ADSK Simulation Mechanical 2013

2013

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II Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012

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Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012 III

© 2012 Autodesk, Inc. All rights reserved.

Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes

Algor

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IV Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012

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Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012 V

TABLE OF CONTENTS

Introduction ................................................ 1

Overview ................................................................................................................................1 Software Installation, Services, and Support .......................................................................1

Installing and Running Autodesk® Simulation Mechanical or Multiphysics ................1 System Requirements ...................................................................................................2 Subscription Center .......................................................................................................4 Web Links ......................................................................................................................4 Tutorials .........................................................................................................................5 Webcasts and Web Courses ........................................................................................5 How to Receive Technical Support...............................................................................5 Updates ..........................................................................................................................6

Background of FEA ...............................................................................................................7 What is Finite Element Analysis? ..................................................................................7 Basic FEA Concepts .....................................................................................................7 How Does Autodesk Simulation Mechanical Work? ................................................. 10 The General Flow of an Analysis in Autodesk Simulation Mechanical .................... 10

Stress and Strain Review .................................................................................................. 11 Equations Used in the Solution .................................................................................. 11 Limits of Static Stress with Linear Material Models ................................................... 12 Mechanical Event Simulation (MES) Overcomes Limitations .................................. 12 Hand-Calculated Example ......................................................................................... 13

Heat Transfer Review ........................................................................................................ 13 Equations Used in the Solution .................................................................................. 13

Linear Dynamics Review ................................................................................................... 14

Chapter 1: Using Autodesk® Simulation Mechanical or

Multiphysics ..................................... 15

Chapter Objectives ............................................................................................................ 15 Navigating the User Interface ............................................................................................ 15

Commands ................................................................................................................. 17 Using the Keyboard and Mouse ................................................................................ 18 Introduction to the View Cube .................................................................................... 19 Additional View Controls ............................................................................................ 20 Legacy View Controls in Autodesk Simulation Mechanical and Multiphysics .......... 22

Steel Yoke Example........................................................................................................... 22 Opening and Meshing the Model ............................................................................... 23 Setting up the Model ................................................................................................... 24 Analyzing the Model ................................................................................................... 28 Reviewing the Results ................................................................................................ 28 Viewing the Displaced Shape .................................................................................... 29 Creating an Animation ................................................................................................ 29 Generating a Report ................................................................................................... 29

Chapter 2: Static Stress Analysis Using CAD Solid Models .... 33

Chapter Objectives ............................................................................................................ 33 Archiving a Model ............................................................................................................... 33 Types of Brick Elements .................................................................................................... 34 Generating Meshes for CAD Models ................................................................................ 35

Creating a Mesh ......................................................................................................... 36 Model Mesh Settings – Options ................................................................................. 37

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Table of Contents

VI Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012

Tips for Modeling with CAD Solid Model Software for FEA ............................................. 39 Simplify CAD Solid Models with Autodesk Fusion ........................................................... 40 Working with Various Unit Systems .................................................................................. 41 Loading Options ................................................................................................................. 43

Load Cases ................................................................................................................. 44 Constraint Options ............................................................................................................. 46

Modeling Symmetry and Antisymmetry ..................................................................... 46 Design Scenarios ............................................................................................................... 47 Load and Constraint Group ............................................................................................... 49 Local Coordinate Systems ................................................................................................ 50 Defining Materials and Using the Material Library Manager ........................................... 51

Adding Material Libraries and Material Properties .................................................... 53 Examples of Loads and Constraints ................................................................................. 55

When to Use Displacement Boundary Elements ...................................................... 55 Using Local Coordinate Systems ............................................................................... 55 Using Surface Variable Loads ................................................................................... 59

Exercise A: Frame – Full to Quarter-Symmetry Model Comparison ...................... 63

Chapter 3: Results Evaluation and Presentation .............. 65

Chapter Objectives ............................................................................................................ 65 Background on How Results are Calculated .................................................................... 65 How to Evaluate Results ................................................................................................... 66

Displacement Results ................................................................................................. 66 Stress Results ............................................................................................................. 68 Reaction Force Results .............................................................................................. 70 Inquiring on the Results at a Node ............................................................................. 70 Graphing the Results .................................................................................................. 71

Presentation Options ......................................................................................................... 73 Contour Plots .............................................................................................................. 73 Image File Creation .................................................................................................... 77 Animating FEA Results .............................................................................................. 78 Using the Configure Report Utility .............................................................................. 79

Exercise B: Yoke – Evaluation of Results and Generation of a Report ................. 81

Chapter 4: Midplane Meshing and Plate Elements .............. 83

Chapter Objectives ............................................................................................................ 83 Meshing Options ................................................................................................................ 83 Element Options ................................................................................................................. 87

Plate Theory and Assumptions .................................................................................. 87 Loading Options ................................................................................................................. 88

Example of Defining the Element Normal Point ........................................................ 89 Result Options .................................................................................................................... 92

Exercise C: Midplane Meshing and Plate Element Orientation .............................. 93

Chapter 5: Meshing .......................................... 95

Chapter Objectives ............................................................................................................ 95 Refinement Options ........................................................................................................... 95

Automatic Refinement Points ..................................................................................... 95 Global Refinement Options ........................................................................................ 97

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Table of Contents

Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012 VII

Creating Joints ................................................................................................................... 99 Creating Bolts ................................................................................................................... 101 Mesh Convergence Testing ............................................................................................ 103

Performing a Mesh Study ......................................................................................... 104

Exercise D: Yoke and Clevis Assembly .................................................................. 105

Chapter 6: Introduction to Contact ......................... 107

Chapter Objectives .......................................................................................................... 107 Uses for Contact .............................................................................................................. 107 Contact Options ............................................................................................................... 107

Setting up Contact Pairs ........................................................................................... 107 Types of Contact ...................................................................................................... 108 Surface Contact Direction ........................................................................................ 111

Contact Example .............................................................................................................. 112 How to Model Shrink Fits: ........................................................................................ 112

Shrink Fit Example ........................................................................................................... 113 Case 1 – Shrink Fit / No Sliding ............................................................................... 114 Case 2 – Shrink Fit / Sliding ..................................................................................... 118

Result Options .................................................................................................................. 118

Exercise E: Yoke Assembly with Contact .............................................................. 119

Chapter 7: Introduction to Linear Dynamics ................. 121

Chapter Objectives .......................................................................................................... 121 Modal Analysis ................................................................................................................. 121 Weight ............................................................................................................................... 122 Load Stiffening ................................................................................................................. 123 Example of Natural Frequency (Modal) Analysis ........................................................... 124

Meshing the Model ................................................................................................... 125 Adding Constraints ................................................................................................... 126 Defining the Materials ............................................................................................... 126 Analyzing the Model ................................................................................................. 126 Reviewing the Results .............................................................................................. 126

Critical Buckling Analysis ................................................................................................. 127 Setting Up a Critical Buckling Analysis .................................................................... 128

Result Options .................................................................................................................. 129 Other Linear Dynamics Analyses .................................................................................... 129

Exercise F: Concrete Platform ................................................................................ 131

Chapter 8: Steady-State Heat Transfer ...................... 133

Chapter Objectives .......................................................................................................... 133 3-D Radiator Example ..................................................................................................... 133

Meshing the Model ................................................................................................... 134 Setting up the Model ................................................................................................. 135 Analyzing the Model ................................................................................................. 136 Reviewing the Results .............................................................................................. 136

Meshing Options .............................................................................................................. 137 Thermal Contact ....................................................................................................... 137

Element Options ............................................................................................................... 139 Rod Elements ........................................................................................................... 139 2-D Elements ............................................................................................................ 139 Plate Elements .......................................................................................................... 140 Brick and Tetrahedral Elements ............................................................................... 141

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Table of Contents

VIII Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012

Loading Options ............................................................................................................... 143

Nodal Loads .............................................................................................................. 143 Surface Loads........................................................................................................... 145 Element Loads .......................................................................................................... 150 Body-to-Body Radiation ........................................................................................... 152 Controlling Nonlinear Iterations ................................................................................ 156

Result Options .................................................................................................................. 157

Exercise G: Infrared Detector Model ....................................................................... 161

Chapter 9: Transient Heat Transfer ......................... 163

Chapter Objectives .......................................................................................................... 163 When to Use Transient Heat Transfer ............................................................................ 163 Element Options ............................................................................................................... 163 Loading Options ............................................................................................................... 164

Load Curves ............................................................................................................. 164 Controlling Nodal and Surface Controlled Temperatures ....................................... 165

Result Options .................................................................................................................. 166

Exercise H: Transistor Case Model ......................................................................... 167

Chapter 10: Thermal Stress ................................. 169

Chapter Objectives .......................................................................................................... 169 Multiphysics Overview ..................................................................................................... 169 Performing a Thermal Stress Analysis ........................................................................... 170

Exercise I: Disk Brake Rotor Heat-up and Stress ................................................ 173

Appendix A – Finite Element Method Using Hand Calculations . 175

Model Description and Governing Equations ................................................................. 177

Hand-Calculation of the Finite Element Solution ............................................................ 179

Autodesk® Simulation Mechanical Example .................................................................. 180

Appendix B – Analysis Types in Autodesk® Simulation

Multiphysics .................................. 183

Background on the Different Analysis Types ................................................................. 185 Choosing the Right Analysis Type for Your Application ................................................ 192 Combining Analysis Types for Multiphysics ................................................................... 196

Appendix C – Material Model Options ........................ 197

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Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012 1

Introduction

Overview

This course will introduce you to the analysis products available within the Autodesk®

Simulation Mechanical software. These capabilities include static stress with linear material

models, heat transfer, and linear dynamics analyses. The course will focus exclusively on

models originating from CAD solid modeling programs. You will learn the various meshing

options available for creating solid and plate elements. The available load and constraint

options for each of the covered analysis types will also be presented. You will learn how to

evaluate the results of the analyses and how to create presentations of the results, including

images, animations and HTML reports. This course is a prerequisite to the more advanced

topic of Mechanic Event Simulation (MES) covered in the Part 2 training seminar.

Software Installation, Services, and Support

Installing and Running Autodesk® Simulation Mechanical or Multiphysics

The simulation software is distributed on DVDs with the exception of software for the Linux

platform, which is distributed on CDs. In addition, the software may be downloaded from the

Autodesk website. When you place the software DVD into a DVD-ROM drive, a launch

dialog box having four options will appear. If you want to set up the software on a client

workstation, whether you will be using a license locked to a single computer or a network

license, press the "Install Products" button. If using a network license, you must already

have the license server software installed on a computer on the network. If you wish to create

pre-configured deployments for installing the product on multiple client workstations, choose

the "Create Deployments" command. If you want to set up the computer as a license server

to control the number of concurrent users through a network, or, if you wish to install optional

reporting tools, press the "Install Tools and Utilities" command. Finally, a fourth command

on the launch screen, "Read the Documentation," leads to a screen from which you can

access a ReadMe file and other installation and licensing guides.

During the product installation process, you will need to specify your name, the name of your

organization. You will also need to enter the product serial number and the product key.

Otherwise, you will be limited to a 30-day trial period. To customize the installation location

on your computer, the components to be installed, and/or to specify a network license server,

you will have to press the "Configuration" button that appears on one of the screens during

the installation process. Then, follow the prompts, provide the required information, and click

the "Configuration Complete" button to continue the installation process.

Any time after the installation, you will be able to start the software by using the available

shortcut found in the "Start" menu folder, "All Programs: Autodesk: Autodesk

Simulation 2013." The version number is included in the start menu folder name and

shortcut. The name of the shortcut will depend upon which package has been purchased

("…Simulation Mechanical "…Simulation Multiphysics"). In the dialog box that appears

when the program is launched, you will be able to open an existing model or begin a new

model. The simulation software will be used to create, analyze, and review the results of an

analysis within a single user interface, regardless of the analysis type.

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Introduction

2 Autodesk® Simulation Mechanical 2013 – Part 1 – Seminar Notes 5/30/2012

System Requirements

We recommend the following system specifications for a Microsoft® Windows® platform

running Autodesk Simulation software. These specifications will allow you to achieve the

best performance for large models and advanced analysis types.

32-Bit 64-Bit *

Dual Core or Dual Processor Intel® 64

or AMD 64, 3 GHz or higher

2 GB RAM or higher (3 GB for MES

and CFD applications)

30 GB of free disk space or higher

256 MB or higher OpenGL accelerated

graphics card

DVD-ROM drive

Dual Core or Dual Processor Intel

64 or AMD 64, 3 GHz or higher

8 GB RAM or higher

100 GB of free disk space or higher

512 MB or higher OpenGL

accelerated graphics card

DVD-ROM drive

Supported Operating Systems:

Microsoft Windows 7 (32-bit and 64-bit editions)

Microsoft Windows Server 2003 and Windows Server 2008

Microsoft Windows XP (32-bit and 64-bit editions)

Linux **

Other Requirements (All Platforms):

Mouse or pointing device

Sound card and speakers ***

Internet connection ***

Web browser with Adobe Flash Player 10 (or higher) plug-in ***

* We recommend usage of a 64-bit version of the operating system to run large models of any

analysis type and for Mechanical Event Simulation, CFD, and Multiphysics analyses.

While a 32-bit machine can be configured for larger system memory sizes, architectural

issues of the operating system limit the benefit of the additional memory.

** Linux may be used as a platform for running the solution phase of the analysis only. It

may be used for a distributed processing (or clustering) platform. However, pre- and

post-processing is done in the graphical user interface, which must be installed and run

on a Microsoft Windows platform.

*** These requirements are due to the use of multimedia in our product line and the

availability of distance learning webcasts, software demos, and related media.

Minimum system requirements and additional recommendations for Linux platforms may be

found on the Autodesk website:

http://usa.autodesk.com/support/system-requirements/

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http://usa.autodesk.com/support/system-requirements/

Introduction


Autodesk Simulation Help

Autodesk Simulation Help is available via Wiki Help. This resource contain the following

information:

Documentation for all of the model creation options within the user interface

Documentation for all of the Autodesk Simulation analysis types

Documentation for all of the result options available within the user interface

Essential Skills videos

Step-by-step examples that illustrate many modeling and analysis options

Meshing, modeling, and analysis tutorials

How to Access the Help Files

Select the "Getting Started" tab. Click on the "Online Wiki Help" command. The

title page of the Autodesk Simulation Help will appear.

You can navigate through the Online Wiki Help via the table of contents to the left or by

using the "Search" or "Index" tabs.

Features of the WIKI Help

Moderated by Autodesk professionals Wiki Help combines our product help with expert

knowledge contributed by our passionate users.

We all learn differently, Autodesk Wiki Help accommodates these differences by

offering content in an array of formats including video instructions and articles. To make

this wide assortment of information available the Wiki help search tool extends beyond

the core Wiki help content, automatically searching the Autodesk support

knowledgebase, discussion forums, blogs and other community sites

Figure I.1: Autodesk Simulation In-Product Help

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Introduction


Search the Help Files using Keywords

All of the pages in the Help files can be searched based on keywords.

The keywords are entered at the top of the "Search" tab on the left side of the Online Wiki

Help screen. Topics that match the search criteria are listed below.

Keywords are used to search the Help files. You may use single or multiple keywords.

Boolean operators (AND, OR, NEAR, and NOT) are available to enhance the search utility.

Also, phrases may be enclosed in quotes to search only for a specific series of words.

Subscription Center

Along with your Autodesk Simulation software purchase, you have the option of purchasing

various levels of Subscription Center access and support. The Subscription Center is accessible

via the "key" icon near the right end of the program title bar and also via the "Help: Web

Links" menu.

Through the Subscription Center, you can download software updates, service packs, and add-

on applications. You can access training media, such as topical webcasts. Finally, you can also

submit technical support requests via the Subscription Center.

Web Links

Within the Getting Started tab of the ribbon, in the HELP panel, there is a "Web Links" pull-

out menu. The following content can be accessed via the web links within this menu:

Autodesk Simulation - product range

Subscription Center

Services and Support - information

Discussion Group

Training - course information

Autodesk Labs – where you may obtain free tools and explore developing technologies

Manufacturing Community

Figure I.2: Autodesk Simulation "Web Links" pull-out menu

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Introduction


Tutorials

Tutorials are available that demonstrate many of the capabilities of the Autodesk Simulation

software. Each analysis is presented through step-by-step instructions with illustrations to

assist the user. The tutorials are accessed from the "Getting Started: Help: Tutorials"

command. You can download the tutorial models from our “online Data & Downloads

site,” linkable from the top page of the tutorials. Install the models to a local folder of your

choice, such as My Documents\Autodesk Simulation Tutorial Models. We recommend that

you store your tutorial models in a location outside of the Program Files branch. The tutorials

will appear in your default web browser.

Webcasts and Web Courses

Webcasts focus on the capabilities and features of the software, on new functionality, on

accuracy verification examples, and on interoperability with various CAD solid modeling

packages. These streaming media presentations are available for on-demand viewing from

the Subscription Center via your web browser. Similarly, web courses are also available for

on-demand viewing. Web courses are typically longer in duration than webcasts and focus on

more in-depth training regarding the effective usage of your simulation software. The topics

cover a wide variety of application scenarios.

For a list of available webcasts and web courses, follow the "Training" link from the home

page of the Subscription Center. Choose the "Autodesk Algor Simulation" or “Autodesk

Simulation” product in the "Browse the Catalog" list. This leads to the Autodesk

Simulation e-Learning page, in which the available webcasts and web courses are listed

according to topic.

How to Receive Technical Support

Technical support is reachable through three different contact methods. The means you can use

may depend upon the level of support that was purchased. For example, customers with

"Silver" support must obtain their technical support from the reseller that sold them the software.

"Gold" subscription customers may obtain support directly from Autodesk.

Three ways to contact Technical Support:

Reseller: Obtain phone, fax, and/or e-mail information from your reseller.

Subscription Center: Access the Subscription Center from the link provided in the program

interface. Click the Tech Support link on the left side of the page

and then click on the "Request Support" link.

You can also access the Subscription Center directly, using your web browser, at

http://subscription.autodesk.com/. If you do not have Subscription Center access, submit a

request at http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=12338355, or dial

the business center directly at (800) 538-6401. Choose the option for subscription services.

Autodesk Product Support Phone: (866) 487-8680

When contacting Technical Support:

Have your account CSN number ready before contacting Technical Support.

Know the current version number of your software.

Have specific questions ready.

Remember, Technical Support personnel cannot perform, comment on, or make

judgments regarding the validity of engineering work.

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http://subscription.autodesk.com/

http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=12338355

Introduction


Updates

The software is updated with new functionality on a continual basis. The following three

types of releases are provided:

1. A major version: Indicated by the four-digit year of the software release (based upon

the Autodesk fiscal year, not the calendar year)

2. A "subscription" version: Customers with a current maintenance subscription are

eligible for additional releases that may be made available between major product version

releases. These are designated by the addition of the word "Subscription" after the major

version number.

3. A service pack: Incorporates minor improvements to a major or subscription release and

is indicated by the letters "SP" and a service pack number after the major or subscription

version number.

How to Determine the Software Version

Click on the "About" command in the" Help" panel. This dialog box will display the

version that you are using. In addition, the program title bar and the splash screen that

appears at each program launch will indicate the major version number of the software.

However, as with the start menu group name and program shortcut, it will not indicate the

subscription and service pack variants.

How to Obtain an Update

Update notifications are provided via the "Communication Center" within the user interface.

The Communication Center icon is located at the right side of the program window title bar.

The state of the Communication Center icon changes when new information is available. The

Communication Center provides up-to-date product support information, software patches,

subscription announcements, articles, and other product information through a connection to

the Internet. Users may specify how frequently the Live Update information will be polled—

hourly, every four hours, daily, weekly, monthly, or never. When a program update

notification is received, the user will be given the option of downloading and installing it.

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Introduction


Background of FEA

What is Finite Element Analysis?

Finite element analysis (FEA) is a computerized method for predicting how a real-world

object will react to forces, heat, vibration, etc. in terms of whether it will break, wear out or

function according to design. It is called "analysis", but in the product design cycle it is used

to predict what will happen when the product is used.

The finite element method works by breaking a real object down into a large number (1,000s

or 100,000s) of elements (imagine little cubes). The behavior of each element, which is

regular in shape, is readily predicted by a set of mathematical equations. The computer then

adds up all the individual behaviors to predict the behavior of the actual object.

The "finite" in finite element analysis comes from the idea that there are a finite number of

elements in the model. The structure is discretized and is not based on a continuous solution.

In any discrete method, the finer the increments, or elements, the more precise is the solution.

Previously, engineers employed integral and differential calculus, which broke objects down

into an infinite number of elements.

The finite element method is employed to predict the behavior of objects with respect to

virtually all physical phenomena:

Mechanical stress (stress analysis)

Mechanical vibration (dynamics)

Heat transfer - conduction, convection, radiation

Fluid flow - both liquid and gaseous fluids

Electrostatic or MEMS (Micro Electro Mechanical Systems)

Basic FEA Concepts

Nodes and Elements

A node is a coordinate location in space where the degrees of freedom (DOFs) are defined.

The DOFs of a node represent the possible movements of this point due to the loading of the

structure. The DOFs also represent which forces and moments are transferred from one

element to the next. Also, deflection and stress results are usually given at the nodes.

An element is a mathematical relation that defines how the DOFs of one node relate to the next.

Elements can be lines (beams or trusses), 2-D areas, 3-D areas (plates) or solids (bricks and

tetrahedra). The mathematical relation also defines how the deflections create strains and stresses.

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Introduction


Degrees of Freedom

The degrees of freedom at a node characterize the response and represent the relative

possible motion of a node.

The type of element being used will characterize which DOFs a node will require.

Some analysis types have only one DOF at a node. An example of this is temperature in

a thermal analysis.

A structural beam element, on the other hand, would have all of the DOFs shown in

Figure I.3. "T" represents translational movement and "R" represents rotational movement

about the X, Y and Z axis directions, resulting in a maximum of six degrees of freedom.

Figure I.3: Degrees of Freedom of a Node

Element Connectivity – Conventional Bonding

Elements can only communicate to one another via common nodes. In the left half of

Figure I.3, forces will not be transferred between the elements. Elements must have common

nodes to transfer loads from one to the next, such as in the right half of Figure I.4.

Figure I.4: Communication through Common Nodes

Element Connectivity – "Smart Bonding"

With the introduction of "Smart Bonding" it is now possible to connect adjacent parts to each

other without having to match the meshes (i.e., common nodes at part boundaries are no

longer mandatory). This feature is available for both CAD and hand-built models and is

applicable to the following analysis types:

Static Stress with Linear Material Models

Natural Frequency (Modal)

Transient Stress (Direct Integration)

Figure I.5, is a pictorial example of two adjacent parts that may be connected via smart

bonding. Smart bonding is disabled by default for both new and legacy models (that is, those

No Communication Communication

Between the Elements Between the Elements

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Introduction


created prior to implementation of the smart bonding feature). The option may be changed

within the "Contact" tab of the Analysis Parameters dialog box. Note that where nodal

coordinates fall within the default or user-specified tolerance of each other, they will be

matched in the conventional manner. Other nodes along the bonded surfaces or edges – those

at a relative distance greater than the tolerance – will be connected by means of multipoint

constraint equations (MPCs). Also note that the "Use virtual imprinting" option within the

"Model" dialog box of the mesh settings options will minimize the likelihood that smart

bonding will be needed or will occur for CAD-based assemblies. This option attempts to

imprint smaller parts on larger parts where they meet, forcing them to have identical meshes.

Figure I.5: Connection via "Smart Bonding"

Types of Elements

The actual supported and calculated DOFs are dependent upon the type of element being

used. A node with translational DOFs can move in the corresponding directions and can

transmit/resist the corresponding forces. A node with rotational DOFs can rotate about the

corresponding axes and can transmit/resist the corresponding moments.

Briefly, the general element types are as follows (more details will be given in later chapters):

Line elements: A line connecting 2 nodes (such as beams, trusses, springs, thermal rods,

and others).

2-D elements: YZ-planar elements that are triangular or quadrilateral (3 or 4 lines

enclosing an area).

3-D plates or shells: Planar or nearly planar elements in 3-D space. Each must be

triangular or quadrilateral and they represent a thin part with a specified thickness.

Brick (solid) elements: Must be enclosed volumes with 4, 5, or 6 faces (triangular

and/or quadrilateral) and with 4, 5, 6 or 8 corner nodes.

DOFs for element types:

Truss: Translation in X, Y and Z.

Beam: Both translation and rotation in X, Y and Z.

2-D: Translation in Y and Z.

Plate: Five degrees of freedom – out-of-plane rotation is not considered.

Brick: Translation in X, Y and Z.

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Introduction


How Does Autodesk Simulation Mechanical Work?

The software transforms an engineering model with an infinite number of unknowns into

a finite model.

This is an idealized mathematical model.

The model is defined by nodes, elements, loads and constraints. The user interface can be effectively used for the design, analysis and evaluation phases of a

typical design process.

The simulation software can be extremely useful during the initial concept and design phase to

identify areas that can be improved.

The simulation software can also be used to quickly evaluate a concept, saving time and

engineering resources.

This does not necessarily replace the testing needed to evaluate a final design; however

the goal is to minimize the prototype and testing stages of design.

The General Flow of an Analysis in Autodesk Simulation Mechanical

Create a Mesh

Start the simulation program

Open your model in the FEA Editor environment

Select the analysis type

Create your mesh

Define the FEA Data

Assign the loads and constraints

Define the material

Define the analysis parameters

Run the Analysis

Review and Present Results

Review the desired result types

Save images and animations

Create presentations and HTML reports

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Introduction


Stress and Strain Review

Equations Used in the Solution

A complex system can be broken into a finite number of regions (elements), each of which

follows the equations below:

L

AEF

dx

E

A

F

L

0

Where, σ = stress, F = force, A = area

ε = strain, E = modulus of elasticity

δ = displacement, L = length

When the interaction of each region with its neighbor (through the nodes) is considered, a

system of equations is developed:

{f} = [K] {x}

Known Unknown

where, {f} is the vector that represents all of the applied loads. [K] is the assemblage

of all of the individual element stiffnesses (AE/L) and {x} is the vector that

represents the displacements.

Since the applied load vector and element stiffnesses are known from the user input, the

equation can be solved using matrix algebra by rearranging the equation as follows for the

displacement vector:

fKx 1

Strains are computed based on the classical differential equations previously discussed. Stress can

then be obtained from the strains using Hooke’s Law. These basic equations do not require the use

of a computer to solve. However, a computer is needed when complexity is added, such as:

1. Geometric complexity (makes the elasticity equation impossible to solve).

2. Variation in material properties throughout the body.

3. Multiple load cases and complex or combined loading.

4. Dynamics.

5. Large systems (require many equations to solve).

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Introduction


In practice, the direct inversion is extremely difficult and sometimes unstable. In FEA,

matrices can be 50,000 x 50,000 or larger. As a result, other solution methods for this linear

equation have been developed. All of these methods use the basic principles of a

mathematical method called Gaussian Elimination. The details of this method will not be

discussed here, but may be obtained from any numerical programming text.

Since differentiation cannot be performed directly on the computer, approximation techniques

are used to determine the strain in the model. Since an approximation technique is used for

the strains, the finer the mesh, the better the approximation of the strain. For a linear static

analysis, stress has a linear relation to strain. Therefore, the stresses will have the same

accuracy as the strains.

For more complex analyses, more terms are needed. The equation below is needed to

represent a true dynamic analysis:

xKxcxmf

where the additional matrices and vectors are,

m = mass, x = acceleration (second derivative of displacement versus time)

c = damping, x = velocity (first derivative of displacement versus time)

Limits of Static Stress with Linear Material Models

Deformations are small

Strains and rotations are small

Changes in stiffness through the model are small

Changes in boundary conditions are small

Changes in loading direction with deformations are small

Material remains in the linear elastic range

Mechanical Event Simulation (MES) Overcomes Limitations

MES supports:

Large deformations

Changing boundary conditions

Loads moving as the model moves or deforms

Nonlinear material behavior

Time-dependent loading

Large-scale motion

Event visualization capabilities:

Viewing results with respect to time using the Results environment

Animation tools

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Introduction


MES simulates:

Motion

Impact

Real-time observation of deformations, stresses and strains

Failure due to the following: material yielding, local and structural buckling, permanent

deformations - residual stress

MES capabilities are included within the Autodesk Simulation Mechanical product. It is also

included within the higher-level Autodesk Simulation Multiphysics product.

For information and training regarding MES, refer to the Autodesk Simulation Mechanical –

Part 2 training course.

Hand-Calculated Example

Refer to Appendix A for an example of displacement and stress results for a simple truss

structure. A theoretical solution using fundamental equations is presented. In addition, a

hand-calculated solution based on the finite element method is presented and its results

compared with those obtained by the FEA software.

Heat Transfer Review

Equations Used in the Solution

Heat transfer, as applied to FEA, is actually a conduction problem. The heat loads are

boundary conditions. The primary results are a temperature profile and the heat flux through

the body of the structure.

Conduction is the flow of heat in the body of the structure. This is what is being solved in an

FEA problem. The properties of conduction are controlled by the part definition. Only the

thermal conductivity (k) is needed for a steady-state analysis. For a transient analysis, the

mass density and specific heat will also be required. The governing equation is:

L

TkAq

where: k = Thermal conductivity

A = Area

T = Change in temperature

L = Length

The two most common loads for a thermal analysis are convection and radiation loads. These

loads are applied to a surface. The equation for the heat flow due to convection is:

TThAq s

where: h = Convection coefficient

A = Area

Ts = Temperature of the surface

T = Ambient temperature

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Introduction


The equation for the heat flow due to radiation is:

44.. bTTFVAq

where: = Emissivity which describes the surface finish for gray bodies. (If = 1.0, it

is a true blackbody.)

= Stefan-Boltzmann constant for radiation

A = Area

V.F. = View factor from the surface to the infinite source

T = Ambient temperature (in units of absolute temperature)

Tb = Temperature of the node (in units of absolute temperature)

Linear Dynamics Review

Equation for Dynamic Analyses

The basic equation of dynamics is:

[m]{a}+[c]{v}+[k]{x}=0

where:

[m] = the mass matrix

{a} = the acceleration vector

[c] = the damping constant matrix

{v} = the velocity vector

[k] = the stiffness matrix

{x} = the displacement vector

A natural frequency analysis provides the natural vibration frequencies of a part or assembly

based on a linear eigenvalue solution. Because the above equation is solved in this linear

solution, only mass and stiffness are taken into account. No damping is used. In addition,

loads are ignored. As a result, actual displacement output is meaningless except to define the

shape of the natural frequency mode. Note that loads are taken into account for a natural

frequency with load stiffening analysis, assuming the loads produce membrane stresses that

affect the stiffness of the structure.

Constraints have a very significant effect on the solution. When no boundary conditions or

insufficient boundary conditions are used, rigid-body movement or modes will be found.

Unlike a static solution, this is acceptable in a modal analysis.

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Using Autodesk®

Simulation Mechanical or

Multiphysics

Chapter Objectives

Introduction to the user interface

o Commands - Ribbon

o Keyboard

o Mouse

o View Cube and other view controls

Complete an example of using Autodesk Simulation

o Overview of opening an Autodesk Inventor CAD model and creating a mesh

o Overview of adding loads and constraints to a model

o Overview of defining material properties

o Overview of performing an analysis

o Overview of reviewing results

o Overview of generating a report

Navigating the User Interface

In this section, we will introduce you to the Autodesk Simulation user interface. This

interface is the same for each of the available packages, including the Simulation Mechanical

and Simulation Multiphysics products. The only difference will be with regard to which

advanced features or capabilities are enabled.

We will begin with an overview of the major components of the graphical user interface.

Then we will discuss the Ribbon, keyboard, mouse, View Cube, and additional view controls.

Please note that the behavior of the keyboard, mouse and View Cube – as discussed within

this manual – are based on the default program settings for a clean installation of the product.

Many of the features to be discussed are customizable via tabs and settings within the

"Application Options" dialog box, reachable via the "Tools: Application Options"

command.

Figure 1.1 on the next page, along with the legend that follows it introduces the major

components of the user interface. This manual is based on Autodesk Simulation Multiphysics

2013. Users of other versions may encounter differences between their version and the

interface described herein.

Chapter

1

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Chapter 1: Using Autodesk®

Simulation Mechanical or Multiphysics


Figure 1.1: Autodesk Simulation Mechanical or Multiphysics User Interface

Interface Legend:

A. Application Menu: Files can be opened and accessed from the Application Menu. Other commands that are

available here include Merge, Export and Archive.

B. Quick Access Toolbar (QAT): Provides quick access to commonly used commands and is fully customizable.

The QAT image shown here includes a number of commands in addition to the default set.

C. Ribbon Tabs: The Ribbon tabs are located just below the title bar and are used to select different sets of

logically grouped commands.

D. Ribbon Commands: The Ribbon provides access to many commands for drawing, meshing, setting up,

analyzing, manipulating, and reviewing the model. Different command sets are displayed for each of the

three environments of the user interface (FEA Editor, Results, or Report).

E. Title Bar: Displays the program name and version.

F. Product Center: Provides links to the Autodesk Subscription Center, Autodesk Exchange Apps, and

Communication Center. Type a keyword or phrase into the field on the left to search the Wiki help.

G. Browser: The browser (tree view) has unique contents for each environment. For the FEA Editor, it shows the

parts list and the units, various properties, and loads that will be used for the analysis. In the Results

environment, you see a list of results presentations and other post-processing-specific content. The components

of the analysis report will be listed in the browser within the Report environment. You can also close or

pin/unpin the browser.

H. Display Area: The display area is where the modeling activity takes place. The title bar of the window displays

the current environment and the model name. The FEA Editor environment is used to create the model, add the

loads and constraints, and perform the analysis. The Results environment is used to view results and to create

images, graphs, and animations. The Report environment will be used to produce a formal report of the analysis,

including desired results presentations. The ViewCube and Navigation Bar are also in the Display area by default.

I. Miniaxis and Scale Ruler: The miniaxis shows your viewpoint with respect to the three-dimensional

working area. The scale ruler gives you a sense of the model size.

J. Status Bar: The status bar displays important messages and command prompts.

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Commands

Autodesk Simulation Mechanical and Multiphysics access program functions through the

ribbon, context menus, quick access toolbar (QAT), and Application Menu. The available

commands and menus vary for each program environment (FEA Editor, Results, and Report).

The Ribbon is positioned at the top and is customizable. You can move the panel positions

within the same Ribbon tab.

The commands are logically grouped into panels and tabs. For example, the Mesh tab

includes Mesh, CAD Additions, Structured Mesh, and Refinement panels. Each panel will

have a specific set of commands. You can add these commands to the quick access toolbar so

that they can be easily accessed while any ribbon tab is displayed. To do this, right-click the

command in the panel and select "Add to Quick Access Toolbar," as shown in Figure 1.2.

Figure 1.2: Adding a Ribbon Command to the QAT

Most of the tabs, panels, and commands will not appear until an existing model is opened or a

new model is created. Figure 1.3 shows a typical context menu accessed by right-clicking in

the display area after selecting a surface on the model. Context menus can be used to add

loads and constraints, among other tasks.

Figure 1.3: Context Menu

In some cases there where will be too many commands to be all displayed on the panel. In

these situations you can click on the panel options button to gain access to further commands

as shown in Figure 1.4.

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Figure 1.4: Additional Panel Commands

Using the Keyboard and Mouse

The keyboard and mouse will both be used to operate within the user interface. The keyboard

will be used to enter the required data for loads, constraints, material properties, and so on. It

will also be used to modify the behavior of particular mouse operations. That is, certain

keyboard keys, when held down, will change the behavior of the mouse.

The software supports a number of different mouse configurations. This document assumes that

the default template for a new installation is in effect. However, user settings, or those retained

from a prior Autodesk Simulation installation, may cause the behavior to differ from that

described herein. To ensure that your mouse actions follow the descriptions in this book, access

the "Tools: Application Options: Mouse Options" dialog box and choose the "Autodesk

Simulation" template.

The left mouse button will be used to select items. How items are selected will depend upon

the selection mode chosen in the "Selection: Shape" pull-out menu or Ribbon. The type of

objects that are selected (such as lines, vertices, surfaces, parts, edges, or elements) will

depend upon the selection mode chosen in the "Selection: Select" pull-out menu or Ribbon.

Holding down the <Ctrl> key, while left-clicking on the object, will toggle the selection state

of the clicked object. That is, unselected objects will be added to the selection set and

previously selected items will be removed from the selection set. Holding down the <Shift>

key while left-clicking will only add clicked objects to the selection set (this will have no

effect on already selected items). Finally, holding both <Ctrl> and <Shift> while left-

clicking will only remove clicked objects from the selection set (this will have no effect on

items that are not already part of the current selection set).

Pressing the right mouse button with the cursor hovering over items in the browser will access

a context menu with commands relevant to the item under the cursor. When items are

currently selected, either within the browser or display area, the right-click context menu will

display commands and options that are specifically relevant to the selected items. For

example, if a surface is selected, only surface-based commands will appear in the context

menu. You may right-click anywhere in the display area when items are selected to access

the context menu. However, to access the context menu within the browser area, you must

right-click with the cursor positioned on one of the selected headings.

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If a mouse has a wheel, rolling the wheel will zoom in or out on the model. Holding down the

middle mouse button or wheel and dragging the mouse will rotate the model. Pressing the

<Ctrl> key, while holding the middle button and dragging the mouse, will pan the model,

moving it within the display area. Pressing the <Shift> key while dragging the mouse with

the middle button down will zoom in and out, making the model larger as the mouse is moved

upward and smaller as it is moved downward. You will likely find the use of the middle

mouse button and wheel to be more convenient than choosing a command like "Rotate" or

"Pan," clicking and dragging the mouse, and then pressing <Esc> to exit the command.

Finally, the X, Y, or Z key on the keyboard may be held down while dragging the mouse with

the middle button held down. Doing so will rotate the model, as before, but constraining the

rotation to be only about the corresponding X, Y, or Z global axis direction. You may also

use the left and right cursor keys on the keyboard while holding down X, Y, or Z to rotate

about these axes in fixed increments (15 degrees by default). The rotation increment is

customizable via the "Tools: Application Options: Graphics: Miscellaneous" dialog box.

Introduction to the View Cube

As is true for the mouse, the software also supports a number of different view configurations.

This document assumes that the default view options template and view navigation settings for a

new installation are in effect. However, user settings, or settings retained from a prior Autodesk

Algor Simulation or Autodesk Simulation installation, may cause the view orientations and

behavior to differ from those described throughout this document. To ensure that your view

commands follow the descriptions in this book, access the "Tools: Application Options:

Views Options" dialog box and choose the "Autodesk Simulation" template.

Next, access the "Graphics" tab of the same "Options" dialog box, select "Navigation Tools"

from the items listed on the left side of the dialog box, and click on the "View Cube" button.

Click the "Restore Defaults" button followed by "OK" to exit the View Cube Properties dialog.

Finally, click the "Steering Wheel" button. Click the "Restore Defaults" button followed by

"OK" to exit the "Steering Wheels Properties" dialog box. Click "OK" to exit the "Options"

dialog box.

Users of other Autodesk® products, such as AutoCAD® or Autodesk® Inventor® will likely

already be familiar with the View Cube and associated additional view controls.

The View Cube will be located in the upper right corner of the display by default but may be

relocated. The appearance will change depending upon whether the view is aligned with a

global plane and whether the cursor is near the cube or not. The View Cube, in its various

appearances, is shown in Figure 1.5.

Figure 1.5: View Cube Appearance

(a) Cursor not near the

View Cube

(b) Cursor on View Cube

(view not aligned to a

standard face)

(c) Cursor on View Cube

(standard face view)

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The six standard view names, as labeled on the cube faces, are the Top, Bottom, Front, Back,

Left, and Right. These may be selected by clicking near visible face names on the cube, as

shown in Figure 1.5 (b) or by clicking the triangular arrows pointing towards the adjacent faces,

as shown in Figure 1.5 (c), which shows the cursor pointing to the arrow for the Bottom view.

In addition, there are clickable zones at each corner and along each edge of the View Cube.

Clicking on a corner will produce an isometric view in which that particular corner is

positioned near the center and towards you. Clicking an edge will produce an oblique view,

rotated 45 degrees, Half-way between the views represented by the two adjacent faces.

When the cursor is near the View Cube, a "Home" icon will appear above it and to the left,

providing easy access to the home view. This is an isometric view having the corner between

the Front, Right, and Top Faces centrally positioned and towards you by default. The home

view may be redefined by right-clicking the Home icon and choosing the "Set Current View

as Home" command while viewing the model positioned as desired.

When one of the six standard views is active and the cursor is near the View Cube, two

curved arrows will appear above and to the right of the cube, as seen in Figure 1.5 (c). These

are used to rotate the model to one of the four possible variants of the particular standard

view. Each click of an arrow will rotate the model 90 degrees in the selected direction.

When the face being viewed is changed via the View Cube, the model may move to the

selected view in the manner that requires the least amount of motion. For example, say we

are first looking at the Right view, with the word "Right" positioned upright (that is in the

normal reading position). Now, if we click the downward arrow above the cube, the model

will rotate 90 degrees to reveal the top face. The Top view will be rotated 90 degrees

clockwise from the upright orientation (that is, the word "Top" will read in the vertically

downward direction). Activating the "Keep scene upright" option will cause the Front,

Back, Left, and Right views to automatically be oriented in the upright position (Top above,

Bottom below) when changing to any of these views. You may, however, rotate the view

after initial selection, if desired. Go to "Tools: Application Options: Graphics: Navigation

Tools: View Cube" to locate the "Keep scene upright" setting. It is activated by default.

The point of this discussion is that whenever a new face is selected using the View Cube, the

resultant view rotation may differ, depending upon the prior position of the model. If the resultant

orientation is not what is desired, simply click one of the curved arrows to rotate the view.

Additional View Controls

Immediately below the View Cube is a pallet of additional view controls.

This consists of seven tools, each of which may be individually enabled or

disabled. All are on by default. Figure 1.6 shows the view control pallet.

From top to bottom, the seven tools are as follows:

Steering Wheels

Pan

Zoom

Orbit

Center

Previous View

Next View

Look At

Each of these icons, except for the Previous and Next commands, function as

a toggle—clicking it once to activate a command and again to deactivate it.

Fig

ure 1

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all

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Several of the tools, such as Pan, Previous, and Next are self-explanatory

The "Zoom" tool includes a fly-out menu allowing the choice of one of four different

zooming modes—Zoom, Zoom (Fit All), Zoom (Selected), and Zoom (Window). The first of

these causes the model to become larger as the cursor is moved upward in the display area and

smaller when it is moved downward. The Fit (All) mode encloses the extents of the whole

model. After selecting objects in the display area, the Zoom (Selected) tool fits the selected

items into the display area. Finally, after selecting the Zoom (Window) tool, you click and

drag the mouse to draw a window defines the area you wish to expand to fill the display area.

The “Look At” tool includes a fly-out menu allowing the choice of one of three different

Look At modes—Look At, Look At Surface, and Look At Point.

Look At Surface positions the view with the clicked surface parallel to, or tangent to,

the screen and zooms in or out to enclose the whole surface within the display area.

Look At Point places the surface to which the clicked point belongs parallel to, or

tangent to, the screen but encloses the view more tightly, with the clicked point

centered in the display area.

Look At places the surface to which the clicked point belongs parallel or tangent to

the screen but does not modify the current amount of zoom. The viewpoint rotates

and/or pans to center the clicked point, but the view is not zoomed in or out.

The "Orbit" tool has two variants, selectable via a fly-out menu—Orbit, and Orbit

(Constrained). The former allows the model to be rotated freely in any direction. The

Constrained option causes the model to rotate only about the global Z-axis, similar to pressing

the Z key while dragging the mouse with the middle button depressed.

The "Center" tool is used to center a point on the model within the display area. Click with

the mouse to specify the desired center point after selecting the Center command. This point

also becomes the display pivot point, about which the model pivots when being rotated.

The "Steering Wheel" tool is customizable and, in its default setting, produces the Full

Navigation Wheel shown in Figure 1.7. The full navigation wheel floats above the model

view, following the cursor position. It provides an additional access method for several

functions found elsewhere on the view tools pallet as well as a few additional functions.

Figure 1.7: Full Navigation Wheel

The "Rewind" button on the navigation wheel presents a timeline of thumbnails representing

various views that have been used during the modeling session. Simply release the mouse

button with the cursor positioned at the thumbnail representing the view to which you wish to

jump. This is more convenient than pressing the previous or next view buttons multiple times.

For additional information concerning these view controls, consult the Wiki Help.

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Legacy View Controls in Autodesk Simulation Mechanical and Multiphysics

Traditional view controls and options are also provided via the View tab of the command

ribbon at the top of the screen. Options for displaying or hiding the mesh or model shading

may be found here as well as eight pre-defined, standard view orientations. The orientations

will depend upon the currently active Views Options template (previously discussed in the

"Introduction to the View Cube" section of this chapter).

There is also a "User-defined Views" dialog box that may be used to save, modify, or restore

custom views. Additional capabilities include a local zoom feature and display toggles for the

scale ruler, mini axis, and perspective mode.

The "Local Zoom" feature displays a small rectangle that represents the area to be

magnified. A larger rectangle shows an overlay of the magnified region. You may click on

and drag the local zoom window to position it anywhere on the model within the display area.

The size of the local zoom area and magnified overlay and also the zoom level can be

customized via the "Application Menu: Options: Graphics: Local Zoom" dialog box.

For additional information concerning the legacy view controls, consult the Wiki Help.

Steel Yoke Example

This example is an introduction to static stress analysis with linear material models. The

example will give step-by-step instructions to create a mesh and analyze a three-dimensional

(3-D) model of a steel yoke under an applied force. There are three sections:

Setting up the model – Open the model in the FEA Editor environment and create the mesh

on the model. Add the necessary forces and boundary conditions and define the model

parameters. Visually check the model for errors with the Results environment.

Analyzing the model – Analyze the model using the static stress with linear material models

processor.

Reviewing the results – View the displacements and stresses graphically using the Results

environment.

Use the Inventor solid model, yoke.ipt, located in the "Chapter 1 Example Model\Input File"

folder in the class directory (or extracted to your computer from the solutions archive) to

create a simple model of the steel yoke shown in Figure 1.8. The right half of the small hole

will be fixed. A force of 800 pounds will be applied to the left half of the large hole and

acting towards the left, as shown in the figure. The yoke is made of Steel (ASTM-A36).

Analyze the model to determine the displacements and stresses.

Figure 1.8: Steel Yoke Model

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Opening and Meshing the Model

The FEA Editor environment is used to create a mesh for all solid models. You can open

CAD solid models from any of the CAD solid modelers that Autodesk® Simulation

Mechanical supports. You can also open models of any of the universal CAD formats that are

supported. Here we are going to open an Autodesk® Inventor® CAD model. You do not

have to have Inventor installed on the simulation computer.

"Start: All Programs:

Autodesk: Autodesk

Simulation 2013: Autodesk

Simulation Mechanical 2013"

If not already started, press the Windows "Start" button

and access the "All Programs" pull-out menu. Select the

"Autodesk" folder and then the "Autodesk Simulation

2013" pull-out menu. Choose the "Autodesk Simulation

Mechanical 2013” (or “…Multiphysics 2013”) command.

"Getting Started: Launch:

Open"

If the Open dialog box is not already displayed, click the

"Open" command in the “Launch” panel. Alternatively

you can select “Open” from the quick access toolbar or

Application Menu.

"Autodesk Inventor Files

(*.ipt, *.iam)"

Select the "Autodesk Inventor Parts (*.ipt, *.iam) option

in the "Files of type:" drop-down box.

"Yoke.ipt" Select the file "Yoke.ipt” in the “Chapter 1 Example

Model\Input File” directory.

“Open” Press the “Open” button.

"Linear: Static Stress with

Linear Material Models"

"OK"

A dialog box will appear asking you to choose the analysis

type for the model. From the pull-out menu, choose

"Linear: Static Stress with Linear Material Models" and

press the "OK" button.

The model will appear in the FEA Editor environment.

"Mesh: Mesh: Generate 3D

Mesh"

Select the "Mesh” tab. Click the “Generate 3D Mesh"

command in the "Mesh" panel to create a mesh with the

default options.

"View: Navigate: Orbit"

Select the "View" tab. Click on the "Orbit" button in the

"Navigate" panel. You can also access Orbit from the

Navigation bar.

Mouse

Click the left mouse button and drag the mouse to rotate the

model and inspect the mesh all around it. This mesh appears

to be acceptable. When done inspecting the mesh, position

the model so that you can see the inside of the small hole as

shown in Figure 1.9. These surfaces will be constrained.

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Figure 1.9: Yoke Rotated to Select Constrained Surfaces

Setting up the Model

The FEA Editor environment is also used to specify all of the element and analysis parameters

for your model and to apply the loads and constraints. When you initially come into the FEA

Editor environment with the yoke model, you will notice a red X on certain headings in the

browser. This signifies that this data has not yet been specified. You will need to eliminate

all of the red Xs before analyzing the model. After creating the mesh, the "Element Type"

heading in the browser is already set to "Brick" and the default "Element Definition"

parameters have been accepted. The material information is also imported from Inventor.

Adding Constraints

Constraints describe how a finite element model is tied down in space. If an object is welded

down so that it can neither translate nor rotate, the object is fully constrained.

"Setup: Constraints: General

Constraint"

Select the "Setup" tab. Click on the "General

Constraint" command in the "Constraints" panel. The

dialog box shown in Figure 1.10 will appear. Also an

additional mini-toolbar will show up allowing the user to

change the selection shape and selection object on the fly.

Mouse Click on the surface on the right side of the small hole as

oriented in Figure 1.9.

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Figure 1.10: Surface Boundary Condition Dialog Box

"Fixed"

Press the "Fixed" button. Note that all 6 of the checkboxes

in the "Constrained DOFs" section to the left are

activated. This means that the nodes on this surface will be

totally constrained.

"OK"

Press the "OK" button to apply these boundary conditions.

Now there will be green triangles on the nodes of the

surface that was selected. This signifies a fully constrained

boundary condition.

Adding Forces to the Model

In this section, you will add the 800 lb force in the –X direction to the large hole.

Mouse

Click and drag using the middle mouse button to rotate the

model. Position it so that you can see the surfaces of the

large hole where the load is to be applied (that is, the single

half surface at the left side of the hole).

"Loads: Forces…"

Click on the "Force" command in the "Loads" panel. The

dialog box shown in Figure 1.11 and the mini-toolbar will

appear.

Mouse Click on the surface on the left side of the large hole.

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Figure 1.11: Surface Forces Dialog Box

-800 Type "-800" in the "Magnitude" field to add a force of

800 pounds each in the negative X direction to the surface.

"X" Select the "X" radio button in the "Direction" section to

add surface forces in the X direction.

"OK"

Press the "OK" button to apply the surface force. Now

there will be green arrows on the surface that was selected.

They are pointed in the negative X direction.

"View: Navigate: Orientation:

Top View"

Select the "View" tab. Click on the options button at the

bottom of "Orientation" command in the "Navigate"

panel. Select "Top View" from the pull-out menu. The

model should now look like Figure 1.12. The View Cube

can also be used to access the views.

Figure 1.12: Yoke after Boundary Conditions and Loads are applied

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Assigning the Parameters

Once the model has been constructed and the loads and constraints have been applied, use the

FEA Editor environment to specify material properties.

Mouse Right-click on the "Material" heading for Part 1.

"Edit Material…" Select the "Edit Material…" command. The "Element

Material Selection" dialog box will appear.

"Steel (ASTM-A36)" Highlight the "Steel (ASTM-A36)" item from the list of

available materials as shown in Figure 1.13.

Figure 1.13: Element Material Selection Dialog Box

"Edit Properties" Press the "Edit Properties" button to view the material

properties associated with this steel.

"OK" Press the "OK" button to exit the "Element Material

Specification" dialog box.

"OK" Press the "OK" button to accept the information entered in

the "Element Material Selection" dialog box for Part 1.

"Yes" Accept the warning to override default material defined

within Inventor.

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"Analysis: Analysis: Check

Model"

Select the "Analysis" tab. Click on the "Check Model"

command in the "Analysis" panel.

"Tools: Environments: FEA

Editor"

Select the "Tools" tab. Press the "FEA Editor" command

in the "Environments" panel.

"View: Orientation: Isometric

View"

Select the "View" tab. Click on the options button at the

bottom of the "Orientation" command in the "Navigate"

panel. Select "Isometric View" from the pull-out menu.

Analyzing the Model

"Analysis: Analysis: Run

Simulation"

Select the "Analysis" tab. Click on the "Run Simulation"

command in the "Analysis" panel. When completed, the

model will be displayed in the Results environment and the

Displacement Magnitude will be displayed, as shown in Figure

1.14 below. Note the maximum displacement value.

Figure 1.14: Yoke Model as Displayed in the Results Environment

Reviewing the Results

"Results Contours: Stress: von

Mises" Note the maximum von Mises value.

The maximum von Mises stress and maximum deflection should closely match the values in

the table below.

Maximum von Mises Stress

(psi)

Maximum Displacement

(in)

~1,900 ~0.0004

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Viewing the Displaced Shape

Viewing the displaced shape is always the best way to get an overall understanding of how the

model reacted to the applied load. A displaced model alone or a displaced model overlaid with

an undisplaced model can be displayed.

"Results Contours: Displaced

Options"

Click on the options button next to the "Show Displaced"

command in the "Displacement" panel. Then select

"Displaced Options" command.

"Transparent" Select the "Transparent" radio button in the "Show

Undisplaced Model As" section.

Mouse

Press the "X" button in the upper right corner of the

"Displaced Model Options" dialog box to close it.

Creating an Animation

"Results Contours: Captures:

Start Animation"

Select the "Results Contours" tab. Click on the "Start

Animation" command in the "Captures" panel.

"Captures: Stop Animation"

Click on the "Stop Animation" command in the

"Captures" panel.

The preceding steps animated the results within the display area but did not create an

animation file that we can place in our report. In the following steps, we will export an

animation file that can be included in the report or copied to and played on any computer.

"Animate: Save As AVI"

Click on the "Animate" command in the "Captures"

panel. Then select "Save As AVI" option.

"Displacement

Animation"

Rather than using the default file name, type

"Displacement Animation" into the "File name:" field.

"Save" Press the "Save" button to save the animation to an AVI

file format.

"No" Press the "No" button when asked if you want to view the

animation.

Generating a Report

In this section, you will automatically create an HTML report using the Report Configuration

Utility.

"Tools: Report"

Select the "Tools" tab. Click on the "Report" command

in the "Environments" panel.

"Report: Setup: Configure"

Select the "Configure" command in the "Setup" panel.

This will open the dialog box shown in Figure 1.15.

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Figure 1.15: Report Configuration Utility

NOTE: Clicking on any of the checkboxes will toggle the inclusion state of the item (i.e. whether it is

to be included or excluded from the HTML report). When selecting included portions of the

report, to modify them. Click on the item name and not on the checkbox. This will select the

item without toggling the checkbox state.

Mouse

Activate the checkbox next to the "Logo" heading. This

will include the default Autodesk® logo at the top of the

report.

Note that you may also customize the logo by browsing to and selecting your own image file.

Several different image file formats are supported. The logo size and alignment may also be

adjusted by right-clicking on it and choosing the "Format Image" command. You may also

select the image and then click and drag the handles that appear around the image border

while it is selected to resize it.

Mouse Select the "Project Name" heading.

Mouse: Yoke Design

Click and drag the mouse to select the text, "Design

Analysis" and type "Yoke Design" to replace it.

Mouse: Analysis of Yoke under

800 lbf Loading

Click and drag the mouse to select the text, "Project Title

Here" and replace this text by typing "Analysis of Yoke

under 800 lbf Loading".

Mouse Select the "Title and Author" heading.

Your Name Type your name into the "Author" field.

Your Department Type your department name into the "Department" field.

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Mouse Select the "Reviewer" heading.

Person who checked model Type the name of the person who checked the model into

the "Reviewer" field.

Department of person who

checked the model

Enter the name of the department of the person who

checked the model into the "Department" field.

Passed all FEA tests Type "Passed all FEA tests" into the "Comments" field.

Mouse

Deselect the "Executive Summary" item by clicking on

the associated checkbox. This item will be excluded from

the report.

NOTES: Text can be added as desired within the "Executive Summary" section using the built-in word

processor features. A variety of font and paragraph styles are included, such as bullet or

numbered lists, tables, tabs, and various text justification settings.

The following sections are automatically generated and cannot be modified. The analyst may

only include or exclude these items or alter their order of appearance within the report:

Summary

Analysis Parameters

Parts

Element

Material

Loads

Constraints

Probes

Rotating Frames (applicable to fluid flow analysis)

Results Presentations

Processor Log Files Group

Code Checking – General

Code Checking – Detailed

Mouse

Deselect the "Results Presentations" checkbox. Rather

than including the default image of the results window, we

will include the previously generated animation.

"Tree: Add AVI File(s)..."

Access the TREE pull-down menu and select the "Add

AVI File(s)..." command. This will allow you to include

an animation file within the report. Alternately, you can

right-click in the report tree area and choose the "Add AVI

File" command.

"Displacement Animation.avi" Browse to and select the previously created animation file

"Displacement Animation.avi".

"Open" Press the "Open" button. A "Displacement Animation"

heading will appear in the report tree and it will be selected.

The default text within the "Header Text:" field will match the filename. We will leave it as

is. Optional text may be placed in the report below the animation, if desired, by entering the

desired text into the "Caption" field. We do not need to include a caption for this example.

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Mouse

Click and drag the "von Mises Stress Animation" heading in

the report tree and release it over the "Processor Log Files"

heading. This will reorder the report, placing the animation

immediately before the processor log files.

"Generate Report"

Press the "Generate Report" button. This will automatically

bring up the report, which will appear as shown in Figure 1.16

below. You can scroll through and review the full report.

Figure 1.16: Completed Report

NOTE: The default title image is the model as it currently appears within the FEA Editor environment. A

different image may be substituted for this one and/or the image may be resized using the report

configuration utility. To adjust the image size or alignment right-click on it and choose "Format

Image" command. You may also select the image and then click and drag the handles that appear

around the image border while it is selected to resize it.

A completed archive of this model (yoke.ach), including results, is located in the "Chapter 1 Example

Model\Results Archive" folder in the class directory or in the copy of the solutions folders on your

computer.

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