Lesson 6 - Fea II

8/3/2019 Lesson 6 - Fea II

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Lesson Six: FEA II

Open I-DEAS and create a model file called FEA_project.mf1 and

make the ApplicationSimulation and TaskMaster Modeller

Make sure the Units are in mm (newton) using Options\Units

Idler ArmRemoving Features

In the Manage Bins form use the Get from Library function to copy the part Idler

Arm from the Engg2100project and the libraryTutorial Parts. Bring the Idler arm out on to

the workbench.

We want to simplify the part by removing some of the more complicated features:

Select the delete button and zoom in on the bottom hole of the Idler Arm and double click(some features need three clicks) on the feature by choosing either the edge or center line of the

hole. Update the part.

Partitioning the Part

Zoom in on the bottom hole of the Idler Arm and Sketch in Place on the front face of the

bottom hole and draw a line across the bottom cylinder.

Select the Extrude button and select the entire line . Select the Partition option and

Through All.


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Making Copies of Your Part

After you create and solve an FE model your part will be locked by the results. One way of

getting around this problem (if you want to make multiple FEAs or modify your part later on)

is to create copies of your part.

Select the move button and then click on the part .

Click the Copy sw option and select On, select Slide OnScreen, hold the left mouse button down and make a line

running across the screen, then type the number 2 in the

Prompt window .

Name the new two parts: Idler2 and Idler3

Put away the Idler2 and Idler3 into your bin.

You can also make copies of your part using your mange bins form . Select the Idler Arm

part and then the copy button. Name the new part something original.

Creating the FE Model

Change the taskto

Boundary Conditionsand select the Create FE

model .Toggle on the

Geometry Based Analysis

Only option and using the

mdla98 database change

the material to Titanium

Ti-6AL-4V


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Use the displacement restraint button to restrain the top face of the Idler

Arm.

Use the Force button and apply a 100N compressive force on the upper

surface of the bottom hole.

Create a boundary condition

set . In the Boundary

Condition Set form change the

Boundary Condition Type to

Linear Statics-Adaptive and

toggle on the Restraint Set and

highlight the LOAD SET 1.

Change the tasktoMeshing.

Select the Solid Meshing button

and select both the top and bottom

volume.

Change the element length to

10mm.

Select the Googly Eyes .


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Check the element quality before you keep a

mesh by first choosing the Mesh Generate

button on the Modify Mesh Preview

form.

Next, select the Element Quality button

and within the Element Quality Checks form

toggle on the Distortion and Stretch options.

Select the Graphing button to bring up theElement Quality Statistics form. Select the Green

button to generate the statistics for Distortion.

The Minimum Distortion must be positive for

your model to solve. If the Distortion minimum

is positive keep the mesh, if it is negative cancel

the mesh and make the mesh smaller and check

the distortion again.

Changing the Display Options

In order to better show

the mesh fit to your part

you can change theviewing options by

selecting the Shaded

Options button under

the Shaded Hardware

button . Within the

Shaded Options form select the

outline to be Black.


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Change the tasktoModel Solution and select the Solution Set button.

Create a new solution set,

select the Output Selection

button within the Solution Set

form. Highlight the Output

Type Strain and select Store.Next, select Options within the

Solution Set form and change

the Energy/Error Norm

(percent) value to 10.

Commonly, the strain energy

in a critical area of interest

should not have averaged

results differing by more than

10%. This is a maximum

value you might want to try

minimizing this value to 5%

for your model.

Save your model, select the Solve button . After your model has solved select the

Visualizer button. As you can see from the picture below the default settings are not the

best for displaying your results.


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Visualizer Settings

Select the Colour Bar button , change the # Bands to 10

and the Style to Stepped in the colour Bar form.

Next select the

Deformed/Undeformed Options

button which lies under the

Deformed button.

In the Deformed/Undeformed Options form change

the option from Maximum Deformation (% of Model)

to Scale Factor = 1.

Next, deselect the Element Border option

Select the Header button

and select the All off button

on the Header form.

Within the Visualizer tool bar select the Text

button which lies under the Header button.

Change the Font to Arial, the weighting to Bold, the text

Size to 16, and the Format to x.xE+xx


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The display changes will make your results a lot easier to view. The adaptive mesh will create

more elements around the top key hole where the stress gradient is highest.

To change the results to Displacement use the Select

Results button located on the Visualizer Tools

bar.

Select the ? within the Display options and highlightthe DISPLACEMENT results

PrintingThere are three easy ways of getting pictures off of I-

DEAS. You can choose the Print button on the

Visualizer tool bar, use Print Screen on your

keyboard, or download a trial version of the software

package SnagIt.

For more information on the FEA runs you can look at the *.lis file located on your H:\ drive

and you can use the Info button to look at information regarding the model (#nodes &

elements) on the workbench using the right mouse button and selecting the Workbench (Full)

option. The results are listed in the I-DEAS List window.

Idler Arm FEA Study

- load 100N compression- 3564 elements- 6643 nodes- total time 36 seconds-

Max average strain energy = 9.09%Displacement Stress & Strain Mesh


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Thin Shell Meshing

If you have a part that has a >10:1 length/thickness you will want to use 2D shell meshing. In

this situation you can assume that the thickness will remain constant in bending.

Perform the online tutorial: Modeling a Plastic Part up to pg. 50 in I-DEAS under Design, Part

Modeling: 2. Advanced Projects or go to the library Tutorial Parts in the Engg2100 Project

in the Tutorial Parts library and copy the part Plastic Part

Open I-DEAS and create a model file called Shell.mf1 and make the

ApplicationSimulation and TaskMaster Modeller. Make sure you have

the Plastic Part on the screen.

Make sure the Units are in mm (newton)

We should make a few simplifications to the Plastic Part before we proceed:

Select the History Access button then the part.

Shift pick the 7 operations (indicated to the right) performed

on the Plastic Part and Delete them. Update the part

Before After

The easiest method of creating a shell mesh is to delete all

the inner surfaces of a model. This leaves an open part that has no volume.

Shift select all 16 (including the inside surfaces of the two rectangular holes) of the bottom

surfaces of the Plastic Part then select the Erase button. The result will be dark and hard to see

from the bottom. Go to Options under the Shaded Hardware button. In theShaded Options form click on the Hardware support and toggle on the Hardware

backlighting button.


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Select the front face of the step

between the lower and upper level of

the part.

Draw three lines on this face.Separate the lines from the edge of the

part and each other by 68mm

Next, select the Extrude button then

each of the three lines you just created.

On the extrude form click on the arrow

next to the Direction Vector and

choose Visible.

Select the top edge of your part and

make sure the direction is the same as

shown below.


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Within the extrude

form choose the option

Until Next and select

the back surface of the

plastic part.

Sketch on the upper

plane of the plastic part

and create a 20mm

diameter circle in the

middle of the

rectangular surface

shown.

Select the circle to

extrude and change the

settings to Split surface

and make the selectivity

Surfaces.

Once you change theselectivity to surfaces

you need to select the

upper surface of the part.

This operation splits the surface so that you now have a circular surface on the upper surface

that you can select for loading.


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Change the tasktoBoundary Conditions and

select the Create FE model Toggle on the

Geometry Based Analysis Only option, create a

material with called Polycarbonate with a

Modulus of Elasticity = 8.3E9 Pascals,

Poissons Ratio = 0.38, and Shear Modulus =

Null Property

Use the Displacement Restraint button to

restrain the bottom edge of the Plastic Part

Choose the Pressure button and select the circle on the top surface

Change the

Pressure on Surface

form to Total Forceand make the force

-25N.

Make a Boundary

Condition Set

with the Boundary Condition Type set to Linear Statics

Adaptive , select the Restraint Set, and highlight the Load Set.

Change the Task to

Meshing.

Select the Physical

Properties button

Create a 2D element

with the constant

thickness of 2mm.


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Select the Define Shell

Mesh button . Select

all the surfaces on the

plastic part. In the Define

Mesh form make the

element length 6mm and

select the Free Optionsbutton.

Make sure the Curvature

Based Length option is set

to None.

Check to make sure the element quality is positive, follow the same procedure for solving the

model as outlined in the Idler Arm drawing task. Create the same figures as below.

Plastic Part FEA Study

- load 25N compression- 3012 elements- 3139 nodes- total time 27 seconds- Max average strain energy = 9.47%

Displacement Stress & Strain

Mesh

Lesson 6 - Fea II

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