Delete the (Lagrange) Bird Part

Training Manual

Now that the new SPH object has been created, the Bird Part (created in Explicit Dynamics) is no longer needed, so delete it 13.a Select Delete 13.b Select the Bird Part 13.c Accept the data New SPH Object

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Workshop 6. Bird Strike

Step 14 – Pack SPH_Bird Object with SPH Nodes

Training Manual

14.e Select Initial Condition Set 3

14.g Enter 15.0 mm for the Particle (Water and 250 m/s) Size 14.d Check Fill 14.h Accept the with Initial data 14.f Select next Condition Set

14.a Select Pack (Fill) 14.b Select the SPH_Bird object 14.c Select Pack Selected Object(s)

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Step 15 – Load a Plot Settings File

Training Manual

15.a Load the plot settings file “bird_strike_2.set” to obtain the following view

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Workshop 6. Bird Strike

Step 16 – Set up the Bird / Wing Interaction

Training Manual

16.a Select Interaction on the Navigation Bar 16.b Select External Gap (this must be used for Lagrange/SPH interactions) 16.c Enter a Gap size of “1.5” mm 16.d Select Check A message will tell you that the input parameters are OK

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Workshop 6. Bird Strike

Step 17 – Run the Analysis

Training Manual

The calculation takes approximately 40 minutes to run to completion (about 7500 cycles)

17.a Save the project on the Workbench Project Page 17.b Select Run to start the solve 17.c Once the calculation is running, Select Stop at any time to stop the calculation (you can then press Run again to continue the calculation)

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