Getting Starte ® Autodesk Inventor Professional 9 Stress Analys
© Copyright 2004 Autodesk, Inc. All Rights Reserved This publication, or parts thereof, may not be reproduced in any form, by any method, for any purpose. AUTODESK, INC. MAKES NO WARRANTY, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, REGARDING THESE MATERIALS AND MAKE SUCH MATERIALS AVAILABLE SOLELY ON AN “AS-IS” BASIS. IN NO EVENT SHALL AUTODESK, INC. BE LIABLE TO ANYONE FOR SPECIAL, COLLATERAL, INCIDENTAL, OR CONSEQUENTI DAMAGES IN CONNECTION WITH OR ARISING OUT OF PURCHASE OR USE OF THESE MATERIALS. THE SOLE AND EXCLUSI LIABILITY TO AUTODESK, INC., REGARDLESS OF THE FORM OF ACTION, SHALL NOT EXCEED THE PURCHASE PRICE OF TH MATERIALS DESCRIBED HEREIN.
Autodesk, Inc. reserves the right to revise and improve its products as it sees fit. This publication describes the state of this product at th time of its publication, and may not reflect the product at all times in the future.
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The following are registered trademarks of Autodesk, Inc., in the USA and/or other countries: 3D Props, 3D Studio, 3D S tudio MAX, 3D Studio VI 3DSurfer, 3ds max, ActiveShapes, ActiveShapes (logo), Actrix, ADI, AEC Authority (logo), AEC-X, Animator Pro, Animator Studio, ATC, AUG AutoCAD, AutoCAD LT, AutoCAD Map, Autodesk, Autodesk Envision, Autodesk Inventor, Autodesk (logo), Autodesk Map, Autodesk MapGuid Autodesk Streamline, Autodesk University (logo), Autodesk View, Autodesk WalkThrough, Autodesk World, AutoLISP, AutoSketch, backdraft, Bipe bringing information down to earth, Buzzsaw, CAD Overlay, Character Studio, Cinepak, Cinepak (logo), cleaner, Codec Central, combustion, Desig Your World, Design Your World (logo), EditDV, Education by Design, gmax, Heidi, HOOPS, Hyperwire, i-drop, Inside Track, IntroDV, Kinetix, lustr MaterialSpec, Mechanical Desktop, NAAUG, ObjectARX, PeopleTracker, Physique, Planix, P owered with Autodesk Technology (logo), ProjectPoin RadioRay, Reactor, Revit, Softdesk, Texture Universe, The AEC Authority, The Auto Architect, VISION*, Visual, Visual Construction, Visual Drainag Visual Hydro, Visual Landscape, Visual Roads, Visual Survey, Visual Toolbox, Visual Tugboat, Visual LISP, Volo, WHIP!, and WHIP! (logo). The following are trademarks of Autodesk, Inc., in the USA and/or other countr ies: AutoCAD Learning Assistance, AutoCAD LT Learning Assistanc AutoCAD Simulator, AutoCAD SQL Extension, AutoCAD SQL Interface, AutoSnap, AutoTrack, Built with ObjectARX (logo), burn, Buzzsaw.co CAiCE, Cinestream, Civil 3D, cleaner central, ClearScale, Colour Warper, Content Explorer, Dancing Baby (image), DesignCenter, Design Docto Designer's Toolkit, DesignProf, DesignServer, Design Web Format, DWF, DWFit, DWG Linking, DXF, Extending the Design Team, GDX D river, gm (logo), gmax ready (logo),Heads-up Design, jobnet, ObjectDBX, onscreen onair online, Plans & Specs, Plasma, PolarSnap, Productstream, Real-tim Roto, Render Queue, Visual Bridge, Visual Syllabus, and Where Design Connects.
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The following are registered trademarks of Autodesk Canada Inc. in the USA and/or Canada, and/or other countries: discreet, fire, flame, flint, fli RT, frost, glass, inferno, MountStone, riot, river, smoke, sparks, stone, stream, vapour, wire. The following are trademarks of Autodesk Canada Inc., in the USA, Canada, and/or other countries: backburner, Multi-Master Editing.
Autodesk Canada Inc. Trademarks
The following are registered trademarks of Autodesk Canada Inc. in the USA and/or Canada, and/or other countries: discreet, fire, flame, flint, fli RT, frost, glass, inferno, MountStone, riot, river, smoke, sparks, stone, stream, vapour, wire. The following are trademarks of Autodesk Canada Inc., in the USA, Canada, and/or other countries: backburner, Multi-Master Editing.
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HTML Help © 1995-2002 Microsoft Corp. All rights reserved. Internet Explorer © 1995-2001 Microsoft Corp. All rights reserved. Windows NetMeeting © 1996-2001 Microsoft Corp. All rights reserved. TList™ 5 Active X control, Bennet-Tec Information Systems. Systems. Typefaces © 1992 BitstreamÆ typeface library. All rights reserved. Visual Basic® and Visual Basic logo (graphic only) © 1987-2001 Microsoft Corp. All rights reserved. Third Party Copyright Notices
2D DCM, CDM, and HLM are trademarks of D-Cubed Ltd. 2D DCM © D-Cubed Ltd. 1989-2004. CDM © D-Cubed Ltd. 199 2004. HLM © D-Cubed Ltd. 1996-2004. ACIS® Copyright © 1989-2001 Spatial Corp. Portions Copyright © 2002-2004 Autodesk, Inc. COPRA MetalBender © 1989-2002 data M Software GmbH. All rights reserved. dBASE is a registered trademark of Ksoft, Inc. Intel® Math Kernel Library, © 1999-2003 Intel Corporation. All Rights Reserved. MD5C.C - RSA Data Security, Inc., MD5 message-digest message-digest algorithm © 1991-1992 Objective Grid © 2002 Stingray Software, a division of Rogue Wave Software, Inc. All rights reserved. RSA Data Security, Inc. Created 1991. All rights reserved. SafeCast™ © 1996-2002 and FLEXlm™ © 1988-2002 Macrovision Corp. All rights reserved. SMLib © 1998-2003 IntegrityWare, Inc., GeomWare, Inc., and Solid Modeling Solutions, Inc. All rights reserved. Typefaces © 1996 Payne Loving Trust. All rights reserved. uuencode/uudecode uuencode/uudecode © 1983 Regents of the University of California. All rights reserved. Wise for Windows Installer © 2002 Wise Solutions, Inc. All rights reserved. Portions of this software are based in part on the work of the Independent JPEG Group. Group. Portions of this software © 1981-2003 Microsoft Corp. Portions of this software © 1992-2002 ITI. TList ActiveX™ control licensed from Bennet-Tec Information Systems. This software contains Macromedia Flash Player software by Macromedia, Inc., © 1995-2002 Macromedia, Inc. All rights reserve Macromedia and Flash are either registered trademarks or trademarks of Macromedia, Inc. All other brand names, product names or trademarks belong to their respective holders.
© Copyright 2004 Autodesk, Inc. All Rights Reserved This publication, or parts thereof, may not be reproduced in any form, by any method, for any purpose. AUTODESK, INC. MAKES NO WARRANTY, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, REGARDING THESE MATERIALS AND MAKE SUCH MATERIALS AVAILABLE SOLELY ON AN “AS-IS” BASIS. IN NO EVENT SHALL AUTODESK, INC. BE LIABLE TO ANYONE FOR SPECIAL, COLLATERAL, INCIDENTAL, OR CONSEQUENTI DAMAGES IN CONNECTION WITH OR ARISING OUT OF PURCHASE OR USE OF THESE MATERIALS. THE SOLE AND EXCLUSI LIABILITY TO AUTODESK, INC., REGARDLESS OF THE FORM OF ACTION, SHALL NOT EXCEED THE PURCHASE PRICE OF TH MATERIALS DESCRIBED HEREIN.
Autodesk, Inc. reserves the right to revise and improve its products as it sees fit. This publication describes the state of this product at th time of its publication, and may not reflect the product at all times in the future.
Autodesk Trademarks
The following are registered trademarks of Autodesk, Inc., in the USA and/or other countries: 3D Props, 3D Studio, 3D S tudio MAX, 3D Studio VI 3DSurfer, 3ds max, ActiveShapes, ActiveShapes (logo), Actrix, ADI, AEC Authority (logo), AEC-X, Animator Pro, Animator Studio, ATC, AUG AutoCAD, AutoCAD LT, AutoCAD Map, Autodesk, Autodesk Envision, Autodesk Inventor, Autodesk (logo), Autodesk Map, Autodesk MapGuid Autodesk Streamline, Autodesk University (logo), Autodesk View, Autodesk WalkThrough, Autodesk World, AutoLISP, AutoSketch, backdraft, Bipe bringing information down to earth, Buzzsaw, CAD Overlay, Character Studio, Cinepak, Cinepak (logo), cleaner, Codec Central, combustion, Desig Your World, Design Your World (logo), EditDV, Education by Design, gmax, Heidi, HOOPS, Hyperwire, i-drop, Inside Track, IntroDV, Kinetix, lustr MaterialSpec, Mechanical Desktop, NAAUG, ObjectARX, PeopleTracker, Physique, Planix, P owered with Autodesk Technology (logo), ProjectPoin RadioRay, Reactor, Revit, Softdesk, Texture Universe, The AEC Authority, The Auto Architect, VISION*, Visual, Visual Construction, Visual Drainag Visual Hydro, Visual Landscape, Visual Roads, Visual Survey, Visual Toolbox, Visual Tugboat, Visual LISP, Volo, WHIP!, and WHIP! (logo). The following are trademarks of Autodesk, Inc., in the USA and/or other countr ies: AutoCAD Learning Assistance, AutoCAD LT Learning Assistanc AutoCAD Simulator, AutoCAD SQL Extension, AutoCAD SQL Interface, AutoSnap, AutoTrack, Built with ObjectARX (logo), burn, Buzzsaw.co CAiCE, Cinestream, Civil 3D, cleaner central, ClearScale, Colour Warper, Content Explorer, Dancing Baby (image), DesignCenter, Design Docto Designer's Toolkit, DesignProf, DesignServer, Design Web Format, DWF, DWFit, DWG Linking, DXF, Extending the Design Team, GDX D river, gm (logo), gmax ready (logo),Heads-up Design, jobnet, ObjectDBX, onscreen onair online, Plans & Specs, Plasma, PolarSnap, Productstream, Real-tim Roto, Render Queue, Visual Bridge, Visual Syllabus, and Where Design Connects.
Autodesk Canada Inc. Trademarks
The following are registered trademarks of Autodesk Canada Inc. in the USA and/or Canada, and/or other countries: discreet, fire, flame, flint, fli RT, frost, glass, inferno, MountStone, riot, river, smoke, sparks, stone, stream, vapour, wire. The following are trademarks of Autodesk Canada Inc., in the USA, Canada, and/or other countries: backburner, Multi-Master Editing.
Autodesk Canada Inc. Trademarks
The following are registered trademarks of Autodesk Canada Inc. in the USA and/or Canada, and/or other countries: discreet, fire, flame, flint, fli RT, frost, glass, inferno, MountStone, riot, river, smoke, sparks, stone, stream, vapour, wire. The following are trademarks of Autodesk Canada Inc., in the USA, Canada, and/or other countries: backburner, Multi-Master Editing.
Third Party Trademarks
HTML Help © 1995-2002 Microsoft Corp. All rights reserved. Internet Explorer © 1995-2001 Microsoft Corp. All rights reserved. Windows NetMeeting © 1996-2001 Microsoft Corp. All rights reserved. TList™ 5 Active X control, Bennet-Tec Information Systems. Systems. Typefaces © 1992 BitstreamÆ typeface library. All rights reserved. Visual Basic® and Visual Basic logo (graphic only) © 1987-2001 Microsoft Corp. All rights reserved. Third Party Copyright Notices
2D DCM, CDM, and HLM are trademarks of D-Cubed Ltd. 2D DCM © D-Cubed Ltd. 1989-2004. CDM © D-Cubed Ltd. 199 2004. HLM © D-Cubed Ltd. 1996-2004. ACIS® Copyright © 1989-2001 Spatial Corp. Portions Copyright © 2002-2004 Autodesk, Inc. COPRA MetalBender © 1989-2002 data M Software GmbH. All rights reserved. dBASE is a registered trademark of Ksoft, Inc. Intel® Math Kernel Library, © 1999-2003 Intel Corporation. All Rights Reserved. MD5C.C - RSA Data Security, Inc., MD5 message-digest message-digest algorithm © 1991-1992 Objective Grid © 2002 Stingray Software, a division of Rogue Wave Software, Inc. All rights reserved. RSA Data Security, Inc. Created 1991. All rights reserved. SafeCast™ © 1996-2002 and FLEXlm™ © 1988-2002 Macrovision Corp. All rights reserved. SMLib © 1998-2003 IntegrityWare, Inc., GeomWare, Inc., and Solid Modeling Solutions, Inc. All rights reserved. Typefaces © 1996 Payne Loving Trust. All rights reserved. uuencode/uudecode uuencode/uudecode © 1983 Regents of the University of California. All rights reserved. Wise for Windows Installer © 2002 Wise Solutions, Inc. All rights reserved. Portions of this software are based in part on the work of the Independent JPEG Group. Group. Portions of this software © 1981-2003 Microsoft Corp. Portions of this software © 1992-2002 ITI. TList ActiveX™ control licensed from Bennet-Tec Information Systems. This software contains Macromedia Flash Player software by Macromedia, Inc., © 1995-2002 Macromedia, Inc. All rights reserve Macromedia and Flash are either registered trademarks or trademarks of Macromedia, Inc. All other brand names, product names or trademarks belong to their respective holders.
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . About Autodesk Autodesk Inventor Professional . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Learning Autodesk Inventor Professional. . . . . . . . . . . . . . . . . . . . . . . . . . . Using Help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Chapter 1
Getting Getting Started Started With Stress Stress Analysis Analysis . . . . . . . . . . . . . . . . . . . . . . . . Using Stress Analysis Tools Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Understanding Understanding the Value of Stress Analysis . . . . . . . . . . . . . . . . . . . . . . . . . Understanding How How Stress Analysis Works . . . . . . . . . . . . . . . . . . . . . . . . . . Analysis Assumptions Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interpreting Results of Stress Analysis. Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter Chapter 2
Analyzing Analyzing Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Working in the the Stress Analysis Environment Environment . . . . . . . . . . . . . . . . . . . . . . . 1 Running Stress Stress Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Verifying Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Applying Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Applying Constraints Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Setting Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Setting Solution Options Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Obtaining Solutions Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Running Modal Modal Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Chapter Chapter 3
Viewing Viewing Results. Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Using Results Visualization Visualization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Editing the Color Bar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Reading Stress Analysis Analysis Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Interpreting Results Contours. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Setting Results Display Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Chapter Chapter 4
Revising Revising Models and Stress Stress Analyse Analysess . . . . . . . . . . . . . . . . . . . . . . . 31 Changing Model Model Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 Changing Solution Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 Updating Results of Stress Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Chapter Chapter 5
Generatin Generating g Reports. Reports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Running Reports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 Interpreting Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 Scenario. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 Saving and Distributing Distributing Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 Saving Reports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 Printing Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 Distributing Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Chapter Chapter 6
Managing Managing Stress Stress Analysis Analysis Files Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Creating and Using Analysis Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42 Understanding File Relationships. . . . . . . . . . . . . . . . . . . . . . . . . . . .42 Repairing Disassociated Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 Copying Geometry Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 . 43 Resolving File Link Failures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 Creating New Analysis Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44 Exporting Analysis Analysis Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
i
Introduction
In This Chapter
Autodesk Inventor® Professional software provides a combination of industry-specific tools that extend the capabilities of Autodesk Inventor® for completing complex machinery and other product designs. This chapter provides basic information to help you get started using Autodesk Inventor Professional Stress Analysis. Subsequent Subsequent chapters provide descriptions of the Autodesk Inventor Professional work features and functionality.
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Introduction
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Learning Autodesk Invent Professional
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Using Help
About Autodesk Inventor Professional Built on the Autodesk Inventor application, Autodesk Inventor Professional includes several different modules. The module included in this manual is Stress Analysis. It provides functionality for stressing and analyzing mechanical product designs. This manual provides basic conceptual information to help get you started and specific examples that introduce you to the capabilities of Autodesk Inventor Professional stress analysis.
Learning Autodesk Inventor Professional It is assumed that you have a working knowledge of the Autodesk Inventor interface and tools. If you do not, use the integrated Design Support System (DSS) for access to online documentation and tutorials, and complete the exercises in the Autodesk Inventor Getting Started manual. At a minimum, it is recommended that you understand how to: ■
Use the assembly, part modeling, and sketch environments and browsers.
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Edit a component in place.
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Create, constrain, and manipulate work points and work features.
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Set color styles.
It is also recommended that you have a working knowledge of Microsoft® Windows NT® 4.0, Windows® 2000, or Windows® XP, and a working knowledge of concepts for stressing and analyzing mechanical assembly designs.
Using Help As you work, you may need additional information about the task you are performing. The Autodesk Inventor Professional Help system provides detailed concepts, procedures, and reference information about every feature in the Autodesk Inventor Professional modules as well as the standard Autodesk Inventor features.
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To access the Help system, use one of the following methods: ■
Select Help Topics ➤ Autodesk Inventor Professional Help from the standard toolbar, and then click the link to the needed application.
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Press F1 for Help with the active operation.
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In any dialog box, click the ? icon.
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In the graphics window, right-click, and then click How To. The How To topic for the current tool is displayed.
For help on a specific module, scroll to the Autodesk Inventor Professional section at the bottom of the home page for Autodesk Inventor Help, and then click the link to the module of interest.
You can also select options on the main Help home page or click a Help option on the right side of the standard toolbar. For information about new functionality in the most recent release, in Help click the “What’s New in Autodesk Inventor Professional” link, and then click the subject and feature you want to learn about.
4
Getting Started With Stress Analysis
In This Chapter
Autodesk Inventor® Professional Stress Analysis is an add-on to the Autodesk Inventor® part and sheet metal environments. It provides the capability to analyze the stress and frequency responses of mechanical part designs. This chapter provides basic information about the stress analysis environment and the workflow processes necessary to analyze loads and constraints placed on a part.
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Introduction
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Why analyze for stress
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What is stress analysis
Using Stress Analysis Tools Autodesk Inventor Professional Stress Analysis provides tools for determining structural design performance directly on your Autodesk Inventor model. AIP Stress Analysis includes tools to place loads and constraints on a part and calculate the resulting stress, deformation, safety factor, and resonant frequency modes. Enter the stress analysis environment in Autodesk Inventor with an active part. With the stress analysis tools you can:
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Perform a stress or frequency analysis of a part.
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Apply a force, pressure, bearing, moment, or body load to vertices, faces, or edges of the part.
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Apply fixed or non-zero displacement constraints to the model.
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Evaluate the impact of multiple parametric design changes.
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View the analysis results in terms of equivalent stress, deformation, safety factor, or resonant frequency modes.
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Add features such as gussets, fillets or ribs, re-evaluate the design, and update the solution.
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Generate a complete and automatic engineering design report that can be saved to HTML format.
Understanding the Value of Stress Analysis Performing an analysis of a mechanical part in the design phase can help you bring a better product to market in less time. AIP Stress Analysis helps you: ■
Determine if the part is strong enough to withstand expected loads or vibrations without breaking or deforming inappropriately.
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Gain valuable insight at an early stage when the cost of redesign is small.
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Determine if the part can be redesigned in a more cost-effective manner and still perform satisfactorily under expected use.
Stress analysis, for this discussion, is a tool to better understand how a design will perform under certain conditions. It might take a highly trained specialist a great deal of time performing what is often called a detailed analysis to obtain an exact answer with regard to reality . What is often as useful to help predict and improve a design is the trending and behavioral information obtained from a basic or fundamental analysis. Performing this basic analysis early in the design phase can substantially improve the overall engineering process. Here is an example of stress analysis use: When designing bracketry or single piece weldments, the deformation of your part may greatly affect the alignment of critical components causing forces that induce accelerated wear. When evaluating vibration effects, geometry plays a critical role in the resonant frequency of a part. Avoiding or, in some cases, targeting critical resonant frequencies literally is the difference between part failure and expected part performance. For any analysis, detailed or fundamental, it is vital to keep in mind the nature of approximations, study the results, and test the final design. Proper use of stress analysis greatly reduces the number of physical tests required. You can experiment on a wider variety of design options and improve the end product. To learn more about the capabilities of AIP Stress Analysis, view online demonstrations and tutorials, or see how to run analysis on Autodesk Inventor assemblies, visit http://www.ansys.com/autodesk .
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Understanding How Stress Analysis Works Stress analysis is done using a mathematical representation of a physical system composed of: ■
A part (model).
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Material properties.
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Applicable boundary conditions, referred to as preprocessing.
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The solution of that mathematical representation (solving). To find a solution, the part is divided into a number of smaller elements. The solver adds up the individual behaviors of each element to predict the behavior of the entire physical system.
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The study of results of that solution, referred to as post-processing.
Analysis Assumptions The stress analysis provided by Autodesk Inventor Professional is appropriate only for linear material properties where the stress is directly proportional to the strain in the material (meaning no permanent yielding of the material). Linear behavior results when the slope of the material stress-strain curve in the elastic region (measured as the Modulus of Elasticity) is constant. The total deformation is assumed to be small in comparison to the part thickness. For example, if studying the deflection of a beam, the calculated displacement must be significantly less than the minimum cross-section of the beam. The results are temperature-independent. The temperature is assumed not to affect the material properties. The CAD representation of the physical model is broken down into small pieces (think of a 3D puzzle). This process is called meshing. The higher the quality of the mesh (collection of elements), the better the mathematical representation of the physical model. By combining the behaviors of each element using simultaneous equations, you can predict the behavior of shapes that would otherwise not be understood using basic closed form calculations found in typical engineering handbooks.
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The following is a block (element) with well-defined mechanical and modal behaviors.
In this example of a simple part, the structural behavior would be difficult to predict solving equations by hand.
Here, the same part is broken into small blocks (meshed into elements), each with well-defined behaviors capable of being summed (solved) and easily interpreted (post-processed).
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Interpreting Results of Stress Analysis The output of a mathematical solver is generally a very substantial quantity of raw data. This quantity of raw data would normally be difficult and tedious to interpret without the data sorting and graphical representation traditionally referred to as post-processing. Post-processing is used to create graphical displays that show the distribution of stresses, deformations, and other aspects of the model. Interpretation of these post-processed results is the key to identifying: ■
Areas of potential concern as in weak areas in a model.
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Areas of material waste as in areas of the model bearing little or no load.
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Valuable information about other model performance characteristics, such as vibration, that otherwise would not be known until a physical model is built and tested (prototyped).
The results interpretation phase is where the most critical thinking must take place. You compare the results (such as the numbers versus color contours, movements) with what is expected. It is up to you to determine if the results make sense, and to explain the results based on engineering principles. If the results are other than expected, you must evaluate the analysis conditions and determine what is causing the discrepancy.
Equivalent Stress Three dimensional stresses and strains build up in many directions. A common way to express these multidirectional stresses is to summarize them into an Equivalent stress, also known as the von-Mises stress. A threedimensional solid has six stress components. If material properties are found experimentally by a uniaxial stress test, then the real stress system is related to this by combining the six stress components to a single equivalent stress.
Deformation Deformation is the amount of stretching that an object undergoes due to the loading. Use the deformation results to determine where and how much a part will bend, and how much force is required to make it bend a particular distance.
1
Safety Factor All objects have a stress limit depending on the material used, which is referred to as material yield. If steel has a yield limit of 40,000 psi, any stresses above this limit result in some form of permanent deformation. If a design is not supposed to permanently deform by going beyond yield (most cases), then the maximum allowable stress in this case is 40,000 psi. A factor of safety can be calculated as the ratio of the maximum allowable stress to the equivalent stress (von-Mises) and must be over 1 for the design to be acceptable. (Below 1 means there will be some permanent deformation.) Factor of safety results immediately point out areas of potential yield, where equivalent stress results always show red in the highest area of stress, regardless of how high or low the value. Since a factor of safety of 1 means the material is essentially at yield, most designers strive for a safety factor of between 2 to 4 based on the highest expected load scenario. Unless the maximum expected load is frequently repeated, the fact that some areas of the design go into yield does not always mean the part will fail. Repeated high load may result in a fatigue failure, which is not simulated by AIP Stress Analysis. Always, use engineering principles to evaluate the situation.
Frequency Modes Vibration analysis is used to test a model for: ■
Its natural resonant frequencies (for example, a rattling muffler during idle conditions, or other failures)
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Random vibrations
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Shock
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Impact
Each of these incidences may act on the natural frequency of the model, which, in turn, may cause resonance and subsequent failure. The mode shape is the displacement shape that the model adopts when it is excited at a resonant frequency.
1
Analyzing Models
In This Chapter
Once your model is defined, define the loads and constraints for the condition you want to test, and then perform an analysis of the model. Use the stress analysis environment to completely prepare your model for analysis, and then run the analysis. This chapter tells you how to define loads, constraints, and parameters, and run your analysis.
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Stress analysis environme
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Stress analysis interface
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Preparing models for anal
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Running analyses
Working in the Stress Analysis Environment Use the stress analysis environment to analyze your part design and evaluate different options quickly. You can analyze a part model under different conditions using various materials, loads, and constraints (or boundary conditions), and then view the results. You have a choice of performing a stress analysis, or a resonant frequency analysis with associated mode shapes. After viewing and evaluating the results, you can make changes to your model and rerun the analysis to see what effect your changes produced. You can perform an analysis from the part or sheet metal environments. To enter the stress analysis environment 1 Start with the part or sheet metal environment active. 2 At the top of the Features panel bar, Select Stress Analysis from the dropdown menu.
Stress analysis tools are added to the standard toolbar, and some part modeling tools are removed from the toolbar. Stress analysis tools are displayed in the panel bar, and the stress analysis browser is displayed.
Stress Analysis panel bar
Stress Analysis browser
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Stress Analysis tools
Loads and constraints are listed under Loads & Constraints in the browser. If you right-click a load or constraint in the browser, you can: ■
Edit the item. The dialog box for that item opens so that you can make changes.
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Delete the item.
To rename an item in the browser, click it, enter a new name, and then press ENTER.
Running Stress Analysis Once you build or load a part, you can run an analysis to evaluate it for its intended use. You can perform either a stress analysis or a resonant frequency analysis of your part under defined conditions. Use the same workflow steps in either analysis. The following are the basic steps to perform a stress or resonant frequency analysis on a part design. Workflow overview:
Perform a typical analysis
1 Enter the stress analysis environment. 2 Verify that the material used for the part is suitable, or select one. 3 In the stress analysis panel bar, select the type of load you want to apply. The choices are Force, Pressure, Bearing Load, Moment, Body Load or Fixed Constraint. 4 On the model, select the faces, edges, or vertices where you want to apply the load. 5 Enter the load parameters (for example, in the Force dialog box, enter the magnitude and direction). Numerical parameters can be entered as numbers or equations that contain user-defined parameters. 6 Repeat steps 3 through 5 for each load on the part. 7 Apply constraints to the model. 8 Change stress analysis environment settings as needed. 9 Modify or add parameters as needed. 10 Start the analysis. 11 View the results. 12 Change the model and reanalyze it until you simulate the appropriate behavior.
Verifying Material The first step is to verify that your model material is appropriate for stress analysis. When you select Stress Analysis, Autodesk Inventor® checks the material defined for your part. If the material is suitable, it is listed in the stress analysis browser. If it is not suitable, a dialog box is displayed so that you can select a new material.
You can cancel this dialog box and continue setting up your stress analysis. However, when you attempt a stress analysis update, this dialog box is displayed so you can select a valid material before running the analysis. If the yield strength is zero, you can perform the analysis, but the Safety Factor calculation and display are unavailable. If the density is zero, you can perform a stress analysis, but cannot do a resonant frequency (modal) analysis. Once you select a suitable material, click OK.
Applying Loads The first step in preparing your model for analysis is applying one or more loads to the model.
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Workflow overview:
Apply loads for analysis
1 Select the type of load you want to apply. 2 Select the geometry of the model where the load will be applied. 3 Enter the required information for that load.
You can apply as many loads as you need. As you apply them, the loads are listed in the browser under Loads & Constraints. Once you define a load, you can edit it by right-clicking it, and then selecting Edit from the menu. To select and apply a load 1 In the stress analysis environment, choose a load from the list in the Stress Analysis panel bar.
2 For this example, we use Force as the load. After you select Force, you define the force in the Force dialog box.
3 Click faces, edges, or vertices on the part to select them. Use Ctrl-click to remove a feature from the selection set. Once you select an initial feature, your selection is limited to features of the same type (only faces, only edges, only vertices). The location arrow turns white.
4 Click the direction arrow to set the direction of the force. You can set the direction normal to a face or work plane, or along an edge or work axis.
When the force location is a single face, the direction is automatically set to the normal of the face, with the force pointing to the outside of the part 5 To reverse the direction of the force, click the Flip Direction button.
6 Enter the magnitude of the force. To specify the force components, click the More button to expand the dialog box, and then select the check box for Use Components. Enter either a numerical force value or an equation using defined parameters. The default value is 100 in the unit system defined for the part.
7 Click OK. An arrow is displayed on the model indicating the direction and location of the force.
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You follow a similar procedure for each of the different load types. This table summarizes information about each load type: Load
Load-Specific Information
Force
Force can be applied to a set of faces, edges, or vertices. When the force location is a face, the direction is automatically set to the normal of the face, with the force pointing to the inside of the part. Direction can be defined by planar faces, straight edges, two vertices, and axes.
Pressure
Pressure is uniform and acts normal to the surface at all locations on the surface. Pressure is only applied to faces.
Bearing Load
You can only apply the load to cylindrical faces. By default, the applied load is along the axis of the cylinder. Direction of the load can be planar or edge.
Moment
Moment may only be applied to faces. Direction can be defined by planar faces, straight edges, two vertices, and axes.
Body Loads
You must select a direction from the Earth Standard Gravity list to apply gravity. Select the Enable check box under Acceleration or Rotational Velocity. You can only apply one body load per analysis.
Non-zero Displacement
You can used the non-zero displacement feature of the Fixed Constraint as a load. Apply a constraint and check the Use Components check box as described in the next section.
Applying Constraints After you define your loads, you must specify the constraints on the geometry of the part. You can apply as many constraints as you need. The defined constraints are listed in the browser under Loads & Constraints. After you define a constraint, you can edit it by right-clicking it, and then selecting Edit from the menu.
To select and apply a constraint 1 In the Stress Analysis panel bar, click Fixed Constraint. 2 In the graphics window, select a set of faces, edges or vertices to constrain. The location arrow turns white. 3 Click the More button to specify a fixed displacement for the constraint, if needed. Check Use Components, and then check the box next to the global axis label (X, Y, or Z) along which the displacement occurs. You can use parameters and negative values. Use Components to specify a non-zero displacement that can be used as a load.
4 Click OK.
Setting Parameters When you define loads and constraints for a part, the values you enter (magnitudes, vector components, and so on) are stored as parameters in Autodesk Inventor. The parameter names are automatically generated by Autodesk Inventor. For example, load parameters are labeled vn, where v0 is the first load created, v1 the second load, and so on.
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Load magnitude and constraint displacement values can be entered as equations when you are defining them. Or, after defining the loads and constraints, select Parameters from the stress analysis panel bar, and in the Parameters dialog box, enter equations for any of the load or constraint parameters.
You can define and edit parameters at any time, either during part modeling, analysis setup, or post-processing. If you change the parameters associated with a load or constraint after a solution is obtained, the Update command is enabled so you can run a new solution. You cannot delete the system-generated parameters, although they are deleted automatically if their associated loads or constraints are deleted. You also cannot delete parameters that are currently used by a system-generated parameter.
Setting Solution Options Before starting your solution, you can set the analysis type and mesh relevance for the analysis, and then specify whether a new analysis file should be created. Select Stress Analysis Settings from the stress analysis panel bar to open the dialog box. When you finish setting the options, click OK to commit them.
Setting Analyses Types Before starting your solution, in the Settings dialog box, in Analysis Type, select Stress Analysis. Select Both if you want to run a stress analysis and a prestressed modal analysis of your part.
Setting Mesh Relevance In the Settings dialog box, move the slider to set the size of your mesh. The default value of zero is an average mesh. Setting the slider to 100 causes a fine mesh to be used, which gives you a highly accurate result, but causes the solution to take a longer time. Setting the slider to -100 gives you a coarse mesh, which solves quickly, but may contain significant inaccuracies. You can see the mesh that will be used at a particular setting by clicking Preview Mesh.
Specifying New Analysis File There may be times when the analysis file is missing from a part that you or someone else has previously analyzed. This can occur if someone sends you a part but not the analysis file, or if the analysis file for the part is accidentally deleted. To create a new analysis file for the part, click New Analysis File. For more information about running an analysis with missing files or files that do not correspond, see “Resolving File Link Failures” on page 43.
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Obtaining Solutions After you complete all the required steps, the Stress Analysis Update command in the stress analysis panel bar is active. Select it to start the solution. The Solutions Status dialog box is displayed while the solution is in progress. During the solution, Autodesk Inventor is unavailable. Once the solution finishes, the results are displayed graphically. For information about reviewing the results of your solution, see chapter 3, “Viewing Results” on page 25.
Running Modal Analysis In addition to the stress analysis, you can perform a resonant frequency (modal) analysis to find the frequencies at which your part will vibrate, and the mode shapes at those frequencies. Like stress analysis, modal analysis is available in the stress analysis environment. You can do a resonant frequency analysis independent of a stress analysis. You can do a frequency analysis on a prestressed structure, in which case you can define loads on the part before the analysis. You can also find the resonant frequencies of an unconstrained part. Your initial steps must be the same as for stress analysis. Refer to the instructions in “Running Stress Analysis” on page 15 to set up your loads, constraints, parameters, and solution options.
Workflow overview:
Run a modal analysis
1 Enter the stress analysis environment. 2 Verify that the material used for the part is suitable, or select one. 3 Apply any loads (optional). 4 Apply the necessary constraints (optional). 5 Before starting the solution, in the Settings dialog box, Analysis Type section, select Modal Analysis.
Selecting Both runs a stress analysis and a modal analysis of your part. Selecting a modal analysis with a load applied produces a prestressed modal solution. 6 Click OK.
The results for the first six frequency modes are inserted under the Modes folder in the browser. For an unconstrained part, the first six frequencies are essentially zero. 7 To change the number of frequencies displayed or limit the range of frequency results returned, right click the Modes folder, and then select Options.
The Frequency Options dialog box is displayed. Enter the maximum number of modes to find, or the range of frequencies to which you want to limit the results set.
After you complete all the required steps, the Stress Analysis Update command in the stress analysis panel bar is active. 8 Select Stress Analysis Update to start the solution.
The Solutions Status dialog box is displayed while the solution is in progress. Once the solution finishes, the results are available for viewing. The next chapter discusses reviewing the results of the solution.
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Viewing Results
In This Chapter
After analyzing your model under the stress analysis conditions that you defined, you can visually observe the results of the solution. This chapter describes the how to interpret the visual results of your stress analyses.
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Results visualization
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Working with the color b
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Setting results display opti
Using Results Visualization Use results visualization to see how your part responds to the loads and constraints you apply to it. You can visualize the magnitude of the stresses that occur throughout the part, the deformation of the part, the stress safety factor, and for modal analysis, the resonant frequency modes. To enter results visualization 1 Start in the stress analysis environment. Open a part or sheet metal part that has been analyzed, or complete the required steps in your current analysis. 2 In the Stress Analysis panel bar, click Stress Analysis Update.
The color bar is displayed in the graphics window. Post-processing commands are enabled in the standard toolbar, and the display mode shifts to stepped contours.
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To view the different results sets, double-click them in the browser. While viewing the results, you can: ■
Change the color bar to emphasize the stress levels that are of concern to you.
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Compare the results to the undeformed geometry.
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View the mesh used for the solution.
Use the normal view controls to manipulate the model for a threedimensional view of the results. To change any model parameters, you must return to part modeling, and then return to stress analysis and update the solution.
Editing the Color Bar The color bar shows you how the contour colors correspond to the stress values or displacements calculated in the solution. You can edit the color bar to set up the color contours so that the stress/displacement is displayed in a way that is meaningful to you. To edit the color bar 1 Select Color Bar from the stress analysis panel bar. If necessary, pull the grip to the right to open the color bar.
By default, the maximum and minimum values shown on the color bar are the maximum and minimum result values from the solution. You can edit the extreme maximum and minimum values, and the values at the edges of the bands.
2 To edit a value, click it, and then edit the value in the text box. Press ENTER to complete the change.
When you edit the extreme values, black lines showing the maximum and minimum result values are added to the color bar if they fall within the edited range. 3 The yellow grips on the left side of the color bar show the maximum and minimum stress values displayed by the contours. Move these grips to change the size of the extreme color zones (outside of the normal contour values) to make the normal color zones more visible within the color bar.
Adjusting these does not change the values of the contour boundaries. These grips are most useful when the extreme maximum and minimum values have been edited. 4 The white grips indicate the maximum and minimum values shown by the contours. Drag the white grips to change their values and rescale the values of the contour boundaries (gray grips). 5 The stress levels are initially divided into nine equivalent sections, with default colors assigned to each section. The gray grips indicate intervals in the range of your solution. If you don’t want as many intervals, click a grip, and then drag it to an adjacent grip.
This eliminates that color band and updates the contours displayed on the model. 6 To change the colors of the contour bands, double-click the band to open the standard Microsoft Windows color palette. Select an appropriate color, and then click OK to apply the color. 7 When the color bar is set up to your satisfaction, click outside the color bar in the graphics window. 8 These color bar settings are retained for this results set. If you do not want to keep the changes you made, reset the color bar.
To reset the color bar to its default settings, right-click the active color bar, and then select Reset to Defaults.
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Reading Stress Analysis Results When the analysis is complete, you see the results of your solution. If you did a stress analysis or specified that both types of analyses be done, you initially see the equivalent stress results set displayed. If your initial analysis is a resonant frequency analysis (without a stress analysis), you see the results set for the first mode. To view a different results set, double-click that results set in the browser pane. The currently viewed results set has a check mark displayed next to it in the browser. You will always see the undeformed wireframe of the part when you are viewing results.
Interpreting Results Contours The contour colors displayed in the results correspond to the value ranges shown in the legend. In most cases, results displayed in red are of most interest, either because of their representation of high stress or high deformation, or a low factor of safety. Each results set gives you different information about the effect of the load on your part.
Equivalent Stress Equivalent stress results use color contours to show you the stresses calculated during the solution for your model. The deformed model is displayed. The color contours correspond to the values defined by the color bar.
Deformation The deformation results show you the deformed shape of your model after the solution. The color contours show you the magnitude of deformation from the original shape. The color contours correspond to the values defined by the color bar.
Safety Factor Safety factor shows you the areas of the model that are likely to fail under load. The color contours correspond to the values defined by the color bar.
Frequency Modes You can view the mode plots for the number of resonant frequencies that you specified in the solution. The modal results appear under the Modes folder in the browser. When you double-click a frequency mode, the mode shape is displayed. The color contours show you the magnitude of deformation from the original shape. The frequency of the mode is shown in the legend. It is also available as a parameter.
Setting Results Display Options While viewing your results, you can use the following commands located in the stress analysis standard toolbar to modify the features of the results display for your model. Maximum
Turns on and off the display of the point of maximum result in the mode.
Minimum
Turns on and off the display of the point of minimum result in the model.
Boundary Condition
Turns on or off the display of the load symbols on the part.
Element Visibility
Displays the element mesh used in the solution in conjunction with the result contours.
Use the Deformation Style menu to change the deformed shape exaggeration. Selecting Actual shows you the deformation to scale. Since the deformations are often small, the various automatic options exaggerate the scale so that the shape of the deformation is more pronounced.
Use the Display Settings menu to set the contour style to stepped, smooth, or no contours. If you turn off the contours, the mesh is displayed for your deformed part. If you have Element Visibility on, the mesh elements are displayed; otherwise, a solid, gray mesh is displayed. The legend is displayed while contours are off. The values of all of the display options for each results set are saved for that results set.
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Revising Models and Stress Analyses
In This Chapter
After you run a solution for your model, you can evaluate how changes to the model or analysis conditions will affect the results of the solution. This chapter tells you how to make changes to solution conditions on the part and rerun the solution.
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Updating part geometry
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Changing solution conditi
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Rerunning analysis
Changing Model Geometry After you run an analysis on your model, you can change the design of your model and rerun the analysis to see the effects of the changes. To edit a design and rerun analysis 1 Return to part modeling by selecting Part Features from the main panel bar menu, or Model from the browser menu.
The part modeling toolbars and browser are displayed, and the graphics window changes back to the solid undeformed part. 2 Click the Last Displayed Stress Result icon to turn on the display of the last results set.
Viewing the results of your solution as you edit the initial geometry can give you an insight as to which dimension to edit to get results closer to your intent. 3 In the browser, select the feature that you want to edit. It is highlighted on the wireframe. 4 In the browser, right-click a sketch for the feature that you want to edit. Select Visibility to make the sketch visible on the model. 5 Double-click the dimension that you want to change, enter the new value in the text box, and then click the green check mark.The sketch is updated. 6 From the panel bar drop-down menu, select Stress Analysis to return to the stress analysis environment. 7 From the panel bar, select Stress Analysis Update to update the geometry and the solution.
After you update the stress analysis, the load symbols are properly relocated if the feature that they were associated with moved as a result of the geometry change. The direction of the load does not change, even if the feature associated with the load changes orientation.
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Changing Solution Conditions After you run an analysis on your model, you can change the conditions under which the solution was obtained and rerun the analysis to see what effects the changes have. At this point, you can edit the loads and constraints you defined, add new loads and constraints, or delete loads and constraints. You can also change the relevance of your mesh or the analysis type. To change your solution conditions, enter the stress analysis environment if you are not already in it. To delete a load or constraint ■
In the browser, right-click a load or constraint, and then select Delete from the menu.
To add a load or constraint ■
In the panel bar, select the command and follow the same procedure you used to create your initial loads and constraints.
To edit a load or constraint 1 In the browser, right-click a load or constraint, and then select Edit from the menu.
The same dialog box you used to create the load or constraint is displayed. The values in the dialog box are the current values for that load or constraint. 2 Click the location arrow on the left side of the dialog box to enable feature picking.
You are initially limited to selecting the same type of feature (face, edge, or vertex) that is currently used for the load or constraint. To remove any of the current features, control-click them. If you remove all of the current features, your new selections can be of any type. 3 Click the white Direction arrow to change the direction of the load. 4 Click the Flip Direction button to reverse the direction, if needed. 5 Change any values associated with the load or constraint. 6 Click OK to apply the load or constraint changes.
To hide a load symbol ■
On the toolbar, click the Boundary Condition display button. The load symbols are hidden.
To redisplay a load symbol ■
On the toolbar, click the Boundary Condition display button again. The load symbols are redisplayed.
To temporarily display load symbols ■
In the browser, pause the cursor over the Loads & Constraints folder or a particular load.
The load symbols are displayed. NOTE If you edit a load while the load symbols are hidden, the symbols for all of the loads are displayed, and remain on after the editing is complete.
To change the mesh relevance 1 In the stress analysis panel bar, select Stress Analysis Settings. 2 In the Settings dialog box, move the slider to set the relevance of your mesh. 3 Click Preview Mesh to view the mesh at a particular setting.
The preview mesh is shown on the undeformed shaded view of your part. To change the analysis type 1 On the stress analysis panel bar, select Stress Analysis Settings. 2 In the Settings dialog box, Analysis Type menu, select the new analysis type.
If you choose Stress Analysis or Modal Analysis, only the results sets for the selected analysis type are displayed in the browser. Any previously obtained results sets are removed.
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Updating Results of Stress Analysis After you change any of the solution conditions, or if you edit the part geometry, the current results are invalid. This is indicated by a lightning bolt symbol on your results icons, and the Stress Analysis Update item becomes active in the panel bar. To update stress analysis results ■
In the stress analysis panel bar, select Stress Analysis Update. New results are generated, based on your revised solution conditions.
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Generating Reports
In This Chapter
Once you run an analysis on a part, you can generate a report that provides you with a written record of the analysis environment and results. This chapter tells you how to generate a report for an analysis and interpret the report, and how to save and distribute the report.
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Generating reports
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Reading reports
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Saving and distributing rep
Running Reports After you run a stress analysis on a part, you can save the details of that analysis for future reference. Use the Report command to save all the analysis conditions and results in HTML format for easy viewing and storage. To generate a report 1 Set up and run an analysis for your part. 2 Set the zoom and view orientation to best illustrate the analysis results. The view you choose is the view used in the report. 3 From the panel bar, select Report to create a report for the current analysis. When it is finished, a browser window containing the report is displayed. 4 Save the report for future reference using the browser Save As command.
Interpreting Reports The report contains a summary, introduction, scenario, and appendices.
Summary The summary contains an overview of the files used for the analysis and the analysis conditions and results.
Introduction The introduction describes the contents of the report and how to use them in interpreting your analysis.
Scenario The scenario gives details about the various analysis conditions.
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Model The model section contains: ■ ■
A description of the physical characteristics of the model A description of the mesh relevance, and number of nodes and elements
Environment The environment section contains: ■
Loading conditions and constraints
Solution ■ ■ ■ ■
Equivalent stress Deformation Safety factor Frequency response results
Appendices Appendices include several sections as follows: Scenario Figures
Labeled figures showing the contours for the different results sets, such as equivalent stress, deformation, safety factor, and mode shapes.
Material Properties
Properties and stress limits for the material used for the analysis.
Glossary
Definitions of terms used in the report.
Distributing This Report
List of the files generated to produce the report, and where they are stored.
Saving and Distributing Reports The report is generated as a set of files that can be viewed in a Web browser. It includes the main HTML page, style sheets, generated figures, and other files listed at the end of the report.
Saving Reports Look at the Distributing This Report section at the end of the report. It contains a table listing of all of the files generated as part of the report. If you want to keep this report for future reference, it is recommended you create a folder in a permanent storage location and move or copy all of the report files to the folder. If you have multiple reports to save, create a separate folder for each report. Use your browser Save As command to save all of the report files into a folder of your choosing. Recent versions of Microsoft Internet Explorer give you the option of opening your report in Microsoft Word. You can then save it as a Word document if you prefer. Be careful when you save a report into a folder where you previously saved a copy of the same report. You may end up with files in the directory that were used by the previous version of the report but are not used by the current version. In order to avoid confusion, it is best to use a new folder for each version of a report, or to delete all of the files in a folder before reusing it.
Printing Reports Use your Web browser Print command to print the report as you would any web page.
Distributing Reports To make the report available from a Web site, move all of the files associated with the report to your Web site, and distribute a URL that points to the main page of the report, the first file listed in the table.
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Managing Stress Analysis Files
In This Chapter
Running a stress analysis in Autodesk Inventor® creates a separate file that contains the stress analysis information. In addition, the part file is modified to indicate the presence of a stress file and the name of the file. This chapter tells you how the files are interdependent, and what should be done if the files become separated.
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Creating stress analysis fil
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Stress analysis and part fil interdependence
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Fixing disassociated files
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Exporting analysis informa to ANSYS WorkBench
Creating and Using Analysis Files You can run a stress analysis by creating a part in Autodesk Inventor, and then setting up your stress analysis conditions. You can also load a part that you previously created, on which you have not yet run a stress analysis, and set up your analysis conditions. Once you set up a stress analysis for a part, when you save the part you also save the stress analysis information for that part. To start a new analysis 1 Load an existing part or create a new part in the part or sheet metal environments. 2 Enter the stress analysis environment by selecting Stress Analysis from the Feature panel bar menu. 3 Set up your analysis conditions.
After you set up any stress analysis information, saving your part also saves the associated stress analysis information in the part file. Stress analysis input and results information, including loads, constraints, and all results, is also saved in a separate file. The stress analysis file has the same name as your part file, but uses the extension .ipa. By default, the .ipa file is stored in the same folder as the .ipt file.
Understanding File Relationships Activating the stress analysis environment, and then saving the .ipt file does not create an .ipa file. You must add at least one condition before Autodesk Inventor creates the .ipa file. The .ipa file contains information that indicates which .ipt file is associated with the .ipa file. Multiple .ipt files cannot reference the same .ipa file, and multiple .ipa files cannot reference the same .ipt file. The Save Copy As command does not generate a new .ipa file. This means that the new .ipt file references the same .ipa file as the old .ipt file. For more information about the Save Copy As command, see “Copying Geometry Files” on page 43. An existing .ipa file is not loaded until the stress analysis environment is activated.
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Repairing Disassociated Files Under certain circumstances, you might edit the part file without the presence of the .ipa file. For example, a consultant might be sent the .ipt file but not the .ipa file. You can edit the part file through the Skip option in the Resolve Link dialog box. If you edit the part while the .ipa file is missing and then try to reassociate the part with its analysis file, Autodesk Inventor makes an attempt to update the stress conditions. There is a possibility that errors may occur, however, when you try to reassociate the files.
Copying Geometry Files You can create a copy of an .ipt file using the Save Copy As command or your operating system file copy command. When this happens, the copy of the .ipt file still references the original .ipa file. If you open the copy of the part, and then activate the stress analysis environment, a dialog box asks if you want to keep the stress analysis information defined for that part. If you click No, the stress analysis information is removed, and the part can be edited as if it never had an analysis performed on it. If you click Yes, Autodesk Inventor creates a copy of the original .ipa file, and changes the references in the copy of the part and the copy of the .ipa file to reference each other.
Resolving File Link Failures In some cases, the .ipa file might fail to resolve when you try to perform an analysis of the part. For example, the user may rename or move the .ipa file, or a vendor may receive a copy of an .ipt file without the associated .ipa file. In these circumstances, the .ipa file fails to resolve and you are prompted with the Resolve Link dialog box. At this point, you can do two things, other than cancel the file open process: ■
Skip the file.
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Select an existing .ipa file.
Skipping Missing IPA Files If you elect to edit a part even though the .ipa file is missing, all stress analysis commands are unavailable except for the Stress Analysis Settings command. You can edit the part document itself. However, you cannot perform any stress analysis work.
Selecting Existing IPA Files If the .ipa file is missing, you can select an existing renamed or moved .ipa file. The next time the associated .ipt file is loaded, you are prompted with the Resolve Link dialog box, and you can browse to the new name or location.
Creating New Analysis Files If you open a part with a missing .ipa file, you can use the Stress Analysis Settings dialog box to create a new .ipa file. If a part is opened and its analysis file is missing, select Stress Analysis Settings. The New Analysis File button becomes available only under these circumstances. To create a new .ipa file, click New Analysis File. Autodesk Inventor attempts to create a new .ipa file in the default location using the default name. If a file already exists using this name and location, Autodesk Inventor checks the .ipa file to see if it points to the active .ipt file. If it does, a dialog box asks if you want to reuse the .ipa file or create a new one. When you create a new file, the new .ipa file has boundary conditions that match those stored in the .ipt file.
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Exporting Analysis Files In some cases, you might need to run a more complex analysis on your part than can be handled by AIP Stress Analysis. You have the option to export your current analysis information to a file that can be imported to ANSYS WorkBench, where a more complex analysis can be performed. To export your information to ANSYS WorkBench 1 After you set up and run an analysis, from the stress analysis panel bar, select Export to ANSYS. 2 Browse to the location where you store your project files. 3 Select Save.
The file is saved using the same name as your part file, with the extension .dsdb. You can now import your part and its analysis file into ANSYS WorkBench to perform more complex analyses.
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Index
A analyses complex, 45 meshing, 8 post processing, 10 reports, 38 rerunning on edited designs, 32 results, reading, 29 solving, 8 types, setting, 22, 34 updating, 35 vibration, 11 workflow, 15 analysis (.ipa) files, 42 exporting, 45 recreating missing, 22, 44 repairing disassociated, 43 analysis results, viewing, 26 ANSYS WorkBench, 45
B bearing loads, 19 body loads, 19 Boundary Condition command, 30 browser, Stress Analysis, 14
C Choose Material dialog box, 16 color bar, 27 constraints browser display, 15 deleting, adding, and editing, 33
constraints ( continued ) fixed displacements, 20 selecting and applying, 19 contour colors, 29
D deformation results, 10, 29 options for displaying, 30 dialog boxes Choose Material., 16 Fixed Constraint, 20 Force, 17 Frequency Options, 24 Parameters, 21 Solutions Status, 23 Stress Analysis Settings, 22
E Element Visibility command, 30 equivalent stress results, 29 equivalent stresses, 10 exercises, prerequisites, 2
F factor of safety results, 11 file type .ipa, 42 files, analysis reassociating, 43 recreating missing, 22 Fixed Constraint dialog box, 20 Force dialog box, 17
force loads, 19 frequency modes, 11 Frequency Options dialog box, 24 frequency results options, 24
post processing analyses, 10 preprocessing, 8 prerequisites for exercises, 2 pressure loads, 19
G
R
geometry, editing, 32
Report command, 38 reports printing and distributing, 40 saving, 38, 40 resonant frequency analyses performing, 23 resonant frequency results, 29 results deformation, 10 display options, 30 equivalent stresses, 10 frequency options, 24 reviewing, 10 safety factor, 11 stress analysis, reading, 29 updating, 35 viewing, 26
H Help systems, 2
L load symbols, 32 displaying, 30, 34 loads browser display, 15 deleting, adding, and editing, 33 parameters, setting, 20 selecting and applying, 16, 17 summary of types, 19
M material, choosing, 16 Maximum command, 30 meshes creating, 8 displaying, 30 size settings, 22, 34 viewing, 27 Minimum command, 30 modal analyses, 11, 23, 24 model geometry, editing, 32 modes frequency, 11 result options, 24 moment loads, 19
N natural resonant frequencies, 11 non-zero displacement loads, 19
O options for solutions, 22
P panel bar, Stress Analysis, 14 Parameters dialog box, 21 parameters, setting for loads, 20
4
S safety factor results, 11, 29 solutions generating, 23 methods, 8 options, setting, 22 Solutions Status dialog box, 23 solutions, rerunning, 33 stress analysis assumptions, 8 environment, 14 functionality, 7 results, 29 tools, 6 workflow, 15 Stress Analysis Settings dialog box, 22 Stress Analysis Update command, 23, 35 stresses, equivalent, 10
T tools, stress analysis, 14 types of analyses, setting, 22
U update analyses, 35 Update command, 23
V
W
vibration frequency analyses, 23 von Mises stress, 10
workflows analyses, performing typical, 15 applying loads for analyses, 17 running modal analyses, 24