Stress Analysis INVENTOR

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Chapter 1 Part Modal and Stress Analysis . . . . 1

Simulation 1: About this tutorial . . . . 1

Open the Model for Modal Analysis . . . . 3

Enter the Stress Analysis Environment . . . . 3

Assign Material . . . . 4

Add Constraints . . . . 4

Preview Mesh . . . . 6

Run Simulation . . . . 7

View the Results . . . . 7

Summar y . . . . 11

Simulation 2: About this tutorial . . . . 12

Copy Simulation . . . . 13

Create Parametric Geometry . . . . 14

Include Optimization Criteria . . . . 16

Add Loads . . . . 16

Set Convergence . . . . 17

Run Simulation . . . . 18

Summar y . . . . 21

Chapter 2 Assembly Stress Analysis . . . . 23

About this tutorial . . . . 23

Get Started . . . . 25

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Stress Analysis Environment . . . . 25

Excluding Components . . . . 26

Assign Materials . . . . 27

Add Constraints and Loads . . . . 28

Stress Analysis Settings . . . . 31

Contact Conditions . . . . 32

Generate Meshes . . . . 33

Run the Simulation . . . . 34

View and Interpret the Results . . . . 35

Summar y . . . . 37

Chapter 3 Contacts and Mesh Refinement . . . . 39

Open the Model . . . . 40

Stress Analysis Environment . . . . 41

Create a Simulation . . . . 41

Exclude Components . . . . 42

Add Constraints and Loads . . . . 43

Define Contact Conditions . . . . 46

Specify and Preview Meshes . . . . 50

Copy and Modify Simulation . . . . 54

Specify Local Mesh Controls . . . . 54

Run the Simulation Again . . . . 56

View and Interpret the Results Again . . . . 57

Summar y . . . . 59

Chapter 4 Assembly Modal Analysis . . . . 61

Open the Assembly . . . . 64

Create a Simulation Study . . . . 65

Exclude Components . . . . 66

Create Manual Contacts . . . . 68

Specify Mesh Options . . . . 70

Preview Mesh and Run Simulation . . . . 70

View and Interpret Results . . . . 71

Summar y . . . . 73

Chapter 5 FEA Assembly Optimization . . . . 75

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Define the Simulation . . . . 77

Adding Constraints . . . . 78

Adding Loads . . . . 79

Modify the Mesh . . . . 80

Preview the Mesh . . . . 81

Create Parametric Geometry . . . . 82

Optimization Criteria . . . . 84

View and animate 3D plots . . . . 87

View XY Plots . . . . 88

Summar y . . . . 90

Chapter 6 Stress Analysis Contacts . . . . 93

Overview . . . . 94

How a Caulk Gun Works . . . . 96

Assembly Simulation . . . . 99

Contact Types . . . . 100

Bonded Contact . . . . 102

Separation Contact . . . . 103

Sliding and No Separation Contact . . . . 104

Separation and No Sliding Contact . . . . 107

Shrink Fit and No Sliding Contact . . . . 108

Spring Contact . . . . 110

Loads and Constraints . . . . 111

Simulation Results . . . . 112

Summary . . . . 114

Chapter 7 Frame Analysis . . . . 117

Frame Analysis Environment . . . . 119

Frame Analysis Settings . . . . 122

Change Beam Properties . . . . 124

Change Direction of Gravity . . . . 124

Add Constraints to the Next Beam . . . . 128

Add Loads . . . . 129

View and Interpret Results . . . . 132

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Summary . . . . 133

Chapter 8 Frame Analysis Results . . . . 135

Get Started . . . . 136

Display Maximum and Minimum Values . . . . 140

View Beam Detail . . . . 141

Display and Edit Diagrams . . . . 142

Adjust Displacement Display . . . . 144

Animate the Results . . . . 146

Generate Report . . . . 147

Summary . . . . 148

Chapter 9 Frame Analysis Connections . . . . 149

Connections Overview . . . . 150

Change Direction of Gravity . . . . 154

Add Custom Nodes . . . . 154

Add Custom Nodes . . . . 157

Change Color of Custom Nodes . . . . 159

Assign Rigid Links . . . . 160

Assign a Release . . . . 167

Run the Simulation Again . . . . 169

View the Updated Results . . . . 170

Summary . . . . 171

Chapter 10 Modal Type of Frame Analysis . . . . 173

Create a Simulation Study . . . . 175

Animate the Results . . . . 178

Summary . . . . 179

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Degrees of Freedom . . . . 183

Automatic Constraint Conversion . . . . 184

Assembly Constraints . . . . 187

Add a Rolling Joint . . . . 189

Building a 2D Contact . . . . 190

Add Spring, Damper, and Jack Joint . . . . 193

Define Gravity . . . . 195

Impose Motion on a Joint . . . . 196

Run a Simulation . . . . 197

Using the Output Grapher . . . . 198

Simulation Player . . . . 199

Summary . . . . 202

Chapter 12 Dynamic Simulation - Part 2 . . . . 205

Work in the Simulation Environment . . . . 206

Construct the Operating Conditions . . . . 208

Add Friction . . . . 210

Add a Sliding Joint . . . . 212

Use the Input Grapher . . . . 213

Use the Output Grapher . . . . 217

Export to FEA . . . . 219

Publish Output in Inventor Studio . . . . 223

Summary . . . . 225

Chapter 13 Assembly Motion and Loads . . . . 227

Open Assembly . . . . 229

Activate Dynamic Simulation . . . . 231

Automatic Joint Creation . . . . 231

Define Gravity . . . . 232

Insert a Spring . . . . 232

Define the Spring Properties . . . . 235

Insert a Contact Joint . . . . 237

Edit the Joint Properties . . . . 239

Add Imposed Motion . . . . 241

View the Simulation Results . . . . 241

View the Simulation Results (continued) . . . . 242

Export the Data . . . . 243

Summary . . . . 244

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Chapter 14 FEA using Motion Loads . . . . 245

Open Assembly File . . . . 247

Run a Simulation . . . . 249

Generate Time Steps . . . . 249

Export to Stress Analysis . . . . 249

Use the Motion Loads in Stress Analysis . . . . 253

Generate a report . . . . 256

Summary . . . . 257

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Part Modal and Stress

Analysis

Simulation 1: About this tutorial

Modal analysis. Simulation Category 20 minutes Time Required

1

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PivotBracket.ipt Tutorial Files

Used

You will create two simulations: modal analysis of the part and a parametric structural static analysis on the same part.

The Modal Analysis tutorial walks through the process of defining and performing a structural frequency analysis, or modal analysis, for a part. The simulation generates the natural frequencies (Eigenvalues) and corresponding mode shapes which we view and interpret at the end of the tutorial.

The second simulation is a parametric study on the same model. Parametric studies vary the design parameters to update geometry and evaluate various configurations for a design case. We perform a structural static analysis with the goal of minimizing model weight.

Objectives

■ Create a simulation for modal analysis

■ Override the model material with a different material

■ Specify constraints

■ Run the simulation

■ View and interpret the results

Prerequisites

■ Familiarity with the ribbon user interface and Quick Access Toolbar.

■ Familiarity with the use of the model browser and context menus.

■ See the Help topic “Getting Started” for further information.

Navigation Tips

■ Use Show in the upper-left corner to display the table of contents for this tutorial with navigation links to each page.

■ Use Forward in the upper-right corner to advance to the next page.

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Open the Model for Modal Analysis

Let’s get started on the Modal Analysis simulation first.

1 On the Quick Access Toolbar, click the Open command. 2 Set your project file to Tutorial_Files.ipj if not already set. 3 Select the part model named PivotBracket.ipt.

4 Click Open.

Previous (page 1) | Next (page 3)

Enter the Stress Analysis Environment

The stress analysis environment is one of a handful of Inventor environments that enable specialized activity relative to the model. In this case, it

incorporates commands for doing part and assembly stress analysis. To enter the stress analysis environment and start a simulation:

1 Click the Environments tab in the ribbon bar. The list of available

environments is presented.

2 Click the Stress Analysis environment command. 3 Click Create Simulation.

4 The Create New Simulation dialog box displays. Specify the name Modal Analysis.

5 In the Simulation Type tab, select Modal Analysis.

6 Leave the remaining settings in their current state and click OK. A new

simulation is started and the browser is populated with stress analysis-related folders.

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Assign Material

For any component that you want to analyze, check the material to make sure that it is defined. Some Inventor materials do not have “simulation-ready” properties and need modification before using them in simulations. If you use an inadequately defined material, a message displays. Modify the material or select another material.

You can use different materials in different simulations and compare the results in a report. To assign a different material:

1 In the ribbon bar, in the Material panel, click Assign Materials. 2 Click in the Override Material column to activate the drop-down list. 3 Select Aluminum-6061.

4 Click OK.

NOTE Use the Styles and Standards Editor to modify materials if they are not

completely defined. You can access the editor from the lower left corner of the Assign Materials dialog box.

Add Constraints

Next, we add the boundary conditions, a single constraint on the interior cylindrical face.

To add the constraint:

1 In the ribbon bar, in the Constraints panel, click the Fixed Constraint

command. The docked dialog box displays.

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3 Click OK.

The model is now constrained by that face. The browser constraints folder is populated with a node representing the constraint.

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Preview Mesh

Before starting the simulation, we can view the mesh.

1 In the ribbon bar, Prepare panel, click Mesh View.

The command is a toggle between model view and mesh view.

2 To return to the model, click Mesh View again.

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Run Simulation

Now, to run the simulation.

1 In the Solve panel, click the Simulate command to display the Simulate

dialog box.

2 Check the More section of the dialog box for messages. Click Run to

display the simulation progress. Wait for the simulation to finish.

View the Results

After the simulation finishes, the Results folder populates with the various results types. The graphics region displays the first mode shaded plot. In the browser under the Results node and then the Modal Frequency node, notice the first mode shape (F1) has a check mark by it, indicating it is being displayed. There are nodes for the mode shapes corresponding to each natural frequency. The color chart shows relative displacement values. The units are not applicable since the mode shapes values are relative. (They have no actual physical value at this point.)

Now you can perform post-processing tasks using the Display commands located on the ribbon bar. The commands are described in Help.

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For post-processing of structural frequency simulation studies, the browser list shows the natural frequencies. Double-click any of these nodes to show the corresponding Mode Shape 3D plot.

1 Animate the results using the Animate Results command in the Result

panel on the ribbon bar.

2 While the animation is playing, click Orbit in the navigation tools on

the side of the graphics window. As you orbit the graphics, the animation continues to play.

NOTE The following image depicts a frame from the animation of mode F3.

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3 Click OK.

4 In the Results browser list of natural frequencies, double-click the results

for mode F3 to display that mode.

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NOTE If you plan to complete the second part of this tutorial, keep this model file

open. Otherwise, save your model file to a different name before you close it.

Summary

In this first tutorial for Part Stress Analysis, you learned how to:

■ Create a simulation for modal analysis.

■ Override the model material with a different material.

■ Specify constraints.

■ Run the simulation.

■ View and interpret the results.

What Next? Continue with “Simulation 2 - Parametric Static Analysis”

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Parametric static analysis.

Level 3 special interest Skill Level 20 minutes Time Required PivotBracket.ipt Tutorial Files Used

The second simulation is a parametric study on the same model. Parametric studies vary the parameters of the model to update geometry and evaluate various configurations of a design. In this structural static analysis, the goal is to minimize the weight of the model.

Objectives

■ Copy a simulation.

■ Use analysis parameters to evaluate how to refine the weight of the model.

■ Generate configurations of the parametric dimension geometry.

■ Modify design constraints and view results based on those changes.

Prerequisites

■ Completed Simulation 1 (Modal Analysis), the first part of this tutorial set.

Navigation Tips

■ Use Show in the upper-left corner to display the table of contents for this tutorial with navigation links to each page.

■ Use Forward in the upper-right corner to advance to the next page.

Copy Simulation

We will create a copy of the first simulation, and edit it to define the second analysis.

1 In the browser, right-click the Simulation (Modal Analysis) node

and click Copy Simulation. A copy of this simulation is added to the browser and becomes the active simulation.

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We will edit the simulation properties to define a parametric dimension study.

2 Right-click the newly created Simulation node, and click Edit Simulation Properties.

3 Change the name to Parametric.

4 Change the Design Objective to Parametric Dimension using the

drop-down list.

5 Set the simulation type to Static Analysis. 6 Click OK.

Create Parametric Geometry

We will produce a range of geometric configurations involving the thickness of the model to facilitate weight optimization. Adding parameters to the parametric table is required.

Add parameters to the parametric table

1 In the Manage panel, click Parametric Table.

2 In the browser, right-click the part node just below the Simulation (Parametric) node, and click Show Parameters.

3 In the Select Parameters dialog box, check the box to the left of the

parameter named d2, 12 mm.

4 Click OK.

After identifying the parameter we want to use, we must define a range for the parameter and generate the corresponding geometric configurations.

Define parameter range

1 In the Values cell for Extrusion1 d2, enter the range 6-12. The values

must be in ascending order.

2 Press Enter to accept the values. When you click inside the Value field,

the value now says 6-12:3. This indicates that there are now three values in the range. These are equally divided between the first and last number, hence that values are 6, 9, and 12.

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NOTE The number after the colon specifies the additional configurations

desired, excluding the base configuration. The base is 12 mm, and the two additional configurations are 6 mm and 9 mm.

Once the parameter range is specified, we can generate the various configurations based on the range values.

Generate configurations

1 Right-click the table parameter row, and select Generate All Configurations. The model generation process is started.

2 After the model regeneration is completed, move the slider to see the

different shapes created.

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We are not finished with the Parametric Table yet, so do not close it.

Include Optimization Criteria

Remember that our goal for this simulation is to minimize weight. We optimize the simulation using a range of geometric configurations generated previously while utilizing the Yield Strength failure criteria.

Add Design Constraints

1 In the Design Constraints section, pause the cursor over the empty

row, right-click, and click Add Design Constraint.

2 In the Select Design Constraint dialog box, click Mass, and click OK. 3 Repeat step 1.

4 In the Select Design Constraint dialog box, Select Von Mises Stress.

Ensure that Geometry Selections is All Geometry.

5 Click OK.

Enter Limit values and safety factor

1 In the Von Mises Stress row, click in the Constraint type cell, and

select Upper Limit from the drop-down list.

2 Enter 20 for Limit.

3 Enter 1.5 for Safety Factor .

Add Loads

Next, add the structural load.

1 Click the Force Load command. The dialog box displays. 2 Select the face as shown.

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3 Enter 200 N for the Magnitude. 4 Click OK.

Set Convergence

The software performs an automatic H-P refinement for parts. In this case, we want to add an additional H refinement iteration. H refinement increases the number of mesh elements in areas where the results need improvement. The P refinement increases the polynomial degree of the selected elements in the high stress areas to improve the accuracy of the results.

1 In the Prepare panel, click Convergence Settings. 2 For Maximum Number of h Refinements, enter 1. 3 Click OK.

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Run Simulation

Now we will run the simulation. To start the Simulation, use the Simulate command in the ribbon bar or through the simulation node context menu.

1 Click the Simulate command to display the Simulate dialog box. 2 Click Run. The Simulation progress displays. Wait for the simulation

to finish.

When the simulation is complete, the Von Mises Stress plot displays by default.

3 In the Display panel, click Adjust Displacement Display , drop-down list, and select Actual.

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View the Results

After the simulation finishes, the graphics region displays a 3D color plot, and you can see that the Result folder is populated. Now we can evaluate the results through the parametric table and the 3D and XY plots available for post processing.

Optimize model

First, we optimize the mass using the parametric table populated in previous steps. Then we look at 3D and XY plots to understand the behavior of the model under the defined boundary conditions.

The goal is to minimize the mass of the model taking into account parametric dimensions and stress constraints.

1 If you previously closed the Parametric table, reopen it by clicking the Parametric Table command.

2 For the Mass Design Constraint, click in the Constraint Type cell,

and select Minimize from the drop-down list.

The parametric values change to show the configuration with the least mass that meets the given constraints. In this case, the original thickness value was

12 mm and the optimized value is 9 mm which in turn reduces the mass of

the model.

Note the design constraint Result Value for Max Von Mises Stress. The value has a green circle preceding it. It indicates that the design constraint value is within the safety factor range.

Slide the Extrusion1 parameter value to 6. When the table updates, you will see that the design constraint Result Value is now outside the safety factor. The value is preceded by a red square indicating the design constraint value has been exceeded the safety factor. Slide the parameter value back to 9.

View and animate 3D plots

Now you can perform post-processing tasks using the Display panel commands for smooth shading, contour plots, etc. These commands are described in Help.

1 In the Result panel, click Animate Results.

2 In the Animate dialog box, click the Play command. The Von Mises Stress plot colors change to reflect the application of the load. To

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view the deformation changes, stop the animation, select Adjusted x1 from the Adjust Displacement Display , drop-down list and restart the animation.

For post-processing of results, double-click the result in the browser to display the result in the graphics region. Then, select the Display command you want to use.

View XY graphs

XY Charts show a result component over the range of a parameter.

To view an XY plot, right-click over the parameter row in the Parametric Table and choose XY Plot.

In this case, the above XY plot displays Stress results versus parametric configurations.

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Summary

In this last tutorial for Part Stress Analysis, you learned how to:

■ Copy a simulation.

■ Modify the simulation properties to change the type of simulation.

■ Generate configurations of the parametric dimension geometry.

■ Use analysis parameters to evaluate how to refine the weight of the model.

■ Modify design constraints and view results based on those changes.

What Next? As a next step, consider doing the Assembly FEA tutorials. If

you have already completed them, why not acquaint yourself with the Dynamic Simulation tutorials?

Experiment with what you have seen and used. Explore how you can use this design tool to help you complete your digital prototype with confidence in its performance.

Previous (page 19)

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Assembly Stress Analysis

About this tutorial

Simulate the structural static behavior of an assembly for analysis.

Simulation Category 35 minutes Time Required

2

23

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analyze-2.iam Tutorial File Used

NOTE Click and read the required Tutorial Files Installation Instructions at ht-tp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed.

The stress analysis environment is a special environment within assembly, part, sheet metal, and weldment documents. The environment has commands unique to its purpose.

We analyze a subset of an assembly using the “exclude from simulation” functionality in Stress Analysis. Contact types are changed as required by the physical behavior of the model. Meshing settings are adjusted to capture the geometry of the model more accurately.

Objectives

■ Create a simulation.

■ Evaluate and assign materials as needed.

■ Add loads and constraints.

■ Identify contact conditions.

■ Create a mesh.

■ Run a simulation.

■ View and interpret the results.

Prerequisites

■ Know how to use the Quick Access toolbar, tabs and panels on the ribbon, model browser, and context menus.

■ Know how to navigate the model space with the various view tools.

■ Know how to specify and edit project files.

Navigation Tips

■ Use Next or Previous at the bottom-left to advance to the next page or return to the previous one.

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Get Started

To begin with, we will open the assembly to analyze. With Autodesk Inventor up and running, but with no model open, do the following:

1 Click the Open command on the Quick Access toolbar.

2 Set the Project File to Tutorial_Files.ipj 3 Select Assembly FEA 1 ➤ analyze-2.iam. 4 Click Open.

5 Save the file with a different name, such as: analyze-2_tutorial.iam

Stress Analysis Environment

We are ready to enter the stress analysis environment.

1 On the ribbon, click Environments tab ➤ Begin panel ➤ Stress Analysis .

2 On the Manage panel, click the Create Simulation command. The Create New Simulation dialog box displays.

The settings provide opportunity to tailor the simulation by specifying a unique name, single point or parametric dimension design objective, and other parameters.

NOTE On the Model State tab, you specify the Design View,

Positional, and Level of Detail to use for the simulation. The settings

can be different for each simulation.

3 Click OK to accept the default settings for this simulation.

The browser populates with a hierarchical structure of the assembly and analysis-related folders.

Most of the commands in the ribbon panels are now enabled for use. Disabled commands enable as their use criteria is satisfied.

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Excluding Components

You can exclude components that are not affected by the simulation or whose function is simulated by constraints or forces.

We will exclude the following parts from this simulation:

■ Handle

■ Screw

■ SHCS_10-32x6

To exclude these components:

1 Expand the analyze-2_tutorial.iam browser node. 2 Right-click Handle, and click Exclude From Simulation. 3 Repeat the command for both the Screw and SHCS_10-32x6

components.

The default display setting for excluded components is partially transparent as seen in the following image:

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Assign Materials

The next step is to look at the component materials and make adjustments. For this simulation, we will make a minor material change using materials that are fully defined.

Before you begin doing simulations, we recommend that you ensure your material definitions are complete for those materials being analyzed. When a material is not completely defined, the material list displays a symbol next to the material name. If you try to use the material, you receive a warning message.

If you attempt to edit a material during this tutorial, you may not be able to if the project setting Use Styles Library is set to No. To edit this setting, you cannot be working in the model. To change the setting requires exiting

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the tutorial. For purposes of this tutorial, use a material that is already fully defined. You can modify the other materials at a later time.

1 In the Material panel, click the Assign command. The dialog box displays the list of components, their material assignments, an override material, and a column showing how the material safety factor is defined.

2 In the Override Material column, click the first component

(Upper_Plate:1) cell to expose the material list.

3 In the list, click Steel.

4 Repeat the process for the all instances of the Upper and Lower plates.

Notice that when a components material is changed, all instances of that component inherit the change.

5 Click OK to exit the Assign Materials dialog box.

The browser Material folder receives a Steel folder added with all the components referencing that material listed within that folder. If you delete individual components from the folder, their material reverts to the assembly assigned material.

Add Constraints and Loads

Next we define the boundary conditions by adding structural constraints and loads. We start with constraints first.

1 In the Constraints panel, click Fixed . The dialog box displays with the Location selector active.

2 Select the two holes through which the screw passed. They are the holes

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3 Click OK. The two faces are axially constrained, as if the screw were

there.

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Now, we assign loads on the components.

1 In the Loads panel, click Force . The dialog box displays with the Location selector active.

2 Select the face on the ch_09-Upper_Grip component as shown.

3 In the dialog box, enter 100 for the Magnitude value, and click OK. 4 Repeat the previous steps for the ch_09-Lower_Grip component.

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5 Click OK to exit the Force dialog box.

Stress Analysis Settings

Stress Analysis settings apply to all new simulations. It is where you define the default settings that you saw in the Simulation Properties at the beginning of this process.

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In the Settings dialog box, you can specify:

■ Simulation Type

■ Design Objective

■ Contact Defaults

■ Excluded Component Display

■ Other parameters

Though we will not change the defaults for this tutorial, it is good to familiarize yourself with these settings. You can modify them for your future needs.

Contact Conditions

You can specify contact conditions either automatically or manually. Automatic contacts are generated according to the tolerance and contact type specified in the Stress Analysis Settings. You can assign other contact types such as Separation, Sliding / No Separation, and so on.

For this simulation, we automatically compute inferred contacts and then change some of those to another type.

1 In the Contacts panel, click Automatic . It detects the contacts within the default tolerance and populates the Contacts folder.

2 Expand the Contacts folder. You can see that all contacts were created

as Bonded contacts (default setting) and placed in a folder. Expand the

Bonded folder.

3 We must change the contacts listed in the following list. To make

changes, use multi-select. Select one contact, hold down the Ctrl key, and multi-select the remaining contacts in this list.

■ Bonded:1 (Upper Plate:1, Lower Plate:1)

■ Bonded:6 (Upper Plate:1, Pin A:3)

■ Bonded:10 (Upper Plate:1, Pivot Threaded:1)

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■ Bonded:26 (Lower Plate:1, Pivot Lower:1)

■ Bonded:32 Lower Plate:2, Pivot Lower:1)

4 Right-click a selected contact, and click Edit Contact. 5 Change the type to Sliding / No Separation, and click OK.

Generate Meshes

Before running the simulation, view the mesh to make sure that any areas needing a different mesh setting from the default are cared for. First, we will specify the mesh settings.

1 In the Prepare panel, click Mesh Settings . Alternatively, right-click the Mesh folder and click Mesh Settings.

2 Set Maximum Turn Angle = 30 to capture round areas of the

geometry.

3 Check Create Curved Mesh Elements.

4 If not already checked, check Use part based measure for assembly mesh.

This option uses the part size as mesh criteria, as opposed to a single size for all parts.

5 Click OK.

6 Having specified the mesh settings, you preview the mesh by clicking

the Mesh View command. The results are a mesh overlay on every part participating in the simulation.

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NOTE If areas of the model need a finer or more coarse mesh, add local mesh

controls. Local mesh controls are covered in another tutorial.

Run the Simulation

We are now ready to run the simulation.

1 In the Solve panel, click Simulate . The Simulate dialog box displays.

The dialog box more command >> exposes the messages section. If there are process steps to do, such as add constraints, the message is reported here.

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View and Interpret the Results

After the simulation completes, the graphics display presents the Von Mises Stress results plot. The complete set of results is posted in the Results folder. There are various commands for viewing result data. Most are located in the

Result and Display panels.

1 In the Display panel, click Show Maximum Value . In the graphics window, a label with a leader points to the location of the maximum value. In this example, the maximum value is obscured by other components.

2 Expand the assembly browser node to view the list of components. 3 Turn off visibility of the parts hiding the stress location.

■ Lower Plate:1

■ Upper Plate:1

Right-click each component, and click Visibility.

4 Rotate and Zoom as needed to view the location of the Maximum Value.

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Double-click the various results nodes to display the results in the graphics window.

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Summary

The previous image is what you see if you look at the Displacement results for this simulation.

Now that you have completed this tutorial, you have a basic understanding of the typical workflow in the stress analysis environment. This workflow includes:

■ Creating a simulation.

■ Excluding components not needed for the simulation.

■ Assigning materials as overrides of the existing material.

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■ Adding constraints and loads, sometimes called boundary conditions.

■ Adding contact conditions.

■ Generating meshes.

■ Running the simulation.

■ Viewing and interpreting the results.

What Next? As a next step, look into creating advanced contact conditions

and local mesh controls. The Contacts and Mesh Refinement tutorial takes you into these topics.

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Contacts and Mesh

Re-finement

About this tutorial

Use advanced and local mesh refinement to improve the stress results.

Simulation Category

3

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20 minutes Time Required

Bracket_Assembly.iam Tutorial File Used

Two simulations are covered. The first one corresponds to a structural static study with separation contact and advanced meshing settings. The second one involves additional local mesh control.

Objectives

■ Apply manual contacts.

■ Modify automatic contacts.

■ Add local mesh controls.

Prerequisites

■ Be familiar with the Stress Analysis environment, and complete the tutorial

Assembly Stress Analysis.

■ Know how to use the model browser and set the active project.

Navigation Tips

Next (page 40)

Open the Model

The first simulation walks, step by step, through the definition of a structural static FEA analysis. It includes the creation of manual contacts and selection of advanced meshing settings and concludes by viewing the results.

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2 On the ribbon, click Get Started tab ➤ Launch panel ➤ Open

.

3 Navigate to the Assembly FEA 2 folder, and then click Bracket_Assembly.iam.

4 Click Open.

Stress Analysis Environment

Switch to the Stress Analysis environment.

1 Click the Environments tab.

2 Click the Stress Analysis environment command.

Create a Simulation

Create a simulation.

1 Click Create Simulation , to display the Create New Simulation dialog box.

2 For the simulation Name, enter Separation Contact. 3 On the Simulation Type tab, specify Static Analysis.

4 Click OK. A new simulation named Separation Contact is created

and appears in the browser.

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Exclude Components

For this simulation, the Sleeve component is not relevant, so we will exclude it.

1 In the browser, expand the model node to reveal the components of the

assembly.

2 We want to evaluate the response to forces of the bolt when the Sleeve

component is not present. We must exclude it from the simulation. Right-click the Sleeve component and select the Exclude From

Simulation option. Alternatively, right-click the Sleeve component in

the graphics region, and click the command.

Assign Materials

The next step is to define the Materials. When a simulation is created, a

Material folder is included in the simulation structure. This Material folder

is populated whenever you specify override materials in place of the originally assigned material.

1 Double-click the Material folder. In the Assign Materials dialog box, a

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2 In the Override Material column, click the cell corresponding with

the Bolt component.

3 In the drop-down list, select Steel. 4 Right-click the cell, and click Copy.

5 For the following parts, multi-select the cells in the Override Material

column, right-click, and click Paste.

■ Bracket

■ Mount

■ Washer

■ Nut

NOTE All occurrences of the Washer are updated at one time. 6 Click OK.

Add Constraints and Loads

To define constraints and loads, use the commands available in the ribbon panels. Alternatively, right-click the browser node for the input type, and click the command there.

1 On the ribbon, click Stress Analysis tab ➤ Constraints panel

➤ Fixed.

The dialog box displays with the Face selector active.

2 Choose the appropriate faces. Multiple faces can be selected. In this case,

the faces represent a rigid attachment that occurs later in the manufacturing process.

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3 Click OK to complete the constraint inputs.

Add the second constraint:

1 Click the Fixed command.

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3 Click OK.

Next, we add a force or load. These steps define a condition where the assembly receives a constant load in a given direction.

1 Click Stress Analysis tab ➤ Loads panel ➤ Force.

The dialog box displays.

2 Choose the flat face at the bolt head.

3 Click the More command to expand the dialog box, and check Use Vector Components.

4 For the Fz component, enter 225. It defines the force magnitude and

direction.

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5 Click OK.

We now have defined materials, structural load, and constraints. In the browser, expand the Constraints and Loads nodes for viewing. Click a node to highlight the selection or location in the graphics window; and double-click to edit the definition.

Define Contact Conditions

You define contacts manually by selecting pairs of faces; these contacts are useful for cases in which the initial default contact tolerance is too small. Before manually adding contacts, use Automatic Contacts to detect the in-tolerance contact conditions.

1 In the Contacts panel, click Automatic . Contact conditions are automatically defined using the Contact defaults from the Stress Analysis Settings.

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As you manually add contacts, you choose from various contact types such as Separation, Sliding / No Separation, and so on.

We will now define manual contacts and set them to the Separation type. Additionally, we will modify two automatically created contacts to be the

Separation type.

1 Click the Manual command.

2 Set the Contact Type to Separation. 3 Select the faces for the new contacts as follows

a

In the graphics region, click the Bolt cylindrical face as selection

1.

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b

Move the cursor over the area where the Bolt component passes through the Bracket. When the cylindrical face on the Bracket highlights, click to select it.

c Click Apply.

d Reorient the model to do the same for the similar area near the

Bolt head.

e

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f

Move the cursor over the area where the Bolt component passes through the Bracket. When the cylindrical face on the Bracket highlights, click to select it.

g Click OK.

Now, we modify two automatic contacts to change them to the Separation contact type.

1 In the browser, expand the Contacts and then the Bonded folders. 2 Select contact Bonded:1, then hold down the Ctrl key and select

contact Bonded:2.

3 Over one of the selected contacts, right-click and select Edit Contact. 4 Select Separation from the Contact Type drop-down list. It assigns

the selected contact condition.

5 Click OK.

With the contact conditions defined, we can move to specifying the mesh settings.

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Specify and Preview Meshes

1 In the Prepare panel, click Mesh Settings . The settings dialog box displays.

2 Toward the bottom of the Common Settings section, click the check

box for Create Curved Mesh Elements.

3 If Use part based measure for Assembly mesh is unchecked, check

the option.

This option is useful when you need a higher mesh resolution in smaller parts. It generally leads to larger number of elements for the overall assembly.

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Before starting the simulation, we can view the mesh. In the Prepare panel,

click Mesh View . Alternatively, in the browser, right-click the Mesh folder to access the command.

Run the Simulation

Now, we will run the simulation.

1 In the Solve panel, click the Simulate command. The Simulate dialog box displays.

If there are any preprocess related messages, they are presented in the expanded section of the dialog box. Click the More command (>>) to expand the dialog box.

2 When ready, click Run, the Simulation progress displays in the dialog

box. Wait for the simulation to finish.

You can run more than one simulation at a time. Multi-select the simulation nodes in the browser, right-click, and click Simulate. The results are displayed within the Results folder of each simulation.

View and Interpret the Results

After the simulation finishes, the Results folder is populated with the simulation results and the graphics region updates to display a results plot.

1 Expand the Results folder. By default, the Von Mises Stress plot

displays.

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2 In the browser, the current result plot has a check mark by the node

icon. To activate other plots, double-click the particular plot node you are interested in seeing. The display updates to present that plot. Now you can perform post-processing tasks. For example, viewing the results with smooth shading or contour plots.

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2 Using the view commands, reorient the model so you can see the

maximum value area.

3 If the maximum value location is obscured by other components, you

can hide those components. In the browser, right-click the components and click Visibility.

Maximum values can be also shown in the Parametric Table for summary and comparison with other simulations. In this case, we will add a Design Constraint, maximum result value, for the assembly.

1 In the Manage panel, click Parametric Table .

2 In a table cell, right-click and click Add Design Constraint. The Select

Design Constraint dialog box displays.

3 Click Von Mises Stress. 4 Click OK.

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We have concluded the first simulation. The second simulation uses most of the items defined in this first simulation. The simulation study will be duplicated and modified as required for the additional study.

Copy and Modify Simulation

The second simulation uses the same analysis as the first simulation. In addition, a local mesh refinement is defined to improve the stress results. We will create a copy of the first Simulation Study and edit the copy to define the second analysis.

1 Right-click the Simulation Study (Separation Contact) node at the

top of the browser and click Copy Simulation. The new simulation is automatically activated.

2 Right-click the newly created Simulation Study browser node and click

the Edit Simulation Properties. The properties dialog box displays.

3 Change the simulation Name to Local mesh refinement. 4 Click OK.

Specify Local Mesh Controls

Next, we define the local mesh refinement.

1 Activate Mesh View and orient the model as shown. 2 Right-click the Mesh folder, and click Local Mesh Control.

3 Select the corner blend face, and enter 0.5 mm for the Element Size

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4 Click OK.

5 To preview the mesh, right-click the Mesh folder and click Update Mesh.

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The mesh preview shows a much finer mesh at the corner blend face compared to the mesh from the first simulation.

Run the Simulation Again

After making the previous modifications, run the Simulate command using the right-click menu or the command from the ribbon.

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2 Click Run. The Simulation progress is reported in the dialog box. 3 Click OK.

View and Interpret the Results Again

Again, the Results folder is populated with the results.

1 Expand the Results node. By default, the Von Mises Stress plot displays. 2 In the Display panel, click Show Maximum Result to display the location of the maximum result. Hide components, as needed, to see the exact location.

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Maximum result values can be also shown in the Parametric Table for summary and comparison with other simulations. In this case, we will add a local constraint (maximum result value for a specific assembly component)

1 In the Manage panel, click the Parametric Table command.

2 Right-click on a cell in the table, and click Add Design Constraint. 3 Click Von Mises Stress

4 Close the parametric table.

To compare result values in the Parametric table, simply check the corresponding boxes in the other simulation studies.

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Summary

In this tutorial, you created two simulations. In completing each simulation, you learned how to:

■ Copy an existing simulation to make new ones.

■ Define manual Contacts.

■ Modify automatic contacts.

■ Add local mesh controls.

■ Display design constraints in the parametric table.

■ Use multi-select to change component visibility.

■ Use Copy / Paste for material overrides.

What Next? As a next step, consider completing the following tutorials:

■ Part Modal and Stress Analysis

■ Assembly Modal Analysis

Previous (page 57)

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Assembly Modal Analysis

4

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About this tutorial

Perform a structural frequency (modal analysis) study to find natural mode shapes and frequencies of vibration.

Simulation Category 30 minutes Time Required Suspension-Fork_Complete.iam Tutorial Files Used

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The tutorial uses an Inventor assembly. It demonstrates the process to create, solve and view results using 3D plots to illustrate the various mode shapes and corresponding frequency values.

Manual contacts and selection of advanced meshing settings are included. The first 10 mode shapes are found and the results are explained.

Objectives

■ Create a new modal simulation.

■ Use Manual Contacts to establish the correct relationship between components.

■ Exclude components, or use a Design View Representation to remove components from the simulation.

■ Override materials.

■ Add constraints.

■ Manually add contacts.

■ Specify mesh parameters.

■ Run the simulation.

■ View the results.

Prerequisites

■ Complete the Assembly Stress Analysis & Contacts and Mesh

Refinement tutorials.

Navigation Tips

Next (page 64)

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Open the Assembly

1 Check to see that the project file is set to Tutorial_Files.ipj.

2 Click the Open command, and navigate to the Assembly FEA 3 folder. 3 Click on Suspension-Fork_Complete.iam, and click Open.

Alternatively, double-click the .iam file.

4 Use Save As to save the model to a new name, such as

Suspension-Fork_Stress.iam. It is not necessary to say Yes to all

components.

5 In the model browser, expand the Representations folder and then

the Level of Detail folder.

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7 In the browser, right-click and clear the check mark next to Suppress

for the following components:

■ Fork-Crown:1

■ Fork-Slider:1

■ Fork-Tube:1

■ Fork-Slider_MIR:1

■ Fork-Tube_MIR:1

8 Right-click the Level of Detail folder node, and click New Level of Detail.

9 Rename the new representation to Stress LOD. 10 Save the assembly model.

We made this level of detail representation to take advantage of the stress analysis environments use of representations.

Create a Simulation Study

To create a simulation you must switch to the Stress Analysis Environment, then you can begin to define the simulation.

1 On the ribbon, click Environments tab ➤ Begin panel ➤ Stress Analysis.

This action takes you into the stress analysis environment.

2 Click on the Create Simulation command. The Create New Simulation dialog box displays.

3 For the Simulation Name, specify Mode Shapes. 4 Leave the Design Objective set to Single Point. 5 For Simulation Type, select Modal Analysis. 6 Enter 10 for the number of modes.

7 Check the Enhanced Accuracy option. The remaining parameters use

default settings.

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8 On the Model State tab, for Level of Detail, select Stress LOD. Note

that it may already be active.

9 Click OK. A new Simulation Study is created and populates the browser

with simulation-related folders.

Exclude Components

In any assembly, there can be components and part features that are not affected by the forces acting on the assembly or have no bearing on the outcome of applying the forces.

For these reasons, and to help the simulation solve faster, it is good to exclude those parts when simulating an assembly response. For a single part simulation, you consider suppressing specific model features.

For an assembly analysis, you use the component context menu option

Exclude From Simulation. Exclusion is different from suppression, which

is what is done when you use a Level of Detail representation. If you think you plan to use the component at a later date in the same simulation, then use the Exclude From Simulation. If you know you will not refer to it later, then you can use a Level of Detail representation.

Because we purposely defined an Assembly Level of Detail representation for this stress analysis simulation, we do not need to exclude several parts. We simply specify that the simulation will use that representation.

NOTE In most cases, this is the optimum way to lower the component count.

If you do not specify the Level of detail representation when first creating the simulation, then you can use the following steps to make use of it.

1 Right-click the Simulation browser node, and click Edit Simulation Properties.

2 Click the dialog box Model State tab.

3 For Level of Detail input, click the drop-down list and select Stress LOD.

4 Click OK. The assembly updates to represent the requested level of detail.

This workflow illustrates how advanced planning, wherever possible, can reduce the effort needed in other phases of your design project.

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Assign Materials

Next, you define the component materials. Not all Autodesk Inventor materials are suited to analysis, so it is necessary to define materials completely in advance, or select from the materials that are defined.

If you want to modify materials, use the Materials and Appearances tools. Modifying materials is not part of this tutorial.

1 On the ribbon, click Stress Analysis tab ➤ Material panel ➤ Assign

.

The dialog box displays.

2 In the Override Materials column, click the cell for the first

component. It activates the materials list within the cell.

3 Click the down arrow to display the drop-down list, and click Titanium. 4 Right-click the cell, and select Copy.

5 Multi-select the other component cells of the Override Material

column, right-click, and select Paste.

6 Click OK to accept the changes and close the dialog box.

The Material browser node is populated with a material node containing a node for each component assigned that material override.

Add Constraints

Using constraints, we specify the boundary conditions for this simulation.

1 In the Constraints panel, click Fixed Constraint. The dialog box

displays with the Selector command active and ready for use.

2 Choose the Fork-Crown face as shown in the following image.

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3 Click OK.

Create Manual Contacts

To define contacts, we must do two things. First, we must have the software automatically detect contacts that meet the default criteria found in the Stress Analysis Settings. Second, we must manually define additional contacts. Manual contacts, consisting of pairs of faces, are used for cases in which the initial default contact tolerance is too small.

The default contact type is bonded; however, you can also assign various contact types such as Separation, Sliding/no Separation, and so on. In this example, we add a manual bonded contact to model the relative displacement of the fork elements.

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Since you have not already run an automatic detection of contacts, you will receive a message that automatic detection will be run before manual contacts can be added.

2 Click OK.

Automatic contacts detect contacts within the default tolerance. Qualified contacts populate the Contacts folder. Once automatic contacts have been established, the Manual Contacts dialog box displays.

To see the automatically created contacts, expand the Contacts folder in the browser.

3 When the Manual Contacts dialog box appears, select the outer surface

of Fork-Tube.ipt and the main interior surface of the Fork-Slider.ipt components. The contact type should be Bonded. Click Apply.

4 Check to see if a contact was made between the Fork-Tube_MIR.ipt

and the main interior surface of the Fork-Slider_MIR.ipt components. The contact type should be Bonded. If not, create the contact with these components using the method from step 3.

5 One more manual contact must be added to represent the component

to which the Fork-Sliders are bolted. Select the two opposing faces of the Fork-Slider as shown in the following image. View navigation commands are available to orient the view.

6 Ensure the contact type is Bonded.

7 Click OK. A bonded contact is assigned between the two faces as seen

in the image.

Next, we specify the meshing options.

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Specify Mesh Options

Use the advanced meshing settings to create a mesh that considers this type of curved and long geometry.

1 In the Prepare panel, click Mesh Settings. 2 In the dialog box:

■ Set Average Element Size to 0.05.

■ Check Create Curved Mesh Elements. Use this option to better mesh round areas of the geometry.

■ Ensure that Use part based measure for assembly mesh is checked. This option creates a higher mesh resolution in smaller parts; it usually generates more elements for the overall assembly.

3 Click OK.

Preview Mesh and Run Simulation

Before starting the simulation, we can view the mesh.

1 In the Prepare panel, click Mesh View. Alternatively, you can

right-click the Mesh browser folder and select the command.

The command is a display state command and acts like an on/off switch for the mesh display. Notice that in the upper corner of the graphics window the node and element counts are presented.

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2 In the Solve panel, click the Simulate command and a dialog box

displays.

3 Click Run, the Simulation progress displays in the dialog box.

View and Interpret Results

After the simulation finishes, the graphics window displays the first mode, and the Results browser folder populates with all the simulation results.

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1 Expand the Results folder.

2 Expand the Modal Frequency folder to expose the list of available

Mode Shapes corresponding to each calculated natural frequency. Double-click the frequency of choice to display it.

The color bar shows relative displacement values. The units are not applicable since the mode shapes values are relative (They have no actual physical value at this point)

Now you can perform post-processing tasks using the Display panel commands. These commands are described in Help.

Animate the results

1 In the browser, select a mode shape you want like to see animated. 2 Click the Animate Results command on the Result panel. 3 Specify 10 for the number of steps. Steps are analogous to images for

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5 When finished observing the displacement animation, click OK to exit

the animation playback.

The Animate Results dialog box also has options for displaying the original wireframe with the plot. You can also record the animation to present or retain for records.

Summary

In this tutorial you performed a structural frequency (modal analysis) analysis with the goal of finding natural mode shapes and frequencies of vibration. The steps performed included:

■ Create a modal simulation.

■ Use Manual Contacts to establish the correct relationship between components.

■ Exclude components, or use a Design View Representation to remove components from the simulation.

■ Override materials

■ Add constraints

■ Manually add contacts

■ Specify mesh parameters

■ Run the simulation

■ View the results

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What Next? As a next step, visit http://www.autodesk.com and try some of the Skill Builders for Stress Analysis. Try using some of these learned techniques on your models.

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FEA Assembly

Optimiza-tion

5

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About this tutorial

Optimize an assembly model using the parametric variations provided in Stress Analysis. Simulation Category 30 minutes Time Required Robot Base.iam Tutorial Files Used

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Objectives

Minimize the mass of the structure while keeping displacement and stress within allowable values. Consider safety criteria and profile size changes.

Prerequisites

■ Complete the Part Modal and Stress Analysis tutorial.

■ Familiarize yourself with the ribbon user interface.

Navigation Tips

Next (page 77)

Open the Assembly

1 Click ➤ Open.

2 Set the Project File to Tutorial_Files.ipj.

3 Open Assembly Optimization using FEA ➤ Robot Base.iam. 4 On the ribbon, click Environments tab ➤ Begin panel ➤ Stress

Analysis .

Define the Simulation

1 On the ribbon, Manage panel, click Create Simulation .

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2 In the Create New Simulation dialog box, enter the following:

■ Name: Optimization

■ Design Objective: Parametric Dimension

■ Simulation Type: Static Analysis

3 Click OK. A new simulation is created and the browser is populated with

folders.

Assign Materials

1 On the ribbon bar, Material panel, click Assign Materials .

2 For the base_plate:1 component, click the Override Material drop-down

list and select Steel. Notice that the Safety Factor column shows that Yield Strength is used for safety analysis.

3 Right-click the Override Material cell for base_plate:1 and select Copy.

Multi-select the other Override Material cells, right-click, and select

Paste. Multiple instances of a component change with one paste. Click OK to close the dialog box.

Adding Constraints

Add constraints to denote mechanical and environmental conditions.

1 On the ribbon bar, Constraints panel, click Fixed .

Stress Analysis INVENTOR

Contents

Chapter 1

Part Modal and Stress Analysis . . . . 1

Chapter 2

Assembly Stress Analysis . . . . 23

Chapter 3

Contacts and Mesh Refinement . . . . 39

Chapter 4

Assembly Modal Analysis . . . . 61

Chapter 5

FEA Assembly Optimization . . . . 75

Chapter 6

Stress Analysis Contacts . . . . 93

Chapter 7

Frame Analysis . . . . 117

Chapter 8

Frame Analysis Results . . . . 135

Chapter 9

Frame Analysis Connections . . . . 149

Chapter 10

Modal Type of Frame Analysis . . . . 173

Chapter 12

Dynamic Simulation - Part 2 . . . . 205

Chapter 13

Assembly Motion and Loads . . . . 227

Chapter 14

FEA using Motion Loads . . . . 245

Part Modal and Stress

Analysis

Simulation 1: About this tutorial

1

1

Open the Model for Modal Analysis

Enter the Stress Analysis Environment

Assign Material

Add Constraints

Preview Mesh

Run Simulation

View the Results

Summary

Copy Simulation

Create Parametric Geometry

Include Optimization Criteria

Add Loads

Set Convergence

Run Simulation

View the Results

Summary

Assembly Stress Analysis

About this tutorial

2

23

Get Started

Stress Analysis Environment

Excluding Components

Assign Materials

Add Constraints and Loads

Stress Analysis Settings

Contact Conditions

Generate Meshes

Run the Simulation

View and Interpret the Results

Summary

Contacts and Mesh

Re-finement

About this tutorial

3

Open the Model

Stress Analysis Environment

Create a Simulation

Exclude Components

Assign Materials

Add Constraints and Loads

Define Contact Conditions

Specify and Preview Meshes

Run the Simulation

View and Interpret the Results

Copy and Modify Simulation

Specify Local Mesh Controls