Ansys Workshop 5

8/13/2019 Ansys Workshop 5

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Workshop 5:

Modal Analysis of aModel Airplane Wing

University of Puerto Rico at Mayagez

Department of Mechanical Engineering

Modified by (2008): Dr. Vijay K. GoyalAssociate Professor, Department of Mechanical Engineering

University of Puerto Rico at Mayagez

Thanks to UPRM students enrolled in INME 4058

sections 2006-08


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Material: Low density polyethylene

Properties:

E (Young's modulus): 38 x 103psi

(Poisson's ratio): 0.3 (Density): 8.3 x 10

-5lbf-sec2/in4

Problem Description (cont.)


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Starting ANSYS

From your desktop:

Click on: START > Al l Programs >

ANSYS 10.0 >

ANSYS Product Launcher.

Here we will set our Working Directory

and the Graphics Manager


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This is the

10.0 ANSYS

Product Launcher

main window.

Select the Work ing

Directoryand type

the name of work

shop on Job Name.

Working Directory Setup


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Click the button:

Customization/Preferences.

On the item of Use custom

memorysettings type 128on Total Workspace (MB):

and type 64 on

Database (MB):

Then click the Run

bottom.

Graphics Setup

* This setup applies to computers running under 512 MB of RAM


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This is ANSYSs Graphical User Interface window.

ANSYS GUI Overview


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Well set preferences in order to filter quantities that relate to this discipline only.

Click PreferencesfromANSYS Main Menu.

Select (check): Structural & h-Method

Step 1: Set Preferences


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Define element types (Well select two element types)

1. ANSYS Main Menu > Preprocessor > Element type > Add/Edit/Delete

2. Click ADD

Adding First Element Type

3. Structural Mass > Solid family of elements. Choose Quad 4node (PLANE42). Click App ly*PLANE42: is used for 2-D modeling of solid

structures. The element can be used either as

a plane element (the stress or plane strain)

or as an axisymmetric element. The element

Is defined by four nodes having two degrees

of freedom at each node: translations in the

nodal x and y directions. The element hasplasticity, creep, swelling, stress stiffening,

large deflection, and large strain capabilities.

Well use this element type to define the

wings mesh on the sectional area.

Step 2: Element Type


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Adding Second Element Type

4. Structural Mass > Solid family of elements. Choose Brick 8node (SOLID45). Click App ly

5. Click Apply> OK> Close

*SOLID45:is used for the 3-D modeling

of solid structures. The element is

defined by eight nodes having three

degrees of freedom at each node:

translations in the nodal x, y, and z

directions.

Well use this element type to

define the mesh along the extruded

solid surface of the wing



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You should have two element types on the Element Typeswindow


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In this section well define the wings constant material properties. Well select the

materials behavior and then well define Youngs Modulus (E), poisons ratio (), and

density ().

1. ANSYS Main Menu > Preprocessor > Material Properties > Material Models

2. (Double-click on) Structural > Linear > Elastic > Isotropic

Step 3: Define Materials


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3. Enter: EX: 38000

PRXY: 0.3

4. Click OK

5. (Double-click on) Density

6. Enter: DENS: 8.3E-5

7. Click OK

8. Utility Menu > Material > Exit

Step 3: Define Materials


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Well start by creating keypoints,these well define the sectional area for our wing.

Keypoints: These are points, locations in 3D space.

1. ANSYS Main Menu > Preprocessor > Modeling > Create > Keypoints > In active CS

2. Enter 1for Keypoin t Number, enter 0,0,0 forX,Y,Zrespectively. Click App ly

Step 4: Build Geometry


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3. Enter 2for Keypoin t Number, enter 2,0,0 forX,Y,Zrespectively. Click Apply

4. Enter 3 for Keypoin t Number, enter 2.3,0.2,0forX,Y,Zrespectively. Click Apply

5. Enter 4 for Keypoin t Number, enter 1.9,0.45,0forX,Y,Zrespectively. Click App ly

6. Enter 5 for Keypoin t Number, enter 1.0,0.25,0forX,Y,Zrespectively. Click App ly

7. Click OK

Display Window

after creating all five Keypoints

Notice that for all 1-5 keypoints, Z-values

are always 0. This makes sense since

sectional areas are always on 2D-plane.

(X-Y planes for our case)



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Next, well create lines and curves (splines) that will connect the keypoints, thus

creating the geometric outline of the wings sectional area.

Well start by creating straight lines from point 1-2 and 1-5.

1. Main Menu > Preprocessor > Modeling > Create > Lines > Straight Lines

This feature creates a straight line between two points.

2. Select keypoints 1 and 2.

Click Apply

3. Select keypoints 1 and 5.

Click Apply



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Next, well create a line curve or Splinethat connects keypoints2, 3, 4 and 5.

4. ANSYS Main Menu > Preprocessor > Modeling > Create > Lines > Splines

> with options > spline thru KPs

When selecting with options, gives the preference to specify the slope vector at which the splineenters

each connecting keypoint.

5. Pick Keypoints 2,3,4,5. Click Apply

6. Enter:

Slope of spline entering @ keypoint 1

XV1= -1 YV1= 0 ZV1= 0

Slope of spline entering @ keypoint 5

XV6= -1 YV6= -0.25 ZV6= 0

Again, notice that Z-values are 0 since

were working on X-Y planes.

7. Click OK



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When finished, the wings outline geometry should look like this.

Next well proceed on filling the outlined geometry with an actual sectional area or body.



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To generate an area bounded by the previously created lines do as follows:

1. ANSYS Main Menu > Preprocessor > Modeling > Create > Areas > Arbitrary > By lines

2. Pick all 3 lines. Click OK

By selecting all three lines were forming a closed loop which will bound our sectional area.



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Your wing should look like this:



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Here well define the meshing for our wing model.1. ANSYS Main Menu > Preprocessor > Meshing>Mesh Tool.

2. Under Size Con trol, set the Global Size.

3.Enter:

SIZE Element edge length: 0.25

NVID No. of element divisions: 0

4. Click OK

Step 5: Create Mesh


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5. Click Mesh

6. Be sure to pick the enclosed area.

7. Click OK

Step 5: Create Mesh


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Now well extrude a mesh volume using our second element type (solid 45).

1. ANSYS Main Menu > Preprocessor > Modeling > Operate > Extrude > Elements ext opts.

2.Choose 2 (SOLID45) for Element typ e number.

3. Enter 10for number of element divisions.

4. Click OK

Step 5: Create Mesh


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5. ANSYS Main Menu > Preprocessor > Modeling > Operate > Extrude > Areas

> By XYZ offset

6.Pick All (in picking menu)

7.Enter 0,0,10 for offsets for extrusion in the Z direction

8. Click OK. Then click Closeon the Warning window.

Step 5: Create Mesh


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Before applying constraints to the fixed end of the wing, unselect

all PLANE42 elements used in the 2-D area mesh since they will

not be used for the analysis.

1. Utility Menu > Select > Entities.

2. Choose Elementson first scroll down.

3. Choose by Attr ibuteson second scroll down.

4. Choose Elem typ e num.

5. Enter 1on Min , Max, Incbox.

6. Choose Unselect.

7. Click Apply, then Ok.

Step 6: Apply Loads


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Constraints will be applied to all nodes located where the wing is

fixed to the body. Select all nodes at z = 0, then apply the

displacement constraints.

1. Utility Menu > Select > Entities

2. Choose Nodeson first scroll down.

3. Choose By Locat ionon second scroll down.

3. Choose Z coord inate.

4. Enter 0 on Min , Max, Incbox.

5. Choose From Ful l.

6. Click Apply, then Ok.

Step 6: Apply Loads


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7. ANSYS Main Menu > Preprocessor > Loads >Define Loads> Apply > Structural >

Displacement

> On Nodes

8. Pick All to pick all selected nodes.

9. Choose All DOF

10. Click OK

Step 6: Apply Loads


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Specify Analysis Type and Options

1. ANSYS Main Menu > Solution > Analysis Type > New Analysis

2. Choose Modal

3. Click OK

Step 7: Obtain Solution


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4. ANSYS Main Menu > Solution > Analysis type > Analysis Option

5. Ensure Block Lanczosis selected

(Block Lanczos is the default for a modal analysis.)

6. Enter:

No. of nodes to extract: 5

No. of nodes to expand: 5

7. Click OK

8. Frequency Range: 1500

9. Click OK



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1. ANSYS Main Menu > Solution > Solve > Current LS

2. Close the Notewindow.

3. Close the/STATUS Commandwindow



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List the natural frequencies

1. ANSYS Main Menu > General PostProc > Results Summary

2. Close after observing the listing.

*This listing shows the five different frequency analysis done by ANSYS

Step 8: Review Results


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Animate the 5 different modes shape

The following shows the animation results for the first frequency mode

1. ANSYS Main Menu > General PostProc > Read Results > First Set

*If you want to obtain a different frequency animation, you need to select which one using

ANSYS Main Menu > General PostProc > Read Results > By Pick

2.Utility Menu > Plot Crtls > Animate >

Mode Shapes



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3. Enter: No. of frames to create: 10

Time delay (seconds): 0.5

4. Click OK



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Step 8: Review ResultsNow the window shows the animation per frame and time selected

for the wing. Notice the forces reflected on the wing. This is an

excellent way to review the design.

Documents

Ansys Workshop 5