Ansys Autodyn 120 Workshop 06

Bird Strike

Training Manual

Workshop Goal and Procedure

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

Training Manual

Step 1 – Start Workbench

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

Training Manual

2.a Create an Explicit Dynamics (ANSYS) Project

2.b Select MKS for the Project Units and request Native Applications

Step 2 – Initiate an Explicit Dynamics (ANSYS) Project

DC

Training Manual

Step 3 – Define Engineering Data Material

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

DC

Training Manual

Step 3 – Define Engineering Data Material ...

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

Training Manual

Step 3 – Define Engineering Data Material ...

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

SC

3.e Go to the

Engineering Data

cell and note the added materials

Training Manual

Step 3 – Define Engineering Data Material ...

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)

Training Manual

Step 4 – Import the Geometry

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

Training Manual

Step 5 – Edit the Model in Mechanical

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

Training Manual

Step 5 – Edit the Model in Mechanical ...

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

Training Manual

Step 5 – Edit the Model in Mechanical ...

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

Training Manual

Step 6 – Generate the Default Mesh

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

Training Manual

Step 7 – Change the Mesh Method

7.a Insert a Meshing Method

7.b Select all bodies (RMB in the view area)

7.c Deselect the Bird body (<control> + SC on body) RMB <control> + SC SC RMB SC

Training Manual

Step 7 – Change the Mesh Method …

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

SC RMB

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Step 8 – Define the Initial Conditions

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

RMB

SC

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Step 8 – Define the Initial Conditions ...

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Step 9 – Define the Analysis Settings

9.a Select Analysis Settings in the tree

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

SC

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

Training Manual

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 10.b Open the AUTODYN project, RMB SC D&D

Training Manual

Step 11 – Generate an SPH Part for the Bird

11.c Enter

“Bird_SPH” for the Part Name 11.d Select the

SPH Solver

11.e Accept the data 11.a Select Parts On Navigation Bar 11.b Select New in the

Training Manual

Step 12 – Create an SPH Object from the Bird Part

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”

Training Manual

Step 13 – Delete the (Lagrange) Bird Part

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

Training Manual

Step 14 – Pack SPH_Bird Object with SPH Nodes

14.a Select Pack (Fill) 14.b Select the SPH_Bird object 14.c Select Pack Selected 14.d Check Fill with Initial Condition Set

14.e Select Initial Condition Set 3 (Water and 250 m/s) 14.h Accept the data 14.f Select next 14.g Enter 15.0 mm for the Particle Size

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Step 15 – Load a Plot Settings File

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

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Step 16 – Set up the Bird / Wing Interaction

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

Training Manual

Step 17 – Run the Analysis

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)

The calculation takes

approximately 40 minutes to run to completion (about 7500 cycles)